THE SHELL AND GERM GLANDS. 



443 



It communicates further not only with the fertilising canal, but 

 also with the germarium and with the uterus, so that it is anatomically 

 a sort of centre of the female reproductive system. 



r.s. y- 9. 



Fig. 250. — Sexual organs of T(snia aaginata (x 10). Male organs. — 

 U, testes; v.d., vas deferens; c.p., oirrhus-pouch. Temale organs. — ov., 

 ovary ; y.g., yolk-gland ; m.h., shell-gland (Mehlis' body) ; r.s,, receptaculum 

 seminis; ut., uterus ; v., vagina ; g.p., genital papilla ; cl., cloaca. 



The Germ-Glands consist, as usual iu the Tseniadse, of a paired ovary 

 and an unpaired yolk-gland. The latter, the "albumen-gland"^ of 

 Sommer, lies below the spherical body just described, near the posterior 

 border of the joint, and is in the form of a triangle, which has its obtuse 

 angle turned forwards, and extends some distance towards either side. 

 Sometimes the inferior margin is hollowed out or even inteiTupted, so 

 that it then appears almost double, as is shown in Fig. 142, represent- 

 ing Taenia solium. But such appearances are neither normal nor yet 

 individual variations, as I was formerly inclined to suppose,^ but are 

 artificially produced by unequal compression. 



In contrast to the yolk-gland, the ovary has the form of two large 

 and almost round wing-like organs. They lie at either side of the 

 receptaculum seminis, but above the shell gland, and occupying more 

 than half the breadth of the remaining space (Fig. 250). Their height 

 is about the third part of the length of the joint. The space between 



■ We have already (p. 320) given reasons for regarding this so-called "albumen- 

 gland " not as an organ occurring only in the Tseniadse, but as a form of yolk-gland widely 

 distributed among the Platyhelminthes. 



'' I must again note (see p. 315, note) that in the first edition of this work I 

 erroneously regarded the yolk-gland as the ovary, and vice versa, as has been rightly 

 pointed out by Sommer. 



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