because of its intrinsic scientific interest, but also because they are
almost the only letters which show Darwin in personal relation with a
younger man engaged in research under his supervision.)

[1862?]

To the best of my judgment, no subject is so important in relation to
theoretical natural science, in several respects, and likewise in itself
deserving investigation, as the effects of changed or unnatural conditions,
or of changed structure on the reproductive system. Under this point of
view the relation of well-marked but undoubted varieties in fertilising
each other requires far more experiments than have been tried. See in the
"Origin" the brief abstract of Gartner on Verbascum and Zea. Mr. W.
Crocker, lately foreman at Kew and a very good observer, is going at my
suggestion to work varieties of hollyhock. (150/2. Altheae species.
These experiments seem not to have been carried out.) The climate would be
too cold, I suppose, for varieties of tobacco. I began on cabbages, but
immediately stopped from early shedding of their pollen causing too much
trouble. Your knowledge would suggest some [plants]. On the same
principle it would be well to test peloric flowers with their own pollen,
and with pollen of regular flowers, and try pollen of peloric on regular
flowers--seeds being counted in each case. I have now got one seedling
from many crosses of a peloric Pelargonium by peloric pollen; I have two or
three seedlings from a peloric flower by pollen of regular flower. I have
ordered a peloric Antirrhinum (150/3. See "Variation of Animals and
Plants," Edition I., Volume II., page 70.) and the peloric Gloxinia, but I
much fear I shall never have time to try them. The Passiflora cases are
truly wonderful, like the Crinum cases (see "Origin"). (150/4. "Origin,"
Edition VI., page 238.) I have read in a German paper that some varieties
of potatoes (name not given) cannot be fertilised by [their] own pollen,