53.]) Hooker was convinced by my data, never as yet published in full,
only abstracted in the "Origin."

Page lxxviii.--I dispute whether a new race or species is necessarily,
or even generally, descended from a single or pair of parents. The
whole body of individuals, I believe, become altered together--like
our race-horses, and like all domestic breeds which are changed through
"unconscious selection" by man. (290/3. Bentham had said: "We must also
admit that every race has probably been the offspring of one parent or
pair of parents, and consequently originated in one spot." The Duke of
Argyll inverts the proposition.)

When such great lengths of time are considered as are necessary to
change a specific form, I greatly doubt whether more or less rapid
powers of multiplication have more than the most insignificant weight.
These powers, I think, are related to greater or less destruction in
early life.

Page lxxix.--I still think you rather underrate the importance of
isolation. I have come to think it very important from various grounds;
the anomalous and quasi-extinct forms on islands, etc., etc., etc.

With respect to areas with numerous "individually durable" forms, can it
be said that they generally present a "broken" surface with "impassable
barriers"? This, no doubt, is true in certain cases, as Teneriffe. But
does this hold with South-West Australia or the Cape? I much doubt.
I have been accustomed to look at the cause of so many forms as being
partly an arid or dry climate (as De Candolle insists) which indirectly
leads to diversified [?] conditions; and, secondly, to isolation from
the rest of the world during a very long period, so that other more
dominant forms have not entered, and there has been ample time for much
specification and adaptation of character.

Page lxxx.--I suppose you think that the Restiaceae, Proteaceae (290/4.
It is doubtful whether Bentham did think so. In his 1870 address he
says: "I cannot resist the opinion that all presumptive evidence is
against European Proteaceae, and that all direct evidence in their
favour has broken down upon cross-examination."), etc., etc., once
extended over the world, leaving fragments in the south.

You in several places speak of distribution of plants as if exclusively
governed by soil and climate. I know that you do not mean this, but I
regret whenever a chance is omitted of pointing out that the struggle
with other plants (and hostile animals)