The Cicada: leaving the Burrow 



spaces in between. Thus is an unblocked 

 tunnel obtained, without any refuse, because 

 the dust and rubbish are used on the spot in 

 the form of a mortar which is more com- 

 pact and more homogeneous than the soil 

 traversed. 



The larva therefore works in the midst of 

 clayey mire ; and this is the cause of the stains 

 that astonish us so much when we see it 

 issuing from excessively dry soil. The per- 

 fect insect, though relieved henceforth from 

 all mining labour, does not utterly abandon 

 the use of its bladder; a few drains 

 of urine are preserved as a weapon of de- 

 fence. When too closely observed, it dis- 

 charges a spray at the intruder and quickly 

 flies away. In either form, the Cicada, his 

 dry constitution notwithstanding, proves him- 

 self a skilled irrigator. 



Dropsical though it be, the larva cannot 

 carry sufficient liquid to moisten and turn 

 into compressible mud the long column of 

 earth which has to be tunnelled. The reser- 

 voir becomes exhausted and the supply has 

 to be renewed. How is this done and when? 

 I think I see. 



The few wells which I have laid bare 

 throughout their length, with the pains- 



37 



