above letter from Scott.
In the first edition of "Fertilisation of Orchids" (page 209) he assumed
that the sexes in Acropera, as in Catasetum, were separate. In the
second edition (page 172) he writes: "I was, however, soon convinced
of my error by Mr. Scott, who succeeded in artificially fertilising
the flowers with their own pollen. A remarkable discovery by Hildebrand
(633/2. "Bot. Zeitung," 1863 and 1865.), namely, that in many orchids
the ovules are not developed unless the stigma is penetrated by the
pollen-tubes...explains the state of the ovarium in Acropera, as
observed by me." In regard to this subject see Letter 608.)

Down, November 12th, 1862.

I thank you most sincerely for your kindness in writing to me, and for
[your] very interesting letter. Your fact has surprised me greatly, and
has alarmed me not a little, for if I am in error about Acropera I may
be in error about Catasetum. Yet when I call to mind the state of
the placentae in A. luteola, I am astonished that they should produce
ovules. You will see in my book that I state that I did not look at the
ovarium of A. Loddigesii. Would you have the kindness to send me word
which end of the ovarium is meant by apex (that nearest the flower?),
for I must try and get this species from Kew and look at its ovarium.
I shall be extremely curious to hear whether the fruit, which is now
maturing, produces a large number of good and plump seed; perhaps you
may have seen the ripe capsules of other Vandeae, and may be able
to form some conjecture what it ought to produce. In the young,
unfertilised ovaria of many Vandeae there seemed an infinitude of
ovules. In desperation it occurs to me as just possible, as almost
everything in nature goes by gradation, that a properly male flower
might occasionally produce a few seeds, in the same manner as female
plants sometimes produce a little pollen. All your remarks seem to me
excellent and very interesting, and I again thank you for your kindness
in writing to me. I am pleased to observe that my description of the
structure of Acropera seems to agree pretty well with what you have
observed. Does it not strike you as very difficult to understand
how insects remove the pollinia and carry them to the stigmas? Your
suggestion that the mouth of the stigmatic cavity may become charged
with viscid matter and thus secure the pollinia, and that the
pollen-tubes may then protrude, seems very ingenious and new to me; but
it would