THE DESICCATION OF ROTIFERS 



D. D. WHITNEY 

 Cold Spring Harbor, Long Island, N. Y. 



The general statement often found in text-books that 

 "Adult rotifers can survive prolonged desiccation and 

 resume active life when again placed in water, ' ' seems to 

 have been made without sufficient warrant. 



While working with the rotifer, Asplancha brightwellii, 

 my attention was repeatedly called to the fact that when 

 the water became sufficiently evaporated so as to expose 

 only a portion of the body of the rotifer to the air it 

 never recovered when placed again in a larger quantity 

 of water and soon died. Doubt as to the truth of the 

 general statement regarding desiccation naturally arose 

 and in consequence a series of experiments were carried 

 out to test the matter. 



Forty-five species of rotifers that were collected in the 

 various ponds and pools in the vicinity of Cold Spring 

 Harbor, New York, were dried at room temperature, 

 from a few hours to several days, during the months of 

 July and August. They were dried without being ex- 

 posed to direct sunlight in a hollow ground slide, upon 

 filter paper, in sediment taken from the water in which 

 the rotifers lived, and also in sediment mixed with sand. 

 Masses of the water plants, Lemna, Myriophyllum and 

 others among which many species lived were also dried. 

 After the water seemed to have been completely evapo- 

 rated fresh spring water was added and those* animals 

 that ever revived did so within ten to twenty minutes 

 after the water was added. Drying the rotifers in masses 

 of sediment and in sediment mixed with sand was found 

 to lead to more recoveries. 



In all experiments many species were dried in the same 

 lot and in nearly all of them these were mixed with roti- 

 fers which were known to withstand drying. If none of 

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