248 REVIEWS HUMAN PHYSIOLOGY. 



recognized as vital, and even styled empyreal air, was of course known 

 to be necessary to breathing animals, but whose action within and 

 without the system was not admitted to be the same in kind and 

 degree ; it is true that tardily and almost by compulsion the true 

 relation of this gas to respiration in its full meaning was perceived, 

 but whether its effects were confined to the lungs or extended to the 

 system at large, remained for at least forty years a mooted question even 

 up to the time of Edwards : to what was colorification attributed? 

 certainly to the action of oxygen, but not directly ; for, while arteri- 

 alization was the result of its absorption into the blood, and carbonic 

 acid was exhaled from the lungs, being formed therein, animal heat 

 was caused by the difference of capacity for caloric of arterial and 

 venous blood — an application of Black's theory of latent heat. La- 

 voisier had clear conceptions on the matter, which there is reason to 

 believe would, had he been permitted to give them, have anticipated 

 the exact views of the moderns ; yet with this exception and meagre, 

 timid and hesitating admissions of the possibility of such an action, 

 oxygen was held to oxygenate the blood and nothing more. Chemistry 

 was deemed too common and consequently too mean a science to hold 

 intercourse with life. For thus overlooking and depreciating the 

 agency of chemistry there is excuse ; it had hitherto done little for 

 physiology, and the latter rested but little and depended less on the 

 laws of the former for the elucidation of any of its functions : accurate 

 anatomists — pure solidists — the physiologists of that day, accounted 

 for the vital functions on mechanical principles. When, however, the 

 relation was perceived, it rapidly increased to closer connections and 

 inseparable alliance, so that in the cycle of the actual state of chemistry 

 we may limit our research to the air — to the soil — to the food derived 

 from both, and to the animal the aggregate microcosm of the three : 

 so may we trace down our biography and measure its intrinsic value. 



The work which heads this article is written by a professor of 

 chemistry, and is another proof of the advance in the manner already 

 pointed out. For several years we find that physiologists have more 

 and more trusted to chemistry for the explanation of many of the 

 obscure portions of their subject, and more and more have been multi- 

 plied works of physiological chemistry. Simon, and Lehmaxm, and 

 Robim and Verdeil, all attest this — and now reciprocally we see a 

 chemist become physiologist, which in truth every chemist virtually 

 must be. If man ever can attain to an absolute knowledge of his 

 functions, chemistry must undoubtedly be the light to guide him in 

 his path ; nor is this an unwarrantable assertion : at the enthusiasm 



