34 DROSERA ROTUNDIFOLIA. CHAP. IT 



The Inflection of the Exterior Tentacles, when their Glands 

 are excited by Repeated Touches. 



We have already seen, that, if the central glands 

 are excited by being gently brushed, they trans- 

 mit a motor impulse to the exterior tentacles, 

 causing them to bend ; and we have now to con- 

 sider the effects 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 thousand- 

 fold greater pressure than the weight of the above 

 described particles, not a tentacle moved. On 

 another occasion 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 ten- 

 tacles ; 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 efficient 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 

 became 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 

 on them. On another occasion I gave a single for- 



