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 al/ 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- 
eressive lessening of the negative response, culminating 
im 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 
