ut Mertensia. The former plant has begun
to make new leaves, to my great surprise, so that I shall be now well
supplied. We have worked so well with the Averrhoa that unless the
second species arrives in a very good state it would be superfluous to
send it. I am heartily glad that you and Mrs. Dyer are going to have
a holiday. I will look at you as a dead man for the next month, and
nothing shall tempt me to trouble you. But before you enter your grave
aid me if you can. I want seeds of three or four plants (not Leguminosae
or Cruciferae) which produce large cotyledons. I know not in the least
what plants have large cotyledons. Why I want to know is as follows: The
cotyledons of Cassia go to sleep, and are sensitive to a touch; but what
has surprised me much is that they are in constant movement up and down.
So it is with the cotyledons of the cabbage, and therefore I am very
curious to ascertain how far this is general.

LETTER 743. TO W. THISELTON-DYER. Down, October 11th [1877].

The fine lot of seeds arrived yesterday, and are all sown, and will be
most useful. If you remember, pray thank Mr. Lynch for his aid. I had
not thought of beech or sycamore, but they are now sown.

Perhaps you may like to see a rough copy of the tracing of movements
of one of the cotyledons of red cabbage, and you can throw it into
the fire. A line joining the two cotyledons stood facing a north-east
window, and the day was uniformly cloudy. A bristle was gummed to one
cotyledon, and beyond it a triangular bit of card was fixed, and in
front a vertical glass. A dot was made in the glass every quarter or
half hour at the point where the end of the bristle and the apex of card
coincided, and the dots were joined by straight lines. The observations
were from 10 a.m. to 8.45 p.m. During this time the enclosed figure was
described; but between 4 p.m. and 5.38 p.m. the cotyledon moved so that
the prolonged line was beyond the limits of the glass, and the course
is here shown by an imaginary dotted line. The cotyledon of Primula
sinensis moved in closely analogous manner, as do those of a Cassia.
Hence I expect to find such movements very general with cotyledons,
and I am inclined to look at them as the foundation for all the other
adaptive movements of leaves. They certainly are of the so-called sleep
of plants.

I hope I have not bothered you. Do not answer. I am all on fire at the
work.

I have had a short and very prosperous note from A