Child, Driesch's harmonic equipoteutial systems iu form-regulation. (321 



far known a minimal size exists, below which no piece is capable 

 of forming- a whole. Dries eh is of course perfectly familiar with 

 this fact, but it plays no part in his general conclusions concerning 

 these systems. But the existence of such a minimal size-limit is 

 of itself a very strong argument for the existence of an „extensive 

 Mannigfaltigkeit" i. e., a „machine" as the basis of the processes 

 leading to the formation of a new whole. It should also be noted 

 that the minimal size-limit is not determined solely by the amount 

 of material present. It may differ widely in different regions of 

 the body: in Planaria, for instance, minimal pieces from certain 

 regions are several times as large as those from other regions and 

 I have found that the size of the minimal piece differs with age 

 (these results are not yet published). In Tubularia also (Child, 

 1907 f) the size of minimal pieces differs considerably in different 

 regions of the body, being much less in proximal than in distal 

 regions. 



Moreover, in certain cases, e. g., in Planaria, axial hetero- 

 morphosis is particularly characteristic of certain regions of the body, 

 and the same is true, though in less degree of Tubularia. Such 

 facts as these cannot be ignored or interpreted as mere incidents 

 in any consistent and logical hypothesis of regulation. 



Dries ch's second „proof" of „Lebensautonomie" is as follows: 

 „Eine nach den drei Dimensionen typisch spezifisch verschiedene 

 Maschine bleibt nicht ganz, w^enn sie geteilt wird, deshalb liegt der 

 Genese äquipotentieller Systeme mit komplexen Potenzen im Be- 

 reiche des Formbildungsgeschehens kein maschinelles, chemisch- 

 physikalisches Geschehen zugrunde" (Driesch, 1903, p. 74). This 

 „proof" is also given in later works (Driesch, 1904, pp.116 — 118; 

 1905 a, pp. 208—211). 



This is open to the same objections as the first: the original 

 machine in the organism does not remain the same when it is 

 divided, but the act of division results under certain conditions 

 in the realization of a new machine which previously existed only 

 as a potence or possibility. 



Dries ch^s argument for „beinahe unendliche" complexity of 

 the machine which, according to the mechanistic hypothesis, must 

 underlie the phenomena of „normal" development (Driesch, 1904, 

 p. 115; 1905 a, pp. 206—207) also fails to take account of the fact 

 that the complexity is largely potential at the beginning of deve- 

 lopment and is therefore not necessarily represented at that time 

 by a corresponding „typische chemisch-physikalische Spezifitäts- 

 kombination". Herbst's conclusion that „wir sind also nicht im- 

 stande, nachzuweisen, dass die Zahl der Verschiedenheiten im An- 

 fange der Entwickelung geringer ist als die Gesamtzahl der im 

 Laufe der Ontogenese stattfindenden Differenzierungsprozesse; d. h. 



