400 DAVID E. FINK. 



those five or more months 6 days. During the interval of 

 restoration they are decidedly inactive, negatively heliotropic 

 and do not feed. 



Extensive experiments carried out during the winter with the 

 view of hastening recovery proved fruitless. In every instance 

 hibernating beetles when removed from the ground and placed 

 with food persistently indicated tendencies to burrow themselves 

 in again. In those cages not provided with soil the beetles 

 remained inactive on the side or bottom of the cage without 

 feeding. 



Both Bodine (4) and Sanderson (20) found that the rate of 

 recovery was quickest with animals brought in later in the 

 hibernating period. Sanderson, however, concluded that sub- 

 jecting hibernating forms to low temperature had the effect of 

 producing a more complete rest than at a higher temperature. 

 In view of additional experiments performed by the author a 

 different interpretation may be attributed to the above results. 

 For example, beetles reared in the greenhouse hibernated the 

 latter part of March and were kept at a comparatively high 

 temperature (65-95 F.) in the greenhouse. On July n, they 

 were found issuing from the ground in the cages, exhibiting normal 

 activities such as feeding, mating, etc. In these experiments, 

 therefore, cold was not essential for a complete rest. Further- 

 more, the depth at which potato beetles normally hibernate in 

 the soil (10-18 inches) precludes the assumption of a specific 

 influence of low temperature, or of the necessity of subjecting 

 them to prolonged periods of cold. On the contrary, experi- 

 mental evidence demonstrates a rhythmical period of rest 

 irrespective of temperature. 



Adjustment oj the Water Content. 



Of paramount importance to the animal during recovery and 

 before feeding is possible, is an adjustment of its water content 

 to normal. The need for actual contact of the animal with 

 water at different intervals seems to be essential. Whether 

 moisture may also be absorbed through the integument is not 

 definitely known. 



In the following experiments beetles recovering from hiber- 

 nation were kept in cages with abundance of food under the 



