ADAPTATION TO ENVIRONMENT 19 



process of evolution as continuous from the birth of 

 the earth in star nebula? to the coming of man, al- 

 though it is unknown how many and how varied have 

 been the steps between, or how infinitely prolonged 

 has been the process. We know that vast periods of 

 time must have intervened between the inauguration 

 of motion and the appearance of forms approximating 

 our terrestrial rocks and gulfs; and that additional 

 myriads of ages must have been required to produce 

 the first ultramicroscopic particles of quasi-living 

 matter, which scientists regard as the probable step 

 intermediate between non-living and living matter. 

 How many more millenniums had to pass before un- 

 doubted moving, assimilating and reproducing forms 

 of life appeared, it is useless to conjecture. It is 

 probable, however, that the terrestrial stage was 

 already well stocked with reactionary factors in the 

 shape of gases, liquids, solids, light, changing tempera- 

 tures, and the like, when the first mass of ancestral 

 colloidal slime appeared. 



From colloidal slime to man is a long road, the con- 

 ception of which taxes our imaginations to the utmost, 

 but it is an ascent which is now fairly well demonstrated. 

 Indeed, the problems of the missing links are not so 

 difficult as is the problem of the origin of the organs 

 and functions which man has acquired as products of 

 adaptation. For whether we look upon the component 

 parts of our present bodies as useful or useless mecha- 

 nisms, we must regard them as the result of age-long 

 conflicts between environmental forces and organisms. 



As a result of the struggles for survival, there ensued 

 automatically an approximate adjustment of indi- 



