804 



THE FLAGELLATA 



The parasites are [in the majority of cases] transmitted by the bites of 

 blood-sucking insects in which the Trypanosomes multiply by sexual repro- 

 duction (sporogony) and of which the details are still imperfectly known 

 [but see T. equiperdum and T. equinum.] 



FIG. 387. The Trypanosomidce. (After Guiart.) A, Trypanusumu , 

 C, Herpetomonas ; D, Spirochceta ; E, Treponema. 



B, Trypanoplasma ; 



Schaudinn distinguished several genera of the Trypanosomidse. 



1. The genus Trypanosoma : having an undulating membrane and one flagellum. 



2. The genus Trypanoplasma : having in addition to an undulating membrane 

 and an anterior flagellum, a second free flagellum inserted into the posterior part 

 of the body. 



3. The genus Herpetomonas : having a free flagellum but no undulating membrane 

 (p. 805). 



4. The genus Spirochaeta : elongated, sinuous organisms having an undulating 

 membrane, but no flagellum. 



5. The genus Treponema : elongated, sinuous organisms having a short flagellum 

 at each end but no undulatory membrane. 



It has already been pointed out that this classification is not universally accepted 

 and that by some observers the spirochsetes and treponemes are grouped with the 

 bacteria (p. 711). 



Methods of examination. In searching for trypanosomes fresh blood 

 should be examined in the same way as for the haematozoa (p. 771). For 

 prolonged observation, such as the study of agglutination, hanging drop 

 preparations (p. 132) luted with vaseline or paraffin are necessary. To 

 prevent coagulation the blood should be mixed with citrated normal saline 

 solution : 



Water, - - - 1000 grams. 



Sodium citrate, - 6 



Sodium chloride, 6 



The citrated blood may also be defibrinated. Or the blood may be allowed 

 to coagulate ; the trypanosomes then pass into the serum and can be studied 

 unhampered by the red cells (Francis). 



For stained preparations, the best method is that of Laveran, using BorreFs 

 blue (p. 772). In the case of most of the Trypanosomes found in the mam- 

 malia it is sufficient to stain for 5 or 10 minutes, but in the case of Trypano- 

 soma lewisi the staining must be continued for 20 minutes (p. 806 fig. 388 

 appearances produced by staining). 



Any of the methods described as useful for the Hcematozoa are applicable 

 to the staining of the Trypanosomata. One of the best stains is Laveran's 



