s the interest which
he felt in the question:--

"I was delighted with Paget's essay (757/2. An address on "Elemental
Pathology," delivered before the British Medical Association, August
1880, and published in the Journal of the Association.); I hear that
he has occasionally attended to this subject from his youth...I am very
glad he has called attention to galls: this has always seemed to me a
profoundly interesting subject; and if I had been younger would take it
up."

His interest in this subject was connected with his ever-present wish
to learn something of the causes of variation. He imagined to himself
wonderful galls caused to appear on the ovaries of plants, and by these
means he thought it possible that the seed might be influenced, and thus
new varieties arise. (757/3. There would have been great difficulties
about this line of research, for when the sexual organs of plants
are deformed by parasites (in the way he hoped to effect by poisons)
sterility almost always results. See Molliard's "Les Cecidies Florales,"
"Ann. Sci. Nat." 1895, Volume I., page 228.) He made a considerable
number of experiments by injecting various reagents into the tissues of
leaves, and with some slight indications of success. (757/4. The above
passage is reprinted, with alterations, from "Life and Letters," III.,
page 346.)

The following letter to the late Sir James Paget refers to the same
subject.)

Down, November 14th, 1880.

I am very much obliged for your essay, which has interested me greatly.
What indomitable activity you have! It is a surprising thought that the
diseases of plants should illustrate human pathology. I have the German
"Encyclopaedia," and a few weeks ago told my son Francis that the
article on the diseases of plants would be well worth his study; but I
did not know it was written by Dr. Frank, for whom I entertain a high
respect as a first-rate observer and experimentiser, though for some
unknown reason he has been a good deal snubbed in Germany. I can give
you one good case of regrowth in plants, recently often observed by me,
though only externally, as I do not know enough of histology to follow
out details. It is the tip of the radicle of a germinating common bean.
The case is remarkable in some respects, for the tip is sensitive to
various stimuli, and transmits an order, causing the upper part of
the radicle to bend. When the tip (for a length of about 1 mm.) is cut
transversely off, the radicle is