SIR J. LUBBOCK—PHYTOBIOLOGICAL OBSERVATIONS. 85 
conspicuous. I then looked closely to see whether the peculiar 
forms could in any way be explained by the position of the leaves 
on the tree. I believe, however, that the cause is of a different 
nature, and has reference to the peculiar character of the bud. 
Each young leaf is, as in the Magnoliew generally, originally 
enclosed in, and sheltered by, the stipules of its predecessor. 
These are in Liriodendron oval, or in form resembling a shallow 
dish or spoon, so that, when placed face to face, they form a hollow 
almond-shaped body. The first of these neat little boxes which I 
opened showed the young leaf in the stage shown in fig. 171, p 
being the petiole, / the lamina of the leaf, and s that of the 
stipules. This threw me off the scent, as it seemed to afford no 
clue whatever to the peculiar form of the leaf. Eventually, how- 
ever, on examining younger buds, I found what I believe to be 
the true explanation. Within the stipules of such a bud as that 
represented in fig. 171 are contained several younger buds, one 
within the other. The youngest stage which need here be men- 
tioned is represented in fig. 172. The petiole is short and thick, 
the lamina is widest in the middle, and tapers regularly towards 
both base and apex; the stipules arein the form of a hemisphere. 
Gradually the stipules become more oval (fig. 173), assuming an 
almond-like form, somewhat thickest in the middle, tapering 
away to the sides, and more gradually towards the apex. The 
petiole has also elongated, and the lamina of the leaf is more ab- 
ruptly turned downwards; so that the petiole passes up one side 
of the stipule, while the midrib passes round the tip of the sti- 
pule and down again the other side. The lamina itself has con- 
siderably enlarged, is conduplicate or folded on itself, lies on one 
side of the stipule, between its own stipule and one of those by 
which it is enclosed. It has also considerably modified its form, 
and for the following reason. The young stipule at its central 
part touches the surrounding older stipule, so that the young leaf 
cannot find room between them ; while, on the other hand, at the 
sides and towards the end of the young stipule there is plenty of 
space for growth. This, I would suggest, accounts for the peculiar 
shape itassumes. Suppose, for instance, we lay an almond: on a 
table and place a piece of glass over it, the glass will touch the 
almond on a surface a (fig. 175). In the case of Liriodendron, 
from the form of the bud the surface of contact occupies not 
only the oval (a), but also tbe space lying below the line 6. 
The young leaf therefore, which I have indicated in fig. 173 by 
