SEXUAL ORGANS OF CCELENTEEATA. 



123 



§ 07. 



The generative organs of the Anthozoa are very similar in cha- 

 racter. They are connected with the gastric cavity, so that the gene- 

 rative matters pass to the exterior through the gullet. The septa 

 of the gastric spaces, or their ridges, which project into the central 

 stomachal cavity, generally function as organs of this kind. In 

 the Alcyonarians the sexual products are formed at the free edge 

 of these processes, either in the stomach or at some distance from 

 it, at the base of the gastric space; two septa are sterile. They 

 are distinguished by the presence of the ridges mentioned above, 

 (§ 93), which project some way forwards. The other ridges do not 

 always carry sexual products, for in many Alcyonarians they are 

 found on four only, or only on two of them. In the Actinias the 

 generative products are formed within the gastric ridges. The same 

 thing happens in the Antipatharia (Gerardia). The Madreporinse, 

 also, may be mentioned here, for in them the generative products 

 are developed in the ridges, which project far into the base of 

 the gastric cavity, and they there form a special process on each of 

 the two surfaces of the ridges (Astroides calycularis) . 



The sexes are usually separated, and in different persons, but 

 there may be hermaphrodites also (Cerianthus). In the colonial 

 forms both dioecious and monoacious conditions have been observed ; 

 in others these characters vary very greatly (Corallium rubrum). 

 When the persons of a colony are dimorphic, those which are the 

 more developed are at the same time those which are functionally 

 sexual, while the others are sterile. But in some Peimatulida3 the 

 persons without tentacles are 

 the only ones in which there 

 are generative organs (Virgu- 

 laria mirabilis). 



§ 08. 



Ha 



In the Ctenophora the 

 peripheral portion of the gas- 

 tric system represents the 

 genital region. Cascal diver- 

 ticula are developed from the 

 sides of the canals which run 

 parallel with the rows of nata- 

 tory lamellae ; in these semen 

 or ova are formed. One side 

 of a canal is beset with 

 . ovarian follicles, and the other 

 with testicular lobules. Hermaphroditism repeats itself therefore 

 in each of the radial segments of the body. The gastric system 

 serves to carry the generative products to the exterior. This 



:?^%© 



Fig. 50. Generative organs of Beroe rufes- 

 cens ; showing their relation to a tract of the 

 radial canal, a Stripes running along the 

 canal (Muscles F) b Semen-producing side, 

 c Ovarian side, with eggs (after Will). 



