Sodium, Nitrate of (pure).—­Half-minims of a solution of one part to 437 of water, containing 1/960 of a grain (.0675 mg.), were placed on the discs of five leaves.  After 1 hr. 25 m. the tentacles of nearly all, and the blade of one, were somewhat inflected.  The inflection continued to increase, and in 21 hrs. 15 m. the tentacles and the blades of four of them were greatly affected, and the blade of the fifth to a slight extent.  After an additional 24 hrs. the four leaves still remained closely inflected, whilst the fifth was beginning to expand.  Four days after the solution had been applied, two of the leaves had quite, and one had partially, re-expanded; whilst the remaining two remained closely inflected and appeared injured.

Three leaves were immersed, each in thirty minims of a solution of one part to 875 of water; in 1 hr. there was great inflection, and after 8 hrs. 15 m. every tentacle and the blades of all three were most strongly inflected.

Sodium, Sulphate of.—­Half-minims of a solution of one part to 437 of water were placed on the discs of six leaves.  After 5 hrs. 30 m. the tentacles of three of them, (with the blade of one) were considerably; and those of the other three slightly, inflected.  After 21 hrs. the inflection had a little decreased, [page 177] and in 45 hrs. the leaves were fully expanded, appearing quite healthy.

Three leaves were immersed, each in thirty minims of a solution of one part of the sulphate to 875 of water; after 1 hr. 30 m. there was some inflection, which increased so much that in 8 hrs. 10 m. all the tentacles and the blades of all three leaves were closely inflected.

Sodium, Phosphate of.—­Half-minims of a solution of one part to 437 of water were placed on the discs of six leaves.  The solution acted with extraordinary rapidity, for in 8 m. the outer tentacles on several of the leaves were much incurved.  After 6 hrs. the tentacles of all six leaves, and the blades of two, were closely inflected.  This state of things continued for 24 hrs., excepting that the blade of a third leaf became incurved.  After 48 hrs. all the leaves re-expanded.  It is clear that 1/960 of a grain of phosphate of soda has great power in causing inflection.

Sodium, Citrate of.—­Half-minims of a solution of one part to 437 of water were placed on the discs of six leaves, but these were not observed until 22 hrs. had elapsed.  The sub-marginal tentacles of five of them, and the blades of four, were then found inflected; but the outer rows of tentacles were not affected.  One leaf, which appeared older than the others, was very little affected in any way.  After 46 hrs. four of the leaves were almost re-expanded, including their blades.  Three leaves were also immersed, each in thirty minims of a solution of one part of the citrate to 875 of water; they were much acted on in 25 m.; and after 6 hrs. 35 m. almost all the tentacles, including those of the outer rows, were inflected, but not the blades.