Vegetable Physiology. 337 



the stem, just as when any leaf-bud (whose young leaves are 

 arranged in a series of whorls, one above or within another) is 

 elongated into a branch. On the other hand, in the Straw- 

 berry, the leaves, which are usually alternate, become oppo- 

 site, or whorled at intervals. It is to be remarked that, when 

 leaves are opposite, the several pairs are not in a line with one 

 another above and below, but each pair is at right angles to 

 the next ; so that, if the internode between two pairs were 

 undeveloped, a whorl of four leaves would be produced. 

 Again, when one whorl is developed near another, their leaves 

 do not issue from corresponding points in the stem, but are 

 arranged in such a manner that the leaves of one arise from 

 what seem to be the intervals of those of the other, so that the 

 whorls are alternate to each other. It is clearly shown that the 

 several parts of the flower are arranged exactly on the same 

 principles. 



It is by the developement of leaf-buds into branches bearing 

 leaves, and capable of producing flowers and fruit, that the 

 tree or plant is increased in size. The leaf-bud has also the 

 power of developing roots, if removed from the parent, and may 

 thus form a completely independent structure. It is by sepa- 

 rating the buds, and by placing these in circumstances favor- 

 able to their growth, that any particular variety of plant may 

 be propagated with more certainty than by seeds. As every 

 bud is thus capable of maintaining an independent existence, 

 it may be regarded as in some degree a distinct individual ; 

 and thus a tree would not be one being, but a collection of 

 many. This is in part true ; still it must be considered, that 

 while they all remain upon one stem, they depend upon it for 

 nourishment, and are liable to be influenced by the same cir- 

 cumstances which affect it. Still it is quite possible for some 

 buds to live while others die. Thus if arsenic be introduced 

 into any portion of the sap-wood, it will give such a poisonous 

 character to the fluid, that all the buds and branches above it 

 will be killed, while those below remain uninjured. It has 

 even occurred that a single bud at the summit of a stem has 

 preserved its life, while the vitality of all the others, and of the 

 stem, has been in some manner destroyed ; and that from this 

 hud have been sent down bundles of root-fibres between the 



