THE ORIGIN OF LIFE. 31 



this general unification. It is certainly in a line with 

 this advance to reach a mechanical view of this life 

 essence. If, therefore, a mechanical explanation is 

 possible, there is good reason for believing that it is 

 in the line of truth. 



The mechanical theory is, in brief, that the direc- 

 tive conditions of which we are in search are simply 

 those of chemical composition and molecular ar- 

 rangement. It is pointed out that the properties 

 of compounds increase in complexity with the in- 

 crease of the complexity of the compounds, that as 

 the molecule becomes more complicated its powers 

 and possibilities become more diversified. The prop- 

 erties of compounds have, moreover, no traceable 

 relation to the properties of the elements from which 

 they are made. Oxygen and hydrogen, when they 

 unite, form water, a compound with properties not 

 possessed by either of the elements ; and yet we do 

 not doubt that they are due to the properties of the 

 elements. It is therefore easy to make the far- 

 reaching assumption that,- when the molecule be- 

 comes as complicated as that of protoplasm, its 

 properties will be as complicated as those of living 

 things. One of these properties is to induce chemi- 

 cal changes in foods. Just as it is the property 

 of water to dissolve many chemical substances, so 

 it is the property of the highly complex body pro- 

 toplasm to cause chemical changes. When it is 

 possible, we are told, to manufacture the chemical 

 substance protoplasm, it will of necessity be alive, 

 for there are no peculiar powers in organisms not 

 inherent in them as the result of molecular arrange- 



