TAENIA 



173 



gether into larger and larger channels, terminating eventually at the 

 inner end of a main transversely-running vas deferens (v.d), which func- 

 tions as a seminal vesicle for storing the spermatozoa and opens into a 

 crater-like recess, common to it and the female opening, and situated at 

 the apex of a small projection, or papilla, at the margin of the proglottis. 

 In successive proglottides the genital papillae are quite irregularly on one 

 side or the other. As in the case of the fluke the terminal portion of the 

 male duct is muscular and can be protruded. 



The female portion of the gonad consists (i) of an ovary (Fig. 79, 

 A, o) of a somewhat dumb-bell shape, arranged transversely across the 



FIG. 79- 



Illustrating the arrangement of the genital organs in a sexually mature proglottis of A, Tacnia 

 and B, Bothrioccphalns. ex, excretory canal ; n, nerve-cord ; o, ovary ; od, oviduct ; s.g, shell- 

 gland ; t, testes ; U, uteras ; v, vagina ; v.d, vas deferens ; y.d, yolk-duct ; y.g, yolk -glands. (In 

 B for the sake of clearness the testes are omitted in the right half of the figure and the yolk-ducts 

 in the left half.) 



proglottis in its posterior half, the swollen ends projecting into numerous 

 little tags, and (2) a lobed yolk-gland (y.g), also situated transversely 

 but nearer to the posterior boundary of the proglottis. From the middle 

 of the ovary there slants backwards the oviduct (od) which joins the yolk- 

 duct. From the latter in turn there passes forwards^ along the middle 

 line of the proglottis, a long blindly-ending pocket, the uterus (U). 

 Surrounding the junction of uterus and yolk-duct is a rounded shell- 

 gland (s.g). The main female duct, formed by the union of yolk- 

 duct and oviduct, slants forwards and eventually runs transversely, 

 parallel to the seminal vesicle, towards the external opening as the 

 vagina (v). 



