216 A. J. Loika — Mode of Growth of Material Aggregates. 



reaction, are accessible to individual observation ; and it is hoped 

 on a future occasion to prosecute the work further in this 

 direction. 



For the present, however, we will conclude with a brief sum- 

 mary of the main points developed so far : 



1. We have recognized the problem of chemical dynamics 

 as a special case of a wider problem ; The former is the study 

 of the laws governing the changes in the distribution of matter 

 among different chemical compounds, as determined mainly by 

 their chemical character; the latter is the study of the laws 

 governing the distribution of matter among complexes of any 

 specified kind, as determined by -their general physical character. 



The statement of the wider problem may be taken to repre- 

 sent the quantitative formulation of the problem of evolution 

 in its most general terms. 



2. We have illustrated a statistical method which is suffi- 

 ciently general in its application to comprise such widely differ- 

 ent cases as that of the growth of a population under certain 

 simple conditions, on the one hand, and that of a simple chem- 

 ical equilibrium reaction, on the other. The fundamental 

 feature of this method is the splitting up of the characteristics 

 governing the rate of growth of a material aggregate into two 

 factors — the one relating to those properties of the system which 

 determine the formation of new individuals, and the other 

 relating to those properties of the system which determine the 

 limitation of the " life period " of the individual constituents. 



3. Incidentally Ave have suggested a physical conception of 

 the character of chemical action, of the " passive resistance " 

 which checks its velocity, of catalytic action, of the "nascent" 

 state, and of tautomerism. 



