INSECTS : THEIR MOUTHS. 151 



until at length it forms a double line, being folded on 

 itself, so that the base is brought into close proximity to 

 the skin. Meanwhile the lancets have all been plunged 

 in, and are now sunk into your flesh to their very bottom, 

 while the labium, which formed merely the sheath for the 

 whole, is bent up upon itself, ready again to assume its 

 straight form, as soon as the disengaged lancets require its 

 protection. 



TONGUE OP BLOW-FLY. 



The tongue of one of the common Flies (House-fly, 

 Blow-fly, &c), is an exquisite microscopical object, from 

 its extreme complexity and beauty. You are familiar with 

 the way in which a fly, having alighted close to a drop of 

 tea on the table, applies to it a proboscis with large 

 dilated extremity, and presently licks it all up. You shall 

 now see the curious implement by which this is effected. 



