Wallace, from whom many of these illustrations are taken, says that to many persons it will seem impossible that such beautiful and detailed adaptations and resemblances—and these are only samples of thousands that occur in all parts of the world—can have been brought about by the preservation of fortuitous useful variations. Yet this will not seem so surprising, continues Wallace, if we keep in mind the facts of the rapid multiplication of animals, the severe struggle for existence, and the constant variability of these and all other organisms; and, further, that we must remember that these delicate adjustments are the result of a process, Natural Selection, which has been going on for millions of years, and that we now see the small percentage of successes among the myriads of failures. “From the very first appearance of insects, for instance, and their various kinds of enemies, the need for protection arose and was usually most easily met by modifications of color. Hence we may be sure that the earliest leaf-eating insects acquired a green color as one of the necessities of their existence; and, as the species became modified and specialized, those feeding on particular species of plants would rapidly acquire the peculiar tints and markings best adapted to conceal them upon those plants. Then, every little variation that, once in a hundred years perhaps, led to the preservation of some insect which was thereby rather better concealed than its fellows, would form the starting-point of a further development, leading ultimately to that perfection of imitation in details which now astonishes us.” So it is with the beautiful color adaptation of birds, mammals, lizards, and other animals. There is a lizard (_Phrynocephalus mystaceus_) inhabiting certain sandy districts in Asia, whose body is protectively colored and some of whose mouth-parts have alluring coloration and form. The general surface harmonizes with the sand in which it is found, while the skin at each angle of its mouth is of red color and so folded as to closely resemble a little red flower which grows in the sand. The lizard, being thus in harmony with its surroundings, resembling the sand and the flowers, is hidden from its enemies, the reptile-eating creatures. But at the same time insects, being attracted by what they take to be flowers, approach the lizards and are thus captured, being allured to their destruction. [Illustration: PLATE V.—A spider (_Misumena vatia_) lurking for prey on the center of a flower (_Coreopsis_). Illustrating especially alluring Coloration (for attracting prey), but also Protective Resemblance (against enemies). Reproduced from “American Spiders.” By courtesy of Rev. Henry C. McCook.]