HIBERNATION IN THE POTATO BEETLE. 



403 



were negative since no typical characteristic blueing of guaiacum 

 took place. Similar tests performed with active and starving 

 beetles, gave striking reactions (blueing of guaiacum) with 

 esophagus, stomach, tip of rectum, tissues, body fluids, testes 

 and immature ova. 



o 



C_J> 



c 



Minutes 



FIG. 13. The catalase activity per minute per gram body weight of organism. 

 Ordinates show the oxygen evolved in cubic centimeters, abscissas as minutes. 

 A, young beetles; B, aged beetles; C, hibernating beetles; D, starving beetles. 



Although the catalases and oxidases may possess specific 

 functions in the active animal, in the hibernating forms these 

 enzymic activities obviously become greatly reduced or seemingly 

 absent. 



SUMMARY. 



1. The results of the food experiments indicate that potato 

 beetles of the first generation when fed on tubers and fruit of 

 the potato, tomato, and eggplant require 13 days feeding to 

 enter hibernation, w r hile those fed on foliage of the same plants 

 need 16 days. Beetles fed on potato foliage for six days followed 

 by a non-solanaceous food required 23.6 days feeding before 

 hibernation, and produced a mortality of 55 per cent. Those 

 fed on pepper plants or on non-solanaceous foods do not hiber- 

 nate, but die of starvation. 



2. Respiratory metabolism determinations show that the 

 oxygen consumption of beetles fed on tubers or fruit of solana- 

 ceous plants is less than of those fed on foliage. When fed on 

 non-solanaceous foods, the reduced oxygen intake recorded was 



