152 



OBSTETRICAL PHYSIOLOa Y 



In the American Journal of the Medical Sciences for 1845, the result of 

 observations on 62 Cows gives the longest period as 336 days, and the 

 shortest as 213 days : the average for the male Calves being 288 days, 

 and females 282 days. 



An American breeder, in the Ne%c Live Stock Journal for July, 1882, 

 gives the following observations. Only Cows were noted which had a 

 single service, the Bull being kept isolated and no other Bulls accessible. 

 With an equal number of male and female Calves, the average with the 

 males was one day longer. 



Cattle-breeders, we believe, generally entertain the notion, notwith- 

 standing Earl Spencer's observations, that gestation is longer for a male 

 than a female Calf. 



It would appear that precocity has a notable influence on the dura- 

 tion of pregnancy in the Cow, in the more improved breeds the period 

 being shortened ; though the Calves at birth are not so well developed 

 as those of the common breeds. 



Sheep and Goat. 

 The Sheep and Goat go with young about five months. M. Magne 

 carefully noted the pregnancy of 429 Sheep at the Alfort Veterinary 

 School during a period of eight years, with the following result : 



2 instances of 143 days 



57 instances of 150 days 



From this list we observe that the difference between the longest 

 and shortest period was only thirteen days, by far the largest number 

 of births occurring between the 147th and 151st days ; the shortest was 

 143 days and the longest 156 days. The average duration of pregnancy 

 was about 149 days. Gestation was longer with the female than the 

 male Lambs, and this Magne attempts to explain by the greater develop- 

 ment and weight of the former, which rendered parturition more diffi- 

 cult and slow. 



Colin says the average period in the Sheep is 151 to 152 days, though 

 parturition may take place from the 145th to the 160th day. 



Dieterichs gives the shortest period as 146 days, the longest 157 — 

 average 151 days ; and Baumeister and Eueff state the shortest period 

 in the Sheep and Goat as 135 days, the longest 160 — average, 144 days ; 

 the male Lambs requiring, as usual, the longest period. With regard to 



