THE EFFECTS OF DESICCATION ON THE ROTIFER 

 PHILODINA ROSEOLA 



BY 



MERKEL HENRY JACOBS 



With One Figure 



I Introduction 207 



II Historical 210 



III Structure and natural history of Philodina 217 



rV Behavior of Philodina 220 



1 Behavior under normal conditions 220 



2 Behavior at the onset of desiccation 222 



V Visible changes attending a process of desiccation 223 



VI Degree of desiccation attained by Philodina 227 



1 The views of Davis and others 228 



2 Evidence for the view that a true desiccation occurs, 231 



VII Effect of desiccation on the life processes of Philodina 236 



1 Injurious effects of desiccation 236 



2 Influence of the previous condition of the animal 237 



3 Influence of the conditions attending the desiccation 238 



a Effect of rapidity of drying 238 



h Eff'ect of temperature at which drying occurs 242 



c Effect of duration of desiccation 244 



d Effect of alternations of moisture and dryness 244 



e Effect of intensity of desiccation 246 



/ Effect of temperature on mortality 248 



4 Conditions of the life processes in a dried animal 249 



5 Effect of desiccation on egg production 252 



Vni Summary 260 



IX Bibliography 262 



I INTRODUCTION 



It has long been known that various animals, among them 

 certain of the rotifers, tardigrades, and the smaller nematode 

 worms, can survive conditions fatal to most other organisms. 

 Although normally living in water, or at least under conditions 

 of moisture, these animals may be dried for long periods of time 

 without serious injury. They are found in countless numbers in 



The Journal of Experimental Zoology, vol. vi, no. 2. 



