THEORIES OF INDIVIDUALITY 39 



to that of a. Every other point in the mass, so far as it 

 is within the limit of effectiveness of both a and b, will be 

 subordinate to both to a greater or less degree, and its 

 metabolic condition will be the resultant of its position 

 in the two gradients. Such an organism possesses not 

 only a polar axis or gradient, but an axis or gradient of 

 symmetry as well, and in the same way other gradients 

 and other relations of dominance and subordination 

 may arise. Obviously it is possible for various gradients 

 to exist simultaneously in a living mass, and their rela- 

 tions may be very different in different cases, as are the 

 relations between the different axes in organisms. Inter- 

 ference between different gradients in opposite or nearly 

 opposite directions, or obliteration of one gradient by 

 another of higher rate of reaction, undoubtedly occurs, as 

 following chapters will show, but their relations need 

 not be considered here. 



The physiological dominance of one part over another 

 is certainly not a constant, unchanging relation, but 

 depends upon the metabolic rate in the dominant apical 

 region and the conductivity of other regions. The meta- 

 bolic rate in the dominant region is also not constant, 

 but must fluctuate with changes in external conditions. 

 With a slight rise in metabolic rate in the dominant 

 region its influence on other regions is slight and does 

 not extend far, but when the increase is great the degree 

 of dominance is greater and extends to a greater distance. 

 Certainly in the primitive individual these relations must 

 be regarded as constantly undergoing change in degree 

 and extent, though under the usual conditions they must 

 also show a general average. So for each level there will 

 be a general average of the effect of the transmitted 



