THE LIVING MACHINE BUILDING FACTORS. 173 



surrounding the organism produce changes in it, 

 and that these variations, being handed down to 

 subsequent generations, constitute the basis of 

 the development of the machine. If this factor 

 is entirely excluded, we are driven back upon the 

 natural selection of congenital variations as the 

 only kind of variations which can permanently 

 effect the modification of the machine. 



Consciousness. It may be well here to refer to 

 one other factor in the problem, because it has 

 somewhat recently been brought into prominence. 

 This factor is consciousness on the part of the 

 animal. Among plants and the lower animals 

 this factor can have no significance, but conscious- 

 ness certainly occurs among the higher animals. 

 Just when or how it appeared are questions which 

 are not answered, and perhaps never will be. But 

 consciousness, after it had once made its appear- 

 ance, became a controlling factor in the devel- 

 opmentof the machine. It must not be understood 

 by this that animals have had any consciousness 

 of the development of their body, or that they 

 have made any conscious endeavours to modify its 

 development. This has not always been under- 

 stood. It has been frequently supposed that the 

 claim that consciousness has an influence upon the 

 development of an animal means that the animal 

 has made conscious efforts to develop in certain 

 directions. For example, it has been suggested 

 that the tiger, conscious of the advantage of being 

 striped, had a desire to possess stripes, and the 

 desire caused their appearance. This is absurd. 

 Consciousness has been a factor in the development 

 of the machine, but an indirect one. Conscious- 

 ness leads to effort, and effort has a direct influ- 

 ence in development. For example, an animal is 



