7 6S THE POPULAR SCIENCE MONTHLY. 



and of other organs. It is very common in the intestines, and is prob- 

 ably the beginning of putrefaction. 



Rabies is a canine disease which is communicated by a bite, and the 

 inoculation of man and other animals by the saliva. We are not yet 

 precisely acquainted with the microbe which causes the disease, but 

 Pasteur's recent researches have thrown considerable light on its life- 

 history, which is still, however, too much involved in obscurity. It 

 must first be observed that the hypothetical microbe of rabies, which 

 no one has yet discovered, should not be confounded with the microbe 

 of human saliva ; this is found in the mouths of healthy persons. 



The following conclusions are the result of Pasteur's researches 

 into the virus of rabies. 



This virus is found in the saliva of animals and men affected by 

 rabies, associated with various microbes. Inoculation with the saliva 

 may produce death in three forms : by the salivary microbe, by the 

 excessive development of pus, and finally by rabies. The brain, and 

 especially the medulla oblongata, of men and animals which have died 

 of rabies, is always virulent until putrefaction has set in. So also is 

 the spinal cord. The virus is, therefore, essentially localized in the 

 nervous system. Rabies is rapidly and certainly developed by trephin- 

 ing the bones of the cranium, and then inoculating the surface of the 

 brain with the blood or saliva of a rabid animal. In this way there is 

 a suppression of the long incubation which ensues from simple inocu- 

 lation of the blood by a bite or intravenous injection on any part of 

 the body. It is probable that in this case the spinal cord is the first 

 to be affected by the virus introduced into the blood ; it then fastens 

 on its tissues and multiplies in them. 



As a general rule, a first attack which has not proved fatal is no 

 protection against a fresh attack. In 1881, however, a dog, which had 

 displayed the first symptoms of the disease of which the other animals 

 associated with him had died, not only recovered, but failed to take 

 rabies by trephining, when reinoculated in 1882. Pasteur is now in 

 possession of four dogs which are absolutely secured from infection, 

 whatever be the mode of inoculation and the intensity of the virus. 

 All the other test-dogs which were inoculated at the same time died of 

 rabies. In 1884, Pasteur found the means of attenuating the virus. 

 For this purpose he has inoculated a morsel of the brain of a mad dog 

 into a rabbit's brain, and has passed the virus proceeding from the rab- 

 bit through the organism of a monkey, whence it becomes attenuated 

 and a protective vaccine for dogs. This is the first step toward the 

 extinction of this terrible disease. 



Glanders, again, is a disease easily transmitted from horses to man. 

 Glanders', or farcy, is caused by the presence of a bacterium, observed 

 as early as 1868 by Christot and Kiener, and more recently studied 

 at Berlin by Schtitz and Lofler. This microbe appears in the form 

 of very fine rods {bacillus) in the lungs, liver, spleen, and nasal cavity. 



