1 98 SCIENCE PROGRESS 



cease to follow the law of definite combining weights which is 

 the basis of chemistry. The quantity of the substance A which 

 will combine with a fixed quantity of the substance B is deter- 

 mined not only by the chemical nature of A and of B, but also 

 by the chance conditions of temperature and concentration of 

 the moment. This class of chemical compounds is within limits 

 continuously adjustable to changes in its surroundings, while at 

 the same time it resists those changes by reason of its inertia. 

 Here is a real adumbration in non-living matter of the chemical 

 flux which is the abiding characteristic of the matter of life. 



The biologist speaks of these molecular complexes as molecules, 

 and in that he is wrong in so far as the word implies a defined 

 structure, a chemical unit. The biogen, or chemical unit of 

 living matter, is not a fixed unit like the molecule of dead 

 proteid ; it is an average state. That we know from the 

 chemical phenomena of living matter. 



Why should this be ? Consider what must happen if you 

 make the atomic building much larger than it already is in the 

 molecule of dead proteid. You already have a molecule so 

 large as to be liable to fracture on mere mechanical agitation. 

 A molecule composed of fifty proteid molecules would cease to 

 be a molecule in the physical sense : it would be matter in mass, 

 defined by a surface ; it would break up the waves of light, so 

 radiant energy would profoundly affect it. 



In a mass so large, a portion of the energy would of necessity 

 be in a borderland between what we call osmotic energy and 

 surface energy, the fraction in the one state or the other being 

 determined from moment to moment by the changing relations 

 with the enveloping matter. If the chemical structure was such 

 as to produce a shape other than a sphere, surface energy would 

 tend to produce chemical rearrangements, and the opposing play 

 of these forces might result in oscillations of form which would 

 reflect the irregular flux of cosmical forces just as does the 

 particle in Brownian movement. The chemical relations of such 

 a mass would be defined in the first instance by the surface 

 layer, but any simple chemical event on the surface would be 

 likely to fire a train of events leading to an eruption like a sun- 

 spot on the sun. 



It is not, I think, difficult on these lines to conceive of a 

 substance the chemical units of which could maintain themselves 

 only in virtue of a'continual flux of matter and energy — only, that 



