lo Maurice Croivthcr Hall 



muscular coating." He notes that the muscular sheet "between 

 the cuticle and cortical parenchym is inflected to constitute the 

 transverse partition"; Lankester (1872), as previously noted, re- 

 garded the cortex as the seat of muscular activity ; Biitschli 

 (1882) regarded the ectoplasm as contractile and the myocyte 

 as doubtfully so. 



The common view of the myocyte is that stated by Crawley 

 (1905), "a layer of fibrils," and contrary to the position in which 

 it was found by v. Beneden (1872), it usually occurs on the bor- 

 der between the ectocyte and entocyte. In mounts of young 

 specimens of Hirmocystis rigida I find between the sarcocyte and 

 entocyte the row of dots which is classic as indicative of the myo- 

 cyte fibrils in cross-section, but in mature specimens the myocyte 

 appears to be represented by the fibers in the sarcocyte. while the 

 border between the sarcocyte and entocyte has a structure which 

 I have not seen specifically described elsewhere. This structure 

 (fig. 2) shows near the septum in longitudinal sections as a row 

 of dots or short lines in the protomerite and deutomerite, merg- 

 ing into a solid line, which forms the septum. In very young 

 specimens the ectocyte, as such, seems to form the septum, wdiich 

 may take any position between the presentation of a strongly 

 convex surface to the protomerite, and the reverse of this. Biit- 

 schli (1882) has noted that the septum may form from the cuticle 

 itself in young gregarines. and this may be the case here. He 

 also records v. Beneden's statement that in forms without a sar- 

 cocyte the cuticle may form the septum permanently. It is com- 

 monly held that the sarcocyte forms the septum and it is probable 

 that here the inner sheet limiting the sarcocyte and occupying 

 the usual position of the myocyte is merely a sarcocyte differen- 

 tiation. It is also held, as Wasielewski (1896) states, that the 

 myocyte "fehlt in Niveau des Septems," but in the gregarine 

 from Mclanopliis I am inclined to regard the septum as of a con- 

 tractile nature, since mere peripheral constrictions of the fibrous 

 sarcocyte seem inadequate for the production of the elaborate 

 symmetrical folding over a circular surface necessary to account 

 for the forms shown (figs. 16-20). Still the explanation of this 



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