222 SCIENCE AND PHILOSOPHY OF THE ORGANISM 



our choice. Without regarding here the exact order of 

 the regeneration phenomena, which is almost unknown at 

 present, we in any case can say without any doubt that 

 the line of consecutive possible cross -sections forms a 

 complex-morphogenetic system, as every one of them is 

 able to give rise to a complex organ, viz. the foot and part 

 of the leg. It is an open question whether this complex 

 system is to be called " equipotential " or not. It indeed 

 seems to be inequipotential at the first glance, for each 

 single section has to form a different organogenetic totality, 

 namely, always that specific totality which had been cut 

 off; but if we assume hypothetically that the real " Anlage " 

 which is produced immediately by the cells of the wounded 

 surface is the very same for all of them, and that it is the 

 actual state of organisation which determines to what result 

 this Anlage is to lead, 1 we may say that the series of con- 

 secutive cross-sections of a newt's leg does form a morpho- 

 genetic system of the complex-equipotential type, promoting 

 secondary regulations of form. 



Xow all these difficulties vanish, if we consider the 

 regeneration of animals, such for instance as many worms 

 of the annelid class or our familiar ascidian Clavellina, in 

 which regeneration in both directions is possible. The 

 wound at the posterior end of the one half which results 

 from the operation forms a posterior body half, the wound 



1 A full " analytical theory of regeneration " has been developed elsewhere 

 (Organ. ReguL p. 44, etc.). I can only mention here that many different 

 problems have to be studied by such a theory. The formation of the 

 "Anlage" out of the body and the differentiation of it into the completely 

 formed results of regeneration are two of them. The former embraces the 

 question about the potencies not only of the regenerating body but of the 

 elements of the Anlage also ; the latter has to deal with the specific order 

 of the single acts of regenerative processes. 



