Page:Popular Science Monthly Volume 43.djvu/234

222 occur in vast swarms, they can hardly fail to be highly effective agents in seed dissemination, thus repaying to some extent for the immense damage they often do.

Fishes are known to swallow seeds of many kinds, and must transport them from place to place; but the value of fishes as seed conveyers is hard to estimate.

We have just said that our edible fruits are really contrivances for securing seed dissemination, especially through the agency of birds. Take, for example, some of our common fruits—the currant, grape, plum, peach, apple, etc. All these are constructed with this end in view. When ripe, they are colored brightly to attract animals; some possess agreeable odors, and most have a delicious taste and consistence. In short, they are highly adapted to become the food of animals. While swallowing such food animals can hardly help swallowing seeds as well, and such seeds are finally emitted under conditions admirably conducive to germination. Why our most delicious fruits are often offset by their disagreeable seeds may have occurred to many of us. The fact is, by this means seeds are protected from possible injury in the alimentary canals of animals. Take, for example, the small, hard seeds of the grape or fig, and the similar so-called seeds of the strawberry, blackberry, and others. Far from being destroyed by the digestive juices, the seeds are probably facilitated in their germination by the warmth and moisture received.

The rapid ripening of fruits doubtless prevents their premature destruction. The accompanying change in color is remarkable. Whereas young fruits harmonize completely with surrounding color, mature fruits are extremely conspicuous. Recall the barberry, rose, sumach, mountain ash, and many more. In some honeysuckles each cluster of scarlet berries stands in violent contrast against a green leaf. In the blackberry lily of our gardens the sides of the pod roll back and display their white linings, conspicuously relieving the black, berry-like seeds. The burning-bush is a brilliant example with its flaming scarlet. In the West Indies is a plant whose pods are red within, containing seeds that are blue. Other instances might be named, but they are indefinitely numerous and easily observed by any one.

Many of our fruits are covered with a waxy "bloom" as it is called. This is plainly a protection, for it is commonly known that fruits will long resist decay provided this coating is uninjured. Its probable effect is to resist decomposition by moisture and fungi.

The edible portion, however, is of most interest to us, not only scientifically, but also in a practical way. How highly it is esteemed by some animals may be judged from the expense we often incur in buying fruits out of season.