ECLIPIDRILIÜ^ AND THEIR ANATOMY. 7 



The interior extremity of the ducts is free, suspended in the 

 perigastric cavity of the body, but the exterior extremity is, as usual, 

 attached to the body wall, and a part of it projects beyond the same 

 forming a retractile exterior penis proper (fig. 13. p.). The longest 

 of the two bags, which constitute the efferent duct, is the one directly 

 connected with the body wall, and is nearer its interior end furnished 

 with 3 very minute circular openings, through which the spermatozoa 

 evidently enter. 



Inside and freely suspended within this exterior duct we find 

 another interior one, of very much the same form and size as the former, 

 only it is somewhat shorter, its exterior extremity being free and not 

 attached to the body wall, nor being able to be projected through the 

 same. This extremity is furnished with a large circular opening. The 

 inner extremity of this interior duct ends blindly, and is always full of 

 spermotozoa and serve accordingly as a true seminal vesicle, in which the 

 spermatozoa are stored, before they are ejected through the sexual porus. 



The exterior duct consists of at least three different layers, one 

 exterior epithelial layer, one middle layer, much thicker than the others, 

 consisting of heavy longitudinal muscles, and one interior membranous 

 layer, which at the exterior extremity is separated from the two former 

 ones and form by itself a pellucid membranous penis, at times found 

 projected through the sexual porus. The two exterior ones of these 

 layers connect directly with the body wall of which they seem to be a mere 

 continuation. This structure of the exterior duct is the same throug-hout 

 the organ, except at the narrow tube, which connects the two sacks 

 (the seminal vescile and the atrium) which former is surrounded by 

 numerous spiral muscles, very similar to those found in Ca)iiptodrilufi ') 

 (fig. 13 & 14 spr.). 



If we therefore consider the course a spermatozoon can take, after 

 having escaped from the testes, we find that the efferent duct is most 

 admirably adopted to the purpose of transmitting and storing spermatozoa. 

 A spermatozoon after having entered the efferent duct, through one of 

 the three small circular openings (or. flg. 13 «& 14) passes down the 

 exterior duct towards the sexual porus, but is on its way intercepted by 

 the exterior opening of the inner duct (fig. 13 or. in.), and attracted by 

 the ciliated epithelium of its inner surface, ascends through the exterior 

 part of the duct (fig. 13 in) up through the narrow tube and is finally 

 lodged in the seminal vesicle, and is here stored untill of future use. 



') Freiiiiiiiiari/ Report on Tuhificidœ. ßihaiig till K. Vet.Akad. Havidl. Bd. 5. N. 16. fig. 6. 



