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XXVII. Remarks on the Pulvilli of Insects. By John Black- 

 wall, Esq., F.L.S. 



Read, February 1, 1831. 



In the Physico-Theology of Dr. Derham, p. 363, note b, it is 

 stated that " diverse Flies, and other Insects, besides their sharp 

 hook'd Nails, have also skinny Palms to their Feet, to enable 

 them to stick on Glass, and other smooth Bodies, by means of 

 the Pressure of the Atmosphere." This opinion, which appears 

 to be almost universally adopted by the entomologists of the 

 present day, has derived additional weight from the investiga- 

 tions of Sir Everard Home, whose papers relative to this curious 

 subject, illustrated by figures of the parts employed in climbing, 

 engraved principally from drawings made by Mr. Bauer, are 

 published in the Transactions of the Royal Society for 1816. 

 These researches are regarded by Messrs. Kirby and Spence 

 (see their Introduction to Entomology, vol. ii,. Letter xxiii.) as 

 having " 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 the exterior surface, that the animals in question are en- 

 abled to walk up a polished perpendicular, like the glass in our 

 windows, or with their backs downward on a ceiling, without 

 being brought to the ground by the weight of their bodies." To 

 dissent from a theory so generally received, including among its 

 advocates numerous illustrious names, may, perhaps, be deemed 

 VOL. XVI. 3r presumptuous; 



