456 SUMMARY AND. CONCLUSION. 



time with the conditions which at that, or some previous time, prevail, convinced 

 that one is the formal expression of the other. We have used the same method 

 in the interpretation of organic growth. We have shown that the mere process of 

 radial and apical growth, or the aggregation of organic materials around a given 

 center, or along a given line, or surface, automatically creates regularly graded 

 zones of unlike conditions that are coincident with the distribution of unlike 

 materials or organs We conclude therefrom that the basic structure of plants 

 and animals is automatically created by the process of growth itself, or that 

 growth automatically creates special local conditions, which arc expressed in the 

 structures that appear at those points. 



The principal factors, therefore, that create organized structures arc primarily 

 internal and are sharply localized; they are the result of the environment of its 

 several parts, and they change with the process of growth. The medium external 

 to the organism as a whole, its cosmic environment, such as the sea water and its 

 contents, pressure, temperature, light, gravity, etc., is practically unaffected by 

 local growths and remains approximately constant. 



Historically speaking then, the evolution of the external environment 

 did not keep pace with the evolution of the internal environment. Primarily 

 the external environment was purely inorganic, or cosmic, broadly permissive, 

 or neutral. In the early stages of organic evolution there w r as no dependence of 

 one organism on another, no social organization, no social environment, no or- 

 ganic competition, or selection, or elimination, for all alike drew their materials 

 from the surrounding inorganic media. 



As primitive organisms became more complex, the balancing points of internal 

 environments became more precisely located, and were expressed in more stable, 

 more sharply defined differences in the structure of the resulting forms. The 

 growth of individual organisms was accelerated, or short circuited by the fusion, 

 or union, or absorption, of one form by another, giving simultaneous rise to organic 

 nutrition, sexual reproduction, social environment, and social competition. 



Thus we again reach the conclusion that the continual aggregation of like 

 units to form a homogeneous whole is an impossibility, for aggregation creates un- 

 like conditions, that create new things, new organs, new organisms, new societies, 

 and new organizations of old societies. 



II. CRISES IN ORGANIC EVOLUTION. 



The evolution of organisms does not proceed at a uniform rate, but at a 

 variable one; now slow, now fast, retreating, diverging, advancing; now by in- 

 numerable minute steps, now by leaps and bounds; because the ever shifting 

 relations of part to part, organ to individual, and individual to society, are of 

 unlike nature and of unequal value. 



These inequalities in the potential value of organic readjustments form the 

 true basis of a natural system of classification. They create the critical periods 

 in organic evolution; they produce actual gaps in the mosaic of adult forms which 



