HIBERNATION: A PERIODICAL PHENOMENON. 



By J. P. Baumberger, Bussey Institution. 



Hibernation may be defined as the quiescent condition 

 characteristic of many organisms during winter. A number of 

 investigators have studied the phenomenon for the plant and 

 animal kingdoms and have assembled a large mass of facts as 

 to the physiological conditions and the habits of hibernating 

 organisms. The studies have also included the causes of this 

 quiescence and a number of hypotheses have been proposed. 



Confining ourselves to insects the most commonl}^ proposed 

 hypothesis is that low temperature or low mean temperature is 

 conducive to hibernation. In a previous paper^ the author 

 analysed an amount of temperature data with reference to the 

 date of hibernation of the Codling Moth and showed that in the 

 cases studied a marked lowering of average temperature or a 

 very low temperature did not immediately precede the date of 

 hibernation. The author has during the past two years carried 

 on some experiments with the banana fly {Drosophila melano- 

 gaster Meigen) with the object of determining whether or not 

 a hibernating period could be established by the stimulus of 

 low temperatures. In this experiment eggs, larvae, pupae and 

 adults of the same parents were kept in the ice box and in the 

 greenhouse. 



TABLE I. 

 Pupal Period. 



The proceedure was as follows: pupae were placed in the ice 

 box for ten days and then removed to the green house. At the 

 date of removal pupae which had just formed were also placed 

 in the greenhouse. The periods of time that elapsed before 

 emergence of the adults was then compared. The results show 



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