STUDY OF SPIRAEA 459 
The embryo sac follows the normal order of development, 
at an early stage there occurs a thickening of cells in the 
al region adjacent to the megaspore (fig. 26), and this 
ds until it includes the whole of the layer of integument 
embryo sac are rich in food material, 
ly starch. 
THE EMBRYO. 
8) . Their purpose is evidently that es : 
ting the food supply derivedfromthe == © 
