oU INTRODUCTION. 



As respects the position of the heart, some striking differences are 

 observable between Man and quadrupeds ; and the final cause of such 

 differences must certainly be ascribed to the destination of the former to 

 an erect, as of the latter to a horizontal mode of progression. The 

 form of the chest in Man, which may itself be taken as an index of his 

 erect attitude, permits the heart to assume an oblique direction to the left 

 side, and to rest on the diaphragm, to the tendinous expansion of which 

 muscle the pericardium is firmly attached ; but, in quadrupedal Mammalia, 

 the heart is seated in the centre of the chest, supported by the sternum, 

 while, between its investing membrane and the diaphragm, a considerable 

 space intervenes.* 



The arteries which supply the brain are so subdivided, in the gene- 

 rality of quadrupeds, as to prevent the blood from flowing with undue 

 rapidity into that organ : in Man, however, no such provision exists for 

 moderating its influx : in the horizontal mode of progression, therefore, 

 it would be poured into his brain with such copiousness as to expose 

 him constantly to the peril of apoplexy. 



As a sequel to this general review of the human skeleton, with refer- 

 ence to its fitness and adaptation for the erect attitude, the modifications 

 of parts presented by the osseous framework of the lower Mammalia, 

 according to the scale they occupy in the chain of being, and the modes 

 and purposes of their existence, have now to be considered. It may here 

 be observed, however, that a complete system of comparative osteological 

 anatomy is neither allowable by the nature or limits of this work : it will 

 be sufficient that such an outline of the subject is given as may be of 

 some value to the naturalist. It has been already said, that the skull 

 and the vertebral column are the essential parts of the skeleton. The 

 skull first demands attention. 



The bones of the skull may be divided into two sections ; those 



Many of the English farm-servants wear heavy stiff shoes ; and, in London, it surprises one to see the 

 drivers of country wagons with fine robust persons in the upper part, but with legs that are fleshless 

 spindles, producing a gait at once awkward and unmanly. One regrets that, for the sake of a tri- 

 fling saving, fair Nature should be thus deformed. The wives and sisters of those men, and their bro- 

 thers who are otherwise employed, are not thus mis- shapen. An example of an opposite kind is seen in 

 Paris, where, as there are no side- pavements in the streets, and the ladies consequently walk, almost 

 constantly, on tiptoe, the great action of the muscles of the calf has given a conformation of the leg 

 and foot, to match which the Parisian belles proudly challenge all the world. They are not aware, pro- 

 bably, that it is a defect in their city, to which the peculiarity of their form is in part owing." Elements 

 of Physics, pp. 212-13-14. 



With regard to these otherwise excellent remarks, it is proper to observe, that the tiptoe mode of 

 progression, although decidedly tending to a fine development of the calf, naturally produces, in the 

 same ratio, an undue increase of breadth in the forepart of the foot ; which, indeed, is conspicuously 

 displayed in the Parisian females, as compared with the more plantigrade women of the British metro- 

 polis. 



* Dr. Roget says, " Evidence is afforded of the human conformation being expressly adapted to the 

 erect position of the body, by the position of the heart, as compared with quadrupeds." Accord- 

 ing to Mr. Lawrence, " the Orangs (S. Satyrus, Troglodytes, and Gibbon) have it placed as in Man, 

 and the pericardium attached to the diaphragm ; in other Simiae," he adds, " the apex only is a little 

 inclined to the left, and touches the muscle." 



