nha, _volcanic_ islands covered with craters
we know lately did not support any organisms. How unlike these
islands in nature to neighbouring lands. These facts perhaps more
striking than almost any others. [Geology apt to affect geography
therefore we ought to expect to find the above.]
Geological-geographical distribution. In looking to past times we
find Australia equally distinct. S. America was distinct, though
with more forms in common. N. America its nearest neighbour more in
common,--in some respects more, in some less allied to Europe.
Europe we find <?> equally European. For Europe is now part of Asia
though not <illegible>. Africa unknown,--examples, Elephant,
Rhinoceros, Hippopotamus, Hyaena. As geology destroys geography we
cannot be surprised in going far back we find Marsupials and
Edentata in Europe: but geology destroys geography.

Now according to analogy of domesticated animals let us see what would
result. Let us take case of farmer on Pampas, where everything
approaches nearer to state of nature. He works on organisms having
strong tendency to vary: and he knows <that the> only way to make a
distinct breed is to select and separate. It would be useless to
separate the best bulls and pair with best cows if their offspring run
loose and bred with the other herds, and tendency to reversion not
counteracted; he would endeavour therefore to get his cows on islands
and then commence his work of selection. If several farmers in different
_rincons_{128} were to set to work, especially if with different
objects, several breeds would soon be produced. So would it be with
horticulturist and so history of every plant shows; the number of
varieties{129} increase in proportion to care bestowed on their
selection and, with crossing plants, separation. Now, according to this
analogy, change of external conditions, and isolation either by chance
landing <of> a form on an island, or subsidence dividing a continent, or
great chain of mountains, and the number of individuals not being
numerous will best favour variation and selection{130}. No doubt change
could be effected in same country without any barrier by long continued
selection on one species: even in case of a plant not capable of
crossing would easier get possession and solely occupy an island{131}.
Now we can at once see that <if> two parts of a continent isolated, new
species thus generated in