102 THE LIFE OF AN INSECT. 



over-fatigue one leg, for on its return the leg 

 previously in use is at rest, while the one on the 

 opposite side is now called into duty. The insect 

 thus works on until its trap is completely exca- 

 vated, the task occupying a variable time ; some- 

 times being finished in half an hour, sometimes 

 even in less, but occasionally occupying several 

 hours, the little labourer being obliged to rest a 

 certain time. Reaumur, who has given a fasci- 

 nating account of these insects, writes, u I have 

 had at times hundreds of ant-lions in a large box, 

 and I have often been amused with filling up their 

 traps. Some of them would immediately begin 

 to form another; but the greater number in the 

 warm long days of summer deferred executing the 

 work until the sun began to go down. They 

 seldom worked in the heat of the day ; but in cold 

 or cloudy weather they would excavate at any 

 hour." 



We well know what perplexity a chain of rocky 

 hills causes to a railroad engineer, and what vast 

 outlays of money, labour, and time are necessary 

 in order to overcome the obstacle thus presented 

 to the path of the engine and its train. But it 

 may be safely said that we can furnish a parallel in- 



