The proportion of the sexes produced by whites and coloured peoples in Cuba : [abstract] / by Walter Heape.

  • Heape, Walter, 1855-1929.
Date:
[1909]
Catalogue details

Licence: In copyright

Credit: The proportion of the sexes produced by whites and coloured peoples in Cuba : [abstract] / by Walter Heape. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    '& L.Reprinted from ^Proceedings of Tflfe. Royal Society, B. Vol. 81] -4 OCT 09 The Proportion oj\tl^ Setter produced by Whites and Coloured Cuba. By Walter Heape, M.A., F.R.S., Trinity College, Cambridge. (Received September 30,—Read November 26, 1908.) (Abstract.) Introduction.—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 of the sexes but remarks on the fact that this 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 Diising, 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. Students of heredity in those days claimed that the laws of heredity were sufficient to account for all inequalities, but Diising emphatically denied this, and in my opinion satisfactorily showed he had sound reason for doing so. During the last few years much work has been done on sex, especially regarding the factors which determine sex, and strong evidence has been brought to show that both individual spermatozoa and ova are themselves of definite sexuality. It is suggested that the sex of the individual resulting from the conjugation of a spermatozoan and an ovum must be determined by one or other of them, not by both, and it is claimed that, in order to fulfil the conditions, a M. ovum must be fertilised by a F. spermatozoan and, vice versd, a F. ovum by a M. spermatozoan. So far as the evidence available now goes, it would seem possible that in some animals the sex of the offspring is determined by the spermatozoan and in other animals by the ovum. The facts are not clear, however, though it is to be hoped the efforts now being made by b