THE SEED 5 



distinguishable as a white patch. In maize or barley 

 which has been soaked for a few hours in water, the 

 embryo may be readily separated from the rest of the 

 seed, when it will be seen how large a part of the seed 

 is occupied by the store of plant food. 



This separate store of plant food is often spoken of 

 as the albumen* and seeds are described as albuminous 

 or exalbuminous in accordance with the presence or 

 absence of this albumeru The seeds of wheat, barley, 

 maize, all the cereals and grasses, beet, carrot, buck- 

 wheat, marvel of Peru, onion, and date, afford examples 

 of albuminous seeds. 



If we now refer again to the seed-leaves or cotyledons 

 which exist in every seed, we have to note that the 

 embryos of some seeds have two cotyledons, as in the 

 case of the bean and buckwheat, while the embryos of 

 other seeds have only one. Barley, wheat, or maize may 

 be taken as examples of the latter class. In some 

 cases it is an easy matter to ascertain whether one or 

 two cotyledons are present in the seed, while in others 

 it is matter of some difficulty. It is found that the 

 presence of either one cotyledon, or of two cotyledons, 

 is usually associated with other constant characters of 

 plant structure to which fuller reference is made later. 

 Seeds with embryos having one cotyledon are described 

 as monocotyledonous, while those in which two cotyledons 

 are present are known as dicotyledonous. 



* The term "albumen" is an unfortunate one, as the same 

 term is commonly employed to denote a large class of chemical 

 substances. There should be no difficulty, however, in under- 

 standing the limited sense in which it is employed here. 



