all, and it occurs to me as possible,
though very improbable, that it would be different with a larger plant
with perhaps larger leaves. Would you some day get a gardener to syringe
violently, with water kept in a hothouse, a branch on one of your
largest logwood plants and observe [whether?] leaves move together
towards the apex of leaf?

By the way, what astonishing nonsense Mr. Andrew Murray has been
writing about leaves and carbonic acid! I like to see a man behaving
consistently...

What a lot I have scribbled to you!

(FIGURE 13. Leaf of Trifolium resupinatum (from a drawing by Miss
Pertz).)

LETTER 740. TO W. THISELTON-DYER. [August, 1877.]

There is no end to my requests. Can you spare me a good plant (or even
two) of Oxalis sensitiva? The one which I have (formerly from Kew) has
been so maltreated that I dare not trust my results any longer.

Please give the enclosed to Mr. Lynch. (740/1. Mr. Lynch, now Curator
of the Cambridge Botanic Garden, was at this time in the R. Bot. Garden,
Kew. Mr. Lynch described the movements of Averrhoa bilimbi in the "Linn.
Soc. Journ," Volume XVI., page 231. See also "The Power of Movement in
Plants," page 330.) The spontaneous movements of the Averrhoa are very
curious.

You sent me seeds of Trifolium resupinatum, and I have raised plants,
and some former observations which I did not dare to trust have proved
accurate. It is a very little fact, but curious. The half of the lateral
leaflets (marked by a cross) on the lower side have no bloom and are
wetted, whereas the other half has bloom and is not wetted, so that the
two sides look different to the naked eye. The cells of the eipdermis
appear of a different shape and size on the two sides of the leaf
[Figure 13].

When we have drawings and measurements of cells made, and are sure of
our facts, I shall ask you whether you know of any case of the same leaf
differing histologically on the two sides, for Hooker always says you
are a wonderful man for knowing what has been made out.

(740/2. The biological meaning of the curious structure of the leaves of
Trifolium resupinatum remains a riddle. The stomata and (speaking from
memory) the trichomes differ on the two halves of the lateral leaflets.)

LETTER 741. TO L. ERRERA.

(741/1. Professor L. Errera, of Brussels wrote, as a student, to Darwin,
asking permission to send the MS. of an essay by his friend S. Gevaert
and himself on cross and self-fertilisation, a