54 



COURSE OF THE SAP. 



PT. 11. 



an accidental shoot from the bare stem of a tree, a 

 regular bud is first formed ; and, consequently, even 

 these accidental shoots have symmetrical growth. But 

 a leaf is never formed by itself ; so that, in the case of 

 an accidental shoot from a bare stem, it may be said 

 that a bud is formed without a previous leaf, but a leaf 

 is never formed without a previous bud, as Liebig would 

 have it. 



When the heads of coppice-stools or of pollards 

 have been cut, their first year's growth is always late, 

 because they have first to form buds before they can 

 shoot. 



The tulip-tree is the most exquisite exemplification 

 of the parturition of a bud. If, between May and 

 August, the transparent case is held up to the light, 

 the enclosed leaf will be seen doubled on itself, and 

 crane-necked. The case is broken by the protrusion, 

 not of the leaf only, but of the whole shoot or contents 

 of the bud ; and the case, which remains for some time 

 at the foot of each leaf- stalk, is not that which con- 

 tained that leaf, but that which contained the embryoes 

 of all its younger brethren. These younger brethren, 

 which are beautifully packed nearer to the stem than 

 the head of the leaf which is to be developed, are succes- 

 sively protruded farther from the stem than that leaf 



There is nothing in which trees differ more than in 

 the folding of the leaf in the bud, though it is always 

 the same in the same species. Some plants, as the vine, 

 have each leaf beautifully folded over its batch of 



