80 DROSERA ROTUNDIFOLIA, [Chap. II. 



to the exterior tentacles, causing them to bend ; and we have 

 now to consider the efccts which follow from the glands of 

 the exterior tentacles being themselves touched. On several 

 occasions, a large number of glands were touched only once 

 with a needle or fine brush, hard enough to bend the whole 

 flexible tentacle; and, though this must have caused a thou- 

 sand-fold greater pressure than the weight of the above- 

 described particles, not a tentacle moved. On another oc- 

 casion forty-five glands on eleven leaves were touched once, 

 twice, or even thrice, with a needle or stiff bristle. This was 

 done as quickly as possible, but with force sufficient to bend 

 the tentacles; yet only six of them became inflected, three 

 plainly, and three in a slight degree. In order to ascertain 

 whether these tentacles which were not affected were in an 

 eflScient state, bits of meat were placed on ten of them, and 

 they all soon became greatly incurved. On the other hand, 

 when a large number of glands were struck four, five, or six 

 times with the same force as before, a needle or sharp splinter 

 of glass being used, a much larger proportion of tentacles be- 

 came inflected; but the result was so uncertain as to seem 

 capricious. For instance, I struck in the above manner 

 three glands, which happened to be extremely sensitive, and 

 all three were inflected almost as quickly as if bits of meat 

 had been placed upon them. On another occasion I gave 

 a single forcible touch to a considerable number of glands, 

 and not one moved ; but these same glands, after an interval 

 of some hours, being touched four or five times with a needle, 

 several of the tentacles soon became inflected. 



The fact of a single touch or even of two or three touches 

 not causing inflection must be of some service to the plant; 

 as, during stormy weather, the glands cannot fail to be oc- 

 casionally touched by the tall blades of grass, or by other 

 plants growing near; and it would be a great evil if the 

 tentacles were thus brought into action, for the act of re- 

 expansion takes a considerable time, and until the tentacles 

 are re-expandcd they cannot catch prey. On the other hand, 

 extreme sensitiveness to slight pressure is of the highest 

 service to the plant; for, as we have seen, if the delicate 

 feet of a minute struggling insect press ever so lightly on 

 the surfaces of two or three glands, the tentacles bearing 

 these glands soon curl inwards and carry the insect with 



