188 DROSERA ROTUNDIFOLIA. (CHAF. X, 
water. On the other hand, in several cases in which tentacles 
became inflected after their glands had been cut off with 
sharp scissors, a distinct though moderate degree of aggre- 
gation supervened. 
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 
observed. 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 papillæ, 
which do not secrete, but have the power of absorption: 
These papillæ 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 
secretion had been excited. Hence I moistened them 
with saliva, solutions of ammonia, weak hydrochloric acid, 
and frequently 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 I never saw any true movement. I 
was led to make so many trials because, contrary to my 
previous experience, Nitschke statest that, after affixing 
* ‘Bot. Zeitung,’ 1860, p. 234. + Ibid., p. 437. 
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