AtTTHOH'S ABSTRACT OF THIS PAPER ISSUED 

 BY THE BIBLIOGRAPHIC SERVICE, MARCH 31 



THE PHYSIOLOGY OF THE NERVOUS SYSTEM OF 



THE TUNICATE 



» 



I. THE KELATION OF THE NERVE GANGLION TO SENSORY 



RESPONSES 



EDWARD C. DAY 



Department of Zoology, University of Cincinnati 



FIVE FIGURES 



CONTENTS 



Introduction 307 



Tactile reactions of normal Ascidia mentula 310 



A. Observations on unstimulated individuals 310 



B. Responses to tactile stimulation 311 



Effect of operations upon the tactile response 311 



A. Slitting the siphons 311 



B. Amputation of siphons 312 



C. Extirpation of the ganglion 315 



Reactions of Ascidia mentula to chemical substances 317 



Reactions of Ascidia mentula to vibrations 319 



Summary of reactions of Ascidia mentula 320 



Sensory reactions of Ascidia atra Lesueur 322 



Experiments on Ciona intestinalis 323 



Reaction of tunicates to light '. 327 



Summary of results of previous investigations 333 



Bibliography '. 335 



INTRODUCTION 



When one beholds a sohtary ascidian in normal surroundings, 

 one comes to the conclusion that such an organism needs no 

 complicated nervous system to cope with the exigencies of its 

 environment. Unless the observer disturbs the ascidian by 

 stamping on the sand, he may watch it for a considerable length 

 of time without detecting any movements which would indicate 

 it to be an animate object. From time to time, however, it is 



307 



