INFECTIOUS DISEASES AND MICROBES, ETC. 185 



dialysed the pure saliva of rabid animals, and 

 proved that its solid constituents were always 

 virulent, and reproduced the disease when injected 

 into healthy animals, while the fluid portion, simi- 

 larly injected, remained inactive. If an alkaloid or 

 ptomaine had been present it would have been found 

 in the fluid portion, and would have given rise to 

 toxic effects when injected into the system. Al- 

 though a ptomaine has not been discovered in the 

 saliva of rabid animals, Dr. Anrep 1 isolated a 

 poisonous ptomaine from the brain and medulla 

 oblongata of rabbits suffering from rabies. This 

 ptomaine reproduced all the characteristic symp- 

 toms of the disease, and it is stated that a gradual 

 habituation of the animal to small doses of the 

 ptomaine produced a certain degree of immunity. 



Babies is not a disease of the blood, for the sup- 

 posed microbe is not found in the blood system, 

 and when the blood of a rabid animal is injected 

 into animals it does not reproduce the disease. In 

 fact, the virus is located in the nervous system, 

 especially the medulla oblongata. 



The period of incubation of rabies is usually not 

 less than from four to six weeks, and sometimes 

 longer. ' At the end of this incubation period the 

 wound, first of all, becomes slightly uncomfortable ; 

 there is itching, and the heat becomes almost 

 intolerable, especially as this is usually accom- 

 panied by a sharp stinging pain; the patient 

 becomes feverish and very thirsty; the face is 

 pallid and has a peculiar anxious expression, the 



1 British Medical Journal, 1889, p. 319. 



