Hibernation. 125 



bernate, for instance ; but the most it can do, is to 

 preserve those animals that already have this pow- 

 er in the greatest perfection. But in the conditions 

 of hibernation we find an exceedingly complicated 

 machinery for the preservation of animal life, vary- 

 ing much according to the species. There is a 

 chain of agencies of which Instinct is only one link. 

 Hibernating animals of the higher rank, feed upon 

 food that is abundant in the autumn. Their appe- 

 tite is then voracious, and fat accumulates to an un- 

 wonted degree. So far. Instinct has no part in the 

 work except in the procuring of food. But now it 

 comes in as chief actor, to impel and guide the ani- 

 mal in preparing a nest or retreat for his winter's 

 sleep. When this is done, function takes up the 

 entire work again, lessens the rate of breathing and 

 lowers the whole vital activity, so that the animal 

 lives for months without eating, and yet comes out 

 in good condition when nature has once more 

 spread a table for him. In the case of other ani- 

 mals, especially in the case of some reptiles and in- 

 sects, there is complete torpor. But in every case 

 we see these agencies. Instinct and Function, work- 

 ing together, or rather working in succession, each 

 supplementing the other. 



It may be said that cold has a tendency to 

 lower vitality, and so by degrees these functional 

 changes are produced and the animal, or more strict- 

 ly the species, forms a habit which we call Instinct 

 But if we go to certain hot countries where great heat 

 and drought are combined, we find animals secre- 

 ting themselves by Instinct and becoming torpid in 



