DR. LOUIS PASTEUR 883 Having attenuated the virus of these bacilli, Pasteur began a series of expert- ments to determine whether the attenuated virus could be intensified until its former venom was obtained. This he succeeded in, and thus discovered what is probably the key to the solution of the problem of the periodicity of epidemics of contagious diseases, such as cholera. In 1882 Pasteur's attention was called to a new disease, swine fever (rouget), which was ravaging the herds of- swine in France. He found the microbes, attenuated them, vaccinated the pigs, and se- cured the most favorable results. He also discovered that by passing the microbe of a disease through an animal not subject to that disease, he attenuated it so far as its effects on another were concerned. It was in 1880 that Pasteur first began his experiments in hydrophobia Se- curing the saliva of a child suffering from the disease, he inoculated rabbits with it and they died in thirty-six hours. He examined the saliva and the blood of the rabbits, and found in both a new microbe (a minute disk having two points). He established by repeated experiments that hydrophobia is a disease of the nerves, that a portion of the medulla oblongata, or of the spinal cord, is very much more certain to produce the disease, when introduced into the blood or placed on the brain, than is the saliva. He succeeded at last in isolating the mi- crobe, in making cultures of it, and then attenuating it, and in May, 1884, he pro- duced before a commission appointed by the Minister of Public Instruction the following results : Of six dogs unprotected by vaccination, three died as the results of bites of a dog violently mad. Of eight unvaccinated dogs, six died after extra-venous in- oculation of rabic matter. Of fiye unvaccinated dogs, all died after inocula- tion, by trepanning, of the brain with rabic matter. Of twenty-three vaccinated dogs, not one was attacked with the disease after inoculation, in any fashion, with the most virulent rabic matter procurable. During his long and busy life Louis Pasteur has been honored after every fashion known to men. He has opened the gates of knowledge wider than they were ever opened before, and in his discovery of the germs of disease, and in his still more wonderful discovery of the possibility of attenuating those germs and converting them into vaccines, he has revolutionized all ideas of physiology. He is one of the greatest pioneers in science that has ever lived, and his work will make his name illustrious so long as men shall continue on this earrh. The lesson of his life is the supreme value of experiment ; for, as was once said of him by Professor Dumas, " Pasteur is never mistaken, because he never asserts anything he cannot show another man how to prove."
