20 The Universe and Life 



tions which we wish to examine. To judge of them, we 

 must look now at some features in the rising tide of 

 life. 



Development occurs both in the outwardly ob- 

 servable physical features of living things, and in 

 those inner characteristics which we discover through 

 the fact that we are ourselves biological specimens. In 

 the outwardly observable features, we find that the 

 structures and the physiological activities become, as 

 time passes, more and more complex and diversified. 

 At first the living material is relatively simple, 

 amoeba-like. Later it becomes complicated ; it trans- 

 forms into the higher plants and animals. And as it 

 transforms, both its structure and its activities be- 

 come in a high degree regulatory or adaptive. The 

 activities of the organism are carried on under the 

 stress and pressure of the surrounding physical con- 

 ditions. The organism indeed lives and acts through 

 and by means of the physical elements and condi- 

 tions ; it is itself an integrated group of such elements 

 and conditions ; it is, as it were, a whirlpool through 

 which they flow. Under the accidents and changes of 

 the physical conditions, the organism does not dis- 

 integrate ; it maintains its unity, its individuality. It 

 turns aside or opposes the currents of physical action 

 in such a way as to maintain its structures and its 

 essential internal processes. It exercises a selective 

 action, admitting those elements and conditions that 

 are favorable to its life processes, rejecting or fleeing 

 from those that are unfavorable. In doing this the 

 organism produces, as time passes, complex machine- 



