ELEVENTH ANNUAL YEAR BOOK— PART X 537 



The nervous system offers the most favorable condition for the 

 development of the virus. The blood does not contain the infective 

 material, according to all experiments with the blood of infected 

 animals. The qontagion is not volatile. Paul Bert, by filtering the 

 saliva of rabid dogs' through plaster of paris plates and proving it 

 innocuous, showed that the infecting matter is a solid body. He 

 did not succeed in cultivating these bodies, which he regarded as 

 neither micrococci or bacilli. Negri has recently discovered the 

 causative agents of rabies in the shape of protozoa of various forms 

 situated in various parts of the brain. The vitality of the con- 

 tagion is great. Pasteur observed the brain of rabid clogs for three 

 weeks under very low temperature, without the infective matter 

 losing its virulence. Galtier found that buried cadavers remained 

 virulent from fifteen to forty-four days, despite putrefaction. Viola 

 holds that the contagium of rabies remains active over five months 

 when kept cool in a vacuum. 



The disease is transmitted directly by the bite of rabid animals, 

 the saliva serving as the vehicle of contagion. Absorption of con- 

 tagium in the digestive tract by the consumption of the flesh, milk 

 or saliva of infected animals, is regarded as doubtful. The injec- 

 tion of these substances have produced no harmful results. A fox 

 was fed two months on the brain and spinal chord of twelve rabid 

 dogs without any ill results. However, the intracranial inocula- 

 tion of milk of rabid animals has produced rabies. 



Virus injected into the body may remain dormant for a long 

 time at the site of bite, or may enter the body via the circulation, 

 or along nerves. The period of incubation is longer than in other 

 infective diseases, and in dogs average from three to six weeks, 

 with a maximum of several months, and a minimum of only a few 

 days. 



Most domestic and wild animals are subject to the disease. 



Post mortem changes in rabid animals are neither constant nor 

 specific. General, though not typical, changes are as follows; Ema- 

 ciated cadavers become rapidly putrid, and in large animals the 

 hind part becomes greatly distended by gas. The blood is thick 

 and dark-red in color. Mucous membrane of the mouth is congested 

 and swollen, chiefly at the base of the tongue. Muscles appear 

 granular and affected, with fatty degeneration. The heart, liver 

 and kidneys show parenchymatous degeneration. The tonsils are 

 enlarged and infected. The membrane of the pharynx and larynx 

 is reddened, swollen and studded w T ith small hemorrhages. Foreign 



