THE REFRACTORY PERIOD AND FATIGUE 183 



oxygen and only completely asphyxiates when the last trace of 

 oxygen is removed, and further that recovery takes place within 

 a fraction of a minute if the oxygen is again supplied. These 

 experiments which have been carried further by Frohlich 1 were 

 afterwards confirmed in other laboratories, 2 and form the basis 

 for proving the existence of fatigue of the medullated nerve. 

 Shortly after, Frohlich 3 was able to demonstrate symptoms of 

 fatigue in the medullated nerve. He found that the refractory 

 period of the nerve, which, as previously mentioned, Gotch and 

 Burch fixed at about .005 second duration, was prolonged by 

 oxygen deficiency to .1 second, so that stimuli following each 

 other oftener than ten times per minute produced merely single 

 initial contractions in the muscle concerned, that is, in a series 

 of stimuli of which the intervals are less than .1 per second, only 

 the first produces 'response, whereas the following occur in the 

 refractory period, brought about by those preceding, and are, 

 therefore, inoperative. The nerve is fatigued by the quick suc- 

 cession of stimuli. The normal nerve on the contrary invariably 

 responds, as known, to an even more rapid succession of stimuli 

 with a rhythmical excitation corresponding to the number of 

 stimuli and which is manifest in the muscle by a tetanus. This 

 again confirmed the identity of fatigue with the prolonged re- 

 fractory period, conditioned by the relative want of oxygen. It 

 likewise explained the conditions of the analogous behavior that 

 Wedensky 4 had observed in the narcotized nerve, but had neither 



1 Fr. W. Frohlich: "Das Sauerstoffbediirfniss des Nerven." Zeitschr. f. allgem. 

 Physiologic Bd. Ill, 1904. 



2 K. H. Baas: "Zur Frage nach dem Sauerstoffbediirfniss des Froschnerven." 

 Pfliigers Arch. Bd. 103, 1904. 



K. Frick: "Die Abhangigkeit der Erregbarkeit des peripherischen Nerven vom 

 Sauerstoff." Inaugural Dissertation vorgelegt der medicinischen Facultat der Univers. 

 Berlin (Aus dem physiologischen Institut der Univers.). Berlin 1904. 



Uchtomsky und Dernoff: "Zur Frage nach dem Sauerstoffbediirfniss der Nerven." 

 Travaux du laboratoire de Physiologic a 1'universite de St. Petersbourg II Annee 

 1907. 



3 Fr. W. Frohlich: "Die Ermiidung des markhaltigen Nerven." Zeitschr. f. allgem. 

 Physiologic Bd. Ill, 1904. 



4 Wedensky : "Die fundamentalen Eigenschaften des Nerven unter Einwirkung 

 einiger Gifte." Pfliigers Arch. Bd. 82, 1900. 



The same: "Erregung, Hemmung und Narkose." In the same place. Bd. 100, 

 1903. 



