THIRTEENTH LECTURE. 



DO THE REACTIONS OF LOWER ANIMALS DUE 

 TO INJURY INDICATE PAIN-SENSATIONS? 



W. W. NORMAN. 



ASSOCIATE PROFESSOR OF BIOLOGY, UNIVERSITY OF TEXAS. 



A BRIEF note by me concerning pain-sensations in the lower 

 animals appeared in Pfluger s Archiv for I896. 1 It was my aim 

 to give experimental proof that the reactions of lower animals 

 upon injury furnish no safe evidence of pain-sensations. For 

 these experiments chiefly the earthworm (Allolobophora foetidd) 

 was used. 



It had already been observed by Friedlander 2 that when an 

 earthworm is cut in two in the middle, the two halves react 

 differently the anterior half crawling away and burying itself 

 like a normal worm, the posterior end making strong winding 

 and jerking motions. [Unmittelbar nach der Operation machen 

 sie (die gekopften Wiirmer) heftige schlagende und windende 

 Bewegungen.] Loeb 3 had observed similar motions in other 

 worms similarly treated. 



If Friedlander had carried his experiment further, namely, if 

 he had cut each half of the already halved worm in two in the 

 middle, the results would have become, indeed, still more strik- 

 ing. It is here that my experiment presents an essentially new 

 point. 



1 " Diirfen wir aus den Reactionen niederer Thiere auf das Vorhandensein von 

 Schmerzempfindungen schliessen ?" PJUlger's Archiv, Bd. Ixvii, p. 137. 



2 Friedlander, " Ueber das Kriechen der Regemviirmer," Biol. Centralblatt, 

 Bd. viii. 



3 Loeb, J., " Beitrage der Gehirnphysiologie der Wurmer," Pfliiger's Archiv, 

 Bd. Ivi. 



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