Chap. I. FOOD AND DIGESTION. 39 



into burrows out of doors, at an unknown 

 antecedent period, w T ere tried, and though still 

 moist, they rarely exhibited even a trace of 

 alkaline reaction. 



The fluid, with which the leaves are bathed, 

 acts on them whilst they are fresh or nearly 

 fresh, in a remarkable manner ; for it quickly 

 kills and discolours them. Thus the ends of 

 a fresh carrot-leaf, which had been dragged 

 into a burrow, were found after twelve hours 

 of a dark brown tint. Leaves of celery, 

 turnip, maple, elm, lime, thin leaves of ivy, 

 and occasionally those of the cabbage were 

 similarly acted on. The end of a leaf of 

 Triticum repens, still attached to a growing 

 plant, had been drawn into a burrow, and 

 this part was dark brown and dead, whilst the 

 rest of the leaf was fresh and green. Several 

 leaves of lime and elm removed from burrows 

 out of doors were found affected in different 

 degrees. The first change appears to be that 

 the veins become of a dull reddish-orange. 

 The cells with chlorophyll next lose more or 

 less completely their green colour, and their 

 contents finally become brown. The parts 

 thus affected often appeared almost black by 



