620 



TRYPANOSOMIASIS 



trypanosome as the cause of nagana, and this has since been finally 

 established by the origination of the disease by artificial cultures 

 of the organism. 



The Tr. Brucei (Fig. 171), according to Laveran, measures in 

 the horse from 28 to 33 //.long and from 1'5 to 2 '5 /x broad; 

 in the rat and dog it is somewhat shorter. It is motile, but its 

 activity is less than that of Tr. Lewisi. When stained it presents 

 the usual appearances; its posterior end is usually blunt, and 





FIG. 171. Trypansoma Brucei from blood of infected rat. Note in 

 two of the organisms commencing division of micromicleus and undu- 

 lating membrane, x 1000. 



the body often contains granules in the anterior portion of its 

 protoplasm. It divides longitudinally, and, accordng to Brad- 

 ford and Plimmer, a form of longitudinal conjugation occurs in 

 the blood. According to the same observers, it can be kept alive 

 for five to six days in blood outside the body. It is less resistant 

 to the action of cold than Tr. Lewisi, perishing in a few days 

 at 5 to 7 C., but, like the other organism, it can withstand short 

 .exposures to temperatures down to -191 C. ; it is quickly 



