50 



THE TAPE- WORM 



Posteriorly the uterus joins the yolk-duct from the yolk or vitelline gland. 

 From the junction of the oviduct and uterus with the yolk-duct the vagina 

 originates. At the junction of these ducts lies the shell-gland. The vagina 

 passes forwards and then to the side, to open by the female genital aperture 

 within the genital atrium, which is situated at the genital papilla on one 

 side of the proglottis. 



(b) Male organs. 



The testes consist of numerous rounded lobes occupying the greater part of 

 the sides of the proglottis. A fine efferent duct leads from each lobe ; and these 

 ducts (vasa efferentia) eventually unite into a vas deferens, which passes along 

 parallel to the vagina and opens by the male genital aperture within the genital 

 atrium.' The vas deferens is slightly swollen near its end into the vesicula 

 seminalis. 



Nervous System. 



This system is represented in the proglottis by two lateral nerve cords 

 passing backwards through all the proglottides, and on the outer side of the 

 main excretory canals. 



Excretory System. 



This is shown by a pair of longitudinal lateral excretory canals which pass 

 backwards along the whole length of the animal. These are connected by a 

 transverse canal in the posterior part of each proglottis. The excretory system 

 is of the same type as that of the Liver-fluke. 



Testis 

 Excretory canal 



Qviduct Ovary 



Uterus / yagina /• 



Circular muscles 



Cuticle 



Lateral nerve 

 Longitudinal muscles 



Fig. 18. — Transverse Section through a proglottis of Taenia solium (about the 

 position indicated by the arrow in Fig. 17). 



Transverse Section of a Proglottis. 



In a transverse section through a proglottis (as indicated by the arrow in 

 Fig. 17) the following structures will be seen : — 



{a) The cuticle, the smooth thick covering layer. 



(J) The cells of the ectoderm, extending inwards from the surface. 



(c) The longitudinal muscles. 



(d) The circular muscles. 



