274 H. M. WOODCOCK. 



ill tlie last-named instances this structure is near the anterior, 

 flagellate extremity of the cell. If, therefore, Trypano- 

 soma sensu stricto is a Herpetomonadine form, why is 

 the vacuole, where known to occur, always near the non- 

 Hagellate, apparently opposite end of the body ? 



(1) Conversely the chromatoid grains, so frequently notice- 

 able in the cytoplasm (see above, p. 211), are, in Trypano- 

 soma/ mainly or entirely in the flagellate half of the body, 

 or, at any rate, on that side of the nucleus (figs. 16, 17, 42, 47, 

 and 57). On the other hand, in Herpetomonas gracilis, 

 which also possesses a number of similar grains, they are all 

 in the non-flagellate part of the body, that is to say, behind 

 the nucleus (fig. 58 b). Com pare the cy tological details 

 of this parasite with those of^ say, T. nelspruitense 

 (fig. 17 e), and it appears unquestionable that the 

 flagellate end of the former corresponds to the non- 

 flagellate one of the latter. Again, in Trypanomorpha, 

 pigment grains and other eifete material collect near the non- 

 flagellate (posterior) end^ and the cytoplasm near this ex- 

 tremity is frequently more granular and deeply staining (figs. 

 8, 10, and 13) than it is near the flagellate end, or just the 

 opposite to what is generally the case in Trypanosoma. 



It is surely needless to suppose the position of these two 

 cytological constituents in the body of Trypanosoma to 

 have become, for no obvious reason, absolutely reversed 

 (which one is bound to do if the Herpetomouadine view 

 be adhered to), when, on the one hand, no stage from 

 Herpetomonas to Trypanomorpha inclusive shows any 

 indication of such a change, and, on the other hand, in 

 Trypanoplasma borreli, they have exactly the same 

 position relative to the attached (posterior) flagel- 

 lum that they have in Trypanosoma (cf. fig. 17 f and g, 

 and especially Laveran and Mesnil's amended 1^'ig. LVI, 5, 

 [56], in which the chromatoid grains are entirely behind the 

 nucleus). Granted the loss of the anterior flagellum, and we 



' In T. granulosum (fig. 17k) they are uuifoiiuly distributed through- 

 out the cytoplasm, but this is, apparently, the only exception. 



