Mechanism, Vitalism, and Teleology 355 



ties of life are : ( I ) protoplasmic and cellular organization, 

 (2) metabolism, (3) reproduction, (4) sensitivity, (5) 

 adaptability. 



Are these properties explicable in terms of physics and 

 chemistry, and to what extent may they be duplicated in 

 not-living matter? Does the law of cause and effect apply 

 here as elsewhere in nature? Theoretical mechanism would 

 answer each of these questions in the affirmitive, vitalism in 

 the negative. But practically and actually, the mechanist 

 knows that there are many properties and phenomena of 

 life which cannot at present be explained in terms of physics 

 and chemistry, though he has faith that they may ultimately 

 be so explained. On the other hand, the vitalist knows that 

 the immediate causes of certain life processes are physical 

 and chemical, though it is always possible to assume that 

 the more remote causes are not. 



Certain simulacra of protoplasm and of cells have been 

 produced artificially, but they bear only a few resemblances 

 to the real living substance. Such artificial products show 

 that some structures and functions of living cells may be ex- 

 plained in terms of chemistry and physics, but the more we 

 know of protoplasm and cells the less likely it seems that 

 it will ever be possible to synthesize them artificially. 



For the past two or three hundred years, and ever in- 

 creasingly up to the present time, physiology has been deal- 

 ing with the chemistry and physics of living matter, and 

 especially of metabolism. Since the time of Lavoisier it 

 has been known that combustion goes on in the body, oxygen 

 being consumed and carbon dioxide given off, as in combus- 

 tion outside the body. Digestion is a chemical process which 

 can be duplicated in the laboratory. Muscular contraction 

 and even nerve conduction are accompanied by well-known 

 chemical and physical changes. No one now questions the 



