MULTIPLE RESPONSE OF NERVE 



539 



of spasmodic contractions. This also we may regard as 

 caused by multiple excitations induced in the nerve. And 

 the correctness of this supposition I have been able to 

 verify by experiment. As 

 the individual responses in 

 these multiple series were of 

 fairly large amplitude, I ex- 

 pected to be able to obtain 

 a record of such a series 

 by an ordinary magnification 

 on smoked glass. In order 

 to 'obtain this record under 

 normal conditions a stream 

 of air, bubbling through 

 water, was passed through 

 the chamber at a uniform 

 rate. Owing to the run- 

 down of the latent energy 

 in the nerve, we are able 

 to observe a consequent 

 growing relaxation. By the 

 manipulation of a stop-cock 

 the air is passed through 

 a calcium chloride tube, in- 

 stead of a vessel containing 

 water. In this way the nerve 

 is quickly subjected to dry 

 air instead of moist vapour. 

 This substitution is repre- 

 sented in the record by an 

 upward arrow t, and it will 



FIG. 326. Initiation of Multiple Re- 

 sponse by Drying of Nerve 



The nerve, owing to growing sub- 

 tonicity, was showing a growing 

 relaxation, as seen in the first part 

 of the record. Air passed through 

 CaCl 2 tube, and, thus dried, was 



now passed through nerve-chamber 

 at point marked with upward arrow 

 f . This gave rise to a large con- 

 tractile response, followed by sub- 

 sequent multiple responses. Original 

 record on smoked glass here reduced 

 photographically to 5. 



be noticed how at this point 

 the relaxation is suddenly converted into excitatory con- 

 traction (fig. 326). Under this process of drying, this single 

 contractile movement is followed by a long-continued series 

 of multiple responses, here seen to fall into a somewhat 

 irregular periodicity. 



