558 



FAMILY: TRYPANOSOMID^ 



an acute form that death takes place in a few days. The infection in the 

 goat is of a chronic nature, and the animal may recover. If, however, a 

 monkey is inoculated from the goat, as a rule no infection takes place, 



an experiment which proves 

 that passage through the goat 

 may profoundly modify the 

 virulence of a tryjianosome. 

 The loss of virulence of 

 T. peconi7H for the rat after 

 passage through the goat is 

 another instance of the same 

 change. These observations 

 are of considerable interest in 

 throwing light on the real value 

 of inoculation tests as a means 

 of separating trypanosomes 

 generally. 



Morphology. — T. simicB varies 

 in length from 14 to 24 mi- 

 crons; the majority of forms 

 measure about 18 microns, 

 and are thus larger than those 

 of T. congolense, which have 

 an average length of only 14 

 microns (Fig. 230). There is 

 no flagellum, but in some in- 

 dividuals there is a difficulty, 

 as occurs also with T. congo- 

 lense, in deciding whether the 

 last few microns represent a 

 flagellum or not. The nucleus 

 is central, while the kinetoplast 

 is at the margin of the try- 

 panosome, about 1-5 microns 

 from the posterior end, which 

 is generally more or less 

 rounded. As suggested by 

 Hornby (1921), it is possible 

 that T. siniice is merely a race of T. congolense modified by passage through 

 the wart hog. 



Transmission and Cycle in Tsetse Fly.— The transmission of T. simicB by 

 Glossina morsitans was demonstrated by Bruce et al. (1912) in Nyasaland, 



Fig. 231. — Trypanonoma simUc IN the IjABIUM 

 (left) and Hypopiiarynx (right) of Glossina 

 morsitans (x 520). (After Bruce, Harvey, 

 Hamerton, and Lady Bruce, 1913.) 



