26 H. M. WOODCOCK. 



tlie plaue of junction, which would be the case were it a tiue 

 ectoplasm (cf. D. schneideri). 



Loss of the power of movement. — Even less is there 

 anytliing- corresponding to a laj'er of myoc3^te fibrilku to be 

 noticed in Cystobia^; and the same appears to be equally 

 true of Diplocystis. The loss of mobility which is exhibited 

 by these coelomic parasites is undoubtedly correlated with 

 their more confined situation, since they tend to remain in 

 close relation with their host's tissue, instead of early becoming 

 "free" in the lumen of the gut, as is the case Avith most 

 motile Grregarines (compare, e.g., C. minchinii and a 

 Coccidian). 



Consideration of '^ Diplocystis schneideri." — 

 After careful examination, I have to differ in many points 

 from Kunstler's interpretation of the structure of the peri- 

 pheral region and the nature of the septum in this parasite." 

 In fig. 27 1 have drawn on a large scale a small portion of 

 the peripheral region of two syzygies, showing the com- 

 mencement of the plane of junction in each. Passing from 

 without inwards, there is first a general investing membrane 

 {i.m.) secreted by the parasite. If this represented a serous 

 sac, it would certainly show nuclei or other traces of cellular 

 structure, of which, however, there is not the least sign. It 



' The fact that this lack of muscle-fibrils is accompanied by a complete 

 absence of mobility in these Giegarincs is a strong confirmalion of Crawley's 

 theory (9), that, " in general, throughout the Sporozoa, the possession of 

 muscle-fibres and the power of moving from place to place go liand in hand, 

 wliile those forms which are not known to move lack muscular elements," 

 which thus attributes actual progression to the myocyte fibrillse ralher llian to 

 the extrusion of gelatinous threads posteriorly. 



"^ Kunstler (loc. cit.) regarded the common or investing membrane as 

 consisting of two layers, the outer being derived from the host, the inner 

 corresponding to a cuticle or limiting membrane. Internal to this came (he 

 ordinary ectoplasm, which alone (in his opinion) formed the partition between 

 the two "halves." For Kunstler considered liiat each couple represented a 

 single individual ia process of division, the septum being a transverse continu- 

 ation, through the cudo])lasm, of the peri})hcral cctoplasu). There can be little 

 doubt that this interpretation was entirely erroneous. 



