y increased and becomes feebly acid,
which was not the case before. I have been astonished and much disturbed
by finding that cabbage seeds excite a copious secretion, and am now
endeavouring to discover what this means. (724/2. Clearly it had not
occurred to Darwin that seeds may supply nitrogenous food as well as
insects: see "Insectivorous Plants," page 390.) Probably in a few days'
time I shall have to beg a little information from you, so I will write
no more now.

P.S. I heard from Asa Gray a week ago, and he tells me a beautiful fact:
not only does the lid of Sarracenia secrete a sweet fluid, but there
is a line or trail of sweet exudation down to the ground so as to tempt
insects up. (724/3. A dried specimen of Sarracenia, stuffed with cotton
wool, was sometimes brought from his study by Mr. Darwin, and made the
subject of a little lecture to visitors of natural history tastes.)

LETTER 725. TO W. THISELTON-DYER. Down, June 23rd, 1874.

I wrote to you about a week ago, thanking you for information on cabbage
seeds, asking you the name of Luzula or Carex, and on some other points;
and I hope before very long to receive an answer. You must now, if you
can, forgive me for being very troublesome, for I am in that state in
which I would sacrifice friend or foe. I have ascertained that bits
of certain leaves, for instance spinach, excite much secretion in
Pinguicula, and that the glands absorb matter from the leaves. Now this
morning I have received a lot of leaves from my future daughter-in-law
in North Wales, having a surprising number of captured insects on them,
a good many leaves, and two seed-capsules. She informs me that the
little leaves had excited secretion; and my son and I have ascertained
this morning that the protoplasm in the glands beneath the little leaves
has undoubtedly undergone aggregation. Therefore, absurd as it
may sound, I am prepared to affirm that Pinguicula is not only
insectivorous, but graminivorous, and granivorous! Now I want to beg you
to look under the simple microscope at the enclosed leaves and seeds,
and, if you possibly can, tell me their genera. The little narrow leaves
are remarkable (725/1. Those of Erica tetralix.); they are fleshy, with
the edges much curled from the axis of the plant, and bear a few long
glandular hairs; these grow in little tufts. These are the commonest in
Pinguicula, and seem to afford most nutritious matter. A second leaf is
like a miniature sycamore