70 



MECHANICAL FUNCTIONS. 



Doubts concerning this mechanism. Notwithstanding 

 it would thus appear, that there could be no doubt with 

 respect to the manner in which Flies are enabled to ad- 

 here to smooth surfaces, yet some entomologists still 

 doubt whether the feet of these Insects really contain 

 any organs which adhere by suction. If Flies adhere 

 by the pressure of the atmosphere, then, if the atmos- 

 phere be removed, it is said, they would be unable to 

 walk on a smooth perpendicular surface. To demon- 

 strate this, house Flies were put into the glass receiver 

 of an air-pump, and the air exhausted, when it is said, 

 " it was demonstrated to the entire satisfaction of several 

 intelligent gentlemen present, that the house Fly, while 

 it retains its vital powers unimpaired, can, not only trav- 

 erse the upright sides, but even the interior of the dome 

 of an exhausted receiver, and that the cause of its re- 

 laxing its hold, and ultimately falling from the station it 

 occupied, was a diminution of muscular force, attributa- 

 ble to impeded respiration." In consequence of such 

 experiments, it has been proposed to account for the 

 phenomena observed, by the secretion of an adhesive 

 matter with which the foot of the Fly, or the hairs on it 

 are embued. The advocates for this mode say, that 

 they have facts on this subject, which are quite inexpli- 

 cable except on the supposition that an adhesive secretion 

 is emitted by the instruments employed in climbing. 

 We are however, rather inclined to the belief that these 

 Insects adhere by the pressure of the atmosphere as 

 was so clearly shown by the observations of Sir E. 

 Home. 



INGENUITY OF INSECTS. 



There are some traits in the characters and habits of 

 certain Insects, which appear so much like the cunning, 

 ingenuity and contrivance of the higher order of ani- 

 mals, that we cannot see why they have not an equal 



What experiment seems to make it doubtful whether flies adhere by 

 the pressure of the atmosphere 1 ^yhat is the conclusion of the author 

 with respect to the means by which flies adhere to smooth surfaces 1 

 What is meant by the ingenuity of insects 7 



