HIBERNATION 147 



THE HIBERNATION OF CERTAIN ANIMALS 



Bx the late WALTER L. HAHN, Ph.D. 



THE hibernation of animals is one of the most interesting phenom- 

 ena of nature. The word " hibernation " comes from the Latin 

 hibernare, meaning to go into winter quarters, but it has come to have 

 a more restricted meaning, and we understand by it a protracted condi- 

 tion of lethargy, during which the vital activities of an animal are more 

 or less completely suspended. 



Some of the simplest or one-celled animals, the infusoria, have the 

 ability to withstand extremes of cold and drouth for long periods by 

 forming hard coverings or cysts about themselves and in this condition 

 they may be completely dried up and blown about by the wind, reviving 

 when favorable conditions return, perhaps months afterward. 



This condition corresponds to the hibernation of higher animals 

 about as closely as any of the other activities of these simple organisms 

 correspond with the more complex life of the higher species. 



As far as I have been able to learn, there is nothing corresponding 

 to hibernation in those animals that are nearest the infusoria in the 

 scale of life, the sponges, corals, jelly-fishes, starfishes and the hosts of 

 other marine invertebrates. However, practically all insects in tem- 

 perate climates (excepting some that live in the water) pass the winter 

 in a dormant state. In some species the adult insect lives through the 

 winter, in others only the eggs, the larva? or the chrysalides survive. 

 In some cases the insect burrows into the ground or seeks protection else- 

 where; in others, the egg, larva, chrysalid or adult insect remains in 

 the most exposed situations in temperatures at times many degrees be- 

 low freezing point. 



Without attempting to enumerate all the kinds of animals that 

 hibernate or to discuss the general features of the phenomenon, I shall 

 merely call attention to the well-known fact that frogs, toads, snakes, 

 lizards and turtles, in temperate climates, seek protection during the 

 winter months in crevices among rocks or buried in the soil or mud ac- 

 cording to their especial habits. We will now pass on to a discussion of 

 the hibernation of certain well-known species of the highest class of the 

 animal kingdom, the mammals. 



The Bears 



I mention the hibernation of the bears here, not because I have any 

 new facts to contribute in regard to it or any personal observations to 

 record, but because that while the general fact of their hibernation is 



