76 lPostelsta 



yledon is enclosed in a non-living 

 movable seed-coat. The problem 

 of food storage in the seed is met 

 in the various well known ways 

 by different Angiosperms. The primi- 

 tive methods of storing it in the 

 megaspore and gametophyte were no 

 doubt first supplanted by the forma- 

 tion of the perisperm and endosperm, 

 but a more advanced condition is 

 arrived at in exalbuminous seeds where 

 the food-materials are stored directly 

 in the tissues of the young embryo 

 rather than in an intermediate structure. 

 In the seed the cotyledon neces- 

 sarily assumes new functions and a 

 greater importance due to the extended 

 embryonic period. Primarily a nursing- 

 organ, it readily assumes the additional 

 function of a storage -organ, accommo- 

 dating itself to the available space 

 within its investments. The multifari- 



