420 MICROBIOLOGY 



tending along the rim of the host-cell nucleus, or along one 

 of the nerve fibrils, as if moving there ; with eosin and methyl- 

 ene-blue they take a delicate light magenta stain, very similar 

 to that taken by the small serum globules in the blood vessels. 

 Many of the organisms, however, show a small chromatin 

 granule, situated more or less eccentrically, sometimes on the 

 very rim of the body. In the larger forms the granule is large, 

 in the smaller it can not always be seen; some of the larger 

 forms show from two to several granules and occasionally they 

 show a definite central body and the small granules about it. 



In this laboratory rabbits were inoculated with the brains 

 of 60 suspected cases (mostly dogs) of rabies in which Negri 

 bodies could not be found. In every case the results were 

 negative. On the other hand, every animal that has been 

 inoculated with the brains containing these bodies has died of 

 rabies. 



Diagnosis. The methods recommended by the committee 

 of the laboratory section of the American Public Health Asso- 

 ciation for the diagnosis of rabies - are given in detail. 



The most striking feature of rabies, in the dead animal, 

 is the absence of recognizable gross changes. This restricts the 

 diagnosis to the microscopic findings or to other laboratory 

 methods. As the diagnosis of the disease is to be made in the 

 laboratory, the method consists of two parts: (1) the procur- 

 ing of the suspected animals in a condition suitable for diag- 

 nosis and (2) the technique employed. 



(1) The results of the numerous investigations into the 

 nature and diagnosis of rabies have demonstrated that all the 

 structures necessary for a positive diagnosis are included in 

 the brain and the nerve ganglia of the head. This necessitates 

 sending to the laboratory the head only of the suspected ani- 

 mal. The head should be removed close to the body, packed in 

 ice, and sent directly to the laboratory as quickly as possible. 



(2) The laboratory diagnosis of rabies is restricted, for 

 all practical purposes, to three procedures, namely : 



a. Inoculation of experimental animals. 

 3 Jour. Am. Pub. Health Asso., Vol. I (1911) p. 420. 



