i68 INDIVIDUALITY IN ORGANISMS 



for the fundamentally quantitative character of at least 

 the main axes of the body, for if the different axes are 

 qualitatively different, I cannot conceive how the 

 position of a new head or growing tip on an isolated 

 piece can be determined in one case chiefly by the major 

 axis, in another as a resultant of two or more axes, and 

 in a third by one of the minor axes. If, however, all 

 axes are fundamentally gradients in metabolic rate, the 

 facts are very simply accounted for, as 1 have tried to 

 show. The major axis is the major axis, not because 

 its nature is fundamentally different from that of other 

 axes, but because it arises first or because its apical region 

 has the highest metabolic rate of any part of the body, 

 and the minor axes are minor axes because they arise 

 later or their apical regions have a lower rate. When 

 the major gradient is in any way obliterated to a suffi- 

 cient degree one of the minor gradients may act in 

 exactly the same way as, though often more slowly 

 than, the major gradient where it is present. This 

 is true, of course, only for forms and stages in 

 which the fundamental quantitative character of the 

 axes has not been too greatly altered by progressive 

 differentiation. 



The fact that a plant bud may be inhibited by the 

 main growing tip, by another bud, by a growing leaf, or 

 by a lateral branch also indicates that there is nothing 

 specifically different in these different inhibitions and so 

 suggests that these different plant axes act in essentially 

 a quantitative way in dominating other parts. One 

 may be substituted for the other without altering the 

 character of the effect. 



