MORPHOLOGY 



appears in the young plantlet, until that has established itself 

 and had time to elaborate proper material therefor. This con- 

 dition is correlated with thin foliaceous 

 cotyledons, holding no store of nourish- 

 ment. Here they do not contain sufficient 

 material for the development of the initial 

 stem and root. The maternal provision 

 for this is here stored up in the seed 

 around but not within the embryo. This 

 nourishing deposit, seen in the section 

 (Fig. 13) filling the whole space between 

 the seed-coats and the thin embryo, was 

 named by the early botanists and vege- 

 table anatomists the ALBUMEN of the seed. 1 

 This substance, softened in germination 

 and by chemical changes rendered soluble, 

 is gradually absorbed by the cotyledons 

 as material for their growth and that of 

 the developing primary stem and root. 



26. Seeds in this regard are accordingly 

 distinguished into albuminous and exal- 

 buminous, those supplied with and those 

 destitute of albumen. The difference 

 inheres neither in the character nor in 

 the amount of the maternal provision for the development of 

 the embryo-plant, but merely in the storage. In exalbuminous 

 seeds the nourishment supplied for this purpose is taken into 

 the embr} T o itself, mostly into the cotyledons, during the growth 

 and before the maturity of the seed. In albuminous seeds 

 this same material is deposited around or at least external to 

 the embryo. 



27. The amount of this deposit is, in the main, inversely pro- 



1 Grew appears to have first applied this name, and Gaertner to have 

 introduced it into systematic botany, where it remains in use, although 

 Jussieu replaced it by the term Perisperm, and Richard by Endosperm, 

 neither of them much better etymologically than the old word Albumen. 

 But it must be kept in mind that it was intended to liken the " albumen " of 

 the seed with the albumen or white of an egg as a body or mass, and not as 

 a chemical substance; the embryo being fancifully conceived to be analo- 

 gous to the yolk of the egg, the surrounding substance of this kind not 

 unnaturally took the name of the white, viz. albumen. 



FIG. 13. Section of seed of common Morning Glory, Ipomoea purpurea, dividing 

 the contained embryo through the centre. 14. Embryo of same, detached and straight- 

 ened. 15. Embryo in germination ; the cotyledons only partly detached from the coat 

 of the seed. 16. Same, later and more developed, the cotyledons unfolded and out- 

 spread as the first pair of leaves. 



