The sun. [volume] (New York [N.Y.]) 1833-1916, 1893-10-15

II IL tChuOWtoubou Uy WelnSmnnn tnny 01I
ferent forms OF unicellular organisms orig
mated as 80 many results Of differences in the
direct action OF the environments Consequent
". according to the theory, all congenita
variations which now occur In muticellulai
organisms are really tho remote results Of
variations that were originally induced in their
unicelular ancestors by the direct action OF
surrounding conditions OF life. That Is to say,
the Lamarckian factors OF use and dIsuse are
operative In the case Of all unicellular organ
isms. and only cease to operate upon such as
become multicellular.
We have here q summary OF welssmann's
theory as II was originally propounded
before he made certain qualifications
which 1t Will be convenient to consider
hereafter In connection with the criti-
csm OF his doctrine. Meanwhile. as even
the above description concentrates the sub
stance OF several volumes. 1t may be well to
follow Mr.. Romanes in his effort to set forth
the Weissmann hypothesis. or rather elaborate
structure OF hypothesis. within the com pass Of
single paragraph. At oil events. the main
features OF tho theory may DO pack ed
In nutshell. thus: Living material Ia
essentially or OF its own nature imperish-
| able. and 1t still continues to DO so In
tho cnse OF unicellular organisms which
propagate by fssion or gemmation. But
us soon as these primitive methods OF propa-
cation became. from whatever cause. super
seeded by sexual methods. it ceased to be for
the benefit OF species that their constituent
| individuals should be immortal: seeing that.
| IL they continued to be So all species Of sexu-
| ally reproducing organisms would sooner or
! later come to be composed OF broken down
and decrepit individuals. Consequently. In
all sexually reproducing or multccllulnr Or
ganisms natural selection set to work to
reduce the term OF individual lfctlmes
within the narrowost limits that in the
case OF each species were compatible
with the procreation and the rearing OF
progeny. Nevertheless in all those sexualy
reproducing organisms the primitive endow-
ment Of Immortality has been retained with
respect to their germ plasm. which has thus
been continuous through numberess genera
tons OF perishing organisms from tho first
origin OF sexual reproduction till the present
time. Now 1t is the union OF germ plasms
which is required to reproduce new individ-
uals OF multicellular organisms that deter
mines congenital variations on the part OF such
organisms. and thus furnishes natural selec-
ton with tho material for it's work in the way
OF organic evolution-work which is impossi-
BILE in the case OF unicellular organisms.
where variations never be con-
the direct action Of surrounding condi-
lions OF life. Again as the germ plasm
OF multicellular organisms is continuous from
generation to generation. and at each I'M
pregnation gives rise to a more or less novel
act OF congenital characters. natural selec-
ton. In picking out OF each generation the
congenital characters which are OF most ser-
vice to the organisms presenting them. is
really or fundamentally at work upon those
variations OF the germ plasm. which In turn
give origin to those variations of organisms
that are recognized as congenital. Therefore
natural selection has always to wait and to
watch for suoh variations OF germ plasm
as will eventually prove beneficial to
the individuals developed therefrom. who
will then transmit this peculiar quality
OF germ plasm to their progeny and
so on. Therefore also and this is most i'm
portant to remember-natural selection. as
thus working. becomes the one and only cause
Of organic evolution in all the multiceluiar
organisms. Just as the direct action Of the en-
vironment is the one and only cause Of it in
the case OF all the unlcellular organisms. But
inasmuch as the multicelluar organisms were
all in the first instance derived from the uni.
cellular. and inasmuch as their germ plasm |
Ia OF 80 stable nature that it can never be |
altered by any agencies internal. or external. |
to the organisms presenting 1t. the deduction |
follows that all congenital variations are |
the remote consequences of aboriginal differ |
ences on the part OF unicelluar ancestors. |
Lastly it follows also that these conRenital |
variations-al now SO entirely indie
pendent OF external conditions OF life and even
OF activities internal to organisms themselves
were originally and exclusively due to the
direct action Of such conditions on the liyes Of
their unicellular forefathers while even at the
present day no one congenital variation can
arise which is not ultimately due to differ
ences impressed upon the protopasmic sub
stance OF the germinal elem ents when the
parts OF which these are now composed con-
stituted integral parts OF protozoa which were
directly and differentaly affected by their re-
lations to their several environments.
Let us now look at the objections to Weiss
theory which Mr.. Romanes brings for
ward. Absolutely essential to the hypothesis
are the two distinctive postulates Of the per-
petual continuity Of germ plasm since the first
origin OF life. and Of its absolute stability since
the first origin Of sexual propagation. Mr.,
Romanes releRates TO sp appendix his exam
ination OF Weissmann's defence OF the former
postulate on grounds Of abstract reasoning.
while in hetextis considered only what Weiss
mann has advanced as evid ence posteriori.
Within this field Of evidence Weissmann has
developed three distinct lines OF verfcation,
viz. a. the migration Of germ cells in some
Of the Hydromeduse: tBl. the early separa-
ton OF germ cells In the ontogeny OF certain
and (CL the alleged invariability
Of organisms which are produced partheno-
yenetically. But Mr.. Romanes demonstrates
with respect to tAI that the eclalized charac-
.er OF germinal cells is fact which every
heory OF heredity must more or less recog-
,ize. and therefore. that the migration
If these cells, wherever It may be found
o occur. does not lend any peculiar
,ountenance to Weissmann's theory. There
nay be many reasons for such migration
,ther than the one which this theory assigns.
While the reason which 1t does assign Is rem
Tered improbable by the consideration that in
he Hydromeduse the material Of heredity Is
lready and richly difrused throughout the {