Potassium, Citrate of.—­Half-minims of a solution of one part to 437 of water, left on the discs of six leaves for three days, and the immersion of three leaves for 9 hrs., each in 30 minims of a solution of one part to 875 of water, did not produce the least effect.

Potassium, Oxalate of.—­Half-minims were placed on different occasions on the discs of seventeen leaves; and the results perplexed me much, as they still do.  Inflection supervened very slowly.  After 24 hrs. four leaves out of the seventeen were well inflected, together with the blades of two; six were slightly affected, and seven not at all.  Three leaves of one lot were observed for five days, and all died; but in another lot of six, all excepting one looked healthy after four days.  Three leaves were immersed during 9 hrs., each in 30 minims of a solution of one part to 875 of water, and were not in the least affected; but they ought to have been observed for a longer time.

Potassium, Chloride of.  Neither half-minims of a solution of one part to 437 of water; left on the discs of six leaves for three days, nor the immersion of three leaves during 25 hrs., in 30 minims of a solution of one part to 875 of water, produced the least effect.  The immersed leaves were then treated with carbonate of ammonia, as described under nitrate of potash, and with the same result.

Potassium, Iodide of.—­Half-minims of a solution of one part to 437 of water were placed on the discs of seven leaves.  In 30 m. one leaf had the blade inflected; after some hours three leaves had most of their submarginal tentacles moderately inflected; the remaining three being very slightly affected.  Hardly any of these leaves had their outer tentacles inflected.  After 21 hrs. all re-expanded, excepting two which still had a few submarginal tentacles inflected.  Three leaves were next [page 181] immersed for 8 hrs. 40 m., each in 30 minims of a solution of one part to 875 of water, and were not in the least affected.  I do not know what to conclude from this conflicting evidence; but it is clear that the iodide of potassium does not generally produce any marked effect.

Potassium, Bromide of.—­Half-minims of a solution of one part to 437 of water were placed on the discs of six leaves; after 22 hrs. one had its blade and many tentacles inflected, but I suspect that an insect might have alighted on it and then escaped; the five other leaves were in no way affected.  I tested three of these leaves with bits of meat, and after 24 hrs. they became splendidly inflected.  Three leaves were also immersed for 21 hrs. in 30 minims of a solution of one part to 875 of water; but they were not at all affected, excepting that the glands looked rather pale.

Lithium, Acetate of.—­Four leaves were immersed together in a vessel containing 120 minims of a solution of one part to 437 of water; so that each received, if the leaves absorbed equally, 1/16 of a grain.  After 24 hrs. there was no inflection.  I then added, for the sake of testing the leaves, some strong solution (viz. 1 gr. to 20 oz., or one part to 8750 of water) of phosphate of ammonia, and all four became in 30 m. closely inflected.