258 DIONZZA MUSCIPULA. [Cuar. XIU. 
One lobe can re-expand by itself, as occurred with the torpid 
leaf of which one lobe alone had closed. We have also seen in 
the experiments with cheese and albumen that the two ends of 
the same lobe can re-expand to a certain extent independently 
of each other. But in all ordinary cases both lobes open 
at the same time. The re-expansion is not determined by 
the sensitive filaments; all three filaments on one lobe were 
cut off close to their bases ; and the three leaves thus treated 
re-expanded,—one to a partial extent in 24 hrs.,—a second to 
the same extent in 48 hrs.,—and the third, which had been 
previously injured, not until the sixth day. These leaves 
after their re-expansion closed quickly when the filaments on 
the other lobe were irritated. These were then cut off one 
of the leaves, so that none were left. This mutilated leaf, 
notwithstanding the loss of all its filaments, re-expanded in 
two days in the usual manner. When the filaments have 
been excited by immersion in a solution of sugar, the lobes 
do not expand so soon as when the filaments have been 
merely touched; and this, I presume, is due to their having 
been strongly affected through exosmose, so that they con- 
tinue for some time to transmit a motor impulse to the upper 
surface of the leaf. 
The following facts make me believe that the several 
layers of cells forming the lower surface of the leaf are 
always in a state of tension; and that it is owing to this 
mechanical state, aided probably by fresh fluid being 
attracted into the cells, that the lobes begin to separate or 
expand as soon as the contraction of the upper surface 
diminishes. A leaf was cut off and suddenly plunged 
perpendicularly into boiling water: I expected that the 
lobes would have closed, but instead of doing so, they 
diverged a little. I then took another fine leaf, with the 
lobes standing at an angle of nearly 80° to each other; and 
on immersing it as before, the angle suddenly increased to 
90°. A third leaf was torpid from having recently re- 
Plants, p. 277 (note), says that, 
whilst collecting this plant in its 
native home, “I had occasion to ob- 
serve that a detached leaf would 
make repeated efforts towards dis- 
losing itself to the influence of the 
sun; these attempts consisted in an 
undulatory motion ef the marginal 
cilia, accompanied by a partial open- 
ing and succeeding collapse of the 
lamina, which at length terminated 
in a complete expansion and in the 
destruction of sensibility.” I am 
indebted to Prof. Oliver for this 
reference; but I do not understand 
what took place. 
