Page:Insects - Their Ways and Means of Living.djvu/39

 liberates itself from the shriveled remnant of its hatching skin, and becomes a free new creature in the world. Being a grasshopper, it proceeds to jump, and with its first efforts clears a distance of four or five inches, something like fifteen or twenty times the length of its own body. When the young locusts hatch under normal undisturbed conditions, however, we must picture them as coming out of the eggs into the cavernous spaces of the egg pod, and all buried in the earth. They are by no means yet free creatures, and they can gain their liberty only by burrowing upward until they come out at the surface of the ground. Of course, they are not very far beneath the surface, and most of the way will be through the easily penetrated walls of the cells of the egg covering. But above the latter is a thin layer of soil which may be hard-packed after the winter's rains, and breaking through this layer can not ordinarily be an easy task. Not many entomologists have closely watched the newly-hatched grasshopper emerge from the earth, but Fabre has studied them under artificial conditions, covered with soil in a glass tube. He tells of the arduous efforts the tiny creatures make, pressing their delicate bodies upward through the earth by means of their straightened hind legs, while the vesicles on the back of the neck alternately contract and expand to widen the passage above. All this, Fabre says, is done before the hatching skin is shed, and it is only after the surface is reached and the insect has attained the freedom of the upper world that the inclosing membrane is cast off and the limbs are unencumbered.

The things that insects do and the ways in which they do them are always interesting as mere facts, but how much wiser might we be if we could discover why they do them! Consider the young locust buried in the earth, for example, scarcely yet more than an embryo. How does it know that it is not destined to live here in this dark cavity in which it first finds itself? What force activates the mechanism that propels it through the earth? And finally,