14 DEFINITION OF PHYSIOLOGY. 



of the human uterus and placenta; the length of the umbilical 

 chord and the existence of the vesicula umbilicalis until the fourth 

 month ; together with the extreme delicacy of the cellular mem- 

 brane; are likewise structural peculiarities of the human race. 

 The situation of the heart lying not upon the sternum, as in quad- 

 rupeds, but upon the diaphragm, on account of our erect position, 

 the basis turned not, as in them, to the spine, but to the head, 

 and the apex to the left nipple ; the absence of the allantois, of 

 the panniculus carnosus, of the rete mirabile arteriosum, of the 

 suspensorius oculi ; and the smallness of the foramen incisivum, 

 which is not only very large in brutes, but generally double, 

 though not peculiarities, are striking circumstances. 



Man only can live in every climate l ; he is the slowest in 

 arriving at maturity, and, in proportion to his size, he lives the 

 longest of all mammalia ; he only procreates at every season, and, 

 while in celibacy, experiences nocturnal emissions. None but the 

 human female menstruates. 



Man, thus distinguished from all other terrestrial beings, evi- 

 dently constitutes a separate species. For " a species comprehends 

 all the individuals which descend from each other, as from a com- 

 mon parent, and those which resemble them as much as they do 

 each other" ;" and no brute bears such a resemblance to man. 



The knowledge of all the objects and laws of nature might be 

 supposed to be signified by the term physiology, derived as it is 

 from <fv<Ti^ nature, and Xo-yo?, a discourse. But the term is restricted 

 to vegetables and animals, and indeed solely to their functions. 

 The knowledge of their structure is designated ANATOMY ; the 

 knowledge of their functions PHYSIOLOGY. 



Both anatomy and physiology are divided into vegetable and 

 animal; and the latter again into brute, or comparative, and 

 human. The subject of the present work is HUMAN PHYSIOLOGY: 

 but the functions of brutes and vegetables will frequently be 

 mentioned. 



* Blumenbach accounts for this, and I think justly, by the two-fold operation, 

 of our intellect (I.e. 18. p. 54.), and of the more accommodating nature of 

 our frame (1. c. 17.). 



u Cuvier, Discows Preliminaire aux Recherches sur les Ossemens Fossiles des 

 Quadrupedes. 



