The sun. [volume] (New York [N.Y.]) 1833-1916, 1897-10-31
H..

"Amixia very differently stated from that OF
Romancs's independent Variability" or Gu
lick's Independent Generation" but. appar-
emily owing 10 this difference of statement the
principle itself is not the same. Thus, although
Welsmann holds, with Romanes and Gulick.
that when new characters arise in virtue of
the nero prevention Of intercrossing with par
Ont forms. these new characters will be Of non
unitarian kinds. he appears to think that
divergence of cha actcr under such circum-
stances is not likely to 20 on TO o specific
value. 1tomancs deemed it OF Importance to OBJ
serve why Weismann arrived at this conclusion
which was not only different from that of Del.
beuf, Gulick, and Isonanes himself. but, APP
parcntly, inconsistent with his own reccgni-
ton Of the diversifying effect of 'Amixia' as
regards the formation OF permanent varieties.
In a former part OF this volume the author,
while considering Darwin views on this Same
principle of 'Amixia," shows it to be highly
inconsistent to recognize its diversifying effect
up 10 the stage OF constituting tlxeu varieties,
and then not To recognize that, SO much diver.
gcncc OF character having been already secured
by the isolation alone. much moro must
further divergence continue, and continue
at an eyer-accelerating pace. as Delbeuf
then, is the explanation of the apparent
Inconsistency on Weismann's partl Romanes
thinks that the explanation is that, owing to
his erroneous statement of the. principle. Wcis-
mann misses the real essence OF 1t. For, in tho
mrs., mrs. place, Wsismsn m does 4 is,, not perceive hat
average character on the part of the isolated
colony as compared with the rest of its species.
On the contrary. 9 loses himself in a maze OF
speculation about all species having had what
he calls variation periods" or eruptions of
gen, ral variability, alternating with periods OF
repose; both being as unaccountable in respect
of their causAtion as they are hypothetical in
i fespGGs 0I w yeisr oiEaft conciud rsof thai afSs i]so SiptGm,
OF a portion of a species Will then only lead
to divergence of character when. the isolation
IA nnHnn IN .r. MEDIA sifh "a - IA 4 tn artni "
on tn, part OF the species as a whole. and that
the divergence will cease as soon as the "varia-
Wcisinann fails to perceive that geographical
isolation Is not the only kind of isolation. or the
tercrossinE. The rcsul; Of this oversight is hit
he thinks amiXin can act but comparatively sell
com upon small Foundations suiiicienti 70 oc.
entiation OF =, ecics. In the third place, on Wing to
his ia ySri'o h.ypo!hesis that all SPECIES pass
eventually concludes that the total amount
OF divergence OF type prodncihlc by isola.
can never be greater than that betwe.n
The ex,Ecmes OF variation which occur
partition. In other words, the possibility of
change duo 10 "mixia alone is taken by Weis-
mann to be limited oy the range Of deviation
by different individual variations before the
species was divided. Thus the doctrine of
or the cumuintire nature of divergence of
type. when once such divergence, begins in a
tant, and, indeed, essential respect, Weismann's
anixia differs entirely from the principle which
h"s been severally stated by Dclbgut, Gulick.
constrained to SAY that. although Prof.
Wcismann was the first to recognize tho
dlvGrsiiying influence of indiscriminate
isolation per SC. he did so only in part. He has
failed 10 distinguish the. true essence of the
principle, and, by OVERLAPPING 1t with a mass OF
hypotheJic al speculation. concealed even more
Of 1t than he revealed. The conclusion arrived
Mt by Romanes in the book before us is that,
without ISOLATION. or thn nrnEpntInn nf FREQ in
tercrossirg. organic evolution is in no case pos
sihle. Therefore he would say OF isolation that
it has been the exclusive means of modification,
or. more correctly, the universal condition to il.
Therefore, also. h~eredity and variability being
given. the whole theory of organic evolution be-
comes a theory of the causes and conditions
which lead TO isolation.