Although in all the more important experiments the difference between the leaves simultaneously immersed in water and in the several solutions will be described, nevertheless it may be well here to give a summary of the effects of water. The fact, moreover, of pure water acting on the glands deserves in itself some notice. Leaves to the number of 141 were immersed in water at the same time with those in the solutions, and their state recorded at short intervals of time. Thirty-two other leaves were separately observed in water, making altogether 173 experiments. Many scores of leaves were also immersed in water at other times, but no exact record of the effects produced was kept; yet these cursory observations support the conclusions arrived at in this chapter. A few of the long-headed tentacles, namely from one to about six, were commonly inflected within half an hour after immersion; as were occasionally a few, and rarely a considerable number of the exterior round-headed tentacles. After an immersion of from 5 to 8 hrs. the short tentacles surrounding the outer parts of the disc generally become inflected, so that their glands form a small dark ring on the disc; the exterior tentacles not partaking of this movement. Hence, excepting in a few cases hereafter to be specified, we can judge whether a solution produces any effect only by observing the exterior tentacles within the first 3 or 4 hrs. after immersion. Now for a summary of the state of the 173 leaves after an immersion of 3 or 4 hrs. in pure water. One leaf had almost all its tentacles inflected; three leaves had most of them sub-inflected; and thirteen had on an average 36.5 tentacles inflected. Thus seventeen leaves out of the 173 were acted on in a marked manner. Eighteen leaves had from seven to nineteen tentacles inflected, the average being 9.3 tentacles for each leaf. Forty-four leaves had from one to six tentacles inflected, generally the long-headed ones. So that altogether of the 173 leaves carefully observed, seventy-nine were affected by the water in some degree, though commonly to a very slight degree; and ninety-four were not affected in the least degree. This [page 140] amount of inflection is utterly insignificant, as we shall hereafter see, compared with that caused by very weak solutions of several salts of ammonia.