Vol. XXV. July, i 9 i 3 . No. 2. 



BIOLOGICAL BULLETIN 



THE REACTIONS OF CERTAIN ANIMALS TO 



GRADIENTS OF EVAPORATING POWER OF 



AIR. A STUDY IN EXPERIMENTAL 



ECOLOGY. 



VICTOR E. SHELFORD. 



WITH A METHOD OF ESTABLISHING EVAPORATION GRADIENTS BY 

 V. E. SHELFORD AND E. O. DEERE. 



CONTENTS. 



PAGE 



I. Introduction 79 



II. A Method of Establishing Evaporation Gradients by V. E. Shelford and 



E. O. Deere So 



III. Material 84 



IV. Experimental Results 85 



1. Dry Air 85 



2. Rapidly Flowing Air 97 



3. Warm Air i oo 



4. Death through Evaporation 102 



V. General Discussion and Comparison 104 



1. Rating of the Species 104 



2. Comparison 105 



3. Physiology of Water Withdrawal and Water Starvation 107 



4. Importance of Evaporation Rate no 



VI. Summary 1 13 



VII. Acknowledgments and Bibliography 114 



I. INTRODUCTION. 



Aside from studies of the hygienic workers (Rubner and others), 

 studies of mountain sickness, and other physiological phenomena 

 of high altitudes and reduced atmospheric pressure (Cohnheim 

 and others), little attention has been given to the effect of loss 

 of water upon land animals. Since evaporation is determined 

 by air movement, humidity, pressure, temperature, and indi- 

 rectly by illumination, most of the so-called physical factors are 

 measured in combination by instruments measuring evaporation. 



79 



