390 INSECT TRANSFORMATIONS. 



mentions ' a very small handsome lizard, about a fin- 

 ger's length, which climbs along the walls, and even 

 along glass, in pursuit of flies and other insects;'* and 

 Sir Joseph Banks noticed another lizard, named the 

 gecko {Lacerta Gecko, Linn.) which could walk 

 against gravity, and which made him desirous of hav- 

 ing the subject thoroughly investigated. On mention- 

 ing it to Sir Everard Home, he and Mr Bauer com- 

 menced a series of researches, by which they proved 

 incontrovertibly, that in climbing upon glass, and walk- 

 ing along the ceilings with the back downwards, a va- 

 cuum is produced by a particular apparatus in the feet, 

 sufficient to cause atmospheric pressure upon their ex- 

 terior surface. 



The apparatus in the feet of the fly consists of two 

 or three membranous suckers connected with the last 

 joint of the foot by a narrow neck, of a funnel shape, 

 immediately under the base of each claw, and moveable 

 in all directions. These suckers are convex above and 

 hollow below the edges, being margined with minute 

 serratures, and the hollow portion covered with down. 

 In order to produce the vacuum and the pressure, these 

 membranes are separated and expanded, and when the 

 fly is about to lift its foot, it brings them together, and 

 folds them up as it were between the two claws. By 

 means of a common microscope, these interesting 

 movements may be observed when a fly is confined in 

 a wine-glass. t 



It is a very remarkable analogy, that many flying 

 insects, as well as many birds, instead of walking, 

 leap or hop along somewhat in the manner of a 

 kangaroo or a jerboa. But the most common and 

 best known instance of a leaping insect, is the flea 

 {Piilex irritans), whose wings are, according to 

 Kirby, obsolescent. The structure of this annoying 



* Voyage to the Isle of France, p. 73. 

 t Philosoph. Trans, for 1816, p. 325. 



