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fingers and five toes； quite perfect； the fourth was a girl； Marie； she
had five fingers and five toes； but her thumbs were deformed； showing a
tendency toward the sixth。
These children grew up； and when they came to adult years； they all
married； and of course it happened that they all married five…fingered
and five…toed persons。 Now let us see what were the results。 Salvator
had four children； they were two boys； a girl； and another boy； the
first two boys and the girl were six…fingered and six…toed like their
grandfather； the fourth boy had only five fingers and five toes。 George
had only four children； there were two girls with six fingers and six
toes； there was one girl with six fingers and five toes on the right
side； and five fingers and five toes on the left side； so that she was
half and half。 The last； a boy； had five fingers and five toes。 The
third； Andre； you will recollect； was perfectly well…formed； and he had
many children whose hands and feet were all regularly developed。 Marie；
the last； who； of course； married a man who had only five fingers； had
four children； the first； a boy； was born with six toes； but the other
three were normal。
Now observe what very extraordinary phenomena are presented here。 You
have an accidental variation arising from what you may call a
monstrosity； you have that monstrosity tendency or variation diluted in
the first instance by an admixture with a female of normal construction；
and you would naturally expect that； in the results of such an union；
the monstrosity； if repeated； would be in equal proportion with the
normal type； that is to say； that the children would be half and half；
some taking the peculiarity of the father； and the others being of the
purely normal type of the mother； but you see we have a great
preponderance of the abnormal type。 Well； this comes to be mixed once
more with the pure； the normal type； and the abnormal is again produced
in large proportion； notwithstanding the second dilution。 Now what
would have happened if these abnormal types had intermarried with each
other； that is to say； suppose the two boys of Salvator had taken it
into their heads to marry their first cousins； the two first girls of
George； their uncle？ You will remember that these are all of the
abnormal type of their grandfather。 The result would probably have
been； that their offspring would have been in every case a further
development of that abnormal type。 You see it is only in the fourth；
in the person of Marie； that the tendency； when it appears but slightly
in the second generation； is washed out in the third； while the progeny
of Andre； who escaped in the first instance； escape altogether。
We have in this case a good example of nature's tendency to the
perpetuation of a variation。 Here it is certainly a variation which
carried with it no use or benefit； and yet you see the tendency to
perpetuation may be so strong； that； notwithstanding a great admixture
of pure blood； the variety continues itself up to the third generation；
which is largely marked with it。 In this case； as I have said； there
was no means of the second generation intermarrying with any but
five…fingered persons； and the question naturally suggests itself； What
would have been the result of such marriage？ Reaumur narrates this
case only as far as the third generation。 Certainly it would have been
an exceedingly curious thing if we could have traced this matter any
further； had the cousins intermarried； a six…fingered variety of the
human race might have been set up。
To show you that this supposition is by no means an unreasonable one；
let me now point out what took place in the case of Seth Wright's
sheep； where it happened to be a matter of moment to him to obtain a
breed or raise a flock of sheep like that accidental variety that I
have describedand I will tell you why。 In that part of Massachusetts
where Seth Wright was living； the fields were separated by fences； and
the sheep； which were very active and robust； would roam abroad； and
without much difficulty jump over these fences into other people's
farms。 As a matter of course； this exuberant activity on the part of
the sheep constantly gave rise to all sorts of quarrels； bickerings；
and contentions among the farmers of the neighbourhood； so it occurred
to Seth Wright； who was； like his successors； more or less 'cute； that
if he could get a stock of sheep like those with the bandy legs； they
would not be able to jump over the fences so readily； and he acted upon
that idea。 He killed his old ram； and as soon as the young one arrived
at maturity； he bred altogether from it。 The result was even more
striking than in the human experiment which I mentioned just now。
Colonel Humphreys testifies that it always happened that the offspring
were either pure Ancons or pure ordinary sheep； that in no case was
there any mixing of the Ancons with the others。 In consequence of
this； in the course of a very few years； the farmer was able to get a
very considerable flock of this variety； and a large number of them
were spread throughout Massachusetts。 Most unfortunately； howeverI
suppose it was because they were so commonnobody took enough notice
of them to preserve their skeletons； and although Colonel Humphreys
states that he sent a skeleton to the President of the Royal Society at
the same time that he forwarded his paper； I am afraid that the variety
has entirely disappeared； for a short time after these sheep had become
prevalent in that district； the Merino sheep were introduced； and as
their wool was much more valuable； and as they were a quiet race of
sheep； and showed no tendency to trespass or jump over fences； the
Otter breed of sheep； the wool of which was inferior to that of the
Merino； was gradually allowed to die out。
You see that these facts illustrate perfectly well what may be done if
you take care to breed from stocks that are similar to each other。
After having got a variation； if； by crossing a variation with the
original stock； you multiply that variation； and then take care to keep
that variation distinct from the original stock； and make them breed
together；then you may almost certainly produce a race whose tendency
to continue the variation is exceedingly strong。
This is what is called 〃selection〃； and it is by exactly the same
process as that by which Seth Wright bred his Ancon sheep； that our
breeds of cattle； dogs； and fowls； are obtained。 There are some
possibilities of exception； but still； speaking broadly； I may say that
this is the way in which all our varied races of domestic animals have
arisen； and you must understand that it is not one peculiarity or one
characteristic alone in which animals may vary。 There is not a single
peculiarity or characteristic of any kind； bodily or mental； in which
offspring may not vary to a certain extent from the parent and other
animals。
Among ourselves this is well known。 The simplest physical peculiarity
is mostly reproduced。 I know a case of a man whose wife has the lobe of
one of her ears a little flattened。 An ordinary observer might
scarcely notice it； and yet ever