REPRODUCTIVE SYSTEM. 113 



submerged objects. The testicle resembles in general feat- 

 ures the ovary. The gland is composed of numerous con- 

 vergent cylinders ; is enclosed in a loose membranous capsule 

 from which emerges the slender tortuous vas deferens. The 

 tube terminates in mantle near rectum, a small intromittent 

 organ protruding. The canal at lower portion is of varying 

 degrees of thickness. A single conspicuous glandular body 

 (prostate) and a muscular chamber (Needham's pouch) being 

 appended. This latter cavity is occupied by whitish filaments 

 (spermatophores), each having an average length of half an 

 inch. Each filament contains a convoluted tube occupying 

 the greater part of the cavity, which is filled with spermatic 

 particles and connected anteriorly to a solid cylindrical body 

 continuous behind with a spiral ligament. This latter is en- 

 closed within a thin sheath which is attached to the end of 

 the sac. The escape of the sperm from this apparatus is ef- 

 fected during coition by the rupture of the anterior extremity 

 of the filament, when the contents are forcibly ejected by- 

 the action of the spiral ligament. 



In Aryonauta (paper nautilus) the male organs are upon the 

 same type as those already described, but the manner by 

 which their product effects union with the female is peculiar.. 

 The spermatophore is lodged in the base of one of the arms, 

 which, upon the former becoming charged with filaments, is 

 spontaneously severed from its connections. It now receives 

 the name of the Heetocotylus, and floats off in search of the 

 female. 



ARTICULATA. Entozoa. See p. 161. 



Rotifera. Organs simple. Ovary opens by oviduct into- 

 cloaca. Male organs unknown. 



Annelida. Genital apparatus of various forms. In Lum- 

 brictcs (earthworm), which is hermaphroditic, the male and : 

 female organs resemble one another very closely. Their 

 orifices are situated in pairs upon the ventral surface at the 

 anterior extremity of the body, surrounded by a thickened 

 circular fold of integument. The capitobranchiates and 

 dorsibranchiates are of distinct sexes. The organs i which 

 project from the ventral surface into the cavity of the bodjr 



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