EXPERIMENTAL MORPHOGENESIS 121 



will occur in the whole system ; it is to this single part 

 that the term " function of the position " relates. We 

 therefore might call our systems equipotential systems with 

 single potencies ; or, more shortly, singular-equipotential 

 systems. 



But even this terminology would fail to touch precisely 

 the very centre of facts: it is not only the simplicity 

 or singularity of their potencies which characterises the 

 role of our systems in morphogenesis, 1 but far more im- 

 portant with respect to the production of form are two 

 other leading results of the experimental researches. The 

 proper act to be performed by every element in each actual 

 case is in fact a single one, but the potency of any element 

 as such consists in the possibility of many, nay of indefinitely 

 many, single acts : that then might justify us in speaking of 

 our systems as " indefinite equipotential," were it not that 

 another reason makes another title seem still more prefer- 

 able. There are indeed indefinite singular potencies at 

 work in all of our systems during ontogeny : but the sum 

 of what happens to arise in every case out of the sum of 

 the single acts performed by all of the single equipotential 

 cells is not merely a sum but a unit ; that is to say, there 

 exists a sort of harmony in every case among the real 

 products of our systems. The term harmonious-equipotential 

 system therefore seems to be the right one to denote them. 



We now shall try first to analyse to its very extremes 

 the meaning of the statement that a morphogenetic system 

 is harmonious-equipotential. 



1 The name of singular-equipotential systems might also be applied to 

 elementary organs, the single potencies of which are awaked to organogenesis 

 by specific formative stimuli from without ; but that is not the case in the 

 systems studied in this chapter. 



