104 RESEARCHES ON IRRITABILITY OF PLANTS 



In order to discover how constant is the death-point, I 

 repeated the experiment with numerous other specimens. 

 We have seen that the pulvinated organs present in the 

 leaves of Desmodium gyrans and the bean plant (Vicia 

 Faba) exhibit responsive movement under excitation. In 

 fig. 60 is depicted the death record taken under standard 

 conditions with the leaf of Desmodium. The record was 

 commenced at 35° C. ; it is seen that thermo-mechanical 

 inversion took place at 61° C. 



Fig. 60. — Record showing death-point of Desmodium 

 at 61° C. 



The next figure (fig. 61) shows the record with the leaf 

 of bean plant. Here the responsive movements are very 

 large. The inversion is seen to take place at 60° C. 



The occurrence of death-spasm may also be shown by 

 means of ordinary plants. If we take a hollow tubular 

 organ, such as the hollow leaf-stalk of gourd or hollow 

 flower-stalk of any other plant, cut it in the form of a 

 spiral and subject it to the rising temperature of the bath, 

 there is noticed at first an expansive movement of uncurhng 

 of spiral. On reaching the death-point, however, the former 

 movement is suddenly reversed to one of curling. 



Flowers like French marigold exhibit death-spasm by 

 sudden movement of opening or closure. 



By employing the electric mode of investigation I 



