MOTIONS OF INSECTS. 325 
History becomes daily more indebted, has lately excited 
an inquiry, the results of which have confirmed 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 the Gecko? 
(Lacerta Gecko, L.), could walk against gravity up the 
walls of houses; and comparing this with the parallel mo- 
tions 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 vacuum between certain organs destined for 
that purpose and the plane of position, sufficient to 
cause atmospheric pressure upon their exterior surface, 
that the animals in question are enabled to walk up a 
2 Amen. Acad. 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 similar lizards in India, 
that ran up the walls and over the ceilings 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 anda 
girl at the point of death, merely from eating a cheese on which it 
had dropped its venom. One ran over the hand of aman, who 
endeavoured to catch it; and immediately little pustules, resembling 
those occasioned by the stinging-nettle, rose all over the parts the 
creature had touched.—Voyage, 220. M. Savigny, however, who 
examined this animal in Egypt, assures me that this account of 
Hasselquist’s, as far as it relates to the venom of the Gecko, is nos 
correct, 
