1914] A New Cestode from A mi a Calva L. ioi 



processes from parenchymatous cells lying farther out. The circular 

 muscles increase in number at the opening of the cirrus and form a dis- 

 tinct sphincter. In that portion of the cuticle next the lumen, that is, 

 towards the functional outer surface of the organ, there are to be seen 

 numerous highly-staining granules which seem to be the bases of fine 

 bristle-like processes extending into the lumen. While the granules 

 show very plainly in sections, the processes themselves are difficult to 

 make out clearly in many cases. They are, however, probably homo- 

 logous with the spines, hooks, etc., described for the cirri of other species. 

 Fig. 25 shows a somewhat younger stage in the development of the 

 cirrus than that shown in Fig. 24, and is of interest in connection with 

 the problem of the formation of the cuticle. Considerable attention was 

 paid to detail in this figure in order to bring out the following points. 

 It will be seen that four or five nuclei lie close to the cuticle, in fact 

 against the basement-membrane, while others farther out appear to be 

 connected with the cuticle, or at least with the syncitium of protoplasm 

 immediately outside of it, by fine strands. Many of these peripherally 

 situated nuclei belong to the myoblasts of the circular muscle-fibres, as 

 indicated by the letters "cmc", and some of them to the few longitudinal 

 fibres, but they, especially the former, are fairly easy to distinguish from 

 the majority of the number which have the central protoplasmic connec- 

 tions. Young ('13) and Schaefer ('13), working with different species 

 of cestodes, came to quite opposite conclusions regarding the fate of the 

 epithelial nuclei during the formation of the cuticle in the distal portions 

 of the vas deferens and of the vagina. Young asserts that the nuclei 

 disintegrate in situ as the cuticle is being formed, while Schaefer ob- 

 served what is doubtless the migration of the nuclei into the surrounding 

 cytoplasm. The writer does not pretend to have gone into the matter 

 at all exhaustively, but from the few observations he has made on the 

 material studied it would appear that this species falls into line with 

 Schaefer's discoveries. At any rate, no conclusive evidence of nuclei 

 having disintegrated in situ in either the cuticle of the cirrus or that of the 

 vagina was met with, but appearances like that shown in Fig. 25, where 

 the original syncitial nuclei seem to have migrated some distance from 

 the developing cuticle, retaining their protoplasmic connections and 

 possibly functioning in the formation of that layer by secretion, are very 

 common. In later stages, evidently when the cuticle is completely 

 formed, these connecting strands fuse with the general mass of paren- 

 chymatous cytoplasm surrounding the cirrus and its retractor muscles, 

 giving the appearances shown in Fig. 24. More will be given below in 

 this connection under the vagina which, on account of its comparatively 

 greater length, is better adapted to show the stages in the development 

 of the cuticle. 



