350 THE AMERICAN NATURALIST [Vol. LI 



tion only when the details of all systems are made clear, 

 but the security of the principles themselves is affected 

 scarcely at all by this analysis. * 



I do not claim that the enzyme theory of life possesses 

 a general basis as adequate, for example, as that of the 

 principle of least action. I do claim, however, that this 

 is because the latter can be stated in terms of an exact 

 mathematical formula, whereas the enzyme theory has to 

 be given a qualitative description. The enzyme doctrine 

 is supported at the present time by a considerable number 

 of specific facts of cell chemistry, but it possesses a far 

 more substantial bulwark in the general facts of vital 

 function. Shall we deny that these facts are adequately 

 established, or that they are important, or that they merit 

 explanation? Shall we reject a definite physico-chemical 

 conception which at one stroke explains the majority of 

 the mass relationships of living matter, on the ground 

 that the details of some special life-processes have not yet 

 been described in terms of this conception? Or is it 

 preferable to preserve the inexplication of these same 

 generalities to furnish a basis for vitalism? 



There are an indefinitely large number of ways in which 

 the principle of the conservation of energy can be exem- 

 plified in special pieces of machinery, and there are just 

 as many ways in which the principle of specific catalysis 

 can operate. Instead of holding the energy principle in 

 abeyance until we have seen how the action of a special 

 mechanical system can be explained in terms of it, we 

 usually assume it to be true, and shortly find the action 

 in question very easy to understand. This would seem to 

 be the only feasible method for employing any theoretical 

 proposition, even if it is merely a novel working hypoth- 

 esis. The trouble which arises in the attempt to apply the 

 enz}Tne theory to specific problems is a normal result of 

 the inertia of the human imagination, which does not im- 

 mediately outline a plan for a machine to accomplish a 

 definite purpose, even when it is provided with all of the 

 principles of mechanics. Surely, however, the plan can 

 never be developed if such principles are neglected. 



