STRUCTURE OF THE FEMALE ORGANS. 441 



musculature, the generative cloaca is able to undergo manifold 

 changes in form and width, and thus to narrow or widen its opening. 

 These changes occur mainly in consequence of the pressure and trac- 

 tion of the adjacent body muscles. 



We can the more rapidly dismiss the muscular structure of the 

 cirrhus-pouch, since it was especially Tcenia sayinata which we had 

 in view in our general account of this organ (p. 310). 



The peripheral layer which the pouch possesses leads one to sup- 

 pose that it is in the cortical layer that the cirrhus-pouch has arisen. 

 This cannot indeed be demonstrated with certainty, since the above- 

 mentioned course of the transverse fibres obliterates the boundaries 

 between the two layers of the body. The nerve cord and the longi- 

 tudinal vessel, which are both distinctive of these layers, lie internally 

 to the cirrhus-pouch, but are divergent, inasmuch as they are not close 

 beside each other, but are approximated to different surfaces of the 

 body the longitudinal vessel towards that which we have formerly 

 called the "female," and the nerve cord towards the opposite or 

 "male" surface. The cirrhus-pouch is also more or less distinctly ap- 

 proximated to the latter, whether the pore be on the right or left side 

 of the body. 



Although the situation of this pore varies extremely, lying always 

 on one side for perhaps six or eight joints, and then alternating 

 almost regularly throughout another series, yet there is on the whole 

 but little difference in this respect between the two sides. In a 

 length of 100 joints I counted 56 pores on the left, and 44 on the right. 



Whether the pore lie right or left, one always finds it at some 

 distance behind the middle, and that the more markedly the longer 

 the joint. In isolated proglottides 12 mm. long, it lies fully 7 mm., 

 and sometimes even more, behind the anterior border. 



The Female Organs. The narrow funnel-like end of the generative 

 cloaca contains not only the male opening with the copulatory organ, 

 but also, as we have seen, the female opening. This is so closely 

 approximated to the former, that the cirrhus can easily bend round 

 into it when the pore is closed. I have seen this take place in Tcenia 

 echinococcus and other species from the dog, and therefore I presume 

 it happens also in T. saginata. 1 The semen, thus introduced into 

 the female organs, first passes through the slightly enlarged terminal 

 portion into the vagina. This is a long and thin (0'025 mm.) canal, 

 which pursues for a while a straight course below the coiled vas 



1 I have already (p. 310, note) mentioned that Somraer denies the entrance of the 

 cirrhus into the vagina, and asserts that the semen simply overflows into the female 

 opening without any true copulation. He thinks that I have been misled in my 

 observations by a stream of spermatozoa. 



