Vermont phÅ“nix. [volume] (Brattleboro, Vt.) 1834-1955, 1872-10-04
DIR Uy.IN'ES.u.

D.fEUI.fES.N.
The following report OF a recent lecture
by John Fiske will be of interest as ex-
planning the theory, now so widely adopted
among scientific men, known az Dar-
winism:
KNOWN FACTS OF ADAPTIVE ALTERATIONS
Mr.. Darwin in explaining the evolution
of higher from lower forms Of life, appeals
only To agencies which are still visibly in
action. Whether species in n state of ma
ture arc changing or not at the present
time, cannot be determined by direct obser-
vation, any more than the motion Of the
hour-hand Of clock could be detected by
gazing at ii for one second. But there are
innumerable cases in which species are
made TO change rapidly through the dolib-
crate Intervention of man. Notifications
in the specific characters of dOmesticated
organisms are the only ones which take
place so rapidly that we can actually OBJ
serve them and the agency which produ-
ces these notifications is selection, taking
advantage of that slight but universal va
ration in organisms implied by the fact
exactly alike. BY selectins and pairing
for many generations the finest specimens
of the different races of domestic animals,
man produces refined, perfected, and often
entirely unlike the original ones. Vegeta-
bic organisms are also operfected and chang
ed by artificial selection. Mr.. Darwins
great achievement has been TO show that
similar process Of selection going on
thro ghout the organic world without the
kno wldge or Intervention of man, tends
not only to maintain, but to produce adap-
tive alterations in plants and animals.
now THE INCREASE WAS KEPT WITHIN
BOUNDS.
The process is n simple one when once
we have the clue TO it, All plants and an
imais tend TO increase in high geometri-
cal ratio, and the old problem of the nails
in the horses shoe teaches us what an as
toun ding affair is geometrical rate of in
crease. 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 prob
able that the unchecked reproduction of
many insects, crustaceans and fishes could
not long go on without requiring the assim-
ilation of greater quantity Of matter than
is contained in the whole solar system.
We may now begin family to realize how
prodigous is the slaughter which unceas-
ingly goes on throughout the organic world.
Deadly battles have been incessantly wag-
ed on every square mile of the earth's life
bea ring surface, since life first began. 1t
is only thus that the enormous increase of
each species has been kept within bounds.
OF the many offspring produced by each
plant and animal, save in the case of those
highest in the scale, but few attain maturi-
ty and leave offspring behind them. In
this struggle for existence, a few favored
ones in each generation survive and propa-
gate in their offspring the qualities by vir-
tue of which they have survived; thus we
see what is meant by "natural selection"
The organisms which survive and proba-
gate their kind are those which are best
adapted to the conditions in which they
live; so that we may, by legitimate use
of metaphor, personify nature as n mighty
breeder, selecting from each generation
those individuals which are fieetest, strong
o,t, most sagacious, lions with supplest
muscles, wolves with keenest scent, flow
ers with sweetest noctar-untili in the course
of untold ages the numberless varieties of
or ganic life have been produced by the
50 me process of which man now takes adj
vantage, in order to produce variations to
suit his own caprices. Between natural
selection and selection by man, there is
4 Co
lection by man tends to produce varieties
adapted to satisfy human necessities or in
cination, and il has no direct reference to
the maintenance of the species. But nat
ural selection, working with the sternest of
methods, saves from the general slaughter
only those individuals which eau best take
care of themselves, and thus maintains
each species IN adoption to its environment.
CIRCUMSTANCES ALTER CASES.
If the conditions of the earth, the atmos-
phere, and the solar radience were every
where to remain forever unatered, and if
each race Of plant, and animals were al
ways to remain confined to one limited
area, all variations on either side Of the
wel-adjusted mean would be incessantly
cut OH Dy Hilurul SclecllOn, ana species
would be immutable. But constant chang
es have been going ON ever since our planet
first became fit TO support organic life no
part OF the earths surface is now or ever
has been, at rest the intensity of solar ra-
dance and the density of atmosphere are
ever altering, and every species of plant
and animal is continually pressing upon
the limits Of the area within which 1t is
confined. Such changes in the conditions
of life preclude the possibility OF organisms
remaining constant and living. A race OF
animals or plants in which no individuals
ever varied would sooner or later ineyita-
bly, be extermlnated, leaving no progeny.
Observation shows that there is no such
race. The members Of each species are ev-
er slightly varying, but so long as the en-
vironment remains constlnt natural selec-
tion prevents the variations from accumu-
lating ON either side of the mean which is
most advantageous to the species. When
Al.