504 COMPARATIVE ANATOMY AND PHYSIOLOGY. 



Though the germ glands of the higher Mollusca 



are simple and similar in 

 structure, there is in some 

 a very complex system of 

 accessory organs. In the 

 hermaphrodite forms the 

 duct remains common for 

 a short distance only, and 

 its tract becomes compli- 

 cated by the development 

 of glandular bodies, the se- 

 cretion of which nourishes 

 or protects the ova, and of 

 pouches, in which the sperm 

 received during copulation 

 can be stored up till the 

 ova are ready for fertilisa- 

 tion. The male portion has 

 connected with it glands, 

 by means of which the 

 spermatozoa are massed into 

 spermatopliorcs, and 

 the integument is invagi- 

 natedto form a penis, which, 

 when turned inside out, 

 forms a duct for the sperm. 

 In some cases also, as in 

 the snail, each individual 

 is provided with a gland 

 which secretes a chitinous 

 F\g. 209. Male Duct of Loiigo dart-like body (dart sac), 



vulqaris. i i J.T w c 



winch is thrown on from 



o, Penis ; 6, pouch of Needuam ; c, vas 



efferens ; d, caecum ; e, prostate ; each Sliail at its mate 

 /, vesiculaseminahs ; .<?, vas defer- . 



ens ; h, its opening into capsule m the preliminary StagCS 

 of testis. (After Brock.) ^ . J 



or copulation. 



In some Cephalopods there is a still more remark- 

 able provision for the safety of the seminal products. 



