treated never
swelling.

Fourthly: Can you give me any very hairy Saxifraga (for their functions)
[i.e. the functions of the hairs]?

I send you a resume of my requests, to save you trouble. Nor would I ask
for so much aid if I did not think all these points well worth trying to
investigate.

My dear old friend, a letter from you always does me a world of good.
And, the Lord have mercy on me, what a return I make.

LETTER 602. TO J.D. HOOKER. Down, October 4th [1861].

Will you have the kindness to read the enclosed, and look at the
diagram. Six words will answer my question. It is not an important
point, but there is to me an irresistible charm in trying to make out
homologies. (602/1. In 1880 he wrote to Mr. Bentham: "It was very kind
of you to write to me about the Orchideae, for it has pleased me to an
extreme degree that I could have been of the least use to you about the
nature of the parts."--"Life and Letters," III., page 264.) You know
the membranous cup or clinandrum, in many orchids, behind the stigma and
rostellum: it is formed of a membrane which unites the filament of the
normal dorsal anther with the edges of the pistil. The clinandrum is
largely developed in Malaxis, and is of considerable importance in
retaining the pollinia, which as soon as the flower opens are quite
loose.

The appearance and similarity of the tissues, etc., at once gives
suspicion that the lateral membranes of the clinandrum are the two other
and rudimentary anthers, which in Orchis and Cephalanthera, etc., exist
as mere papillae, here developed and utilised.

Now for my question. Exactly in the middle of the filament of the
normal anther, and exactly in the middle of the lateral membrane of the
clinandrum, and running up to the same height, are quite similar bundles
of spiral vessels; ending upwards almost suddenly. Now is not this
structure a good argument that I interpret the homologies of the sides
of clinandrum rightly? (602/2. Though Robert Brown made use of the
spiral vessels of orchids, yet according to Eichler, "Bluthendiagramme,"
1875, Volume I., page 184, Darwin was the first to make substantial
additions to the conclusions deducible from the course of the vessels in
relation to the problem of the morphology of these plants. Eichler
gives Darwin's diagram side by side with that of Van Tieghem without
attempting to decide between the differences in detail by which they are
characterised.)

I find that the grea