Dourine. 521 



apparently recovered case will relapse under its frequent repetition. 

 The abrasion of the epithelial surface also forms infection atria 

 and favors new multiple points of infection. 



The disease has occurred congenitally (Rodolff, Jessen). It 

 has been claimed that the higher bred horses with lighter frames 

 are the more susceptible (Fischer), but this is probably a delusion, 

 the disease having been often introduced by the Barb and Arabian 

 and propagated among their grade descendants. The heavy Per- 

 cheron shows a very ready susceptibility and a virulent and fatal 

 form of the affection. 



Microbiology. That the affection was due to a microbe was 

 clearly shown by its absence from every part of the world into 

 which infected horses had not been brought. The secluded 

 countries, Belgium, England, Scandinavia, that breed their own 

 horses, the distant Au.stralia, New Zealand and South America 

 remained free in face of the con,stant presence of the infection in 

 different parts of Central and Southern Europe, in Africa and 

 Asia. The horses of America and South Africa showed a ready 

 susceptibility to the virus brought by infected horses, and rigorous 

 sanitary police control speedily cleared a district of the trouble. 



Thanhoffer found in the blood, vaginal mucous, testicle, semen, 

 spinal fluid, myelon, and roots of the dorsal and lumbar nerves 

 cocci, especially streptococci and less constantly bacilli, to which 

 he attributed the malady. More recently Schneider and Buffard 

 have apparently demonstrated that an infusorian, the trypanosoma 

 of dourine, is the essential pathogenic agent. 



The Trypanosoma Equiperdum varies greatly in form at differ- 

 ent stages of its growth or in different media. In the exudate of 

 the slight early tumefaction, without as yet other symptoms, it is 

 found as minute granules in groups, as larger spherical very re- 

 frangent bodies like very large cocci, each having a strongly 

 staining nucleus, and as larger bodies in which a delicate mem- 

 branous covering encloses one, two or three masses of chromatin 

 and extends to form one or more points (club-shaped or fusi- 

 form). Each chromatin mass has a nucleolus on its outer surface 

 or slightly apart from it. Twenty-four hours later there may be 

 added : First, short, thick chromatin bodies, with two slightly 

 undulating, pointed, membranous prolongations. Second, more 

 delicate, fusiform bodies, each with one chromatin nucleus, a de- 



