SCIENCE LETTER FROM PARIS. 657 



tagion, or a simple modification which gives place only to some phenomena hardly- 

 appreciable, but which nevertheless preserves the animals from the natural malady 

 which so ofter kills them. 



This species of preservation is called vaccination, on account of its analogy 

 with the vaccination of Jenner. It has proved efficacious in the case of the dis- 

 ease charbon, which attacks cattle and horses — the former especially, and sang de 

 rate in sheep. With man the disease is designated malignant pustule. 



These Observations will serve to introduce a still further discovery made by 

 M. Pasteur, in the case of the " red malady," or rouget, and which in the province 

 of the Rhine, carries off 20,000 pigs yearly, and those of the white, the most val- 

 uable breed, especially. M. Pasteur has found the microbe of the disease ; the 

 parasite has the form of a figure (8), and resembled the same found in hen chol- 

 era ; it is smaller and more difficult of detection, but its physiological properties 

 are different; thus it exercises no action on poultry, but kills rabbits and sheep. 

 The microbe artificially produced, when employed to inoculate pigs, induces the 

 same symptoms as if the scourge had been spontaneously produced. When vac- 

 cinated with a benign pus specially prepared, the pigs were able to resist the 

 the disease in its mortal form. However, it has been considered prudent to wait 

 till spring for the results of additional experiment. 



In the history of science, the spectacle has never been previously witnessed 

 of a single individual making so many discoveries in a period so relatively short 

 as Pasteur. He now gives us the results of his investigation into that terrible 

 problem — hydrophobia. It is the malady which presents the most obstacles for 

 inquiry. The saliva was the sole matter where the presence of the rabic virus 

 was to be detected. But this saliva, inoculated either by bite, or injection di- 

 rect into the cellular tissue, did not infallibly communicate the malady. Then 

 even if the latter did show itself, the period of incubation could not be exactly de- 

 termined. There were also other drawbacks. All these, ho.wever, were set at 

 rest by a new and sure plan of action. Pasteur found that the central nervous 

 system was the principal seat of rabic virus, and that it could be gathered there 

 in a state of perfect purity ; again, that this virus, taken from the surface of the 

 brain by trepanation, if inoculated, communicated the disease surely and rapidly. 



The symptoms of hydrophobia are variable, though proceeding from the same 

 virus, and these variations depend on the points of the nervous system — the spinal 

 marrow, or the brain, etc., where the disease may be localized and developed. 

 The saliva rabical contains microbes along with the virus, either of which caa. 

 produce death. The saliva of a man or a child,. can be virulent, is contagious, 

 and can kill by inoculation, from an excessive development of pus. The virus 

 of an individual affected with hydrophobia is everywhere characterized by the 

 same virulence, whether that virus be taken from the brain or the marrow, and 

 so long as decomposition has not set in. Pasteur has conserved a brain pending 

 three weeks with all its rabical virulence intact. Inoculating the surface of the 



