694 . THE ANATOMY OF BOTHEIOCEPHALUS LATUS. 



We have already seen the importance of this discovery of the vagina 

 and its aperture for the right understanding both of the morphology 

 and physiology of the reproductive organs of Bothriocephalus. 



Since the vaginal aperture, as above noted, 

 lies at the bottom of the anterior genital 

 opening, which also includes the opening of 

 c the cirrhus-pouch, and was till Stieda's dis- 

 covery described as simply the male aperture, 

 there is a certain justification for speaking of 

 a sexual cloaca in Bothriocephalus. It must, 

 however, be kept in mind that this cloaca is 

 in nowise to be associated with the structure 

 of the same name in the Tcenice. While the 

 latter, in virtue of its depth and narrow 

 aperture, appears as a morphologically inde- 

 pendent structure, which does not alter its 

 form or character even when the penis is 

 protruded, the cloaca-like cavity in the form 

 under discussion is different, inasmuch as, on 

 protrusion of the penis, it is more or less com- 

 pletely smoothed out by the retraction of the 

 lips ; and that so far that the vaginal aperture 

 comes to lie exposed on the surface of the 

 joint, below that of the cirrhus, in a situa- 

 tion which in other species is the persistent 

 one, e.g., in B. maculatus of the leopard and 

 lion, where there is almost no genital cloaca. 

 This being so, it is perhaps more correct to 

 regard the genital pore of this worm as the 

 result of simple invagination, as Eschricht 

 had indeed done in designating the lip-like 

 marginal swelling the " prseputium." 



The Cirrhus, when protruded, is seen as a slender cone (Fig. 362), 

 not unfrequently protruding half a millimetre, or even more, out of 

 the genital aperture. It has accordingly a much more considerable 

 size than in the cystic tape-worms, in which (T. saginata) it is hardly 

 ever larger than 0'18 mm. At its base it measures in the present 

 species fully 01 mm., which is more than double its measurement at the 

 end. The canal which penetrates it, and opens at its apex, collapses 

 in the empty state, but is not unfrequently filled with spermatozoa, 

 and then occasionally measures as much as 0*02 mm. or more. 



In spite of its considerable size, the cirrhus of Bothriocephalus is 

 nothing more than the externally evaginated anterior portion of the 



FIG. 363. Longitudinal 

 diagrammatic representation 

 of the three generative ducts 

 in their connection with the 

 the genital apertures and 

 with one another, v.d., vas 

 deferens; c.p., cirrhus-pouch; 

 r., vagina ; u., uterus. 



