122 OBSTETRICAL PHYSIOLOGY. 



also hypertrophied, the broad ligaments are increased in every direction, 

 but especially in length, and muscular fibres are abundantly developed 

 between their layers, in order to give them sufficient strength to sustain 

 the weight of the uterus. In the Cow, the fibres even form very distinct 

 intercrossing fasciculi. 



The greatest increase of all noted in the texture of the uterus, occurs 

 in the middle or muscular tunic. There appears to be a vast multiplica- 

 tion of the fusiform nucleated fibres going on during pregnancy, as well 

 as an immense increase in the volume of those already existing. This 

 tunic gradually becomes redder as well as thicker, and the muscular 

 fasciculi more distinct, and visibly more numerous. The inner layer, 

 composed of circular fibres, is most conspicuous in the cornua of carni- 

 vorus animals, and there they contract in the interspaces between the 

 young, so as to form well-marked constrictions. The connective tissue 

 which unites the muscular fibres also increases during pregnancy, and 

 becomes markedly fibrous. 



Sensibility. 



With the increase in volume, w-eight, and capacity, the uterus likewise 

 acquires a higher decree of sensibility^ doubtless from the development 

 of its nerves. So that between the cervix, the body, and the cornua, 

 there is established a sympathetic relation that is sometimes not advan- 

 tageous ; for irritation of the cervix, howsoever produced, may bring on 

 violent contractions of the whole organ, and lead to the premature ex- 

 pulsion of the foetus. This expulsion, as is well known, sometimes fol- 

 lows copulation ; though, as a rule, animals usually do no seek to copulate 

 during pregnancy if left to their own natural instincts. It may also be a 

 consequence of manipulation by the hand of the explorer. 



This contractility of the uterus is sometimes evidenced before parturi- 

 tion, when animals have been killed and quickly opened. Colin has wit- 

 nessed well-marked movements in the ut^Tus of a Cat which contained 

 five young — three in one horn and two in the other ; these contractions 

 were most energetic at the constricted spaces between the foetuses. The 

 same talented veterinary physiologist has seen similar phenomena in 

 Sheep at different periods of gestation ; the cornua contracted and dilated 

 alternately, approached or withdrew from each other or the body of the 

 uterus ; the movements persisting sometimes for forty or fifty minutes 

 after the animal's death. In a pregnant Cow opened when alive, the 

 same contractions were noted ; they became more active and stronger 

 under the influence of a slight irritation ; the cornua changed their form 

 in contracting ; they shortened sensibly, and became twisted on them- 

 selves at their anterior extremity. In a Mare identical contractions were 

 seen. 



Haller had long ago remarked that, even in the unimpregnated animal, 

 these uterine contractions were present — though they were most energetic 

 in the pregnant Bitches, Cats, and Rabbits he opened, the movement being 

 spontaneous and peristaltic, like that of the intestines, and that it con- 

 tinued in the organ, even when it was removed from the body. Those 

 veterinarians who have had occasion to insert their hand into the uterus of 

 one of the larger animals, to adjust the foetus or for any other object, 

 must have been astonished, and frequently embarrassed, at the firmness 

 with which the arm was grasped at the cervix during the expulsive efforts 

 the creature made. 



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