362 BENEDICT. [Vol. XVI. 



very closely joined to the walls of the inner tube, and it seems 

 probable that it does not move through the tube at all. 



Kraemer's description is widely different. His drawing shows 

 a slender tube with hooks, representing the cirrus, and followed 

 by a proglottis-like arrangement, and then several coils of the 

 vas deferens within the pouch. The drawing has an unreal 

 appearance on the first glance. The cirrus, with its curved 

 hooks, is imbedded in the tissue, which must be torn through 

 before it could be protruded. The proglottis-like appearance 

 of a portion of the cirrus, as he drew it, was undoubtedly due 

 to the way in which the circular muscles were cut in sectioning 

 (PI. XVI, Fig. 31, m.s^. He drew the cavity of the cirrus, 

 into which the cut ends of the circular muscles projected, as 

 the external outline of the cirrus. The coils would be neces- 

 sary, according to his theory, but are not to be found. He 

 says that the muscles, which he calls " the roots," are for 

 retracting the pouch, which is sometimes thrust outwards for 

 some distance through the opening. This protrusion is really 

 due to an evagination of the free distal end of the inner tube. 



When the cirrus is entirely protruded it extends a length of 

 .10 mm. from the male opening. The distal end is the muscu- 

 lar knob at the end of the free part of the cirrus, which is 

 .035 mm. long. At the proximal end this free cirrus enters a 

 muscular protuberance of the shape of a truncated cone, whose 

 exterior is covered by minute, bristle-like structures. The 

 cirrus passes through the center of this and back through the 

 pouch in very intimate connection with the walls of the inner 

 tube of the sac. The mechanism of the protrusion seems to 

 be as follows : The longitudinal muscles of the cirrus sac, which 

 are reflected at the distal end of the pouch into the wall of the 

 inner tube, by contraction, would evaginate that distal portion 

 of the tube which is free from the cirrus, and pull the rest of 

 the inner tube outward through the sac, stretching the "roots " 

 (PI. XVI, Fig. 32). Because of the close connection between 

 the walls of the cirrus and those of the inner tube, the latter 

 would carry out with it the cirrus (Fig. 32). The evaginated 

 distal portion of the tube forms the muscular protuberance, the 

 former rough cuticular lining: of which is now on the outside. 



