ay from my home, but before I left I had the
satisfaction of seeing Phyllanthus sleeping. Some of the seeds which
you so kindly sent me would not germinate, or had not then germinated.
I received a letter yesterday from Dr. Breitenbach, and he tells me
that you lost many of your books in the desolating flood from which you
suffered. Forgive me, but why should you not order, through your brother
Hermann, books, etc., to the amount of 100 pounds, and I would send
a cheque to him as soon as I heard the exact amount? This would be no
inconvenience to me; on the contrary, it would be an honour and lasting
pleasure to me to have aided you in your invaluable scientific work to
this small and trifling extent. (690/3. See Letter 687, also "Life and
Letters," III., page 242.)

LETTER 691. TO F. MULLER.

(691/1. The following extract from a letter to F. Muller shows what was
the nature of Darwin's interest in the effect of carbonate of ammonia on
roots, etc. He was, we think, wrong in adhering to the belief that the
movements of aggregated masses are of an amoeboid nature. The masses
change shape, just as clouds do under the moulding action of the wind.
In the plant cell the moulding agent is the flowing protoplasm, but the
masses themselves are passive.)

September 10th, 1881.

Perhaps you may remember that I described in "Insectivorous Plants"
a really curious phenomenon, which I called the aggregation of the
protoplasm in the cells of the tentacles. None of the great German
botanists will admit that the moving masses are composed of protoplasm,
though it is astonishing to me that any one could watch the movement
and doubt its nature. But these doubts have led me to observe analogous
facts, and I hope to succeed in proving my case.

LETTER 692. TO F. MULLER. Down, November 13th, 1881.

I received a few days ago a small box (registered) containing dried
flower-heads with brown seeds somewhat sculptured on the sides. There
was no name, and I should be much obliged if some time you would tell me
what these seeds are. I have planted them.

I sent you some time ago my little book on earthworms, which, though
of no importance, has been largely read in England. I have little or
nothing to tell you about myself. I have for a couple of months been
observing the effects of carbonate of ammonia on chlorophyll and on the
roots of certain plants (692/1. Published under the title "The Action of
Carbonate of Ammonia on the Roots of