l6o THE INDUSTRIES OF ANIMALS. 



and actively hunts fish in ponds and rivers. But 

 when fishing is over, it likes to keep dry and at the 

 same time sheltered from terrestrial enemies. Its 

 dwelling must also present an easy opening into the 

 water. In order to fulfil all these conditions, its house 

 consists first of a large room hollowed in the bank at 

 a level sufficiently high to be beyond reach of floods. 

 From the bottom of this keep a passage starts which 

 sinks and opens about fifty centimetres beneath the 

 surface of the water. It is through here that the 

 Otter noiselessly glides to find himself in the midst 

 of his hunting domain without having been seen or 

 been obliged to make a noisy plunge which would 

 put the game to flight. If this were all, the hermeti- 

 cally-closed dwellingwould soon become uninhabitable, 

 as there would be no provision for renewing the air, 

 so the Otter proceeds to form a second passage from 

 the ceiling of the room to the ground, thus forming a 

 ventilation tube. In order that this may not prove a 

 cause of danger, it is always made to open up in the 

 midst of brushwood or in a tuft of rushes and reeds. 



Marmots also are not afraid of the work which will 

 assure them a warm and safe refuge in the regions 

 they inhabit, where the climate is rough. In summer 

 they ascend the Alps to a height of 2,500 to 3,000 

 metres and rapidly hollow a burrow like that for 

 winter time, which I am about to describe, but smaller 

 and less comfortable. They retire into it during bad 

 weather or to pass the night. When the snow 

 chases them away and causes them to descend to a 

 lower zone, they think about constructing a genuine 

 house in which to shut themselves during the winter 

 and to- sleep. Twelve or fifteen of these little animals 

 unite their efforts to make first a horizontal passage, 



