580 



CRESSWELL SHEAT^ER. 



the head-kidney has formed, and the mesoderm cell is seen 

 wedged in between the anal vesicle and the head-kidney. 



The growth of the bands from these cells is not that of a 

 true teloblastic one; when tlie cojloniesoblast cells start to 

 diviile they do so quite irregularly. The bands at first consist 



Text-fig. 27. 



StiTVS' 



^: 



ces. 



,M^''m^ 



j_ _m«5c. 



coe.Tnr 





; ~ - ~ hk. 



4y - ^. an..v. 



Section thvougli trocliophore of Eupomatns older thim those of 

 tlie foregoing figures, un.v. Anal vesicle, cce.m. Ccelonieso- 

 blast. (J. Gut. \h. Head kidney, //le.sc. Mesenchyme or ecto- 

 mesoblast. Aiuii. Stomach. 



of grcjups of tliree or four cells; they divide in all directions, 

 so that after the iirst divisicm it is not pcssible to speak of a 

 pole-cell, the divisions always being equal. Hatschek's rather 

 elaborate account of the origin of the bands by tek)blastic 

 growth conveys quite an erroneous impression of the ])i-(icess. 

 The ccehjinesoblast cell first divides into two equal cells, and 



