C5HAP. VIII.] THE EFFECTS OP ACIDS. 159 



a solution of 1 gr. to 437 of water; after 2 hrs. 10 m, there was 

 much inflection; glands pale; the surrounding fluid of a dark pink 

 colour; after 8 hrs. successive inflection. The leaves were then 

 placed in water; after about 16 hrs. the tentacles were of a very 

 dark red colour, like those of the leaves in acetic acid. After 24 ad- 

 ditional hours, the three leaves were dead and their glands col- 

 ourless. 



Benzoic Acid. Five leaves were immersed, each in thirty min- 

 ims of a solution of 1 gr. to 437 of water. This solution was so 

 weak that it only just tasted acid, yet, as we shall see, was highly 

 poisonous to Drosera. After 52 m. the submarginal tentacles were 

 somewhat inflected, and all the glands very pale-coloured; the sur- 

 rounding fluid was coloured pink. On one occasion the fluid be- 

 came pink in the course of only 12 m. and the glands as white as 

 if the leaf had been dipped in boiling water. After 4 hrs. much 

 inflection; but none of the tentacles were closely inflected, owing, 

 as I believe, to their having been paralysed before they had time to 

 complete their movement. An extraordinary quantity of mucus 

 was secreted. Some of the leaves were left in the solution; others, 

 after an immersion of 6 hrs. 30 m., were placed in water. Next 

 morning both lots were quite dead; the leaves in the solution be- 

 ing flaccid, those in the water (now coloured yellow) of a pale 

 brown tint, and their glands white. 



Succinic Acid. Three leaves were immersed in ninety minims 

 of a solution of one gr. to 437 of water; after 4 hrs. 15 m. con- 

 siderable, and after 23 hrs. great, inflection; many of the glands 

 pale; fluid coloured pink. The leaves were then washed and 

 placed in water; after two days there was some re-expansion, but 

 many of the glands were still white. This acid is not nearly so 

 poisonous as oxalic or benzoic. 



Ui'ic Acid. Three leaves were immersed in 180 minims of a 

 solution of 1 gr. to 875 of warm water, but all the acid was not 

 dissolved; so that each received nearly ^^g of a grain. After 25 m. 

 there was some slight inflection; but this never increased; iifter 



hrs. the glands were not discoloured, nor was the solution col- 

 oured pink ; nevertlicless, much mucus was secreted. The leaves 

 were then placed in water, and by next morning fully re-expanded. 



1 doubt whether this acid really causes inflection, for the slight 

 movement which at first occurred may have been due to the pres- 

 ence of a trace of albuminous matter. But it produces some effect, 

 as shown by the secretion of so much mucus. 



nippvric Acid. Four leaves were immersed in 120 minims of a 

 solution of 1 gr. to 437 of water. After 2 hrs. the fluid was col- 

 oured pink; glands pale, but no inflection. After 6 hrs. some in- 

 flection; after 9 hrs. all four leaves greatly inflected; much mucus 

 secreted; all the glands very pale. The leaves were then left in 

 water for two days; they remained closely inflected, with their 

 glands colourless, and I do not doubt were killed. 



Hydrocyanic Acid. Four leaves were immersed, each in thirty 

 minims of one part to 437 of water; in 2 hrs. 45 m. all the tentacles 

 were considerably inflected, with many of the glands pale; after 



