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"THE ORIGIN OF SPECIES" IN ITS
RELATION TO DARWIN'S SUB
SEQUENT WORK.
PART TWO.
Having finished the Cirripede book ,
Darwin wrote to Sir John Hooker in
September , 1854 , "I shall now in a
day or two look over my old notes on
species ; " and this remark may well
bring us to the subject for which all
the foregoing lias been an introduction
the subject of species. As far back
as July , 1837 , he opened his first note
book for facts in relation to the origin
of species , about which ho says ho
had long reflected , and at which lie
never ceased to work for the next
twenty years. A letter written to
Lyell , in 1838 , is interesting , as it
gives the first clear indication of how
he was beginning to think deeply upon
the subject of species. "Ihave lately
been tempted to be idle i. e. , as far as
pure geology is concerned by the de
lightful number of new views which
have been coming in thickly and stead
ily , on the classification and affinities
and instincts of animals , bearing on
the question of species. Note-book
after note-book lias been filled with
facts which begin to group themselves
clearly under sub-laws. " And again ,
in a letter to his cousin Fox about
the same time , "I am delighted to
hear you have not forgotten my ques
tion about the crossing of animals. It
is my prime hobby , and I really think
some day I shall bo able to do some
thing in that most intricate subject ,
species and varieties. ' '
Up to the publication of "The
Origin of Species" in 1859 , it was one
of the canons of orthodox natural his
tory that species were absolutely fixed
and unchangeable , that the transmu
tation of species never occurred
species were immutable. This meant
that there were certain forms of ani
mals and plants having well defined
characters which never changed. All
the forms having these characters
were grouped together as a spe
cies , and were believed to have
come down through innumerable ages
without change. Species , again , were
composed of smaller groups , called
varieties , which , however , were not
considered immutable ; the name
' ' variety , ' 'of course , indicates change.
Within the limits of the specific char
acteristics , these varieties were sup
posed to be capable of undergoing
modification. But one point was al
ways tenaciously maintained , viz : that
as the modification could never extend
so far as to change one species into
another , that modification could never
affect specific characters. If one or
two forms previously ranked as be
longing to the same species exhibited
marked deviation from the specific
limits , it was at once ranked as a
different species. If , on the other
hand , two forms previously placed in
different species were found to ex
hibit close relationship , they were im
mediately placed in the same species.
This argument made it possible to
avoid all stumbling tblocks to a belief
"
in the immutability "of species , and its
incessant use blinded some very acute
minds to the fact that they were wor
shipping a shadow and not a reality.
To us it may appear amazing that
the absurdity of the argument in a cir
cle concerning the immutability of
species had not been exposed long before -
fore Darwin's time ; but I venture to
point out that fixed ideas new or old
always take a great deal of killing.
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It. must not bo forgotten , of course ,
that fifty years before this time
Lamarck in his " Philosophic Zoolog-
ique , " had stoutly denied , and had
reasoned against , the immutability of
species. "Tho term species , " he
writes , "is applied to every collection
of similar individuals produced by
other individuals like themselves. To
this definition is added the supposition
that individuals composing a species
never vary in their specific characters ,
and consequently a species has an ab
solute constancy in nature. It is this
supposition I propose to combat , be
cause evident proofs obtained by ob
servation show that it is unfounded. ' '
He then goes on to point out ' ' the
difficulty and often embarrassment of
deciding whether a given form should
be ranked as a species or a variety ( the
very term of which indicates mutabil
ity ? ) . In fact , the wider our kno\yl-
edge of the different organized bodies
the more embarrassing does it be
come to decide what ought to be re
garded as species. In proportion as
we accumulate the productions of
nature , in proportion as our collec
tions are enriched , so do we see almost
every gap filled up and our lines of
separation effaced. In fact the larger
our collections become , the more evi
dent is it that everything passes by
insensible graduations into something
else , and that striking differences van
ish , leaving only minute , even purile
distinctions. Animals form a
branched series irregularly graded
which has no discontinuity in its
parts. In short , the more extended
our knowledge of different forms , the
less striking the differences , the less
obvious the species. ' '
Lamarck , in 1809 , and Darwin , in
1858 , botli came to the conclusion , op
posed to the opinion of their time ,
that species were not immutable. Hav
ing done so , they were both faced with
the same quesiton , viz : How have
species originated ? What has been
the origin of species ? It is in the nat
ure of their answer to this question
that the difference in value of the
work of the two men in solving the
problem of evolution lies. If we re
member that Lamarck died in 1829 ,
we shall not be likely to underestimate -
mate his labors.
Lamarck attributed the changes
necessary for the transmutation of
species to two special influences , viz :
1. The environment , i. o. , the total
ity of surrounding external circum
stances. 2. To the effects of the
transmission of the use and dis-nse of
parts. The changes produced by the
environment and the use and dis-use of
parts being inherited , might become
gradually intensified until a new
species might be formed. These in
fluences are now known as the La-
marckiau factors of evolution , and it
is at present the fashion in this coun
try to largely magnify their supposed
importance. Darwin , while by no
means ignoring the influences of en
vironment , attributed the chief power
in modifying species to that factor in
evolution which is intimately associ
ated with his name , viz : To the
process of natural selection , and in a
lesser degree to sexual selection.
These are appropriately called the
Darwinian factors in evolution. The
great value of Darwin's work consist
ed , not only of his hypotheses , but of
the remarkable array of facts and of
experiments which it included. So
simple is Darwin's theory of natural
selection and so conspicuously is its
verity proved , that any young lady of
nineteen summers can easily under
stand what it is if she will read a little
and will think a little more.
I hope that what I have written may ,
to some extent , enable the reader to
realize the importance of this ques
tion of species , and to understand why
so much attention lias been directed
to these small groups of animals and
plants. It is obvious that before the
question of the origin of species was
admitted , the question of the origin
of the larger groups of orders , classes ,
etc. , was not one for consideration ,
as obviously the less cannot include
the greater. Therefore , apart from
mere speculation and I do not hesitate
to condemn idle speculation as akin
to what is called "building castles in
the air" apart from more guessing ,
there could be no definite knowledge
regarding the true relations of the an
imal kingdom as a whole. When
once the question of species had been
even partially explained , the key to
the whole subject was at hand.
This accounts for the immense inter
est excited in the scientific world
when Darwin and Wallace , absolutely
independently , but at the same time ,
discovered the process of natural selec
tion. When "The Origin of Species"
was published in 1859 , the curiosity of
a much wider opinion as revolution-
ized. In the "Origin of Species" Darwin -
win suggested a cause which , while
acting very slowly , yet acting with
certainty , would , by extremely slow
degrees , be easily able , provided there
was sufficient time , to produce changes
great enough to account for specific
differences. That cause Darwin named
Natural Selection.
I have already referred to the direct
personal influence of Sir Charles Lyell
on Darwin's scientific development. I
may here point out that LyelPs work
as a geologist was decidedly prepara
tive , though unconsciously so , to Dar
win's teaching. By showing and em
phasizing the fact that geological
changes , even those which appear to
us of stupendous magnitude had been
brought about gradually by slowly
acting causes , he prepared the way
for similar views regarding changes
in animals and plants in other words ,
he proved that the great differences
between the various animals and be
tween the innumerable plants had been
produced by a great many small
changes. in.
It is an interesting fact that both
Darwin and Wallace were led to the
idea of natural selection by a perusal
of Malthus' remarkable Essay on
Population , first published in 1798.
The argument of Malthus was quite
simple. The population , he said , in
creases in geometric ratio , the supply
of food in arithmetic ratio only ; hence
a struggle must arise and the chief
check acting directly or indirect
ly on the growth of popula
tion is deficiency of food. Malthus'
hypothesis applied only to human be
ings. Darwin's theory of natural
selection is applicable to the whole
animal and vegetable world. Any
body can understand that a struggle is
going on that a perpetual battle for
existence is always in progress. Many
more animals for example , are born
than can possibly be supported , and
they therefore fight for food , consequently
quently for life. Those which have
any kind of advantage over the rest
will have the better opportunity of
surviving. Or , to put the fact in an
other way , a vast number of forms of
animals and vegetable life are propa
gated which , we know for certain ,