RABIES. 549 



gators in all parts of the scientific world. An examination of the 

 vitality of Negri bodies will show a striking resemblance to the 

 vitality of an emulsion of the virulent tissue. Thus, Negri bodies 

 have been found to be quite resistant to external agencies, such as 

 putrefaction, drying, etc., and are about the last portion of the nerve 

 cell to survive the advance of decomposition. They are also found in 

 over 96 per cent of the cases of rabies examined, but have not been 

 proved to exist in other diseases. 



Valenti states, a« his strongest evidence of the protozoan nature of 

 the bodies, that the virus of rabies is neutralized in test tubes by 

 quinin, while no other alkaloid has this property. As a result of the 

 work performed in the New York City board of health laboratory, 

 Park claims that Negri bodies are found in animals before the begin- 

 ning of visible symptoms, and evidence is given that they may be 

 found early enough to account for the infectiousness of the central 

 nervous system. These bodies are now almost universally considered 

 as diagnostic of rabies, and in the pathological laboratory of the 

 Bureau of Animal Industry their detection in the nerve cells of the 

 brain suffices for a diagnosis of rabies without animal inoculations. 

 In case these granular bodies are not found in a suspected animal, the 

 plexiform ganglion is next examined, and should negative results still 

 be obtained, the inoculation of rabbits is then made as a last resort. 

 It is indeed rare that positive results are obtained from the latter 

 method after the first two methods have been negative, but it has 

 occurred occasionally in cases where the animal had been killed in 

 the early stages of the disease. 



Symptoms. — From the moment of inoculation by the bite of a rabid 

 dog or other rabid animal or by other means, a variable time elapses 

 before the development of any symptoms. This time may be eight 

 days or it may be several months; it is usually about four weeks. 

 The first symptom is an irritation of the original wound. This 

 wound, which may have healed completely, commences to itch until 

 the horse rubs or bites it into a new sore. The horse then becomes 

 irritable and vicious. It is especially susceptible to moving objects; 

 excessive light, noises, the entrance of an attendant, or any other dis- 

 turbance will cause the patient to be on the defensive. It apparently 

 sees imaginary objects; the slightest noise is exaggerated into threat- 

 ening violence; the approach of an attendant or another animal, 

 especially a dog, is interpreted as an assault and the horse will strike 

 and bite. The violence on the part of the rabid horse is not for a 

 moment to be confounded with the fury of the same animal suffering 

 from meningitis or any other trouble of the brain. But in rabies 

 there is a volition, a premeditated method, in the attacks which the 

 animal will make, which is not found in the other diseases. Between 



