178 INDIVIDUALITY IN ORGANISMS 



The question whether metabolic gradients involving 

 different metabolic processes may exist at the same time 

 in the same protoplasm must at least be raised. So far 

 as gradients depending on transmission are concerned, 

 this question is really the question whether different 

 sorts of changes or excitations may be transmitted 

 through the same protoplasm and whether different 

 metabolic effects result. Any answer to this question 

 at present is little more than a guess. It is perhaps 

 conceivable that at least in undifferentiated or slightly 

 differentiated protoplasm some degree of difference in 

 the character of the transmitted change may exist under 

 different conditions of excitation, etc. If such differ- 

 ences do exist, they must of course be important factors 

 in development and differentiation, but they merely 

 complicate and do not alter fundamentally the character 

 of unity and order in the individual. At present there 

 seems to be no real evidence that they exist. 



THE NATURE OF INHIBITION 



In chaps, iv and v, I have pointed out that the 

 inhibition or retardation of new individuation by the 

 dominant region of an individual occurs when the origi- 

 nal gradient is sufficiently fixed in the protoplasm, or the 

 metabolic rate at the levels concerned is sufficiently high 

 to prevent the establishment of a gradient in another 

 direction or to obliterate more or less completely or 

 prevent the further development of a gradient in another 

 direction. In Tubularia the inhibiting influence of the 

 apical region on the development of a hydranth at the 

 basal end of a piece is apparently simply the obhterating 

 effect of the original gradient on the gradient in the 



