BIRDS AND THEIR DAILY BREAD. 603 



sistence to innumerable flocks of birds in all parts of the world. But 

 it makes a great difference to the plant species whether a bird prefers a 

 fruit for its flesh or for its kernel. The yellow thrush and cherry-finch 

 are both fond of cherries — one for the sake of their juicy envelope, 

 the other for the piquant meat of the pits. In the latter case harm 

 comes to the plant ; in the former case good. The colored, fragrant, 

 sweet-tasting berries are there to be eaten, and that principally by 

 birds, while the seeds pass out undigested and with vitality unharmed, 

 but rid of their coverings, which would have to be consumed by de- 

 cay if not eaten, and thereby, in some cases, even better adapted for 

 planting and growing than before. 



The birds in this way contribute much to the distribution of plants. 

 For the appetizing reward which they enjoy, they afford the species, 

 if not the single tree or plant, the most important service ; and when 

 we say that this bird damages the cherries and that one the grapes, we 

 speak from a selfish point of view that which is fundamentally false, 

 for the birds are ultimately useful to the plants. The Smyrneans call 

 the rose-starling the devil's bird when it visits their fruit-trees in July, 

 and forget that they welcomed the same bird as a saint when it cleared 

 away the locusts in May. 



Swallowed seeds undergo a superficial change in their passage 

 through the digestive apparatus, which is, however, not detrimental, 

 but rather, like the maceration which the gardener gives to his seeds, 

 only favorable to their vegetation. Acorns which the nut-hatch has 

 macerated in its crop, when dropped, are much surer to grow than 

 those which the forester plants. Some plants are absolutely depend- 

 ent on birds for their diffusion, and a kind of mutualism exists be- 

 tween the two — one of those remarkable phenomena in which very 

 different kinds of beings are reciprocally advantageous and adapted 

 to one another. A curious example of such adaptation is seen in the 

 case of the mistletoe and the mistle-thrush. The mistletoe, a parasite 

 of trees, is green and evergreen, though few other parasitic plants are 

 so colored ; and the color does not perform the same office to the mis- 

 tletoe as the green of other plants, for this plant derives its nourish- 

 ment directly from the sap of the tree on which it is growing without 

 the help of chlorophyl. But it has its uses, one of the chief of which 

 is to attract the thrush to itself. Its fruit-bearing time is when the 

 host-tree has shed its leaves, and it, being all upon the trunk that is 

 green, is conspicuous. Its fruit, a berry, inclosing the seeds in a 

 tough, adhesive envelope, is eagerly sought by the thrush, which can 

 recognize it from a distance by means of the sign it throws out. The 

 seeds hang by their sticky gum to the bird's bill after the fruit has 

 been eaten, and the bird, to remove the nuisance, is obliged to rub its 

 bill against the bark of the tree. This enables the seeds to plant 

 themselves in the crevices of the bark, which afford just the soil they 

 need to sprout and grow in. 



