Certain Plants and on Chlorophyll
Bodies," "Linn. Soc. Journ." XIX., 1882, pages 239-61, 262-84.), but the
subject is too difficult for me, and I cannot understand the meaning of
some strange facts which I have observed. The mere recording new facts
is but dull work.

Professor Wiesner has published a book (692/2. See Letter 763.), giving
a different explanation to almost every fact which I have given in my
"Power of Movement in Plants." I am glad to say that he admits that
almost all my statements are true. I am convinced that many of his
interpretations of the facts are wrong, and I am glad to hear that
Professor Pfeffer is of the same opinion; but I believe that he is
right and I wrong on some points. I have not the courage to retry all my
experiments, but I hope to get my son Francis to try some fresh ones to
test Wiesner's explanations. But I do not know why I have troubled you
with all this.

LETTER 693. TO F. MULLER. [4, Bryanston Street], December 19th, 1881.

I hope that you may find time to go on with your experiments on such
plants as Lagerstroemia, mentioned in your letter of October 29th, for
I believe you will arrive at new and curious results, more especially if
you can raise two sets of seedlings from the two kinds of pollen.

Many thanks for the facts about the effect of rain and mud in relation
to the waxy secretion. I have observed many instances of the lower side
being protected better than the upper side, in the case, as I believe,
of bushes and trees, so that the advantage in low-growing plants is
probably only an incidental one. (693/1. The meaning is here obscure: it
appears to us that the significance of bloom on the lower surface of the
leaves of both trees and herbs depends on the frequency with which all
or a majority of the stomata are on the lower surface--where they are
better protected from wet (even without the help of bloom) than on the
exposed upper surface. On the correlation between bloom and stomata, see
Francis Darwin "Linn. Soc. Journ." XXII., page 99.) As I am writing away
from my home, I have been unwilling to try more than one leaf of the
Passiflora, and this came out of the water quite dry on the lower
surface and quite wet on the upper. I have not yet begun to put my notes
together on this subject, and do not at all know whether I shall be able
to make much of it. The oddest little fact which I have observed is that
with Trifolium resupinatum, one half of the leaf (I th