I shall now give a record which will exhibit an exactly similar transformation from the abnormal to normal response after continuous stimulation. Here the normal responses are represented by 'up' and the abnormal by 'down' curves. This record was given by a tin wire, which had been molecularly modified (fig. 76). We have at first the abnormal responses; successive responses are undergoing a diminution or tending towards the normal; after continuous stimulation (T), the subsequent responses are seen to have become normal. Another record, obtained with platinum, shows the same phenomenon (fig. 77). [Illustration: FIG. 76 AND FIG. 77 Abnormal 'down' response in tin (fig. 76) and in platinum (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]