276 NOBMAL PAIITUIUTIOX. 



known as "after-pains" — the contractions being slow, gradual, and 

 continuous, and lasting until the whole of its inner surface is more or 

 less in contact, and its cavity has regained its ordinary dimensions. 

 In this process the muscular fibres continue to undergo alteration, the 

 contractions of the organ diminishing in force as this change goes on ; 

 and this change is essentially related to the conversion into fat of the 

 albuminous substance of the protoplasm of which their cells are com- 

 posed. The fibres become degenerated and absorbed, and it is some 

 time before they are replaced by others which have much smaller cells. 

 The bloodvessels of the organ also undergo similar alterations, after the 

 uterine contractions have more or less suspended the flow of blood in 

 their interior. They become wrinkled and sinuous and gradually less 

 permeable to the circulating fluid, the walls of the veins and capil- 

 laries are attacked by fatty degeneration, and are absorbed in large 

 numbers. 



This gradual interstitial absorption occurring after parturition, brings 

 about a considerable reduction in the weight and volume of the organ. 

 Thus the uterus of the Cow, which, immediately after delivery, will 

 weigh from thirteen to fifteen pounds, will be no more than seventeen 

 to twenty-one ounces when this process is completed ; and the uterus 

 of a Ewe w'ill be found reduced to a twelfth or thirteenth of its weight 

 at parturition. 



At the same time, the mucous membrane lining the organ is under- 

 going corresponding, but perhaps less profound, modifications to those 

 observed in woman after the uterus has got rid of its contents. "When 

 treating of the physiology of pregnancy, we described the manner in 

 ■which this membrane became enormously thickened, either wholly or 

 partially, to constitute a most important glandular and vascular 

 structure for the development of the young creature. But after 

 parturition, fatty degeneration attacks this structure and completely 

 destroys it in Solipeds and Euminants, and this destruction takes 

 place in a remarkably brief period in some animals. With the Bitch, 

 Cat, and Eabbit, as with woman, the whole of the glandular layer of 

 the membrane corresponding to the insertion of the foetal placenta — 

 the decidua vera — is completely detached and eliminated. 



In the former two, this exfoliation of the maternal placenta leaves 

 a depressed surface of equal extent, around which the thicker mucous 

 membrane forms a border like that seen in a cutaneous wound after 

 removal of the scab. On the surface of this exposed part, the 

 mucous membrane, being deprived of its epithelium, is very thin, 

 and so transparent that the muscular coat shines through it. 

 The uterus soon retracts and the placental wounds diminish in 

 size, becoming covered with granulations like other wounds. In a 

 Bitch which had only one puppy, five weeks afterwards the wound 

 was not quite healed, and its width was then about one centimetre ; 

 there were also observed other small annular surfaces, narrower than 

 the preceding, separated from each other by nearly equal intervals, 

 and having the mucous membrane very smooth, slightly thickened 

 and pigmented, and which, being found in all the pluriparous Bitches 

 and Cats examined, were believed to be old placentular cicatrices. 



In Euminants the cotyledons, which had gradually acquired such 

 large dimensions during pregnancy, shrink, their follicular receptacles 

 contract so as to be scarcely visible to the naked eye, and many of 

 these maternal placenta even appear to subside altogether, or to be 



