PLATE 8 



EXPLANATION OF FIGURES 



37 Transverse section through trunk of meroplast Type II, no. 88, showing 

 the proliferation of endothelium by visceral and by parietal mesoderm. 



38 Section posterior to the plane of figure 37, and more highly magnified. 



ABBREVIATIONS 



Ect., ectoderm Ent., entoderm 



Endth., endothelium Pv. mch., prevascular mesenchyme 



146 



