INORGANIC RESPONSE 129 



also. It would appear, then, that in all the phenomena 

 which we have studied under the heads of ' stair- 

 case ' effect, increase of response after continuous sti- 

 mulation, and fatigue, there is a similarity between the 

 observations made upon the response of muscle and 

 nerve on the one hand, and that of metals on the other. 

 Even in their abnormalities we have seen an agreement. 



But amongst these phenomena themselves, though 

 at first sight so diverse, there is some kind of continuity. 

 Calling all normal response positive, for the sake of 

 convenience, we observe its gradual modification, 

 corresponding to changes in the molecular condition of 

 the substance. 



Beginning with that case in which molecular modi- 

 fication is extreme, we find a maximum variation of 

 response from the normal, that is to say, to negative. 



Continued stimulation, however, brings back the 

 molecular condition to normal, as evidenced by the pro- 

 gressive lessening of the negative response, culminating 

 in reversion to the normal positive. This is equally 

 true of nerve and metal. 



In the next class of phenomena, the modification 

 of molecular condition is not so great. It now exhibits 

 itself merely as a relative inertness, and the responses, 

 though positive, are feeble. Under continued stimula- 

 tion, they increase in the same direction as in the last 

 case, that is to say, from less positive to more positive, 

 being the reverse of fatigue. This is evidenced alike 

 by the staircase effect and by the increase of response 

 after tetanisation, seen not only in nerve but also in 

 platinum and tin. 



K 



