Page:Insectivorous Plants, Darwin, 1899.djvu/79

 into quick movement, but does not kill the leaves, as shown either by their subsequent re-expansion or by the aggregation of the protoplasm. We shall now see that a temperature of 130° (54°.4 Cent.) is too high to cause immediate inflection, yet does not kill the leaves. Experiment 1.—A leaf was plunged, and as in all cases waved about for a few minutes, in water at 130° (54°.4 Cent.), but there was no trace of inflection; it was then placed in cold water, and after an interval of 15 m. very slow movement was distinctly seen in a small mass of protoplasm in one of the cells of a tentacle. After a few hours all the tentacles and the blade became inflected.

Experiment 2.—Another leaf was plunged into water at 130° to 131", and, as before, there was no inflection. After being kept in cold water for an hour, it was placed in the strong solution of ammonia, and in the course of 55 m. the tentacles were considerably inflected. The glands, which before had been rendered of a brighter red, were now blackened. The protoplasm in the cells of the tentacles was distinctly aggregated; but the spheres were much smaller than those usually generated in unheated leaves when subjected to carbonate of ammonia. After an additional 2 hrs. all the tentacles, excepting six or seven, were closely inflected.

Experiment 3.—A similar experiment to the last, with exactly the same results.

Experiment 4.—A fine leaf was placed in water at 100 (37.7 Cent.), which was then raised to 145° (62.7 Cent.). Soon after immersion, there was, as might have been expected, strong inflection. The leaf was now removed and left in cold water: but from having been exposed to so high a temperature, it never re-expanded.

Experiment 5.—Leaf immersed at 130° (54°.4 Cent.), and the water raised to 145° (62°.7 Cent.), there was no immediate inflection; it was then placed in cold water, and after 1 hr. 20 m. some of the tentacles on one side became inflected. This leaf was now placed in the strong solution, and in 40 m. all the submarginal tentacles were well inflected, and the glands blackened. After an additional interval of 2 hrs. 45 m. all the tentacles, except eight or ten, were closely inflected, with their cells exhibiting a slight degree of aggregation; but the spheres of protoplasm were very small, and the cells of the exterior tentacles contained some pulpy or disintegrated brownish matter.

Experiments 6 and 7.—Two leaves were plunged in water at 135° (57°.2 Cent.) which was raised to 145° (62°.7 Cent.); neither became inflected. One of these, however, after having been left for 31 m. in cold water, exhibited some slight inflection, which increased after an additional interval of 1 hr. 45 m., until all the tentacles, ex-