24 Evolution and Adaptation 
In regard to the colors of plants, there are many cases of 
brilliant coloration, which so far as we can see can be of no 
service to the organism. In such forms as the lichens and 
the toadstools, many of which are brilliantly colored, it is 
very doubtful if the color, as such, is of any use to the plant. 
The splendid coloring of the leaves in the autumn is certainly 
of no service to the trees. 
It should not pass unnoticed in this connection that the 
stems and the trunks of shrubs and of trees and also many 
kinds of fruits and nuts are sometimes highly colored. It 
is true that some of the latter have been supposed to owe 
their color to its usefulness in attracting birds and other 
animals which, feeding on the fruit, swallow the seeds, and 
these, passing through the digestive tract and falling to the 
ground, may germinate. The dissemination of the seeds of 
such plants is supposed to be brought about in this way; and 
since they may be widely disseminated it may be supposed 
that it is an advantage to the plant to have attracted the 
attention of the fruit-eating birds. On the other hand one 
of the most brilliantly colored seeds, the acorn, is too large 
to pass through the digestive tracts of birds, and is, in fact, 
ground to pieces in the gizzard, and in the case of several 
mammals that feed on the acorns, the acorn is crushed by 
the teeth. It would seem, therefore, that its coloration is 
injurious to it rather than the reverse, as it leads to its 
destruction. It has been suggested by Darwin that since 
the acorns are for a time stored up in the crop of the 
bird, the passenger pigeon for example, and since the birds 
may be caught by hawks and killed, the seeds in the crop 
thus become scattered. Consequently it may be, after all, 
of use to the oak to produce colored acorns that attract the 
attention of these pigeons. This suggestion seems too far- 
fetched to consider seriously. In the case of the horse- 
chestnut the rich brown color is equally conspicuous, but 
the nut is too large to be swallowed by any of the ordinary 
