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606 [948] LEISHMAN
PLASKETT [949] for neither the sugar being fermented, nor the alcohol and carbon dioxide pro duced, nor the enzyme itself contained phosphorus. Since the inorganic phosphate disap peared, Harden searched for some or ganic phosphate formed from it and lo cated it in the form of a sugar molecule to which two phosphate groups had be come attached. In the course of fermen tation it was formed and then after many other reactions had taken place, the phosphate groups were removed again. This was the beginning of the study of intermediary metabolism, the search for the numerous compounds formed as in termediates (sometimes very briefly lived ones) in the course of the chemical reac tions going on in living tissue. It is now one of the liveliest and most important branches of biochemistry. Furthermore, Harden’s work led the way to the gradual realization by bio chemists that phosphate groups play an essential role in every phase of biochem istry. This culminated, a generation later, in the work of the Coris [1192, 1194], who finally worked out the fine details of fermentation, and in the development of the concept of the high-energy phosphate bond by Lipmann [1221], In 1912, Harden became professor of biochemistry at the University of Lon don. For his work in fermentation he shared the 1929 Nobel Prize in chemis try with Euler-Chelpin. In 1936 Harden was knighted. [948] LEISHMAN, Sir William Boog (leesh'man) Scottish physician Born: Glasgow, November 6, 1865
Died: London, England, June 2, 1926
Leishman, the son of a professor, graduated from the University of Glas gow in 1886 and then went into army service, finally reaching the rank of lieu tenant-general in 1923. He was shipped overseas to India where he remained from 1890 to 1897 and where he had ample opportunity to study tropical dis eases. In particular, he grew interested in one called kala-azar and in 1900 detected the disease agent, which turned out to be a protozoon. The disease is now sometimes called leishmaniasis. In 1903 he became professor of pathology at the Army Medical School and during the following decade he developed a vaccine against typhoid fever that was used during World War I and was credited with reducing the incidence of the disease. He was knighted in 1909. [949] PLASKETT, John Stanley Canadian astronomer
ber 17, 1865 Died: Esquimalt, British Colum bia, October 17, 1941 Plaskett, the son of a farmer, was a high school dropout. In 1889 he was a mechanic in the department of physics at the University of Toronto and began to take undergraduate courses and gradu ated in 1899. In 1903 Plaskett joined the staff of the new Dominion Observatory in Ottawa, and with his background in mechanics he was able to get the most out of the in struments. He pushed the Canadian Par liament ceaselessly for funds to build a 72-inch reflecting telescope, to be built according to his own design, and he finally had his way. Using it, after it was put into action in 1918, Plaskett discovered in 1922 that a star which had been thought to be single was actually a binary with each member of the binary unusually massive. Known as Plaskett’s twins, for half a century they remained the most massive known stars. He also noted spectral lines of calcium that did not partake of the usual shift in the stellar spectra and that were the stronger the more distant the star. He maintained, independently of Hartmann [940], that this calcium arose from in terstellar matter, and as it turned out he was correct.
[950] GOMBERG
WASSERMAN [951] [950] GOMBERG, Moses Russian-American chemist
grad), Ukraine, February 8, 1866 Died: Ann Arbor, Michigan, Feb ruary 12, 1947 In 1884 Gomberg and his family were forced to leave Russia, for his father had been accused of anti-tsarist activity. Rus sia was, in any case, not a comfortable land for members of the Jewish faith in those days. The family settled in Chicago and young Gomberg, whose high school edu cation had been interrupted, completed it in the new land, then went on to the University of Michigan where he ob tained his Ph.D. in 1894. He traveled to Germany for postdoc torate research, working in Baeyer’s [718] institute in Munich and under Vik tor Meyer [796] at Heidelberg. Under Meyer he decided to try to prepare tet raphenylmethane, a compound in which four rings of carbon atoms are all at tached to a single central carbon atom. Meyer himself had tried to hang all this weight upon a single carbon atom and had failed. He suggested that Gomberg try something else, but the young man had his mind made up and succeeded. He prepared tetraphenylmethane; not much, to be sure, but enough to study. When he returned to the University of Michigan, he took the next step, which was to prepare hexaphenylethane, in which six rings of carbon atoms are at tached to two adjoining carbon atoms in the center, three rings to each carbon atom. Here he failed. He did, however, obtain a compound that was very reac tive and that was strongly colored in so lution. (Hexaphenylethane, it was quite certain, would, when prepared, be color less and quite unreactive.) Gomberg was astonished and in 1900 was forced to conclude that he had half molecules, a single carbon atom with three rings attached, which he called triphenylmethyl. Carbon has four valences, according to the Kekule [680] scheme of structure, and since in tri phenylmethyl only three valences of the central carbon atom are in use, the fourth must hang loose, so to speak. A molecule with such an unfilled valence bond is called a free radical and Gom berg had isolated the first example of this sort of substance. This was by all odds the crowning achievement of his life (although later on he also developed the first satisfactory antifreeze for automobile radiators). As the twentieth century progressed, it dawned on chemists that free radicals are extremely important in chemical re actions. Most of them are far more fugi tive than Gomberg’s triphenylmethyl, but the manner in which they are formed and destroyed helps determine the nature of the reaction. One of the virtues of Pauling’s [1236] theory of resonance, ad vanced a generation after Gomberg’s dis covery, was that it could explain just why triphenylmethyl should be so unu sually stable for a free radical, so stable that it could actually be isolated in solu tion and last long enough to be studied. In 1927 Gomberg was made head of the department of chemistry at Michigan and he remained in that position until his retirement in 1936. Gomberg never married and would not allow his graduate students to marry until after they had obtained their de gree.
[951] WASSERMAN, August von (vahs'er-mahn) German bacteriologist
ary 21, 1866 Died: Berlin, March 16, 1925 Wasserman, the son of a banker, ob tained his medical degree at the Univer sity of Strasbourg in 1888 and for a time worked under Koch [767]. His research in immunology reached a climax in 1906, when he developed a diagnostic test for syphilis that is still known as the Wasserman test. This is based on Bor det’s [986] discovery of complement fixa tion. The subject’s serum is allowed to react with certain antigens and if the antibody to the syphilis microorganism (discov ered the year before by Schaudinn 6 0 8
[952] LEBEDEV
STARLING [954] [997]) is present the reaction takes place and complement is used up. The key portion of the test is then to test for the presence of complement. Its absence is indicative of syphilis; its presence means that it was not used up and therefore no syphilis, or its antibody, was present. In 1913 Wasserman was appointed di rector of the Kaiser Wilhelm Institute in Berlin-Dahlem. [952] LEBEDEV, Pyotr Nicolaievich (lay'beh-dev) Russian physicist Born: Moscow, March 8, 1866 Died: Moscow, April 1, 1912 Lebedev, the son of a merchant, was unable to enter a Russian university, so he obtained his graduate training in Ger many under Kundt [744] and Helmholtz [631], obtaining his doctor’s degree in 1891. After returning to Russia he was appointed professor of physics at the University of Moscow in 1892 but re signed in 1911 in protest against tsarist oppression of education. He was interested in the possibility that light might exert pressures. This had been predicted by Maxwell’s [692] equa tions and it was a possible explanation, for instance, of the fact that comets’ tails always pointed generally away from the sun whether the comet was approaching the sun or receding. In 1901, using very light mirrors in a vacuum, Lebedev was actually able to observe and measure the pressure exerted by light, again con firming Maxwell’s theories, as well as providing a vehicle for Arrhenius’ [894] life spores. [953] MILLER, Dayton Clarence American physicist
13, 1866 Died: Cleveland, Ohio, February 22, 1941 Miller, the son of a shopkeeper, gradu ated from Baldwin-Wallace College, ob tained his Ph.D. at Princeton University in 1890, and was appointed professor of physics at the Case School (now Case Western Reserve University) in Cleve land, where he remained till his death. Michelson [835] and Morley [730] had conducted their famous experiment on the speed of light the decade before and Miller worked with Morley to check the results under even more delicate condi tions. This work, carried out from 1902 to 1904, confirmed the Michelson- Morley results. However, Miller was unwilling to ac cept Einstein’s [1064] theories that arose out of the experiment and continued to search for some positive evidence of “ether-drift,” which would make relativ ity invalid. In 1921 he thought he had it but that turned out to be a false alarm. He obtained more positive results in venting a photodeik in 1912, a device whereby the oscillations of sound waves were visualized when they were made to cause vibrations in a mirror that in turn induced vibrations in a spot of reflected light. By this means he was able to study musical sounds in detail and, in effect, to make musicology a science. [954] STARLING, Ernest Henry English physiologist
maica, May 2, 1927 Starling, the son of a lawyer, obtained his medical degree in 1890 and in 1900 became professor of physiology at Uni versity College in London. In the 1890s he did important work on the function ing of the heart and on the interrela tionship of the blood and lymph. In 1912 he published a standard text on physiology. His most memorable work, however, turned out to have its chief influence in biochemistry. With Bayliss [902] he was studying in 1902 how the pancreas began to secrete its digestive juice as soon as the acid food contents of the stomach entered the intestine. According to Pavlov [802] this was nerve con trolled. However, when Starling and Bayliss cut the nerves to the pancreas, it
[955] LAZEAR
NICOLLE [956] still performed on cue. They discovered that the lining of the small intestine se creted a substance (which they named secretin) under the influence of stomach acid, and it was this secretin that stimu lated the pancreatic flow. Eventually Starling suggested a name for all sub stances discharged into the blood by a particular organ for the purpose of rous ing some other organ or organs to activ ity. This was “hormone,” from Greek words meaning to “rouse to activity.” Some years before, Takamine [855] had isolated the first pure substance that eventually was to be recognized as a hor mone. The way was open to recognition of the fact that hormone malfunction was a cause of disease. Two decades later, Banting [1152] was to show how this new knowledge could be used to great advantage in medicine. During World War I, Starling worked on defenses against poison gas, and then served as scientific adviser to the Minis try of Food. [955] LAZEAR, Jesse William (luh- zeerO
American physician Born: Baltimore County, Mary land, May 2, 1866 Died: Quemados, near Havana, Cuba, September 25, 1900 Lazear graduated from Johns Hopkins University in 1889 and went on to earn his medical degree at Columbia Univer sity in 1892. He joined the staff of Johns Hopkins and studied the malarial para site. In 1900 he was named acting assis tant surgeon in the United States Army and was sent to Cuba with Reed [822]. When the group turned from their vain attempt to find a bacterial agent and began to study mosquitoes, Lazear was put in charge of the insects. He did not intend to experiment on himself as his fellow investigator, Carroll [849], had done, but when a mosquito lit on his arm, he allowed it to bite him and was dead of yellow fever within a week. Lazear is the classic case of the medical martyr.
[956] NICOLLE, Charles Jules Henri (nee-kole') French physician Born: Rouen, Seine-Mame, Sep tember 21, 1866 Died: Tunis, Tunisia, February 28, 1936
Nicolle was the son of a physician and he followed in his father’s footsteps, ob taining his medical degree in 1893 and then joining the faculty of the medical school in Rouen where his father was a professor. He had taken a course in microbiology at the Pasteur Institute during his education and in that direc tion lay his important work, though he also tried his hand at novel writing. In 1902 he was appointed director of the Pasteur Institute in Tunis and it was there, in a colonial area (as was true of so many physicians around the turn of the century, Reed [822] and Leishman [948], for example), that he had a par ticularly good opportunity to study a cer tain disease. In this case, it was typhus fever, which Ricketts [992] was to study in the western hemisphere with tragic re sults. In Tunis, Nicolle noticed an interest ing thing. Typhus was very contagious outside the hospital, spreading on con tact. Doctors visiting patients caught it; hospital employees who admitted the pa tients caught it. However, once the pa tient was actually in the hospital and under observation, typhus was no longer contagious. Nicolle decided that the cru cial point was at the entrance into the hospital, when the patient was stripped of his clothes and scrubbed down with soap and water. Whatever transmitted the disease was in the clothes, then, and was removed from the body by washing. His suspicion fell on the body louse. He began to work with animals, first chimpanzees, then guinea pigs, and proved the case. As mosquitoes trans mitted malaria and yellow fever, so the louse transmitted typhus. Unfortunately it is not as easy to get rid of a tiny body parasite as it is to get rid of the free- flying insect, and typhus remained a great killer in World War I. It was Müller [1216] and his discovery of DDT
[957] MORGAN
MORGAN [957] that turned the trick and just about wiped out typhus among World War II troops.
Nicolle also demonstrated that animals might sometimes carry a disease in mild form, displaying virtually no symptoms yet remaining infective. This explained how diseases remained in existence be tween epidemics. It was there all the time, and the epidemic was merely the result of a periodic increase in virulence. The reason for such changes in virulence came when men like Beadle [1270] ex tended the De Vries [792] concept of mutation to microorganisms. [957] MORGAN, Thomas Hunt American geneticist Born: Lexington, Kentucky, Sep tember 25, 1866 Died: Pasadena, California, De cember 4, 1945 Morgan, the nephew of a Confederate general and a descendant, through his mother, of Francis Scott Key (who wrote the words to “The Star-Spangled Banner”), graduated from what is now the University of Kentucky in 1886 and obtained his Ph.D. from Johns Hopkins University in 1890. A year later he joined the faculty of Bryn Mawr College, where he came under the influence of Loeb [896], In 1904 he became professor of experimental zoology at Columbia University. During his decade at Bryn Mawr, ge netics had come into being. Mendel’s [638] work had been rediscovered by De Vries [792] and at once several people suggested that the chromosomes’ behav ior during cell division and egg forma tion just fit the behavior of the genetic factors according to Mendel. However, there were only some two dozen pairs of chromosomes in the human cell. Surely they could not account for the thousands of characteristics inherited by human children, unless each chromosome con tained large numbers of different factors. The separate factors were called genes, from a Greek word meaning “to give birth to.” But since Flemming’s [762] work, a quarter century earlier, made it clear that chromosomes were inherited as units, the characteristics controlled by the genes on each chromosome should be inherited together and not indepen dently. (Mendel had discovered that characteristics were inherited indepen dently, but he had dealt with only seven characteristics and each of these, by a stroke of coincidence, had been con trolled by genes on separate chromo somes. ) The problem, now, was to check this question of “gene-linkage” experi mentally. In 1907 Morgan, who had at first doubted the validity of Mendel’s theories, made the necessary advance, the discovery and utilization of a new bi ological tool. He began work with a tiny insect called Drosophila, the fruit fly. It was a small insect, capable of being bred in large numbers with virtually no trou ble; it multiplied like wildfire and its cells possessed only four pairs of chro mosomes.
The problem of inheritance was thus reduced to simple terms, and by follow ing the generations, Morgan discovered numerous cases of mutations (which demonstrated De Vries’s theory in the animal kingdom as well as in the plant kingdom) and showed that various char acteristics were indeed linked, that is, inherited together, as though the genes involved occurred on the same chromo some. And yet linked characteristics were not eternally linked. Every once in a while each was inherited separately. This was correlated with the fact that pairs of chromosomes occasionally switched por tions (“crossing over”) so that the integ rity of an individual chromosome was not absolute. These experiments definitely es tablished the chromosomes as carriers of heredity and strongly backed the gene concept. It was even possible to locate the spot on the chromosome at which a particular gene might exist. The greater the length of chromosome separating two genes, the greater the likelihood that crossing over at a random spot would separate the two. By studying the fre quency with which two particular linked Download 17.33 Mb. Do'stlaringiz bilan baham: 
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