THE CYCLE OF LIFE 



453 



promise of the future; the individuals perish, but the 

 race lives on.' 



Gnats. Early in spring we may find the gnats' boat 

 of 300 eggs moored to the water-weed. Early in May 

 the larvae abound in the pools, quaint, dark-coloured 

 creatures, about half an inch long, with slender bristly 

 bodies, and mouth-parts which waft in food-particles. 



FIG. 73. I, Larva. II. Pupa of the Gnat (Culex pipiens). (After Hurst.) 

 BT, respiratory tubes. T, tail end of larva. 



They seem to spend their day between the bottom of the 

 pool and the surface-film, which they perforate with a 

 terminal valved breathing organ at the end of the tail. 

 Hanging head downwards, they accumulate air enough 

 to serve during prolonged submergence. They grow apace 

 and moult three times without changing much in their 

 character. But at the fourth moult a pupa emerges, light- 



