THE MOLECULAR THEORY OF EXCITATION 



595 



in magnetic responses, similar to those obtained in living 

 tissues. In the next figure (fig. 364) is shown the effect of 

 strong stimulation, which gives rise to responses, not only 

 of greater amplitude, but also of prolonged recovery. Under 

 the strong stimulation here employed, owing to persistent 

 molecular strain, the recovery did not become complete. 

 This is analogous to the contracture in strongly excited 

 muscle. Such persistent strain may be removed by mole- 

 cular vibration, the hastened recovery in the present record 



being the result of a tap. 

 Magnetic stimuli, individually 

 ineffective, become effective 

 by repetition. In fig. 365 is 



FIG. 364. Photographic Record or 

 Response and Recovery of Steel 

 under Moderate and Strong Mag- 

 netic Stimulus 



First pair of records show response and 

 recovery under moderate stimulus. 

 In the next two, stronger stimulus 

 induces response of greater ampli- 

 tude and incomplete recovery. 

 Molecular vibration by tap, at point 

 marked by down-arrow I , hastens 

 recovery. 



FlG. 365. Photographic Record 

 showing Ineffective Stimulus 

 made Effective by Repetition 



Asingle brief magnetic stimulation 

 induced little or no effect, but 

 when rapidly repeated thirty 

 times it became effective. 



seen a record of this. Tetanisation also induces the maxi- 

 mum effect of fusion as will be seen in the following chapter. 

 Tetanisation, again, induces interesting after-effects in mag- 

 netic responses, precisely the same as those seen in living 

 tissues. Under certain conditions, moreover, to be fully 

 described later, tetanisation, as we shall see, enhances the 

 subsequent responses, while under other conditions, by in- 

 ducing fatigue, it brings about their depression. 



I have already mentioned the fact that in addition to 



QQ2 



