THE METAMORPHOSES OF THE RESPIRATORY SYSTEM. 



49 



apparatus and some short homy tubes, which are often sur- 

 rounded by strong hairs. The tubes are always open at their 

 free ends, and generally project beyond the body of the insect. 

 The common water scorpions are furnished with these structures, 

 and they inspire as well as expire air by means of this curious 



THE LARVA AND NYMPH OF THE GXAT. 

 (The breathing-tube of the larva points upwards, and those of the nymph downwards. } 



respiratory apparatus, without being drowned in their swimming to 

 and fro. The larvae of the Dytiscus, the water beetle, possess these 

 elongated air-breathing tubes, and after metamorphosis the perfect 

 insect, which leads an amphibious sort of life, has the ordinary 

 spiracles for its respiratory purposes, but they are situated on the 



