494 THE PHYSIOLOGY OF REPRODUCTION 



l)last(>ev.st and the small amniotic and liypciblastic \'esic]es. In the 

 ovum desciiljed liy Leopold,^ it was already split l>y the " Haftstiel " 

 iut(j two parts, which enclosed tlie cielom and were continuous with 

 eacli other (Fig. 149). The outer wall of tlie blastocyst, tlie foetal 

 ectod.erm nv trdjiliohlast whicli anchors the dviuu in the mucosa, is 





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thickened all mund its circumference, and even in the earliest 

 specimen contained ^'acuoles into some of which maternal Ijlood had 

 penetrated. In this thick spongy layer Bryce and Teacher found no 

 cell-outlines an)'where. Hence the transformation to syncytimn is not 

 due, as Peters supposed, to the contact with maternal Idood. Under 

 the sT|-ncytium is the cellular layer, correspon<ling to the cytol5last of 



' Leopold, " Demonstration eines sehr junijen mensulilichen 'Eiefi" J rhritca 

 a>i.< ,/. Kiiimil. Fr.iiiridliink n, I ),;'f.h:ii , Leipzig, lOOfi. 



