BIGELOW : EARLY DEVELOPMENT OF LEPAS. 



135 



TABLE OF THE CELL-LINEAGE OF LEPAS. 



1 ceU. 



Fertilized 

 Ovum 



2 ceUs. 



(1) 





b^ 



(2) 





4 cells. 8 cells. 



ai-^(ec'bl.) 



,4.1 



M-^ (ec'bl.) 



c*-2 (ec'bl. 



rfi-2 [ec'bl.) 

 (3) 





IG cells. 



flS-l (ec'W.) 



65-1 (ec'6/.) 



^5.2' 



c^-i (ec'bl.) 

 d^-"^ (ms'bl.) 



(/■^•i (en'W.) 



32 cells. 



flG-* (ec'6;.) 



i6-3 



h'i-i 



lfi.3 



c6-4 (ec'W.) 



6-3 



C°"' 



62 cells. 



a'-6 (ec'W.) 

 a^-^(ms'bl.') 

 b'^-^ (ec'bl.) 

 b'-' (ms'bl.') 



b'-^ (ms'bl.') 



c"-6 (ec'6/.) 

 cT-5 (ms'bl.') 



y", y^, y*, y^ designate the yolk-bearing raacromere; (1), (2), (3), the three 

 micromeres containing ectoblast ; ec'W., ectoblast; e/j'W., entoblast ; ms'bl., 'pvima.ry 

 mesoblast , ms'bl.', " secondary mesoblast." 



