SECTION 3.] 



SEEDLINGS. 



21 



Some seeds have very little of this deposit, but a comparatively large em- 

 bryo, with its parts more or less developed and recognizable. In others 

 this deposit forms the main bulk of the seed, and the embryo is small or 

 minute, and comparatively rudimentary. The following illustrations exem- 

 plify these various grades. When an embryo in a seed is thus surrounded 

 by a white substance, it was natural to liken the latter to the white of an 

 egg, and the embryo or germ to the yolk. So the matter around or by 

 the side of the embryo was called the Albumen, 

 i. e. the white of the seed. The analogy is not 

 very good ; and to avoid ambiguity some botan- 

 ists call it the ENDOSPERM. As that means iu 

 English merely the inwards of a seed, the new 

 name is little better than the old one ; and, since 

 we do not change names in botany except 

 when it cannot be avoided, this name of albu- 

 men is generally kept up. A seed with such a 

 deposit is albuminous, one with none is exal- 

 buminous. 



32. The ALBUMEN forms the main bulk of 

 the seed in wheat, maize, rice, buckwheat, and 

 the like. It is the floury part of the seed. 

 Also of the cocoa-nut, of coffee (where it is dense 

 and hard), etc. ; while in peas, beans, almonds, 

 and in most edible nuts, the store of food, al- 

 though essentially the same in nature and in 

 use, is in the embryo itself, and therefore is not 

 counted as anything to be separately named. 

 In both forms this concentrated food for the 

 germinating plant is food also for man and for 

 animals. 



33. For an albuminous seed with a well-developed embryo, the com- 

 mon Morning Glory (Ipomcea purpurea, Fig. 40-43) is a convenient exam- 

 ple, being easy and prompt to grow, and having all the parts well apparent. 

 The seeds (duly soaked for examination) and the germination should be 

 compared with those of Sugar and Red Maple (19-21). The only essen- 

 tial difference is that here the embryo is surrounded by and crumpled up in 

 the albumen. This substance, which is pulpy or mucilaginous in fresh 

 and young seeds, hardens as the seed ripens, but becomes again pulpy in 

 germination ; and, as it liquifies, the thin cotyledons absorb it by their 



FIG. 40. Seed of Morning Glory divided, moderately magnified; shows a longi- 

 tudinal section through the centre of the embryo as it lies crumpled in the albu- 

 men. 41. Embryo taken out whole and unfolded; the broad and very thin 

 cotyledons notched at summit ; the caulicle below. 42. Early state of germina- 

 tion. 43. Same, more advanced; caulicle or primary stem, cotyledons or seed- 

 leaves, and below, the root, well developed. 



