29 



larvae were kept in two cages with plants of golden rod. In one 

 cage, as soon as the new growth appeared in the spring, the larvae 

 commenced to feed upon it, but the plant being unable to maintain 

 headway against their attacks, when the cage was examined the 

 larva? were found to be all dead of starvation. In the other cage 

 the plant died during the winter, but when this cage was examined 

 at the same time as the other, the larvae were found to be alive and 

 healthy. Not having been able to break their winter's fast, they 

 had been able to prolong it for some weeks, while the others having 

 once recommenced feeding were not able to survive subsequent 

 starvation. 



Dr. Chapman concludes that the constancy of the occurrence of 

 the habit in any species of insect, and the persistency of attempts 

 to hibernate under abnormal conditions, prove that it is a matter 

 of instinct and inherited habit rather than the immediate conse- 

 quence of definite physical conditions. For the origin of the 

 habit he suggests that we must look to the quiescence of protoplasm 

 at a low temperature and under starvation, and that hibernation 

 should be considered a function of the protoplasm rather than of 

 the organism as a whole. It would thus be seen in its simplest 

 form in the case of those species that pass the Aviuter as an egg or 

 pupa. 



Not only may any one of the four main stages of an insect's 

 life be selected by a species as that best adapted for the purpose of 

 hibernation, but usually each species remains quite constant in this 

 respect. It seems, indeed, as though the capacity for hibernation 

 were limited, as regards any particular species, to the one stage in 

 its life. Experiment (17) seems to show that if, by any means, an 

 insect can be induced to pass beyond its normal hibernating stage 

 before winter overtakes it, it has then passed beyond its capacity for 

 hibernating, and will perish if not fed frequently (17). In a few 

 cases this capacity for hibernating is more elastic ; Netneophila 

 planta/iinis, for example, will hibernate almost as readily in the 

 pupal as in the larval state, while a few species such as Arctia raja 

 and Pliisia (/aiiinia can hibernate in practically any stage. With 

 most insects the capacity for hibernation is limited not only to one 

 of the four chief stages, but usually to a definite period in that 

 stage. An insect that wmters as an egg, for example, may do so 

 while the egg is " fresh," so to speak, before the development of 

 the contained embryo has commenced, or development may be 

 already complete, and the young larva ready formed within the 



