THE SEED. 



cipally, as in wheat and the other cereal grains, sometimes as a 

 continuous, often dense, incrusting deposit, as in the cocoa-nut, the 

 date, the coffee-grain, &c. When it consists chiefly of starch- 

 grains, and may readily be broken down into a powder, it is 

 said to be farinaceous, or meaty, as in the cereal grains generally, 

 in buckwheat, &c. When a fixed oil is largely mixed with this, 

 it becomes oily, as in the seed of the Poppy, &c. ; when more 

 compact, but still capable of being readily cut with a knife, it is 

 fleshy, as in the Barberry, &c. ; when it chiefly consists of muci- 

 lage or vegetable jelly, as in the Morning Glory and the Mallow, it 

 is said to be mucilaginous; when dense and tough, so as to offer 

 considerable resistance to the knife, as in the Coffee, the Blue Co- 

 hosh (Leontice), &c., it is corneous, that is, of the texture of horn. 

 Between these all gradations occur. Commonly the albumen is a 

 uniform deposit. But in the nutmeg, and in the seeds of the Pa- 

 paw (Fig. 494) and of all plants of the Custard Apple Family, it 

 presents a wrinkled or variegated appearance, owing to numerous 

 transverse divisions, probably caused by inflections of the embryo 

 sac ; in these cases the albumen is said to be ruminated. 



628. As already intimated, the albumen may originate from 

 new tissue formed either within the embryo sac (579), which is 

 probably the more common case ; or in the nucleus of the ovule 

 exterior to the embryo sac, which is certainly the case in the 

 Water-Lily and its allies (the Water-shield, &c., Fig. 518), and in 

 Saururus, for here the thickened embryo sac persists within or at 

 one extremity of the copious albumen ; or both kinds may co- 

 exist. In the first-named case, if any of the proper tissue of the 

 nucleus remains, it is condensed and forms the inner integument of 

 the seed, or becomes confluent with it (623). 



629. The office to which the albumen is subservient is the nour- 

 ishment of the embryo when it begins to develope into a plant. It 

 is a store of nutritive matter, in a very compact or condensed 

 form, accumulated around or next the embryo, which feeds upon it 

 in germination, until it is so far developed that it can obtain and 

 assimilate food for itself (118). The name, therefore, which was 

 applied to it by Gartner, from its analogy to the albumen or white 

 of the egg of birds, is not inappropriate, although the comparison 

 will not bear to be carried out in detail. As would be expected 

 from its functions, the albumen is the more copious in the seed in 

 proportion as the embryo is smaller and feebler, or less developed. 

 (Fig. 456, compared with Fig. 461, &c.) 



