The Fitness of the Environment: An Inquiry into the Biological Significance of the Properties of Matter.

Darwinian fitness is compounded of a mutual relationship between the organism and the environment.Of this, fitness of en- vironment is quite as essential a component as the fitness which arises in the process o* or- ganic evolution ; and in fundamental charac- teristics the actual environment is the fittest possible abode of life.Such is the thesis which the present volume seeks to establish, This is not a novel hypothesis.In rudimen- tary form it has already a long history behim it, and it was a familiar doctrine in the early nineteenth century.It presents itself anew as a result of the recent growth of the science of physical chemistry.About fifteen years ago I first became inter- ested in the connection between physical and chemical properties of simple substances and the organic functions which they serve.At that time the applications of the new physical chemistry to physiology were only just begin- ning, and the older speculations of natural theology upon such subjects had long since v PREFACE vii lation of neutrality (the concentration of ion- ized hydrogen and hydroxyl at the neutral point).One does not like to accept a fact of such far-reaching importance as mere chance, and yet no other explanation was at hand.For, after the briefest consideration, it was obvious that here, at least, natural selection could not be involved.But it was also certain that tin's is no unique instance of a property of a simple substance automatically serving a very useful purpose in the processes of life.Like every one who has received a chemical training, Iwas vaguely conscious of numerous other simi- lar cases ; like every one who has any acquaint- ance with the general properties of matter, I knew that the remarkable thermal properties of water are of great importance to living or- ganisms.However, in spite of the fact inat I had been brought face to face with a definite problem whose solution now appears to he perfectly patent, so great is the natural inertia of the mind, and so firmly established was thf belief that natural selection is, on the whole, quite adequate to account for biological fit- ness, that for a number of years I made no further progress.Then, finally, after a long period of uncer- tainty, came the realization of the reciprocal viii PREFACE character of Darwinian fitness, and at once the whole difficulty was resolved.On all sides instances of environmental fitness were manifest, and casual search brought many other cases to light.The forgotten literature of natural theology is crammed with illustra- tions, and the recent biological developments of physical chemistry have provided still others.It is, indeed, a very curious episode in the history of thought that these well- known facts should have been so long forgot- ten or misconstrued.But, though forgotten, they have, so to speak, lain dormant in the minds of physical scientists, and I have found both chemists and physicists ready to accept them without hesitation.In the following pages an attempt has been made to collect and to interpret such facts, in so far as they arise among the compounds of carbon, hydro- gen, and oxygen, especially in the cases of witer and carbonic acid.This restriction has been adopted in order to facilitate the logical discussion, and it should be borne in mind that other phenomena, dependent upon the properties of other substances, such as the above-mentioned characteristics of phosphate solutions, belong in the same category.The argument which has been thus devel- oped is comparatively rigid and closely woven.