Chap. TL] 
COURSE OF THE SAP. 
C>3 
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 pol¬ 
lards 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 exempli¬ 
fication 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 
contained 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 successively 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 younger brethren. It 
