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Show 304 THE PRINCIPLES OF PART If. periods each of four years: this, however, may b.e accidental ; .at least I can detect nothing of the kind with man m the decenm~l table in the Registrar's Report for 1866. I may add ~hat certam mares and this holds O'OOd with certain cows and w1th women, tend to produce more of one sex than of the other; Mr. Wright of Yeldersley House, informs me that one of his Arab ~arcs, though put seven times to different horses, produced seven filhcs. Dogs.-During a period of twelve years, from 1857 to 1868, the births of a large number of greyhounds, throughout England, have been sent to the 'Field' newspaper; and I am again indebted to Mr. Tegetmeier for carefully tabulating the results. 'rhe recorded births have been 6878, consisting of 3605 males and 3273 fema~cs, that is, in the proportion of l10·1 males to 100 fem~les. 'Ihc crreatest fluctuations occurred in 1864, when the proportwn was as 95·3 males, and in 1867, as l16·3 males to 100 females. The .above average proportion of 110·1 to 100 is probably nearly correct m the case of the greyhound, but whether it would hold with other don;testicated breeds is in some degree doubtful. Mr. Cupples has enqmrcd from several great breeders of dogs, and finds that all without exception believe that females are produced in excess; he suggests that this belief may have arisen from females being less valued and the consequent disappointment producing a stronger impression on the mind. Bheep.-The sexes of sheep are not ascertained by agriculturists until several months after birth, at the period when the males arc castrated ; so that the following returns do not give the proportions at birth. Moreover, I find that several great breeders in Scotland, who annually raise some thousand sheep, are firmly convinced that a larger proportion of males than of females die during the first one or two years; therefore the proportion of males would be somewhat areater at birth than at the aO'e of castration. This is a remarkable ~oincidence with what occurs~ as we have seen, with mankind, and both cases probably depend on some common cause. I have received returns from four gentlemen in England who have bred lowland sheep, chiefly Leicesters, during the last ten or sixteen years ; they amount altogether to 8965 births, consisting of 4407 males and 4558 females; that is in the proportion of 96·7 males to 100 females. With respect to Cheviot and black-faced sheep bred in Scotland, I have received returns from six breeders, two of them on a large scale, chiefly for the years 1867-1869, but some of the returns extendin()' back to 1862. The total number recorded amounts to 50,68S, consisting of 25,071 males and 25,614 females, or in the proportion of 97·9 males to 100 females. If we take the :English and Scotch returns together, the total number amounts CUAP. VIIL SEXUAL SELECTION. 305 to 59,650, consisting of 29,478 males and 30,172 females, or as 97·7 to 100. So that with sheep at the age of castration the females are certainly in excess of the males ; but whether this would hold good at birth is doubtful, owing to the greater liability in the males to early death.41 Of Cattle I have received returns from nine gentlemen of 982 births, too few to be trusted; these consisted of 477 bull-calves and 505 cow-calves; i.e. in the proportion of 94·4 males to 100 females. 'l'he Rev. W. D. Fox informs me that in 1867 out of 34 calves born on a farm in Derbyshire only one was a bull. Mr. Harrison Weir writes to me that he has enquired from several breeders of Pigs, and most of them estimate the male to the female births as about 7 to 6. This same gentleman has bred Rabbits for many years, and has noticed that a far greater number of bucks are produced than does. Of mammalia in a state of nature I have been able to learn very little. In regard to the common rat, I have received conflicting statements. Mr. R. Elliot of Laighwood, informs me that a rat- catcher assured him that he had always found the males in great excess, even with the young in the nest. In consequence -of this, Mr. Elliot himself subsequently examined some hundred -old ones, and found the statement true. Mr. F. Buckland has bred a large number of white rats, and he also believes that the males greatly exceed the females. In regard to Moles, it is said that "the males are much more numerous than the females ;" 42 and as the catching of these animals is a special occupation, the statement may perhaps be trusted. Sir A. Smith, in describing an antelope of S. Africa 43 (Kobus ellipsiprymnus), remarks, that in the herds of this and other species, the males are few in number compared with the females: the natives believe that they are born in this proportion; others believe that the younger males are expelled from the herds, and Sir A. Smith says, that though he has himself never seen herds consisting of young males alone, others affirm that this does occur. It appears probable that 'the young males when expelled from the herd, would be likely to fall a prey to the many beasts of prey of the country. 41 I am much indebted to Mr. Cupples for having procured for me the above returns from Scotland, as well as some of the following returns on cattle. Mr. R. Elliot, of Laighwood, first called my attention to the premature deaths of the males,-a statement subsequently confirmed by Mr. Aitchison and others. To this latter gentleman, and to Mr. Payan, I owe my thanks for the larger returns on sheep. 42 Bell, 'History of British Quadrupeds,' p. 100. 43 'lllustrations of the Zoology of S. Africa,' 1849, pl. ~9. VOL. I. X |