86 postetsta 



the junction of the stem and root. 

 Conditions later arising made it nec- 

 essary for the stem and root to come 

 out on the same surface of the gameto- 

 phyte, when only one side of this 

 cotyledonary ring could remain em- 

 bedded in the prothallium. The dif- 

 ferent positional relations which the 

 various embryos bear to the gameto- 

 phytes would bring different portions 

 of the cotyledonary ring into favorable 

 positions to function. In the seed the 

 embryos of Angiosperms are brought 

 under conditions which seem to stim- 

 ulate development throughout almost 

 the entire cotyledonary ring. 



