132 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



equipotential system may cover a very great area that, in 

 fact, it is a scheme of a very wide extent. 



The Problem of the Factor E 



We turn back again to considerations of a more abstract 

 form. We left our analysis of the differentiation of the 

 harmonious-equipotential systems, and particularly of the 

 phenomena of localisation during this differentiation, at the 

 point where we had succeeded in obtaining an equation 

 as the expression of all those factors on which the pro- 

 spective value, the actual fate, of any element of our 

 systems depends, p.v. (X) =/ (s, I, E) was the short ex- 

 pression of all the relations involved ; s and /, the absolute 

 size of the system and the relative position of the element 

 with respect to some fixed points, were independent variables ; 

 E was a constant, namely, the prospective potency, with 

 special regard to the proportions embraced by it. 



We shall now study the significance of the factor E. 



What does this E mean ? Is it a short expression 

 merely for an actual sum of elemental agents having a 

 common resultant ? And, if so, of what kind are these 

 agents ? Or what may E mean, if it can be shown not to 

 be a short sign for a mere sum ? 



No Explanation Offered by " Means " or " Formative Stimuli ' 



For practical purposes it seems better if we modify the 

 statement of our question. Let us put it thus : E is one 

 of the factors responsible, among variables, for the localisa- 

 tion of organic differentiation ; what then do we actually 

 know about the causal factors which play a localising part 



