39° 



SPECIFIC MICRO-ORGANISMS 



dents of rabies regard them as protozoa, while others consider 

 them to be products of cell degeneration. The evidence to de- 

 cide the matter is not yet at hand'. They "Beem to occur only in 

 rabies and to be constantly present in this disease. 



Pig. 153. — Section through the cornu ammonis of brain of a rabid dog; stained by 

 the method of Lentz. Five Negri bodies o£ different sizes are shown, enclosed within 

 the ganglion cells. The smallest contains only three minute granules. (^Afler Lenlz,' 

 Centralbl. f. Bakl, 1907, Abt. I, Vol. XLIV, p. 378.) 



Lyssa or rabies^ is primarily a disease of dogs but it occurs in 

 other mammals as well, usually as a result of dog bites. In ani- 

 mals inoculated directly into the brain with the most virulent 

 material (fixed virus), the symptoms of rabies appear in 4 to 6 

 days and death occurs on the seventh day. Inoculation with the 

 saliva or nervous tissue of a mad dog (street virus) rarely causes 



1 For a general discussion ol rabies see Cumming: Journ. A. M. A., 1912, Vol. 

 LVIII, pp. 1496-1499. 



