PROTOZOA 



399 



found it in the blood taken from other parts of the body. They 

 state that the best time to find the parasite in the placques is 

 on their first appearance. As the cutaneous lesions spread the 

 parasite becomes more difficult to find. Mohler 6 concludes 

 that Tr. equiperdum are fewer in 

 number and not so virulent in the 

 dourine of the United States as 

 they are in countries where the dis- 

 ease is indigenous. Watson 7 in a 

 study of dourine concludes that it 

 is in the early stages of infection 

 that the trypanosomes are most 

 active and numerous in the genital 

 organs and that as the disease ad- 

 vances or as the animal becomes 

 tolerant or indifferent to it the 

 parasites disappear from these re- 

 gions. 



Morphology. Tr. equiperdum 

 when examined in fresh blood from 

 infected animals is quite actively 

 motile. It is somewhat spindle 

 shaped. It varies in size from 22 

 to 30 /x in length and from 1.2 to 

 2.0 fjt. in width. The posterior ex- 

 tremity is bluntly truncate. The 

 head end is prolonged into a wavy 

 whip-like flagellum, giving it the appearance of a tail. Along 

 one side is a wavy, undulating membrane terminating in a 

 fiagellum. The nucleus is rather large and located centrally. 

 The centrosome from which the undulating membrane and the 

 fiagellum start is in the posterior part. It is readily stained 

 with Borrel's blue, or by Giemsa's azur-eosin stain. 



Fig. 87. 

 equiperdum 

 pig. (After 

 Mayer). 



Trypanosoma 



from guinea 



Nocht and 



6 Mohler, loc. cit. 



' Watson. Kept, of the Vet. Director-General and Livestock 

 Commissioner, Dept. of Agric., Ottawa, Canada, for the year ending 

 Mar. 31, 1910, p. 60. 



