Arthur W. Meyer 1G5 



» 



of these vesicles and those from embryos of the third month plainly 

 shows that the condition of the vesicle as found at birth is reached early 

 in the life of the embryo. 



The occasional large size of the umbilical vesicle in full-term placentae 

 which contained a normal foetus, is very remarkal)le. I have seen vesi- 

 cles that measure fifteen by ten millimeters. Such occurrences are hard 

 to reconcile with the supposition that the umbilical vesicle reaches it? 

 greatest development in the fourth week. oSTor is it easy to see how 

 mechanical forces can produce these large inflated vesicles. The only 

 suggestion that occurs to me without further study of full-term vesicles, 

 is that hypertrophy takes place at the time when the transformation of 

 the wall of the original vesicle into fibrous connective tissue occurs. 



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