TRYPANOSOMIASIS. 671 



the cell body is continuous with an "undulating 

 membrane/' which extends along a border of the 

 organism to a point near the centrosome or mi- 

 cronucleus in the posterior portion of the cell. 

 The centrosome is sometimes spoken of as anala- 

 gous to the "eye spot" of some other protozoa. The 

 undulating membrane is more or less wavy or 

 folded and its breadth varies. The centrosome pre- 

 sumably has a close relationship to the undulating 

 membrane, and, through the latter, with the flagel- 

 lum. The nucleus is in the anterior portion of 

 the parasite. In relation to some species a con- 

 tractile vacuole is spoken of. An endoplasm and 

 an ectoplasm may be differentiated. 



Division of trypanosomes is nearly always longi- 

 tudinal, rarely transverse. In the process of longi- 

 tudinal fission the order of division of the differ- 

 ent parts of the cell is as follows : 1, Centrosome ; 

 2, flagellum; 3, nucleus and protoplasm (Laveran 

 and Mesnil). After division has occurred the two 

 cells may remain attached at their posterior ends 

 for some time. By a repeated division of young 

 cells, the posterior ends remaining attached, ros- 

 ettes are said to be formed. Others consider ros- 

 ette formation as a phenomenon of agglutination. 

 Possibly both phenomena occur. 



Koch and others have described sexual repro- 

 duction in the tsetse-fly. 



Koch divides the trypanosomes into two classes classification. 

 as to constancy in respect to : ( 1 ) morphology ; 

 (2) virulence; (3) host. This classification is 

 best represented by the accompanying table from 

 Nocht and Mayer. 



