182 DROSERA ROTUNDIFOLIA. [Cuar. IX. 
on these leaves were closely clasped over the meat which had been 
carried to their centres; whilst the vertical and sub-vertical tentacles 
on the other leaves to which no meat had been given had fully re- 
expanded. Judging, however, from the subsequent action of a weak 
solution of carbonate of ammonia cn one of these latter leaves, it had 
not perfectly recovered its excitability and power of movement in 22 
hrs.; but another leaf, after an additional 24 hrs., had completely re- 
covered, judging from the manner in which it clasped a fly placed on 
its disc. 
I will give only one other experiment. After the exposure of a 
plant for 2 hrs. to the gas, one of its leaves was immersed in a rather 
strong solution of carbonate of ammonia, together with a fresh leaf 
from another plant. The latter had most of its tentacles strongly 
inflected within 80 m.; whereas the leaf which had been exposed to 
the carbonic acid remained for 24 hrs. in the solution without under- 
going any inflection, with the exception of two tentacles. ‘This leaf 
had been almost completely paralysed, and was not able to recover its 
sensibility whilst still in the solution, which from having been made 
with distilled water probably contained little oxygen. 
Concluding Remarks on the Effects of the foregoing Agents.— 
As the glands, when excited, transmit some influence to the 
surrounding tentacles, causing them to bend and their glands 
to pour forth an increased amount of modified secretion, I 
was anxious to ascertain whether the leaves included any 
element having the nature of nerve-tissue, which, though 
not continuous, served as the channel of transmission. This 
led me to try the several alkaloids and other substances which 
are known to exert a powerful influence on the nervous 
system of animals. I was at first encouraged in my trials 
by finding that strychnine, digitaline, and nicotine, which 
all act on the nervous system, were poisonons to Drosera, and 
caused a certain amount of inflection. Hydrocyanic acid, 
again, which is so deadly a poison to animals, caused rapid 
movement of the tentacles. But as several innocuous acids, 
though much diluted, such as benzoic, acetic, &c., as well as 
some essential oils, are extremely poisonous to Drosera, and 
quickly cause strong inflection, it seems probable that 
strychnine, nicotine, digitaline, and hydrocyanic acid, excite 
inflection by acting on elements in no way analogous to 
the nerve-cells of animals. If elements of this latter nature 
had been present in the leaves, it might have been expected 
that morphia, hyoscyamus, atropine, veratrine, colchicine, 
curare, and diluted alcohol would have produced some marked 
effect; whereas these substances are not poisonous and have 
