188 



COiMPAEATIVE ANATOIMY. 



-ad 



Fig. 92. Generative organs of the Earth-Worm. The 

 portion of the body which contains these organs is opened 

 from above, and the walls ai'e laid out on either side. 

 Segments VIII.-XV. are figured, n Ventral ganglionic 

 chain, s s' s" Diverticula of the testes, rd Their efferent 

 ducts. Ovary, ad Ovarian ducts, rs Receptaculuni 

 seminis (after Hering). 



Eacli pair of testes has a seminal vesicle of this kind (Fig. 92, s's"), 

 whicli is placed across the middle line, and is further provided with 



lateral diverticula. 

 y^ . h \ ^ \ \ In each of these, 



two funnel-shaped 

 organs are placed, 

 which are continued 

 laterally into the 

 semiual ducts. The 

 two seminal ducts 

 of either side unite 

 into a common duct 

 (-yJ), which extends 

 backwards, and 

 opens laterally on 

 the ventral surface. 

 In the same meta- 

 mere there are two 

 pi'otractile copula- 

 tory organs, de- 

 veloped from mo- 

 difications of the 

 setisrerous follicles. 

 The ovaries (o) are the smallest organs of the female portion of the 

 generative system. They lie behind the second pair of testes and 

 on each side of the ventral nei've-chord. Behind them two ovi- 

 ducts [ad) are attached to a dissepiment, and begin by two wide 

 abdominal ostia; they pass to the exterior by a short canal placed 

 in the segment in front of the openings of the male organs. Several 

 pairs (generally two) of seminal pouches (receptacula seminis) (rs) 

 are also present. They are large, rounded organs, which lie near 

 the testes, and open by a short duct, without having any close rela- 

 tions to the male apparatus. The paired character of the geiiital 

 pores, the position of the female one iu front of the male, and, 

 finally, the connection between the testes of either side, form an 

 arrangement which, so far as is yet known, has not its like among 

 living allied forms. 



Even iu the LimicolfB the organisation is different. The two 

 kinds of generative organs, which are here also present in one 

 individual, have no proper efferent ducts. We may suppose that 

 the system of oviducts, seminal ducts, and seminal vesicles, which is 

 found in the Lumbricidte is not developed in them, so that there 

 are only ovaries, testes, and receptacula seminis. So far as we can 

 see at present, some of the looped canals (cf. p. 177), which in the 

 Lumbricidfe have nothing to do with the generative system, here 

 form the efferent ducts for the reproductive matters, and undergo 

 changes in correspondence with this function. Parts of the dis- 

 sepiments function as germ-glands, on which the generative 

 products when undeveloped generally form paired saccular diver- 



