DEVELOPMENT OF THE EMBRYO. 79 



root, and an Ascending Axis or stem. The point of union or base 

 of the two is termed the crown, neck, or collar. Both the root and 

 stem branch ; but the branches are repetitions of the axis from 

 which they spring, and obey its laws. The branches of the root 

 tend to descend ; those of the stem tend to ascend. 



114. Organs of Vegetation, These three organs, Stem, Root, and 

 Leaves, either preexist rudimentarily in the seed, or appear at the 

 first development of the embryo in germination. Of , them, vege- 

 tables essentially consist ; for they are all that are requisite to, and 

 actually concerned in, their life and growth. Indeed, the whole ul- 

 terior evolution of the plant exhibits only repetitions of these essen- 

 tial parts, under more or less varied forms. They are, therefore, 

 properly termed the FUNDAMENTAL ORGANS of plants, or the OR- 

 GANS OF VEGETATION. The root absorbs the crude food of the 

 plant from the soil ; this is conducted through the stem into the 

 leaves, is in them digested, under the agency of solar light and 

 heat ; and the nourishment thus assimilated is returned into the 

 stem and root, to be expended in the formation of new rootlets, 

 new branches, and new leaves. The more the plant grows, there- 

 fore, the more it multiplies its instruments and means of growth ; 

 and its evolution would seem to be limited only by the failure of 

 food, of a fit temperature, or other external circumstances. 



115. Sooner or later, however, the plant changes its mode of 

 development, and bears Flowers, or ORGANS OF REPRODUCTION. 

 But even in these, the philosophical botanist recognizes the stem 

 and leaves, under peculiar forms, adapted to special purposes. 

 And the object and consummation of the flower is the production 

 of seeds, containing an embryo plant which is composed of these 

 same fundamental organs, and which in its development repeats 

 these successive steps, to attain the same ultimate result. 



116. Having briefly traced the plan and progress of vegetation 

 from the simplest or lowest through to the highest or most elabo- 

 rately perfect grade of plants, we may, in the following chapters, 

 leave the Cryptogamous or Flowerless plants entirely out of view 

 (reverting to them only to explain separately the peculiarities of 

 their different orders at the close), and explain the phenomena, 

 first of vegetation, and then of reproduction, as manifested in the 

 higher series of Phsenogamous or Flowering plants. The simpler 

 kinds of the lower series doubtless afford remarkable facilities for 

 investigating questions of anatomical structure, and for ascertaining 



