538 A MANUAL OF BACTERIOLOGY 



holding in its meshes large ganglionic cells with distinct 

 well-staining nuclei, each being enclosed in a capsule 

 lined with endothelium. The changes in rabies consist 

 in atrophy of the ganglionic cells, which become shrunken 

 and no longer fill the enclosing capsule, and their nuclei 

 at the same time become ill-defined and stain badly. 

 A number of new-formed cells also appear within the 

 ganglionic capsules. Ravenel and McCarthy studied 

 twenty- eight cases of rabies in various animals, and consider 

 that these capsular and cellular changes in the ganglia, 

 taken in conjunction with the clinical manifestations, 

 afford a rapid and trustworthy means of diagnosis of 

 rabies, but that the absence of these changes does not 

 necessarily imply that rabies is not present. They also 

 consider that the rabic tubercle of Babes is present suffi- 

 ciently often to furnish valuable assistance in cases where 

 the central nervous system only is obtainable. 1 



Pasteur showed that the virus can be attenuated by 

 desiccating the infective nerve matter, and in this way 

 was able to prepare a vaccine which protects animals from 

 otherwise fatal doses of the virus. Advancing a step 

 further, he used his vaccines to treat individuals who had 

 been bitten by rabid animals, but in whom the symptoms 

 had not yet developed, and so inaugurated the present 

 system of anti-rabic inoculation as carried out at the 

 Pasteur and other institutes. 



To prepare the anti-rabic vaccines, a rabbit is inocu- 

 lated subdurally with an emulsion made from the medulla 

 of a rabid dog. When the animal dies, a second rabbit is 

 similarly inoculated from the first, and the passage through 

 rabbits is continued until a " fixed " virus is obtained, 

 with which the first symptoms appear on the seventh or 

 eighth day, and which kills with certainty in about ten 



1 See Journ. Compar. Pathol. and Therapeut., vol. xiv, pt. i, 1901, 

 p. 37. 



