PHYSICAL BASIS OF SENSATION 649 



positivity. The change induced by strong stimulus, on the 

 other hand, was of contraction and galvanometric negativity. 

 In the terminal motile indicator also, there are two 

 different modes of response of opposite signs namely, 

 expansion and contraction. In the highly excitable muscle, 

 the occurrence of the former of these, brought about, as it is, 

 by very feeble stimulus, is not easy to demonstrate. Bearing 

 in mind, however, the fact that in nerve positive response is 

 more easily obtained when the excitability is depressed, 

 I succeeded in obtaining positive expansional response of the 

 muscle, in a nerve-and-muscle preparation of frog, which had 

 been depressed by the anaesthetic action of chloroform. At 

 a certain stage of anaesthetisation, the response of the muscle 

 under stimulation of the 

 nerve was found to take 

 place by expansion, 

 followed by recovery. 

 Just as in a nerve in 

 a somewhat depressed 

 condition, successive 



P IG. 399. Abnormal Response of Muscle by 

 Stimuli evoke positive Relaxation, followed by Normal Response 



response converted later of Contraction 



. , . The 1 first two responses by relaxation are 



into normal negative, followed by two contractile responses. 



so, in the muscle-pre- 

 paration described, the abnormal positive was followed by 

 the normal negative response. In fig. 399 I give a photo- 

 graphic reproduction of the myographic record obtained on 

 a smoked-glass surface. 



In all these different effects we obtain, by means of the 

 mechanical response of the terminal organ, what is merely 

 a parallel expression of changes occurring in the nerve itself. 

 As in the nerve, so also in the muscle, there are two different 

 kinds of responsive expression namely, expansion and con- 

 traction. Thus we see that the various manifestations 

 registered by different modes of indication are only so many 

 diverse expressions of the same fundamental molecular 

 changes. 



