The proportion of the sexes produced by whites and coloured peoples in Cuba

.—Darwin, in his great work on the Descent of Man, deals with the proportion of the sexes in various animals and the power of natural selection to regulate the proportional number of the sexes. He recognises a general tendency to equality is often greatly disturbed. In certain rare cases of marked inequality he concludes they might have been acquired through natural selection, but in all ordinary cases, such as, for instance, the difference in the proportion of the sexes in legitimate and illegitimate children, it can hardly be so accounted for and must be attributed to unknown conditions, although, he adds, natural selection will always tend to equalise the relative number of the two sexes. About that time a host of writers were engaged in investigating various possible causes for this inequality, and many theories were promulgated to account for it, such as the relative age of the parents, the time of conception, and so forth. Prominent amongst them was Düsing, who set himself to show that nutriment was the chief determining factor. He set forth his case with great ability and brought an enormous mass of evidence in support of his view.