The Effects of Cross and Self-Fertilisation in the Vegetable Kingdom | Page 7

after which time it
resumes its original position. (1/2. 'Botanische Zeitung' 1866 page 129.)
Thus the stigma cannot be fertilised by pollen from the same flower,
but only by that brought by a moth from some other flower. Endless
other beautiful contrivances for this same purpose could be specified.
Long before I had attended to the fertilisation of flowers, a remarkable
book appeared in 1793 in Germany, 'Das Entdeckte Geheimniss der
Natur,' by C.K. Sprengel, in which he clearly proved by innumerable
observations, how essential a part insects play in the fertilisation of
many plants. But he was in advance of his age, and his discoveries were
for a long time neglected. Since the appearance of my book on Orchids,
many excellent works on the fertilisation of flowers, such as those by
Hildebrand, Delpino, Axell and Hermann Muller, and numerous shorter
papers, have been published. (1/3. Sir John Lubbock has given an
interesting summary of the whole subject in his 'British Wild Flowers
considered in relation to Insects' 1875. Hermann Muller's work 'Die
Befruchtung der Blumen durch Insekten' 1873, contains an immense
number of original observations and generalisations. It is, moreover,
invaluable as a repertory with references to almost everything which
has been published on the subject. His work differs from that of all
others in specifying what kinds of insects, as far as known, visit the
flowers of each species. He likewise enters on new ground, by showing
not only that flowers are adapted for their own good to the visits of
certain insects; but that the insects themselves are excellently adapted
for procuring nectar or pollen from certain flowers. The value of H.
Muller's work can hardly be over-estimated, and it is much to be
desired that it should be translated into English. Severin Axell's work is
written in Swedish, so that I have not been able to read it.) A list would
occupy several pages, and this is not the proper place to give their titles,
as we are not here concerned with the means, but with the results of
cross-fertilisation. No one who feels interest in the mechanism by

which nature effects her ends, can read these books and memoirs
without the most lively interest.
From my own observations on plants, guided to a certain extent by the
experience of the breeders of animals, I became convinced many years
ago that it is a general law of nature that flowers are adapted to be
crossed, at least occasionally, by pollen from a distinct plant. Sprengel
at times foresaw this law, but only partially, for it does not appear that
he was aware that there was any difference in power between pollen
from the same plant and from a distinct plant. In the introduction to his
book (page 4) he says, as the sexes are separated in so many flowers,
and as so many other flowers are dichogamous, "it appears that nature
has not willed that any one flower should be fertilised by its own
pollen." Nevertheless, he was far from keeping this conclusion always
before his mind, or he did not see its full importance, as may be
perceived by anyone who will read his observations carefully; and he
consequently mistook the meaning of various structures. But his
discoveries are so numerous and his work so excellent, that he can well
afford to bear a small amount of blame. A most capable judge, H.
Muller, likewise says: "It is remarkable in how very many cases
Sprengel rightly perceived that pollen is necessarily transported to the
stigmas of other flowers of the same species by the insects which visit
them, and yet did not imagine that this transportation was of any
service to the plants themselves." (1/4. 'Die Befruchtung der Blumen'
1873 page 4. His words are: "Es ist merkwurdig, in wie zahlreichen
Fallen Sprengel richtig erkannte, dass durch die Besuchenden Insekten
der Bluthenstaub mit Nothwendigkeit auf die Narben anderer Bluthen
derselben Art ubertragen wird, ohne auf die Vermuthung zu kommen,
dass in dieser Wirkung der Nutzen des Insektenbesuches fur die
Pflanzen selbst gesucht werden musse.")
Andrew Knight saw the truth much more clearly, for he remarks,
"Nature intended that a sexual intercourse should take place between
neighbouring plants of the same species." (1/5. 'Philosophical
Transactions' 1799 page 202.) After alluding to the various means by
which pollen is transported from flower to flower, as far as was then
imperfectly known, he adds, "Nature has something more in view than

that its own proper males would fecundate each blossom." In 1811
Kolreuter plainly hinted at the same law, as did afterwards another
famous hybridiser of plants, Herbert. (1/6. Kolreuter 'Mem. de l'Acad.
de St. Petersbourg' tome 3 1809 published 1811 page 197. After
showing how well the Malvaceae are adapted for cross-fertilisation, he
asks, "An id aliquid in recessu