274 DllOSEKA ROTUNDIFOLIA. CHAP. XI. 



In Hie ninth chapter the effects of the absorption of 

 various alkaloids and certain other substances were 

 described. Although some of these are poisonous, yet 

 as several, which act powerfully on the nervous system 

 of animals, produce no effect on Drosera, we may infer 

 that the extreme sensibility of the glands, and their 

 power of transmitting 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 immersion in the 

 poison of the cobra-snake does not in the least 

 check, but rather stimulates, the spontaneous move- 

 ments of the protoplasm in the cells of the tentacles. 

 Solutions of various salts and acids behave very dif- 

 ferently in delaying or in quite arresting the sub- 

 sequent action of a solution of phosphate of ammonia. 

 Camphor dissolved in water acts as a stimulant, as 

 do small doses of certain essential oils, for they cause 

 rapid and strong inflection. Alcohol is not a stimu- 

 lant. The vapours of camphor, alcohol, chloroform, 

 sulphuric and nitric ether, are poisonous in moderately 

 large doses, but in small doses serve as narcotics or 

 aneesthetics, greatly delaying the subsequent action 

 of meat. But some of these vapours also act as stimu- 

 lants, exciting rapid, almost spasmodic movements in 

 the tentacles. Carbonic acid is likewise a narcotic, 

 and retards the aggregation of the protoplasm when 

 carbonate of ammonia is subsequently given. The first 

 access of air to plants which have, been immersed in 

 this gas sometimes acts as a stimulant and induces 

 movement. But, as before remarked, a special pharma- 

 copoeia would be necessary to describe the diversified 

 effects of various substances on the leaves of Drosera'. 

 In the tenth chapter it was shown that fhe sensitive- 



