CHAP. IX. ESSENTIAL OILS, ETC. 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 move- 

 ment 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 largo 

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

 appear likely to be soon inflected ; so I brushed it, and in 2 m. 

 it began to move, and in 3 m. was completely shut. Another 

 leaf, after an immersion of 15 m., showed no signs of inflection, 

 BO was brushed, and in 4 m. was grandly inflected. A third leaf, 

 after an immersion of 17 m., likewise showed no signs of in- 

 flection ; 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 inflected ; 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 

 inflection 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 vaponr 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 hrs. 

 15 m., and even after 13 hrs. 15 m. only a few of the outer 

 tentacles were slightly inflected; 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 wag 

 wine inflection, which became moderately pronounced in two 01 



