THE MECHANISTIC CONCEPTION 11 



favorable to the mechanistic or physicochemical 

 view of life. It is possible to consider here only a 

 small number of these facts, and it seems best to think 

 of these in relation to the most obvious differences 

 that exist between the animal mechanism and the 

 organized products of human inventiveness. If we 

 think of our evidence in this way, we shall be better 

 able to perceive the strength or weakness of the 

 mechanistic conception. There are four properties 

 of living organisms which distinguish them with 

 the utmost clearness from even the most complex 

 mechanisms of human make. These properties are, 

 first, the peculiar chemical constitution of the basic 

 material or protoplasm of which the living cells are 

 composed; secondly, the powers of metabolism or 

 simultaneous upbuilding and breakdown of the 

 living protoplasm; thirdly, the power of reproduc- 

 tion ; and, finally, the power of growth and all that 

 this implies in respect to a regulative influence over 

 the living material. 



Let us consider, first, the known physical and 

 chemical properties of the living protoplasm. This 

 useful term bridges immense chasms in our knowl- 

 edge. The substance which fills the living cells 

 has no uniformity of physical or chemical constitu- 

 tion, for it varies considerably hi different kinds of 

 cells. But it has certain distinctive properties which 

 stand in the most intimate relation to the things 

 which living cells do. Both the physical and chemi- 

 cal properties of protoplasm are in the main due to 



