1 82 COMPARATIVE ELECTRO-PHYSIOLOGY 



the electrical responses undergo an almost complete aboli- 

 tion. During a certain week, for instance, the temperature 

 was 10 C, and the electrical responses then obtained from 

 radish (Raphanus sativus) were considerable, giving an E.M. 

 response which varied from '05 to *i volt. Two or three 

 days afterwards, however, as the effect of frost, I found the 

 electrical response of this plant to have practically dis- 

 appeared. A few specimens were found nevertheless which 

 were somewhat resistant. But even in these the average 

 E.M. response had only a value of '003 volt, instead of the 

 normal mean of '075 volt. That is to say, their average 

 sensitiveness had been reduced to one twenty-fifth. On now 



FIG. 121. Photographic Record of Pulsations of Desmodium during 

 Continuous Rise of Temperature from 30 C. to 39 C. 



warming these radishes to 20 C. there was an appreciable 

 revival, as shown by their increasing response. But in those 

 specimens which had been frost-bitten, warming effected no 

 restoration. From this it would appear that frost killed some, 

 which could not be subsequently revived, whereas others 

 were reduced to a condition of torpidity from which, on 

 warming, there was a revival. 



I have also investigated the effect of an artificial lowering 

 of temperature on the electrical response of plants. The 

 Eucharis lily is particularly sensitive to cold. In this case I 

 took the petiole, and obtained response at the ordinary 

 temperature of the room, which was at the time 17 C. I 

 then placed it for 15 minutes in a cooling chamber at a 



