534 Vehicles of the Hereditary Characters. 
whom the character of every species constitutes an in- 
separable whole and every material vehicle, therefore, 
represents the sum of all its qualities. The adherents 
to this view are still in the majority. It is the very 
opposite of DARWIN'S view, according to which the indi- 
vidual cells of the organism and the individual compo- 
nent elements within the cells each have their special 
representatives in the hereditary substance. Thus the 
material basis of inheritance is composed of as many 
different units as there are separate organs and types 
of cells. 
NAGELI has introduced the word idioplasma for this 
material basis ; and for many reasons this term should 
be universally employed, especially since it can be used 
in speaking of the two opposite theories. To NAGELI 
the idioplasm was a unit, but we may, as well, apply this 
term to the sum total of DARWIN'S units. 
The independent behavior of the individual hereditary 
characters both in the process of mutation and in hybridi- 
zation, definitely proves, in my opinion, the correctness of 
DARWIN'S assumption of separate material bases for 
each one of them ; and the whole contrast between muta- 
bility and fluctuating variability can only be brought into 
harmony with the theory in the light of this principle. 1 
DARWIN'S pangenesis may be summarized in the two 
following theses. 2 
The individual cells and organs of the whole organ- 
ism are represented in every germ cell and every bud by 
1 The correctness of this view receives strong- support from the 
fact that those of my critics who are partisans of WALLACE'S form 
of the theory of selection, simply deny the distinction between muta- 
bility and fluctuating variability. See above, p. 599. 
2 DARWIN, Animals and Plants under Domestication, Vol. TT, 
Chapter on Pangenesis; and my Intracellular Pangenesis (Engl. ed.), 
pp. 5 and 60. 
