THE ENVIRONMENT 71 



heat of vaporization, has been utilized through 

 adaptation of the organism to secure very 

 high efficiency in a physiological process. 



Such is the method which must be followed 

 in order to decide the question of the fitness of 

 the environment. The physico-chemical char- 

 acteristics of water, carbonic acid, and the 

 carbon compounds are to be taken up one by 

 one, and their absolute and relative magnitudes 

 considered. The possible utility of such proper- 

 ties, both automatically and through process of 

 organic adaptation, must then be estimated, 

 bearing in mind the fundamental characteris- 

 tics of the living organism which have been 

 arbitrarily postulated. Finally the various 

 favorable qualities of water, carbonic acid, 

 and the carbon compounds must be grouped 

 together in order to see if they constitute a 

 unique ensemble of fitness, among all possible 

 chemical substances, for a living organism 

 which must be complex, regulated, and en- 

 gaged in active metabolism. 



At length the problem of fitness appears in 

 a simple form. The road to a solution is 

 open, and we may now proceed to an untram- 

 meled discussion of unexceptionable data and 

 well-known laws of physics, chemistry, meteor- 

 ology, and physiology. Without further hypo- 

 thetical difficulties, these must lead to the goal. 



