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generally easily appreciable, at least in the blood, but as 

 we shall see later, such forms have also been described 

 in the gut of flies transmitting particular trypano- 

 somes, and the differences are there said to be well 

 marked. In the case of T. brucei, for example, three 

 types are described in the blood. 



(1) Male Forms. Excessively slender forms 

 staining deep blue, with a sharply defined, rather long 

 chromatin-rich nucleus. They are more actively 

 motile than other forms. 



(2) Female Forms. Flagellum short. Membrane 

 slender, little folded ; two or three times as broad 

 as other forms. They stain a light blue ; have few 

 or no granules and the nucleus is spherical. 



(3) Indifferent Forms. The most numerous form. 

 The nucleus is not sharply defined, and the protoplasm 

 contains numerous granules. 



It must, however, be remembered that all transi- 

 tions appear to occur between these forms, and that 

 observers are by no means agreed as to which of these 

 forms are which ; and finally it must be noted that the 

 amount of granules and the depth of staining of the 

 protoplasm of a trypanosome can be made to change 

 at will by varying the composition of the Romanowsky 

 and by washing for variable lengths of time. 



Mode of Division. This is by longitudinal division. 

 The trypanosome at the time of division increases 

 considerably in thickness. The nucleus and blepharo- 

 plast divide, sometimes one first, sometimes the 

 other. A new flagellum is formed by an out-growth 

 from the new blepharoplast ; or according to others 

 by a splitting of the base of the old flagellum. Finally 

 the protoplasm also, divides. For rosette formation 

 vide under T. lewisi. 



Encysted Forms. In animals treated with atoxyl 



