Chap. IL THEIR INTELLIGENCE. 71 



proportion of the laburnum leaves not hav- 

 ing been drawn in by the base, by worms 

 having acquired the habit of generally drawing 

 in leaves by their tips and thus avoiding the 

 foot-stalk. For the basal margin of the blade 

 in many kinds of leaves forms a large angle 

 with the foot-stalk ; and if such a leaf were 

 drawn in by the foot-stalk, the basal margin 

 would come abruptly into contact with the 

 ground on each side of the burrow, and would 

 render the drawing in of the leaf very difficult. 

 Nevertheless worms break through their 

 habit of avoiding the foot-stalk, if this part 

 offers them the most convenient means for 

 drawing leaves into their burrows. The leaves 

 of the endless hybridised varieties of the 

 Rhododendron vary much in shape ; some are 

 narrowest towards the base and others to- 

 wards the apex. After they have fallen off, 

 the blade on each side of the midrib often 

 becomes curled up while drying, sometimes 

 along the whole length, sometimes chiefly 

 at the base, sometimes towards the apex. 

 Out of 28 fallen leaves on one bed of peat in 

 my garden, no less than 23 were narrower in 

 the basal quarter than in the terminal quarter 

 of their length; and this narrowness was 



