82 H. M. WOODCOCK. 



degree of parasitism attained. Brasil (loc. cit.) admits this 

 influence upon their trophic organisation, but thinks, appa- 

 rently, that the exact nature of the reproductive process is 

 uninfluenced by this feature. I do not think this view can 

 be maintained. If not directlj^, the influence can certainly 

 be traced indirectly. There is abundant evidence that modi- 

 fications in trophic life themselves influence the mode of 

 reproduction ; examples of this have been numerous in the 

 preceding pages. Hence for this reason alone we ought to 

 be very cautious in assuming that the manner of reproduction 

 of these coelomic Gregarines is primitive. Lastly, when we 

 remember that the Flagellate origin of the Gregarines is 

 almost certain, it seems most natural to regard a condition 

 where we have motile anisogametes as being more primi- 

 tive than the one we find in the Monocystids, which has most 

 likely resulted in the way I have described above. 



Tabular comparison. — It may be useful to summarise, 

 in tabular form, the principal stages in this line of develop- 

 ment, as illustrated by known forms. Schaudinnella itself 

 is best left aside. This is, undoubtedly, a very exceptional 

 parasite, primitive in some respects (e.g. in the character of 

 its association), but specialised in others. As Brasil says, it 

 cannot be very well compared with any known Gregarine. 

 In my opinion it represents a primitive Telosporidian parasite 

 which has endeavoured, as it were, to go in more than one 

 direction at once, combining, to a certain extent, both 

 Gregrarine and Coccidian features. 



(a) Intestinal forms. 



(1) The gametes are highly differentiated. Example : 

 P t e r o c e p h a 1 u s . 



(2) The conjugating elements, though readily distinguish- 

 able into male and female, are not so markedly differentiated : 

 certain very motile and spermatozoon-like nuile ones are 

 sterile, and have acquired a subsidiary function. Example : 

 S t y 1 o r h y n c h u s . 



