A PRELIMINARY ACCOUNT OF SOME CYTOLOGICAL 

 CHANGES ACCOMPANYING DESICCATION. 



LOUIS M. HICKERNELL, 

 PRINCETON UNIVERSITY. 



The ability of certain rotifers, tardigrades and nematode 

 worms to withstand periods of desiccation has been a subject of 

 investigation for many biologists throughout a period of more 

 than two hundred years. Beginning with von Leeuwenhoek in 

 1701 and extending to the present time, researches have been 

 carried on at intervals, in the case of the Bdelloid rotifers, with 

 the object of determining whether or not these animals can 

 undergo a true desiccation. The results of the several authors 

 have shown a striking variance, in fact in some cases the conclu- 

 sions of one worker have been directly opposed to those of some 

 other who used the same species of animal in his experiments. 

 The latest publication upon this subject is that of Jacobs ('09) 

 who worked on the Bdelloid rotifer, Philodina roseola. He con- 

 cludes, after prolonged experimentation and as a result of chem- 

 ical and physical tests as well as by other indirect methods, that 

 this animal undergoes a true desiccation; that at all times the 

 cuticle is freely permeable to water and gases and that no evidence 

 of a waterproof cyst can be found. He notes further that desicca- 

 tion is usually followed by a period of reproductive activity. 

 The foregoing conclusions together with others not bearing 

 directly upon the subject of this paper have been confirmed 

 during the course of this study. 



Jacobs, while conducting his investigation in a very thorough 

 manner, made no attempt to determine, from a histological or 

 cytological point of view, the condition of the tissues of the desic- 

 cated animals as compared with those in the normal individual. 

 To the knowledge of the author no comparison of this sort has 

 been attempted by any investigator up to the present time. 

 At the suggestion of Dr. E. G. Conklin, I have undertaken an 

 inquiry into this last question and present here a brief account 



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