Il6 THE STORY OF THE LIVING MACHINE. 



then asked whether these fundamental properties 

 were themselves those of a chemical compound or 

 whether they were to be reduced to the action of 

 still smaller machines. The first answer which 

 biologists gave to this question was that assimila- 

 tion, growth, and reproduction were the simple 

 properties of a complex chemical compound. This 

 answer was certainly incorrect. Life activities 

 are exhibited by no chemical compound, but, so 

 far as we know, only by the machine called the 

 cell. Thus it is that we are again reduced to the 

 problem of understanding the action of a machine. 

 It may be well to pause here a moment to 

 notice that this position very greatly increases 

 the difficulties in the way of a solution of the 

 life problem. If the physical basis of life had 

 proved to be a chemical compound, the problem of 

 its origin would have been a chemical one. Chemi- 

 cal forces exist in nature, and these forces are 

 sufficient to explain the formation of any kind of 

 chemical compound. The problem of the origin 

 of the life substance would then have been simply 

 to account for certain conditions which resulted 

 in such chemical combination as would give rise 

 to this physical basis of life. But now that the 

 simplest substance manifesting the phenomena of 

 life is found to be a machine, we can no longer 

 find in chemical forces efficient causes for its for- 

 mation. Chemical forces and chemical affinity 

 can explain chemical compounds of any degree of 

 complexity, but they cannot explain the forma- 

 tion of machines. Machines are the result of 

 forces of an entirely different nature. Man can 

 manufacture machines by taking chemical com- 

 pounds and putting them together into such rela- 

 tions that their interaction will give certain results. 



