148 MICROBES, FERMENTS, AND MOULDS 



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 tre- 

 phining the bones of the cranium, and then inocu- 

 lating 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 

 inoculation of the blood by a bite or in tra- venous 

 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 re-inoculated in 1882. 

 Pasteur is now in possession of four dogs which are 



