Propionic Acid.—­Three leaves were immersed in ninety minims of a mixture of one part to 437 of water; in 1 hr. 50 m. there was no inflection; but after 3 hrs. 40 m. one leaf was greatly inflected, and the other two slightly.  The inflection continued to increase, so that in 8 hrs. all three leaves were closely inflected.  Next morning, after 20 hrs., most of the glands were very pale, but some few were almost black.  No mucus had been secreted, and the surrounding fluid was only just perceptibly tinted of a pale pink.  After 46 hrs. the leaves became slightly flaccid and were evidently killed, as was afterwards proved to be the case by keeping them in water.  The protoplasm in the closely inflected tentacles was not in the least aggregated, but towards their bases it was collected in little brownish masses at the bottoms of the cells.  This protoplasm was dead, for on leaving the leaf in a solution of carbonate of ammonia, no aggregation ensued.  Propionic acid is highly poisonous to Drosera, like its ally acetic acid, but induces inflection at a much slower rate.

Oleic Acid (given me by Prof.  Frankland).—­Three leaves were immersed in this acid; some inflection was almost immediately caused, which increased slightly, but then ceased, and the leaves seemed killed.  Next morning they were rather shrivelled, and many of the glands had fallen off the tentacles.  Drops of this acid were placed on the discs of four leaves; in 40 m. all the tentacles were greatly inflected, excepting the extreme marginal ones; and many of these after 3 hrs. became inflected.  I was led to try this acid from supposing that it was present (which does not seem to be the case)* in olive oil, the action of which is anomalous.  Thus drops of this oil placed on the disc do not cause the outer tentacles to be inflected; yet when minute drops were added to the secretion surrounding the glands of the outer tentacles, these were occasionally, but by no means always, inflected.  Two leaves were also immersed in this oil, and there

* See articles on Glycerine and Oleic Acid in Watts’ ’Dict. of Chemistry.’ [page 193]

was no inflection for about 12 hrs.; but after 23 hrs. almost all the tentacles were inflected.  Three leaves were likewise immersed in unboiled linseed oil, and soon became somewhat, and in 3 hrs. greatly, inflected.  After 1 hr. the secretion round the glands was coloured pink.  I infer from this latter fact that the power of linseed oil to cause inflection cannot be attributed to the albumin which it is said to contain.

Carbolic Acid.—­Two leaves were immersed in sixty minims of a solution of 1 gr. to 437 of water; in 7 hrs. one was slightly, and in 24 hrs. both were closely, inflected, with a surprising amount of mucus secreted.  These leaves were washed and left for two days in water; they remained inflected; most of their glands became pale, and they seemed dead.  This acid is poisonous, but does not act nearly so