408 MANUAL OF BACTERIOLOGY. 



but these are as yet of subsidiary importance compared with 

 those just named. 



Trypanosomes.* The trypanosomes are roughly spindle- 

 shaped and approximately crescentic. Each cell has a sharp 

 posterior extremity; the anterior extremity narrows into a 

 single long flagellum which is in active motion during life. 

 An undulating membrane surrounds the organism from 

 near the posterior extremity to the base of the flagellum. 

 This membrane can be seen with the microscope extending 

 like a fin on either side. The undulating membrane probably 

 constitutes the organ of locomotion; not the flagellum as in 

 the bacteria; since in one species the flagellum is rudimentary 

 or lacking and still the organism is endowed with the power 

 of locomotion, and, moreover, in cultures in which the undulat- 

 ing membrane is poorly developed, but in which the flagellum 

 is very long it may show scarcely any motion. The cells consist 

 of nearly colorless, almost homogeneous protoplasm. When 

 stained by the Romanowsky method various structures are 

 brought out. The nucleus which is near the anterior end 

 stains blue. The flagellum stains deep red. A body known 

 as the micro-nucleus or centrosome or blepharoplast which is a 

 prominent object near the posterior end, and which is con- 

 nected with the flagellum by a distinct line passing in the 

 undulating membrane along the side of the organism, in fact 

 it is continued into the flagellum, is also stained deep red. 

 The periblast may also take a red stain. The plasma stains 

 blue. 



The adult cell is 25 mikrons long by 1.5 wide, about 3.5 

 times as long and about one-fifth as wide as a red blood- 

 corpuscle. Multiplication takes place by obliquely longitu- 

 dinal division only. Transverse division has never been 



^Following descriptions of trypanosomes is adapted from Novy. LOG. cit. 

 For very full account of trypanosomes previous to 1903, see Musgrave and 

 Clegg. Bureau of Gov. Labs., Philippine Islands, No. 5. 1903. 248 pages. 



