* ‘Gardener’s Chronicle,’ 1874, p. 671.  Nearly similar observations were made in 1798 by B. S. Barton. [page 210]

wished, therefore, to ascertain whether camphor would render the leaves of Drosera more sensitive to mechanical irritation than they naturally are.  Six leaves were left in distilled water for 5 m. or 6 m., and then gently brushed twice or thrice, whilst still under water, with a soft camel-hair brush; but no movement ensued.  Nine leaves, which had been immersed in the above solution of camphor for the times stated in the following table, were next brushed only once with the same brush and in the same manner as before; the results are given in the table.  My first trials were made by brushing the leaves whilst still immersed in the solution; but it occurred to me that the viscid secretion round the glands would thus be removed, and the camphor might act more effectually on them.  In all the following trials, therefore, each leaf was taken out of the solution, waved for about 15 s. in water, then placed in fresh water and brushed, so that the brushing would not allow the freer access of the camphor; but this treatment made no difference in the results.

Column 1 :  Number of Leaves.  Column 2 :  Length of Immersion in the Solution of Camphor.  Column 3 :  Length of Time between the Act of Brushing and the Inflection of the Tentacles.  Column 4 :  Length of Time between the Immersion of the Leaves in the Solution and the First Sign of the Inflection of the Tentacles.

1 :  5 m. :  3 m. considerable inflection; 4 m. all the tentacles except 3 or 4 inflected. :  8 m.

2 :  5 m. :  6 m. first sign of inflection. :  11 m.

3 :  5 m. :  6 m. 30 s. slight inflection; 7 m. 30 s. plain inflection. :  11 m. 30 s.

4 :  4 m. 30 s. :  2 m. 30 s. a trace of inflection; 3 m. plain; 4 m. strongly marked. :  7 m.

5 :  4 m. :  2 m. 30 s. a trace of inflection; 3 m. plain inflection. :  6 m. 30 s.

6 :  4 m. :  2 m. 30 s. decided inflection; 3 m. 30 s. strongly marked. :  6 m. 30 s.

7 :  4 m. :  2 m. 30 s. slight inflection; 3 m. plain; 4 m. well marked. : 6 m. 30 s.

8 :  3 m. :  2 m. trace of inflection; 3 m. considerable, 6 m. strong inflection. :  5 m.

9 :  3 m. :  2 m. trace of inflection; 3 m. considerable, 6 m. strong inflection. :  5 m.

Other leaves were left in the solution without being brushed; one of these first showed a trace of inflection after 11 m.; a second after 12 m.; five were not inflected until 15 m. had [page 211] elapsed, and two not until a few minutes later.  On the other hand, it will be seen in the right-hand column of the table that most of the leaves subjected to the solution, and which were brushed, became inflected in a much shorter time.  The movement of the tentacles of some of these leaves was so rapid that it could be plainly seen through a very weak lens.