"Look closely at the leaves," said the Doctor, "and perhaps you will find them."
"I've looked at every leaf," Fred answered; "but there is no butterfly to be seen."
"I've found one," said Frank, as he took what appeared to be a leaf between his thumb and forefinger.
LEAF BUTTERFLY IN FLIGHT AND REPOSE.
Sure enough, he had secured his prize, and then he pointed to another, which Fred immediately captured. Then the Doctor explained that they had found the famous Leaf Butterfly of Borneo, that has the peculiarity of resembling almost to perfection a dead leaf of the tree he inhabits. "You observe," said he, "that his two sets of wings have a dark line running along them from point to point that exactly resembles the midrib of a leaf, and there are lines running out from this centre that correspond to its veins. When the wings are folded, the lower end of them imitates the stem, and touches the twig when the butterfly is at rest; and their upper extremity is pointed in exact imitation of the point of the leaf. It is the habit of this butterfly to settle where there are several dead or partly withered leaves, and you must have very sharp eyes to distinguish him from one of them."
While the Doctor was talking the boys observed that their specimens were not exactly alike, and they called his attention to their discovery. The latter explained that it was difficult to find an exact resemblance in a dozen or more specimens, and they appeared to vary about as the leaves themselves were varied. It was a provision of nature for the protection and preservation of the butterfly, as he was enabled to escape many of his enemies by adapting his appearance to his retreat.
"I suppose," said one of the boys, "it is on the same principle that rabbits in our own country are brown in summer and white in winter. Many a bunny has saved himself from the hunters by changing from brown to white when the snow falls."