142 IRRITABILITY 



stretch the capabiHty of conductivity disappears, and indeed 

 simultaneously for the weakest as well as the strongest stimuli. 

 If it is assumed that weak stimuli bring about weak excitations 

 in the nerve fiber, it must most certainly be expected that on the 

 cessation of the response, weak stimuli applied at the central 

 nerve end would still, by slight increase of the intensity of stimu- 

 lation, be followed anew by reaction in the muscle. This is all 

 the more to be expected, because the irritability of the narcotized 

 stretch, as shown by stimulation with the electrodes inside the 

 chamber, very gradually decreases, so that within the chamber 

 stimuli of moderate strength are still effective. Instead the capa- 

 bility of conduction is completely obliterated, and even the strong- 

 est stimuli, applied to the end of the nerve, produce no response 

 in the muscle. This in turn does not agree with the assumption 

 that the intensity of excitation varies with the strength of the 

 stimulus in the individual nerve fiber. The facts here alluded to 

 are, therefore, either not correct, or the intensity of excitation 

 in the individual nerve fibers is independent of the strength of the 

 stimulus, and the view which we have entertained up to the 

 present in this respect is incorrect. 



In order to examine these facts once more on an extensive 

 scale, and at the same time obtain an understanding of the devel- 

 opment of the decrement in the narcotized stretch, I have re- 

 quested Dr. Lodholz to register as many accurate curves as pos- 

 sible in which the positions of the secondary coil of an inductorium 

 are the ordinates indicating the threshold of stimulation at four 

 points of a nerve stretch. Of these points three are situated at 

 prescribed distances from each other in the narcotized or asphyxi- 

 ated stretch; the fourth is centrally placed. (Figure 34.) As 



Fig. 24. 



