EVOLUTION— PYCRAFT 219 



one from another, to their "environment", but, as illustrated in the 

 case of Penicillium (p. 221), to their "chemotaxic" qualities, and the 

 nature of the "tissue" resulting from their metabolism, which made 

 different tissue out of the same food material. Each addition to the 

 structural comjDlexity in these different individuals, living in these 

 now mixed conimmiities, was an addition made in the processes of 

 repairing waste during the activities of the body, the areas most 

 stimulated by work taking up most of the products of digestion. 

 Thus began the evolution of the myriad forms of life which liave 

 come down through the ages till now. 



In other words, the necessary movements made in the search for 

 food, and the necessary reactions for the digestion and assimilation 

 of that food, brought about responses and reactions of the tissues 

 of the body of ever-increasing divergence as the different types 

 evolved — algae, bacteria, fungi — and so on to flowering plants and 

 trees; the Protozoa, Coelenterates, and so on, to man himself. 



Some of these, like the mole, the cetacea, the sloths, to take but 

 a few random examples, have become highly "specialized", and com- 

 mitted to a restricted amplitude of activities. And such are com- 

 monly supposed to have been molded by their "environment" and 

 not by their "proclivities." 



Doubtless environment is a factor in evolution, but the precise 

 part which it has played, and is playing, has yet to be defined. 

 Parasitic Protozoa, worms, and Crustacea like /Saccidina, and some 

 Cirripedes, may possibly be set down as cases of "environmental 

 adjustments." And the deep-sea fishes are in like case. 



Today there are many who still, unfortunately, regard such and 

 such an animal or plant as if it were merely a complex of tissues 

 forming the various parts or organs which make up its body, and 

 to regard these tissues, furthermore, as curiously and mysteriously 

 unstable, so that variations and permutations are always to be ex- 

 pected and always to be regarded, not so much as "fortuitous", as 

 in some intangible way brought about by changes in "environment", 

 giving rise to qualities, and changes, which endow that body with 

 an enhanced power of meeting the conditions of that environment, 

 animate or inanimate. So long as we accept this interpretation as 

 the mode of evolution, so long shall we fail to understand the 

 mysteries we are professedly trying to solve. 



Organisms, simple or complex, from amoeba to man, are not the 

 sport of chance variations after this fashion, dragooned, and "licked 

 into shape" by external conditions. They, in short, are not to be 

 regarded as so much clay molded into shape by the great potter, 

 "environment." Rather, we are to regard the various types of ani- 

 mals as self-regulating organisms, molded by the effects of the 

 persistent stimuli sustained by their several organs, or parts of 



