GESTATION. 



123 



These uterine contractions are very powerful, and in all probability 

 their rhythm is analogous to that of the intestines j extending from the 

 extremity of the cornua towards the cervix in a peristalic manner, par- 

 ticularly in those animals which, like the Bitch and Pig, have very long 

 cornua, and the young arranged one after another in them. 



This increase in sensibility, which the uterus acquires during gestation, 

 must be considered as the organic cause of its contractions ; the sensi- 

 bility and contractility gradually diminishing after parturition, during 

 which it reaches its apogee. Its contractility, which signifies also its 

 retractility, enables it to .contract on itself after delivery, and to nearly 

 obliterate its cavity. This rapid diminution in the capacity of the organ 

 closes the orifice of the vessels which open on its internal surface during 

 the act, and thus prevents fatal haemorrhage. 



Its main function, however, appears to be concerned in the expulsion 

 of the foetus, and then, as at other times, it is entirely independent of the 

 will. Besides, its intensity is not always related to the strength of the 

 animal ; pain deadens and paralyzes the contractile force, as is seen in 

 primiparous creatures. When the contractions have been vigorous, the 

 uterus rapidly diminishes ; but if they have been slow and weak, the 

 organ slowly contracts on itself. When -it does not contract quickly after 

 delivery it is said to be inert, and the cause is to be found in the expend- 

 iture of its contractile power, either through excessive distention, a 

 delivery too prompt or too slow, or general w^eakness of the maternal 

 system.. By long exercise, like voluntary muscles, those of the uterus 

 become weakened ; so that when the act of parturition has been pro- 

 tracted, the contractions of the organ become slow and feeble, or cease 

 altogether. Opiates and narcotics generally produce the same effect, 

 and are therefore successfully administered when the contractions are 

 too energetic or painful during delivery, or before abortion. The con- 

 tractions are stimulated by irritation of the cervix or body of the uterus : 

 such as ,is produced by retention of the whole or a portion of the placenta, 

 titillation of the cervix by the finger, frictions on the belly, the applica- 

 tion of cold to this part, or the administration of ergot of rye. 



Form. 



The uterus, after conception, begins to change inform as well as in 

 volume and structure ; this alteration, like the others, proceeding pari 

 passu with the develepment of the fcetus. The body becomes round, 

 and in the carnivora, as already described, the cornua elongate and show 

 the alternate dilatations and constrictions due to the presence of the 

 young in their cavities. In the Mare, Cow, and Sheep, if there is but 

 one foetus, a single horn is enlarged — usually the right — to contain the 

 posterior limbs, and the other is relatively smaller and contracted, and 

 looks a mere appendage. When a carnivorous animal contains only one 

 foetus, it is developed in the horn, and not in the body of the uterus, and 

 it is not until parturition commences that it descends into the latter ; 

 should the creature die before delivery, the offspring will be found there. 

 In this species each horn generally contains one or more young ; should 

 there be only two, one occupies each cavity ; but when there is only one 

 foetus, it is then in one of the cornua. 



The changes taking place in the cervix of the uterus during pregnancy 

 have not been accurately ascertained in the domesticated animals ; as in 

 the smaller species there is usually no occasion or necessity to make an 



