BIGELOW: EARLY DEVELOPMENT OF LEPAS. 



135 



TABLE OF THE CELL-LINEAGE OF LEPAS. 



1 cell. 



2 cells. 



4 cells. 



8 cells. 



16 cells. 



32 cells. 



62 cells. 



Fertilized 

 Ovum 



(y 3 ) 



'bL) 



r.5-2 



6*- 2 (ec'W.) 



65-2 



65-1 (ec'W.) 



a 6-8 



iB-4 



66-3 



c 6-3 



<*! (ec'bl.) 



a7- (ec'W.) 



67-7 



67-6 (ec'bl.) 



67-5 ( m 'W/ 



y 2 , y 8 , ?/ 4 , y 5 designate the yolk-bearing macromere; (1), (2), (3), the three 

 micromeres containing ectoblast ; ec'bl., ectoblast; en'bl., entoblast ; ms'bl., primary 

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



