39O DAVID E. FINK. 



present in non-solanaceous foods as compared to potato tuber 

 and foliage. It is known that a diet rich in carbohydrates, as 

 for example, turnips or potatoes, increases the proportion of 

 lower fatty acids, while a diet rich in proteins diminishes this 

 proportion. If the percentage of the lower fatty acids increases 

 with the amount and kind of food, this fact may explain the 

 results shown in the above experiments, since tuber material is 

 rich in carbohydrates. 



It was previously pointed out that members of group 4, fed 

 non-solanaceous food plants and those beetles fed on peppers, in 

 general, gradually starved. The respiratory metabolism of such 

 animals manifests an extremely reduced oxygen consumption 

 and (in other experiments to be discussed later) a decreased CO 2 

 output. In control experiments, where nothing was fed, the 

 oxygen intake similarly was exceedingly diminished. 



PREPARATION FOR HIBERNATION. 



Of significance are the variations in weight recorded during 

 the preparation for hibernation. First generation beetles as 

 they emerged from pupation and before feeding averaged 0.1260 

 grams in weight. After feeding on foliage of the potato plant 

 for ten days, the weight averaged 0.2627 grams. A state of 

 quiescence or prehiber nation 2 followed, varying from three to 

 five days and was accompanied by a reduction of the water 

 content and elimination of the waste material from the digestive 

 tract, giving an average weight of 0.1879 grams. The increase 

 in weight accounts, in part, for the accumulation of reserve 

 nutrient material in the adipose tissues, and may, in addition, 

 indicate growth of somatic and germinal cells. Furthermore, 

 during prehiber nation a gradual lowering of all vital activities 

 takes place, the beetles afterwards entering the ground to 

 hibernate. 



Determinations of the water and fat content were made upon 

 groups of beetles as shown in Fig. 4. From an examination of 

 these it is evident that during active feeding, the average water 

 and fat content was 76.4 and 7.8 per cent, respectively. During 

 prehibernation, the average water and fat content was 59 and 



2 The term prehibernation is used to designate the quiescent state that occurs 

 when feeding ceases and before the beetles burrow in the ground. 



