Chap. VIII.] THE EFFECTS OF ACIDS. 157 



few were almost black. No e&ucus had been secreted, and the 

 surrounding lluid 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 base^ it was collected in 

 little brownish masses at the bottoms of the cells. This proto- 

 plasm was dead, for, on leaving the leaf in a solution of carbonate 

 of ammonia, no aggregation ensued. Propionic acid is highly poi- 

 sonous 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 olT 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 ease)- 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 secre- 

 tion surrounding the glands of the outer tentacles, these were oc- 

 casionally, but by no means always, inflected. Two leaves were 

 also immersed in this oil, and there 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 can- 

 not 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 rtmained inflected; most of their glands be- 

 came pale, and they seemed dead. This acid is poisonous, but does 

 not act nearly so rapidly or powerfully as might have been ex- 

 pected from its known destructive power on the lowest organisms. 

 Half-minims of the same solution were placed on the discs of three 

 leaves; after 24 hrs. no inflection of the outer tentacles ensued, and 

 when bits of meat were given them they became fairly well in- 

 flected. Again half-minims of a stronger solution, of one part to 

 218 of water, were placed on the discs of three leaves; no inflection 

 of the outer tentacles ensued ; bits of meat were then given as be- 

 fore; one leaf alone became well inflected, the discal glands of the 

 other two appearing much injure<i and dry. We thus see that 

 the glands of the discs, after absorbing this acid, rarely transmit 



See articles on Glycerine and Oleic Acid in Watts' ' Diet, of Cltcm- 

 Istry.' 



