The following observation may serve to give an idea how small is the number of existing or durable forms compared with the number of forms incapable of existence. We have mentioned the fact observed by Moenkhouse, the writer, and Newman, that it is possible to fertilize the eggs of each marine bony fish with the sperm of practically every other marine bony fish. The number of teleosts at present in existence is about ten thousand. If we accomplish all possible hybridizations, one hundred million different crosses will result. Of these only a small fraction of one per cent. can live (see Chapter I), and it is generally the lack of a proper circulation which inhibits them from reaching maturity. It is, therefore, no exaggeration to state that the number of species existing today is only an extremely small fraction of those which can and possibly do originate, but which escape our notice and disappear because they cannot live or reproduce. If we consider these facts we realize that the mere laws of chance are adequate to account for the fact of the apparently purposeful adaptations; as they are adequate to account for the Mendelian numbers. CHAPTER XIII EVOLUTION Darwin’s work has been compared to that of Copernicus and Galileo inasmuch as all these men freed the mind from the incubus of Aristotelian philosophy which, with the efficient co-operation of the church and the predatory system of economics, caused the stagnation, squalor, immorality, and misery of the Middle Ages. Copernicus and Galileo were the first to deliver the intellect from the idea of a universe created for the purpose of man; and Darwin rendered a similar service by his insistence that accidental and not purposeful variations gave rise to the variety of organisms. In this struggle for intellectual freedom the names of Huxley and Haeckel must be gratefully remembered, since without them Darwin’s idea would not have conquered humanity. Darwin assumed that the small fluctuating variations could accumulate to larger variations and thus cause new forms to originate.