GESTATION. X41 



the tenth 324 days ; in the eleventh 330 ; in the twelfth 325". These 

 figures would go to prove that the period of gestation decreases with age ; 

 and indeed we find that the shortest pregnancies occurred in Mares 

 nineteen years old (316 and 318 days), and the longest in six and nine 

 years old Mares (354 and 348 days). 



The animals were of course kept in the most favorable conditions for 

 I:)reeding ; and this, with their splendid qualities and precocity, doubt- 

 less shortened the period of gestation, which is below the ordinary 

 average. 



It is commonly believed that the Cow is pregnant for the same length 

 of time as woman, and this is to a certain extent correct, so far as the 

 average period is concerned ; but there are variations which must be 

 taken into account, and which will be apparent if we look at the published 

 results of various observers. Of 1062 observations made at the Agricul- 

 tural School of Saulsaie, and by Blaine, Tessier, Grille, and Fiirstenberg, 

 we find that 15 were pregnant for less than 241 days, 52 from 241 to 270 

 days, 119 from 271 to 280 days, 544 from 271 to 300, 230 from 281 to 

 290 days, 70 from 290 to 300 days, and 32 beyond 301 days. So that it 

 would appear that, with the Cow, parturition is very rare before the 241st 

 day ; not so rare after the 300th day ; somewhat common from the 240th 

 to the 270th day; and quite common between the 280th and the 290th 

 day ; the average duration of pregnancy being about 283 days. Colin 

 gives an average of from 280 to 285 days, though birth may occur at the 

 250th to the 300th day, and even later. 



Dieterichs gives the shortest period as from 210 to 226 days ; the 

 longest between 326 and 353 days — average, 286 days ; while Baumeister 

 and Rueff give the shortest they observed as 240 days, and the longest 

 330 days — average, 285 days. The average of the Bernese Simmenthaler 

 breed at Hohenheim was 280^ days : male calves 283, and cow calves 

 278 days. 



Earl Spencer has furnished notes of 764 observations, which would go 

 to prove that no calf can be born alive before the 220th, nor after the 

 313th day, and that it is impossible to rear those born before the 24M 

 day. Those births which occurred before the 260th day he considered 

 as decidedly premature, while those which took place after 300 days were 

 classed as irregular. In 314 instances, 310 calved after the 285th day, 

 three went on to the 306th day, and one to the 313th. The average 

 given is 284 to 285 days. Among the calves born between the 290th 

 and 300th day, there was a decided preponderance of males ; all those 

 produced after the 300th day were females.. 



In the Amerian Joiirfial 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. 



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. 



^ Sheep and Goat. 



The Sheep and Goat go with young shout Jive months. M. Magna 

 carefully noted the pregnancy of 429 Sheep at the Alfort Veterinary 

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



