ot know to what
fact "pig in India" refers.

Now in crossing it is certain every peculiarity in form and constitution
is transmitted: an alpine plant transmits its alpine tendency to its
offspring, an American plant its American-bog constitution, and <with>
animals, those peculiarities, on which{77} when placed out of their
natural conditions they are incapable of breeding; and moreover they
transmit every part of their constitution, their respiration, their
pulse, their instinct, which are all suddenly modified, can it be
wondered at that they are incapable of breeding? I think it may be truly
said it would be more wonderful if they did. But it may be asked why
have not the recognised varieties, supposed to have been produced
through the means of man, [not refused to breed] have all bred{78}.
Variation depends on change of condition and selection{79}, as far as
man's systematic or unsystematic selection <has> gone; he takes external
form, has little power from ignorance over internal invisible
constitutional differences. Races which have long been domesticated, and
have much varied, are precisely those which were capable of bearing
great changes, whose constitutions were adapted to a diversity of
climates. Nature changes slowly and by degrees. According to many
authors probably breeds of dogs are another case of modified species
freely crossing. There is no variety which <illegible> has been <illegible>
adapted to peculiar soil or situation for a thousand years and another
rigorously adapted to another, till such can be produced, the question
is not tried{80}. Man in past ages, could transport into different
climates, animals and plants which would freely propagate in such new
climates. Nature could effect, with selection, such changes slowly, so
that precisely those animals which are adapted to submit to great
changes have given rise to diverse races,--and indeed great doubt on
this head{81}.

{77} This sentence should run "on which depends their incapacity to
breed in unnatural conditions."

{78} This sentence ends in confusion: it should clearly close with
the words "refused to breed" in place of the bracket and the
present concluding phrase.

{79} The author doubtless refers to the change produced by the
_summation_ of variation by means of selection.

{80} The meaning of this sentence is made clear by a passage in the
MS. of 1844:--"Until man selects two vari