i 7 8 



NEMATHELMINTHES 



retinaculum ; in the male they are in connexion with a special 

 genital ganglion which lies' near the ductus ejaculatorius. 



With the exception of certain 

 sensory papillae in the neighbour- 

 hood of the male genital orifice, and 

 of three similar papillae mentioned 

 by Kaiser on the proboscis, the 

 Acanthocephala are devoid of sense 

 organs. 



The Acanthocephala are dioecious ; 

 their generative organs are developed 

 in connexion with the ligament, 

 a cord-like structure which arises 

 between the inner and outer layer 

 of the hinder end of the proboscis 

 sheath and traverses the body-cavity, 

 ending posteriorly in connexion with 

 the genital ducts. The testes lie 

 in this ligament ; they are paired 

 oval bodies which open each into a 

 vas deferens. The vasa deferentia 

 each bear three lateral diverticula, 

 the vesiculae seminales ; and three 

 pairs of cement glands pour their 

 secretion into a duct which opens 

 into the vasa deferentia ; the latter 

 unite and open by a penis which 

 is withdrawn into a genital bursa, 

 FlG ; 9 t^SI^ i0 l t ^ but is capable of being extruded. 

 Zed. (From Hamann.) a, Probo- The two ovaries are formed in 



scis; b, proboscis sheath ; c,retrac- ,, lio-ampnr of thp fpmalp in a pov 

 tor of the proboscis ; d, cerebral tne ligament oi tne lemaie in a C01- 

 gangiion ; /, /, retractors of the responding position to that occupied 



proboscis sheath ; a, g, lemnisci, , , .. , , 



each with two giant nuclei ; * h Y the testeS m the male > but at an 



space in sub-cnticniar layer of early stage they break down into 



the skin; I, ligament; m, m, / n - i i ,1 e 



testes ; o, glands on vas deferens ; packets Ot Cells, ol which those Ot 



p, giant nucleus in skin ; q, open- t j ie peripheral layer develop into ova 



ing of vas deferens. x * in ^ -, 



at the cost of the central cells, which 

 serve them as a food supply. As these masses grow and 

 increase in number they rupture the walls of the ligament, and 

 escape into the body-cavity, in which they float. The ova are 



