10 METHODOLOGICAL INTRODUCTION. 



lectures and writings of many physicians, that, trusting to the 

 aphoristic and often highly apodictic assertions of certain chemists, 

 they felt secure of having reached the object of their enquiries. 

 Although at present little more than the direction is indicated, we 

 may hope in due time, and after innumerable efforts, to see our 

 endeavours crowned with success. 



After having become acquainted with the deficiencies and errors 

 belonging to the chemistry of the vital processes, which was so pro- 

 minently brought forward at an earlier era, we will now pass to the 

 methods and principles by which alone this science can be made to 

 fulfil its just requirements. The final result of all physiologico- 

 chemical investigations is avowedly that of gaining an accurate 

 knowledge of the progress and causal connexion of the chemical phe- 

 nomena attending the vital processes. To attain to this knowledge, 

 it is not sufficient to detach separate parts from the mechanism of 

 the whole, and to form an opinion of the combined action of so com- 

 plicated a chemical structure from a more or less superficial exam- 

 ination. Attempts have already been made to establish a splen- 

 did theory of the metamorphosis of tissues, but notwithstanding 

 the many able heads and hands that have been engaged in the 

 labour, it is still deficient in the essential of a solid foundation. 



It is unnecessary to prove that we must thoroughly understand 

 the substrata of the metamorphosis of the animal tissues before we 

 can venture an opinion on the nature of the processes. The surest 

 supports of physiological chemistry are to be sought, therefore, in 

 general organic chemistry ; while the study of the organic sub- 

 strata of the animal body, or zoo-chemistry considered in the 

 strict sense of the word, must necessarily constitute an integral 

 part of physiological chemistry and prove a most efficient aid 

 towards its development. If zoo-chemistry ever fulfil its object, it 

 must be by the joint aid of chemistry and physiology ; that is to 

 say, individual substances must not only be fully examined in refe- 

 rence to their chemical value and their place in the domain of pure 

 organic chemistry, but they must also be observed in the more 

 general relations which each may bear to the animal organism and 

 its metamorphosis. In a word, the physiological value of each 

 substance should be as carefully considered in zoo-chemistry 

 (the basis of physiological chemistry) as in pure chemistry. It 

 seems to us, that in treating of zoo-chemistry (in the first volume of 

 this work,) we shall the best attain this aim by adopting the follow- 

 ing arrangement : namely, by treating of the chemical relations of 

 each body in reference to its properties, composition, combinations, 



