554 



TRYPANOSOMES AND TRYPANOSOMIASES 



the nucleus proper, the tropho- or the macronucleus; the other one, 

 quite small and dot-like, is known as the micronucleus, 1 or, more 

 properly, the centrosome, or blepharoblast, and it is generally found 

 at the posterior end of the microorganism. From the centrosome 

 starts a thin, folded membrane, the undulating membrane, it has a 

 thickened border which runs out into a free whip-like filament called 

 the flagellum. The latter is composed of three parts, the root which 



FIG. 188 



Anterior extremity 



Large protoplasmic 

 granules 



Nucleus 



Centrosome 

 Posterior extremity 



Flagellum, third 

 part; free end 



Flagellum .second 

 part 



Undulat. membrane 



i Flagellum, first part 



Morphology of Trypanosoma Brucei (schematic). 



arises from the blepharoblast and extends in the protoplasmic body as 

 far as the undulating membrane, the second portion which runs along 

 the free border of the latter, and the third portion which is the 

 filamentous free end. The undulating membrane and the flagellum 

 form the organs of locomotion of the trypanosome, and they enable 



1 Calkins says: "The terms macronucleus and micronucleus are frequently used to designate 

 the trophonuclei and kinetonuclei of these flagellates (trypanosomes), but this use of the 

 term micronucleus is greatly to be deplored, since the kinetonucleus has absolutely no analogy 

 with the micronucleus of infusoria, and the binucleate condition of the trypanosomes is to be 

 explained upon other grounds than that of the ciliates." 



