THE LIVING ORGANISM 31 



important in the field of cosmic evolution. We must 

 begin with the living organism ; and how the first one 

 arose must be of less importance to us than the knowl- 

 edge of its mechanical constitution and of its mechani- 

 cal operation. Of far greater value is the realization 

 that a living creature is not an independent thing, but 

 that, on the contrary, it must hold the closest possible 

 relations with the world of materials and energies con- 

 stituting its environment. We must again insist upon 

 the importance of that mechanical adjustment to the 

 conditions of life which is the universal characteristic 

 of plants and animals. It is the history of these crea- 

 tures and the origin of their adapted conditions that 

 we are called upon to study. We must scrutinize the 

 nature of to-day to see if we can find evidence that 

 evolution is true, and if we can discern the forces which, 

 acting upon the living mechanism as man has dealt 

 with machines, might bring the various species of the 

 present day to their modern forms. 



We have now learned that evolution means a common 

 ancestry of living forms that have come to differ in the 

 course of time ; our common reason has shown us also 

 that organisms are in a true sense complicated chemical 

 mechanisms adapted to meet the conditions under which 

 they must operate. We come now to the evidences 

 offered by the organic world that evolution is true and 

 that natural forces control its workings. Clearly the 

 examination of the matter of fact is independent of the 

 question of method. For just as the chemist may ex- 

 periment with various substances to see if they will 



