antagonism to each other,
from your semi-sterile plants so that I may compare this comparative
growth with that of the offspring of English fertile plants. I have
forwarded your postscript about Passiflora, with the seeds, to Mr.
Farrer, who I am sure will be greatly obliged to you; the turning up of
the pendant flower plainly indicates some adaptation. When I next go to
London I will take up the specimens of butterflies, and show them to
Mr. Butler, of the British Museum, who is a learned lepidopterist
and interested on the subject. This reminds me to ask you whether you
received my letter [asking] about the ticking butterfly, described at
page 33 of my "Journal of Researches"; viz., whether the sound is in
anyway sexual? Perhaps the species does not inhabit your island. (682/2.
Papilio feronia, a Brazilian species capable of making "a clicking
noise, similar to that produced by a toothed wheel passing under a
spring catch."--"Journal," 1879, page 34.)

The case described in your last letter of the trimorphic monocotyledon
Pontederia is grand. (682/3. This case interested Darwin as the only
instance of heterostylism in Monocotyledons. See "Forms of Flowers,"
Edition II., page 183. F. Muller's paper is in the "Jenaische
Zeitschrift," 1871.) I wonder whether I shall ever have time to recur
to this subject; I hope I may, for I have a good deal of unpublished
material.

Thank you for telling me about the first-formed flower having additional
petals, stamens, carpels, etc., for it is a possible means of transition
of form; it seems also connected with the fact on which I have insisted
of peloric flowers being so often terminal. As pelorism is strongly
inherited (and [I] have just got a curious case of this in a leguminous
plant from India), would it not be worth while to fertilise some of
your early flowers having additional organs with pollen from a similar
flower, and see whether you could not make a race thus characterised?
(682/4. See Letters 588, 589. Also "Variation under Domestication,"
Edition II., Volume I., pages 388-9.) Some of your Abutilons have
germinated, but I have been very unfortunate with most of your seed.

You will remember having given me in a former letter an account of
a very curious popular belief in regard to the subsequent progeny
of asses, which have borne mules; and now I have another case almost
exactly like that of Lord Morton's mare, in which it is said the shape
of the hoofs in the subseq