Unicellular Organisms Like Pluricellular 59 
protoplasm to this new formation requires just as long 
as the posterior end remote from the adoral zone.?? 
This impulse to reorganization which enables proto- 
plasmic substance already organized to take on any other 
organization whatever speaks strongly in favor of the 
hypothesis that it is due to a special formative energy 
(‘“‘formgestaltenden Energie” as Nussbaum would call it) 
emanating from the nucleus, which using the proto- 
plasmic substance merely as a support or vehicle or as an 
indifferent constructive material, would be in reality the 
only quiddity which tends to dispose itself in that partic- 
ular form, which constitutes for it the only possible 
system in dynamic equilibrium. For the reasons above 
stated we must think that this formative energy is prob- 
ably nervous in nature. 
This ontogenetic function of the nucleus which we see 
in unicellular organisms permits of very important deduc- 
tions in relation to all organisms whatever. For the com- 
plicated unicellular organisms whose manifold organs 
have different and mutually independent functions, such 
as for example a Stentor coereleus or a Paramoecium 
caudatum, are not essentially different from pluricellular 
organisms, but on the contrary are comparable with them 
in all essential respects. 
“Between the internal differentiations of a complex 
cell,” says Delage, “and so between the body of certain 
Infusoria, and the organs of the pluricellular being there 
exists I think only a casual difference, which depends not 
so much on the requirements of the differentiation as on 
the size of the organism.” #4 
Gruber: Uber kiinstliche Teilung bei Infusorien. Zweite 
Mitteilung. Biol. Centralbl., Bd. V. No. 5; May 1. P. 138. 
Delage: L’hérédité et les grands problémes de la biologie gén- 
érale. P. 97. 
