ELECTRIC RESPONSE IN PLANTS 31 



culminating in death, soon became, visually evident. 

 The leaves began to droop, a peculiar death-discoloura- 

 tion began to spread from the mid rib along the 

 venation of the leaves. Another peculiarity was also 

 observed. The aphides feeding "on the leaves died even 

 before the appearance of the discoloured patches, 

 whereas on the leaves of the stalks placed in water 

 these little creatures maintained their accustomed acti- 

 vity, nor did any discolouration occur. In order to 

 study the effect of poison, another set was placed in 

 water containing a small quantity of mercuric chloride. 

 The leaves here underwent the same change of appear- 

 ance, and the aphides met with the same untimely fate, 

 as in the case of those subjected to the action of 

 chloroform. There was hardly any visible change in 

 the appearance of the stalks themselves, which were to 

 all outer seeming as living as ever, indications of death 

 being apparent only on the leaf surfaces. I give below 

 the results of several sets of experiments, from which it 

 would appear that whereas there was strong normal 

 response in the group of stalks kept in water, there was 

 practically a total abolition of all response in those 

 anaesthetised or poisoned. 



Experiments on the effect of anaesthetics and poisons. 

 A batch of ten leaf-stalks of plane-tree was placed with 

 the cut ends in water, and leaves in air ; an equal 

 number was immersed in chloroform- water ; a third batch 

 was placed in 5 per cent, solution of mercuric chloride. 



Similarly a batch of three horse-chestnut leaf-stalks 

 was put in water, another batch in chloroform-water, 

 and a third batch in mercuric chloride solution. 



