2, Hesketh Terrace, Torquay [August 2nd, 1861].

I declare that you read the reviews on the "Origin" more carefully than I
do. I agree with all your remarks. The point of correlation struck me as
well put, and on varieties growing together; but I have already begun to
put things in train for information on this latter head, on which Bronn
also enlarges. With respect to sexuality, I have often speculated on it,
and have always concluded that we are too ignorant to speculate: no
physiologist can conjecture why the two elements go to form a new being,
and, more than that, why nature strives at uniting the two elements from
two individuals. What I am now working at in my orchids is an admirable
illustration of the law. I should certainly conclude that all sexuality
had descended from one prototype. Do you not underrate the degree of
lowness of organisation in which sexuality occurs--viz., in Hydra, and
still lower in some of the one-celled free confervae which "conjugate,"
which good judges (Thwaites) believe is the simplest form of true sexual
generation? (130/1. See Letter 97.) But the whole case is a mystery.

There is another point on which I have occasionally wished to say a few
words. I believe you think with Asa Gray that I have not allowed enough
for the stream of variation having been guided by a higher power. I have
had lately a good deal of correspondence on this head. Herschel, in his
"Physical Geography" (130/2. "Physical Geography of the Globe," by Sir
John F.W. Herschel, Edinburgh, 1861. On page 12 Herschel writes of the
revelations of Geology pointing to successive submersions and
reconstructions of the continents and fresh races of animals and plants.
He refers to a "great law of change" which has not operated either by a
gradually progressing variation of species, nor by a sudden and total
abolition of one race...The following footnote on page 12 of the "Physical
Geography" was added in January, 1861: "This was written previous to the