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 



