OCR Text |
Show -300 'l'IIE PRINCIPLES OF PART II. In the following chapters, I shall treat of the secondary sexual character~.; in animals of all classes, and shall endeavour in each case to apply the principles explained in the present chapter. The lowest classes will detain us for a Yery short time, but the higher animals, especially birds, must be treated at ·considerable length. It should be borne in mind that for reasons already assigned, I intend to give only a few illustrative instances of the innumerable structures by the aid of which the male finds the female, or, when found, holds her. On the other hand, all structures and instin(:ts by which the male conquers other males, and by which he allures or excites the female, will be fully discussed, as these are in many ways the most interesting. .Supplement on the proportional numbm·s of the two sexes , in animals belonging to various classes. . As no one, as. far as I can discover, has paid attention to the. relatr~'e numbers of the two sexes through ·out the ammal kmgdom, I will here give such materials as I hav~ been able to collect, although they are extremely 1mperfect. They consist in only a few instances of actual enumeration,. and the numbers are not very large. As th~ proportiOns are known with certainty on a large scale m the case of man alone, I will first give them, as a standard of comparison. Man.-In England duriug ten years (from 1857 to 1866) 707,12? c~ildren on an annual average. have been born ahve, 111 the proportion of 104·5· males to 100 females. But in 1857 the male births through- out England were as 105·2, and in 1865 as 104·0 to 100. Looking to separate districts, in Buckinghamshire (where on an average 5000 children are annually born) Cu.AP. VIII. SEXUAL SELECTION. 301 the mean proportion of male to female births, during· the whole period of the above ten years, was as 102·8 to 100; whilst inN. vVales (where the average annual births are 12,873) it was as high as 106·2 to 100. Taking a still smaller district, viz., Rutlandshire (where· the annual births average only 739), in 1864 the male births were as 114·6, and in 1862 as 97·0 to 100; but even in this small district the average of the 7385- births during the whole ten years was as 104·5 to 100; that is in the same ratio as throughout England.3'l The proportions are sometimes slightly disturbed by unknown causes; thus Prof. Faye states "that in " some distrjcts of Norway there has been during a " decennial period a steady deficiency of boys, whilst "in others the opposite condition has existed." In France during forty-four years the male to the female births have been as 106·2 to 100; but during this period it has occurred five times in one department,. and six times in another, that the female births have exceeded the males. In Russia the average proportion is as high as 108·9 to 100.33 It is a singular fact that with Jews the proportion of male bjrths is decidedly larger than with Christians : thus in Prussia the proportion is as 113, in Breslau as 114, and in Livonia as 120· to 100; the Christian births in these countries being the same as usual, for instance, in Livonia as 104 to· 100.34 It is a still more singular fact that in different. natjons, under different conditions and climates, in N a pies, Prussia, \Vestphalia, France and England, the a2 • Twenty-ninth Annual Report of the Registrar-General for 1866.' In tLi:l report (p. xii) a special decennial table is given. 33 For Norway and Russia, see abstract of Prof. Faye's researches, in 'British and Foreign l\1edico-Chimrg. Review,' April, 1867, p. 343,.. 345. For France, the 'Annuaire pour l'An 1867,' p. 21 ~t 34 In regard to the Jews, seeM. Thury, 'La Loi de Production des Sexes,' 186:3, p. 25. |