fig. 77)
transformed into normal 'up' response, after continuous
stimulation, T.]

On placing the three sets of records--nerve, tin, and platinum--side by
side, it will be seen how essentially similar they are in every
respect.[17]

This reversion to normal is seen to have appeared in a pronounced manner
after rapidly continuous stimulation, in process of which the modified
molecular condition must in some way have reverted to the normal.

[Illustration: FIG. 78.--THE GRADUAL TRANSITION FROM ABNORMAL TO NORMAL
RESPONSE IN PLATINUM
The transition will be seen to have commenced at the third and ended at
the seventh, counting from the left.]

Being desirous to trace this change gradually taking place, I took a
platinum wire cell giving modified responses, and obtained a series of
records of effects of individual stimuli continued for a long time. In
this series, the points of transition from modified response to normal
will be clearly seen (fig. 78).

[Illustration: FIG. 79.--THE NORMAL RESPONSE _a_ IN NERVE ENHANCED TO
_b_ AFTER CONTINUOUS STIMULATION T (WALLER)
The normal response in nerve is recorded 'down.']

[Illustration: FIG. 80.--ENHANCED RESPONSE IN PLATINUM AFTER CONTINUOUS
STIMULATION T]

#Increased response after continuous stimulation.#--We have seen that
responses to uniform stimuli sometimes show a staircase increase,
apparently owing to the gradual removal of molecular sluggishness.
Possibly analogous to this is the increase of response in nerve after
continuous stimulation or tetanisation, observed by Waller (fig. 79).
Like the staircase effect, this contravenes the commonly accepted theory
of the dissimilation of tissue by stimulus, and the consequent
depression of response. It is suggested by Waller that this increase of
response after tetanisation may be due to the hypothetical evolution of
CO_2 to which allusion has previously been made.

[Illustration: FIG. 81.--ENHANCED RESPONSE IN TIN AFTER CONTINUOUS
STIMULATION T]

But there is an exact correspondence between this phenomenon and that
exhibited by metals under similar conditions. I give here two sets of
records (figs. 80, 81), one obtained with platinum and the other with
tin, which demonstrate how the response is enhanced after continuous
stimulation in a manner exactly similar to that noticed in the case of
nerve.

The explanation which has been suggested with regard to the staircase
effect--increased molecu