614 HYDROPHOBIA 



limbs with virulent material. If now the animal be killed 

 before symptoms have manifested themselves, rabies can be 

 produced by subdural inoculation from the nerves of the limb 

 which was infected. Further, rabies can often be produced from 

 such a case by subdural infection with the part of the spinal 

 cord into which these nerves pass, while the other parts of the 

 animal's nervous system do not give rise to the disease. This 

 explains how the initial symptoms of the disease (pains along 

 nerves, paralysis, etc.) so often appear in the affected part of the 

 body, and it probably also explains the fact that bites in such 

 richly nervous parts as the face and head are much more likely 

 to be followed by hydrophobia than bites in other parts of the 

 body. Again, injection into a peripheral nerve, such as the 

 sciatic, is almost as certain a method of infection as injection 

 into the subdural space, and gives rise to the same type of 

 symptoms as injection into the corresponding limb. Intravenous 

 injection of the virus, on the other hand, differs from the other 

 modes of infection in that it more frequently gives rise to 

 paralytic rabies. This fact Pasteur explained by supposing 

 that the whole of the nervous system in such a case becomes 

 simultaneously affected. In certain animals the virus seems to 

 have an elective affinity for the salivary glands, as well as for 

 the nervous system. Roux and Nocard found that the saliva of 

 the dog became virulent three days before the first appearance 

 of symptoms of the disease. 



The Virus of Hydrophobia. While a source of infection 

 undoubtedly occurs in all cases of hydrophobia, and can usually 

 be traced, all attempts to determine the actual morbific cause 

 have been unsatisfactory. In this connection various organisms 

 (yeasts, diphtheroid bacilli) have been described as being 

 associated with the disease, but none of these have been shown 

 to possess the capacity of producing immunity against the 

 ordinary hydrophobic virus. 



In 1903, Negri described certain bodies as occurring in the 

 nervous system in animals dying of rabies to which much 

 attention has since been devoted, and regarding the significance 

 of which opinion is still divided. As Negri's observations have 

 been generally confirmed, and as it is probable that the 

 occurrence of the bodies is specific to the disease, and that their 

 recognition is of value for diagnosis, we shall describe the 

 methods of their demonstration. 



The method of Williams and Lowden is to take a piece of the brain 

 tissue, to squeeze it between a slide and cover-glass, and, sliding off' the 

 latter, to make a smear which is then fixed in methyl-alcohol for five 



