344 



ORGANOGRAPHY. 



times it is more or less separated into distinct compartments 

 by the folding inwards of the endopleura as already described, 

 (See p. 340); in such cases, the albumen is said to he ruminated, 

 as in the Nutmeg, Betel-nut (Jig. 740, p), 

 Papaw, &c. 



b. The Embryo is the rudimentary plant, 

 and is present in all true seeds. The presence 

 of a true embryo is the essential character- 

 istic of the seed of flowering plants; for a 

 spore, as the reproductive body of a flower- 

 less plant is called, has no true embryo, the 

 rudimentary plant being only developed from 

 it after its separation from the parent. The 

 embryo being the rudimentary plant it is 

 necessarily the most important part of the 

 seed, and it contains within it, in an unde- 

 veloped state, all the essential parts of which 

 a plant is ultimately composed. Thus we 

 distinguish three parts in the embryo, coi*re- 

 sponding to the root, stem, and leaves of the 

 perfect plant; namely, a radicle, plumule or 

 yemmule, and one or more cotyledons. These 

 parts maybe readily recognised in many seeds; thus in the 

 embryo of the Lime {fig. 741), the lower portion, r, is the radicle 

 or portion from which tlie root is developed ; 

 the two expanded lobed bodies above, c, c, 

 are the cotyledons, and between these, the 

 plumule or rudimentary stem is placed. In 

 the Pea, again {fig. 1 60), the two fleshy lobes, 

 c, c, are the cotyledons, between which there is 

 situated a little bud-like process, the upper 

 part of which is the plumule, w, and the lower 

 part, r, the radicle. These parts are still 

 better observed when the embryo has begun 

 to develop in the process of germination ; 

 tlius in figure 161, which represents the 

 French Bean in that condition, r is the ra- 

 dicle from which the roots arc being given 

 off, the cotyledons are marked c, c, and the 

 plumule is seen coming oft" from between the cotyledons, and 

 forming a direct continuation of the axis from which the 

 root is developed below. By some botanists, the ])oint of 

 union of the base of the plumule with the radicle and co- 

 tyledons, is called tlie caulicule or tigelle ; this is generally a 

 mere point, but at other times it forms a short stalk (figs. 161 

 and 725, t). Phmts which thus possess two cotyledons in their 

 embryo, arc called J)icofyledonous. But there is anotlicr class of 

 plants in which there is commonly but one cotyledon present 



Fig. 7i0. Vertical sec- 

 tion of the fruit of 

 Areca Catechu, c. 

 periantli. /• Pe- 

 ricarp. J). Rumi- 

 nated albumen, e. 

 Embryo. 



Fig. 741. 



Fi{f. 741. Embr3'0 of 

 tiie Lime-tree (7'i- 

 h'u). c. Cotyledons, 

 with five lobes ar- 

 ranged in a palmate 

 manner, r. Kadicie. 



