714 Jl. M. WOODCOCK. 



have been described by Roubaud (26). In the case of the 

 first-named, tlie indiv^iduals figured certainly appear to be 

 in a definite trypaniform condition, possessing a distinct, 

 though narrow, undulating membrane. The two other para- 

 sites are very remarkable, in that typical herpetomonad 

 forms appear to have also a " trypanosome " phase in their 

 life-cycle, and all intermediate conditions between these two 

 extremes are figured. So far as I can judge from the figures 

 given, however, the so-called " trypanosome" phases do not 

 represent a true trypaniform condition in the sense in which 

 it has been understood in the above pages. To begin with, 

 the flagellar end of the body is not drawn out at all, but the 

 flagellum emerges straightway from it. The kinetonucleus 

 is, indeed, near the aflagellar end of the body ; but in all 

 cases the course of the flagellum, from the point where it 

 comes into contact with the cytoplasm up to the kineto- 

 nucleus, is shown i-unning: throusrh the middle of the cvto- 

 plasm ; it is never drawn lying at the side, still less as showing 

 any undulations. I think this is an important point, and one 

 which tells very much against the presence of an undulating 

 membrane in these Leptomonas. For in the great majority 

 of preparations of trypaniform parasites, however attenuated 

 they may be, and however narrow the membi*ane, the attached 

 flagellum lies nevertheless at one side (cf . my figs. 10, 126-132, 

 and also Minchin's figures of T. grayi). I think, therefore, 

 that in these peculiar phases a considerable part of the 

 flagellum is intra-cytoplasmic, forming, as it were, a long 

 rhizoplast, consequent on the passage of the kinetonucleus to 

 the opposite end of the body. These forms appear to be 

 quite distinct both from ordinary herpetomonad parasites 

 and from the true trypaniform type. f'X" drosophilse, 

 on the other hand, appears to exemplify the trypaniform 

 condition. 



The above summary represents, in my opinion, the present 

 position of this difficult problem of the flagellates occurring 

 in blood-sucking invertebrate hosts. My view on the subject 



