PREFACE. 



day ; it was the victory of philosophy over the 

 rudest empiricism. 



With all its discoveries, modern chemistry 

 has performed but slender services to physi- 

 ology and pathology ; and we cannot be de- 

 ceived as to the cause of this failure, if we 

 reflect that it was found impossible to trace 

 any sort of relation between the observations 

 made in inorganic chemistry, the knowledge 

 of the characters of the elementary bodies, and 

 of such of their compounds as could be formed 

 in the laboratory, on the one hand, and the 

 living body, with the characters of its constitu- 

 ents, on the other. 



Physiology took no share in the advancement 

 of chemistry, because for a long period she re- 

 ceived from the latter science no assistance in 

 her own development. This state of matters 

 has been entirely changed within five and 

 twenty years. But during this period physi- 

 ology has also acquired new ways and methods 

 of investigation within her own province ; and 

 it is only the exhaustion of these sources of 

 discovery, which has enabled us to look for- 

 ward to a change in the direction of the labors 

 of physiologists. The time for such a change 

 is now at hand ; and a perseverance in the 

 methods lately followed in physiology would 

 now, from the want, which must soon be felt, 



