THE EARTHWORM 



113 



removal of the dorsal wall of this median region will disclose four large 

 bodies, rather indistinct in outline, but different in texture from the 

 vesicles and resembling crumpled bits of paper. These are ciliated 

 funnels of the male ducts, or ductus efferentes (vasa efferentia). Look 

 on the ventral body wall and find the ductus efferens which passes 



■seminaf 

 receptac/c 



testis 

 sc/7>/na/ v^e5/'c/e5 



auctas efferene 



o\/ary 

 cfuctas c/eferen5 



o\^/cfact 



neri^e core/ 

 nephr/af/am 



Fig. 56. — The reproductive system of the earthworm. A, an ovary with 

 oocytes in various stages of growth, the terminal one about ready for detach- 

 ment from the ovary. B, dorsal view of the reproductive system with the 

 cavities of the seminal vesicles of the right side exposed. C, an egg-capsule. 

 D, multinucleate cell which is detached from the testis and from which 

 spermatozoa differentiate within the seminal vesicles. E and F , the spermatids 

 on the surface of a central mass of cytoplasm from the original multinucleate 

 cell (D). G, two spermatozoa as they appear attached to the surface of this 



spherical mass of cytoplasm. 



laterally from the region of each funnel. The two ductus efferentes 

 unite in somite 12 on each side to form the ductus deferens (vas def- 

 erens) which passes posteriorly to its opening on somite 15. The male 

 germ cells begin their differentiation in the testes, bodies somewhat 

 similar to the ovaries and in the same relative position in somites 10 

 and 11. Although the testes lie close to the funnels of the ductus 



