92 Hypothesis of Structure of Germ Substance 
different species the result of the graft is not certain 
and often unfavorable. 
This can be explained by the fact that in numerous 
species of plants, as we have seen, nearly all the cells 
preserve the reproductive capacity. What one calls 
“vegetative affinity’ is then perhaps nothing else than 
a direct effect of the retention of the whole of the 
specific germinal potential elements in addition to the 
somatic elements peculiar to each of the different tissues, 
in all or nearly all the different nuclei which do not 
pass beyond a certain degree of differentiation. 
In drawing a conclusion from all that has been said 
so far, we are confronted with this apparent paradox: 
on the one side, it seems that in conformity with the 
epigenesists we must reject a nuclear division which 
during one and the same development must be 
sometimes qualitatively equal, sometimes unequal, as 
inadmissable and refuted by the facts, and instead of 
this admit only a nuclear division always qualitatively 
equal. On the other hand it appears that in conformity 
with the preformists, one must likewise exclude a nuclear 
substance, identical in all the cells of the same organism, 
and must accept on the contrary, the hypothesis of an 
actual nuclear somatization. It follows that this nuclear 
somatization can be effected only gradually and only by 
a process of epigenetic nature. 
But when one has once admitted equal nuclear divis- 
ion and gradual nuclear somatization by a process of 
epigenetic nature, there follows therefrom necessarily the 
hypothesis of centroepigenesis. For if the nuclei of the 
cells of the different tissues of the body finally become 
completely somatized it is certain that some certain ones 
of the nuclei constituting the organism do not become 
