LE ETE I TT a TEL EY a 
Cuar. XII.] SENSITIVENESS OF FILAMENTS. ase 
absorption. Minute projections, formed of eight divergent 
arms of a reddish-brown or orange colour, and appearing 
under the microscope like elegant little flowers, are scattered 
in considerable numbers over the footstalk, the backs of the 
leaves, and the spikes, with a few on the upper surface of the 
lobes. These octofid projections are no doubt homologous 
with the papille on the leaves of Drosera rotundifolia. There 
are also a iew very minute, simple, pointed hairs,* about 
17407 Of an inch (+0148 mm.) in lengih on the backs of the 
eaves, 
The sensitive filamentst are formed of several rows of 
elongated cells, filled with purplish fluid. They are a little 
above the >} of an inch in length; are thin and delicate, and 
taper toa point. I examined the bases of several, making 
sections of them, but no trace of the entrance of any vessel 
could be seen. The apex is sometimes bifid or even trifid, 
owing to a slight separation between the terminal pointed 
cells. Towards the base there is constriction, formed of 
broader cells, beneath which there is an articulation, supported 
on an enlarged base, consisting of differently shaped poly- 
gonal cells. As the filaments project at right angles to the 
surface of the leaf, they would have been lable to be broken 
whenever the lobes closed together, had it not been for the 
articulation which allows them to bend flat down. 
These filaments, from their tips to their bases,f are ex- 
quisitely sensitive to a momentary touch. It is scarcely 
possible to touch them ever so lightly or quickly with any 
hard object without causing the lobes to close. A piece of 
very delicate human hair, 24 inches in length, held dangling 
over a filament, and swayed to and fro so as to touch it, did 
not excite any movement. But when a rather thick cotton 
thread of the same length was similarly swayed, the lobes 
closed. Pinches of fine wheaten flour, dropped from a height, 
produced no effect. The above-mentioned hair was then fixed 
into a handle, and cut off so that 1 inch projected; this 
* [These hairs were absent in the 
specimens examined by Kurtz (Reich- 
ert and Du Bois-Reymond’s ‘ Archiv.’ 
1876).—F. D.] 
+ [Both Fraustadt and De Candolle 
have described the structure of these 
tilaments, and have shown that their 
morphological rank is that of “ emer- 
gencies.””—F. D.] 
t [Batalin (‘ Flora,’ 1877) quotes 
Oudemans (R. Academy of Sciences of 
Amsterdam, 1859), to the effect that 
the filaments are much more sensitive 
at the base than elsewhere. Batalin 
confirms the fact from his own obser- 
vations.—F, D.] 
