292 DIONZA MUSCIPULA. Cuapv. XIII. 
with as much indifference as no doubt is a heavy gale 
of wind. We thus see that the sensitiveness of the 
filaments is of a specialised nature, being related to a 
momentary touch rather than to prolonged pressure ; 
and the touch must not be from fluids, such as air or 
water, but from some solid object. 
Although drops of water and of a moderately strong 
solution of sugar, falling on the filaments, does not 
excite them, yet the immersion of a leaf in pure water 
sometimes caused the lobes to close. One leaf was left 
immersed for 1 hr. 10 m., and three other leaves for 
some minutes, in water at temperatures varying be- 
tween 59° and 65° (15° to 18°3 Cent.) without any 
effect. One, however, of these four leaves, on being 
gently withdrawn from the water, closed rather 
quickly. The three other leaves were proved to be in 
good condition, as they closed when their filaments 
were touched. Nevertheless two fresh leaves on being 
dipped into water at 75° and 624° (23°8 and 16°9 
Cent.) instantly closed. These were then placed with 
their footstalks in water, and after 23 hrs. partially 
re-expanded; on touching their filaments one of 
them closed. This latter leaf after an additional 
24 hrs. again re-expanded, and now, on the filaments 
of both leaves being touched, both closed. We thus 
see that a short immersion in water does not at all 
injure the leaves, but sometimes excites the lobes 
to close. The movement in the above cases was 
evidently not caused by the temperature of the water. 
Tt has been shown that long immersion causes the 
purple fluid within the cells of the sensitive filaments 
to become aggregated ; and the tentacles of Drosera 
are acted on in the same manner by long immersion, 
often being somewhat inflected. In both cases the 
result is probably due to a slight degree of exosmose. 
