504 



CHARLES H. SWIFT 



^ at.sp. 



r"''^-°- 



Fig. 5 Portion of a transverse section through the head region of an embryo 

 with 25 somites. Aleves' fixation and Meves' iron-hematoxylin stain. X 787. 

 pr.o., primordial germ-cell; pr.o'., primordial germ-cell dividing; a^sp., 'attraction- 

 sphere of germ-cell; bl.c, blood cell;/.fe., fore-brain. 



