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 between 59o and 65o (15o to 18o.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  One, however, of these four leaves, on being gently withdrawn from the water, closed rather quickly.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 75o and 62 1/2o (23o.8 and 16o.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.  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. [page 293]

I am confirmed in this belief by the effects of immersing a leaf of Dionaea 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, the tips of the marginal spikes crossing in 2 m. 30 s., and the leaf being completely shut in 3 m.  Three leaves were then immersed in a solution of half an ounce of sugar to a fluid ounce of water, and all three leaves closed quickly.  As I was doubtful whether this was due to the cells on the upper surface of the lobes, or to the sensitive filaments, being acted on by exosmose, one leaf was first tried by pouring a little of the same solution in the furrow between the lobes over the midrib, which is the chief seat of movement.  It was left there for some time, but no movement ensued.  The whole upper surface of leaf was then painted (except close round the bases of the sensitive filaments, which I could not do without risk of touching them) with the same solution, but no effect was produced.  So that the cells on the upper surface are not thus affected.  But when, after many trials, I succeeded in getting a drop of the solution to cling to one of the filaments, the leaf quickly closed.  Hence we may, I think, conclude that the solution causes fluid to pass out of the delicate cells of the filaments by exosmose; and that this sets up some molecular change in their contents, analogous to that which must be produced by a touch.