tried to
take a small portion out of the water, you will remember that it is most
difficult. I believe all the birds in the world might alight every day
on the spawn of batrachians, and never transport a single ovum. With
respect to the young of molluscs, undoubtedly if the bird to which they
were attached alighted on the sea, they would be instantly killed; but
a land-bird would, I should think, never alight except under dire
necessity from fatigue. This, however, has been observed near Heligoland
(205/1. Instances are recorded by Gatke in his "Heligoland as an
Ornithological Observatory" (translated by Rudolph Rosenstock,
Edinburgh, 1895) of land-birds, such as thrushes, buntings, finches,
etc., resting for a short time on the surface of the water. The
author describes observations made by himself about two miles west of
Heligoland (page 129).); and land-birds, after resting for a time on the
tranquil sea, have been seen to rise and continue their flight. I cannot
give you the reference about Heligoland without much searching. This
alighting on the sea may aid you in your unexpected difficulty of the
too-easy diffusion of land-molluscs by the agency of birds. I much
enjoyed my morning's talk with you.

LETTER 206. TO F. HILDEBRAND. Down, January 5th [1868].

I thank you for your letter, which has quite delighted me. I sincerely
congratulate you on your success in making a graft-hybrid (206/1. Prof.
Hildebrand's paper is in the "Bot. Zeitung," 1868: the substance is
given in "Variation of Animals and Plants," Edition II., Volume I., page
420.), for I believe it to be a most important observation. I trust that
you will publish full details on this subject and on the direct action
of pollen (206/2. See Prof. Hildebrand, "Bot. Zeitung," 1868, and
"Variation of Animals and Plants," Edition II., Volume I., page 430.
A yellow-grained maize was fertilised with pollen from a brown-grained
one; the result was that ears were produced bearing both yellow and
dark-coloured grains.): I hope that you will be so kind as to send me a
copy of your paper. If I had succeeded in making a graft-hybrid of the
potato, I had intended to raise seedlings from the graft-hybrid and
from the two parent-forms (excluding insects) and carefully compare the
offspring. This, however, would be difficult on account of the sterility
and variability of the potato. When in the course of a few months you
receive my second volume (206/3. This sentence may