112 EVENINGS AT THE MICROSCOPE 



but the very roots, are cut off, as resulting from the 

 weaker vibrations of the contracting muscles, and conse- 

 quently less forcible expulsion of the air when the vibra- 

 tory organs are removed; and he thinks with Chabrier that 

 some air may escape through the open trachece, of the wings 

 which are cut off. Though he regards these laminae as the 

 cause of humming in bees and flies, he does not decide 

 that other causes may not produce the buzz of cockchaf- 

 ers, etc., in the thoracic spiracles of which he could not 

 discern them. 1 



CHAPTER VI 



INSECTS: THEIR BREATHING ORGANS 



IN order to understand the passage last quoted from 

 Burmeister, you ought to know something of the man- 

 ner in which breathing is performed among insects. 

 Essentially, breathing is the same function, wherever it 

 occurs; and it does occur, doubtless, in all animals under 

 some form or other. It is the absorption of oxygen from 

 without to the fluids within, to repair the waste constantly 

 produced by vital energy. But it may be obtained from 

 different sources, and imbibed in various modes. 



All insects in the perfect state are air-breathers; that 

 is, they procure their oxygen from the air as we do; and 

 most of them are so in. their earlier stages. Even in ex- 

 ceptional cases, viz., such larvae or pupae as are provided 

 with what represent gills, and appear to be dependent on 

 the water for their respiration, the exception is rather ap- 

 parent than real, for the function is performed in air- 



1 "Man. of Entom.," 468. 



