THE MOSQUITO 83 



the sloth, ' it passes its Hfe in a state of 

 suspense, like a young curate distantly re- 

 lated to a bishop.' But, since these larvae 

 feed on any kind of organic debris that floats 

 up to the top and is there arrested by the 

 surface-film, it is obviously important that 

 the brushes which sweep together these 

 organic particles and carry them to the 

 mouth should be next the surface, and to 

 effect this the head must rotate through an 

 angle of 180° ; and the head does in fact 

 turn upside-down on the neck so sharply and 

 accurately that, as it comes into position, you 

 almost think, as you are watching it, that you 

 hear a click, just as you do when you rotate the 

 diaphragm of a microscope. 



The mouth parts now begin to vibrate up- 

 wards and forwards, and the brushes are bent 

 downwards, backwards, and inwards. Round 

 the mouth is a small space, the walls of which 

 are completed by the mandibles, and into 

 this space the brushes are suddenly bent 

 back, at the same time the mandibles and 

 maxillae move forward to meet them. This 

 movement may take place as many as 180 

 times a minute, and it produces a current 

 converging in concentric curves towards the 

 above-mentioned chamber. The water filters 

 out between the sides, and any particle of 

 food is retained by the hairs or by the mouth 

 appendages ; from time to time the mandibles 



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