56 GENERAL BOTANY 



But this splits open at the caruncle end, and we can 

 easily remove it. Then we find not an embryo with 

 two white cotyledons as in the Beans, but a white 

 body with a thin papery covering, from one end of 

 which the micropyle end there breaks out through 

 it the tip of the radicle. The radicle, we must note, 

 is not a part of the white body, but breaks through 

 it from inside. 



Splitting this body open carefully we shall find the 

 embryo inside. 



Its cotyledons are very thin, thinner at first than 

 the thinnest paper, but as germination proceeds they 

 become thicker and larger until they may each be 

 four times as long and broad as the seed from which 

 they came out. Their leaf -nature is indicated from the 

 very first, by the lines with which they are marked 

 exactly as leaves are. 



In the seed, therefore, there is something else besides 

 the embryo, enclosing it. This substance is called 

 the endosperm, and it is packed tight with oil and 

 substances of a mineral and proteid nature. In the 

 process of germination the endosperm absorbs water, 

 swells and becomes soft, and the oil and other food 

 substances in it are absorbed by the cotyledons. Thus 

 it is that these, though at first as thin as paper and 

 only quarter inch long, become eventually over an inch 

 in length and comparatively thick, while the endosperm 

 itself becomes soft and slimy and is gradually absorbed 

 till there is left only a skin which finally falls off. 



Comparing the Bean and the Castor-seed we see 

 that in both there is food-material stored up for the 

 young plants; but in the Bean it is in the cotyledons 



