90 SEED. 



a. The seed consists of the nucleus^ or kernel, and its integu- 

 ment^ or covering. The eye of the seed^ or Kilmn^ is the scar 

 formed by the separation oi\h.(ifunlde. This connecting mem- 

 brane is nsnally very short ; but in the magnolia^ and some 

 other phxnts, it is several inches in length. A7hen the seed 

 is fully ripe, its connection with the ])ericarp ceases by the 

 withering and separation of the funicle, leaving upon the outer 

 surface of the seed tlie mark of its insertion. 



This scar, or eye, is very conspicuous in the bean, which also exhibits 

 the pore (foramen) through which the nourishment was conveyed to the 

 internal parts of the seed, Tliat part of the seed which contains the eye 

 is called tlie base ; the part opposite is called the apex. Fig. 115 rep- 

 resents the garden bean ; it is an oblong, tunicated seed, with two thick 

 cotyledons ; at a may be seen the hilum, or eye. 



The integument is called the spermoderm (from sperm^^ seed, 

 and derinci^ skin) ; it consists of three coats, the external shin^ 

 called the testa or cuticle^ the cellular tissue, called mesosperm^ 

 and the internal skin, or endosperm. The outer coat of the 

 seed is important, as the kernel, originally a fluid, could not 

 be formed without its presence. 



The Kernel^ or nucleus, includes all that is contained within 

 the spermoderm ; the kernel consists of the cdhuraen^ cotyledon.^ 

 and emhryo. The Albumen is the substance which, in many 

 seeds, is intermediate between the outer integument and the 

 embryo. It is thought to afford suj)port to the germinating 

 embryo plant, as does the white of an Qgg to the embryo bird. 



Both in respect to hardness and color, the albumen in many seeds greatly resem- 

 bles the white of a boiled egg. It \^ farinaceous, or mealy, consisting of cells filled 

 with starch, as in buckwheat, and horn-like in coffee. Tlje seeds of the pea and of 

 the cruciform plants are destitute of albumen. In some cases the embryo is in- 

 closed within a sac, called vitellus, corresponding to the yolk of an egg ; it is one of 

 the proper coats of the nucleus which has not been absorbed or converted into 

 albumen during the development of the seed. It is not considered an essential 

 part of the seed, because it is sometimes wanting ; but when present, it supports 

 and defends the embryo while imprisoned in the seed, and serves for nutriment 

 when it begins to germinate. Albumen makes up the chief part of some seeds, as 

 the grasses, corn, <fec. ; in the nutmeg, which has very small cotyledons, it is remark- 

 able for its variegated appearance and aromatic quality. It chiefly abounds in 

 plants which are furnished with but one cotyledon. 



Cotyledons (from liotide^ a cavity) are the thick lobes of seeds. 

 They are the first visible leaves ; often fleshy and spong}", of a 

 succulent and nourishing substance, which serves for the food 

 of the embryo at the moment of its germinating. 



Nature seems to have provided the cotyledons to nourish tJie plant 

 in its tender infancy. After seeing their young charge sufficiently vig- 

 orous to sustain life witliout their assistance, the cotyledons in most 

 plants wither and die. Fig. 116 represents the cotyledons of the bean, 

 as divested of the outer covering; a a represent the two cotyledons ; 

 b and c, the embryo ; d shows the petioles or stems of the cotyle- 

 dons. 



a. Parts of the seed — E3-e — Integuuient — The kernel, its parts — Albumen— Cotyledons. 



