Evolution and Epigenesis 105 
We note that theoretically a mixed or intermediate 
hypothesis would be conceivable, according to which a 
given part of the organism would be differentiated 
through the cooperation of causes lying within and with- 
out it. Incase however the causes lying at any moment of 
ontogeny within the part concerned, do not arise through 
any antecedent process of epigenetic nature, the develop- 
ment at least up to this time must be considered as essen- 
tially purely evolutionary. But if, on the contrary, the 
internal causes do arise through an antecedent process of 
epigenetic nature the whole development would then be 
essentially of that nature. 
Whitman states that the conception of modern evo- 
lutionists differs essentially from that of the earlier ovists 
and spermatists; for they excluded the formation of new 
structural parts during development, a thing which is nat- 
urally admitted by the evolutionists of to-day. Accord- 
ing to Mivart’s definition which Whitman accepts com- 
pletely, “the term evolution may be employed, as it has 
been, to denote that the successive formation of parts pre- 
viously not existent is due not to their imposition from 
without but to their generation from within.” ‘° 
According to this definition which is essentially iden- 
tical with that of Roux above cited, evolution, it may 
here be repeated, limits to a minimum the influence which 
the various other parts of the organism exert upon the 
development of each part, or considers it as absolutely 
non-existent, since each part contains within itself, or in 
any event in its immediate neighborhood, the causes of its 
progressive development. According to the epigenetic 
Whitman: Evolution and Epigenesis. Biol. Lect. at the Mar. 
Biol. Lab. of Woods Holl, Summer Session 1894. Boston, U. S. A., 
Ginu, 1896. P. 224. 
