EFFECT OF TEMPERATURE ON ELECTRICAL RESPONSE l8l 



temperature abolishes the pulsation. In fig. 120 are seen 

 (i) the records of normal pulsations; (2) their arrest under 

 the application of ice-cold water ; and (3) their revival, as 

 the plant regains the temperature of the room. In fig. 121 

 is shown the effect on similar pulsations of a rising tempera- 

 ture. The records in this case were obtained with a different 



FIG. 120. Photographic Record showing Effect of Rapid Cooling, by 

 Ice-cold Water, on Pulsations' of Desmodium gyrans 



Normal pulsations recorded to the left. Effect of application of ice-cold 

 water is seen in the production of diminished amplitude and abolition 

 of pulsation. Gradual return to the temperature of the room revives 

 the pulsation in a staircase manner, the period remaining approximately 

 constant. Note that cooling displaces the pulsation in a downward or 

 contracted direction. Gradual warming, conversely, is seen to produce 

 the opposite displacement towards expansion. Up-records represent 

 the fall of the leaflet, down-records its rise. 



specimen, and it is seen that the pulsations are diminished 

 in amplitude while their period is quickened, with rise of 

 temperature. When the temperature is raised still higher, 

 they come to a stop altogether. 



We shall next proceed to observe the effect of temperature 

 on the electrical response of plants. As regards the influence 

 of cold, for example, I have found, during the course of a 

 research carried out in England, that after frosty weather, 



