MUliIFICATKiXS IX THE rTKIU'S. l:Jl 



wt'll as- an immense increase in the volume of those already existing'. 

 This tunic gi'adually becomes redder as well as thicker, and the muscular 

 fasciculi more distinct, and visibly more numerous ; its contractile 

 power also increases. The inner layer, composed of circular fibres, is 

 most conspicuous in the cornua of Carnivorous animals, and there tlii'y 

 contract in tlie interspaces between the younj^, 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, weight, and capacity, the uterus like- 

 wise acquires a higher degree of sensibility, doubtless from the develop- 

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

 cornua, there is established a sympathetic relation that is sometimes 

 not advantageous ; for irritation of the cervix, howsoever produced, 

 may bring on violent contractions of the whole organ, and lead to the 

 premature expulsion of the foetus. This expulsion, as is well known, 

 sometimes follows copulation ; though, as a rule, animals usually do 

 not 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 par- 

 turition, when animals have been killed and quickly opened. Colin 

 has witnessed well-marked movements in the uterus 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 

 fa-tuses. The same talented veterinary physiologist has seen similar 

 phenomena in Sheep at different periods of gestation ; the cornua con- 

 tracted and dilated alternately, and 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 themselves at their anterior extremity. In a 

 Mare identical contractions were seen. 



llaller had long ago remarked that, even in unimpregnated animals, 

 these uterine contractions were present—though they were most ener- 

 getic in the pregnant Bitches, Cats, and Rabbits he opened ; the move- 

 ment was spontaneous and peristaltic, like that of the intestines, and 

 it continued 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 fcctus or for any 

 other object, must have been astonished, and frequently embarrassed, 

 at the firmness with which the arm was grasped at the cer\-ix during 

 the expulsive efforts the creature made. 



These uterine contractions are very powerful, and in all probability 

 their rliythm is analogous to that of the intestines — extending from the 

 extremity of the cornua towards the cenix in a peristaltic manner, 

 particularly in tiiose animals which, like the Bitch and Pig. have very 

 long cornua, with the young arranged one after another in them. 



This increase in sensibility which the uterus acquires during gesta- 

 tion, must be considered as the organic cause of its contractions ; the 

 sensibility and contractility gradually diminish after parturition, during 



