i2 4 RESPONSE IN THE LIVING AND NON-LIVING 



there could be no possibility of the evolution of C0 2 , 

 they tended again to become normal. 



If after mounting a wire in a cell filled with water, 

 it be set aside for too long a time, I have sometimes 

 noticed that it undergoes a certain modification, owing 

 to which its response ceases to be normal and becomes 

 reversed in sign. I have obtained this effect with 

 various metals, for instance lead and tin, and even with 

 the chemically inactive substance platinum. 



FIG. 75. ABNORMAL POSITIVE (UP) KESPONSE IN NERVE CONVERTED INTO 



NORMAL (DOWN) KESPONSE AFTER CONTINUOUS STIMULATION T (WALLER) 



The galvanometer is not dead-beat, and shows after-oscillation. 



The subject will be made clearer if we first follow 

 in detail the phenomenon exhibited by modified nerve, 

 giving this abnormal response. The normal responses 

 in nerve are usually represented by 'down' and the 

 reversed abnormal responses by ' up ' curves. In the 

 modified nerve, then, the abnormal responses are ' up ' 

 instead of the normal 6 down.' The record of such 

 abnormal response in the modified nerve is shown in 

 fig. 75. It will be noticed that in this, the successive 



