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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 every one of her children has an
approximation to the same peculiarity to some extent。 If you look at
the other extreme； too； the gravest diseases； such as gout； scrofula；
and consumption； may be handed down with just the same certainty and
persistence as we noticed in the perpetuation of the bandy legs of the
Ancon sheep。
However； these facts are best illustrated in animals； and the extent of
the variation； as is well known； is very remarkable in dogs。 For
example； there are some dogs very much smaller than others； indeed； the
variation is so enormous that probably the smallest dog would be about
the size of the head of the largest； there are very great variations in
the structural forms not only of the skeleton but also in the shape of
the skull； and in the proportions of the face and the disposition of
the teeth。
The Pointer； the Retriever； Bulldog； and the Terrier； differ very
greatly； and yet there is every reason to believe that every one of
these races has arisen from the same source；that all the most
important races have arisen by this selective breeding from accidental
variation。
A still more striking case of what may be done by selective breeding；
and it is a better case； because there is no chance of that partial
infusion of error to which I alluded； has been studied very carefully
by Mr。 Darwin；the case of the domestic pigeons。 I dare say there may
be some among you who may be pigeon 'fanciers'； and I wish you to
understand that in approaching the subject； I would speak with all
humility and hesitation； as I regret to say that I am not a pigeon
fancier。 I know it is a great art and mystery； and a thing upon which a
man must not speak lightly； but I shall endeavour； as far as my
understanding goes； to give you a summary of the published and
unpublished information which I have gained from Mr。 Darwin。
Among the enormous variety；I believe there are somewhere about a
hundred and fifty kinds of pigeons；there are four kinds which may be
selected as representing the extremest divergences of one kind from
another。 Their names are the Carrier； the Pouter； the Fantail； and the
Tumbler。 In the large diagrams they are each represented in their
relative sizes to each other。 This first one is the Carrier； you will
notice this large excrescence on its beak； it has a comparatively small
head； there is a bare space round the eyes； it has a long neck； a very
long beak； very strong legs； large feet； long wings； and so on。 The
second one is the Pouter； a very large bird； with very long legs and
beak。 It is called the Pouter because it is in the habit of causing
its gullet to swell up by inflating it with air。 I should tell you that
all pigeons have a tendency to do this at times； but in the Pouter it
is carried to an enormous extent。 The birds appear to be quite proud
of their power of swelling and puffing themselves out in this way； and
I think it is about as droll a sight as you can well see to look at a
cage full of these pigeons puffing and blowing themselves out in this
ridiculous manner。
The third kind I mentionedthe Fantailis a small bird； with
exceedingly small legs and a very small beak。 It is most curiously
distinguished by the size and extent of its tail； which； instead of
containing twelve feathers； may have many more；say thirty； or even
moreI believe there are some with as many as forty…two。 This bird
has a curious habit of spreading out the feathers of its tail in such a
way that they reach forward； and touch its head； and if this can be
accomplished； I believe it is looked upon as a point of great beauty。
But here is the last great variety；the Tumbler； and of that great
variety； one of the principal kinds； and one most prized； is the
specimen represented herethe short…faced Tumbler。 Its beak is
reduced to a mere nothing。 Just compare the beak of this one and that
of the first one； the CarrierI believe the orthodox comparison of the
head and beak of a thoroughly well…bred Tumbler is to stick an oat into
a cherry； and that will give you the proper relative proportions of the
head and beak。 The feet and legs are exceedingly small； and the bird
appears to be quite a dwarf when placed side by side with this great
Carrier。
These are differences enough in regard to their external appearance； but
these differences are by no means the whole or even the most important
of the differences which obtain between these birds。 There is hardly a
single point of their structure which has not become more or less
altered； and to give you an idea of how extensive these alterations are；
I have here some very good skeletons； for which I am indebted to my
friend； Mr。 Tegetmeier； a great authority in these matters； by means of
which； if you examine them by…and…by； you will be able to see the
enormous difference in their bony structures。
I had the privilege； some time ago； of access to some important MSS。 of
Mr。 Darwin； who； I may tell you； has taken very great pains and spent
much valuable time and attention on the investigation of these
variations； and getting together all the facts that bear upon them。 I
obtained from these MSS。 the following summary of the differences
between the domestic breeds of pigeons； that is to say； a notification
of the various points in which their organization differs。 In the
first place； the back of the skull may differ a good deal； and the
development of the bones of the face may vary a great deal； the back
varies a good deal； the shape of the lower jaw varies； the tongue
varies very greatly； not only in correlation to the length and size of
the beak； but it seems also to have a kind of independent variation of
its own。 Then the amount of naked skin round the eyes； and at the base
of the beak； may vary enormously； so may the length of the eyelids； the
shape of the nostrils； and the length of the neck。 I have already
noticed the habit of blowing out the gullet； so remarkable in the
Pouter； and comparatively so in the others。 There are great
differences； too； in the size of the female and the male； the shape of
the body； the number and width of the processes of the ribs； the
development of the ribs； and the size； shape； and development of the
breastbone。 We may notice； too；and I mention the fact because it has
been disputed by what is assumed to be high authority；the variation
in the number of the sacral vertebrae。 The number of these varies from
eleven to fourteen； and that without any diminution in the number of
the vertebrae of the back or of the tail。 Then the number and position
of the tail…feathers may vary enormously； and so may the number of the
primary and secondary feathers of the wings。 Again； the length of the
feet and of the beak；although they have no relation to each other；
yet appear to go together；that is； you have a long beak wherever you
have long feet。 There are differences also in the periods of the
acquirement of the perfect plumage；the size and shape of the
eggs；the nature of flight； and the powers of flight；so…called
〃homing〃 birds having enormous flying powers；* while； on the other
hand； the little Tumbler is so called because of its extraordinary
faculty of turning head over heels in the air； instead of pursuing a
direct course。 And； lastly； the dispositions and voices of the birds
may vary。 Thus the case of the pigeons shows you that there is hardly
a single particular；whether of instinct； or habit； or bony structure；
or of plumage；of either the internal economy or the external shape；
in which some variation or change may not take place； which； by
selective breeding； may become perpetuated； and form the foundation of；
and give rise to； a new race。
＇footnote： The 〃Carrier；〃 I learn from Mr。 Tegetmeier； does
not 'carry'； a high…bred bird of this breed being but a
poor flier。 The birds which fly long distances； and come
home；〃homing〃 birds；and are consequently used as
carriers； are not 〃carriers〃 in the fancy sense。＇
If you carry in your mind's eye these four varieties of pigeons； you
will bear with you as good a notion as you can have； perhaps； of the
enormous