Nature’s examination, like that held for entrance to the Indian Civil Service, is a liberal one, so that the qualifications of the successful candidates vary considerably. Provided a candidate is able to gain more marks than the other candidates for a vacancy, it matters not in what subjects the marks are gained. So is it in nature. Natural selection takes an organism as a whole. One species may have established itself because of its fleetness, a second because of its courage, a third because it has a strong constitution, a fourth because it is protectively coloured, a fifth because it has good digestive powers, and so on. We thus perceive the part played by natural selection and other forms of isolation in the making of species. It is obvious that these do not make species any more than the Civil Service Commissioners manufacture Indian civil servants. The real makers of species are the inherent properties of protoplasm and the laws of variation and heredity. These determine the nature of the organism; natural selection and the like factors merely decide for each particular organism whether it shall survive and give rise to a species. The way in which natural selection does its work is comparatively easy to understand. But this is only the fringe of the territory which we call evolution. We seem to be tolerably near a solution of the problem of the causes of the _survival_ of any particular mutation. This, however, is merely a side issue. The real problem is the cause of variations and mutations, or, in other words, how species _originate_. At present our knowledge of the causes of variation and mutation is practically _nil_. We do not even know along what particular lines mutations occur. We have yet to discover whether one mutation invariably leads to another along the same lines—in other words, whether mutating organisms behave as though they had behind them a force acting in a definite direction. The solution of these problems seems afar off. The hope of solving them lies, not in the speculations in which biologists of to-day are so fond of indulging, but in observation and experiment, especially the last. The future of biology is largely in the hands of the practical breeder. FOOTNOTES [1]The white, pied, and “Japan” individuals are not more different from the type than some variations occurring in wild birds. [2]This short-legged type of dog is sometimes seen among the ownerless and unselected pariah dogs of Indian towns; and a short-legged variety of the fowl may occur sporadically in Zanzibar, where the long-legged Malay is the prevalent breed. [3]“Effected” appears in the earlier editions, but in the later editions has given place to “affected,” probably a printer’s error.