DICOTYLEDONS 95 



Sketch them under the lens, showing the delicate venation. 

 Is there any plumule ? 



Test the endosperm with a little iodine to see if it 

 contains any starch. Crush a bit of it on a piece of white 

 paper and see if it leaves a grease spot. What does this 

 show that it contains ? Test the embryo in the same way, 

 and see whether it contains any oil. 



124. Arrangement of the Embryo. Notice the difference 

 in the way the embryo is packed in the castor bean, and 

 in such seeds as the cotton, okra, and maple. In the 

 former it is said to be straight, while in the latter it is 



215 216 217 218 



215-218. Arrangement of embryo in endosperm (GRAY): 215, morning-glory; 

 216, barberry ; 217, potato ; 218, four o'clock. 



folded or plicate. In different seeds it may be coiled and 

 folded in many different ways. It may also be packed 

 within the endosperm, as the castor embryo, or coiled or 

 wrapped around it, as in the chickweed. 



125. Storage of Nourishment in the Seed. In the various 

 seeds examined we have seen that the nourishment for 

 the young plant is either stored in the embryo itself, as in 

 the cotyledons of the bean, acorn, squash, etc., or packed 

 about them in the form pf endosperm, as in the corn, 

 wheat, and castor bean. 



The latter are classed by botanists as albuminous, the 

 former as ex-albuminous the word "albumin" referring not 

 to the chemical composition of the food supply, but to its 

 office, which is similar to that of the albumen, or white of 

 the egg stored up for the nourishment of the hatching 

 chick. The older botanists, recognizing the analogies 

 between the seed and the egg, and not understanding the 

 true nature of either, regarded the seed as a sort of vege- 



