PLATE 9 



EXPLANATION OF FIGURES 



39 Transverse section through the heart-region of meroplast Type II, no. 

 14. On the right side of the figute will be noted a thickening Of the entoderm. 



40 Portion of the same section more highly magnified. The mass of cells 

 lying against the entoderm has evidently been proliferated by that tissue. 



ABBREVIATIONS 



Ent., entoderm Vis. mes., visceral mesoderm 



Par. mes., parietal mesoderm x, point of fusion of ectoderm and 



Pv.m., prevascular mesoderm entoderm 



148 



