220 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



unities consisting of elements equal in morphogenetic 

 faculty) may also be the basis of restitution processes. 

 Whilst in the harmonious system the morphogenetic acts 

 performed by every single element in any actual case are 

 single acts, the totality of all the single acts together forming 

 the harmonious whole, in the other type of systems now to 

 be examined, complex acts, that is, acts which consist of a 

 manifoldness in space and in time, can be performed by 

 each single element, and actually are performed by one or 

 the other of them. We therefore have given the title of 

 " complex-equipotential systems " to the systems in question, 

 as all our denominations are based on the concept of the 

 prospective morphogenetic potency, that is of the possible 

 fate of the elements. 



The cambium of the Phanerogams may be regarded as 

 the very type of a complex-equipotential system, promoting 

 restitution of form. It runs through the whole stem of 

 our trees, in the form of a hollow tube, placed between 

 the inner and the outer cell-layers of the stem, and either 

 branch or root may originate from any single one of its 

 cells, just as circumstances require. We might call the 

 cambium a system of the " complex " type of course, even 

 if every one of its constituents were able to form only a root 

 or only a branch by way of restitution. But in fact one 

 and the same element can form both of these complex- 

 structures ; it depends only on its relative position in the 

 actual part of the stem isolated for the purposes of experi- 

 ment, what will be accomplished in every case. Here we 

 have a state of affairs, which we shall encounter again 

 when studying regeneration in animals : every element of 

 the system may be said to contain potencies for the " ideal 



