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a single； or even in several generations； is nevertheless capable of
being accumulated in successive generations till it amounts to
specific and generic difference。 I have found the first point as
much as I can treat within the limits of this present article； and
will avail myself of the hospitality of the Universal Review next
month to deal with the second。
The proposition which I have to defend is one which no one till
recently would have questioned； and even now； those who look most
askance at it do not venture to dispute it unreservedly； they every
now and then admit it as conceivable； and even in some cases
probable； nevertheless they seek to minimise it； and to make out
that there is little or no connection between the great mass of the
cells of which the body is composed； and those cells that are alone
capable of reproducing the entire organism。 The tendency is to
assign to these last a life of their own； apart from； and
unconnected with that of the other cells of the body； and to cheapen
all evidence that tends to prove any response on their part to the
past history of the individual； and hence ultimately of the race。
Professor Weismann is the foremost exponent of those who take this
line。 He has naturally been welcomed by English Charles…Darwinians；
for if his view can be sustained； then it can be contended that use
and disuse produce no transmissible effect； and the ground is cut
from under Lamarck's feet； if； on the other hand； his view is
unfounded； the Lamarckian reaction； already strong； will gain still
further strength。 The issue； therefore； is important； and is being
fiercely contested by those who have invested their all of
reputation for discernment in Charles…Darwinian securities。
Professor Weismann's theory is； that at every new birth a part of
the substance which proceeds from parents and which goes to form the
new embryo is not used up in forming the new animal； but remains
apart to generate the germ…cellsor perhaps I should say 〃germ…
plasm〃which the new animal itself will in due course issue。
Contrasting the generally received view with his own； Professor
Weismann says that according to the first of these 〃the organism
produces germ…cells afresh again and again； and that it produces
them entirely from its own substance。〃 While by the second 〃the
germ…cells are no longer looked upon as the product of the parent's
body； at least as far as their essential partthe specific germ…
plasmis concerned； they are rather considered as something which
is to be placed in contrast with the tout ensemble of the cells
which make up the parent's body； and the germ…cells of succeeding
generations stand in a similar relation to one another as a series
of generations of unicellular organisms arising by a continued
process of cell…division。〃 ｛30｝
On another page he writes：…
〃I believe that heredity depends upon the fact that a small portion
of the effective substance of the germ； the germ…plasm； remains
unchanged during the development of the ovum into an organism； and
that this part of the germ…plasm serves as a foundation from which
the germ…cells of the new organism are produced。 There is；
therefore； continuity of the germ…plasm from one generation to
another。 One might represent the germ…plasm by the metaphor of a
long creeping root…stock from which plants arise at intervals； these
latter representing the individuals of successive generations。〃 ｛31｝
Mr。 Wallace； who does not appear to have read Professor Weismann's
essays themselves； but whose remarks are； no doubt； ultimately
derived from the sequel to the passage just quoted from page 266 of
Professor Weismann's book； contends that the impossibility of the
transmission of acquired characters follows as a logical result from
Professor Weismann's theory； inasmuch as the molecular structure of
the germ…plasm that will go to form any succeeding generation is
already predetermined within the still unformed embryo of its
predecessor； 〃and Weismann；〃 continues Mr。 Wallace； 〃holds that
there are no facts which really prove that acquired characters can
be inherited； although their inheritance has； by most writers； been
considered so probable as hardly to stand in need of direct proof。〃
｛32｝
Professor Weismann； in passages too numerous to quote； shows that he
recognises this necessity； and acknowledges that the non…
transmission of acquired characters 〃forms the foundation of the
views〃 set forth in his book； p。 291。
Professor Ray Lankester does not commit himself absolutely to this
view； but lends it support by saying （Nature； December 12； 1889）：
〃It is hardly necessary to say that it has never yet been shown
experimentally that ANYTHING acquired by one generation is
transmitted to the next （putting aside diseases）。〃
Mr。 Romanes； writing in Nature； March 18； 1890； and opposing certain
details of Professor Weismann's theory； so far supports it as to say
that 〃there is the gravest possible doubt lying against the
supposition that any really inherited decrease is due to the
inherited effects of disuse。〃 The 〃gravest possible doubt〃 should
mean that Mr。 Romanes regards it as a moral certainty that disuse
has no transmitted effect in reducing an organ； and it should follow
that he holds use to have no transmitted effect in its development。
The sequel； however； makes me uncertain how far Mr。 Romanes intends
this； and I would refer the reader to the article which Mr。 Romanes
has just published on Weismann in the Contemporary Review for this
current month。
The burden of Mr。 Thiselton Dyer's controversy with the Duke of
Argyll （see Nature； January 16； 1890； et seq。） was that there was no
evidence in support of the transmission of any acquired
modification。 The orthodoxy of science； therefore； must be held as
giving at any rate a provisional support to Professor Weismann； but
all of them； including even Professor Weismann himself； shrink from
committing themselves to the opinion that the germ…cells of any
organisms remain in all cases unaffected by the events that occur to
the other cells of the same organism； and until they do this they
have knocked the bottom out of their case。
From among the passages in which Professor Weismann himself shows a
desire to hedge I may take the following from page 170 of his book：…
〃I am also far from asserting that the germ…plasm which； as I hold；
is transmitted as the basis of heredity from one generation to
another； is absolutely unchangeable or totally uninfluenced by
forces residing in the organism within which it is transformed into
germ…cells。 I am also compelled to admit it as conceivable that
organisms may exert a modifying influence upon their germ…cells； and
even that such a process is to a certain extent inevitable。 The
nutrition and growth of the individual must exercise some influence
upon its germ…cells 。 。 。 〃
Professor Weismann does indeed go on to say that this influence must
be extremely slight； but we do not care how slight the changes
produced may be provided they exist and can be transmitted。 On an
earlier page （p。 101） he said in regard to variations generally that
we should not expect