THE LIVING MACHINE BUILDING FACTORS. 153 



any forces in nature which are of such a sort as 

 to enable us to use them to explain the building 

 of machines ? Plants and animals are the only 

 machines which nature has produced. They are 

 the only instances in nature of a structure built 

 with its parts harmoniously adjusted to each 

 other to the performance of certain ends. All 

 other machines with which we are acquainted 

 were made by man, and in making them intelli- 

 gence came in to adapt the parts to each other. 

 But in the living organism is a similarly adapted 

 machine made by natural means rather than 

 artificial ? How was it built ? Does nature, 

 apart from human intelligence, possess forces 

 which can achieve such results 1 



Here again we must attack the problem from 

 what seems to be the wrong end. Apparently it 

 would be simpler to discover the method of the 

 manufacture of the simplest machine rather than 

 the more complex ones. But this has proved 

 contrary to the fact. Perhaps the chief reason 

 is that the simplest living machine is the cell 

 whose study must always involve the use of the 

 microscope, and for this reason is more difficult. 

 Perhaps it is because the problem is really a more 

 difficult one than to explain the building of the 

 more complex machines out of the simpler ones. 

 At all events, the last fifty years have told us 

 much of the method of the building of the com- 

 plex machines out of the simpler ones, while we 

 have as yet not even a hint as to the solution of 

 the building of the simplest machine from the 

 inanimate world. Our attention must, there- 

 fore, be first directed to the method by which 



