THE SPECIAL COLOURS OF PLAXTS 



gether unattractive, never having soft, juicy pulp : 



while the edible seeds ften bear such a small proportion 



to the hard, dry envelopes or appendages, that few animals 

 would care to eat them. 



2 ' Mi f -~ufe. 



There is, however, another class of fruits or seeds, usually 



] nuts, in which there is a large amount of edible matter, 



often very agreeable be the baste, and especially attractive 



and nourishing tc 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 



ait that these nuts are eatable : and that they are not 

 intended to be eaten is shown by the special care nature -t:H> 

 to have taken to conceal or to protect them. We see th 

 our common nuts ai 3 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 



. ogmshable 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 



involucre, and in the large tropical brazil-nuts and coec :.- 



j such a hard and tough ea se is ~ : 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 

 - .ire enclosed in a prickly involucre. 



: withstanding all these pre* otions, nuts re largely 

 by mammalia and birds : but as they are chiefly 

 the product :: trc r 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 



and then swallow the seed whole, or not sufficiently 



crushed to prevent germination : while squirrels have ' sen 



observed to bury nuts, many of which are forgotten and 



afterwards grow in places they could not have otherwise 



Nuts, -specially the larger kinds which are - 



well protected by their hard, nearly globular cases, have their 



dispersal facilitated by rolling down hill, and more especially 



- .' ' . vol. xv. p. 117. 



X 



