CLASSIFICATION OF LIVING TYPES 57 



where there is building up of them, there also is as- 

 similation, if these constituent particles form part of 

 an individual whole when that individual is in a stage 

 of growth. But no diffusion occurs either way if 

 the individual is in a perfectly steady state of 

 motion or of rest. It is this diffusion of the con- 

 stituent particles in a group when in an unsteady 

 state of motion that constitutes the fundamental 

 principle which, even in its most elementary state, 

 we may associate with vital energy. 



Metabolism is, therefore, a phenomenon of a higher 

 order than mere disintegration, which forms a 

 necessary part of it. It is, in fact, the actual combi- 

 nation in the same body or group of particles of 

 two rival processes ; of construction and destruction, 

 or of growth and of decay. It is therefore the 

 combination of two mutually contradictory effects ; 

 contradictory in so far as they occur in the same 

 group or aggregate of particles, but not as actually 

 occurring in the same individual particle at the same 

 time. And as in the higher grades, in the radiobe for 

 instance, the individual is the product of two different 

 bodies, the gelatin on the one hand, and the radium 

 on the other, so even in the simplest cases of meta- 

 bolic action there are to be found the same, or similar, 

 combinations of two totally different modes of molec- 

 ular action. In one terminology, of association and 

 dissociation : in another, nomenclature, of the build- 

 ing up and breaking down of little systems whether 

 molecular or atomic. How then does it come to pass 

 that these systems are built up ? We can understand 

 without much difficulty how it should be that, having 



