ving leaves a very little weak hydrochloric acid, I can
make them digest albumen--i.e. white of egg--quicker than they can do
naturally. I most heartily thank you for all your kindness. I have been
pretty bad lately, and must work very little.

LETTER 717. TO J. BURDON SANDERSON. September 13th [1873].

How very kind it was of you to telegraph to me. I am quite delighted
that you have got a decided result. Is it not a very remarkable fact? It
seems so to me, in my ignorance. I wish I could remember more distinctly
what I formerly read of Du Bois Raymond's results. My poor memory never
serves me for more than a vague guide. I really think you ought to try
Drosera. In a weak solution of phosphate of ammonia (viz. 1 gr. to 20
oz. of water) it will contract in about five minutes, and even more
quickly in pure warm water; but then water, I suppose, would prevent
your trial. I forget, but I think it contracts pretty quickly (i.e. in
an hour or two) with a large drop of a rather stronger solution of the
phosphate, or with an atom of raw meat on the disc of the leaf.

LETTER 718. TO J.D. HOOKER. October 31st, 1873.

Now I want to tell you, for my own pleasure, about the movements of
Desmodium.

1. When the plant goes to sleep, the terminal leaflets hang vertically
down, but the petioles move up towards the axis, so that the dependent
leaves are all crowded round it. The little leaflets never go to sleep,
and this seems to me very odd; they are at their games of play as late
as 11 o'clock at night and probably later. (718/1. Stahl ("Botanische
Zeitung," 1897, page 97) has suggested that the movements of the dwarf
leaflets in Desmodium serve to shake the large terminal leaflets, and
thus increase transpiration. According to Stahl's view their movement
would be more useful at night than by day, because stagnation of the
transpiration-current is more likely to occur at night.)

2. If the plant is shaken or syringed with tepid water, the terminal
leaflets move down through about an angle of 45 deg, and the petioles
likewise move about 11 deg downwards; so that they move in an opposite
direction to what they do when they go to sleep. Cold water or air
produces the same effect as does shaking. The little leaflets are not
in the least affected by the plant being shaken or syringed. I have no
doubt, from various facts, that the downward movement of the terminal
leaflets and petioles from shaking and syringing is to save them fr