THE LIVING MACHINE BUILDING FACTORS. 187 



struction of artificial machines has demanded in- 

 telligence. But here is a natural machine the 

 organism. It is the only machine produced by 

 natural methods, so far as we know ; and we have 

 therefore next asked whether there are, in nature, 

 simple forces competent to build machines such 

 as living animals and plants ? 



In pursuance of this question we have found 

 that the complicated machines have been built 

 out of the simpler ones by the action of known 

 forces and laws. The factors in this machine 

 building are simply those of the fundamental vital 

 properties of the simplest protoplasmic machine. 

 Reproduction, heredity, and variation, acting 

 under the ever-changing conditions of the earth's 

 surface, are apparently all that are needed to ex- . 

 plain the building of the complex machines out of 

 the simpler ones. Nature has forces adequate to 

 the building of machines as well as forces ade- 

 quate to the formation of chemical compounds 

 and worlds. 



But here again we are unable to base our ex- 

 planation upon chemical and physical forces. 

 Reproduction, heredity, and variation are prop- 

 erties of the cell machine, and we are therefore 

 thrown back upon the necessity of explaining the 

 origin of this machine. Can we find a mechanical 

 or chemical explanation of the origin of proto- 

 plasm ? A chemical explanation of the cell is im- 

 possible, since it is not a chemical compound, but 

 a piece of mechanism. The explanation given 

 for the origin of animals and plants is also here 

 apparently impossible. The factors upon which 

 that explanation depended are factors of this 

 completed machine itself, and'can not be used to 

 explain its origin. We are left at present there- 



