DWELLINGS 1615 



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 dwelling would soon become uninhabit- 

 able, as there would be no provision for renewing 

 the air, so the otter proceeds to form a second pas- 

 sage 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 ani- 

 mals unite their efforts to make first a horizontal pas- 

 sage, which may reach the length of three or four 

 metres. They enlarge the extremity of it into a 

 vaulted and circular room more than two metres in 

 diameter. They make there a good pile of very dry 

 hay on which they all install themselves, after having 



o IV - 



