188 DROSERA ROTUNDIFOLIA. [Chap. X. 



like manner the protoplasm does not become aggregated when 

 a leaf is instantly killed by being dipped into boiling water. 

 On the other hand, in several cases in which tentacles became 

 inflected after their glands had been cut off with sharp scis- 

 sors, a distinct though moderate degree of aggregation super- 

 vened. 



The pedicels of the tentacles were roughly and repeatedly 

 rubbed; raw meat or other exciting substances were placed 

 on them, both on the upper surface near the base and else- 

 where, but no distinct movement ensued. Some bits of 

 meat, after being left for a considerable time on the pedicels, 

 were pushed upwards, so as just to touch the glands, and in 

 a minute the tentacles began to bend. I believe that the 

 blade of the leaf is not sensitive to any stimulant. I drove 

 the point of a lancet through the blades of several leaves, 

 and a needle three or four times through nineteen leaves : in 

 the former case no movement ensued; but about a dozen of 

 the leaves which were repeatedly pricked had a few tentacles 

 irregularly inflected. As, however, their backs had to be 

 supported during the operation, some of the outer glands, as 

 well as those on the disc, may have been touched; and this 

 perhaps sufficed to cause the slight degree of movement ob- 

 served. Nitschke* says that cutting and pricking the leaf 

 does not excite movement. The petiole of the leaf is quite 

 insensible. 



The backs of the leaves bear numerous minute papillee, 

 which do not secrete, but have the power of absorption. 

 These papillte are, I believe, rudiments of formerly existing 

 tentacles together with their glands. Many experiments 

 were made to ascertain whether the backs of the leaves could 

 be irritated in any way, thirty-seven leaves being thus tried. 

 Some were rubbed for a long time with a blunt needle, and 

 drops of milk and other exciting fluids, raw meat, crushed 

 flies, and various substances, placed on others. These sub- 

 stances were apt soon to become dry, showing that no secre- 

 tion had been excited. Ilence I moistened them with saliva, 

 solutions of ammonia, weak hydrochloric acid, and frequent- 

 ly with the secretion from the glands of other leaves. I also 

 kept some leaves, on the backs of which exciting objects had 

 been placed, under a damp bell-glass; but with all my care 



> ' Dot. Zvltuug,' 18G0, p. 234. 



