324 



PLANT RESPONSE 



minutes after the first introduction of ether into the 

 plant chamber. On blowing off the ether-vapour, there 



was in this case no revival 

 of response. In those cases, 

 however, in which the ether- 

 vapour is more diluted with 

 air, or applied for a shorter 

 period, the depression is 

 temporary only, and is fol- 

 lowed by revival. But if 

 a larger quantity of ether- 

 vapour be at once introduced, 

 a permanent arrest, in the 

 relaxed position, quickly en- 

 sues. Before this happens, 

 there may be one or two 

 spasmodic flutterings, but 

 these quickly subside, as will 

 be seen in the photographic 

 record given (fig. 130). 

 Effect of alcohol. — The effect of this reagent is much 

 modified by the tonic condition of the specimen. For 

 example, in the case of a weaklier plant, the application, 

 even of dilute solutions, induces rapid diminution and arrest 

 of pulsation. More vigorous specimens can, however, with- 

 stand the deleterious effect of this drug, and bear stronger 

 doses. In the photographic record here given (fig. 131) a 

 5 per cent, solution is seen to induce a greater regularity 

 and amplitude of pulsation. The subsequent application of a 

 10 per cent, solution causes a moderate, and 1 5 per cent, a still 

 greater, depression. The application of a 5 per cent, solution 

 to a weakly specimen, however, is found, as said before, to 

 induce a depression so great as to cause a speedy arrest. 



Effect of carbonic acid. — The first effect of the intro- 

 duction of this gas is sometimes one of exaltation. This is 

 however, brief, and is followed by depression and sudden 

 permanent arrest of pulsation in weaklier specimens. In 



Fig. 130. Photographic Record of 

 Effect of Ether Vapour, Large Dose 



Arrow marks moment of application. 

 Pulsation arrested in up, or relaxed, 

 position. It has to be remembered 

 that the up movement of the record 

 corresponds to a down movement 

 of the leaf. 



