74 Indications of a Central Zone of Development 
descendant organism, to the definite function of develop- 
ment, and which differentiates itself gradually from the 
other parts of this tissue by quite inappreciable and 
gradual transitions. 
We have already said that the centroepigenetic 
hypothesis makes it necessary to distinguish the effective 
germinal zone, or true place of origin of the germinal 
substance, from the apparent germinal zone, which would 
be nothing else than the receiving station for the sub- 
stance separated out or secreted by the effective germinal 
zone, or the place where the sexual cells concerned are 
built up out of this material. While we must regard only 
the effective germinal zone as the central zone of develop- 
ment, it is clear that the apparent germinal zone can be 
located at any part whatever of the organism. 
In the higher plants the apparent germinal zone of the 
asexual budding cells, and that of the female, sexual cells, 
would seem generally to coincide approximately with the 
actual zone, that is, with the corresponding central zone 
of the leaf and of the flower. 
In this way can be explained the heretofore puzzling 
phenomenon of the Xenia, in which as is known the 
flower after a hybrid fecundation, often takes on the 
form, size, color and tissue structure, characteristic of the 
variety from which the pollen comes; that is, as Darwin 
has already observed “in which the male element not 
only influences the germ as is its proper function, but 
at the same time influences various parts of the mother 
plant, in the same manner as it influences the same parts 
in the seminal offspring from the same two parents.” 47 
47Darwin: The Var. of Animals and Plants under Domestication. 
Eighth impression of the second edition. Vol, I. London, Murray, 
1882. Chap. XI, P. 433. 
