THE VITAL LIMIT OF EXSICCATION OF CER- 

 TAIN ANIMALS. 



F. G. HALL, 

 ZOOLOGICAL LABORATORY, UNIVERSITY OF WISCONSIN. 



CONTENTS. 



Page 



I. Introduction 31 



II. Method of determining the vital limit 33 



Apparatus 33 



Plan of experiments 36 



\Yater content determination 37 



III. Experimental results 37 



Annelida - Earthworm 37 



Leech 39 



Insecta Meal worm 40- 



Amphibia Salamander 41 



Frog 41 



Reptilia Snake 43 



Turtle 43 



Lizards 44 



Mammalia Mice 45 



IV. General discussion and summary 4<s 



V. Bibliography 50 



INTRODUCTION. 



Water is one of the most important constituents of living mat- 

 ter. The water content of animals varies from 50 to nearly 100 

 per cent, of the total body weight. All living matter appears to 

 live in water. Not only is this true of the simplest forms of life, 

 the Protozoa and the Protophyta, which are hardly more than 

 naked protoplasm, but it is also true of the more complex organ- 

 isms where lymph, blood, and sap are found as liquids ; the imme- 

 diate environment of the individual cell. Any change in the 

 amount of water present may interfere with the activities of the 

 cell. Yet it is a familiar fact to zoologists that many animals will 

 endure considerable exsiccation. 



One hundred, and fifty years of experimentation has shown 

 that some animals become immobile when gradually dried out, 

 and are apparently dead. This condition Preyer (1891) called 

 "anabiosis." Leeuwenhoek was perhaps the first to observe this 

 phenomenon in 1701. He found that Rotifera and Tardigrada 



