MOLECULAR FORCES. 177 



renewed motion ; as, for instance, a single atom of oxalic acid is 

 able to convert a hundred and more atoms of oxamide into oxalate 

 of ammonia, or as a single vesicle of air can produce fermentation 

 in infinite quantities of vegetable juice, or as the avalanche which 

 increases in mass as well as in velocity as it rushes down the snow- 

 covered declivity of the mountain side. This kind of vital motion 

 is at least not at variance with physical laws, whilst it presents 

 analogies with purely mechanical motions. It is these analogies 

 which the investigator of nature must endeavour to detect in vital 

 motion, in order to deduce from the known factors the still unknown 

 coefficients of this motion. The vital law cannot be discovered 

 and elucidated until the chemical and physical laws by which these 

 motions are regulated have been thoroughly investigated and dis- 

 tinctly recognised. 



It appears strange, and scarcely reconcilable with physical 

 laws, that the molecular motions in the living organism should so 

 rarely deviate from their prescribed course, notwithstanding the 

 innumerable causes which are constantly threatening to disturb 

 them. Organic vital motion is neither straight nor uniform: all 

 its manifestations exhibit an oscillating character, appearing inva- 

 riably to incline first in one and then in another direction, although 

 some compensating property seems to prevent excess beyond a 

 certain limit. As the influence of heat is compensated in the 

 animal body by the increased evaporation of the fluids, like the 

 action of the same agent on the compensation-pendulum ; so also 

 in organic motion, notwithstanding its extreme fluctuations, regu- 

 larity is maintained by some one predominant force being spon- 

 taneously arrested, and by the simultaneous action of different 

 particles in motion, which neutralise on the one side what might 

 from the other side give rise to a disturbance in the regularity of 

 the organic motion. The existence of this compensating capacity in 

 organic motion meets with the fullest confirmation in its abnormal 

 or pathological phenomena, which have consequently been regarded 

 as affording the most convincing proofs of the reality of a wise and 

 provident vital principle. 



Although the dogma of the vital force cannot be wholly passed 

 by in a text-book of physiological chemistry, we should not have 

 treated it with the completeness with which we formerly* con- 

 sidered it, if there were not some cause of apprehension that there 

 might occur a reaction in reference to this question, and that vital 

 force, even if it did not regain its former position, might yet obtain 

 * In the first part of the original edition. 



VOL. III. N 



