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INSECTIVOROUS PLANTS.
CHAPTER I.
DROSERA ROTUNDIFOLIA, OR THE COMMON SUN-DEW.
Number of insects captured — Description of the leaves and their appendages or tentacles — Preliminary sketch of the action of the various parts, and of the manner in which insects are captured — Duration of the inflection of the tentacles — Nature of the secretion — Manner in which insects are carried to the centre of the leaf — Evidence that the glands have the power of absorption — Small size of the roots.
During the summer of 1860, I was surprised by finding how large a number of insects were caught by the leaves of the common sun-dew (Drosera rotundifolia) on a heath in
Sussex. I had heard that insects were thus caught, but knew nothing further on the subject.[1] I gathered by chance
- ↑ As Dr. Nitschke has given (‘Bot. Zeitung,’ 1860, p. 229) the bibliography of Drosera, I need not here go into details. Most of the notices published before 1860 are brief and unimportant. The oldest paper seems to have been one of the most valuable, namely, by Dr. Roth. In 1782. [In the ‘Quarterly Journal of Science and Art,’ 1829, G. T. Burnett expressed his belief that Drosera profits by the absorption of nutritive matter from the captured Insects. F. I).] There Is also an Interesting though short account of the habits of Drosera by Dr. Milde, In the ‘Bot. Zeitung,’ 1852, p. 540. In 185.5, in the ‘Annales des Sc. nat. bot.,’ tom. III. pp. 297 and 304, MM. Grœnland and Trécul each published papers, with figures, on the structure of the leaves; but M. Trécul went so far as to doubt whether they possessed any power of movement. Dr. Nitschke's papers In the ‘Bot. Zeitung,’ for 1860 and 1861 are by far the most important ones which have been published, both on the habits and structure of this plant; and I shall frequently have occasion to quote from them. His discussions on several points, for instance on the transmission of an excitement from one part of the leaf to another, are excellent. On Dec. 11, 1862, Mr. J. Scott read a paper before the Botanical Society of Edinburgh, which was published in the ‘Gardener's Chronicle,’ 1863, p. 30. Mr. Scott shows that gentle irritation of the hairs, as well as insects placed on the disc of the leaf, cause the hairs to bend inwards. Mr. A. W. Bennett also gave another interesting account of the movements of the leaves before the British Association for 1873. In this same year Dr. Warming published an essay. In which he describes the structure of the socalled hairs, entitled, "Sur la Différence entre les Trichomes," &c., extracted from the proceedings of the Soc. d'Hist. Nat. de Copenhague. I shall also have
