MASTIGOPHORA 389 



diversity of form is observed in the trypanosomes within the fly but 

 the significance of the different types is not yet fully understood. 



Many of the mammals are susceptible to inoculation with 

 Tr. gambiense. White rats usually relapse 2 or 3 times before 

 finally succumbing to the infection, whereas they usually die 

 within 2 weeks when inoculated with Tr. brucei. The virulence 

 of the organism is somewhat variable. 



Attempts to cultivate Tr. gambiense in artificial media have 

 not been fully successful. It has been possible to obtain multipli- 



FIG. 157. Glossina palpalis in natural resting position, and with wings outstretched. 



(After Dofiein.} 



cation of the organisms and to keep them alive for several weeks 

 on blood-agar but such cultures'are not virulent and cannot be 

 kept up indefinitely. 1 



Human trypanosomiasis is a most important and widespread 

 disease in equatorial Africa. Symptoms appear long after the 

 infection has taken place. The disease manifests itself in two 

 forms, the trypanosoma fever and the sleeping sickness. Trypano- 

 soma fever is an irregularly remittent fever lasting for several days 

 at each attack, accompanied by a macular eruption, and always 



1 Thomson and Sinton: Annals of Trop. Med. and ParasitoL, 1912, Vol. VI, 

 PP- 331-356. 



