PLATE 22 



EXPLANATION OF FIGURES 



86 Section through the yolk sac of a chemically treated embryo showing 

 the position of a transplanted cephalic meroplast. 



87 The same section of the meroplast more highly magnified showing an 

 otic capsule, and mesenchyme devoid of erythrocytes. 



88 A section through the anterior-most region of the meroplast showing the 

 axial portion to be solid cartilage. 



89 Section between the planes of figures 87 and 88, more highly magnified 

 showing mesenchyme cells in various stages of transition into erythrocytes. 



' ABBREVIATIOXS 



Cart., cartilage Gng., mass of ganglionic tissue 



E., eye Ot.c, otic capsule 



Erth., erythrocytes Otcst., otocyst 



Erthbl., erythroblasts F.-s.. yolk sac 



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