INTRODUCTORY REMARKS. 203 



from the imputation of exaggeration or the love of paradox in 

 establishing this proposition, that we again refer to those points 

 which we noticed under the head of Exudations (vol. in., p. 123), 

 and again in treating of the molecular forces which are active in 

 the animal body (pp. 163-168), where the lamentable condition 

 of our positive knowledge is too plainly showed. Qualitative 

 analysis fails us when we attempt to investigate the different 

 stages of transition and metamorphosis of the most essential 

 substrata of the tissues in a state of change, whilst the extractive 

 matters, in the absence of any rational explanation, have received 

 the most various interpretations, in accordance with the imaginative 

 ideas formed in reference to them by different observers. We have 

 more than once admitted our fear that there is no speedy prospect 

 of any great advance in qualitative chemical analysis, nowithstand- 

 ing the light which various departments of this branch of science 

 have derived from the genius of Liebig ; and we have, on the con- 

 trary, expressed our conviction that it required numerous and 

 more carefully conducted estimates of the quantitative relations of 

 the constituents of the different animal juices, before the mechani- 

 cal metamorphosis of matter could be placed on a sufficiently 

 secure foundation to admit of our studying its chemical nature. 

 We observed, in conclusion, that even the most exact measure- 

 ments of the masses and velocities of the molecular movements of 

 matter, in which vital activity is manifested, did not enable us to 

 attain to a truly scientific theory of the metamorphosis of matter 

 as long as we were constantly surprised by new and unexpected 

 observations on the action of molecular forces. Even if we had 

 mastered all the elements of this inductive inquiry, and could 

 trace the mechanical and chemical features of the metamorphosis 

 of matter, we should still be unable to comprehend the internal 

 connection of the individual links of this great chain of phenomena 

 we should be unable to master the causal dependence existing 

 between the different factors of vital motions in short, we should 

 be unable to give a scientific explanation of the mechanico-chemical 

 processes in the living organism, until we had acquainted ourselves 

 with the yet unknown laws of molecular forces. 



Before we attempt to take a general review of the molecular 

 movements in the animal organism, we think it will be expedient 

 to add to the above remarks upon the formation of organic 

 matter in the vegetable kingdom, a comparison between the action 

 of these forces in the two great divisions of living bodies the 

 vegetable and animal kingdoms. A comparison of this kind has 



