analogous to the digestive fluid of an animal, was certainly a
remarkable discovery.

During this autumn of 1876 I shall publish on the 'Effects of
Cross and Self-Fertilisation in the Vegetable Kingdom.' This
book will form a complement to that on the 'Fertilisation of
Orchids,' in which I showed how perfect were the means for cross-
fertilisation, and here I shall show how important are the
results. I was led to make, during eleven years, the numerous
experiments recorded in this volume, by a mere accidental
observation; and indeed it required the accident to be repeated
before my attention was thoroughly aroused to the remarkable fact
that seedlings of self-fertilised parentage are inferior, even in
the first generation, in height and vigour to seedlings of cross-
fertilised parentage. I hope also to republish a revised edition
of my book on Orchids, and hereafter my papers on dimorphic and
trimorphic plants, together with some additional observations on
allied points which I never have had time to arrange. My
strength will then probably be exhausted, and I shall be ready to
exclaim "Nunc dimittis."

WRITTEN MAY 1ST, 1881.

'The Effects of Cross and Self-Fertilisation' was published in
the autumn of 1876; and the results there arrived at explain, as
I believe, the endless and wonderful contrivances for the
transportal of pollen from one plant to another of the same
species. I now believe, however, chiefly from the observations
of Hermann Muller, that I ought to have insisted more strongly
than I did on the many adaptations for self-fertilisation; though