350 THE BOOK OF A NATURALIST 



down in this dark dead soil the worms will insist 

 on descending, although their only way to it is 

 through the few small cylindrical holes they have 

 succeeded in boring through the partially rotted 

 cement between the tiles, or where a minute stone 

 has dropped out of the tesserae pavements. Their 

 descent into these difficult places and down into 

 the old pits involves long double journeys daily 

 when they are forced to come up to deposit their 

 castings on the surface. 



What then is the force impelling them ? Why 

 do they leave a rich feeding-ground for a poor one ? 

 I take these facts in their relation to other well- 

 known facts, as for example that of the quite 

 extraordinary difference in size and vigour and 

 colouring in the earthworms inhabiting different 

 soils. They are like different species. Let us take 

 the case of the London earthworm to be found in 

 every few square yards of earth unbuilt on, even 

 in the very heart of the City itself. Judging from 

 all the specimens I have examined, this worm 

 attains to about half the full normal size and is 

 comparatively languid in his movements and rarely 

 exhibits the brilliant play of colours seen in the 

 large country worm in rich soil — the colour which 

 is the sign of intensity of life. Doubtless he was 

 once a big vigorous worm, but that was long ago 

 in an old London, or Londineum, and he has had 

 ample time to degenerate. In this state he is now 

 biding his time, under our feet, and his time will 

 come when our seven millions have faded or 



