582 THE WONDER OF LIFE 



under the given environmental conditions. The earth is 

 friendly to Uving creatures because in their physical 

 nature they are bone of her bone, and flesh of her flesh — 

 her very children. 



But it is an important piece of work to have shown that 

 organisms cannot be thought of as episodically or contin- 

 gently fitted to their environment, that the ' natural char- 

 acteristics of the environment promote and favour com- 

 plexity, regulation, and metabohsm, the three fundamental 

 characteristics of life '. The characteristics that make 

 them fit have contributed to the fitness of organisms. 

 It is no small service to have so clearly and circumstantially 

 suggested that Nature is Nature for a certain purpose. 



The Method of Evolution. — So far as we know as 

 yet, the method of organic evolution has been the method 

 of trial and error : ceaseless experimenting on the part of 

 the germ- cells, and the submission of these tentative new 

 departures to that criticism by the environment, which 

 we call Natural Selection. The experiments are called 

 ' variations ', and there is a growing body of evidence 

 to show that we must distinguish the minor fluctuations 

 from the major mutations. (It does not seem Ukely that 

 ' modifications ', or the direct results of pecuharities of 

 nurture in the wide sense, are of any direct importance 

 in evolution, since we have no secure evidence that they 

 are ever transmitted, as such or in any representative 

 degree. ) The facts in regard to ' mutations ', which we owe 

 to De Vries, Bateson, and others, point to the occurrence 

 of sudden and discontinuous variation ; ' the existence, 

 that is to say, of new forms having from their first beginning 

 more or less of the kind of perfection that we associate with 

 normality '. The general idea is that novel characters 



