PHYSIOLOGICAL GRADIENTS. 15! 



pattern and of still simpler patterns is of value only in the light 

 of what we can learn concerning other organismic patterns and 

 is therefore postponed (see pp. 176-178). 



The surface-interior pattern is primarily a completely radial, 

 spherically symmetrical, or centered pattern and, assuming that 

 organismic pattern arises through relation between protoplasm 

 and environment, this pattern represents such relation in its 

 most general and primitive form. While some cells and some 

 still simpler organisms may possess this pattern alone it is certain 

 that most organisms including all multicellular forms, at least 

 many unicellular forms and probably some of those simpler than 

 cells, possess not only a surface-interior pattern but also an 

 axiate or polar pattern and primarily either a radial or bilateral 

 symmetry with asymmetric modifications in various cases. Both 

 the course of organismic evolution from very early stages, as 

 well as the development of the individual, are based upon this 

 axiate pattern. I have already pointed out (pp. 149-150) that 

 the general similarities of organismic pattern in different proto- 

 plasms suggest that such pattern is, at least as regards its funda- 

 mental features, in large measure independent of the differences 

 in the specific constitution of different protoplasms and there- 

 fore essentially quantitative, i.e., it apparently represents a quan- 

 titative relation in a specific protoplasm. It now becomes neces- 

 sary to examine the data of observation and experiment with 

 reference to the question of the nature of the axiate pattern. 



Axiate Pattern.- Many different lines of evidence agree in in- 

 dicating that axiate pattern in its simplest form is essentially 

 quantitative in character and consists in graded differences in 

 the rate of the fundamental dynamic activities of protoplasm and 

 in the conditions associated with these activities. These graded 

 differences in physiological state have been called axial gradients 

 because so far as the evidence goes they are the primary indica- 

 tions of the existence of an axiate pattern (Child, 'i50- They 

 have also been called metabolic gradients, not because it is as- 

 sumed that they are purely or primarily metabolic in character, 

 but because our knowledge of protoplasm in general indicates 

 that metabolism and more specifically oxidation is a fundamental 

 factor in life and the chief source of the energy of living organ- 



