The sun., 1900-12-23

" v =
NJ mind ~ oven adyonned IHu... u.,
time Darwin vns preparing m. I..' u.l
remembering how srnBIi Wps OH" u..t
which had been produced hy lu0nr Du,..
tnmnrck the author uf N'stig,s OFF Goa.
,lon and ~. .nrlirr wrilrss ~ Il.r...
gpcnccr. that W. can adequately r..
tho narvcllou. work that hr n,,uWr ..'.'
l.. ~ now briefly consider ne ,s4,r..
nature ~ this nov theory. which On ~ '.v
bfinf yotr- bocnmc tho established hoNr' .!
the great majority of the stuicnts ~ nature,
and which also gave new Interest IN nli.r,
10 tho whole thinking world
The theory ~ natural selection Il found,
upon a few groups of thoroughly aar,r.
,ained and universally admitted fa",.
with the direct and necessary rDulls =
those facts.
Tho first group ~ facts consists ~ ~,
grea powers Of increase Of all orPauisu,
and the circumstance that. notwith-lauI-
ing this great yearly Increase the nctul
population ~ each species remains s'd-
tionarv. there being no permanent incroas.
Now thCsc two facts were recognized Nv
Button, but though, Of course. known .
all subsequent writer's, were fully npprcoi1-
atcd or thought out To their logical rcs'ils
by none OF thcm. lamarcs. 80 far "a
can ascertain, took no notice Of them what
ever. Darwin has given illustrations =
these facts In Chapter ". of the OriHa
Of Species. and have added others IN tho
second chapter OF my parwinism." That
the population of each species rem1n,
stationary, with. of course. considerable
fluctuations. Ia both "A matter Of Observation
and Of reasoning. The powers of incr'l.,
OF all creatures are 50 great that If therc j,
In any country room and food for larger
number OF any species they will ba pro-
duced in year or two. II Is Impossible.
therefore. to believe that, In state Of natur,
where all kinds OF animals and plants have
lived together as best they could for thou
sands of years, there can be any important
difference in their numbers from year 10
year or from century to century.
Now II Is as consequence Of these two
indispuable facts that the struggle for
existence necessarily results. For II every
year each pair of animals or each plan.
produces only ten young animals or plants,
and this Is very far below the average, and
II the adult life Of these Is taken at ten
years. again below the average Of the
higher plants and animals. then unless
some Of tho parents die the whole Of the
offspring must die of every year: or, IN
other words. only as many young can sur
vive as are necessary to replace the old ones
that die. Hence the deaths must always
ION the average and in the long rum equal
the births. This terrible yearly destruction
Is an absolutely certain fact. as well as an
Inevitable result Of the two preceding facts.
and II is said to be due TO the struggle
for existence. This struggle is manifold
In It's nature. individuals Of the sans
species struggle together for food. for light.
for moisture they struggle also agains.
other species having the same wants they
struggle against every kind OF enemy,
from parasitic worms and insects up 10
carnivorous animals; and there is a con.
tinua struggle with the forces Of nature
frosts, rains, droughts. floods and tompests.
These varied causes OF destruction NAV
be seen constantly at work by any one who
looks for them. They act from the mo.
ment OF birth. being more especially de-
structive to the young: and as only one in
ten or fifty or thousand according TO
the rate OF increase Of the particular species,
can possibly come to the full breeding
age, We feel compelled to ask ourselves
What determines the nine or the forty-nina
or the nine hundred and nlncty-nine. "A,
the case may be, which die and the one
which survives? Darwin calls this process
Of extermination one Of " natural selection
that is, by this process nature weeds ont
4 ba IN ha Iar r,ta
the imperfect in any way. OF course
what may be called chance or accident
produces many deaths Of individuals other
wise well fitted 10 live. but if we think of
the process going on day by day and year
by year till only one in a hundred OF thos,
born In given area Is left alive. II IS I'm
possible to suppose that the one which has
passed through all the dangers and risks
which have been fatal to. say. his ninety
nine relations. was not, in oil tho faculties
and qualities essential TO the continuancs
OF the race, decidedly better organized
than the bulk Of those which suocumbed.
Herbert Spencer calls the process the : sur
vival Of the fttest.- and though the term
may not be strictly accurate In the case
Of any one species In any one year. yet
when we consider that the struggle Ia going
on every year. during the whole duration
OF each species. we cannot doubt that.
on the whole. and In the long run, those
which survive are among the fttest. The
struggle Is so severe. so incessant. that the
smallest defect In any sense organ, any
physical weakness. any imperfection IN
will almost certainly at one
time or another, be fatal
This continual wedding out Of the less
Al. In every generation. and with excep-
tional severity in recurring adverse seasons.
will produce two distinct effects. which
require to be clearly distinguished. The
lrst is the preservation of each species
N the highest state OF adaptation to the
conditions OF its existence: and. therefore,
so long as those conditions remain un.
changed the effect Of natural selection
$ TO keep each woll-adaptcd species also
The second effect Is pro.
iuoed whenever the conditions vary. when,
.