Vol. XXXII. February, 1917. No. 2 



BIOLOGICAL BULLETIN 



REACTIONS OF AMEBA TO LIGHT AND THE EFFECT 

 OF LIGHT ON FEEDING. 



ASA A. SCHAEFFER, 

 DEPARTMENT OF ZOOLOGY, UNIVERSITY OF TENNESSEE. 



CONTENTS. 



Introduction 45 



Experiments with Light 49 



White light 49 



Red light 50 



Blue light 53 



Violet light 56 



Green light 57 



Yellow light 58 



Orange light 58 



Experiments with dark beams 59 



Reactions toward solid particles when stimulated at the same time by beams 



of light or of darkness 62 



Conclusions 67 



Summary 7 



Bibliography 71 



Explanation of plates 74 



Table of abbreviations 74 



INTRODUCTION. 



The reactions of ameba-like organisms to light have been 

 studied by a number of investigators in order to determine whether 

 "naked" protoplasm is capable of responding to light waves. 

 Whenever intense light was used as a source, amebas, pelomyxas 

 and plasmodia reacted negatively, and as a consequence it was 

 tacitly assumed that in general naked, "undifferentiated," 

 protoplasm reacted negatively to light. 



But speaking now only of experiments performed on amebas, 

 for I do not wish to leave the impression that in my opinion what 

 is true of the behavior of amebas toward light holds also for 



45 



