ELECTRIC RESPONSE OF ACID PLANTS 125 



which excrete malic and oxalic acids, and have been 

 collected as ' vinegar ' from ancient times in India and used 

 for medicine and diet. 



Records of electric responses of the Cicer are given below 

 which are seen to exhibit very pronounced electro-posi- 

 tivity. The photosynthetic action depends on the effective 

 intensity of light, and it will be shown in a later chapter 



Fig. 35. Electric Response of Cicer arietinum 

 The first record, S, is under direct sunlight ; the second, R, under 

 light transmitted through red glass ; the third, B, under light 

 transmitted through blue glass ; and the fourth, S, once more 

 under direct sunlight. 



that red light is more effective in photosynthesis than blue 

 light. The electric response exhibits corresponding varia- 

 tions. The first large response (fig. 35, S) was given on 

 exposure to strong sunlight. Red glass was now interposed 

 in the path of light, and the response (R) was still of con- 

 siderable amplitude. On the interposition of blue glass 

 the response (B) became extremely feeble. The response 

 taken once more under sunlight exhibited the original 



