236 DIONAZA MUSCIPULA. (Cuar. XIII. 
sensitive. No doubt, as in the case of Drosera, the plant is 
indifferent to the heaviest shower of rain. Drops ofasolution 
of half an ounce of sugar to a fluid ounce of water were 
repeatedly allowed to fall from a height on the filaments, but 
produced no effect, unless they adhered to them. Again, I 
blew many times through a fine pointed tube with my utmost 
force against the filaments without any effect ; such blowing 
heing received 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 mcderately strong solu- 
tion 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. 10m. 
and three other leaves for some minutes, in water at tem- 
peratures varying between 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being gently withdrawn from the water, closed rather quickly.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 he in good condition, 
as they closed when their filaments were touched. Never- 
theless 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 immer- 
sion 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. 
It 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. 
I am confirmed in this belief by the effects of immersing a 
leaf of Dionea in a moderately strong solution of sugar; the 
leaf having been previously left for 1 hr. 10 m. in water 
without any effect; for now the lobes closed rather quickly, 
