NOTES ON JAPANESE TRICLADS. 445 



As regards the sperm atophores contained in the receptaculum 

 seminis, e.i., those which, in my opinion, had been transfered by copu- 

 lation from one individual into the receptaculum of another, I have met 

 with such on several occasions in PI. vivida. They occurred either 

 singly or two together at a time, not infrequently represented only by 

 incomplete capsules which had emptied their proper contents. It is 

 important to note that the spermatophore thus found in the recepta- 

 culum is of a shape and size well agreeing with the one described above 

 from the vesicula seminalis. 



As already indicated, the pyriform shape of the spermatophore of 

 PI. vivida apparently stands in relation with the shape of the space of 

 its origin, viz., the vesicula seminalis and the adjoining parts of vas 

 deferens impar. In this connection I may mention that in both PI. 

 burmaensis Kab. and PI. Cmnaridalei Kab. the spermatophores I have 

 found in the receptaculum were also of a shape corresponding to that 

 of the part of penis lumen known as vesicula seminalis. In the former 

 species the shape was elongate ovoid, and in the latter tubular. 



The eosinophil nature of the substance of the spermatophore capsule 

 decidedly differentiates it from the cyanophil secretion of the glandular 

 cells discharging into the receptaculum seminis. Micoletzky assumed 

 that the receptaculum secretion changes from cyanophil into eosinophil 

 during the process of the capsule formation in that organ. This he 

 based on his observation of the staining property of the receptaclum 

 fluid enclosing a spermatophore, using hsematoxylin-eosin for the stain. 

 He found in sections that the fluid coagulum in immediate contact with 

 the spermatophore capsule stained red — i.e., was eosinophil, — though in 

 more remote parts it was cyanophil, the red and blue grading over into 

 each other in the intermediate parts. A similar result I have obtained 

 with PI. vivida under the same circumstances of condition and treat- 

 ment ; however I am inclined to interpret the differential staining to be 

 due to the receptaculum fluid being in the process of dissolving up the 

 substance of the spermatophore capsule. 



