450 



WINTERTON C. CURTIS, 



vesicle, with greatly reduced diameter, is prolonged forward as the 

 vas deferens and terminates in the testicular canal of the most an- 

 terior testis, with the other follicles opening into the duct along its 

 length as is shown on (PL 31, Figs. 1 and 8). In Planaria montana, 

 however, the testes are restricted to a region between the ovaries and 

 the insertion of the pharynx and are much more numerous. Chich- 

 KOFF ('92, p. 521) shows that there are two modes of com- 

 munication between the testes and vasa defer entia in the fresh water 

 as in the land forms (Bipalium, Moseley, '74, and Geodesmus, Ken- 

 nel, '79), first by a direct opening, and second by a short canal and 

 that the two are not essentially different the canal being found where 

 the follicles are somewhat removed from the vas deferens. In fact 

 they are sometimes found side by side in the same animal (PI mon- 

 tana and Planaria lactea Chichkoff, '92). 



In Planaria simplissima the communication is effected by the elon- 

 gated canals alone and it is possible (PI. 31, Fig. 7) to trace the course 

 of a downward prolongation from the wall of each follicle connecting it 

 with the vas deferens. The testis, lying in the parenchyma a short distance 

 below the dorsal surface of the body (PI. 32, Fig. 10), has its epithehal wall 

 of sperm-mother cells (e^j) drawn out on the lower side and continued 

 into a canal (tc) which in longitudinal section often shows its lumen 

 cut open. This canal passes between the gut-lobes and communicates 

 with the vas deferens (vd) after the manner shown. The entire length 

 of a canal is not often found in a single section as in the figure just 

 quoted, but can be traced in serial sections. While this is the ar- 

 rangement most frequently met with, not uncommonly the outlet is 

 effected through a neighboring follicle (PI. 31, Fig. 2 fe 3, and PI. 32, 

 Fig. 13 te 3). I have seen only one case, however, where there was 

 a double connection of any sort (PI. 32, Fig. 13 ^e ^ and te 2). 



These testicular canals or vasa efferentia were found in a large 

 majority of the follicles examined. They are difficult to follow unless 

 cut longitudinally and as the angle at which they enter the vas de- 

 ferens varies greatly no possible plane will cut all in longitudinal 

 section. PI. 31, Fig. 7, represents a remarkable case where parts 

 of four out of the five testicular canals of one side appeared in a 

 single section. The fifth follicle, however, was some distance removed 

 from the vas deferens and its duct only made out after a careful 

 search. It is shown by the dotted outline in Fig. 7, while in Fig. 8, 

 just below, the testes, testicular canals, and vas deferens are seen as 

 reconstructed from the sections of this series. I have repeatedly 



