222 DROSERA ROTUNDIFOLIA. [Chap. XI. 



animals or to Drosera, and induces only a moderate amount 

 of inflection. Many acids excite the glands to secrete an 

 extraordinary quantity of mucus; and the protoplasm with- 

 in their cells seems to be often killed, as may be inferred 

 from the surrounding fluid soon becoming pink. It is 

 strange that allied acids act very differently: formic acid 

 induces very slight inflection, and is not poisonous; where- 

 as acetic acid of the same strength acts most powerfully and 

 is poisonous. Lactic acid is also poisonous, but causes in- 

 flection only after a considerable lapse of time. Malic acid 

 acts slightly, whereas citric and tartaric acids produce no 

 effect. 



In the ninth chapter the effects of the absorption of 

 various alkaloids and certain other substances were de- 

 scribed. Although some of these are poisonous, yet as 

 several, which act powerfully on the nervous system of ani- 

 mals, produce no effect on Drosera, we may infer that the 

 extreme sensibility of the glands, and their power of trans- 

 mitting an influence to other parts of the leaf, causing 

 movement, or modified secretion, or aggregation, does not 

 depend on the presence of a diffused element, allied to nerve- 

 tissue. One of the most remarkable facts is that long im- 

 mersion in the poison of the cobra-snake does not in the 

 least check, but rather stimulates, the spontaneous move- 

 ment of the protoplasm in the cells of the tentacles. Solu- 

 tions of various salts and acids behave very differently in 

 delaying or in quite arresting the subsequent action of a 

 solution of phosphate of ammonia. Camphor dissolved in 

 water acts as a stimulant, as do small doses of certain essen- 

 tial oils, for they cause rapid and strong inflection. Alcohol 

 is not a stimulant. The vapours of camphor, alcohol, chloro- 

 form, sulphuric and nitric ether, are poisonous in moder- 

 ately large doses, but in small doses serve as narcotics or 

 anaesthetics, greatly delaying the subsequent action of 

 meat. But some of these vapours also act as stimulants, ex- 

 citing rapid, almost spasmodic movements in the tentacles. 

 Carbonic acid is likewise a narcotic, and retards the aggre- 

 gation of the protoplasm when carbonate of ammonia is sub- 

 sequently given. The first access of air to plants which 

 have been immersed in this gas sometimes acts as a stimu- 

 lant and induces movement. But, as before remarked, a 



