624 Professor Jagadis Chunder Bose [May 10, 



test is supposed to lie in the modification of response uuder anesthe- 

 tics or poisons, when " that which is physiological, i.e. dependent on 

 the physico-chemical conditions peculiar to the living state, will he 

 suppressed ; that which is purely physical will persist." * In order, 

 then, to determine whether response in plants is or is not of a phy- 

 siological character, we may subject them to the action of chloroform. 

 Taking a fresh stalk we get the usual strong response. We now 

 apply chloroform, and find as anaesthetic action proceeds, that the 

 responses wane, and are finally abolished. There are various other 

 poisons which I find to be very effective in killing response. 



5. The physiological nature of the response may be further de- 

 monstrated if we repeat experiment 2, after killing the stalk by brief 

 immersion in hot water. No response current will now be evoked 

 on stimulation of either A or B end. 



As the conditions in 2 and 5 were exactly similar, except for the 

 fact that in the former case the stalk was alive, and in the latter 

 killed, on the method of difference we are justified in concluding that 

 the response was physiological, or characteristic of a living state of 

 matter. 



6. Or we may demonstrate the same fact in a more striking 

 manner by a modification of experiment 2. One half of the stalk, 

 say the B half, is killed, by dipping that half in hot water. On 

 now subjecting the B half to stimulation, there is no response ; but 

 stimulation of the A end gives strong response (6, Fig. 6). 



Nothing has yet been said of the advantage of the 



Universal electrical over the mechanical method of obtaining 



Applicability response. As has been said before, the mechanical 



of the test of method is limited in its application. A nerve, for 



Electric example, does not undergo any change of form 



Mesponse. when excited, and its response cannot therefore 



he detected by this method. But by the electrical 



method we are able to detect, not only the response of muscles, but 



that of all forms of living tissue. 



The intensity of electrical response is also a measure of physio- 

 logical activity. When this physiological activity of the living 

 substance is diminished by anaesthetics, the electrical responses are 

 also correspondingly diminished. And when the living tissue is in 

 any way killed, the electrical response disappears altogether. Hence 

 it is said that " the most general and the most delicate sign of life is 

 the electrical response." f 



Thus, electrical response is regarded as the criterion between the 

 living and non-living. Where it is, life is said to be ; where it is not 

 found, we are in presence of death, or else of that which has never 

 lived : for in this respect there is a great gulf fixed between the 



* "Waller, ' Animal Electricity,' p. 104. 



t " The Electrical Sign of Life. . . . An isolated muscle gives sign of life 

 by contracting when stimulated. . . . An ordinary nerve, normally connected 



