76 Hypothesis of Structure of Germ Substance 



zone is almost self-evident from what has preceded, and 

 will be still more so from what is to follow. Here it may 

 only incidentally be remarked, (since we have treated of 

 the subject more thoroughly in another place), that this 

 hypothesis concerning the location of the central zone in 

 vertebrates, and in general in those animals which have 

 a specialized nervous system, finds a very strong support 

 also in the numerous researches and obseryations upon the 

 influence which the nervous system exercises upon de- 

 velopment and regeneration. 49 



From this we can now pass on to the discussion, even 

 though very briefly, of the question of the probable com- 

 position and structure of the substance which constitutes 

 this zone, and which is consequently none other than the 

 germinal substance. This affords an opportunity of 

 speaking of the not essential but subordinate difference by 

 which the germinal nuclei are probably distinguished from 

 the somatic. 



2. Hypothesis Upon the Structure of the Germinal 



Substance 



We have seen that according to the centroepigenetic 

 hypothesis, ontogeny can be attributed to a series of mod- 



*See e. g. Wolff: Die physiologischen Grundlagen der Lehre 

 von den Degenerationszeichen. Virchows Archiv, Bd. 164, 1902; 

 Richard Rubin : Versuche iiber die Beziehung des Nervensystems zur 

 Regeneration bei Amphibien. Archiv f. Entw.-Mech. d. Org., Bd. 

 XVI, Heft i ; March 13, 1903 ; Kurt Goldstein : Kritische und ex- 

 perimentelle Beitrage zur Frage nach dem Einflu/3 des Zentralner- 

 vensystems auf die embryonale Entwicklung und die Regeneration. 

 Arch, fur Entw.-Mech. d. Org., Bd. XVIII, Heft i; February 26, 

 1904; Eugenic Rignano: Die zentroepigenetische Hypothese und der *, 

 EinflujS des Zentralnervensystems auf die embryonale Entwicklung 

 und die Regeneration, Arch. f. Entw.-Mech. d. Org., Bd. XXI, Heft. 

 4; September n, 1906 



