Japanese Tricladida Maricola. 35 



As at first described by Stoppenbrink (57), three portions 

 can generally be distinguished in the oviduct, viz., a foremost 

 swollen portion designated by the name of the tuba, a middle 

 portion receiving the vitelline glands at numerous points and a 

 hindmost portion. 



As is well known, the oviduct uf each side starts from the 

 postero-lateral aspect of the ovary as an ampuUaceous passage 

 filled with spermatozoa. There exists no direct communication on 

 the boundary l:)etween the oviduct and the tuba, where "Schluss- 

 platte" in the sense of Böhmig is formed. It always presents 

 a well defined lumen and is, as in most species, lined with an 

 epithelium of cylindrical cells, each of which shows at the base an 

 ovoid nucleus. Internally the epithelium is seen to be uniforml}^ 

 covered with cilia. A large number of spermatozoa completeh^ 

 fill up its lumen. So far as my observations go, however, no 

 trace of spermatozoa could aiiyv/here be detected in the ovary. 



The occurrence of sperm-masses in the tuba has convinced 

 me that the spermatozoa introduced l^y the act of copulation from 

 one individual into the receptaculnm of another may perhaps lie 

 enticed by a certain chemotactic stimulus into the tuba, after leav- 

 ing the receptaculnm. As mentioned b}^ Stoppenbrink, Mico- 

 LETZKY, Burr and others, the tuba appears to function as a kind 

 of the receptaculnm. It is beyond doubt within the lumen of the 

 tuba that fertilization takes place. 



The tuba soon assumes the character of a narrow tube, wliich 

 stands in connexion with the vitelline glands at many points 

 through the whole length. The mode of their connexion presents 

 no difïerence from that observed by Böhmig, and the vitelhne 

 glands are connected by means of a short funnel-like stalk with 

 the oviduct. 



In Pr. lactea the oviducts open behind the vagina into a 

 common root, like in Pr. lobata, which presents the appearance of 

 a small outbulging of the vagina, Ijeing directly marked by 

 numerous eosinophil glands. In St. trlyonocephala, although in 

 some cases a tendency to such outbulging is observable, they 

 .generally open separately into the vagina, and are lined l)y an in- 



