IXSECTIYOROUS PLANTS. 



CHAPTER I. 



DROSEBA ROTUNDIFOLIA, OB THE COMMON SUN-DEW. 



Number of insects captured Description of the leaves and their append- 

 ages 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.* I gathered by chance 



* As Dr. Xitschke has given 

 (' Bot. Zeltung,' 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 cap- 

 tured Insects. F. I).] There Is 

 also an Interesting though short 

 account of the habits of Drosera 

 by Dr. Mllde, In the ' Bot. Zelt- 

 ung,' 1852, p. 540. In 185.5, In 

 the ' Annales des Sc. nat. bot.,' 

 torn. 111. pp. 297 and 304, MM. 

 -Greenland and Tr^cul each pub- 

 lished papers, with figures, on 

 the structure of the leaves; but 

 M. Tr^cul went so far as to 

 doubt whether they possessed 

 any power of movement. Dr. 

 Nltscnke's papers In the ' Bot. 

 Zeltung 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 sev- 

 eral points, for instance on the 

 transmission of an excitement 

 from one part of the leaf to an- 

 other, are excellent. On Dec. 

 11, 1862, Mr. J. Scott read a 

 paper before the Botanical So- 

 ciety 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 an- 

 other Interesting account of the 

 movements of the leaves before 

 the British As.socIatlon for 1873. 

 In this same year Dr. Warming 



Subllshed an essay. In which he 

 escribes the structure of the so- 

 called hairs, entitled, " Sur la 

 Difference entre les 'Trlchomes," 

 &c., extracted from the proceed- 

 ings of the Soc. d'HIst. Nat. de 

 Copenhague. I shall also have 



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