been despatched to Down. The present letter was doubtless
written after Darwin had examined the specimen. In "Variation under
Domestication," Edition II., Volume I., page 417, note, he gives for a
case recorded in the "Gardeners' Chronicle" in 1857 the explanation here
offered (viz. that the graft was not C. purpureus but C. Adami), and
adds, "I have ascertained that this occurred in another instance." This
second instance is doubtless Mr. Weir's.)

Down, July 10th, 1875.

I do not know how to thank you enough; pray give also my thanks and kind
remembrances to your brother. I am sure you will forgive my expressing
my doubts freely, as I well know that you desire the truth more than
anything else. I cannot avoid the belief that some nurseryman has sold
C[ytisus] Adami to your brother in place of the true C. purpureus. The
latter is a little bush only 3 feet high (Loudon), and when I read your
account, it seemed to me a physical impossibility that a sporting branch
of C. alpinus could grow to any size and be supported on the extremely
delicate branches of C. purpureus. If I understand rightly your letter,
you consider the tuft of small shoots on one side of the sporting C.
alpinus from Weirleigh as C. purpureus; but these shoots are certainly
those of C. Adami. I earnestly beg you to look at the specimens
enclosed. The branch of the true C. purpureus is the largest which
I could find. If C. Adami was sold to your brother as C. purpureus,
everything is explained; for then the gardener has grafted C. Adami on
C. alpinus, and the former has sported in the usual manner; but has not
sported into C. purpureus, only into C. alpinus. C. Adami does not sport
less frequently into C. purpureus than into C. alpinus. Are the purple
flowers borne on moderately long racemes? If so, the plant is certainly
C. Adami, for the true C. purpureus bears flowers close to the branches.
I am very sorry to be so troublesome, but I am very anxious to hear
again from you.

C. purpureus bears "flowers axillary, solitary, stalked."

P.S.--I think you said that the purple [tree] at Weirleigh does not
seed, whereas the C. purpureus seeds freely, as you may see in enclosed.
C. Adami never produces seeds or pods.

LETTER 730. TO E. HACKEL.

(730/1. The following extract refers to Darwin's book on "Cross and
Self-Fertilisation.")

November 13th, 1875.

I am now busy in drawing up an account of ten years' experiments in the
growth and fertility