XI 
THE SPECIAL COLOURS OF PLANTS 
305 
altogether unattractive, never having any soft, juicy pulp; 
while the edible seeds often bear such a small proportion 
to the hard, dry envelopes or appendages, that few animals 
would care to eat them. 
The Meaning of Nuts. 
There is, however, another class of fruits or seeds, usually 
termed nuts, in which there is a large amount of edible matter, 
often very agreeable to the taste, and especially attractive 
and nourishing to a large number of animals. But when 
eaten, the seed is destroyed and the existence of the species 
endangered. It is evident, therefore, that it is by a kind of 
accident that these nuts are eatable ; and that they are not 
intended to be eaten is shown by the special care nature seems 
to have taken to conceal or to protect them. AVe see that all 
our common nuts are green when on the tree, so as not easily 
to be distinguished from the leaves ; but when ripe they turn 
brown, so that when they fall on to the ground they are equally 
indistinguishable among the dead leaves and twigs, or on the 
brown earth. Then they are almost always protected by hard 
coverings, as in hazel-nuts, which are concealed by the enlarged 
leafy involucre, and in the large tropical brazil-nuts and cocoa- 
nuts by such a hard and tough case as to be safe from almost 
every animal. Others have an external bitter rind, as in the 
walnut; while in the chestnuts and beechnuts two or three 
fruits are enclosed in a prickly involucre. 
Notwithstanding all these precautions, nuts are largely 
devoured by mammalia and birds; but as they are chiefly 
the product of trees or shrubs of considerable longevity, 
and are generally produced in great profusion, the perpetua¬ 
tion of the species is not endangered. In some cases the 
devourers of nuts may aid in their dispersal, as they probably 
now and then swallow the seed whole, or not sufficiently 
crushed to prevent germination ; while squirrels have been 
observed to bury nuts, many of which are forgotten and 
afterwards grow in places they could not have otherwise 
reached . 1 Nuts, especially the larger kinds which are so 
well protected by their hard, nearly globular cases, have their 
dispersal facilitated by rolling down hill, and more especially 
1 Nature, vol. xv. p. 117. 
X 
