Few opponents of Darwinism could give a more pessimistic account of the accomplishments of the theory of natural selection than this, by one of the leaders of the modern school: “Discouraging, therefore, as it may be that the control of nature in her minutest details is here gainsaid us, yet it were equivalent to sacrificing the gold to the dross, if simply from our inability to follow out the details of the individual case we should renounce altogether the principle of selection, or should proclaim it as only subsidiary, on the ground that we believe the protective coloring of the butterfly is not a protective coloring, but a combination of colors inevitably resulting from internal causes. The protective coloring remains a protective coloring whether at the time in question it is or is not necessary for the species; and it arose as protective coloring—arose not because it was a constitutional necessity of the animal’s organism that here a red and there a white, black, or yellow spot should be produced, but because it was advantageous, because it was necessary for the animal. There is only one explanation possible for such patent adaptations, and that is selection. What is more, no other natural way of their originating is conceivable, for we have no right to assume teleological forces in the domain of natural phenomena.” Weismann states that he does not accept Eimers’s view that the markings of the wings of the butterflies of the genus Papilio are due to a process of evolution in a direct line, independent of external causes. “On the contrary, I believe it can be clearly proved that the wing of the butterfly is a tablet on which Nature has inscribed everything she has deemed advantageous to the preservation and welfare of her creatures, and nothing else; or, to abandon the simile, that these color patterns have not proceeded from inward evolutional forces but are the result of selection. At least in all places where we do understand their biological significance these patterns are constituted and distributed over the wing exactly as utility would require.” Again: “I should be far from maintaining that the markings arose unconformably to law. Here, as elsewhere, the dominance of law is certain. But I take it, that the laws involved, that is, the physiological conditions of the variation, here are without exception subservient to the ends of a higher power—utility; and that it is utility primarily that determines the kind of colors, spots, streaks, and bands that shall originate, as also their place and mode of disposition. The laws come into consideration only to the extent of conditioning the quality of the constructive materials—the variations, out of which selection fashions the designs in question. And this also is subject to important restrictions, as will appear in the sequel.” This conclusion contains all that the most ardent Darwinian could ask. He rejects the idea that internal laws alone could have produced the result, because:—