254 SIR J. LUBBOCK ON THE FRUIT OF THE JUGLANDE X. 
transport. Moreover, for such large fruits wings would perhaps 
be scarcely adequate. 
In Pterocarya, on the contrary, the fruits are much smaller 
and wings therefore more suitable. Possessing in themselves 
the means of dispersal, they have no need of offering any 
attraction to animals. In fact every one which is eaten is so 
much pure loss. Hence, while the shell of the Walnut is 
sufficiently hard to protect the seed from the severity of the 
weather, and from the attacks of most insects &e., which would 
not help in their dispersal, it offers no obstacle to larger animals, 
That of Pterocarya, on the contrary, is very hard and strong, and 
even the interior portion (the walls and pillars surrounding the 
four hollows) are of the same character, while in the Walnut 
they are, comparatively, quite soft. 
One reason why the similarity of construction in the two seeds 
does not at first strike the observer, is that in Pterocarya the 
lobes of the seed evidently enter the pericarp; in Juglans, on the 
contrary, the lobes are so much larger that it rather seems as if 
_ the pericarp sent projections into the seed. 
That the present condition of the Walnut seedling is not 
original, we have interesting evidence in the presence of small 
leaves reduced to minute scales, as in the Oak and many other 
plants (Journ. Linn. Soe. Bot., vol. xxii. p. 360) with sub- 
terranean cotyledons. 
These scales evidently indicate the former presence of actual 
leaves, which are now no longer required. The curious lobings 
and foldings of the seed in the Walnut also remind us of the 
time when the cotyledons were variously lobed and folded so as 
to occupy the whole space in the gradually enlarging seed.. At 
present they seem to fulfil no useful function, except as a store- 
house of nourishment for the seedling. 
