INDIVIDUATION AND REPRODUCTION 227 



morphological characters themselves. As a matter of fact we 

 know that even in relatively simple chemical reactions quantitative 

 differences may very often give rise to qualitatively different results. 

 And when we recognize the very great complexity of metabolism in 

 even the simplest organism, we cannot but admit that there must 

 be many possibilities in the metabolic complex for the origin of 

 qualitative differences in characters, organs, etc., from quantitative 

 differences in metabolism. Manifestly, quality and quantity in 

 organisms are not and cannot at present be clearly distinguished. 

 That qualitative differences in the chemical constitution and 

 metabolism of different organs exist is evident, but there is at 

 present no valid evidence that such differences cannot be reduced 

 to a quantitative basis. 



DEGREES OF INDIVIDUATION 



If the organic individual consists fundamentally of one or more 

 gradients in rate of metabolism with a relation of dominance and 

 subordination between regions of higher and those of lower rate, it 

 is at once apparent that the degree of integration of such an 

 individual into a physiological unit, the degree of physiological 

 coherence and of orderly behavior, must vary widely with various 

 factors of its constitution. Since it will often be necessary in follow- 

 ing chapters to call attention to differences in the degree of indi- 

 viduation, some of these factors must be briefly considered here. 



The efficiency of conduction is a most important factor in 

 individuation. In the lower organisms and in the embryonic 

 stages of even the higher animals where the decrement in conduc- 

 tion is great, the degree of individuation is much lower than in 

 those forms or stages which possess a well-developed nervous sys- 

 tem, where the decrement is much less or almost inappreciable. In 

 the lower forms and in embryonic stages a higher metabolic rate is 

 necessary for permanent individuation; in other words, in order to 

 become or remain dominant, a given level must have a higher rate 

 of metabolism in relation to other levels than when a nervous system 

 is present. 



Another factor in individuation is the physiological stability 

 of the structural substratum. The greater the stability of the 



