CHAPTER XXXVI 



MULTIPLE RESPONSE OF NERVE 



Great sensitiveness of the high magnification Kunchangraph Individual con- 

 tractile twitches shown in tetanisation of nerve Sudden enhancement of 

 mechanical response of nerve on cessation of tetanisation Secondary excita- 

 tion Multiple mechanical excitation of nerve by single strong stimulation 

 Multiple mechanical excitation of nerve by drying. 



WE have already seen that, in order to detect the excitatory 

 changes in nerve by the electrical method, the moderate 

 sensitiveness of an ordinary galvanometer has to be exalted 

 more than a million times. Galvanometric indications, more- 

 over, are liable, as we have seen, to be complicated by the 

 occurrence of differential effects at the two contacts. In 

 the Kunchangraphic method of record, however, there is no 

 possibility of such complications, for the response curve here 

 represents the direct effect of stimulus. We also saw that, 

 according to this method, a very moderate magnification 

 would give us all the variations that could be detected by 

 the most sensitive galvanometer, and, besides this, owing to 

 its simplicity, it makes it possible to observe other phenomena, 

 whose occurrence the galvanometer could not satisfactorily 

 have demonstrated. 



Such a magnification, however, as I have already said, is 

 in its first stage only. With due precautions it is possible 

 to obtain a Kunchangraphic magnification of a hundred 

 thousand times. It will easily be seen that this places at 

 our disposal an instrument of incomparable sensibility, by 

 whose aid many of the phenomena of the nervous change, 

 hitherto beyond our power of observation, may be brought 

 within the sphere of investigation. 



