METHODOLOGICAL INTRODUCTION. 3 



phenomena and of well-established facts, which easily admit of 

 being reduced to definite laws, in the former we must necessarily have 

 recourse to experiments and natural investigations, whose success 

 must in a great measure depend on individual operations of the 

 mind. Zoo-chemical processes are the most complicated of any 

 comprised in the domain of natural enquiry ; but such processes 

 are not capable of tangible demonstration, but must be divined, or 

 rather, intellectually apprehended. Our senses are incapable of per- 

 ceiving the causal connexion of things, or the logical succession of 

 phenomena ; thus we do not see motion, but simply recognize it by 

 the result of the changes effected by it ; we do not perceive heat, but 

 simply the variations of the temperature, and the results to which 

 they give rise, &c. Hence it is not our senses which here deceive 

 us, but the judgment which we form regarding the objects pre- 

 sented to us by the perceptive faculties. The causal connexion of 

 several allied phenomena, (i. e., a process,) can therefore only be 

 comprehended by the subjective combination of individual objects 

 perceived by the senses, and not by sensuous intuition alone. 

 But as soon as we subject to investigation the highly compli- 

 cated chemical phenomena of life, we enter upon the actual domain 

 of hypothesis. It unfortunately happens, however, that the correct 

 logical conception of an hypothesis has been completely lost sight of, 

 and its place supplied by the vaguest fictions ; whence the term has 

 fallen into such discredit that many have been desirous of setting 

 aside all hypotheses, unmindful that even the simplest form of expe- 

 riment cannot be prosecuted without their aid. Hypotheses are 

 indispensable in every physical enquiry, and must constitute the base 

 of every experiment, as they are in fact merely the subjection of 

 our thoughts and mode of intuition to the reality of phenomena. 

 The question, however, always is, whether the facts at our command 

 logically justify such a procedure, since where such is not the case, the 

 deduction at which we arrive is undeserving the name of an hypothesis, 

 and is a mere fiction, supported at best on a hypothetical foundation. 

 Physiological chemistry has given rise to many delusions of 

 this nature, owing to its imperfect development, and to the 

 necessity presented by physiology and pathology for chemical 

 elucidation. Some few isolated deductions were drawn from 

 superficial chemical experiments, and arranged in a purely 

 imaginary connexion by the aid of chemical symbols and formulae, 

 for whose establishment analysis in many cases did not even afford 

 any sanction. Thus, for instance, in the attempt to form a con- 

 clusion regarding the metamorphosis of the blood from an elemen- 



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