CONDUCTIVITY 133 



other investigators, such as Hermann,^ Sspilmann and Luch- 

 singer, ^ Gad,^ Piotrowski* and Wedenski,^ have more or less 

 decidedly taken the stand that an actual separation of irritability 

 and of conductivity does not exist. The apparently contradictory 

 evidence as well as the conflicting theoretical views have been 

 cleared up by Werigo,^ Dendrinos,'' Noll^ and Frohlich.^ These 

 investigators have shown that the length of the narcotized stretch 

 of the nerve plays an important role in the obliteration of con- 

 ductivity. It has been found by the application of a stimulus 

 above the narcotized stretch of nerve, that the longer this stretch 

 is, the less is the reduction of irritability which obliterates the 

 excitation wave reaching this area. Further: The shorter 

 the stretch, the greater must be the reduction in irritability 

 before this result is brought about. (Figure 22.) In other 

 words, the conductivity in the narcotized nerve is dependent 

 upon the length and the irritability of the narcotized stretch. 

 From this observation the important fact is evolved, that 

 the wave of excitation meets with a decrement of its inten- 

 sity in the narcotized area. This decrement becomes larger as 

 the wave progresses through the involved stretch. Further it 

 is progressively increased as the amount of the irritability is 

 reduced. Finally, when the stretch is long enough, the wave 



\ Hermann: "Handbuch der Physiologic." Bd. II, I Leipzig 1879. 



2 Sspilmann und Luchsinger: "Zur Beziehung von Leitungs-und Erregfungsver- 

 mogen der Nervenfaser." Pfliigers Arch. Bd. 24, 1881. 



3 Gad: "Ueber Trennung von Reizbarkeit und Leitungsfahigkeit des Nerven." 

 (Nach Versuchen des Herrn Sawyers) Arch. f. Anat. u. Physiol, physiol. Abt. 1888. 



Derselbe: "Ueber Leitungsfahigkeit und Reizbarkeit des Nerven in ihren Bezieh- 

 ungen zur Langs und Querschnitts erregbarkeit." Nach Versuchen des Herrn Piotrow- 

 ski Arch. f. Anat. und Physiol, physiol. Abt. 1889. 



A Ptotrovoski: "Ueber Trennung von Reizbarkeit und Leitungsfahigkeit des Nerven." 

 Arch. f. Anat. u. Physiol, physiol. Abt. 1893. 



5 Wedenski: "Die fundamentalen Eigenschaften des Nerven unter Einwirkung 

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



The same: "Excitation, inhibition et narcose." Compt. rendus du v. Congres 

 internat. de Physiologie a Turin 1901. 



6 Werigo: "Zur Frage fiber die Beziehungen zwischen Erregbarkeit und Leitungs- 

 fahigkeit des Nerven." (Nach Versuchen von stud. Rajmist. Pfliigers Arch. Bd. 76, 

 1899. 



7 Dendrinos: "Ueber das Leitungsvermogen des motorischen Froschnerven." 



8 Noll: "Ueber Erregbarkeit und Leitungsvermogen des motorischen Nerven unter 

 dem Einfluss von Giften und Kiilte." Zeitsch. f. Allgem. Physiol. Bd. Ill, 1907. 



9 Fr. IV. Frohlich : "Erregbarkeit und Leitfahigkeit des Nerven." Zeitschr, f. 

 allgem. Physiol. Bd. Ill, 1904. 



