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- [641] HERMITE
- [642] PASTEUR
416 [636] GALTON
THOMSON [637] applying statistical methods to biology. He was also the first to study identical twins, where hereditary influences might be considered identical so that dif ferences could be attributed to envi ronment only. He also demonstrated the permanence and individuality of finger prints. These had been studied as early as 1823 by Purkinje [452], but it was Galton who began to work out a thoroughgoing system of fingerprint identification. By the end of his lifetime, spectacular solutions of crime cases through fingerprints had established their use both in Great Britain and the United States. In 1869 he showed that mental abili ties varied among mankind along a bell shaped curve as Quetelet [496] had shown was true of physical charac teristics. By studying the occurrence of high mental ability in families he was able to present evidence in favor of the view that mental ability was inherited and took up a strong position in favor of heredity in the perennial heredity-versus- environment dispute. However, he had a tendency to go fur ther than the state of the art really per mitted. He felt that mental 'ability could be measured accurately by the tech niques of the time. (His faith in mea surement went beyond the reasonable. He tried to map the distribution of good looks in England and to test the efficacy of prayer by statistical methods.) He also felt that the incidence of desirable characteristics in humans could be in creased by proper breeding and in 1883 he gave the name eugenics to the study of methods whereby this could be brought about. He was knighted in 1909, and when he died shortly thereafter, working to the end, he left a bequest for the estab lishment of a laboratory devoted to re search in eugenics. Unfortunately, the mode of inheri tance of various human abilities are even now not well understood, and it seems quite certain that the complexities are such that we have no idea of how to breed in one ability without, perhaps, breeding out some others of equal value. Furthermore, with Mendel’s discovery of recessive characteristics and with modern understanding of the incidence of spon taneous mutation, it is further under stood that undesirable characteristics can only be bred out of the species after an excessively long period and even then with no guarantee against recurrence. Nevertheless, the ends of eugenics are so desirable that it cannot be given up entirely and, in later times, men such as H. J. Muller [1145], while recognizing the difficulties, nevertheless presented reasoned programs that would in their opinion achieve some beneficial results. Unfortunately, the loudest contemporary advocates of eugenics are nonscientists who use the language of science to beat their private tom-toms of racism. [637] THOMSON, Robert William Scottish engineer Born: Stonehaven, Kincardine, 1822
Died: Edinburgh, March 8, 1873 Thomson was sent to Charleston, South Carolina, as a youth to gain expe rience as a merchant. He was more in terested in engineering, however, and when he returned to Great Britain, he began a program of self-education in which he was encouraged by Faraday [474], the greatest of all the self educated scientists. For a time Thomson worked with Stephenson [431] on rail ways.
Thomson’s most important invention, in 1845, was the use of a rubber strip in tended to fit around wheels; that is, the rubber tire. He intended it for use in car riages to muffle shocks and vibration, but it soon came to be used for bicycles. In deed, it is difficult to see how bicycles could have become as practical and pop ular as they did become in the latter part of the nineteenth century without Thom son’s rubber tire. And, of course, the notion came truly into its own well after the inventor’s death, when it began to be used on the wheels of automobiles, buses, trucks, and even airplanes. 417 [638] MENDEL
MENDEL [638] [638] MENDEL, Gregor Johann Austrian botanist
Hyncice, Czechoslovakia), July 22, 1822
Brno, Czechoslovakia), January 6, 1884 Mendel entered the Augustinian order, after a childhood of poverty and hard ship, during which, as the son of a peas ant, he tended fruit trees for the lord of the manor. He obtained an education with difficulty while trying to support himself by tutoring. Finally, in 1843 he entered an Augus tinian monastery. He assumed the name Gregor on becoming a monk, and was ordained a priest in 1847. He lived at the Abbey of St. Thomas in Brünn. Since the Augustinians supplied teachers for the Austrian schools, Mendel was sent to the University of Vienna in 1851 for training in mathematics and science. He attended lectures by Doppler [534], for instance. In 1854 he became a sci ence teacher at the Brünn Realschule, after having failed three times to pass examinations (experiencing a nervous breakdown in the process). As a result, he did not qualify to teach in more ad vanced schools. Particularly interested in mathematics and continuing his interest in botany from the days of his tree-tending youth, Mendel combined the two in a hobby he made out of botanical research. For eight years, beginning in 1857, he grew peas in the monastery garden. Carefully he self-pollinated various plants, wrapping them to guard against accidental pollination by insects, making sure in this way that if any charac teristics were inherited they would be inherited from only a single parent. Carefully he saved the seeds produced by each self-pollinated pea plant, planted them separately, and studied the new generation. He found that if he planted seeds from dwarf pea plants, only dwarf pea plants sprouted. The seed produced by this sec ond generation also produced only dwarf pea plants. The dwarf pea plants “bred true.”
Seeds from tall pea plants did not al ways behave in quite this way. Some tall pea plants (about a third of those in his garden) bred true, producing tall pea plants generation after generation. The rest, however, did not. Of these, some seeds produced tall plants and some dwarf plants. There were always about three times as many tall plants produced by these seeds as dwarf plants. Apparently, then, there were two kinds of tall pea plants, the true-breeders and the non-true-breeders. Mendel went a step further. He crossbred dwarf plants with true-breed ing tall plants and found that every resulting hybrid seed produced a tall plant. The characteristic of dwarfness seemed to have disappeared. Next Mendel self-pollinated each hy brid plant and studied the results. They were all of the non-true-breeding type. About one quarter of the seeds of each plant developed into true-breeding dwarf plants. One quarter developed into true- breeding tall plants. One half developed into non-true-breeding tall plants. Apparently, non-true-breeding tall plants contained within themselves the characteristics of both tallness and dwarfness. When both characteristics were present, only tallness showed. It was dominant. Dwarfness, however, al though recessive and not visible, was not eradicated. When the characteristic ap peared in some plants in the next genera tion, unaccompanied by the tallness characteristic, the plants were dwarfs. In similar fashion Mendel studied characteristics other than height. He was able to show that in every case, mixtures of characteristics did not blend into in termediateness but retained their iden tity. He showed that pairs of charac teristics combined and sorted themselves out according to fixed and rather simple rules. Apparently both male and female parents contributed (equally) a factor governing each particular trait and the pairs of factors in the offspring did not blend but remained distinct. This was tremendously important (al though Mendel did not realize it). Dar
[638] MENDEL
ARREST [639] win’s [554] theory of evolution by natu ral selection had one overwhelming weakness. Darwin envisioned natural variations arising in each generation of a species, and natural selection seized upon those variations to preserve the good and doom the bad. But the action of natural selection was slow and if, in the mean time, through unrestricted and random mating, the varying characteristics melted into intermediacy, upon what would natural selection exert its effect? Mendel’s discovery that varying charac teristics did not blend but remained dis tinct showed that natural selection could work slowly and still effectively upon natural variation. Mendel might have pointed all this out, for he had read Dar win’s Origin of Species and was even in terested enough to annotate his copy. Nevertheless, when the time came for him to write up his experiments, he never mentioned Darwin. However, the world was not to know of this. Mendel wrote up the result of his experiments carefully, but when he read them to the local society of natural his tory, he made no impression at all. There was no discussion and no ques tions. Conscious of his own status as an unknown amateur, he felt it would be wise to obtain the interest and spon sorship of some well-known botanist. In the early 1860s, therefore, he sent his paper to Nâgeli [598], who was the near est of the prominent botanists of the time. Nâgeli glanced through the paper but apparently was repelled by the math ematics. He himself was a biologist of the old school and indulged in rather windy and obscure theorizations. A paper by an unknown monk with no theories but with only painstaking count ings and ratios seemed worthless to him. He returned it with brief and cold com ments, and this effectively chilled Men del. To be sure, Nâgeli offered to grow some of Mendel’s seeds, but he never did and the offer was probably not meant seriously. He did not answer Mendel’s later letters, and when Nâgeli wrote his major work on evolution twenty years later, he did not mention Mendel. Those were hard times. The Prussians, under the guidance of Otto von Bis marck, were rising to primacy in Europe and in 1866 they beat Austria in a whirl wind campaign of seven weeks. Not long before Prussian troops occupied Brünn, Mendel published his first paper in 1865 (followed by a second in 1869) in the Transactions of the Brünn Natural His tory Society. He then did no more re search for a variety of reasons. In the first place Nägeli’s cold reception had undoubtedly disheartened him as did the indifference of the naturalists in Brünn; in the second place he was appointed abbot of the monastery in 1868 and his administrative duties left him little spare time, particularly since he took up the cudgels against what he believed was dis criminatory tax legislation concerning religious institutions on the part of the Austrian government. Third, he put on weight and found it difficult to do the bending that was required in cultivating his peas properly. He kept up an ama teur interest in meteorology, maintaining careful records of the daily weather, as Dalton [389] had done a half century earlier.
Mendel’s work remained ignored and unnoticed. Few people looked through the rather obscure journal in which Men del’s paper appeared and those who did were either at home in botany but not in mathematics, or at home in mathematics but not in botany. In either case, they skipped over the paper. Darwin died in 1882, never knowing that the greatest weakness in his theory had been patched up. Mendel died in 1884, lonely and saddened, never sus pecting that he would someday be fa mous. Nägeli died in 1891, never dream ing what a terrible mistake he had made. In 1900 De Vries [792] came across Mendel’s paper, and what are now known as the Mendelian laws of inheri tance were finally brought to the notice of the scientific world, a full generation after their discovery. [639] ARREST, Heinrich Ludwig d’ (a-reh') German astronomer Born: Berlin, August 13, 1822 Died: Copenhagen, Denmark, June 14, 1875 419 [640] LEUCKART
HERMITE [641] Arrest, the son of an accountant of Huguenot descent (which accounts for his French name) entered the University of Berlin in 1839. He was working for his doctorate when Galle [573] under took to search for the trans-Uranian planet whose position Leverrier [564] had calculated. Arrest volunteered to help and sug gested that Galle use a particular star chart of the region in question, one that had been prepared but had not yet been published. Galle followed the suggestion and that night he called off the stars he observed while Arrest checked each, with its position, against the star chart. That very night, Neptune was discov ered, though Arrest’s share in the dis covery was not officially acknowledged by Galle until 1877. Arrest received his doctorate in 1850 and the next year published a book on the 13 asteroids then known. He discov ered several comets, the 76th asteroid (which he named after the Norse god dess Freia) in 1862 and studied nebulae. In 1858 he was appointed to a profes sorial position at the University of Co penhagen and became director of its newly established observatory. [640] LEUCKART, Karl Georg Frie drich Rudolf (loik'ahrt) German zoologist Born: Helmstedt, Braunschweig, October 7, 1822 Died: Leipzig, Saxony, February 6, 1898
Leuckart, the son of a printing plant owner, was strongly influenced by his uncle, who was a professor of zoology. He received his education at Gottingen, where he earned his medical degree in 1845. In 1850 he joined the faculty at the University of Giessen. In 1870 he transferred to the University of Leipzig, where he remained thereafter. Leuckart specialized in the study of the invertebrate phyla, carrying on where Lamarck [336] had left off. He clearly distinguished between the Coelen- terata (jellyfish) and Echinodermata (starfish) and showed that the fact that both displayed radial symmetry was not indicative of a close relationship. He then turned to the study of para sites and worked out the complicated life histories of tapeworms and flukes, found ing the modern study of parasitology. It was made quite clear by his work that there were human diseases (trichinosis, for instance) caused not by bacteria but by multicellular creatures of the various wormlike phyla. He published his studies on the parasites of man (in two vol umes) from 1862 to 1876. [641] HERMITE, Charles (ehr-meef) French mathematician Born: Dieuz, Merthe, December 24, 1822 Died: Paris, January 14, 1901 Hermite, the son of a cloth merchant, was born lame, a defect that may have hampered him socially, but not intel lectually. He did not do well at school, not even in mathematics. However, he was encouraged by Liouville [555], and in the end repaid the courtesy by com pleting one important aspect of Liou- ville’s work. This involved the concept of “al gebraic numbers”; numbers that could serve as solutions to polynomial equa tions of which x3 + x2 - | - x - ] - l = 0 is a very simple example. It was easy to show that any rational number and a great many irrational numbers such as \/2 and 5 + V3 could serve as solutions to some such equation or other. The question was whether there were any ir rational numbers that could not serve as solutions for such equations. Mathe maticians were certain there were, but proving it was another matter. Liouville had made the first step with respect to the important quantity e, with respect to certain polynomial equations. Hermite went on in 1873 to show that e could not be a solution to any conceiv able polynomial equation. It was not an algebraic number but a “transcendental number,” one that transcended (went beyond) the algebraic. Lindemann [826] was soon to find another and in the end it could be shown that there were infi
[642] PASTEUR
PASTEUR [642] nitely more transcendental numbers than algebraic ones. In 1876 Hermite became professor of higher algebra at the University of Paris and retained that position till his death. [642] PASTEUR, Louis (pas-teur') French chemist Born: Dole, Jura, December 27, 1822
Died: St.-Cloud (near Paris), September 28, 1895 As a youth Pasteur, the son of a tanner who was a veteran of the Napo leonic Wars, was not a remarkably good student, even though his father drove him on rigorously. He was interested in painting, showing considerable talent, in fact, and did moderately well in mathe matics. In chemistry he received the mark of “mediocre.” His ambition was to be a professor of fine arts. He strug gled against poverty by tutoring but even so underwent semistarvation at times. However, he attended the lectures of Dumas [514] and Balard [529] and, fired with enthusiasm, decided to enter chem istry. (This is an example of the impor tance of inspiring teaching, for although Dumas was an important scientist, Pas teur was to be a far greater one, and nothing in Dumas’s scientific life was more important than the setting of Pas teur’s feet on the proper road.) As Pasteur studied with increasing in terest, his place in class moved up steadily. After completion of his school ing, his first investigations were enough to show his true quality. These involved tartaric acid and related substances, and the manner in which they affected plane- polarized light (the existence of which had been explained by the transverse wave theory of light propounded by Fresnel [455] a generation earlier). Biot [404] had studied the manner in which the plane of polarized light was twisted when the light passed through quartz or through solutions of certain organic compounds. In some samples of a particular substance, the plane was turned clockwise; in other samples of the same substance, the plane was turned counterclockwise. The reason for this es caped Biot, however. In 1848—a year of successful revolu tion in France against King Louis Phi lippe—Pasteur himself took part on the side of the revolutionaries, although in general he was very conservative in his politics. Pasteur studied the crystals of tartrates (one of the substances that exhibited the now-clockwise, now-counterclockwise ef fect) under the microscope and found that the crystals were not all alike. They were rather subtly asymmetric and some of the crystals were mirror images of the others. The two crystals resembled each other as a right-hand glove resembles a left-hand glove. Pasteur had obtained his crystals from a solution that did not rotate the plane of polarized light, and he wondered if that was because the effect of one asym metric crystal was neutralized by the countereffect of its mirror image. Pains takingly, .with tweezers, Pasteur managed to separate the crystals into heaps. He dissolved the two heaps separately and behold, one solution twisted the plane of polarization clockwise and the other so lution twisted it counterclockwise. (It was possible to measure the twist very easily by the use of the Nicol [394] prism invented some years before.) This was a revolutionary discovery and it took some courage to announce it. A few years before, the well-known chemist Mitscherlich [485] had studied the same tartrate crystals and declared them all to be identical. Pasteur was only a twenty-six-year-old unknown. Never theless, he announced his findings and went before Biot to repeat his separation of the crystals before the eyes of the aged authority in the field and under his strict supervision. Biot was convinced and Pasteur received the Rumford medal of the Royal Society for this work. Ten years later Pasteur showed that a plant mold, growing in crystals of racemic acid, used only one variety. What was left was optically active. That was the first indication of a fact now accepted. Of two optical isomers, living tissue in variably uses only one. Pasteur had thus added importantly to Download 17.33 Mb. Do'stlaringiz bilan baham: |
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