274 



PROTOZOOLOGY 



No other stages are found in the human host. When a "tse-tse" 

 fly, Glossina palpalis or G. tachinoides, sucks the blood of an in- 

 fected person, the trypanosomes remain in its stomach for a few 



Fig. 120. The Hfe-cycle of Trypanosoma lewisi in the flea, Ceratophyl- 

 lus fasciatus (Minchin and Thomson, modified), a, trypanosome from 

 rat's blood; b, individual after being in flea's stomach for a few hours; 

 c-1, stages in intracellular schizogony in stomach epithelium; m-r, two 

 ways in which rectal phase may arise from stomach forms in rectum; 

 s, rectal phase, showing various types; t, secondary infection of pylorus of 

 hind-gut, showing forms similar to those of rectum. 



