234 DIONEA MUSCIPULA. [Cuap. XII. 
length being sufficiently rigid to support itself in a nearly 
horizontal line. The extremity was then brought by a slow 
movement laterally into contact with the tip of a filament, 
and the leaf instantly closed. On another occasion two or 
three touches of the same kind were necessary before any 
movement ensued. When we consider how flexible a fine 
hair is, we may form some idea how slight must be the touch 
given by the extremity of a piece, 1 inch in length, moved 
slowly. 
Although these filaments are so sensitive to a momentary 
and delicate touch, they are far less sensitive than the glands 
of Drosera to prolonged pressure. Several times I succeeded 
in placing on the tip of a filament, by the aid of a needle 
moved with extreme slowness, bits ot rather thick human 
hair, and these did not excite movement, although they were 
more than ten times as long as those which caused the ten- 
tacles of Drosera to bend; and although in this latter case 
they were largely supported by the dense secretion. On the 
other hand, the glands of Drosera may be struck with a needle 
or any hard object, once, twice, or even thrice, with consider- 
able force, and no movement ensues. This singular differenc 
in the nature of the sensitiveness of the filaments of Dionxa 
and of the glands of Drosera evidently stands in relation to 
the habits of the two plants. Ifa minute insect alights with 
its delicate feet on the glands of Drosera, it is caught by the 
viscid secretion, and the slight, though prolonged pressure, 
gives notice of the presence of prey, which is secured by the 
slow bending of the tentacles. On the other hand, the 
sensitive filaments of Dionæa are not viscid, and the capture 
of insects can be assured only by their sensitiveness to a 
momentary touch, followed by the rapid closure of the lobes.* 
As just stated, the filaments are not glandular, and do not 
secrete. Nor have they the power of absorption, as may be 
inferred from drops of a solution of carbonate of ammonia 
(one part to 146 of water), placed on two filaments, not pro- 
ducing any effect on the contents of their cells, nor causing 
the lobes to close. When, however, a small portion of a leaf 
with an attached filament was cut off and immersed in the 
* [Munk (Reichert and du Bois- covering them was removed. It is 
Reymond’s ‘Archiv.’ 1876, p. 105) remarkable that the change from a 
states that the leaves of his plants damp to a dry atmosphere should 
frequently closed when the bell-jar produce this effect.—F. D.] 
