LIVING THINGS AND MACHINES 113 



Oscar Hertwig l and as there is no living biologist Hertwig 

 whose reputation stands higher than his it will be 

 useful to quote him in extenso, rather than to give 

 a catena of quotations from other persons. He 

 commences by saying that it is the more necessary 

 that this matter should be set in the proper light 

 because there is a growing tendency at the present 

 time to try and explain the living organism in the 

 terms of a machine and to believe that organic 

 operations can be accounted for in this matter. 

 He himself maintains that very important differ- 

 ences exist between a living organism and a 

 machine. 



A machine can only operate in one or at most 

 in a few directions and that in an unchangeable 

 manner in accordance with its original construction. 

 Its individual parts cannot, by their own power, 

 rearrange themselves, or enter into new combina- 

 tions in correspondence with the new conditions 

 with which they may find themselves confronted. 

 Therefore the machine cannot react to outer influ- 

 ences in a purposeful and many-sided manner. 

 The organism, on the contrary, has an innate 

 power of construction. The single cell, the first 

 step in the direction of an organism, is irritable 

 towards warmth and light as well as towards all 

 kinds of mechanical and chemical influences and 

 1 Op. cit., s. 141. 



