PASTEUR, pits'ter', Louis (1822-95). A celebrated French scientist, born at Dole. He early devoted himself to the study of chemistry and took his doctor's degree in 1847. In 1848 he became professor of physical science at Dijon, and in the following year accepted _the professor ship of chemistry at Strasshnrg. In 1854 he founded the faculty of sciences at Lille, of which he became dean. Here he remained until 1857, when he went to Paris as scientific director of the Ecole Normale Superieure and was elected a member of the Institute. In 1863 he became pro fessor of geology, physics, and chemistry at the School of Fine Arts, and from 1867 to 1875 was professor of chemistry at the Sorbonne. Later he carried on his researches at the institute bearing his name. The results of Pasteur's in vestigations have formed contribution- of the highest importance to nearly every branch of physical and natural science. By his classical researches on optically active substances and their separation into isomeric modifications of identical chemical but different physical prop erties. Pasteur became the founder of modern stereo-chemistry (q.v.). In the province of fer mentation and the germ theory his work was even more valuable. He showed that lactic, butyric, acetic, and other fermentations are caused by micro-organisms, and established on a firm scien tific basis the principle that spontaneous genera tion cannot take place, at least under ordinary conditions. The different of putrefac tion and fermentation set up by the air are in variably by germs the presence of which in the atmosphere Pasteur demonstrated by pass ing a current of air through guneotton. and dis solving the latter in a mixture of alcohol and ether: an insoluble residue was thus obtained, in which the germs of organisms could he readily seen with the aid of a miscroscope and could be shown to be capable of developing into mature organisms.
Pasteur's studies on the diseased conditions of wine and beer have rendered possible and easy the prevention of these conditions. No less important were his investigations on the silk worm's disease pc'brine and its cure. His dis covery of bacteria as the cause of anthrax (splenic fever in cattle was epoch-making in the science of diseases. Similar results were ob
tained with regard to fowl-cholera : and his ex periments show success in preventing the various diseases caused by septic bacteria, by inoculating animals with a milder form of the disease by means of a weaker brood of bacteria, artificially cultured. Pasteur found that by keeping a cultured crop of specific micro-organisms at a certain temperature with a full supply of oxy gen. he could reduce organisms to an incapacity for producing spores. therefore to sterility. But before this point is reached the cultured organ ism loses its virulence. although still germinat ing.: vaccination with it then produces a mild disease. which effectually protects from the fatal scourge of splenic fever, of fowl's cholera, and other diseases.
In the same manner he dealt with splenic apoplexy. which he showed to be caused by the presence of specific bacteria in the blood. By artificially cultivating these bacteria he suc ceeded in developing a weaker crop of germs: and by inoculating healthy animals with the virus lie produced a milder form of the disease. which is believed to afford protection from the more violent and dangerous malady. Pasteur's well-known treatment of hydrophobia (q.v.) is based on a similiar principle.
His published works include: Yourci exemple de fermentation par des animalcubs infusoires pourant rirre sans o.rum'ne lib re (1863) : Etudes stir le ring ses maladies, rausis qui les proroquent. etc. (1QM11 : Find. s .cur lr rinaigre, ses maladies. mom its pri rc '1 r, etc. (1868) : Etudes stir la maladie des rrrs sole (1870); ourcito s ,ur lu maladie des rers d soic, etc. (1671); Eludes sur in hu re, sis ete. 1 KG ; Lis microlas (jointly with Tyndall t : .sur 1(s maladies ntcs et ca particulitr rue hr maladi( rulgaircment etal. ra poilbs ( Paris, Issoi ; and several important article. in the .innoh o: d. Chintic. Consult: Bournand, ("a Went* a l'humanit(:: Pasteur, SO .1/4011 Part-. 1S9(i), and a Life in English by lir. and Mr-. Percy Frankland New York, 1`39:,