338 QUARTERLY JOURNAL. 



observing, the shortest period of gestation was 240 days, and the 

 longest 321 : difference 81 days. 



Both of the foregoing statements differ from my experience. 

 Among my cows, though numbering only 62, the shortest period 

 of gestation was 213 days, and the longest period was 336 : dif- 

 ference 123 days. But as regards the shortest period of 213 days, 

 I must confess I have had my doubts as to the correctness, though I 

 kept the record myself, for in no other instance have they fallen 

 below 260 days. 



It would appear from the Earl's statements, that a calf produced 

 at an earlier period than 260 days, must be considered decidedly 

 premature ; and any calf produced at any period of gestation ex- 

 ceeding 300 days must also be considered irregular, but in this latter 

 case ihe health of the produced is not affected. 



There are some facts presented in my record, which differ from 

 any statements which have fallen under my observation. For in- 

 stance, in 1839 I had fourteen cows, three of which produced heifer 

 calves ; and the period of gestation averaged 284 days, while the 

 other seven produced males, and averaged 280 days. This, in regard 

 to the time allowed for males and females, is contrary to the prevalent 

 belief among farmers, and differs very materially from the result of 

 the following year, 1840. I had that year thirteen cows, six of 

 which produced heifer calves, whose period of gestation averaged 

 278 days ; and seven produced bull calves, averaging 299 days ; 

 the shortest period of the heifer calves was 213 days, and the 

 longest 336 days, being the greatest extremes of either year. The 

 shortest period of the bulls was 278 days, and the longest period 

 was 289 days. In this year the number of males and females were 

 nearly balanced. 



The next year, 1841, eleven cows produced eight heifer and 

 three bull calves. The shortest period of gestation for the heifer 

 calves was 277, and the longest 292 days, averaging 286 days. For 

 the bull calves the shortest period of gestation was 284, and the 

 longest 299 days, averaging 293 days. 



In 1842, the order seemed to be reversed ; for out of thirteen 

 cows, nine produced males, and four females. The shortest for the 

 males was 281, and the longest 294, averaging 287 days. There 

 was but very little difference in the time for the females ; the 

 shortest period being 280, and the longest 286, averaging 284 days. 



In 1843, the proportion of males to females, was, as in 1840, 

 nearly balanced. From eleven cows, six male and five female calves 

 were produced. The shortest period for the males was 277, and 

 the longest 290, averaging 282 days ; and the shortest period for 

 the females was 276, the longest 286, averaging 282 days. 



In the five years, which embraced my experiments, sixty-two 

 cows produced twenty-six females, and thirty-six male calves ; the 

 period of gestation for the bull calves averaged 288 days, while the 

 heifers averaged nearly 283 days. 



