JOURNAL OF ANIMAL BEHAVIOR 



Vol. 4 JULY-AUGUST, 1914 No. 4 



THE FACTORS DETERMINING THE VERTICAL 

 MOVEMENTS OF DAPHNIA 



LEE RAYMOND DICE 

 From the Zoological Laboratory of the University of California 



CONTENTS PAGE 



Introduction. 



Part I. Experimental 231 



Phototaxis in Relation to: 



Light Intensity 231 



Temperature 235 



Chemical Content of Water 236 



Mechanical Stimulation 236 



Time of Day 237 



Geotaxis in Relation to: 



Light Intensity 237 



Temperature 242 



Chemical Content of Water 244 



Mechanical Stimulation 245 



Time of Day 245 



Locomotor Activity in Relation to: 



Light Intensity 245 



Temperature 246 



Chemical Content of Water 248 



Mechanical Stimulation 248 



Time of Day 249 



Thermotaxis 249 



Chemotaxis 249 



Pressure - 249 



Part II. Discussion 250 



Observed Vertical Movements in Daphnia 250 



Vertical Movements Caused by: 



Changes in Light Intensity 253 



Changes in Temperature 255 



Mechanical Stimulation 257 



Changes in Chemical Content of the Water 258 



Aging of Individuals ' 258 



General Features of Behavior in Daphnia 259 



Reversal of Geotaxis in other Plankton Animals 262 



Summary 263 



Literature 264 



