Note on the influence of extraneous forces upon the proportion of the sexes produced by canaries / by Walter Heape.

  • Heape, Walter, 1855-1929.
Date:
[1907]
Catalogue details

Licence: In copyright

Credit: Note on the influence of extraneous forces upon the proportion of the sexes produced by canaries / 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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    Ox tD \ [Extracted from the Proceedings of the CambridgefPhiloso'phical Society i Vol. XIV. Pt. II.] Note on the influeh^pf ^irmuivsfjf^cefupon the proportion of the sexes produced by Cgtharies. By Walter Heape, M.A., F.R.S., Trinity College, CambrM^. BMAy..-i 907.] The careful records on which the following note is based were very kindly supplied to me by two breeders of canaries, Mr Needham and Mr Gentry. Their results show a remarkable difference in the proportion of the sexes of the young birds produced in these two aviaries, which is consistent both in detail and in the totals. Such consistent variation, when considered in relation to the food supplied and to the temperature and surroundings to which the birds were subjected, may be interpreted as evidence of the exercise of extraneous forces on the proportion of the sexes pro- duced and of selective action on the generative elements dehisced by the parent birds. In a former paper (“Note on the proportion of the sexes in Dogs,” Proc. Gamb. Philosoph. Soc., 1907) I have indicated my reasons for believing that extraneous forces do influence the proportion of the sexes produced by certain animals, and the evidence now presented is, I judge, confirmatory of that view. In the following account Mr Needham’s records will be referred to as N, Mr Gentry’s as 0. Residts as shown in Table I. N. During the years 1888—1893,11 cocks and 22 hens were bred from. One cock and one hen were “ London Fancy ” breed, a second hen was cross bred, all the rest were “Lizard” canaries. These birds formed 71 nests and laid 313 eggs, from which 87 cocks and 113 hens were hatched—a total of 200 chicks. That is, with a loss of 36T7o the proportion of the sexes produced was at the rate of 76’99 cocks per 100 hens. G. During the year 1892 bred from 4 cocks and 8 hens, all of which were “ Lizards ” with the exception of one cross bred hen. These birds made 20 nests, laid 84 eggs from which 53 cocks and 15 hens, a total of 68 chicks, were hatched. That is, with a loss of 19’05°/^ of eggs the proportion of the sexes produced was at the rate of 353’3 cocks per 100 hens. But certain data are available where no loss of eggs occurred. N had 4 cocks and 9 hens making 11 nests and laying 48 eggs, all of which were hatched. These produced 22 cocks ind 26 hens, that is at the rate of 84’61 cocks per 100 hens. G had 4 cocks and 6 hens making 11 nests and laying 48 eggs, all of which were hatched. These produced 35 cocks and 13 hens, that is at the rate of 269‘23 cocks per 100 hens. Thus G’s birds hatched, and must have produced, a very large excess of cocks, while A’s birds are responsible for a marked excess of hens.