172 DROSEUA ROTITNDIFOLIA. [Chap. IX. 



fleeted 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. 



Two or three other experiments are worth giving. A large old 

 leaf, after being immersed for 10 m. in the solution, did not appear 

 likely to be soon inllected; so I brushed it, and in 2 ni. it began 

 to move, and in 3 m. was completely shut. Another leaf, after an- 

 immersion of 15 m., showed no signs of inflection, so was brushed, 

 and in 4 m. was grandly inflected. A third leaf, after an immersion 

 of 17 m., likewise showed no signs of inflection; it was then 

 brushed, but did not move for 1 hr.; so that here was a failure. 

 It was again brushed, and now in 9 m. a few tentacles became in- 

 flected; the failure therefore was not complete. 



We may conclude that a small dose of camphor in solution is a 

 powerful stimulant to Drosera. It not only soon excites the ten- 

 tacles to bend, but apparently renders the glands sensitive to a 

 touch, which by itself does not cause any movement. Or it may 

 be that a slight mechanical irritation not enough to cause any in- 

 flection yet gives some tendency to movement, and thus reinforces 

 the action of the camphor. This latter view would have appeared 

 to me the more probable one, had it not been shown by M. Vogel 

 that camphor is a stimulant in other ways to various plants and 

 seeds. 



Two plants bearing four or five leaves, and with their roots in 

 a little cup of water, were exposed to the vapour of some bits of 

 camphor (about as large as a filbert nut), under a vessel holding 

 ten fluid ounces. After 10 hrs. no inflection ensued; but the 

 glands appeared to be secreting more copiously. The leaves were 

 in a narcotised condition, for on bits of meat being placed on two 

 of them, there was no inflection in 3 hi-s. 15 m., and even after 13 

 l)rs. 15 m. only a few of the outer tentacles were slightly in- 

 flected; but this degree of movement shows that the leaves had 

 not been killed by an exposure during 10 hrs. to the vapour of 

 camphor. 



Oil of Caraway. Water is said to dissolve about a thousandth 

 part of its weight of this oil. A drop was added to an ounce of 

 water and the bottle occasionally shaken during a day; but many 

 minute globules remained undissolved. Five leaves were immersed 

 in this mixture; in from 4 m. to 5 m. there was some inflection, 

 which became moderately pronounced in two or three additional 

 minutes. After 14 m. all five leaves were well, and some of them 

 closely, inflected. After hrs. the glands were white, and much 

 mucus had been secreted. The leaves were now flaccid, of a 

 peculiar dull-red colour, and evidently dead. One of the leaves, 

 after an immersion of 4 m., was brushed, like the leaves in the 

 camphor, but this produced no efTect. A plant with its roots in 

 water was exposed under a 10-oz. vessel to the vapour of this oil, 

 and in 1 hr. 20 m. one leaf showe<l a trace of inflection. After 5 

 hrs. 20 m. the cover was taken ofl" and the leaves examined; one 

 had all its tentacles closely inflectefl. the second about half in the 

 same state; and the third all sub-inflected. The plant Mas left in 



