Half-minims of a solution of one part to 437 of water were placed on the discs of three leaves and acted most energetically, causing the tentacles of one to be inflected in 15 m., and the blades of all three to be much curved inwards in 2 hrs. 15 m.  Similar drops of a solution of one part to 1312 of water, (1 gr. to 3 oz.) were then placed on the discs of five leaves, so that each received the 1/2880 of a grain (.0225 mg.).  After 8 hrs. the tentacles of four of them were considerably inflected, and after 24 hrs. the blades of three.  After 48 hrs. all five were almost fully re-expanded.  I may mention with respect to one of these leaves, that a drop of water had been left during the previous 24 hrs. on its disc, but produced no effect; and that this was hardly dry when the solution was added.

Similar drops of a solution of one part to 1750 of water (1 gr. to 4 oz.) were next placed on the discs of six leaves; so that each received 1/3840 of a grain (.0169 mg.); after 8 hrs. three of them had many tentacles and their blades inflected; two others had only a few tentacles slightly inflected, and the sixth was not at all affected.  After 24 hrs. most of the leaves had a few more tentacles inflected, but one had begun to re-expand.  We thus see that with the more sensitive leaves the 1/3840 of a grain, absorbed by the central glands, is enough to make many of the exterior tentacles and the blades bend, whereas the 1/1920 of a grain of the carbonate similarly given produced no effect; and 1/2880 of a grain of the nitrate was only just sufficient to produce a well-marked effect.

A minute drop, about equal to 1/20 of a minim, of a solution of one part of the phosphate to 875 of water, was applied to the secretion on three glands, each of which thus received only 1/57600 of a grain (.00112 mg.), and all three tentacles became inflected.  Similar drops of a solution of one part to 1312 of water (1 gr. to 3 oz.) were now tried on three leaves; a drop being applied to four glands on the same leaf.  On the first leaf, three of the tentacles became slightly inflected in 6 m., and re-expanded after 8 hrs. 45 m.  On the second, two tentacles became sub-inflected in 12 m.  And on the third all four tentacles were decidedly inflected in 12 m.; they remained so for 8 hrs. 30 m., but by the next morning were fully re-expanded. [page 156] In this latter case each gland could have received only the 1/115200 (or .000563 mg.) of a grain.  Lastly, similar drops of a solution of one part to 1750 of water (1 gr. to 4 oz.) were tried on five leaves; a drop being applied to four glands on the same leaf.  The tentacles on three of these leaves were not in the least affected; on the fourth leaf, two became inflected; whilst on the fifth, which happened to be a very sensitive one, all four tentacles were plainly inflected in 6 hrs. 15m.; but only one remained inflected after 24 hrs.  I should, however, state that in this case an unusually large drop adhered to the head of the pin.  Each