I recently read an essay in which the writer is good enough to say that, owing to the work of Darwin, the fact that the differences which we see between organisms have been reached by a gradual evolution, is not now disputed. That, at any rate, seems to be a solid achievement. But he went on to declare that when we inquire by what method this evolution was brought about biologists can return no answer. That appears to me to be a most extraordinary perversion of the truth. The reason why the gradual evolution of the various kinds of organisms is not now disputed is that Darwin showed the method by which that evolution can and must be brought about. So far from "returning no answer," Darwin and succeeding generations of biologists do return a very full answer to the question, "By what method has organic evolution been brought about?" Our misleading writer proceeds as follows: "The Darwinian theory of natural selection acting on minute differences is generally considered nowadays to be inadequate, but no alternative theory has taken its place." This is an entirely erroneous statement. Though Darwin held that natural selection acted most widely and largely on minute differences, he did not suppose that its operation was confined to them, and he considered and gave importance to a number of other characteristics of organisms which have an important part in the process of organic evolution. The assertion that the theory of natural selection as left by Darwin "is now generally held to be inadequate" is fallacious. Darwin's conclusions on this matter are generally held to be essentially true. It is obvious that his argument is capable of further elaboration and development by additional knowledge, and always was regarded as being so by its author and by every other competent person. But that is a very different thing from holding Darwin's theory of natural selection to be "inadequate." It is adequate, because it furnishes the foundation on which we build, and it is so solid, complete and far-reaching that what has been added since Darwin's death is very small by comparison with his original structure.