1917] Hibernation: A Periodical Phenomenon 181 



ature falls. In this case the condition can be recognized by a 

 pause in feeding and in growth. The Codling Moth has 

 already been cited as an example of this peculiarity. It might 

 also be said that the food of the insect has not become less 

 available at this period. Other common insects which hibernate 

 as larvae at a definite date irrespective of low temperatures are 

 the Woolly Bear (Isia Isabella) and an Arctiid ( Apantesis nais) . 

 This "habit" was studied in 1915, especially with reference 

 to its independence of stimulii from relative humidity. 



The proceedure was as follows : Different relative humidities 

 were maintained by solutions of H2SO4 of various sp. gr. as 

 suggested by Woodworth^ and which I calculated from figures 

 given by Richards."* I have plotted the curve below from 

 Richard's figures and used the formula accompanying it in the 

 Volume calculations. (Figure 1). 



The solutions (200 cc.) were placed in battery jars (capacity 

 2000 cc.) with broad ground edges, which were vasalened and 

 covered with a glass plate. Inside these battery jars, supported 

 over the H2SO4 by square glass dishes, were placed glass jars 

 with a covering of cloth net in which the caterpillars were kept. 

 Food was introduced daily into the jar and the sulphuric acid 

 solution was changed every two weeks. The effects of different 

 humidities was very apparent on the food introduced. In 

 this work, due to the variation in temperature the humidity 

 of any bottle also varied, but this change being equal in each 

 bottle, the difference between bottles remained uniform. The 

 moisture absorbed from food and insects by the H2SO4 is a 

 source of error but not a great one. 



The data derived from these experiments are shown in 

 tables II and III. 



