INFLUENCE OF A PREVIOUS IMPREGNATION. 273 



having once given birth to offspring having a strong- 

 ly-marked character, becomes in a degree moulded to 

 that character, and tends again to produce it. 



" At all events the teaching of this fact is plain, 

 and we would never, on any account, allow any valued 

 hens to mate with another breed. We have known 

 ourselves several cases in which hens once crossed have 

 reproduced strong cases of that cross two years after- 

 ward ; and many otherwise unaccountable occurrences, 

 which have given rise to bitter recriminations, may be 

 thus very easily explained." x 



The intensity of the influence of the male element 

 of fertilization upon the ova seems to vary widely in 

 different species of animals. In many species a single 

 act of copulation is sufficient to impregnate a number 

 of eggs, while in others a repetition of the act is ap- 

 parently required to produce fecundation. 



Mr. Wright has collected a number of instances 

 showing that the eggs of the hen are fertile from four 

 to sixteen days after separation from the cock ; * and 

 it is a fact well known to breeders that, with turkeys, 

 a single copulation is sufficient to impregnate all the 

 eggs of one " laying," * while it is stated by Mr. Chapin, 

 of Milf ord, Massachusetts, " that a hen-turkey would 

 lay two or three successive litters of eggs, having been 

 impregnated only for the first litter." * 



1 Loc. tit., p. 130. 

 * Ibid., pp. 129, 130. 



3 Journal of the Royal Agricultural Society, vol. xii., p. 198 ; Teget- 

 meier's " Poultry-Book," p. 273 ; " The Illustrated Book of Poultry," 

 by Wright, pp. 130, 519. 



4 "Agricultural Report of Massachusetts," 1863, p. 57. 



