316 IRRITABILITY 



ing excitations. Waller,^ Boruttau,^ Boruttau and Frohlich,^ 

 Tlwrner* and others have shown that the action current of the 

 nerve during the appHcation of tetanic stimulation becomes decid- 

 edly greater during a certain stage of narcosis or asphyxiation, 

 so that the wave of negative variation is higher than when the 

 nerve is excitated by a single induction shock. Frohlich^ first 

 threw light upon this subject in that he made the observation 

 that here a principle is involved which has far-reaching impor- 

 tance in the phenomena occurring in the organism. He showed 

 that as a result of fatigue, cold and narcosis, etc., the course of 

 excitation brought about by the single stimulation undergoes 

 retardation. These conditions within certain limits become more 

 favorable for the production of summation, because each succeed- 

 ing stimulus meets with a more incomplete recovery of excitation 

 than the one previously applied. In consequence of this, the irri- 

 tability of the system in the beginning of fatigue, or narcosis, or 

 immediately after the application of cold, is apparently increased. 

 This "apparent excitation," as it was called by Frohlich, depends, 

 however, in reality upon a beginning depression which is evident 

 in that the course of the individual excitations are lengthened by 

 this means. The irritability is likewise also reduced. Reinecke^ 

 later studied in further detail the retardation of excitation in the 

 muscle and attributed to this the characteristic property shown 

 in muscle in the so-called "reaction of degeneration." Fatigue, 

 asphyxia, cold, degeneration, in fact all factors which retard the 



1 Waller: "Observations on isolated nerve." Croonian Lecture, Philosophical 

 transactions. 1897. 



2 Boruttau: "Die Actionsstrome und die Theorie der Nervenleitung." Pfliigers Arch. 

 Bd. 84, 1901. 



Z Boruttau und Frohlich: "Electropathologische Untersuchungen. Ueber die 

 Aenderung der Erregungswelle durch Schadigung des Nerven." Pflugers Arch. Bd. 

 105, 1904. 



4 Thorner: "Die Ermudung des markhaltigen Nerven." Zeitschr. f. allgem. Physi- 

 ologic Bd. VIII, 1908, und Bd. X, 1910. 



5 Fr. IV. Frohlich: "Ueber die scheinbare Steigerung der Leistungsfahigkeit des 

 quergestreiften Muskels im Beginn der Ermudung (Muskeltreppe), der Kohlensaure- 

 wirkung und Wirkung anderer Narkotica (Aether, Alkohol)." Zeitschr. f. allgem. 

 Physiologic Bd. V, 1905. The same: "Das Princip der scheinbaren Erregbarkeits- 

 steigerung." Zeitschr. f. allgem. Physiologic Bd. IX, 1909. 



6 Fr. Reinecke: "Ueber die Entartungsreaction und eine Reihe mit ihr verwandter 

 Reactionen." Zeitschr. f. allgem. Physiologie Bd. VIII, 1908. 



