GROWTH AND WORK OF PLANTS 



film or remnant which dries. The food stored in the seed here 

 has, therefore, been completely used up by the embryo during ger- 

 mination, and the cotyledons have served as the absorptive organs 

 for this food. 



Fig. 10. 



Seedlings of castor-oil bean casting the seed coats, and showing papery remnant of the 

 endosperm. 



7. The embryo of the castor-oil bean presents a type very 

 different from that of the bean as we can readily see by a com- 

 parison. Yet the two types so different in form and structure 

 are very similar when we consider the relation of the food sub- 

 stance to the cotyledons and the function of the latter in absorption 

 of this stored food. It should not be difficult now to understand 

 how the embryo of the bean and pea during the formation of the 

 seed can absorb the endosperm through the cotyledons though 

 it is stored in the cotyledons as food for the embryo during 

 germination and the early stage of the seedling. 



