88 THE NATURE OF LIFE 



IX 



THE CONTROL OF LIFE 



What shall we conclude from our sur- 

 vey of the tests of life? Certain of them 

 can be imitated to a remarkable degree 

 and seem to be reducible to mechanism. 

 In other cases we have not yet reached 

 this stage but we are making continual 

 progress toward a physicochemical ex- 

 planation, so that many investigators are 

 convinced that such an explanation must 

 eventually be reached. 



It is certainly true that all biologists 

 agree that the organism is in some re- 

 spects a machine but to what extent it 

 is a machine, is still a matter of contro- 

 versy. Some who think that the higher 

 organisms cannot be reduced to mechan- 

 ism feel no hesitation in regarding the 

 simplest forms of life as pure machines. 

 Such organisms are, however, suflSciently 

 complex to challenge our best powers of 

 analysis. While we can imitate more or 



