84 SIR J. LUBBOCK—PHYTOBIOLOGICAL OBSERVATIONS. 
Lime are rhomboid and five-lobed; but it must be remembered 
that in the Sycamore the embryo occupies the whole seed, while 
in the Lime it is embedded in perisperm. 
The peculiar lobed form of the cotyledons of Zilia enables 
them, I would suggest, to lie conveniently in the globose seed. 
On the Form of the Leaf in the Tulip-Tree (Liriodendron). 
The leaves of the Tulip-Tree (Liriodendron) have long attracted 
attention from the peculiarity of their form. I am not aware 
that any attempt has been made to account for this, though 
Mr. Meehan has an interesting note on the stipules of Lirioden- 
dron in the ‘ Proceedings of the Academy of Natural Sciences of 
Philadelphia '*. “The premorse or cut-off appearance of the 
blade,” he says, “ results from the stipular portions being adnate 
with the stem-axis, instead of being wholly on the petiole as in 
Magnolia.” I confess I do not understand this, and am not even 
quite sure whether he himself regards it as an explanation ; since 
he subsequently says, “ It may be here noted that those who look 
only to Mr. Darwin’s principle of natural selection to account for 
the laws of form, might be troubled by such cases as these. It 
is scarcely conceivable that a square-edged leaf-blade, as we find 
it in Liriodendron, is of any special benefit to the species; yet if 
this form is the consequence of some other act, which is a benefit ; 
the selection principle may still hold good ” t. 
I infer from this that Mr. Meehan remains in doubt as to the 
cause of the very peculiar form presented by the leaf of this 
species. 
Mr. Newberry has recently contributed to the ‘ Bulletin of the 
Torrey Botanical Club ’ (Jan. 1887) a notice on the “Ancestors of 
the Tulip-tree ;” but the ancestral condition does not appear to 
throw any light on the question, nor is there any other existing 
species to which we can look for guidance. 
The leaves of the Tulip-tree are saddle-shaped, abruptly 
truncate at the end, or, in the words of Bentham and Hooker, 
“sinuato 4-loba.” I have often wondered what could be the 
purpose or the advantage to the tree of this remarkable shape. 
One idea which occurred to me was that the differences of form 
might enable insects to perceive the tree at some distance, just as 
the colours of flowers are an advantage in rendering them more 
* L. c. 1870, p. 114. | t L. c. 1870, p. 116. 
