260 Anatomy and Physiology of the 



cows in calf to certain bulls exceeding- the usual period, and a 

 small proportion falling short of it. Hence we must attribute 

 the prolongation of the period to some peculiarity in the embryo, 

 derived from its male parent." * Alluding to the opinion which 

 is also entertained with respect to the sex of the foetus influencing 

 the time of gestation, Earl Spencer observes, tf there is a preva- 

 lent belief among farming men, and I believe farmers, that, when 

 the time of gestation of a cow is longer than usual, the produce 

 is generally a male calf. I must confess that I did not believe 

 this to be the case, but this table shows that there is some 

 foundation for the opinion. In order fairly to try this, the cows 

 who calved before the 260th day, and those who calved after the 

 300th, ought to be omitted as being anomalous cases, as well as 

 the cases in which twins were produced ; and it will then appear 

 that, from the cows whose period of gestation did not exceed 

 286 days, the number of cow-calves produced was 233, and the 

 number of bull-calves 234 ; while from those whose period 

 exceeded 286 days, the number of cow-calves was only 90, while 

 the number of bull-calves was 152." This places the matter in 

 so clear a light that it is unnecessary to add another word, and 

 therefore I shall pass on to the last division of this lecture, 

 namely, natural and preternatural parturition. 



Labour, although perfectly natural, may occupy some time, or 

 be rapidly effected ; we observe a considerable difference in this 

 respect among the different animals which man by domestication 

 has rendered subservient to his use. Delivery under ordinary 

 circumstances is quick in the mare, the birth of the foal rarely 

 occupying more than a few minutes ; in the cow half an hour 

 may be regarded as about the average time after labour-pains 

 show themselves ; while in the ewe it not unfrequently happens 

 that several hours will be spent in labour. I will here advert to 

 a table in which I have attempted a classification of labours, 

 showing the several varieties met with in practice. 



CLASSIFICATION OF PARTURITION. 



Division. Variety. 



Natural Quick. Lingering. Twin. 



Preternatural . . . Lusus Naturse. Every kind of Malpresentation. 

 Premature .... do. do. 



Protracted .... Mechanical Impediments. Imperfect Throes. 

 Impractical .... Maternal Defects. 

 Instrumental . . . Destructive, or not, of the Foetus. 



Uterine Dropsy, Hemorrhage, Rupture. 

 Inverted Vagina, Bladder, Rectum. 

 Complicated . . . { Ruptured do. do. do. 



Scirrhous Os Uteri, Lacerated Vulva. 

 &c. &c. &c. 



Carpenter's " Manual of Physiology," p. 478. 



