Chap. IX.] CARBONIC ACID. 181 



The following singular phenomenon sometimes, but by no 

 means always, occurred. A plant was immersed for 2 hrs., and 

 bits of meat were then placed on several glands. In the course of 

 13 m. all the submarginal tentacles on one leaf became considerably 

 inflected ; those with the 'meat not in the least degree more than 

 the othera On a second leaf, which was rather old, the tentacles 

 with meat, as well as a few others, were moderately inflected. 

 On a third leaf all the tentacles were closely inflected, though meat 

 had not been placed on any of the glands. This movement, I pre- 

 sume, may be attributed to excitement from the absorption of oxy 

 gen. The last-mentioned leaf, to which no meat had been given, 

 was fully re-expanded after 24 hrs.; whereas the two other leaves 

 had all their tentacles closely inflected over the bits of meat which 

 by this time had been carried to their centres. Thus these three 

 leaves had perfectly recovered from the effects of the gas in the 

 course of 24 hrs. 



On another occasion some fine plants, after having been left for 

 2 hrs. in the gas, were immediately given bits of meat in the usual 

 manner, and on their exposure to the air most of their tentacles 

 became in 12 m. curved into a vertical or sub-vertical position, but 

 in an extremely irregular manner; some only on one side of the 

 leaf and some on the other. They remained in this position for 

 some time; the tentacles with the bits of meat not having at first 

 moved more quickly or farther inwards than the others without 

 meat. But after 2 hrs. 20 m. the former began to move, and stead- 

 ily went on bending until they reached the centre. Next morning, 

 after 22 hrs., all the tentacles 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 am- 

 monia on 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 recovered, judging 

 from the manner in which it clasped a fly placed in 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 30 m.; whereas the leaf which had been 

 exposed to the carbonic acid remained for 24 hrs. in the solution 

 without undergoing any inflection, with the exception of two ten- 

 tacles. 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 in- 

 fluence to the surrounding tentacles, causing them to bend 



