PROTOZOA 421 



b. The determination of the changes in the ganglia as 



described by Van Gehuchten and Nelis. 3 



c. The presence of Negri bodies. 



Inoculation. In the animal inoculation method rabbits 

 are to be preferred, although guinea pigs may be used. They 

 should be inoculated with the suspected brain, preferably sub- 

 durally, although intraocular and intramuscular inoculation 

 cannot be entirely excluded. The diagnosis by this method is 

 not recommended, except in case of failure by the other meth- 

 ods, and where a late determination will be of value. 



Van Gehuchten and Nelis method. The diagnosis by 

 means of the changes in the Gasserian ganglia, described by 

 Van Gehuchten and Nelis, has proved to be very satisfactory 

 where the suspected animal has died or was killed in the late 

 stages of the disease, or when Negri bodies cannot be found, or 

 cannot be looked for because of destruction of brain, putrefac- 

 tion, etc. When sections are made from the ganglia removed 

 during the first stages of the disease, the apparently specific 

 lesions are often absent or not sufficiently well marked to war- 

 rant a diagnosis. The technique required for this procedure is 

 simply that of ordinary pathological histology. The changes 

 may be of two kinds : 



The typical, or focal lesions. These are characterized by 

 the partial or complete destruction of the ganglion cells, their 

 place being occupied by cells of the endothelial type. The foci 

 may consist almost entirely of cells of the endothelial type, but 

 often associated with them are mast cells, lymphocytes, plasma, 

 and connective tissue cells, and polymorphonuclear leucocytes. 



The atypical, or diffuse lesions. These are characterized 

 by a more or less general infiltration between the ganglion cells 

 and nerve fibres of cells of an endothelial origin and the 

 various cells which are associated with chronic inflammatory 

 processes. These changes are usually associated with the 

 typical lesions. 



The lesions in the ganglia may be very extensive, involving 



"^Van Gehuchten and Nelis. Ann. de Med. Vet., Vol. XLIX (1900) 

 p. 234. 



