ke of expression. From this time forward I
occasionally attended to the subject, both with respect to man and our
domesticated animals. My book sold largely; 5267 copies having been
disposed of on the day of publication.

In the summer of 1860 I was idling and resting near Hartfield, where two
species of Drosera abound; and I noticed that numerous insects had been
entrapped by the leaves. I carried home some plants, and on giving them
insects saw the movements of the tentacles, and this made me think
it probable that the insects were caught for some special purpose.
Fortunately a crucial test occurred to me, that of placing a large
number of leaves in various nitrogenous and non-nitrogenous fluids of
equal density; and as soon as I found that the former alone excited
energetic movements, it was obvious that here was a fine new field for
investigation.

During subsequent years, whenever I had leisure, I pursued my
experiments, and my book on 'Insectivorous Plants' was published in July
1875--that is, sixteen years after my first observations. The delay in
this case, as with all my other books, has been a great advantage to me;
for a man after a long interval can criticise his own work, almost as
well as if it were that of another person. The fact that a plant should
secrete, when properly excited, a fluid containing an acid and ferment,
closely 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 ex