IV 



GONAD 



269 



large round nucleoli are present, frequently corresponding in number 

 with the lobes of the nucleus. 



The embryonic gonad during the stages which have been described 



^9- 



and. 



mes. 



and- 



mes. 



FlG i4o, Origin of the gonad in AmMy stoma. (After Schapitz, 1912.) A, 7-8 days 



' after fertilization ; B, 10 days ; C, 12 days ; D, 18 days ; E, 17-18 days ; F, 19 days ; 



G, just after hatching. 

 and archinephric duct ; g, gonad ; g.r, genital ridge ; mes, lateral mesoderm ; my, myotome ; spin, 

 splanchnocoele. At * in Fig. D is seen one of the heavily yolked cells which are interpreted by some 

 as accessory gonocytes. 



is not as a rule continuous from end to end. On the contrary it 

 consists of isolated pieces and these in many cases show distinct 

 traces of metameric arrangement, the pieces being directly opposite 



