PHYLUM PLATYHELMINTHES 



245 



can ejccrct. 



nc.ru. I 



main trunks of the excretory system give origin to a number of 

 branches, and these in turn give off numerous fine canalicules, or 

 capillaries, terminating in flame-cells, similar to those of the 

 Fluke. 



The reproductive organs (Fig. 197), repeated in each fully 

 formed proglottis, are in essential respects very similar to those of 

 the Liver-Fluke. In the most anterior proglottides they are not 

 developed ; it is only at about the 200th proglottis that they first 

 appear : at first the male parts of the system are alone differen- 

 tiated ; then in the succeeding proglottides, till we approach near 

 the posterior extremity of the body, the female organs are like- 

 wise developed. In the most posterior segments modifications 

 and reductions of some of the parts take place, owing to the great 

 increase in size of the uterus. The male portion of the apparatus 

 consists of the testes with their efferent ducts, the vas deferens 

 (vas. def.), and the 

 cirrus, with its sac. 

 The testes consist of 

 numerous rounded 

 lobes situated 

 nearer the dorsal 

 than the ventral 

 surface, and ex- 

 tending throughout 

 the greater part of 

 the length and 

 breadth of the pro- 



glottis. With each 

 lnVp ie rrmrippi-prl a 



fine efferent duct ; 



, j , r -i 

 the ducts OI neign- 



bouring lobes unite 



together to form somewhat larger ducts ; and the larger ducts, 



receiving numerous tributaries, eventually open into the inner 



extremity of the vas deferens, or main duct of the testis. The 



vas deferens is a convoluted tube which extends outwards towards 



the lateral margin (right or left as the case may be) of the 



proglottis. 



The terminal part of the vas deferens, which is somewhat 

 narrower than the rest, traverses a narrow protrusible process, the 

 cirrus, and opens at its extremity by the male genital aperture in 

 the genital atrium or cloaca. The cirrus is enclosed at the base 

 by a muscular sac, the cirrus-sac. 



The ovary (germarium) (ov.) differs from that of the Liver- 

 Fluke in being a paired organ, consisting of two approximately 

 equal, right and left, halves. It is situated towards the posterior 

 border of the proglottis. Like that of the Liver-Fluke, it consists 



par g 



i97._A proglottis of Tsenia solium with mature repro- 

 ductive apparatus, can. excrct. longitudinal excretory canals 

 with transverse connecting vessels ; gl. vit. vitellinc glands ; 

 nerv. 1. longitudinal nerves ; or, ov. ovaries (germaria) ; por. 

 ffen. genital pore; scMd. shell-glands; uter. uterus; ran. 

 vagina ; tas def. vas deferens. The numerous sninll round 



