334 RESEARCHES ON IRRITABILITY OF PLANTS 



this I may mention dilute sugar solution. The specimen 

 experimented on was but moderately vigorous. After 

 taking four normal pulsations, which are seen to be uniform 

 (fig. 176), a 2 per cent, solution of sugar was applied inter- 

 nally at the moment marked by an arrow. No immediate 

 effect was noticeable, but after an interval of a single 



Fig. 178.- 



-Effect of internal application of 15 per cent, solution 

 of alcohol. 



Fig. 179. — Effect of dilute carbonic-acid gas ; enhancement of 

 amplitude and slowing of the period. 



pulsation the stimulating character of the agent became 

 evident by the resulting staircase enhancement of pulsation. 



Effect of Alcohol 



The effect of this reagent in dilute solutions is in general 

 to induce an enhancement of response. Stronger solu- 

 tion, however, induces a depression which may culminate 



