



■^^*^' 



<- ) 



Pb 



• .^t. 



32 



Fig. 31 Section through the trunk region of a seventy-two hour embryo 

 without a circulation; Experiment A, 1913. The extreme anterior end of the 

 intermediate cell mass, icm, is represented by deeper staining cells between the 

 notocord and intestine, Int; the primary kidney ducts, WD, are lateral to the mass. 

 ^- Fig. 32 Represents a more posterior section through the same embryo; 

 in this region the intermediate cell mass, icm, is more extensive in cross-section 

 and its cells are further differentiated than those in the more anterior region, 

 Pb, periblastic material and large nuclei between the embryo and the yolk. 



263 



THE AMERICAX JOURNAL OF ANATOMY, VOL. 18, NO. 2 



