294 



THE MICKOSCOPE. 



rect, as Mr. Blackwell (a gentleman residing in Manchester, and an 

 acute observer of nature) noticed that flies remained attached to the 



fig. 132. Feet and Legs, magnified 150 diameters. 



1. Foot and leg of Ophion. 2. Foot and leg of Blow-fly. 3. Foot and leg of Drone- 

 fly. The small circle encloses each object of about the natural size. 



sides of an exhausted glass receiver of an air-pump, even after they had 

 entirely lost the power of locomotion, and an evident distension of the 

 body had been occasioned by the exhaustion of the air. To detach 

 them from these stations, Mr. Westwood adds, the employment of a 

 small degree of force was found requisite. In prosecuting this subject, 

 clean phials of transparent glass, containing spiders and various insects 

 in the larva and imago (perfect) states, capable of walking on their up- 

 right sides, were breathed into, till the aqueous vapour expelled from 

 the lungs was copiously condensed on their inner surface. The result 

 was remarkable ; the moisture -totally prevented those animals from 

 obtaining any effectual hold on the glass, and the event was equally 

 decisive if a small quantity of oil was substituted for the aqueous 

 vapour. In fact, it was found that powder, or any substance on the 

 inside of the phials, prevented the flies from climbing ; and the idea 

 naturally suggested itself that some glutinous substance was emitted 

 by the feet of the flies, which enabled them to adhere to the glass. 

 The next point to be determined, therefore, was, whether spiders and 



