Chap. I. WANDER FROM THEIR BURROWS. 15 



plainly marked with their tracks. I have 

 noticed this from August to May, hoth months 

 included, and it probably occurs during the 

 two remaining months of the year when 

 they are wet. On these occasions, very few 

 dead worms could anywhere be seen. On 

 January 31, 1881, after a long-continued 

 and unusually severe frost with much snow, 

 as soon as a thaw set in, the walks were 

 marked with innumerable tracks. On one 

 occasion, five tracks were counted crossing 

 a space of only an inch square. They could 

 sometimes be traced either to or from the 

 mouths of the burrows in the gravel-walks, 

 for distances between 2 or 3 up to 15 yards. 

 I have never seen two tracks leading to the 

 same burrow ; nor is it likely, from what we 

 shall presently see of their sense-organs, that 

 a worm could find its way back to its burrow 

 after having once left it. They apparently 

 leave their burrows on a voyage of discovery, 

 and thus they find new sites to inhabit. 



Morren states * that worms often lie for 

 hours almost motionless close beneath the 

 mouths of their burrows. I have occasionally 

 noticed the same fact with worms kept in 



* ' Di' Lnmbrici terrcstris,' &c., p. 14. 



