FERTILIZATION AND DEVELOPMENT OF SEED 203 



by the walls of the ovule; the embryo and endosperm with the 

 enveloping ovule walls make the seed; but in the grain of 

 wheat, corn, etc., the wall of the ovary is joined with the walls 

 of the ovule and the seed is permanently enclosed by the ovary, 

 thus forming a fruit (see paragraph 328 and footnote, page 19). 

 In the water lily, the pepper, and some other plants, a part 

 of the interior of the ovule is left in the seed. This is called peri- 

 sperm when it is present in the seed, so that in such a seed there 

 are embryo, endosperm, and perisperm surrounded by the integu- 

 ments or ovule walls. 



321. Albuminous and exalbuminous seeds. In the study 

 of the substances stored in the grain of corn and wheat it was 

 found that there is a large quantity of starch and protein (para- 

 graph 26) in the endosperm. The protein is an albuminous 

 substance. Seeds containing endosperm at ripeness are called 

 albuminous* seeds, while those like the bean, pea, etc/ with no 

 endosperm are called exalbuminous. 



* Strictly speaking, the starch and other non protein substances of the 

 endosperm, are not albuminous, but in botany any nutritive substance in 

 seeds for the use of the embryo is called albumen, whether in the form of 

 starch as in the cereals, oil as in nu.ts, a bony substance as in vegetable ivory, 

 horny as in coffee, etc. 



