CHAP. H. PROTECTION OF THEIE BURROWS. 65 



according to Hoffmeister, * are the bitterest 

 enemies of worms, or from the larger species 

 of Carabus and Staphylinus which attack them 

 ferociously, for these animals are nocturnal, 

 and the burrows are opened at night. May 

 not worms when the mouth of the burrow is 

 protected be able to remain with safety with 

 their heads close to it, which we know that they 

 like to do, but which costs so many of them 

 their lives ? Or may not the plugs check the 

 free ingress of the lowest stratum of air, when 

 chilled by radiation at night, from the sur- 

 rounding ground and herbage ? I am inclined 

 to believe in this latter view : firstly, because 

 when worms were kept in pots in a room with 

 a fire, in which case cold air could not enter the 

 burrows, they plugged them up in a slovenly 

 manner ; and secondarily, because they often 

 coat the upper part of their burrows with 

 leaves, apparently to prevent their bodies from 

 coming into close contact with the cold damp 

 earth. Mr. E. Parfitt has suggested to me 

 that the mouths of the burrows are closed in 

 order that the air within them may be kept 

 thoroughly damp, and this seems the most 

 probable explanation of the habit. But the 



* ' Familie der Regenwurmer,' p. 19. 



F 



