Theory of Propagation. 45 



respected kinds, as that the same method would succeed in the 

 case of plants. As we cannot perceive much resemblance in 

 he higher, let us examine the lower orders of animals, and see, 

 as the vital machine becomes less complicated, if such subdi- 

 visions ever produce any results to compare with those presented 

 by vegetables. We find that the Sponge, an acknowledged 

 animal, forms a bud on itself, which in time drops off and be- 

 comes a perfect animal, as will any portion that happens to be- 

 come separated. Our analogy, without proceeding farther, will 

 be concluded by instancing the Polypus, which can be divided 

 into as many animals as it contains atoms, which last phenome- 

 non we wish to bring distinctly before the mind, for, on a proper 

 understanding of it, our whole subject rests. A plant can be 

 advantageously viewed in the light of a vegetable Polypus, which 

 in truth the confervas are, to all intents and purposes, as their 

 buds and branches consist only of simple cells. Above this 

 rank, the embryo leaf is the real germ of the future plant ; the 

 base representing the root ; the middle portion, the first internode 

 of the stem; and the top, the future leaves and branches. The 

 well known fact, that leaf cuttings will strike root and grow, 

 confirms this view of the subject. Every one of these prismatic 

 atoms has the power of developing another like itself, which 

 springs from its top part ; this, by its ascending growth, as Gray 

 observes, forms the second joint of the stem and the blade of the 

 second leaf; while, by its descending growth, it can reach the 

 soil only by sending its woody tissues down through the first 

 joint to the same final termination in the root. This second one, 

 of course, according to the general law, forms another upon its 

 own summit, with its proper leaf; the wood which this gene- 

 rates passing downwardly, penetrating all the preceding atoms, 

 and at length reaching the soil in the same manner. Thus the 

 stem results from the evolution of one integral element after an- 

 other, each developed from, and implanted upon the summit of 

 its predecessor, and contributing by its wood to the increase of 

 the common trunk in diameter, and ultimately to the extension 

 of the roots. As might be expected from this, if marks are made 

 at certain distances on a root, you will find these distances are 

 not altered by growth ; but if you make similar marks on a stem 

 or branch, the distances will increase, showing that it grows its 

 whole extent ; this prevails in all exogenous plants. 



