74 THE BREEDING OF ANIMALS 



was 288 days and for females 283 days, but in 1839 the 

 female calves were carried longer than the males. Earl 

 Spencer 1 also believed there was some relation between 

 sex and the length of gestation. M. Magne 2 found the 

 period of gestation longer "for ewe lambs than for ram 

 lambs. C. U. Connellee 3 of Texas finds no relation be- 

 tween the sex of foals and the time required for gestation. 

 The evidence available is insufficient to justify the belief 

 that male offspring are carried longer than females. 



68. Incubation. The period of incubation in fowls 

 represents in oviparous animals the phenomenon of gesta- 

 tion in mammals. The length of the period of incubation 

 among domestic birds is given by Miles 4 as follows : 



" Turkey, twenty-six to thirty days ; guinea hen, 

 twenty-five to twenty-six days; pea-hen, twenty-eight 

 to thirty days; ducks, twenty-five to thirty-two days; 

 geese, twenty-seven to thirty-three days ; hens, nineteen 

 to twenty-four days, or an average of twenty-one ; pigeons, 

 sixteen to twenty days; canary-birds, thirteen to four- 

 teen days. Mr. Wright remarks that ' cold weather, or 

 a prevailing east wind, will lengthen the time a day or 

 more, while warm weather and an attentive sitter will 

 hasten it ; stale eggs also hatch later than fresh/ ' 



The smaller breeds, like bantams, hatch in nineteen 

 or twenty days, while the heavier breeds may require 

 as long as twenty-two days for complete incubation. 

 When eggs are artificially incubated, it has been found 

 that a higher temperature combined with favorable 

 moisture conditions will shorten the period. 



1 Spencer, Journal of the Royal Agricultural Society, vol. 1, 

 p. 168. 2 Loc. cit. 



3 Breeder's Gazette, June 26, 1907. 



4 Miles, "Stock Breeding," p. 401. 



