[16]

Light

Left Hand Tracing II

[16v]

9

Introduction

cross-fertilisation. The case of Posoqueria fragrans (one of the Rubiaceæ) is as wonderful as that of the most wonderful orchid. The stamens, according to Fritz Müller* (*Botanische Zeitung. 1866. p. 129) are irritable, so that as soon as a moth visits the a flowers the anthers explodes and it becomes dusted cover the insect with pollen; ; one of the filaments which is broader than the others, then moves, and as it has been rendered broad for this special purpose, it keeps closes the flower closed for about twelve hours, until it moves away again after which time it resumes its original position. Thus the stigma cannot be fertilised by pollen from the same flower, but only by that brought by a moth from another flower. Endless other beautiful contrivances for this same purpose could be specified.

Long before I had attended to the fertilisation of flowers, a remarkable work appeared in 1793 in Germany, 'Das entdeckte Geheimnis der Natur,' by C. K. Sprengel, in which he clearly proved in 1791 by innumerable observations on many plants how

[Autobiography CUL-DAR26.1-121, p. 100: "'I attended to the subject more or less during every subsequent summer; & my interest in it was greatly enhanced by having procured & read in November 1841, through the advice of Robert Brown, a copy of C. K. Sprengel's1 wonderful book, "Das entdeckte Geheimnis der Natur.'"]

[Cross and self fertilisation, p. 5: "Papilionaceous flowers, as described by various authors—for instance, by Mr. T.H. Farrer—offer innumerable curious adaptations for cross-fertilisation. The case of Posoqueria fragrans (one of the Rubiaceae), is as wonderful as that of the most wonderful orchid. The stamens, according to Fritz Müller,* are irritable, so that as soon as a moth visits a flower, the anthers explode and cover the insect with pollen; one of the filaments which is broader than the others then moves and closes the flower for about twelve hours, after which time it resumes its original position. 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."]