PROTOMONADIDA 



137 



Near the bluntly rounded end, there is a blepharoplast and 

 usually a basal granule from which the flagellum arises and 

 runs toward the other end, marking the outer margin of the 

 undulating membrane. In most cases the flagellum extends 



Fig. 48 The life cycle of Trypanosoma melophagium in the blood of sheep and 

 in Melophagus ovinus. (After Hoare). 

 a, trypanosome as ingested by Melophagus with the sheep's blood; b-e, 

 crithidia formation through division; f-h, large transitional crithidia in the 

 hind-gut which by division are transformed into smaller forms; i-k, formation 

 of metacyclic trypanosomes; 1-m, formation of pyriform crithidia; n, leish- 

 mania forms. 



freely beyond the body. Myonemes are common. Asexual re- 

 production is binary or rarely multiple fission. The organism 

 is carried from host to host by blood-sucking invertebrates 

 and undergoes definite changes in the alimentary canal of the 

 latter (Fig. 48). Sexual reproduction is not known. A number 

 of forms are pathogenic to their hosts and the diseased condi- 

 tion is termed trypanosomiasis in general. 



