104 Transactions of the Royal Canadian Institute, [vol. x. 



by Schaefer the process takes place, in all probability, quite rapidly, 

 thus rendering the finding of the nuclei in all of the stages a matter of 

 some difficulty in a comparatively small number of series. Three figures 

 are given, however, to illustrate what was observed by the writer in this 

 connection. Fig. 39 is a photograph of a coronal section through the 

 first portion of the vagina, the entrance to the vagina being shown at 

 "v". The latter is seen to be surrounded by a number of radiating 

 cylindrical cells with rounded peripheral ends towards the parenchyma, 

 somewhat resembling the cells of the subcuticular layer. They are much 

 more numerous around the enlarged portion of the vagina than around 

 the duct farther back. At "x" one of these elongated cells, with the 

 nucleus situated at its extremity, is attached to the cuticle tangentially 

 and in such an intimate manner as to lead one to think that it still 

 functions, possibly, in the formation of the latter. Again at "x" and 

 "y". Fig. 40, two nuclei with the surrounding cytoplasm appear to have 

 passed through the basement-membrane but to have gone only a short 

 distance beyond it. A similar case is shown in Fig. 41 at "y", while at 

 at the point marked "x" a nucleus half way through the basement- 

 membrane is to be seen. As the nuclei pass through the latter they are 

 surrounded in many cases by clear areas, possibly cytoplasm quite thin 

 in consistency, as noted by Schaefer in Bothridium pithonis Blain. 

 Thus it appears — to the writer, at least — that, in the transforma- 

 tion of the epithelium of the distal portions of the vagina and vas deferens 

 into the cuticle, the nuclei of the former pass into the surrounding 

 parenchymatous tissue, and may there function in the formation of the 

 latter. While the above evidence is scarcely to be considered as con- 

 clusive, it is given in the hopes that it will be at least suggestive to the 

 reader in connection with the question of the formation of the cuticle 

 in cestodes, which is again occupying the attention of helminthologists. 



The musculature of the vagina is composed of circular fibers only, as 

 in Cyaihocephalus truncatus (Pallas), which are situated immediately 

 outside of the basement-membrane. Very few of them surround 

 the greater part of the canal, including its anterior enlargement, 

 but a comparatively large number are developed in the short region 

 between the latter and the opening to form a powerful sphincter, 30 to 

 40 IX in length. 



From a point opposite the posterior end of the uterus-sac and ventral 

 to the uterine tube (" Uteringang ") the vagina gradually enlarges as it 

 passes dorsally over the ovarian isthmus to form the receptaculum 

 s e ra i n i s . The posterior, rounded end of the latter is situated within 

 the generative space dorsal to the oocapt, with its longitudinal axis almost 

 vertical (Fig. 27). The diameter of the tube at this point varies from 



