MORPHOLOGY OF THE FRUIT AND SEED 271 



(fig. 591), or in both endosperm and perisperm, as in NyiiipliiBa 

 (fig. 588). We have two parts, therefore, to describe as consti- 

 tuents of the liernel, namely, the embryo and the albumen, the 

 latter being composed of endosperm or perisperm, or both. 



a. Alhumcn, Endosperm, Perisperm. — Those seeds which 

 have the embryo surrounded by albumen, that is, by either endo- 

 sperm or perisperm, or both, are said to be albuminous ; while 

 those from which it is absent are exalbuminous. The amount 

 of albumen will in aU cases, as described above, be necessarily in 

 inverse proportion to the size of the embryo. 



The cells of the albumen contain various substances, such 

 as starch, albuminoids, oily matters, &c., and thus act as 

 reservoirs of nutriment for the use of the 

 embryo during the process of germination. 

 The varying contents of the cells, together 

 with certain differences in the consistence 

 of their walls, cause the albumen to assume 

 different appetirances in ripe seeds, and thus 

 frequently to afford good characteristic 

 marks of different seeds. Thus, the albmxien 

 is described as mealy, starchy, or farina- 

 ceous, when its cells are filled with starch- 

 granules, as in the Oat and other Cereal 

 grains ; it is said to be fleshy, as in the 

 Barberry and Heartsease, when its walls 

 are soft and thick ; when its cells contain 

 oil-globules, as in the Poppy and Cocoa- 

 nut, it is oily ; when the cells are soft, 

 and chiefly formed of mucilage, as in the 

 Mallow, it is inucilaginovs ; and when the 

 cells are thickened by layers of a hardened nature, so that 

 they become of a horny consistence, as in the seeds of the 

 Vegetable Ivory Palm and Coffee plant, the albumen is de- 

 scribed as horny. These different kinds of albumen are fre- 

 quently more or less modified in difterent seeds by the admixture 

 of one with the other. 



Generally speaking, the albumen presents a uniform appear- 

 ance throughout, as in the si eds of the Vegetable Ivory Palm ; 

 but at other times it is more or less separated into distinct com- 

 partments by the folding inwards of the tegmen as already 

 described. In the latter case the albumen is said to be ruminated, 

 as in the Nutmeg and Betel-nut (fig. 589, jo). 



b. The Embryo is the rudimentary plant, and is therefore 



Fit/. 688. Vertical 

 section of the seed 

 of the White Wa- 

 ter-lily, .showing 

 the embryo en- 

 clojed in the "re- 

 mains of the em- 

 bryo-sac, and on 

 the outside of this 

 the perisperm sur- 

 rounded by the 

 integument?. 



