408 PRINCIPLES OF STOCK-BREEDING. 



observed in merino and Southdown sheep that has 

 been noticed. 



In swine, " according to Nathusius, the period is 

 shortest in the races which come early to maturity ; 

 but in these latter the course of development does not 

 appear to be actually shortened, for the young animal 

 is born, judging from the state of the skull, less fully 

 developed or in a more embryonic condition than in 

 the case of common swine, which arrive at maturity 

 at a later age. 1 



It seems to be the general opinion that the period 

 of gestation is longer with male than with female off- 

 spring ; a but there appears to be no sufficient evidence 

 on record to warrant such a conclusion. 



In the observations of Mr. Bement, from " those 

 cows that exceeded 286 days, the number of females 

 was seven, while that of the males was twelve. The 

 number of female calves produced under 283 days 

 was twenty-four, while that of the males was thirty- 

 one." ! There was thus a larger proportion of males 

 in the periods above and below what may be consid- 

 ered an average, and it is worthy of remark that the 

 produce in the longest-observed period was a heifer. 



The average period was the same for males and 

 females in 1845, was longer for females in 1839, and 

 longer for males in the three remaining years. The 

 average for the five years was 288 days for males and 

 283 days for females. 



1 Darwin, "Animals and Plants under Domestication," vol. i., p. 96. 

 1 " British Husbandry," vol. ii., p. 438 ; Randall's " Practical Shep- 

 herd," p. 207. 



3 The Cultivator, 1845, p. 207. 



