MOTIONS OF INSECTS. 325 



Derham's system concerning- this motion of animals 

 against gravity. When abroad, he had noticed that a 

 lizard, on account of the sound that it emits before rain, 

 named tjie Gecko '^ (Lacerta Gecko, L.), could walk 

 against gravity up the walls of houses ; and comparing 

 this with the parallel motions of flies, he was desirous 

 of having the subject more scientifically illustrated 

 than it had been. This inquiry was put into the able 

 hands of Sir Everard Home, so justly celebrated as a 

 comparative anatomist, who was assisted in it by the 

 incomparable pencil of Mr. Bauer : and it has been 

 proved most satisfactorily, that it is by producing a va- 

 cuum between certain organs destined for that purpose 

 and the plane of position, sufficient to cause atmo- 

 spheric pressure upon their exterior surface, that the 

 animals in question are enabled to walk up a polished 

 perpendicular, like the glass in our windows and the 

 chunam walls in India, or with their backs downward 



'^ Amoen. /lead. i. 549. The Gecko, probably, is not the only lizard 

 that walks against gravity. St. Pierre mentions one not longer than a 

 finger, that, in the Isle of France, climbs along the walls, and even up 

 the glass after the flies and other insects, for which it watches with great 

 patience. These lizards are sometimes so tame that they will feed out of 

 the hand. — Voyage, &c. 73. Major Moor and Captain Green observed si- 

 milar lizards in India, that ran up the walls and over the cielings after 

 the mosquitos. Hasselquist says that the Gecko is very frequent at 

 Cairo, both in the houses and without them, and that it exhales a very 

 deleterious poison, from the lobuli between the toes. He saw two women 

 and a girl at the point of death, merely from eating a cheese on which it 

 had dropped its venom. One ran over the hand of a man, who endea= 

 voured to catch it; and immediately little pustules, resembling those oc- 

 casioned by the stinging-nettle, Fose all over the parts the creature had 

 touched, — Voyage, 220. 



