564 THE PLACENTA. 



structure, differs much in shape, size, position, and number in 

 different kinds of animals. The human female has one placenta 

 only; as is the case with the mouse, rabbit, guinea-pig, dog, 

 and cat :" so also with many animals which have the toes dis- 

 tinct, and incisor teeth in both jaws. " All those which have the 

 hoof cloven and incisors in one jaw onl} r , have several placentae, 

 whether they be domesticated animals, like the sheep, cow, and 

 goat, or wild, as the red-deer, roe, fallow-deer, and others of the 

 same kind. Again, where there is only one of these fleshy struc- 

 tures it either resembles a cake, (whence its name placenta), as in 

 the human female, rabbit, hare, mole, mouse, and guinea-pig ; or 

 else it is like a girdle or bandage encircling the trunk of the 

 body, as in the dog, cat, ferret, and the like." In some it 

 resembles the cup or chalice of the acorn, and surrounds the 

 greater part of the " conception," as in the hare and rabbit, 

 its convex part adhering to the uterus, the concave looking to- 

 wards the foetus. " Again, in animals which have this struc- 

 ture in the form of a cake, although the shape is similar, the 

 situation in which it is found is very different. In the human 

 female it adheres to the fundus of the uterus, and is as far re- 

 moved from the foetus as possible, their connexion being effected 

 by means of long vessels. In the mouse, guinea-pig, and rabbit, 

 it is attached partly in the region of the loins, partly at the 

 sides of the thorax. Those animals which have numerous pla- 

 centae are all furnished with incisors in one jaw only, as the 

 sheep, cow, goat, red-deer, roe, and the like. Yet in these 

 some variety is observable." 



For in the sheep the carunculse are many in number, and of 

 different magnitudes, the largest being of the size of a nutmeg, 

 the smallest of that of a pea or vetch : they are also of a 

 rounded form and reddish hue, with their convex portion turned 

 towards the uterus, something in the semblance of soft warts or 

 nipples. " In the cow they are larger, wider, and whiter, 

 more like a spongy or fungoid body," and they appear to take 

 their origin from the chorion. In the red or fallow-deer they 

 are five only in number; these spring from the walls of the 

 uterus, and thrust themselves inwards, exhibiting their depres- 

 sions or acetabula on the side of the foetus. But in all animals 

 it is observed that the carunculse adhere firmly to the uterus, 

 and cannot be separated from it without considerable difficulty, 



