GREAT STEPS IN EVOLUTION 73 



CHARACTERISTIC FEATURES OF LIVING 

 I CREATURES. The chgmists tell us that the 

 * physical basis of life always includes pro- 

 teids and similar highly complex substances, 

 and that the process of living involves .an 

 j^tricate series of combustions and fermen- 

 tations andreconstructionSj many of which 

 can be imitated outside the body altogether 

 and expressed in chemical formulae. On the I 

 other hand we cannot give a chemical de-\ 

 scription of any complete vital function, or 

 of any activity of the living creature as a 

 whole and unless, as the Germans say, we 

 throw away the baby with the bath, we can- 

 not ignore the most salient fact, that all the 

 manifold chemical_processes are correlated 

 and controlled in a jmi'fied. behaviour, in a 

 Eurosive,_agency. Even the amoeba is no 

 fool. 



tell us that the living crea- 



ture resembles some wonderful kind of en- ] 

 gine; it_jg_a. material systenL^idapted to 

 * transform mattered energy; and it illus- 

 trates in its living a number of well-known f 

 physical phenomena, of surface-tension, of 

 diffusion, of elasticity, of hydrostatics, of ; 

 thermodynamics, of electricity, and so on. 

 At the same time it has to be admitted that 

 f not even the simplest vital activity, such as 

 (the passage of digested food from the ali- 



