658 CONSERVATIVE ORGANS. [LECT..XI. 



the disk or flattened knob : others contending 

 that the adhesion is produced by the disk acting 

 like a piece of thick moistened leather at the end 

 of a cord, such as boys employ for lifting stones, 

 which adheres by the external air pressing it 

 closely to the surface on which it is applied : and a 

 third set imagining that it operates by exhausting 

 the air in the same manner as is done by the 

 foot of the fly, and of one species of lizard, 

 which can run up smooth perpendicular walls, 

 and along the ceilings of rooms*. I am dis- 

 posed to set aside all these opinions, and to regard 

 the attachment as the effect of a real radication; 

 having found that the inferior surface or sole of 

 the knob, which terminates each branch of the 

 claw, is studded with minute stellated fibrils ; 

 which entering into the almost invisible pores of 

 stone, bricks, &c. swell, and maintain the claw 

 firmly attached. I am confirmed in this opi- 

 nion, by the fact, that these claws will not ad- 

 here to glass, to Parker's cement, and other very 

 close grained bodies; and that they adhere strongly 

 to stones and other bodies long after the death of 

 the plant. 



Like tendrils these claws turn always from the 

 light ; and, from the experiments of Mr. Knight, 



* For a description of the apparatus necessary for producing 

 this effect in the foot of the lizard, see a paper by Sir Everard 

 Home, Phil. Trans, 



