Cruger informed me from actual observation in the West Indies,
and as Delpino infers with much acuteness from the relative position of
the several parts of their flowers. (10/51. 'Ult. Osservaz. Dicogamia'
1868-69 page 188.) Mr. Farrer has also shown that the flowers of
Coronilla are curiously modified, so that bees may fertilise them whilst
sucking the fluid secreted from the outside of the calyx. (10/52.
'Nature' 1874 page 169.) It further appears probable from the
observations of the Reverend W.A. Leighton, that the fluid so abundantly
secreted by glands on the phyllodia of the Australian Acacia magnifica,
which stand near the flowers, is connected with their fertilisation.
(10/53. 'Annals and Magazine of Natural History' volume 16 1865 page 14.
In my work on the 'Fertilisation of Orchids' and in a paper subsequently
published in the 'Annals and Magazine of Natural History' it has been
shown that although certain kinds of orchids possess a nectary, no
nectar is actually secreted by it; but that insects penetrate the inner
walls and suck the fluid contained in the intercellular spaces. I
further suggested, in the case of some other orchids which do not
secrete nectar, that insects gnawed the labellum; and this suggestion
has since been proved true. Hermann Muller and Delpino have now shown
that some other plants have thickened petals which are sucked or gnawed
by insects, their fertilisation being thus aided.
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