|
|
In 1867, Theodor Meynert showed that the laminated form of the cortex was due to the distribution in parallel layers of different categories of neurons (Meynert 1867-1868) . |
|
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In 1867, Helmholtz, in Handbuch de Physiologischen Optik, Volume III, said that "disparate images from corresponding retinal points enter the sensorium distinct and intact, and that their union into a single image is an unconscious act of judgement dependent on prior experience" (Turner 1976:248). |
|
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In 1867, Fleeming Jenkin, in a review of Origin of Species, pointed out that variation would be eliminated with an inheritance which was a blend of the parents. Blending inheritance is analogous to mixed paints. This criticism caused Darwin, in subsequent editions, to resurrect Lamarck's theory of acquired characters, which was not finally put aside until the rediscovery of Mendel and unit characters in 1900. |
|
|
In 1867, Darwin, working on his theory of sexual selection and
failing to understand why caterpillars are often brightly adorned, wrote Wallace, who explained his theory of warning coloration, which today is proven. |
|
|
In 1867, Aleksander Onufriyevich Kovalevsky extended the germ layer concept to invertibrates. |
|
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In 1867, Wilhelm Griesinger published the second edition of his psychiatric textbook in which he said that mental diseases are
brain diseases and that the onset of psychosis was experienced as an intrusion of a 'thou' on the 'I,' or ego. |
|
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In 1867, Karl Marx, in Das Kapital, maintained the value, or exchange relation, of commodities is characterized by its alienation
from its use-value, and thus its value as the product of human labor, which the capitalist treats as a variable and against which he accounts his surplus. |
|
In 1868, Josef Breuer and Ewald Hering, by occluding the trachea at the end of inhaling or exhaling, demonstrated that
the lungs 'self-regulate' breathing, i.e., they contaIn receptors that detect the degree to which they are stretched. These
receptors transmit signals to the brain via the vagus nerve which initiates the opposite signal back to the lungs. This was one of the first 'feedback' mechanisms demonstrated in mammals. |
|
In 1868, Ångström, in an atlas of the solar spectrum, measured the wavelengths of over a thousand spectral lines in units which came to be called an 'angstrom' in his honor. |
|
In 1868, Boltzmann, in "Studien über das Gleichgewicht der lebendingen Kraft zwischen bewegten materiellen Punkten"
on thermal equilibrium, extended Maxwell's theory of the distribution of energy among colliding molecules in equilibrium
in a conservative force field. By assuming a fixed amount of energy divided among a finite number of molecules, i.e., all
combinations of energies are equally probable, the problem could treated by combinatorial analysis. "The result was a
new exponential formula, now known as the 'Boltzman factor' and basic to all modern calculations in statistical mechanics" (Brush 1976:261). |
|
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In 1868, Maxwell, in "On Governors," published a mathematical analysis of governors, the first significant paper on feedback mechanisms. |
|
|
In 1869, Dmitri Ivanovich Mendeléev and, independently, Julius Lother Meyer formulated the 'Periodic law.'
Meyer showed that Newlands' 'Law of octaves' only holds for the first two periods. He also evolved the
atomic volume curve which represented graphically the relation between the atomic weights and the volumes of the elements, expressed by
dividing atomic weights by specific gravities. Mendeléev placed the chemical elements in seven rows in an order where those
elements having similar chemical properties were aligned vertically. He also left gaps in his table where he predicted elements would
be found, which, in due course, they were, removing any doubt as to the validity of the periodic table. |
|
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In 1869, Eduard von Hartmann published Philosophie des Unbewussten, in which the 'unbewussten',' or 'unconscious,'
included both Georg Frederick Hegel's 'idée' and the 'will' of Schopenhauer and others. Modern discussions of the unconscious are generally dated from this time. |
|
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In 1869, George M. Beard distinguished 'neurasthenia,' a nervous disease of men, from hysteria, a women's disease, as, in an earlier time, men's 'hypochondriasis' had
been distinguished from women's ' vapeurs.' Subforms of neurasthenia came to be called phobias. |
|
In 1869, Karoly Maria Benkert invented 'homosexuality' as a behavioral category. |
|
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In 1869, Francis Galton, in Hereditary Genius, suggested a genetic basis for intelligence. He established that the
science of heredity could be concerned with deviations measured in statistical units. His discovery of the standard deviation
gave him the mathematical machinery to handle variability and to treat population as a unit of explanation. |
|
In 1869, Ludwig Valentin Lorenz, as a result of his optical research and his wave equation, developed an equation relating the density of a body and its index of refraction and verified it In the case of water. In 1878, Hendrik Antoon Lorentz, independently, developed the same constant, now known as the Lorentz-Lorenz formula. |
|
In 1869, Elwin Bruno Christoffel, in "Ueber die Transformation
der homogen Differentalausdrücke zweiten Grades," introduced
an operation which transformed one quadratic differential form into
another, i.e., two types of curvature components. This was
a basic question arising from Riemann's geometry and
was later called 'covariant differentiation' by C. Gregorio Ricci-Curbastro (Ehlers 1981:527-542). |
|
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In 1869, Georg Cantor published his proof of the apparent paradox
which stated says that an infinite class has the unique property
that the whole is no greater than some of its parts.
The proof involves acknowledgement that the class of integers is
infinite and countable and, then, establishing a one-to-one correspondence
between the class of integers and its subset, the class of even
numbers. This was the beginning of set theory. The first transfinite
number was created to describe the cardinality of countable infinite
classes. |
|
|
In 1869, Charles Joseph Minard, in a graph showing Napoleon's
march to Moscow and back, set a new standard for such representations
plotting multivariate data: The size of the army, its location on
a two-dimensional surface, its direction, and the temperature on
various dates during the retreat. |
|
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In 1869, John Hyatt produced 'celluloid,' the first synthetic plastic to be put into wide use. |
|
|
In 1870, Gustave Fritsch and Edward Hitzig demonstrated
an inseparable link between electricity and cerebral function, but did not show where the electricity was produced. |
|
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In 1870, Camillo Golgi established that neurons in the braIn sent information to the motor nerves and received it from the sensory
nerves. He developed a silver impregnation method that allowed microscopic visualization of the anatomy of the whole neuron. |
|
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In 1870, Friedrich Goltz suggested that the semicircular canals
of the inner ear are the sense organs that detect the position of
the head relative to to the gravitational field. [added 02/01/03] |
|
|
[The demonstrations of the 1870s and 1880s that the internal processes of cell division were fundamentally the same in plants and animals magnified the cell as a universal unit of structure.] |
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In 1870, William Kingdon Clifford, introducing the details of non-Euclidean geometry to the English, raised the question of "variation
in the curvature of space," describing it as "analogous to little hills on the surface [of the Earth] which is on average
flat," that "the ordinary laws of geometry are not valid in them[, and] that this property of being curved or distorted is
continually being passed on from one portion of space to another after the manner of a wave" (Clifford 1876:21-22). |
|
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In 1871, St. George Mivart, in On the Genesis of Species, claimed that, contrary to Darwin, species arise suddenly
with large-scale changes already intact: Inheritance by blending, as Darwin proposed, meant that variation would have to be sustained
by an extremely high mutation rate. |
|
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In 1871, Darwin, in The Descent of Man, and Selection In Relation to Sex, suggested that there was no sharp discontinuity
between the evolution of humans and animals, that "the difference was one of degree and not of kind" (Darwin 1871:127), and that, therefore, not only was the behavior of animals guided in part by
primitive reasoning processes, but human behavior must also be guided in part by instincts, e.g., the "instinctive tendency to speak" (ibid.:101). |
|
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In 1871, Johann Friedrich Miescher isolated a substance from the nuclei of white blood cells which is soluble in alkalis but
not in acids. This substance came to be called 'nucleic acid.' (Miescher 1871). |
|
In 1871, Maxwell, in Theory of Heat, proposed the idea
that an intelligent being, named by W. Thomson 'Maxwell's
Demon,' could by simple inspection of molecules (i.e., without
doing work) violate the second law. "The demon points
to...the problem of reconciling the irreversible increase in entropy
of the universe demanded by thermodynamics with the dynamical laws
governing the motion of molecules, which reversible with respect
to time" (Everitt 1976:227). Maxwell also introduced
the terms 'vector' and 'scalar potential.' |
|
In 1871, Crookes, in the course of trying to weigh thallium, created a vacuum "on the order of one millionth of an atmosphere
[which] made possible the discovery of X-rays and the electron"
(Brock 1976:475). |
|
In 1871, Strutt, also known as Baron Rayleigh, propounded a
general law relating the intensity of light scattered from small
particles to its wavelength when the dimensions of the particles
are much less than the wavelength. He expressed this scattering
as a function of the inverse fourth power of the wavelength of the
incident light. |
|
|
In 1872, John Thomas Gulick pointed out the inevitability of
divergence among isolated groups even without environmental difference. |
|
|
In 1872, Ludwig and Edward Pfünger showed that oxidation
occurs in tissues, not in the blood. |
|
|
In 1872, Boltzmann, in "Weitere Studien über das Wärmegleichgewicht
unter Gasmolek�len," argued that the second law of thermodynamics, and the spontaneous increase in entropy which it predicts, can only
be understood in terms of large populations of particles, not individual
trajectories, the primitive object of classical physics. Influenced
by Darwin, he replaced the study of individuals "with
the study of populations, and showed that slight variations taking
place over a long period of time can generate evolution at a collective
level" (Prigogine 1996:20; Boltzmann 1905:193-197). Assuming
that all microscopic states of a system have the same probability, he established that entropy was statistical; however, by the same
token he could not establish that long-term deviation from equilibrium
was not impossible, even though very improbable. He
proposed an equation which gives a mathematical description of a
state and how it is changing; i.e., if the Maxwellian E-function
(Boltzmann's H-function) is identical to entropy, then
the definition of entropy can be extended to nonequilibrium states. |
|
|
In 1872, Christian Felix Klein outlined his synthesis of geometric
group transformations, in which he showed that there were three
types of geometry: the Bolyai-Lobachevsky type where
straight lines have two infinitely distant points, the Riemann type where the points are imaginary, and Euclid's
type. The so-called 'Klein bottle,' with no inside, came out of these studies. The best known of his transformations
is the so-called 'Klein four-group,' which was exploited
by the Structuralists after the second world war. |
|
In 1872, Julius Wilhelm Richard Dedekind, in Stetigkeit und
die Irrationalzahlen, maintained that the essence of the continuity
of a line consists in the possibility of dividing that by a single
point, i.e., an irrational number, e.g., a fraction. This
division is known as a Schnitt, or 'Dedekind Cut.'
By putting the points into a one-to-one correspondence with the
rational numbers, a continuum can consist of rational numbers and
the fundamental theorems on limits can be proved rigorously.
Dedekind regarded arithmetic as a "natural consequence of the
simplest arithmetic act, that of counting" (Dedekind 1872:4).
The redefinition of number and limit as ordinal concepts make "calculus...not
a branch of the science of quantity, but of the logic of relations"
(Boyer 1949:294). |
|
|
In 1872, Claude Monet painted "Impression: Sunrise," which has
been used to mark the beginning of Modern Art because it lent its
name to 'Impressionism.' This is a style concerned
with portraying variations in light and color brought on by hour
and season as deduced both from observation and optical principles.
On the other hand, his contemporary, Paul Cézanne simplified
forms to their basic geometric equivalents and was honored as their
master by early abstract painters Henri Matisse and Pablo Picasso. |
|
|
In 1873, Anton Schneider described chromosomes during the process
of mitosis during cell division. |
|
|
In 1873, Moritz Wagner emphasized the effects of different environments
on isolated groups of animals. |
|
|
In 1873 and 1874, Ernst Mach, Breuer, and Alexander Crum
Brown, each independently and each based on Goltz's
1870 suggestion, published the insight that the flow of endolymph
in the canals of the inner ear during motion stimulates the receptors
in the ampullae at the end of the canals. Crum Brown also pointed
out that the two canals received their stimuli from motions in opposite
directions. [added
02/01/03] |
|
|
In 1873, Maxwell, A Treatise on Electricity and Magnetism, tried to finish off the notion of action-at-a-distance and wrote
a summary of his equations in terms of symmetry and vector structure.
This relational Lagrangian method enabled him to forego any mention
of mechanical aether, supposed by many physicists of the time to
be the fundamental electromagnetic substance. Maxwell perceived
that these equations had wave solutions and that electromagnetic
waves of all frequencies were generated by accelerating electric
charges and travelled at the same speed. Moreover, based on
his electromagnetic theory, he established that light exerts a radiation
pressure. This conclusion had many implications (Everitt 1976:212).
He also proposed that these waves could be generated in the laboratory
by creating an quickly oscillating current. |
|
In 1873, Josiah Willard Gibbs, in "Graphical Methods In the Thermodynamics of Fluids," gave the fundamental equation
for entropy, dU = TdS - PdV, where U is the internal
energy, T is the absolute temperature, S is entropy, P is the pressure on the system, and V is its volume. |
|
In 1873, Joseph Antoine Ferdinand Plateau, in Statique expérimentale
et théorique des Liquides soumis aux seules Forces moléculaires, showed experimentally that liquid surfaces always assume a curvature, i.e., the smallest possible area, when there is no appreciable external
force, like gravity, exerted (Adam 1930:1). |
|
|
In 1874, W. Betz extrapolated to the telencephalon the posterior-anterior
sensorimotor dichotomy that prevails along the nerve axis, from
the spinal cord to the brain. |
|
|
In 1874, S. Bodkin published his observation that, in patients
with leukemia, transcutaneous electrical stimulation of the enlarged
spleen led to reduction in size and an increase in leukocyte count. |
|
|
In 1874, Franz Brentano, in Psychologie vom empirischen Standpunkte, maintained that mental processes should be treated as intentional
acts rather than passive processes. Among the auditors of
classes which he taught were Edmund Husserl, Thomas Masaryk, Franz
Kafka, Rudolf Steiner, and Freud. |
|
In 1874, Marie Alfred Cornu described a graphical curve, known
as the 'Cornu spiral,' for calculating light intensities
in Fresnel diffraction. |
|
In 1874, Strutt, in "The Kinetic Theory of the Dissipation
of Energy," pointed out the 'reversibility paradox'
occasioned by Boltzmann's H -function, i.e., the "apparent contradiction between...the reversibility of
individual collisions and the irreversibility predicted by the theorem
itself for a system of many molecules" (Brush 1976:263). |
|
In 1874, Boltzmann, in "Zur Theorie der elastischen Nachwirkung,"
introduced 'memory effects' into the relation between
stresses and strains of an elastic continuum, i.e., "the circumstance
in which a strain that occurred previously reduces the force required
to produce a strain of the same kind" (Boltzmann, quoted In Cercignani 1998:161). This laid the foundations for 'hereditary
mechanics,' a term introduced by E. Picard in 1907. |
|
|
In 1874, William Stanley Jevons, in Principles of Science, demonstrated a symbolic and logical method, intended to supplant Boole and John Venn, that involved permutations of ABC corresponding to the eight compartments of Venn's
three-circle diagram. Jevons also designed labor-saving logic
machines for exploiting his method, among them an 'abacus'
similar to a primitive IBM punchcard machine. |
|
|
In 1875, Richard Caton demonstrated that the brain's electricity
originated in the cerebral cortex. |
|
In 1875, Eduard Seuss coined the term 'biosphere'
for where life can exist, i.e., on the Earth's surface and
adjacent atmosphere. |
|
|
In 1875, Galton demonstrated "the usefulness of twin studies
for elucidating the relative influence of nature (heredity) and
nurture (environment) upon behavioral traits" (King and Stansfield
1997:382). |
|
In 1875, Crookes developed a 'light-mill,' or radiometer.
This is a sealed and evacuated (as far as possible) glass chamber
containing a paddle wheel with vanes blackened on one side and silvered
on the other. This spins rapidly when it is impinged upon
by radiant heat; i.e., "a rise in pressure occurred on the
hotter side of the vanes, which consequently moved away from the
incident radiation" (Brock 1976:480n10). |
|
In 1875, George Henry Lewes, in the second volume of Problems
of Life and Mind, used 'emergent' to describe a 'resultant'
which "arises out of...combined agencies, but in a form which
does not display the agents in action.... The emergent is
unlike its components in so far as...it cannot be reduced either
to their sum or their difference" (Lewes 1875:368-369). |
|
|
In the 1870s, Mach stated the principle that the inertia of
a piece of matter is attributable to the interaction between that
piece of matter and the rest of the Universe, i.e., "a body
in an empty universe has no inertia" (Hiebert 1978:599). This
idea has roots in the writings of Leibniz and was widely
accepted among so-called Energists, e.g., Mayer, who held
the energy was a substance, i.e., matter, and that atoms were only
a convenience (Cercignani 1998:203). [revised
02/01/03] |
|
|
Beginning
in 1876 with anthrax, Robert Koch devised the method of employing
aniline dyes to stain microorganisms. By this means he was able
to isolate pure cultures of bacteria and showed the bacterial origIn of many infectious diseases, including tuberculosis, cholera, bubonic
plague, and sleeping sickness. This confirmed the germ theory of
disease. [revised
02/01/03] |
|
|
In 1876, Wallace published his special contribution to the study
of evolution, The Geography of Animal Distribution. |
|
|
In 1876, Carl Wernicke published a paper in which he described
a new type of aphasia, involving an impairment of comprehension
rather than execution, and located at a different locus from the
aphasia described by Broca. According to Wernicke, interconnections between functional sites make more complex intellectual
functions possible. |
|
|
In 1876, Alexander Graham Bell invented the telephone. |
|
|
In 1876, Nikolas August Otto designed the first four-stroke
piston engine. |
|
|
In 1877, Ernst Abbé published the first in a series of contributions
to the theory of microscopic optics. |
|
In 1877, Maxwell, in "On Boltzmann's Theorem on the
Average Distribution of Energy in a System of Material Points,"
proved that "the densities of the constituent components In a rotating mixture of gases would be the same as if each gas were
present by itself. Hence gaseous mixtures could be separated
by means of a centrifuge" (Everitt 1976:224). |
|
In 1877, Schiaparelli reported detailed observations of Martian
'canali,' or channels. |
|
|
In 1878, F. Heinke published a study on herring, which climaxed
the focus on animal studies. |
|
|
In 1878, Emil Hermann Fischer figured out the chemical formula
for phenylhydrazine, a compound he had discovered. This led to his
research on sugars, of which he synthesized glucose and about thirty
others, purines, of which he synthesized about one hundred thirty, and to the development of synthetic drugs like novacaine. [added
02/01/03] |
|
|
In 1878, Wilhelm Wundt founded the first laboratory devoted
to physiological psychology. He intuited that dreaming is
the product of the simultaneous enhancement and impairment of different
parts of the brain. |
|
In 1878, J. W. Gibbs, in the abstract of "On the Equilibrium
of Heterogenous Substances," asserted that "when the entropy
of a system has reached a maximum, the system will be in a state
of equilibrium" (Gibbs 1878:354). In the paper itself, published in two parts, in 1876 and 1878, he proceeded to generalize
thermodynamic equilibrium theory, removing one restriction after
another, and deriving, for example, the chemical phase rule: "In a heterogenous system composed of several homogenous phases, the
fundamental equilibrium condition leads to the requirement that
temperature, pressure, and the chemical potential of each independent
chemical component must have the same values throughout the system"
(Klein 1976:390). Other experimental facts, "such as
the theories of catalysis, of solid solutions, and of the actions
of semi-permeable diaphragms and osmotic pressure, [he] showed...are
in fact simple, direct and necessary consequences of the fundamental
laws of thermodynamics" (Bumstead 1903:xviii). He also
defined what has came to be known as 'Gibb's function,'
or 'free energy,' a measure of a system's ability
to do work; i.e., that portion of the total energy "which can
be freely converted to other forms of energy.... In any spontaneous
reaction occurring at a constant temperature and volume the free
energy must decrease. Hence the free energy, not the total
energy change measured by the evolution of heat, determines the
direction of any reaction" (Turner 1976:244). |
|
In 1878, Maxwell, in "On Stresses in Rarefied Gases Arising
From Inequalities of Temperature," explaining the action of
a radiometer, noted that "when a viscous fluid moves past a
solid body, it generates tangential stresses by sliding [i.e., 'slip'
effects] over the surface with a finite velocity" (Everitt
1976:224). Indepenently, Osbourne Reynolds came to
a similar conclusion about the same time. |
|
|
In 1879, Walther Flemming named 'chromatin' and 'mitosis,'
made the first accurate counts of chromosome numbers,and discerned
the longitudinal splitting of chromosomes. |
|
In 1879, Crookes, in "On the Illumination of Lines of Molecular
Pressure, and the Trajectory of Molecules," attempted to determine
the paths of the 'lines of molecular pressure,' or cathode
rays, in an evacuated glass tube through which two electrodes are
passed. When high voltage is applied, electrons are emitted
from the radiometer vanes, which act as a cathode, and, under reduced
pressure, the vane turns and the electrons are accelerated toward
the anode. Many of these electrons, or cathode rays, miss
the anode and, striking the tube wall, exhibit fluorescence. |
|
|
In 1879, Jules-Henri Poincaré showed how automorphic functions
can be used to express coordinates of any point in an algebraic
curve as uniform functions of a single parameter. |
|
In 1879, Stefan, in "åber die Beziehung zwischen der
Wärmestrahlung," conjectured that that the radiant energy
emitted by an enclosure equivalent to a black body is proportional
to the fourth power of the body's temperature. |
|
|
In 1879, Planck, in Vorlesungen über Thermodynamik, opposed the idea that the validity of the second law depends upon
the existence of an observer or his lack of information. The
implication is that irreversibility is natural. |
|
|
In 1879, Albert Abraham Michelson determined the speed of light
to be 186,350 miles per second + or - 30 miles per second. |
|
|
In 1879, Edwin Herbert Hall discovered a component of an electric
field which when crossed with a magnetic field becomes perpendicular
to the electric field. Known as 'Hall current,' or
the 'Hall effect,' it was not explained until the advent
of quantum theory. |
|
|
In 1879, Gottlob Frege, in Begriffsschrift, proffered
the first system of propositional calculus, also known as the calculus
of sentential conjunctions. |
|
|
In 1880, Sydney Ringer studied the use of body temperature In diagnosis and inorganic ions in heart contractions, making possible
the analysis of heart metabolism. |
|
|
In 1881, Wallace proposed to date the beginning of the Cambrian period about 28 million years ago. |
|
|
In 1881, Lucian Galard and John D. Gibbs obtained patents for systems of alternating electrical current. |
|
|
In 1881, Venn, in Symbolic Logic, represented logical
propositions diagrammatically. |
|
|
In 1882, Eduard Strasburger coined the terms 'cytoplasm'
and 'nucleoplasm.' |
|
|
In 1882, Dmitri Iosefovich Ivanovsky demonstrated that tobacco
mosaic disease is caused by "a self-replicating agent (or virus)
that will pass through bacterial filters and can neither be seen
with light microscope nor grown upon bacteriological media"
(King and Stansfield 1997:382). |
|
In 1882, Helmholtz, independently of Gibbs, distinguished
between 'bound' and 'free energy' in chemical
reactions, the formula for which, free energy equals internal energy
minus the temperature of the system times its entropy, is known
as the Gibbs-Helmholtz equation. |
|
In 1882, Michelson described an 'interferometer,' an
interference meter, which had a half-silvered mirror in order to
split incident beams of light into two parts at right angles to
each other. |
|
|
In 1883, Ilia Il'ich, also known as Élie, Metchnikoff identified
the phagocyte as a purveyor of cellular defense, thereby raising
questions of organismic identity, i.e., how do organisms protect
themselves from their environment? He recognized that phagocytes, cells capable of engulfing particles, such as bacteria, define the
'self' constituents; that is, they devour tadpole tails
as frogs metamorphosize into adults. Viewing the immune system
as "self-referential, not antigen-driven," he saw inflammation as
"self-directed 'immune' surveillance" (Tauber 1990:566).
This biological line of investigation developed into 'humoral
theory,' after the classic term for body fluids, and was driven
by the need to understand what identified non-host elements. It
may be noted that bloodletting did not go out of fashion until about
this time. |
|
|
In 1883, Edouard van Beneden, studying nuclear division in the
germ cells of a round worm, explained the "longstanding paradox
that the maternal and paternal contributions to the character of
the progeny seem often to be equal, despite the enormous difference
in size between the egg and the sperm" (Alberts et al. 1994:1014). This explanation was made possible by his discovery
that, while gamete nuclei, i.e., the sperm and egg nuclei, each
have two chromosomes, the fertilized egg has four chromosomes. This
implies that chromosomes carry genetic information and that germ
cells, in contrast to somatic cells, must undergo a special sort
of nuclear division in which the chromosome complement is halved.
This process came to be known as 'meiosis,' a word which
means that something appears to be of less size or significance
than it really is. [revised
02/01/03] |
|
|
In 1883, Weismann stated that his 'germ-line theory,'
namely, that the separation of the germ-line from the phenotype
of the body, or soma, is final from the point in the egg's development
when it is determined which cells will become the ovary or the testes--and
potentially immortal. In human beings, for example, this point
occurs at the 59th day of gestation. This doctrine refuted Lamarck's theory that acquired characters can be inherited.
It also made it possible to understand the genetics of animals (though
not plants), and, hence, evolution without understanding development. |
|
|
In 1883, Max Rubner said that a body's metabolic rate was
proportional to its surface area. |
|
|
In 1883, Oscar Hertwig described 'mesenchyme,' a term
he coined for the protoplasmic network filled with a intercellular
fluid which gives rise to connective and other tissue. |
|
|
In 1883, Wilhelm Roux suggested that the filaments within the
cell's nucleus carry the hereditary factors. |
|
|
In 1883, Karl Georg Friedrich Rudolf Leuckart and A. P. Thomas, independently, working on the life cycle of sheep liver flukes, determined the snails were intermediate hosts. |
|
|
In 1883, Galton advocated selective breeding of human beings, or 'eugenics,' which he coined from a Greek word meaning
"hereditarily endowed with noble qualities" (Galton 1883:24).
Eugenics was discredited through the uses to which it was put, especially
during the 1930s and 1940s. |
|
|
In 1883, George John Romanes published Mental Evolution In Animals, the first modern text comparing the psychology of humans
and animals in objective terms. |
|
|
In I883, Jean-Martin Charcot was able to obtain recognition
of the neurological reality of hypnotism from the French Academy
of Sciences. He thought only hysterics were susceptible to
hypnosis, i.e., that hypnosis was itself a pathological condition. |
|
|
In 1883, Pierre Curie discovered piezoelectricity, a form of
electric polarity, in crystals. |
|
|
In 1883, Mach, in Die Mechanik in ihrer Entwicklung, translated as The Science of Mechanics: A Critical and Historical
Account of Its Development, attempted to eliminate metaphysics
by reducing science to the sum of what appears to the senses, and, in particular, attacked Newton's assumption that absolute
rotation is observable. "The object of science [is] to replace, or save experiences, by the reproduction and anticipation
of facts in thought...; [but] we never reproduce the facts in full..., only that side of them which is important to us, moved directly
or indirectly by practical interest" (Mach 1883:481-482).
Concepts both compete for adherents and adapt to facts and to one
another in order to survive. Mach also did work in the field
of ballistics, where the 'Mach number' borrows his name. |
|
In 1883, Boltzmann, in "Ableitung des Stefan'schen
Gesetzes," based on the fact that electromagnetic waves exert
pressure on the walls of a radiation-filled enclosure, worked out
theoretically a relation between thermodynamics and Maxwell's
electromagnetic equations, i.e., the fourth power law previously
found experimentally by Stefan. |
|
|
In 1883, Reynolds introduced the 'Reynolds' number,'
a dimensionless quantity associated with the smoothness of the flow
of a fluid, which characterizes laminar and turbulent flow by relating
kinetic to viscous forces. |
|
|
In 1883, Gottlieb Daimler patented the gasoline combustion engine. |
|
|
In 1884, A. Kossel isolated a protein from the nuclei of goose
erythrocytes and called them 'histones.' |
|
|
In 1884, Julius Kollman described the phenomena of 'neoteny'
in his study of the axolotl form of Ambystoma tigrinum. |
|
|
In 1884, J. Hughlings Jackson published his speculation that
the neuropathological dissolution of function tends to roughly reverse
the order of the acquisition of that function. |
|
|
In 1884, Freud published a paper in which he found cocaine, an alkaloid in coca, effective against fatigue and neurasthenia. |
|
|
In 1884, Jacobus Hendricus van't Hoff explained the principle
of equilibrium in chemical dynamics and osmotic electrical conductivity. |
|
|
In 1884, Edwin A. Abbott, in Flatland: A Romance of Many
Dimensions, recounted the adventures of 'A. Square,'
a character who inhabits a two-dimensional world populated by other
geometrical figures--triangles, squares, pentagons, hexagons, etc.
Toward the end of the story, on the first day of 2000, a spherical
creature from 'Spaceland' carries A. Square off to show
him the three-dimensional nature of the larger world. There
A. Square speculates that Spaceland may itself exist as a subspace
of a larger four-dimensional universe, an "infallible confirmation
of the series [of end-points of a line, a square, a cube, etc.], 2, 4, 8, 16" (Abbott 1884:on line). |
|
|
In 1884, Hilaire de Chardonnet invented the first artificial
textile, which was made from cellulose. It was later named
rayon. |
|
|
By
1885, Hertwig and Strasburger developed the conception
that the nucleus is the basis of heredity. Subsequently, Hertwig
asserted that from the biological point of view sex is merely the
union of two cells. |
|
|
In 1885, Roux, testing Weismann's idea of heredity
and germ plasm, did one of the first experiments in what became
experimental embryology when he showed that embryonic chick cells
could be maintained alive in a saline solution. |
|
In 1885, Ernst Hartwig noticed a nova in the Andromeda nebulae. Before it faded, he noted its peak intensity which
was as great as the rest of the galaxy combined. |
|
|
In 1885, Friedrich Wilhelm Nietzsche completed Also sprach
Zarathustra in which he created the term 'id,' meaning
the resevoir of human instinctual drives. Other psychological
terms employed frequently in his writings include sublimation and
inhibition. |
|
|
In 1886, Hippolyte Bernheim published his argument that hypnotism
was a special case of general human suggestibility; i.e., anyone
could be hypnotized. |
|
|
[In the course of the nineteenth century, the practice of hypnotism
brought with it greater popular, as well as medical, awareness of
the split between conscious and unconscious behavior, as may be
seen in the stories of E. T. A. Hoffman, E. A. Poe, Honoré
de Balzac, Alexander Dumas, Victor Hugo, R. L. Stevenson, Fyodor
Dostoevsky, and others (Ellenberger 1970:158-170). Greater
experience with hypnotism also brought disillusion with its limitations, e.g., sensitized patients confirming their doctor's unspoken expectations, etc.]. |
|
|
In 1886, Pierre Janet, in L'Automatisme Psychologique, introduced the term 'subconscious' in the context of patients'
fixed ideas. |
|
|
In 1886, Richard von Krafft-Ebing, in Psychopathia Sexualis, included among his classifications the terms 'sadism' (after
Donatien de Sade) and 'masochism' (after Leopold Sacher-Masoch). |
|
|
In 1887, Wilhelm His , in "Zur Geschichte des menschlichen
Rückenmarkes und der Nervenwurzeln," published his discovery
that in the early stages of development the nervous system is made
up of independent, closely packed cells without axons. |
|
|
In 1887, Auguste Forel showed that certain degenerative effects
remained limited to the cell body and its dendrites. |
|
|
In 1887, Svante August Arrhenius announced the theory of electrolytic
dissociation which says that in aqueous solution the molecules of
all acids, bases, and salts are split into ions. This theory
depends on van't Hoff's equilibrium principle. |
|
|
In 1887, Michelson and Edward W. Morley, using an interferometer
to investigate whether the speed of light depends on the direction
the light beam moves, failed to detect the motion of the Earth with
respect to the aether, thereby refuting the hypothesis that the
aether exists. |
|
|
In 1887, Heinrich Rudolf Hertz produced Maxwellian electromagnetic
waves, the first radio waves. He demonstrated that they travel
at the velocity of light and can be reflected, refracted, and polarized
like light. They also led him to drop Helmholtz's action-at-a-distance
point of view. The unit of frequency was named in his honor. |
|
|
In 1888, Roux removed from a frog's egg one of the two cells
existing after the first cleavage and obtained a half embryo. |
|
|
In 1888, Santiago Ramón y Cajal, employing Golgi's
staining technique, launched attacks on the 'nerve-net hypothesis'
by demonstrating the anatomical independence of the axon from its
target cell, i.e., that neurons are juxtaposed, not continuous.
At the time it was not realized that nerve cells do not interact
through cell bodies, but through their axons and dendrites.
This permitted two hypotheses: that of the nerve-net or continuous
network and that of the neuron or contiguous, but independent cells.
This question was not settled until the increased resolving power
of electron microscopy after 1950. |
|
|
In 1888, George Henry Falkiner Nuttall showed the blood serum
contained bactericidal substances, from which he concluded that
phagocytes were merely accessory to the protection offered by serum. |
|
|
In 1888, Heinrich Wilhelm Gottfried Waldeyer named Roux's
filaments 'chromosomes.' |
|
|
In 1888, Theodore Boveri described the 'centriole' which
in animals and most plants lies just outside a cell's nucleus. |
|
Between
1888 and 1893, Marius Sophus Lie and Friedrich Engel published the six volumes of Theorie der Transformationsgruppen in which they showed that different sorts of symmetry form mathematical
groups. Lie divided these groups into "deux grandes classes:
les groups intégrables et les groupes non intégrables"
(Cartan 1894:103). |
|
|
In 1888, Nicola Tesla patented his invention of alternating
electric current. |
|
|
In the late 1880s, Louis Lewin and Arthur Heffter isolated
the peyote alkaloid, mezcal. |
|
|
In 1889, Wallace published his book on natural selection, which
he called Darwinism. |
|
|
In 1889, George Francis FitzGerald, in "The Ether and the
Earth's Atmosphere," suggested that the null results of
the Michelson-Morley experiment could be explained by the
shrinkage of a body due to motion at speeds close to that of light, and that the only assumption necessary is that intermolecular forces
obey the same laws as electromagnetic forces (FitzGerald 1889:390).
In 1892, Lorentz, independently, reached the same conclusions
about the contraction of a moving body. |
|
|
In 1889, Giuseppe Peano postulated five properties of natural
numbers in attempting to be as rigorous with numbers as Euclid had been with geometry. |
|
|
In 1890, Boveri and Jean Louis Guignand established the
numerical equality of paternal and maternal chromosomes at fertilization. |
|
|
In 1890, Hans Driesch separated two cells of a fertized sea
urchin egg by shaking with very different results than Roux:
From a single cell arose an entire sea urchin. Roux's
frog experiment was repeated and by merely turning the cell over
it developed into a whole frog. Thus, a cell's competence
to develop fully was established. Roux was not deterred by
this result and continued to maintain, against Weismann's germ-line theory, that the mechanics of development were distributed
throughout the cytoplasm and triggered by each prior stage. |
|
|
In 1890, Richard Altmann reported the presence within cells
of organisms which live as intracellular symbionts, and were later
named mitochondria. |
|
|
In 1890, Emil Adoph von Behring and Shibasaburo Kitasato showed that antitoxins, that is, antibodies, could be produced--without
any knowledge of their chemical nature--which neutralized the soluble
toxins, classically, diptheria, tetanus, and botulism. |
|
|
In 1890, Theobold Smith demonstrated the transmission of disease
by an 'arthropod vector,' a tick. |
|
|
In 1890, William James, in Principles of Psychology, accepted the idea that all behavior derives from the nervous system.
He also suggested that learning is accompanied by an increase In neuronal efficiency, and that primary memory, or short-term memory, is memory of the immediate past still in consciousness where it
is the object of selective attention. |
|
|
In 1890, Eugen Bleuler declared that 'dementia praecox'
was curable. |
|
In 1890, Michaelson, in "On the Application of Interference
Methods to Astronomical Measurements," described the utility
of interferometers "in measuring the angular size and the one-dimensional
brightness distribution of sources that are too small to be resolved
by a single telescope" (Lang and Gingerich 1979:2). |
|
|
Before
1890, Herman Hollerith invented a punch card tabulator which
was used in the United States Census of 1890. Hollerith's company
eventually became IBM. |
|
In the 1890s, William Coley observed that some of his cancer
patients were able to eliminate their cancer after contracting severe
bacterial infections and so causing him to use bacterial extracts
to activate the immune system with some good results. |
|
|
In 1891, Marie Eugene Dubois discovered 'Javaman,' now
known as Homo erectus. |
|
|
In 1891, Waldeyer named nerve cells 'neurons.'. |
|
|
In 1891, George Redmayne Murray successfully treated hypothyroid
patients with a preparation of sheep thyroid. |
|
|
In 1892, Poincaré published the first of three volumes
on celestial mechanics in which he made fundamental mathematical
discoveries, such as his demonstration that dynamical systems are
non-integrable, i.e., they are neither static nor deterministic.
He also identified the reason for this, which is the existence of
resonances between the degrees of freedom of, e.g., harmonic oscillators.
His memoirs on 'analysis situs,' as it was then called, marked the beginning of modern topology. |
|
|
In 1892, Lorentz, in "La théorie électromagnétique
de Maxwell et son application aux corps mouvants," proposed
a theory of 'charged particles,' in which a body carries
a charge if it has an excess of positive or negative particles, an electric current in a conductor is a flow of particulate particles, and the particles create the electromagnetic field. "Because
Lorentz completely separated ether [i.e., the field] and matter, he needed only one pair of directed magnitudes-one electric and
one magnetic-to define the field at a point" (McCormmach 1976:494).
He also derived Fresnel's 'drag coefficient,'
the measure of the motion that a moving transparent body communicates
to light passing through it, and demonstrated that the drag was
the result of the interference of light. |
|
|
In 1893, Andreas Franz Wilhelm Schimper proposed the idea that
the photosynthetic parts of plant cells came from cyanobacteria. |
|
|
In 1893, Freud and Breuer published Über den
Psychischen Mechanismus Hysterischer, marking the beginning
of psychoanalysis. They claimed that "hysterics suffer mainly
from reminescences" (Breuer and Freud 1893:7). |
|
|
In 1893, Michaelson completed the measurement of the standard
meter in terms of the wave length of the red line of the cadmium
spectrum, providing an absolute and reproducible standard. |
|
|
In 1893, Emile Durkheim published the first of a series of sociological
books in which he explained how the ostensible explanations of theistic
world-views, e.g., curiosity about the seasons or the rest of the
natural environment, are actually "phrased so as to satisfy a dominant
social concern, the problem of how to organize together in society"
(Douglas 1966:91). |
|
|
In 1894, William Bateson, in Materials for the Study of Variation, emphasized the importance of discontinuous variations and described
and named homeotic mutations. |
|
|
In 1894, H. J. H. Fenton discovered a reaction, to which he
lent his name, now considered to be one of the most important mechanisms
of oxidative damage in living cells. |
|
|
In 1894, Ramón y Cajal, combining and extending the ideas
of E. Tanzi and E. Lugaro, proposed the plastic, or
functional, change hypothesis for neuronal growth, according to
which synapses on 'associative pathways' are able to strengthen
through use and to make new associations through learning. |
|
|
In 1894, George Oliver and Eduard Albert Sharpey-Schaeffer demonstrated the effect of an extract of the adrenal gland, that
is to say, a hormone, which contracted blood vessels and muscles
and raised blood pressure. |
|
|
In 1894, Emil Fischer suggested that a cell contains a chemically
active substance whose geometrical configuration is complementary
to that of another substance, fitting it like a key in a lock (Fischer
1894; de Duve 1991:22n8). These studies still form the basis
of our notions of enzyme specificity. |
|
|
[["From
the time of [N.] Carnot on, when it was discovered that the
new science of thermodynamics did not require any sort of picture
or model to explain the nature of heat, there had been a widespread
hostile attitude among Continental physicists [Mach is one
example] to any form of hypothetical model in science. By
[the time of Boltzmann, Planck, and Hertz], however, new developments in physics were requiring fresh patterns
of explanation, and these warranted complex mechanical hypotheses"
(Janik and Toulmin 1973:143)]]. |
|
|
In 1894, Hertz, in Principien der Mechanik, having earlier
held that "Maxwell's theory is in Maxwell's
equations" (Hertz, quoted in McCormmach 1976:346), noted that
mathematical formulas could confer a logical structure on physical
reality, creating 'possible sequences' of observed events.
Hertz opened Principien with the statement that "all
physicists agree that the problem of physics consists in tracing
the phenomena of nature back to the simple laws of mechanics"
(Ibid.:348). He went on to trace the classic mechanical
formulations of Newton, Lagrange, and Hamilton, but it was one of the last times anyone would make that statement. |
|
|
In 1894, Strutt and William Ramsay discovered and isolated
argon in the process of explaining the discrepancy between the weight
of nitrogen obtained from the air and from ammonia. |
|
In 1894, Élie Joseph Cartan, in "Sur la Structure des
Groupe de Transformations Finis et Continus," laid out all possible
variations of Lie groups and gave them names, e.g., U(1), or unitary group with one matrix row, or SU(2), or special unitary
group with two matrix rows (Cartan 1894:133-287). |
|
|
In 1894, Oliver Joseph Lodge invented the 'coherer,'
a detector used in early radio receivers. |
|
|
In 1895, Richard F. J. Pfeiffer presented the theory that bactericidal
substances in the blood, or "Antikörper," were "highly active"
and "were formed 'under the influence' of the body's
cells and were consumed in the process of destroying bacteria" (Keating
and Ousman 1991:248). |
|
|
In 1895, Smith produced a blood deficiency disease in guinea
pigs by depriving them of leafy vegetables. |
|
|
In 1895, Johannes Eugenius Bülow Warming, in Plantesamfund (which was translated as The Ecology of Plants in 1909), plotted the distribution of plants against temperature and moisture. |
|
In 1895, Wilhelm Conrad Röntgen, using a Crookes'
tube, observed a new form of penetrating radiation, which he named
X-rays. |
|
In 1895, Lorentz, in Versuch einer Theoris der electrischen
und optischen Erscheinungen in bewegten Körpen, spoke of
'ions,' instead of charged particles, and produced an
equation connecting the continuous field with discrete electricity. |
|
|
In 1895, Guglielmo Marconi sent longwave wireless telegraphic, or radio, signals over a distance of more than a mile. |
|
|
In 1896, Romanes promulgated the notion that behavior is species-dependent
and phyletic, or inherited. He also coined the term 'Neo-Darwinism'
in order to differentiate pre- and post-Weismannian concepts of
evolution. |
|
|
In 1896, Conwy Lloyd Morgan, James Mark Baldwin, and
Henry Fairfield Osborn, each independently, proposed a theory
of how acquired characters could be inherited. Lloyd Morgan
concluded that evolutionary changes in anatomy can give rise to
new behavior patterns. Baldwin named his version 'Organic
Selection' "since it required the direct cooperation of the
organism itself." The idea behind this so-called 'BaldwIn effect' is that learning creates habituation which, in turn, provides the adaptive occasion for selection, or "overproduction
with survival of the fittest" (Baldwin 1896:546,548-549). |
|
|
In 1896, Ferdinand Isidore Widal introduced serological diagnosis
through his discovery that typhoid patients agglutinate typhoid
bacilli. |
|
|
In 1896, Eduard Buchner discovered a chemical in yeast, which
he called zymase. He noted that the crushed yeast, that is, cell-free yeast, fermented sugar. This observation
opened the era of modern biochemistry. |
|
|
In 1896, Freud suggested analyzing childhood conflicts in the
study of neuroses. He also devised a psychoanalytic technique
called 'free association' which allows emotionally-charged, repressed material to be consciously recognized. Over the
next few years, Freud expanded his interpretive repertoire to include
"dreams..., slips of the tongue, bungled actions, the forgetting
of names, and what he called 'screen memories' (vivid but
essentially counterfeit recollections from childhood)" (Kerr 1993:76). |
|
|
In 1896, Pieter Zeeman observed that a single spectral line
splits into a group of closely spaced lines when the substance producing
the line is subjected to a uniform magnetic field. This is
known as the 'Zeeman effect,' and was explained by Lorentz on the basis of his electron theory. |
|
|
In 1896, Antoine Henri Becquerel discovered radioactivity In uranium. |
|
In 1896, Boltzmann, in Vorlesunfer über Gastheorie, provided what he felt was a reasonable basis for statistical mechanics:
"We...obtain the correct average values if we consider...an
infinite number of equivalent systems, which started from arbitrary
initial conditions" (Boltzmann 1896:310). These mean
values he called the 'Ergoden,' or "the so-called
'quasi-ergotic hypothesis, [i.e.,] the trajectory of a [kinetic]
system may pass arbitrarily close to every point on an energy
surface" (Brush 1964:11). |
|
|
In 1897, Paul Ehrlich , in Die Wertbemessung des Diphtherieheilserums
und deren theoretische Grundlagen,determined that a toxin was
toxic because it had a chemical, i.e., molecular receptor, structure
complementary to the molecular structure of the susceptible cell.
If there were no matching receptors, this meant there was no disease.
If there were some matches, but the cell did not have enough receptors
to deal with all the toxins, the cell would produce more and release
them into the blood (Ehrlich 1897). This was the first selective
theory of antibody formation. By 1900, he had revised this theory
to mintain that antibodies were continuously formed under normal
conditions. |
|
|
In 1897, Charles Sherrington named the junction between the
neurons, a 'synapse.' |
|
|
In 1897, Christiaan Eijkman proved that in a rice diet only
rice with hulls intact would prevent 'beriberi.' |
|
|
In 1897, Gabriel Bertrand designated certain inorganic substances
co-enzymes because they were necessary to activate certain enzymes. |
|
|
In 1897, Felix Hoffman synthesized a form of acetysalicylic
acid that enabled the mass production of aspirin two years later. |
|
|
In 1897, Jean Henri Fabre observed a series of stereotypic sequences
in insect behavior, later named 'fixed-action patterns'
by Konrad Lorenz. |
|
In 1897, Wilhelm Fliess suggested that all organisms were fundamentally
bisexual, with the implication that adolescence is as much a time
of sexual repression as of sexual flowering. |
|
|
In 1897, Joseph John Thomson, using a Crookes' tube, demonstrated that cathode rays consisted of units of electrical
current made up of negatively charged particles of subatomic size.
Believing them to be integral to all matter, in "Cathode Rays,"
he hypothesized a model of atomic structure in which negatively
charged particles, or electrons, were embedded in a sphere of positive
electricity. (Thomson 1897) |
|
In 1897, Boltzmann, responding to Ernst Zermelo on time
irreversibility, preferred a "universe, which is in thermal
equilibrium as a whole and therefore dead, [but has] here and there
relatively small regions the size of our galaxy..., which during
the relatively short time of aeons deviate significantly from thermal
equilibrium," i.e., corresponding to the existence of life, to an entire universe of "unidirectional change...from a definite
initial state to final state" (Boltzmann, quoted in Cercignani
1998:102). Earlier, to the same end, he had maintained that
"the probability that such a small part of [the universe] as
our world should be in its present state is no longer small"
(Boltzmann 1895:415). |
|
In 1897, Jacobus Cornelius Kapteyn, in a program of measuring
the proper motions of stars, found two preferred directions of motion, roughly toward and away from the center of our Galaxy. This
is known as 'star streaming.' |
|
|
In 1897, Peirce attempted to publish a topographical system
of symbolic logic which he belived could give geometric expression
to any conceivable assertion or logical argument. "Once a
formal structure had been adequately graphed, it could then be experimented
upon in a manner similar to the way a scientist experiments with
a structure in nature" (Gardner 1982:56). |
|
|
In 1898, Henry Fairfield Osborne enunciated the evolutionary
concept of 'adaptive radiation,' the descent from an ancestral
form of related species occupying and exploiting different types
of available habitats. |
|
In 1898, Edward L. Thorndike devised the first reliable techniques
for measuring learning in animals. |
|
In 1898, Golgi described the 'Golgi apparatus.' [added
02/01/03] |
|
|
In 1898, Stokes suggested that X-rays were pulses of radiation
emitted when electrons, ejected from a cathode, hit a target. |
|
|
In 1898, Marie Sklodowska Curie and P. Curie discovered
and isolated radium and polonium. and clarified that radiation was
an atomic property. M. Curie coined the term 'radioactive.' |
|
|
In 1898, J. Thomson, in "On the Charge of Electricity Carried
by the Ions Produced by Röntgen-Rays," showed that neon
gas consisted of two types of charged electrons, or ions, each with
a different charge, or mass, or both. This raised the possibility
that varieties of a single element might exist with the same atomic
number but differ in mass. |
|
In 1898, Planck, in "Über irreversible Strahlungsvorg�nge.
Vierte Mitteilung" and probably responding to Boltzmann's
criticism, adopted the kinetic theory and changed his program completely, saying that "all the radiation processes which do not exhibit
the feature of irreversibility" must be excluded (Planck, quoted
in Cercignani 1976:218). |
|
|
In 1898, Wien, while studying streams of ionized gas, identified
a positive particle equal in mass to the hydrogen atom, which later
was named the 'proton.' |
|
In 1898, Poincaré, in "De la mesure du temps,"
postulated the limiting and constant speed of light and formulated
the principle of relativity non-mathematically. |
|
In 1898, George Johnstone Stoney showed that the stability of
the atmosphere of a given planet depends on its temperature and
its mass. If the velocity of individual molecules, as determined
by their temperature, exceed the planet's 'escape velocity,' as
determined by its gravitational pull, the lighter molecules are
more likely to escape. |
|
|
In 1898, Ramsey and Morris Travers discovered neon, krypton, and xenon. |
|
|
In 1898, James Dewar liquified hydrogen. |
|
|
In 1899, Charles O. Whitman , working with pigeons, and Oskar Heinroth, working with ducks, independently discovered that
the stereotypic responses of birds could be used as a taxonomic
criteria for phylogenetic classification. |
|
|
In 1899, the sixth edition of Emil Kraepelin's textbook, Psychiatrie, codified a diagnostic distinction, based on
outcome statistics, by adding dementia praecox, i.e., 'schizophrenia,'
to 'manic-depression' and 'paranoia.' |
|
|
In 1899, Ernest Rutherford characterized the radiation from
radium as being quite complex, easily absorbed, and stopped by a
few centimeters of air. These he named 'alpha rays.'
He also characterized uranium radiation as far more penetrating.
These he named 'beta rays.' |
|
|
In 1899, Becquerel showed that radioactivity in uranium consists
in charged particles that are deflected by a magnetic field. |
|
In 1899, Strutt, in "On the Transmission of Light Through
an Atmosphere Containing Small Particles in Suspension, and On the
Origin of the Blue of the Sky," explained 'elastic scattering
of electromagnetic radiation,' called 'Rayleigh scattering,'
as reflected photons, i.e., photons which bounce off atoms and molecules
without any change of energy. Therefore, for example, the
'elastic scattering' of photons when they bounce off molecules
and atoms in the Earth's atmosphere accounts for the color of
the sky and red sunsets. |
|
In 1899, J. Thomson, in "On the Masses of Ions in Gases
at Low Pressure," pointed out that ions have "a very much
smaller mass than ordinary atoms; so that in the convection of negative
electricity...we have...something which involves the splitting up
of the atom" (Thomson 1899:548). |
|
In 1899, Lorentz, in "Théorie simplifiée des
phénomènes électriques et optique dans des corps
en mouvement," treated his contraction hypothesis mathematically
in terms of electrons and, except for not determining the coefficient
and not generalizing the subject to any mass, the resulting transformations
for space and time coordinates are the same as those in his 1904
article. |
|
In 1899, Thomas Chrowder Chamberlain raised the question of
whether the "present knowledge relative to the behavior of matter
under such extraordinary conditions as obtain in the interior of
the sun [is] sufficiently exhaustive to warrent the assertion that
no unrecognized sources of heat reside there? What the internal
constitution of atoms may be is yet open to question. It is
not improbable that they are complex organizations and seats of
enormous energies" (Chamberlain 1899:12). ChamberlaIn was a geologist and "up to the end of the nineteenth century, the minimum estimates of geologists were far in excess of the maximum
which physicists would allow for the age of the solar system on
the basis of known sources of energy radiated by the sun.
When the enormously greater energy from the conversion of mass became
known, there was no difficulty in reconciling estimates" (Wright
1948:920). |
|
|
In 1900, Julius Bernstein hypothesized that nerve cells have
both a resting and a stimulated potential. During the resting potential, the cell is impermeable to the negatively charged ions. When the
cell is stimulated, the ions can pass in both directions (BernsteIn 1902). [revised
02/01/03] |
|
|
In 1900, the significance of Mendel's work was realized
when there were three independent accounts of it by Hugo Marie de
Vries, Carl Erich Correns, and Erich von Tschermak von Seysegegg. |
|
|
In 1900, Karl Pearson developed the chi-square, or c2,
test, a statistical procedure that enables the determination of how closely
an experimental set of values conforms to theoretical expectation. |
|
|
In 1900, Mikhail Semenovich Tsvet, or sometimes Tswett, established
that in leaves there are two green pigments, chlorophyll a and b, differing in color, fluorescence, and spectral absorption.
Subsequently he discerned another green pigment, chlorophyll c. [added
02/01/03] |
|
|
In 1900, Planck, in "Zur Theorie des Gesetzes der Enieverteilung
im Normalspektrum," introduced the 'quantum theory'
to explain a formula, E=hf, where E is energy, f is frequency, and h is a new constant, 6.63 x 10-34 J-sec., which accounts for experimental data in black-body radiation. Quantum is a Latin word, widely used in German to mean 'portion.'.
This theory holds that oscillating atoms absorb and emit energy, or light, only in discrete bundles, or 'quanta,' rather
than continuously, as classical physics would have it. Each quanta
has a value proportional to the frequency of the oscillation. |
|
In 1900, Joseph Larmor, in Aether and Matter, showed
that Maxwell's theory of the electromagnetic field can
be derived from a Lagrangian, which equals the square of the magnetic
field strength H2 minus the square of the electric
field E2. |
|
In 1900, Rutherford identified a third type of radiation, which
he called 'gamma radiation.' Rather than consisting of particles, like alpha and beta radiation, gamma rays are electromagnetic photons. |
|
|
In 1901, de Vries devoted his book, in Die Mutationstheorie, promulgated the principle characters, or genes, and the speculation
that that made possible, namely, evolution of species by discontinuities, or 'saltations,' rather than by imperceptible gradations.
This led to Darwin's eclipse for some years, at least, for those biologists who believed with de Vries that mutation superceded
selection as the cause of evolution. |
|
|
In 1901, Richard Bucke proposed the possibility of man's
evolution from self-consciousness to 'cosmic consciousness.' |
|
|
In 1901, Josiah Royce contended that "the distinction between
Self and the not-Self had a predominently social origin"
(Royce 1901:245). |
|
|
In 1901, Planck discovered the first indications of the granular
structure of electromagnetic radiation while working on the spectrum
of blackbody radiation. |
|
|
In 1901, Oliver Heaviside and, independently, Arthur E. Kennelly predicted the existence of an atmospheric layer, later named the
ionosphere, that would reflect radio waves. This encouraged Marconi, the following year, to make a successful attempt
to send radio signals across the Atlantic ocean. |
|
In 1901, Ricci-Curbastro and Tullio Levi-Civita, in Méthodes
de calcul différentiel absolu et leurs applications, developed
a coordinate-free tensor calculus using Christoffel's
symbols. |
|
In 1901, Willis H. Carrier invented the industrial air conditioner. |
|
|
In 1902, W. Bateson, in Mendel's Principles of Heredity:
A Defense, in which he demonstrated that Mendel's principles apply also to animals. In the same year, he coined
'allomorph,' and, before 1909, also 'genetics,'
'homozygote,' 'heterozygote,' and 'epistatic.' |
|
|
By
1902, Karl Landsteiner found that human blood was one of
four types, A, B, A-B, and O, thus making transfusions safe. |
|
In 1902, E. Overton supported Bernstein's idea with evidence
that exogamous sodium ions were responsible for the impulse (Overton
1902). |
|
|
In 1902, Fischer proposed that proteins consist of chains of
amino acids. [added
02/01/03] |
|
|
In 1902, Ivan Pavlov combined associative learning with reflex
acts, postulating the existence of associated stimuli, or 'conditioned
responses.' Later, he also described two non-associated
behavioral modifications, 'habituation' and 'sensitization.' |
|
|
In 1902, Lucien Claude Cuénot proposed that a gene plus
two enzymes controlled hair color in mice; if both enzymes were
present, it was grey, or if only one, it was black. |
|
|
In 1902, J. W. Gibbs, in Elementary Principles in Statistical
Mechanics Developed With Special Reference to the Rational Foundation
of Thermodynamics, offered a more general approach to statistical
mechanics than Boltzmann or Maxwell. What Boltzmann
had called the Ergoden, Gibbs called the 'grand canonical
ensemble,' and the process of achieving it is known as 'ensemble
averaging.' The principle theme is the "analogy...between
the average behavior of a canonical ensemble of systems and the
behavior of a physical system obeying the laws of thermodynamics"
(Klein 1976:392). This ensemble, or function, has a simple
physical interpretation: the probability of finding at a certaIn time t a point in the small region of phase space around
the point q at momentum p. That Gibbs'
and Boltzmann's books did not become obsolete is due to the
adequacy of classical theory in dealing with the relations between
molecules, whereas quantum theory is necessary to deal with a molecule's
internal structure. |
|
In 1902, Poincaré, in La science et l'hypotheése, noted that it doesn't matter whether or not aether exists, that
'what is essential for us is that everything happens as if it
existed.... [It] is only a convenient hypothsis, [and] some
day, no doubt, the aether will be thrown aside as useless" (Poincaré
1902:211-212). |
|
|
In 1902, Bertrand Arthur William Russell found the 'ultimate
paradox:' If the set of all sets which do not contain themselves
nonetheless contains itself, then it cannot belong to the set of
all sets which do not contain themselves. If it does
not contain itself, then it must belong to the set of all sets which
do not contain themselves. |
|
|
In 1903, the beginning of cytogenetics occurred when, in independent
accounts, Bovari and Walter Stanborough Sutton pointed
out that chromosomes permutated themselves in cell division, halved
their complement in germ cell formation, and paired again in fertilization, in a "physical dance that kept perfect step with Mendel's abstract algebra" (Judson 1979:206). |
|
|
In 1903, Willem Einthoven invented a string galvanometer which
enabled him to produce the first electrocardiogram, or graphic record
of the action of the heart. |
|
|
In 1903, Richard Kraus distinquished natural, or normal, antibodies
from acquired immune antibodies according to their 'avidity,'
or strength. Both Ehrlich and Landsteiner, In contrast, were intent on reducing the difference to one of quantity. |
|
In 1903, Metchnikoff, in Études sur la nature humaine, translated as The Rhythm of Life, argued that death from
old age was only to be feared because of the accompanying pain and
that, as science advanced and old age became less onerous, a natural
wish to die would manifest itself. |
|
|
In 1903, Tsvet made the principle of adsorption the basis of
a new method which would permit the extraction from a solution of
pigments in unchanged forms (Tsvet 1903), and subsequently developed
and named it 'chromatography' (Tsvet 1906). [added
02/01/03] |
|
|
In 1903, Orville Wright and Wilbur Wright achieved flight
in a manned, gasoline power-driven, heavier-than-air flying machine. |
|
|
["The emergence of genetics coincided with the redefinition of the term heredity to refer exclusively to transmission: what had previously
been seen as two aspects of a single subject (transmission and development)
came to be regarded as distinct concerns. By the early decades
of the twentieth century, the study of transmission had become the
province of genetics, whereas that of development--now split off
from genetics--continued as the province of embryology" (Keller
1995:4-5). At the same time as thinking about evolution turned
from Haeckelian comparative anatomy and Weismannian speculation
to the laboratory, embryologists shifted Haeckelian phylogenetic
recapitulation and Weismannian concentration on heredity to a concern
for experiment and developmental mechanics, specifically to His's
immediate causes of morphologies and Roux's Entwicklungsmechnik, or developmental mechanics. Unlike many cytologists, and later
geneticists, who centered their investigations on the chromosomes, embryologists centered theirs on the cytoplasm of the egg.
The geneticists were essentially reductionist; the embryologists
integrative or holistic. Genetic methods looked for differences
through interbreeding; embryological methods, for commonality.] |
|
|
In 1904, Nuttall, using precipitin tests of blood serum proteins, inferred the close phylogenetic relationship between humans and apes. |
|
|
In 1904, T. R. Elliott recognized that chemical agents, and
specifically adrenaline, acted as neurotransmitters in peripheral
nerves, helping the nerve signal across the synapse (Elliott 1904). |
|
|
In 1904 and 1905, Arthur Harden discovered that the presence of phosphate was essential to the enzymes which ferment sugar. |
|
|
In 1904, Lorentz, in "Electromagnetic Phenomena in a System
Moving with Any Velocity Less than that of Light," formulated
the so-called 'Lorentz transformation,' which describes
the increase in mass, the shortening of length, and the time dilation
of a body moving at speeds close to that of light, by which the
space-time coordinates of a moving system can be correlated with
those of any other system. "The quality of not changing under
this or some other transformation is called invarience [which] is
the mathematical expression of symmetry.... Both Maxwell's
electrodynamics and [Albert] Einstein's special relativity
are descriptions which are invariant under Lorentz transformation" (Park 1990:355-356). |
|
|
In 1904, Hantaro Nagaoka proposed a 'Saturn model' of the atom with a nucleus and many electrons in a ring around it. |
|
In 1904 or earlier, Poincaré gave the name the 'principle
of relativity' to the proposition that, since the Universe contained
no standard of absolute rest, anything is moving only in respect to something else. |
|
|
In 1904, Ramsey discovered radon. |
|
|
In 1904, L. P. Teisserenc de Bort published the results of 581 free balloon ascents in which instruments measured the temperatures and pressures in the atmosphere to a height of about 14 km. |
|
|
In 1905, Metchnikoff introduced the theory that white blood cells are able to engulf and kill bacteria (Metchnikoff 1905). |
|
|
In 1905, Nuttall demonstrated the importance of bacteria for digestion. |
|
|
In 1905, John Newport Langley discovered acetycholine, but it was not recognized in the brain until F. McIntosh did so in 1941 (Langley 1905). |
|
|
In 1905, F. Knoop deduced the beta-oxidation of fatty acids. |
|
|
In 1905, Edmund Beecher Wilson, author of Cell Biology In Development and Heredity (published in 1896 and numerous later
editions and others), discovered that the X chromosome is linked to the sex of the bearer. |
|
|
In 1905, Freud, in Drei Abhandlungen zur Sexualtheorie, redrew the line between normality and mental illness: "Not some
mysterious hereditary degeneration read back into infancy, but an
otherwise normal childhood experience that would bear a resemblance
to the adult behavior (or in the case of neurosis, to adult repressed
fantasy)" (Kerr 1993:93). In the same year, in a postscript
to another paper, Freud argued that patients sought to reexperience
old erotic situations by transferring them to their physician. |
|
In 1905, Arrhenius expressed concern about global warming as a result of burning fossil fuels. |
|
In 1905, in the first of three articles in a single issue of Annalen
der Physik, "Übereien die Erzeugung und Verwandlung
des Lichtes betreffenden heuristischen Gesichtspunkt," Einstein sought an explanation of the photoelectric effect, the anomaly
that electrons are emitted from the surface of a metal only if the
incident light is sufficiently short wave length. EinsteIn determined that a massless quanta of light, which he called a 'photon,'
in order to break the attractive forces holding the electrons In the metal, would have to impart the required energy according to Planck's radiation law. "This elegantly quantified
reversion to Newton's corpuscular theory of light by
Einstein was one of the milestones in the the development of quatum mechanics" (Dictionary of Physics 2000:387-3880. |
|
In 1905, in the second article, "Über die von der molekularkinetischen
Theorie der Wärme geforderte Bewegung von in rubenden Flüssigkeiten
suspendierten Teilchen," Einstein studied some consequences
of assuming that liguids and gases are composed of atoms.
Even though too small to see, he conjectured that the presence of
atoms could be confirmed if objects large enough to see were influenced
by their fluctuations. This he demonstrated by showing that
"a particle suspended in a liquid and observed with a microscope
would be seen to dance around under the influence of the random
fluctuations in pressure that are to be expected if the liquid consists
of atoms in rapid motion" (Park 1990:309). This phenomena
was well known to microscope users as Brownian movement. By
inverting Boltzmann's formula, Einstein described its
mathematics, deriving the probability of a macroscopic state for
the distribution of gas molecules, in terms of the entropy associated with that state. |
|
In 1905, in the third article, "Zur Electrodynamik bewegter Körper"
("On the Electrodynamics of Moving Bodies"), Einstein evolved the Special Theory of relativity by working out the consequences
of two postulates: One, the laws of nature are the same for all
frames of reference in uniform, i.e., not accelerating, relative
motion, and, two, light is propagated at a constant velocity which, unlike things in ordinary experience, is independent of the movement
of the emitting body and the observer. In other words, observers
in motion with respect to one another will disagree about length
and time in the other's system. This theory "led to
the discovery that time is associated as a fourth coordinate
on an equal footing with the other three coordinates of space, and
that the scene of material events, the world, is therefore
a four-dimensional, metrical continuum" (Weyl
1918a:201). The Special Theory was invented as "a way--the
only way--to assure the complete validity and self-consistency of Maxwell's equations" (Wheeler and Ford 1998:166).
It also resulted in mathematical equations which confirmed the 'Lorentz transformation' and contained the velocity of a moving body
at the velocity of light relative to an observer, V=(v1+v2)/(1+v1v2/c2)(EinsteIn 1905a:37-65). "The real (and great) merit of the Special Theory...was pedagogical. It arranged the old confusing material in a clear deductive pattern" (Everitt 1976:215). |
|
Later in 1905, in a second paper of the Special Theory of relativity, "Ist die Trägheit einer Körpers von seinem Energiehalt
abhängig?" ("Does the Inertia of a Body Depend upon
Its Energy Content?"), Einstein wrote that "if a
body gives off the energy L in the form of radiation, its
mass diminishes by L/c2.... The mass
of a body is a measure of its energy content" (Einstein, quoted
in Kantha 1996:46). This was published in Annalen der Physik in 1906 and put an end to speculation that the Sun's energy
came from radiation (Einstein 1905b:69-71). |
|
In 1905, Poincaré, in "Sur la dynamique de l'electron,"
obtained, independently of Einstein, many of the results
of the Special Theory of relativity. However, he postulated
nonelectric forces, or 'stresses,' to give stability to
an electron; these were rendered irrelevant by quantum theory. |
|
In 1905 and 1907, Ejnar Hertzsprung published papers relating
colors and brightnesses of stars in a systematic way, and recognizing dwarf and giant stars. |
|
|
In 1906, W. Bateson and Reginald Crundall Punnett reported
less-than-independent assortment, or 'linkage,' in gene alleles on the same chromosome in sweet peas. |
|
|
In 1906, Sherrington showed, in his book The Integrative
Action of the Nervous System, that those cells which send their
fibers and impulses directly to the limb muscles can be influenced to fire by excitation or not to fire by inhibition. |
|
|
In 1906, Frederick Gowland Hopkins noticed that 'accessory food factors,' later called vitamins, were essential to the growth of rats. |
|
In 1906, Andrei Andreyevich Markov described sequences of randomly linked probability variables in which the future variable is determined by the present variable, but is independent of the way in which the present variable arose from its predecessors. These 'Markov chains' launched the theory of stochastic processes. |
|
|
In 1906, Walther Hermann Nernst stated a new tenet, often called
the Third Law of Thermodynamics, according to which if a chemical
change takes place between substances that are at absolute zero
there is no change in entropy. [added 02/01/03] |
|
|
Beginning in 1906, Ferdinand de Saussure lectured on the structural
principles of general linguistics, including the reciprocity of
phonemes and the opposition of diachrony and synchrony (Saussure 1915). |
|
|
In 1907, Ross Granville Harrison cultivated amphibian spinal
cord, demonstrating that axons are extensions of single nerve cells.
In so doing, he invented tissue culture (Harrison 1907). |
|
|
In 1907, Alois Alzheimer characterized the senile degeneration
, to which he loaned his name, by the 'senile plaques' and
'neurofibrillary tangles' which he found in an autopsied brain. |
|
|
In 1907, Arrhenius published Immunochemistry: The Application
of the Principles of Physical Chemistry to the Study of Biological
Antibodies, thereby coining the term 'immunochemistry.' |
|
In 1907, Arrhenius hypothesized that life on earth is descended
from interstellar microorganisms, sucked in by gravity and pushed
out by radiation. This hypothesis is usually called 'panspermia,'
meaning 'life everywhere.' Since, at that time, it was assumed that, even though stars were born and died, the Universe
was in essence eternal and unchanging, the question of its origIn did not have to be addressed (Gribbin and Gribbin 2000:3-4). |
|
In 1907, Einstein, in "Über die vom Relativitätsprinzip
geforderte Trägheit der Energie," deduced the expression
for the equivalence of mass and energy, Ko=mV2, where Ko is energy, m is mass, and V2 is the speed of light squared. ["E=mc2" was the title of a Science Illustrated article which
Einstein wrote in 1954 (Kantha 1996:46).] This relation says
that "a sufficiently energetic packet of radiation (a photon)
can convert into matter with the appropriate mass, and vice-versa" (Gribbin 1998a:172). |
|
|
In 1907, Luitzen Egbertus Jan Brouwer completed his doctoral dissertation on the logical foundations of mathematics which marked the beginning of the Intuitionist School. |
|
|
|
In 1908, Archibald Edward Garrod, in Inborn Errors of Metabolism, recognized that gene products are proteins and showed that certaIn rare, inherited disorders were caused by the absence of specific
enzymes. W. Bateson, in 1902, had suggested to him the probability that an inherited disorder was due to a recessive gene. |
|
|
In 1908, Godfrey Harold Hardy worked out the equilibrium formula
for a population heterogenous for a single pair of alleles: Assuming
the truth of Mendel's laws (and generalizing them), the
resulting combinations will expand into the binomial distribution, or p2(AA) + 2pq(Aa) + q2(aa), where p is the initial frequency of the dominant A in a population and q the initial frequency of the recessive a. This formula was derived independently by Wilhelm Weinberg, and is thus known as the Hardy-Weinberg equilibrium
formula. It provided the first baseline for assessing the effects of mutation. |
|
|
In 1908, William McDougall, in An Introduction to Social
Psychology, postulated that human beings have as many as a dozen
different basic instincts, e.g., curiosity, pugnacity, self-abasement, etc. |
|
|
In 1908, Robert Andrews Millikan determined the probable minimum
unit of an electrical charge, that is, of an electron. Later, he named 'cosmic rays.' |
|
|
In 1908, Planck, attacking Mach's position that physical
theories were based solely on sense data, held that "the physicist
creates the system of the physical world by imposing form
upon it..., creat[ing] the mathematical structures which organize empirical facts" (Janik and Toulmin 1973:138). |
|
In 1908, Hermann Minkowski took Einstein's algebraic
expression of the Special Theory of relativity and geometrized it, coupling space and time into a four-dimensional continuum, and providing
a framework for all later mathematical work in relativity.
"Henceforth, space by itself, and time by itself, are doomed
to fade away into mere shadows, and only a kind of union of the
two will preserve an independent reality" (Minkowski 1908:75). |
|
In 1908, Frank W. Very suggested that the "atmospheres of
the major planets would allow optically visible sunlight to pass
through to the ground, which would heat up and reradiate at infrared
wavelengths. Because the atmospheres are opaque to the infrared
spectrum, this radiation would be trapped beneath the atmosphere
where it could heat up the planetary surface" (Lang and Gingerich 1979:153). |
|
In 1908, Henrietta Swan Leavitt, after years of analyzing the
two Magellanic Clouds, reported finding 1,777 variable stars, and, having derived the periods of a few 'Delta Cepheid-type'
variables, also reported that the brighter among them tended to have longer pulsation cycles. |
|
In 1908, George Ellery Hale completed building the 60-inch reflecting telescope on Mount Wilson in California. |
|
|
In 1908, Zermelo founded axiomatic set theory. |
|
|
In 1909, Charles D. Walcott discovered the Cambrian Burgess Shale fossils. |
|
|
In 1909, Andrija Mohorovicic observed a discontinuity withIn the Earth that marks the junction between the crust and the mantle. |
|
|
In 1909, reports by Correns and Erwin Baur described
the non-Mendelian inheritance of a factor influencing chloroplast
development, thus beginning the recognition of extra-nuclear or cytoplasmic genetics. |
|
|
In 1909, F. Meves proposed that mitochondria originate from preexisting structures of the same kind and carry their own heredity. |
|
|
In 1909, Wilhelm Johannsen published Elemente der exakten
Erblichkeitslehre which was concerned with how to grow pure
lines of beans in view of the fact that natural selection can influence
change only if there is genetic variability. To this end he
distinquished between 'genotype' and 'phenotype,'
the one being variant due to heredity and the other being due to
environment. Naming Mendel's algebraic units 'genes,'
Johannsen understood that to mean that each gene underlies a single trait. |
|
|
In 1909, W. Bateson, in a much expanded new edition of Mendel's
Principles of Heredity, echoed Mivart's idea that
what was selected was born fit. Bateson believed that the
variation giving rise to new species was saltational, but present
from the beginning of life and waiting for disinhibition and expression.
He coined the term 'genetics,' but abjured theorizing: Heredity, the Mendelian variations which he encountered in experiments, failed
to explain big changes. By contrast, Pearson assumed
that selection brought about stable varieties or species based on
the small, incremental differences or gene frequencies in individuals
belonging to groups of vast size. |
|
|
In 1909, Kørbinian Brodmann , in Vergleichende Lokaisationslehre
der Groshirnrinde, published a map of the cortex with 52 areas, each with a function. This map is still in use. |
|
|
In 1909, Edward Tyson Reichert conceived the ambition to plot
the evolutionary relationships among species by the divergences
between their hemoglobin molecules. To this end he published six hundred micrographs of hemoglobin crystals. |
|
In 1909, Charles Jules Henri Nicolle showed that typhoid fever is transmitted by body lice. |
|
|
In 1909, Fritz Haber, in order to synthesize ammonia from its elements, developed the first commercially important high-pressure chemical process. [added 02/01/03] |
|
|
In 1909, Hans Geiger and E. Marsden, under Rutherford's
direction, scattered alpha particles with thin films of heavy metals, providing evidence that atoms possessed a discrete nucleus. |
|
In 1909, Vito Volterra, in "Sulle equazioni integro-differenziali
della teoria dell'elasticit�," writing on the hereditary
phenomena, said that the delayed effects tend to zero when time tends to infinity. |
|
In 1909, Karl Bohlin suggested that the center of the Milky
Way lies within the large collection of globular clusters in the direction of Sagittarius. |
|
In 1909, Vesto M. Slipher showed "photographic emulsions
could record the infrared spectrum and...found that the major planets exhibited infrared absorption lines not present in sunlight.
Subsequently, these bands were identified with amonia and methane" (Lang and Gingerich 1979:67). |
|
|
In about 1909, David Hilbert's work on integral equations
established the basis for his subsequent work on infinite-dimensional space, which came to be called 'Hilbert space.' |
|
|
In 1910, Francis Peyton Rous induced a tumor using a filtered extract of chicken tumor cells. |
|
|
In 1910, Konstantin S. Mereschovsky published an essentially
modern view of the bacterial origin of what later came to be called
eukaryotic cells. |
|
|
In 1910, Thomas Hunt Morgan discovered the white-eye sex linkage
in Drosophila, relating it to Mendel's recessive
traits, and thus initiating fruit fly genetics. His insistence
that genes were not just logical constructs from Mendelian ratios
developed into the general theory of linkage within a chromosome, according to which the strength of the linkage is inversely proportional
to the likelihood that a 'crossover' will occur during
meiosis. Later, he maintained that cytoplasm could be ignored
in studying genetics [Meiosis consists in two divisions of
the diploid nucleus of the fertilized cell accompanied by one division
of its chromosomes. Initially, each chromosome replicates to produce
two sister chromatids as in ordinary division, or mitosis. At this
point the special features of meiosis become evident. Each chromosome
must then somehow pair with its homologue. The pairing allows genetic
recombination, or crossingover, to occur, whereby a random fragment
of a maternal chromatid may be exchanged for a corresponding fragment
of a homologous paternal chromatid (Alberts et al. 1994:1016).
The duplicated homologues separate and "the chromosomes of
each pair pass to opposite poles without separation of their chromatids
[or half-chromosomes]. These chromatids then separate at the second
division. Each of the four nuclei therefore has one of the four
chromatids of each pair of chromosomes" (Darlington 1939:11).
This is a haploid gamete and contains half the number of chromosomes
of the egg. [Meiosis consists in two divisions of the diploid
nucleus of the fertilized cell accompanied by one division of its
chromosomes. Initially, each chromosome replicates to produce two
sister chromatids as in ordinary division, or mitosis. At this point
the special features of meiosis become evident. Each chromosome
must then somehow pair with its homologue. The pairing allows genetic
recombination, or crossingover, to occur, whereby a random fragment
of a maternal chromatid may be exchanged for a corresponding fragment
of a homologous paternal chromatid (Alberts et al. 1994:1016).
The duplicated homologues separate and "the chromosomes of
each pair pass to opposite poles without separation of their chromatids
[or half-chromosomes]. These chromatids then separate at the second
division. Each of the four nuclei therefore has one of the four
chromatids of each pair of chromosomes" (Darlington 1939:11).
This is a haploid gamete and contains half the number of chromosomes
of the egg. [revised
02/01/03] |
|
|
In 1910, P. Boysen-Jensen proved the existence of 'auxins'
which are chemicals instrumental in the the growth of higher plants. |
|
In 1910, Georges Claude discovered that electricity conducted
through a tube of the rare inert gas, neon, gives a bright red glow
and that other gases gave off other colors, e.g., argon gives blue, helium gives yellow and white, etc. Fluorescent light, introduced
in 1935, is a variant containing argon and krypton. |
|
|
In 1910, Alfred North Whitehead and Russell, in Principia
Mathematica, put forth the theory that there is a discontinuity
between a class and its members and attempted to overcome certaIn logical paradoxes by the formal device of branding them meaningless. |
|
|
In 1911, Alfred Henry Sturtevant, an undergraduate student of Morgan's, constructed the first rudimentary map of the
fruit fly chromosome, establishing that genes are real. By
1917, the map was sufficiently continuous to be published. |
|
In 1911, Casimir Funk isolated a crystal, which came to be known
as B-complex, and coined the name 'vitamine.' |
|
|
In 1911, Tsvet, having discovered many forms of xanthophyll
and their chemical relation to carotene, proposed to call the general
group 'carotenoids' (Tsvet 1911). [added
02/01/03] |
|
|
In 1911, Bleuler renamed dementia praecox 'schizophrenia.' |
|
In 1911, Arnold Johannes Wilhelm Sommerfeld hypothesized that
"the interaction between electrons and atoms was definitely
and uniquely controlled by Planck's quantum of action"
(Cao 1997:126-127). |
|
|
In 1911, Rutherford, in "The scattering of a
and b particles by matter and the structure
of the atom," thinking about the nature of the nuclei which
could produce radiation, described the atom as a small, heavy nucleus, surrounded by electrons. |
|
|
In 1911, Charles Thomson Rees Wilson developed the 'cloud
chamber,' a device in which the paths of particles of ionizing
radiation are made visible. The excess moisture in supersaturated
vapor is deposited on the tracks of the ions. |
|
In 1911, Heike Kamerlingh Onmes discovered 'superconductivity,'
the ability of certain materials at low temperatures to carry electric
current without resistance. |
|
In 1911, Einstein, in "Einfluss der Schwerkraft auf die
Ausbreitung des Lichtes" ("The Influence of Gravity upon
the Propagation of Light"), said that if a "light beam is
bent in an accelerating frame of reference, then if the theory is
correct it must also be bent by gravity, and by the exactly equivalent
amount" (Gribben 1998a:90; Einstein 1911:99-108). |
|
In 1911, Hertzsprung published graphs plotting color or spectral
class against the absolute magnitude of stars. In 1913, Henry
Norris Russell, independently, presented similar graphs.
These are now called Hertzsprung-Russell, or HR, diagrams and are
the basis of the theory of stellar evolution. Russell also
suggested that nuclear energy is generated inside stars when they
reach a critical temperature. |
|
In 1911, Jacob Halm argued that the masses of stars are correlated
with spectral type and therefore with their luminosities. |
|
|
In 1912, Alfred Lothar Wegener proposed a unified theory of
continental drift, which opposed to the sinking of continents, based
on fossil and glacial evidence. |
|
|
In 1912, J. F. Gudernatsch, working with frogs, found that removing
the thyroid gland prevents metamorphosis and that feeding thyroid
extracts induces precocious metamorphosis. |
|
|
In 1912, Ernest Everett Just, in "The Relation of the First
Cleavage Plane to the Entrance Point of the Sperm," said that
the former "passes either directly through the entrance-point
of the sperm or a degree or so from it" (Just 1912). [added
02/01/03] |
|
|
In 1912, John Broadus Watson launched his polemic favoring the
objective study of psychology as physicochemically-based behavior
and reputiating introspection as unscientific. He denied the
value of studying either consciousness or instinct, suggesting one
could never be certain that a given behavior is free of learning. |
|
|
In 1912, Jung conceptualized and named 'introvert' and
'extrovert,' and suggested the study of current conflicts
for insights into the triggering of repressed, infantile contents. |
|
|
In 1912, Max Theodor Felix von Laue obtained the first diffraction
effects by letting X-rays fall on a crystal. Almost immediately, William Lawrence Bragg proposed a simple relationship between
an X-ray diffraction pattern, or characteristic interference pattern, and the arrangement of atoms in a crystal that produced the pattern, thereby inventing X-ray crystallography. |
|
|
In 1912, Louis Carl Heinrich Paschen and Ernest E. A. Back discovered that atomic line spectra have a splitting pattern In a very strong magnetic field. |
|
In 1912, Victor Hess, in the course of a balloon flight, noted
increasing radiation above 5000 feet and proposed an extra-terrestial
source. |
|
In 1912, Slipher obtained spectrograms of the Andromeda Nebulae, M31, which all showed clear evidence of a Doppler blueshift. By 1914, he had measured a dozen more Doppler shifts, all but one toward red. |
|
In 1912, Leavitt concluded that those Cepheid-types In the smaller of the two Magellanic Clouds are so far away that they
may be regarded as being roughly at the same distance and was thus
able to work out the relationship between their luminosity, or energy
output, and orbital period. |
|
|
In 1913, Lawrence Joseph Henderson proposed that the concept
of fitness, which in animals is the relative ability to transmit
its genes to the next generation, be extended to the environment.
This has ramifications for the origin of life. |
|
|
In 1913, Shiro Tashiro discerned slight increases in carbon
dioxide production by stimulated nerves. |
|
|
In 1913, C. Fabry and M. Buisson reported the existence
of ozone, a gas created by a photochemical reaction between sunlight
and oxygen. |
|
|
In 1913, Henry Gwyn-Jeffreys Moseley bombarded the atoms of
various elements with X-rays and found that the wavelength decreased
in proportion to the increase in the atomic weight of the element
emitting the rays. From observing the wavelength, he discovered
that the inner stucture responded in a characteristic group of lines, enabling the assignment of 'atomic numbers.' The periodic
table turned out to coincide with these numbers rather than, as
had been supposed, the atomic weight. |
|
|
In 1913, Niels Bohr,in "On the constitution of atoms and
molecules," strongly influenced by Sommerfeld, applying
the Planck quantum hypothesis to Rutherford's
atomic model and postulating stable states and single frequencies, calculated closely the frequencies of the spectrum of atomic hydrogen
(which has a single electron). "Only certain photon energies
are ever seen, identified by their corresponding frequencies or
wavelengths, and this explains the appearance of the spectrum"
(Park 1990:312). This supported his proposal that electrons
moved around the nucleus in restricted orbits and his explanation
of the manner in which the atom absorbs and emits energy by leaping
from one orbital to another without traversing the space in between, and was the first theory of quantum mechanics. |
|
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In 1913, Frederick Soddy discovered that different forms of
the same element were, in fact, groups of elements with the same
chemical character, but varying in their masses, and that radioactive
decay is accompanied by the transmutation of one element to another.
To express this new found complexity of matter, the term isotopic
element, or isotope, was used. |
|
In 1913, Einstein and Marcel Grossman, in "Entwurf
einer verallgemeinerten Relativitätstheorie und eine Theorie
der Gravitation," investigated curved space and curved time
as it related to a theory of gravity. Einstein contributed
the physics and Grossman the mathematics. |
|
In 1913, Hertzsprung, using statistical parallax, got an indication
of the distance to a couple of Cepheids and was able to extrapolate
a rough measure in numbers of the distance to the Small Magellanic
Cloud, which was much farther away than had been imagined. |
|
In 1913, Cartan, in "Les groupes projectifs qui ne kaissent
invariante aucune multiplicité plane," announced his discovery
of linear two-dimensional representations of the three-dimensional
orthogonal matrix known as "a spinor..., a sort of 'directed'
or 'polarized' isotropic vector; a rotation about an axis
through which an angle 2p changes the
polarization of this isotropic vector" (Cartan 1937:41).
'Spin' is quanticized rotation and always comes in multiples
of a basic unit which is equal to one-half times Planck's
contant h divided by 2p.
Cartan's concept was used by Einstein in the mathematics
of the theory of General Relativity. |
|
In 1913, Leo Baekeland invented a plastic laminate, known as
Bakelite, and later as formica. |
|
|
In 1914, Nicholas Vaschide published his hypothesis that sleep
is not just the absence of being awake, but is a vital instinctual, i.e., biological, process. |
|
In 1914, James Franck and Gustav Hertz confirmed experimentally Bohr's theory of the stationary states of the energy
levels in atoms by producing "jumps between them, supplying
the excitation energy by collisions with accelerated electrons"
(Segrè 1976:137). |
|
|
In 1914, Arthur Stanley Eddington hypothesized that spiral nebula
were actually distant galaxies. |
|
In 1914, Harlow Shapley established that the Cepheid variables
are pulsating stars, not binaries. |
|
|
In 1915, Jacques Loeb, in The Organism as a Whole, maintained
that a complicated organism was unimaginable without a prestructure
in the egg which he characterized in colloidal chemistry terms.
He also maintained that behavior consisted in stereotypic movements, directly elicited and controlled by sensory stimuli. |
|
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In 1915, Morgan, Sturtevant, Calvin Blackman Bridges, and Hermann Joseph Muller published The Mechanism of Mendelian
Inheritance. |
|
|
In 1915, Bridges discovered the first homeotic mutation in Drosophila, 'bithorax.' |
|
|
In 1915, Haber, directing Germany's chemical warfare activities, initiated the use of poison gas releasing 150 tons of compressed
chlorine on Allied positions around Ypres. Nernst also was
a leader in the Germany's chemical warfare effort. In 1917, James Bryant Conant was put in charge of the United States'
Chemical Warfare Service which was attempting to develop mustard
gas (L. F. Haber 1986). [added
02/01/03] |
|
In 1915, in three lectures delivered to the Prussian Academy, and published
the following year as Grundlage der allgemeinen Relativitätatheorie (Foundation of General Relativity), Einstein completed
the mathematical generalization of the theory of relativity: Whereas
spacetime in the Special Theory is geometrically flat, in the General
Theory spacetime is curved and includes gravity as a determinant, i.e., "a ray will experience a curvature of its path when passing
through a gravitational field, this curvature being similar to that
experienced by the path of a body which is projected through a gravitational
field" (Einstein 1916:127). Or, in other words, under
the force of gravity, objects follow "a path of least resistance, the equivalent of a straight line, through a curved portion of space, or spacetime" (Gribbin 1998a:90-91). This is the first
example of concepts from differential geometry being used to represent
physical structures; thus, in order to get from a flat to a curved
spacetime manifold, "one replaces in all tensorial (or spinorial)
relations the flat metric h by the curved
one, g, and one substitutes covariant derivatives with respect
to the latter for those with respect to the former" (Ehlers
1981:536). In fact, in one these lectures, Einstein attributes
"dem Zauber dieser Theorie," i.e., the magic of the theory, to the differential calculus methods of "Gauss, Riemann, Christoffels, Ricci und Levi-Civita" (Einstein, quoted in Ibid.:536). |
|
Einstein's
1915 theory replaced the Kepler-Newton theory of planetary
motion, which was based on the assumption of absolute space, with
one which is able to account for the slow rotation, in the direction
of motion, which the orbital ellipse of a planet undergoes.
Einstein's value for the bending of light waves by the Sun is
"almost precisely the same value" as von Soldner's
for light particles, which is to say that it is not space-bending
but time-bending which differs from Newtonian calculations (GribbIn 1998a:53). Employing Riemann's non-Euclidean geometry
and equations which are highly non-linear, Einstein was able to
predict radically new phenomena: The bending of light around the
Sun and the precession of the perihelion of Mercury. |
|
|
In 1916, Gilbert Newton Lewis said that the chemical bond consists
of two electrons held jointly by two atoms. |
|
|
In 1916, Karl Schwarzschild , in a paper which Einstein delivered
to the Prussian Academy and which was based on the General Theory
of Relativity, calculated that a star collapsing under its own gravitational
force would cease to radiate energy beyond a certain parameter.
This parameter is known as the 'Schwarzschild radius' and
shrinking beyond it creates a 'black-hole.' Since
inside a black-hole, according to Schwarzschild's solution, the curvature becomes infinite, and since this is a 'singularity,'
i.e., not generally believable to physicists, it was not taken seriously
for many years. In fact, when it was taken seriously, it
was realized that there were two opposite solutions and that
the singularity was an artefact of the coordinate system chosen
by Schwarzschild to measure spacetime around a black-hole.
The second solution is the origin of the notion of the existence
of 'white-holes' and describes the expansion out of an initial
singularity. Black-holes were not actually called that until, in 1968, John Archibald Wheeler used that name for what had
been previously a 'Schwarzschild singularity,' a 'collapsed
star,' or a 'frozen star' (Wheeler 1968:9). |
|
In 1916, Eddington, in "On the Radiative Equilibrium of
Stars," said that the pressure of radiation takes its place
beside gas pressure and gravity as an equilibrating force. |
|
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In 1916, Sommerfeld modified Bohr's atomic model
by specifying elliptical orbits for the electrons. |
|
|
In 1916, Irving Langmuir concluded that adsorption, the condensation
of gas on a surface, is a single molecular layer thick and chemically
bonded to the surface. It is not, as most thought, analogous
to the physical attraction which holds the earth's atmosphere.
He also noted that the length of hydrocarbon chains makes no difference
to the shape of the surface energy curve provided that there are
more than 14 carbons in the molecule (Langmuir 1917). |
|
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In 1917, J. Schmidt demonstrated that the differences between
individuals in a population were genetic. Richard Benedict Goldschmidt, in 1920, and Francis Bertody Sumner, in 1924, demonstrated it in other populations. Their findings
caused the downfall of the mutationalist and Lamarckian theories
of de Vries and Bateson and "permitted a selectionist
interpretation of slight differences among local populations that
were obviously caused by differences in the environment" (Mayr 1959:4). |
|
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In 1917, D'Arcy Thompson, in Growth and Form, took
basic body plans and changed the size and position of the parts
relative to one another in geometric ways, showing how evolution
might have proceeded. His thesis was that form "is determined
by its rate of growth in various directions, hence rate of growth
deserves to be studied as a necessary preliminary to the theoretical
study of form" (Thompson 1917:51). |
|
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In 1917, Landsteiner and H. Lampl found that antibodies
could be produced which reacted with synthetic haptens, that is
to say, with incomplete antigens which are unable to induce antibody
formation. This finding seemed for a long time to support
a template model of antibody formation (Landsteiner and Lampl 1917). |
|
In 1917, William D. Harkins noticed that terrestial elements
"of low atomic weight are more abundant than those of high atomic
weight and that, on average, the elements with even atomic numbers
are about 10 times more abundant than those with odd atomic numbers
of similar value, [and conjectured] that the relative abundances
of the elements depend on nuclear rather than chemical properties
and that heavy elements must have been synthesized from light ones"
(Lang and Gingerich 1979:374). |
|
In 1917, Einstein, in "Kosmologische Betrachtungen zur allgemeinen
Relativitätstheorie" ("Cosmological Considerations
on the General Theory of Relativity"), by adding a 'cosmical
constant,' was able to describe a universe that conformed to
what he and everyone else supposed: A closed and static sphere coextensive
with the Milky Way (Einstein 1917:177-188). The same year, Willem de Sitter offered a different solution to the General
Relativity equations, one which contained "negligibly small
values for the mass density and pressure in ordinary matter"
and thus permitted "exponential expansion" (Peebles 1993:77,393).
In fact, these equations, without the addition of a cosmical contant
and including matter, were solvable provided that the universe was
not static but rather expanding or contracting. Moreover, mathematicians soon predicted a redshift as test-particles moved
away from each other. |
|
In 1917, Heber D. Curtis pointed out that the nova he observed
in spiral nebulae were 100 times farther away than nova in the the
Milky Way. This supported the island universe theory of spiral
nebulae. |
|
In 1917, Slipher, using spectral analysis of spiral nebulae, recognized that they were generally receding from us at a high velocity. |
|
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In 1917, James Hopwood Jeans submitted an essay in which he
described a general theory of the configuration of equilibrium of
compressible and non-homogeneous masses of astronomical matter, enabling him to explain the behavior of certain nebulae and describe
the evolution of gaseous stars. |
|
In 1917, Levi-Civita recognized "the geometrical meaning
of the Christoffel symbols as determining a natural parallel
transport of vectors and tensors on Riemannian manifolds [which
was important] in the subsequent development of differential geometry
and field physics" (Ehlers 1981:527). |
|
|
In 1918, Ronald Aylmer Fisher wrote the initial paper, "The
correlation of relatives under the supposition of Mendelian inheritance,"
of what came to be known as population genetics, the joining of
Mendelian experiments with a statistical approach to large populations. |
|
|
As
early as 1918, Paul Portier became convinced that mitochondria were direct descendents of bacteria. |
|
|
In 1918, Bridges, working with Drosophila, suggested that gene duplications promote the evolution of organisms toward greater complexity. |
|
In 1918, J. S. Szymanski demonstrated that animals are capable of maintaining approximately 24-hour activity patterns without external or temperature clues. |
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In 1918, Amelie Emmy Noether, in "Invarianten beliebiger Differentialausdrücke" and "Invariante Variationsprobleme,"
demonstrated the theorem that "wherever there is symmetry In nature, there is also a conservation law, and vice-versa. In other words, the symmetries of space and time are not only linked
with conservation of energy, momentum, and angular momentum, but each implies the other" (Crease and Mann 1986:189). |
|
|
In 1918, Hermann Klaus Hugo Weyl, in "Gravitation und Elektricitat"
and two other papers, produced the first unified field theory In which the electromagnetic and gravitational fields appeared as a
property of space-time (Weyl 1918a:201-216). To do so, he found it necessary to describe random changes in another aspect
of a system as being precisely compensated by changes in another aspect. This he called 'measuring rod symmetry,' and later 'gauge invariance' (Weyl 1918b:176; 1928:100).
A gauge transformation is simply a relabelling exercise, e.g., when the Earth rotates, the distance between New York and London remains
the same. According to Weyl, "a state of equilibrium is likely to be symmetric.... The feature that needs explanation
is, therefore, not the symmetry of [a] shape but deviations from this symmetry" (Weyl 1952:25-26). |
|
In 1918, Shapley, using the Mount Wilson observatory, Leavitt's
period-luminosity law, and employing a statistical method of his own devising--i.e., he assumed the brightest stars in globular clusters
had all the same intrinsic brightness, was able to show the dimensions of the Milky Way galaxy and the Earth's peripheral place In it. |
|
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In 1918, Ludwig Wittgenstein, in Tractatus Logico-Philosophicus, pointed out that "what can be said at all can be said clearly; and
whereof one cannot speak thereof one must be silent" and "the sense of the world must lie outside the world" (Wittgenstein 1918:27,183). |
|
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In 1919, Harry Steenbock demonstrated the relationship between the plant pigment 'carotene' and vitamin A. |
|
|
In 1919, Ernst Spath produced a synthetic version of peyote's psychoactive alkaloid, which he called 'mescaline.' |
|
|
In 1919, Pierre Janet pointed out that the hypnotic condition must be learned by the subject: If the subject has never heard of hypnotism, it is unlikely that he can be hypnotized. |
|
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In 1919, E. Rutherford discovered the proton, which contains the positive charge within the nucleus of an atom, and published
the first evidence of artificially-produced splitting of atomic nuclei; that is, he produced hydrogen through the bombardment of
nitrogen with alpha radiation. His discovery made possible the description of the electrostatic force; namely, if each of two bodies have an
excess of electrons or an excess of protons, repulsion occurs, but if the two bodies differ in their excesses, then attaction occurs. |
|
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In 1919, Francis William Aston designed the mass spectograph and discovered neon isotopes with it, enabling him to explain nonintegral atomic weights. This revealed that the helium atom was less massive than four hydrogen atoms, pointing to the transmutation of the first two elements. "Of the nearly 300 isotopes of elements, Aston isolated and measured the masses of more than 200" (Hoyle 1994:149). |
|
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In 1919, Eddington and Frank W. Dyson measured the bending of starlight by the gravitational pull of the sun, thus confirming Einstein's general theory of relativity. |
|
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In 1920, Hermann Staudinger began to work on macromolecules, such as proteins, which had hitherto been thought by many to be
aggragates. Others questioned the strength of the atomic forces. |
|
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In 1920, Otto Loewi showed that the terminal branches of nerve fibers release stimulating and inhibiting chemicals. |
|
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In 1920, Friedrich A. von Hayak, in The Sensory Order, postulated that all perception is a product of memory and
an act of classification of the qualities of objects and events
performed by maps of cortical cells. These interconnections
are reinforced by the experience of prior contact. This essay
was not published until 1952. |
|
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In 1920, Jung, in Psychologische Typen, first used the
term 'anima,' a word borrowed from Plato, who used
it to represent the soul of the individual. Jung used it to
represent the archtype of the mediator between consciousness and
the collective unconscious (for men; for women, he used 'animus').
Ignoring these mediators meant the failure to acknowledge all parts
of a cognitive whole with the consequence that the hidden part would
be dominant. |
|
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In 1920, E. Rutherford postulated the existence of the neutron, required in order to keep the positively-charged protons in the
nucleus from repelling each other. Their existence explains
why some atoms have identical chemical properties to one another
but slightly different mass. |
|
In 1920, Eddington, in "The Internal Constitution of the
Stars," spelled out the implications of Aston's discovery, namely: "Mass cannot be annihilated, and the deficit can only
represent the mass of the electrical energy set free in the transmutation.
We can therefore at once calculate the quantity of energy liberated
when helium is made out of hydrogen. If 5 percent of a star's
mass consists initially of hydrogen atoms, which are gradually being
combined to form more complex elements, the total heat liberated
will more than suffice for our demands, and we need look no further
for the source of a star's energy" (Eddington 1920:19). |
|
In 1920, Meghnad Saha, in "Ionization of the Solar Chromosphere,"
obtained an equation relating the degree of ionization of an atom, analogous to the dissociation of a molecule, to temperature and
pressure, and thus accounting for the relative intensities of different
spectral lines. |
|
In 1920, Michelson and Francis G. Pease, using an optical
interferometer, measured the first stellar diameters, Betelgeuse and five other supergiant stars. |
|
|
In the early 1920s, it was ascertained that there were two sorts of
nucleic acid, deoxyribonucleic acid and ribonucleic acid. |
|
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In the early 1920s, Victor Jollos hypothesized that the disappearance
of environmentally-induced acquired traits even after hundreds of
generations indicated that their acquisition should be assigned
to the cytoplasm rather than the nucleus. |
|
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In 1921, Frederick Grant Banting and Charles Herbert Best isolated insulin while working on pancreatic secretions. Banting
injected it into an apparently terminally ill patient who survived. [revised
02/01/03] |
|
|
In 1921, Felix d'Hérelle discovered bacterial viruses
which he named 'bacteriophage' (d'Herelle 1926). |
|
In 1921, Muller raised the question of the relationship of genes
to viruses, or 'naked genes' (Muller 1922). [revised
02/01/03] |
|
|
In 1921, Langley described the autonomic nervous system and
its functions. |
|
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In 1921, Hopkins isolated gluthione. |
|
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In 1921, Theodor Kaluza , in "Zum Unitätsproblem der
Physik," wrote down Einstein's field equations In five dimensions. This reproduced the usual four-dimensional
gravitational equations plus Maxwell's equations for
the electromagnetic field. In other words, according to this
hypothesis, electromagnetism is not a separate force, but an aspect
of gravity in a higher dimension. |
|
In 1921, Otto Stern and Walter Gerlach demonstrated 'space
quantization' "by sending a molecular beam, a tenuous
stream of molecules or atoms, through a suitable magnetic field
and observing their deflection.... The atoms orient themselves
only in discontinuous positions" (Segrè 1976:138). |
|
|
In 1922, Herbert Spencer Gasser and Joseph Erlanger, working together, and Edgar Douglas Adrian found that the
electric pulses within neurons caused chemicals to be released and
that their rate of conduction was proportional to the thickness
of their sheaths. |
|
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In 1922, Walter Garstang , in "The Theory of Recapitulation:
A Critical Re-statement of the Biogenetic Law," showed that
phylogeny is not the cause but the product of different ontogenies
(Garstang 1922). |
|
|
In 1922, Elmer Verner McCollum led a team which showed that
rickets is caused by a lack of a new food factor, vitamin D. |
|
In 1922, Arthur Holly Compton demonstrated an increase in the
wavelengths of X-rays and gamma rays when they collide with loosely
bound electrons. This verified the quantum theory since the
effect requires the rays be treated as particles, not waves (Compton
1923:483-502). |
|
In 1922, Arthur Holly Compton demonstrated an increase in the
wavelengths of X-rays and gamma rays when they collide with loosely
bound electrons. This verified the quantum theory since the
effect requires the rays be treated as particles, not waves (Compton
1923:483-502). |
|
|
In 1922, and 1924, Aleksandr Friedman, in "Über die
Krümmung des Raumes," proposed several nonstatic, realistic
models of an expanding (or contracting) decelerating universe which
were consistent with Einstein's General Theory of Relativity.
These models assumed that the universe was of uniform curvature
and uniform matter (idealized as dust exerting neglible pressure), that the expansion was not caused by galaxies moving apart, but
by space itself stretching, and predicted that the beginning and
the end of time would occur for dynamical reasons. |
|
In 1922, Edwin Powell Hubble demonstrated the nebulae which
failed to generate their own light were gaseous and located withIn the Milky Way galaxy. |
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|
|
In 1923, Oswald Avery demonstrated that different types of pneumococci
had different and specific exterior capsules and that bacteria are
of distinct, heritable varieties. |
|
|
In 1923, Bridges discovered chromosomal translocation in Drosophila. |
|
|
In 1923, Otto Heinrich Warburg reached the conclusion that "cancer
cells differ from non-cancer cells, including growing embryonic
cells, by their failure to suppress glycolysis in the presence of
oxygen" (Krebs 1981:20). Today, it is realized that this only
one of many ways cancer cells differ; it is a symptom and
not the primary cause. |
|
|
In 1923, Robert Feulgen discovered a selective staining technique
for DNA localization, which is still in use. |
|
|
In 1923, Lloyd Morgan, in his book Emergent Evolution, used the word 'emergent' to show that higher orders are
not mere resultants of what went before, but were qualitatively
new. |
|
|
In 1923, Thorsten Ludvig Thunberg characterized photosynthesis
as an oxidation-reduction reaction in which carbon dioxide is reduced
and water is oxidized. |
|
|
In 1923, Johannes Nicolaus Brönsted published his theory
of the acid-base phenomena according to which any group of atoms
that gives up a proton is called an acid, etc. In the same
year, G. N. Lewis published his theory that neutralization
accounts for the coordinate covalent bond between the acid and the
base. His theory incorporated Brönsted's proton theory
as a special case. |
|
In 1923, Herbert M. Evans and K. Scott Bishop discovered
vitamin E (Evans and Bishop 1923). |
|
|
In 1923, Jean Piaget, in Le Langage et la pensée chez
l'enfant, maintained that child development proceeds In the same sequence of genetically determined stages. |
|
|
In 1923, Eddington published The Mathematical Theory of Relativity, considered by Einstein the finest presentation of the subject
in any language. |
|
In 1923, Werner Heisenberg and Max Born, using Bohr's
quantum mechanics, were finally able to calculate the wavelength
of the two electron helium atom. |
|
In 1923, Louis Victor de Broglie (rimes with feuille), in "Ondes et quanta," hypothesized that a moving electron
particle has wave-like properties. "His central contribution
was formula giving the relation between the momentum p of
a particle and the wavelength l of its associated wave, analogous to the earlier relation between
energy and frequency, l= h/p = h/mv, where for p is substituted the usual expression for the momentum
of a moving object.... Assume a circular path, and assume
that the wave makes a pattern that is closed on itself....
The circumference of the circle is a whole number of wavelengths:
2pr = nl, where n = 1,2,3,.... By de Broglie's hypothesis, this 2pr = nh/mv, whence mvr
= nh/2p, and this, as if by miracle, is the formula Bohr had had to guess in 1913 in order to
derive his formula for the energy levels of hydrogen" (Park
1990:316). |
|
In 1923, Electrolux produced the first electric refrigerator. |
|
|
In 1923, Vladimir Zworykin invented the iconoscope television
camera-tube. |
|
|
In 1924, Aleksander Ivanovitch Oparin published his speculation
that life, that is to say, metabolism + self-reproductivity (but
not replication) + mutability, is preceded by the formation of mixed
colloidal units, called coacervates, and is the inevitable result
of chemical self-organization in a reducing environment (OparIn 1924). A reducing atmosphere is rich in hydrogen and hydrogen-containing
gases, such as methane and ammonia, all of which "donate electrons
to other substances and thereby produce energized molecules.
These molecules are then able to take part in chemical reactions
that can lead to the creation of more complex substances" (Darling
2001:17). |
|
|
In 1924, E. Gorter and F. Grendel demonstrated that blood
cells are surrounded be a membrane exactly two molecules thick (Gorter
and Grendel 1925:439). [added 02/01/03] |
|
In 1924, John Burdon Sanderson Haldane began a series of papers
in which gene frequency substitutions in a population were treated
systematically. |
|
|
In 1924, Alfred Lotka, in Elements of Physical Biology, compared the global eco-system to "a great world engine" in which
"plants and animals act as coupled transformers of energy" in "the
mill-wheel" that is driven by "solar energy" (Lotka 1924:331-335).
Lotka gave analytical substance to the vision intuitively
adopted by field biologists. Population ecologists took the
'logistical equation' for population growth, which is In fact based on an analogy with autocatalytic chemical reactions, from his book. |
|
|
In 1924, Satyendranath Bose derived Planck's black
box radiation law from photon statistics, that is, independent of
classical electrodynamics. Instead of photons being statistically
independent, he assigned them to cells and wrote of the cell's
statistical independence. |
|
In 1924, Bohr, Hendric Anton Kramers, and John C. Slater tried and failed to solve the apparent contradiction between
waves and particles by the concept of the 'probability wave.'
This probability is different from chance: "It meant a tendency
for something. It was a version of the old concept of potentia in Aristotelian philosophy. It introduced...a strange
kind of physical reality just in the middle between possibility
and reality" (Heisenberg 1958:41; Bohr et al. 1924:785-812). |
|
In 1924, Bose, in "Wärmegleichgewicht im Strahlungenfeld
bei Anwesenheit von Materie," and Einstein, in an appendix
to Bose's paper, predicted the existence of the statistical
phenomena, now known as 'Bose-Einstein condensation,' whereby
a significant fraction of particles at a sufficiently low temperature
could occupy the same quantum state of lowest energy. In other words, in this state, the atoms--later recognized as particles of integer
spin and still later called 'bosons,' in Bose's honor--would
lose their individual properties and would act collectively as a
single entity. Integer spin is either zero or an even number
of multiples of the basic unit of spin. |
|
|
In 1924, Eddington, in "On the Relation between the Masses
and Luminosities of the Stars," correctly derived the various
mass-luminosity relations of stars; e.g., for stars like the Sun, the absolute luminosity is proportional to the fourth power of the
mass, but for more massive stars the absolute luminosity is proportional
to the cube of the mass. |
|
In 1924, Carl Wirtz suggested that the smaller a galaxy appeared
the larger its change in color toward the red end of the spectrum.
This is called 'cosmological redshift.' But Wirtz
lacked the direct evidence to conclude that these smaller, redder
galaxies were farther away. |
|
In 1924, Hubble, using the 100-inch telescope on Mount Wilson
and the same scale which Shapley had used to map the Milky
Way, measured the distance to the nearer spiral galaxies, which
was two million light years. So vast was this distance that
"the whole Galaxy in which we live was suddenly shrunken, In the astronomical imagination, into a tiny mote floating in a vast, dark sea of emptiness" (Gribbin 1998a:65). |
|
|
In 1925, Raymond Arthur Dart published his discovery of a skull
of a new species, Australopithecus africanus, a missing link
in the human fossil record. He speculated that "Australopithecus had been a bloodthirsty carnivore, [giving birth to] the killer
ape myth..., including a connection between warfare and hunting
and the concept that aggressiveness drives cultural progress"
(de Waal 2001:45). |
|
|
In 1925, Gilbert Adair published his determination of the correct
size of the hemoglobin molecule and subsequently wrote the equation
for hemoglobin's cooperativity. |
|
|
In 1925, George Richard Minot and William Parry Murphy noticed that feeding raw liver aids in the treatment of 'pernicious
anemia.' Their discovery led to the isolation of vitamIn B12. |
|
|
In 1925, Theodor Svedberg designed the ultracentrifuge. |
|
|
In 1925, Samuel A. Goudsmit and George Eugene Uhlenbeck assigned angular momentum to electrons and established that they
have the quantum mechanical property of spin. |
|
In 1925, Heisenberg, in "Über quantentheoretische Umdeutung
kinematischer und mechanischer Beziehungen," in order to avoid
giving definite numbers to changing positions of quanta, changed
the relationship between physical concepts and mathematical symbols
through his use of symbols as imaginary quantities with arrays of
numbers, called matrices. The rules for calculating these
symbols often depends on the order they are written down.
This became known as 'matrix mechanics.' |
|
|
In 1925, Wolfgang Pauli perceived the principle that no two
electrons in the atom can be in the same quantum state; in other
words, two electrons must have opposite spin, thus cancelling each
other, and there can be no more than two in the same orbital. This
is known as the 'Pauli exclusion principle.' |
|
In 1925, Enrico Fermi devised a statistical mechanics valid
for particles subject to the exclusion principle, i.e., particles
of half-integral spin, e.g., electrons, protons, neutrons, etc.
Such particles came to be called 'fermions' in his honor.
As Paul Adrien Maurice Dirac, independently, made the same
calculation, these equations are now known as Fermi-Dirac statistics. |
|
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In 1925, Ernst Ising published a one-dimensional model of ferromagnetism
in an attempt to explore the problem of atoms in a solid, each with
a magnetic moment and a spin. This model demonstrated that
the energy of the system is taken to be proportional to the amount
of magnetism and that at any temperature above absolute zero there
would be no spontaneous magnetism. One- and two-dimensional
models have applications for phase transitions and interfaces In semiconductor technology. |
|
In 1925, Gustaf Ising published a proposal for a 'linear
accelerator.' |
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In 1925, Pierre Auger discovered that the ejection of an electron
without the emission of a X- or gamma-ray photon is the result of
the de-excitation of an excited electron within the atom. |
|
In 1925, Walter Noddack and Ida Eva Tacke, who married Noddack the following year, discovered the element rhenium. |
|
In 1925, Cecilia H. Payne, in Stellar Atmospheres, "assumed
that the number of effective atoms required to make a spectral line
barely visible in a stellar spectrum is the same for all lines of
all elements and that the reciprocals of those fractional concentrations
could be used to give the relative abundances of the elements.
The results showed that the relative abundances [except for hydrogen]
are similar to those in the Earth's crust" (Land and Gingerich
1979:244). |
|
In 1925, Bertil Lindblad said that star streaming is evidence
that the entire Galaxy is differentially rotating. |
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In 1925, George Y. Rainich, while re-expressing the content
of the Maxwell-Einstein equations in a purely geometric form, established that, "under certain assumptions, the electromagnetic
field is entirely determined by the curvature of space-time"
(Rainich 1925:107). |
