AIM AND PROGRESS OF PHYSICAL SCIENCE. 337 



Meanwhile it is true that exact quantitative determinations of 

 the equivalents of force, consumed and produced in the vegetable 

 as well as the animal kingdom, have still to be made in order 

 to fully establish the exact accordance of these two values. 



If, then, the law of the conservation of force hold good also 

 for the living body, it follows that the physical and chemical 

 forces of the material employed in building up the body are 

 in continuous action without intermission and without choice, 

 and that their exact conformity to law never suffers a moment's 

 interruption. 



Physiologists, then, must expect to meet with an uncon- 

 ditional conformity to law of the forces of nature in their in- 

 quiries respecting the vital processes ; they will have to apply 

 themselves to the investigation of the physical and chemical 

 processes going on within the organism. It is a task of vast 

 complexity and extent ; but the workers, in Germany especially, 

 are both numerous and enthusiastic, and we may already affirm 

 that their labours have not been unrewarded, inasmuch as our 

 knowledge of the vital phenomena has made greater progress 

 during the last forty years than in the two preceding cen- 

 turies. 



Assistance, that cannot be too highly valued, towards the 

 elucidation of the fundamental principles of the doctrine of 

 life, has been rendered on the part of descriptive natural history, 

 through Darwin's theory of the evolution of organic forms, by 

 which the possibility of an entirely new interpretation of organic 

 adaptability is furnished. 



The adaptability in the construction of the functions of the 

 living body, most wonderful at any time, and with the progress 

 of science becoming still more so, was doubtless the chief reason 

 that provoked a comparison of the vital processes with the 

 actions of a principle acting like a soul. In the whole external 

 world we know of but one series of phenomena possessing simi- 

 lar characteristics, we mean the actions and deeds of an intelli- 

 gent human being, and we must allow that in innumerable in- 

 stances the organic adaptability appears to be so extraordinarily 

 superior to the capacities of the human intelligence that we 



