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 observations upon the 
influence which the nervous system exercises upon de- 
velopment and regeneration.*® 
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 tiber die Beziehung des Nervensystems zur 
Regeneration bei Amphibien. Archiv f. Entw.-Mech. d. Org., Bd. 
XVI, Heft 1; March 13, 1903;—Kurt Goldstein: Kritische und ex- 
perimentelle Beitrage zur Frage nach dem Einflug des Zentralner- 
vensystems auf die embryonale Entwicklung und die Regeneration. 
Arch. fiir Entw.-Mech. d. Org., Bd. XVIII, Heft 1; February 26, 
1904 ;—Eugenio Rignano: Die zentroepigenetische Hypothese und der 
Einflug des Zentralnervensystems auf die embryonale Entwicklung 
und die Regeneration, Arch. f. Entw.-Mech. d. Org., Bd. XXI, Heft. 
4; September 11, 1906 
