234 



ZOOLOGY 



SECT. 



slender nerves pas-ing from these to the suckers, and of two 

 lonyitvil'uml iierecs which run backwards through all the proglot- 

 tides to the posterior end of the body. The ganglia obviously 

 correspond t<> the ganglia on the nerve-ring of the Liver-Fluke. 



The excretory organs consist of a richly branched system of 

 excretory vessels. There are four main trunks ( Fio-. ] S8, can. cxcn f. }. 



. O 



which extend throughout the entire length of the body, two near 

 each lateral margin. The two pairs of longitudinal vessels are 

 connected together in the head by a ring-like vessel, and in each 

 proglottis near its posterior margin by a straight, transverse, 

 connecting branch. Posteriorly the longitudinal trunk opens into 

 a pulsatile caudal vesicle, communicating with the exterior. These 

 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 Distomum 

 hepaticum. 



The reproductive organs (Fig. 183) repeated in each fully 

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



can.excreb 



ca.n.ejccret 



ne.rv.1 



ov 



PIG. 1S3. A proglottis of Taenia sotium with mature reproductive app trutu^. can. 



longitudinal excretory canals with transverse connecting vesseK : ."'. vit. vitelline glan<l- : 



r. I. longitudinal nerves: if. n,\ ovaries; f>'>,\ ii,,>. genital pore; .<>!, l<i. shell-glands; 



uter. uterus: <.<. vagina: vat. <><?. vas deferens. The numerous small round bodies are the 



1. ilio ..f the te.~te-. (After Leuckart.) 



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 testcs with their efferent ilmis, the vas deferens (vas. 

 def.\ and the cirrus or ////.>-. with its *r-. The testes consists of 

 numerous rounded lobes situated nearer the dorsal than the ventral 



