HEART^ VAGINA, &C. 17 1 



which it holds in quadrupeds. Its oblique direction to the 

 left side, its flat surface resting on the diaphragm, and the 

 firm attachment of its serous membrane to the tendinous 

 centre of that muscle, present, in the former, a contrast to 

 its straight situation in the middle of the chest, to its sup- 

 port on the sternum, and to the want of attachment between 

 the pericardium and muscle, which are even separated by a 

 distinct interval in the latter; a contrast easily explained by 

 the differences in the form of the thorax, and in the respec- 

 tive attitudes in the two cases. The orangs (S. satyrus, 

 troglodytes, and gibbon) have it placed as in man, and the 

 pericardium attached to the diaphragm. In other simise 

 the apex only is a little inclined to the left, and touches the 

 muscle. 



The curvature of the sacrum and os coccygis gives rise 

 to the peculiar situation and direction of the sexual organs, 

 and particularly of the vagina in the human female. As 

 these bones are extended in the same straight line with 

 the spine in all other mammalia, the canal of the vagina 

 follows the axis of the pelvis, lies nearly parallel to the 

 spine, and has its external orifice directed downwards or 

 backwards : the orifice of the urethra opens into the vagina 

 itself. These arrangements fully explain to us why brutes 

 discharge the urine behind, why they copulate backwards, 

 and why parturition is so easy with them. 



In these points of structure the monkey kind agree with 

 the mammalia in general, and differ from man. The axis 

 of the vagina is directed downwards in them ; the urine is 

 discharged within it (such at least, Blumenbach * found 



* De C. H, Var, Nat, sect. i. § T. The urethra does not, however, open 

 within the vagina of the orang-utang. Camper mentions that the nymphac 

 of this animal were ''comme r^unies ensemble," and that the urethra opened 

 below them. (Eiwrcs, i. 102. 



According to Cuvier, the female urethra always opens at the external 

 orifice of the vagina, and therefore holds the same situation, in respect to 

 this canal, in all animals. The canal exterior to this termination of the 

 urethra ho calls vulva. It is a simple entrance of little depth in the human 

 subject; ralhcr larger in the baboons; equal in length to the vagina itself in 



