No. .w4] 



FITNESS OF ENVIRONMENT 



111 



the specific heat of water, as is actually the case, be nearly 

 or quite a maximum among all specific heats, it follows 

 that the fitness of water in this respect is nearly maximal. 



Again the ocean contains an astonishing variety of 

 substances in solution, and they are present often in large 

 quantities. In this manner a very great supply of food 

 in very great variety is offered marine organisms. Of 

 course such richness of the environment is an exceedingly 

 favorable circumstance for the organism, and it is due 

 principally to the ability of water to dissolve a multitude 

 of things in large quantities. It is not to be supposed that 

 the substances present in sea water are all of use to every 

 organism. This need not be the case at all, but a variety 

 of supplies which may be adapted to special requirements 

 as they arise, here iodine, there copper, for instance, is 

 a very genuine advantage. Further the vast utility of 

 the solvent action of water in blood, lymph, and all the 

 body fluids is too patent to call for comment. If, now, it 

 can be shown that the solvent power of water is nearly or 

 quite a maximum, as it really is, among all known sol- 

 vents, then it must be evident that in another respect the 

 fitness of water is nearly or quite maximal. 



Again the amount of energy that is required to tear 

 apart molecules of water and liberate hydrogen and oxy- 

 gen is very great indeed, and when hydrogen and oxygen 

 recombine to form water this energy must reappear,— 

 under ordinary circumstances as heat. This fact too is 

 very favorable for the organism, because almost all com- 

 pounds which contain hydrogen yield a great deal of 

 energy which can be tapped in the process of metabolism. 

 If therefore the heat of combustion of hydrogen be nearly 

 or quite a maximum, as it is, among all substances, it 

 is clear that water is again, in another respect, most 

 wonderfully fitted for life. Finally, if it be true, and 

 such is the case, that very few of the substances which 

 share the fitness of water "in one of these characteristics, 

 also share or approach its fitness in either of the others, 

 and that none possesses all these qualifications in a de- 

 gree that merits consideration, it must, I conceive, be ad- 



