r train we will send to meet you. You will have to work like a
slave while you are here.

LETTER 728. TO J. JENNER WEIR.

(728/1. In 1870 Mr. Jenner Weir wrote to Darwin: "My brother has but
two kinds of laburnum, viz., Cytisus purpureus, very erect, and Cytisus
alpinus, very pendulous. He has several stocks of the latter grafted
with the purple one; and this year, the grafts being two years old,
I saw in one, fairly above the stock, about four inches, a raceme of
purely yellow flowers with the usual dark markings, and above them a
bunch of purely purple flowers; the branches of the graft in no way
showed an intermediate character, but had the usual rigid growth of
purpureus."

Early in July 1875, when Darwin was correcting a new edition of
"Variation under Domestication," he again corresponded with Mr. Weir on
the subject.)

Down, July 8th [1875].

I thank you cordially. The case interests me in a higher degree than
anything which I have heard for a very long time. Is it your brother
Harrison W., whom I know? I should like to hear where the garden is.
There is one other very important point which I am most anxious to
hear--viz., the nature of the leaves at the base of the yellow racemes,
for leaves are always there produced with the yellow laburnums, and I
suppose so in the case of C. purpureus. As the tree has produced yellow
racemes several times, do you think you could ask your brother to cut
off and send me by post in a box a small branch of the purple stock with
the pods or leaves of the yellow sport? (728/2. "The purple stock" here
means the supposed C. purpureus, on which a yellow-flowered branch was
borne.) This would be an immense favour, for then I would cut the point
of junction longitudinally and examine slice under the microscope, to be
able to state no trace of bud of yellow kind having been inserted. I do
not suspect anything of the kind, but it is sure to be said that your
brother's gardener, either by accident or fraud, inserted a bud. Under
this point of view it would be very good to gather from your brother how
many times the yellow sport has appeared. The case appears to me so
very important as to be worth any trouble. Very many thanks for all
assistance so kindly given.

I will of course send a copy of new edition of "Variation under
Domestication" when published in the autumn.

LETTER 729. TO J. JENNER WEIR.

(729/1. On July 9th Mr. Weir wrote to say that a branch of the Cytisus
had