The Charleston daily news. [volume] (Charleston, S.C.) 1865-1873, 1872-06-01
THE DARWINIAN THEORY.
THE CAUSES OF ORGANIC EVOLUTION

THE CAUSES OF ORGANIC EVOLUTION
Darwin Defended - Nature Gren
Stock-Breeder-TheA Antiquity of Nor
The Relatio nshfp of Apes to Mem
Civilization the Chief Tendency o
Mans Development.
A very interesting lecture on Darwlnisn
was delivered recently by Professor Johr
Fiske, in New York City. In speaking of The
origin and progress of Mr.. Darwln's investIga
tioDs, he noted with admiration the earnest
ness and patience which enabled that eminen
savapt to labor for twenty-five years upon hi'
theories without publication. We give some
extracts from the lecture as we find 1t reported
in the New York Tribune:
KNOWN FACTS OF ADAPTIVE ALTERATIONS.
Mr.. Darwin. In explaining the evolution o.
higher from lower forms Of llfe,. appeals only
to agencies which are still visby In action
Whether species in state 0fnature are chang
ing or not At the present time, cannot be deter
mined by direct obsprVatlon,a any more than the
motion of the hour-hand of clock could be
detected by gazing at 1t for one second. Bul
there are innumerabe cases In which species
are made TO change rapidly through the de-
llberale Intervention Of IMAM. Notifications
in the specific characters OF domesticcted or
ganisms are The ouly ones which take place
so rapidly that we actually observe them; and
| the agency which produces these modthca
lions ls selection, taking advantage of this
slight but universal variation 10 organisms
| implied by the lacl that no two individuals ID
any SPECIES are exactly alike. By selecting
| ri tnr finest
specimens Ol The different races of domestic
| animals, man produces breeds refined, per
| fected, and often entirely unlike the Original
Ones Vegetable organisms ore also perlrCl-
| ed and changed by artificial selection. Mr.
Darwin's great achievement mas oeen 70 snow
| thai similar process uf selection going on
throughout the organic world without the
knowledge or Intervention Of man, lends not
only to maintain, but 10 produce adaptive ul-
| terations in plants and animals.
HOW THE INCREASE WAS KEPT WITHIN BOUNDS.
The process Is simple one when once We
have the clue 10 1t. ALI plants aud animals
| tend 10 increase In high geonetrcal ralio,
| and the Old problem of The nails In the
norse's shoe teaches us what an astounding
affair Is geometricaI rate of Increase. A
| plant yielding one hundred seeds yearly
would In twenty years. if all the seeds were
| to reach maturity, produce ten duodecillions
of adult plants 1t Is probable that the I'm.
checked reproduction OF many insects, cru5-
tace&ns and fishes. could not long 60 on
without requiring the assimilation OF greater
| quantity OF matter than ls contained IN the
family to realize how prodiGons Is the
| slaughter which INCREASINGLY goes on through
out The orgaaic world. Deadly battles have
been incpssantly waged on every square mile
of the earth's lie-btaring surface since life
first began. 1t Is only thus that the enormous
increase oil each species has been keEt within
| bounds. OF the many offspring produced by
those In the highest scale, but few attain matll-
rily and leave offspring behind them.
In this struggle for existence, few
favored ones in each generation survive
and propagate In their offspring the
qualities by virtue If which they have sur
vlved. Thus we see what is meant by "natn-
raj selection The organisms which survive
best adapted TO the conditions In which they
live; so that we may, by legitimate use OF
melapaUr, personliy nature as mighty
brpeder, selecting from each generation those
individuals " hich are leelest, strongest, most
sagacions, lions with suDD'esL muscles, wolves
with keeneIt scent, flowers with sweetest
nectlr--lintll in tho ooureo OF untold ages
The numberless varitles of organic life have
been produced By the eame process Of which
man now takes advantage, iu order to pro-
duce variations TO suit his own caprlces Be.
tween natural selection and selection by man,
there Is, however, one important difference.
Selection by man tends 10 produce varieties
adapted to satisfy human necessities or incl-
nalion, and It has no direct reference to the
maintenance cf the species. But natural
selection, working with the sternesJ OF meth
ods, saves from Lne general slaughter only
those individuals which can best l"ke care OF
themselves, and thus maintains each species
in adaptation to Its environment.
CIRCUMSTANCES ALTER CASES.
If the conditions of the earth, the atmos
phere, and the solar radiance were every
where 10 remain forever unalterrd, aud II
each race OF Dlanls and animals were always
TO remain contned 10 one limited area, all
variations on either side of the wel-adjustpd
mean would be necessarily cut off BY natural
SELECTION, and species would be immutabe.
But constant changes have been going on
ever since our planet first became ft to sup
port organic life; no part OF the earths sur
lace ts now, or ever has been, at rest; the in-
tensity of solar radiance and the density of at
mosphere are ever altering, and every species
of plant and animal Is continually pressing
upon the llmifs of the area within which lis Is
confined. Such changes In The conditions OF
life preclude he possibility Of organisms re-
naming constant and living. A race OF anil.
mals or plants In which no individuals ever
terminated, leaving no progeny. Ooserva-
tlon shows that there is no such race. The
members OF each species are ever slightly
varying, but so long as the environment re-
mains constant, Natural selection prevents
the variations from accommodating on
either side OF the mean which ls most
advantageous to the species. When the
environment changes, If certain variations
on one side of the established mean tend 10
bring the individuals which manifest them
into closer adaptation to the new environ
ment, these individuals will survive In The
struggle for liz, and thus The average charac-
ter Of the species will be slightly altered. Tne
amount of variation, thus preserved aud en-
hanced, must In the course Of long ages be-
come enormous. But these changes directly
caused by natural selection are greatly aided
and emphasized by other changes Indirectly
produced by what Is called The law of use and
dsuse, and by correlation of growth, or inter-
nal equilibralion-she effect produced upon
| any part of the organism by change in re-
| lated or neighborlng part. The disuse OF any
| ply sical power or any member. und the
| changes In all parts Of an animals frame
| whcn would be brought about by change in
one part caused by natural selection, cannot
| fall 10 modiiy the eniire structure, temppra-
ment and mode of life. Even such slight
| change as an increased thickness oil the woUily
coat Of mammals may, by altering the eXcre-
tory power Of the skin, affect the functions OF
| the lungs, liver and kidneys, and thus in
directly increase OF diminish the size of the
animal, which, In turn, will mo1ify Its speed,
/ its muscular development, lts mental iuCul-
| tips and itr habits of life