116 DROSERA ROTUNDIFOLIA. [Chap. VII. 



24 hrs. ; but not a single tentacle was inflected. In order 

 to produce this efiFect, the carbonate must be absorbed by 

 the glands. 



The vapour produces a powerful effect on the glands, and 

 induces inflection. Three plants with their roots in bottles, 

 so that the surrounding air could not have become very 

 humid, were placed under a bell-glass (holding 122 fluid 

 ounces), together with 4 grains of carbonate of ammonia in a 

 watch-glass. After an interval of 6 hrs. 15 m. the leaves 

 appeared unaffected; but next morning, after 20 hrs., the 

 blackened glands were secreting copiously, and most of the 

 tentacles were strongly inflected. These plants soon died. 

 Two other plants were placed under the same bell-glass to- 

 gether with half a grain of the carbonate, the air being ren- 

 dered as damp as possible; and in 2 hrs. most of the leaves 

 were affected, many of the glands being blackened and the 

 tentacles inflected. But it is a curious fact that some of the 

 closely adjoining tentacles on the same leaf, both on the 

 disc and round the margins, were much, and some, apparent- 

 ly, not in the least affected. The plants were kept under the 

 bell-glass for 24 hrs., but no further change ensued. One 

 healthy leaf was hardly at all affected, though other leaves on 

 the same plant were much affected. On some leaves all the 

 tentacles on one side, but not those on the opposite side, 

 were inflected. I doubt whether this extremely unequal ac- 

 tion can be explained by supposing that the more active 

 glands absorb all the vapour as quickly as it is generated, 

 so that none is left for the others; for we shall meet with 

 anal(^ous cases with air thoroughly permeated with the 

 vapours of chloroform and ether. 



Minute particles of the carbonate were added to the secre- 

 tion surrounding several glands. These instantly became 

 black and secreted copiously; but, except in two instances, 

 when extremely minute particles were given, there was 

 no inflection. This result is analogous to that which 

 follows from the inunersion of leaves in a strong solution 

 of one part of the carbonate to 109, or 146, or even 218 

 of water, for the leaves are then paralysed and no inflec- 

 tion ensues, though the glands are blackened, and the 

 protoplasm in the cells of the tentacles undergoes strong 

 aggregatioo. 



