194 DROSERA ROTUNDIFOLIA. CHAP. \'IIL 



there was no inflection; after 7 hrs. 30 m. two of the leaves 

 showed some inflection, and the glands were almost white; 

 after 21 hrs. two of the leaves were considerably inflected, 

 and a third slightly ; most of the glands were white, the others 

 dark red. After 45 hrs. one leaf had almost every tentacle in- 

 flected ; a second a large number ; the third and fourth very few ; 

 almost all the glands were white, excepting those on the discs of 

 two of the leaves, and many of these were very dark red. The 

 leaves appeared dead. Hence lactic acid acts in a very peculiar 

 manner, causing inflection at an extraordinarily slow rate, and 

 being highly poisonous. Immersion in even weaker solutions, 

 viz. of one part to 1312 and 1750 of water, apparently killed the 

 leaves (the tentacles after a time being bowed backwards), and 

 rendered the glands white, but caused no inflection. 



Gallic, Tannic, Tartaric, and Citric Acids. One part to 437 of 

 water. Three or four leaves were immersed, each in thirty 

 minims of these four solutions, so that each leaf received -^ of a 

 grain, or 4'048 mg. No inflection was caused in 24 hrs.,andtho 

 leaves did not appear at all injured. Those which had been in 

 the tanuic and tartaric acids were placed in a solution (1 gr. to 

 20 oz.) of phosphate of ammonia, but no inflection ensued in 

 24 hrs. On the other hand, the four leaves which had been in 

 the citric acid, when treated with the phosphate, became decidedly 

 inflected in 50 m. and strongly inflected after 5 hrs., and so 

 remained for the next 24 hrs. 



Malic Acid. Three leaves were immersed in ninety minims of 

 a solution of one partjto 437 of water; no inflection was caused 

 in 8 hrs. 20 m., but after 24 hrs. two of them were considerably, 

 and the third slightly, inflected more so than could be ac- 

 counted for by the action of water. No great amount of mucus 

 was secreted. They were then placed in water, and after two 

 days partially re-expanded. Hence this acid is not poisonous. 



Oxalic Acid. Three leaves were immersed in ninety minims of 

 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. excessive 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 additional hours, the three leaves were dead and their 

 glands colourless. 



Benzoic Acid. Five leaves were immersed, each in thirty 

 minims 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 



