74 



[chap. 



Transverse Section through the Dorsal Eegion of an Embryo op 



45 hodrs. 



A. epiblast. B. mesoblast. C. hypoblast consisting of a single row of flat- 

 tened cells. M. c. medullary canal. P. v. prntovertebra. W. d. Wolffian 

 duct. S. 0. Somatopleure. <S'. p. Splanchnopleure. p. p. pleuroperitoneal 



