382 DAVID E. FINK. 



in the presence of an abundance of food and warmth remain 

 impassive. This has led to the conclusion that hibernation is 

 some inherent, deep seated phenomenon. Recent studies by 

 Carlier (8), Rasmussen (18), Sheldon (22) and others, upon the 

 nature and function of the so-called hibernating gland, show it 

 widely present in mammals. 



The literature on physiological studies of hibernating insects 

 is not so extensive. Baumberger (i), Bodine (3), Breitenbecher 

 (6), Roubaud (19), Sanderson (20), Tower (24) and others, 

 however, have investigated problems of temperature, moisture, 

 and gaseous exchange as they relate to insects. According to 

 Baumberger (2), hibernation has resulted from the repeated 

 effect of winter upon the species and the rhythmical phenomenon 

 has been determined by the habits of the insect. Roubaud (19) 

 recently advanced the view that a lowered metabolic activity 

 permits a progressive physiological purification. According to 

 this author, two factors, anhydrobiosis , and athermobiosis (dehy- 

 dration and absence of heat), in themselves inhibitory, become 

 the unexpected factors of reactivation by favoring the processes 

 of excretion during dormancy. 



Most investigators w-hether dealing with hibernation in verte- 

 brates or invertebrates agree that the influence of temperature 

 in the process is subordinated, and that hibernation is preceded 

 usually by a period of extensive feeding and a consequent reduced 

 metabolic activity. It is also well known that food is an im- 

 portant factor in influencing the habits of animals. The manifold 

 instances of food storage indicate a varying adaptability, the 

 most significant being the storage within the body of the animal 

 of reserve nutrients in the form of fat. 



With insects the phenomenon of hibernation is unique, because 

 it may occur in any stage of the life cycle of different insects, 

 from the egg to the adult. It seemed advisable, therefore, to 

 investigate the problem of nutrient storage in insects and to 

 determine the specific mode of its utilization during the progress 

 of hibernation. 



This contribution presents the results obtained from physio- 

 logical studies on the potato beetle, Leptinotarsa decemlineata 

 Say, before, during, and after hibernation. 



