288 



H. M. WOODCOCK. 



almost anywhere in the anterior half of the body, but is 

 usually near the extremity .^ 



The question of the sub-classification of this genus is one 

 of much difficulty. One is confronted by a great number of 

 forms, several of which have no very definite or constant 

 differential feature by which to characterise them, such as in 

 the case of the Gregarines and Coccidia, for example, is 

 naturally afforded by the spores. This is largely owing to 

 the fact that so little is yet known of the life-history of most 



ABODE 



Fig. 42. — Different Mammalian Trypanosomes to show uni- 

 formity in size and shape, a, Trypanosoma evansi; b, T. 

 brucii; c, D, T. equiperdum; E, T. equinum, x 1500. 

 (After L. and M.) 



that reliance has to be placed almost entirely upon the adult 

 size and form in any endeavour to classify the parasites on a 

 morphological basis. Now it has been already stated that, 

 in many cases, the variation in this respect is very slight, 

 and, in addition, in several instances a particular form may 



1 The type-species is T. rotatorium (Mayer) of frogs. At present, 

 unfortunately, this parasite cannot with certainty be included in the above 

 diagnosis, owing to its unusual shape, position of kinetonucleus, etc. The 

 occurrence, however, of an allied form in Hy la, which is evidentl}' inter- 

 mediate between T. rotatorium and the more typical, fusiform species 

 of the genusjstrongly points to the agreement of the former (T. rotatorium) 

 with the majority of Trypanosomes in belonging to the Heteromastigine 

 section. At any rate, it would be premature to separate the Mammalian and 

 Piscine forms under a new generic name ; the confusion which this course 

 would entail is to be avoided until it is sliown to be necessary. 



