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VIEWS OF THE MICROSCOPIC WORLD. 

 Fig. 219. Fig. 220. 



Fig. 221. 



Fig. 222. 



joints, as in figure 220. In a species of water-beetle, the male insect is alone 

 provided with a numerous collection of suckers. The first three joints of the 

 feet of the fore-legs, have the form of a shield, the under surface of which 

 is covered with suckers, some very large, others small, and a third class exceed- 

 ingly minute, all provided with long, hollow stems. Several of the smallest kind 

 are exhibited in figure 221, highly magnified, and having the appearance of mush- 

 rooms with the cups inverted. The corresponding joints of the second pair of 

 feet, are likewise studded on the under side with a vast number of minute ap- 

 pendages of this character. 



A certain species of grasshopper, called the Acridium biguttulum, is fur- 

 nished with a large oval sucker, which is placed between the claws beneath the 

 last joint of the foot. The first joint is padded on the lower side with three pairs, 

 and the second with one pair of cushions. These cushions are filled with an elastic 

 fibrous substance, the texture of which is looser towards the margin, in order to 

 increase the elasticity. The several parts are displayed in figure 222. By the 

 aid of this singular apparatus, insects are enabled to traverse with the greatest 

 facility the smoothest surfaces, in an inclined, vertical, or inverted position. 

 Thus a fly is seen to walk upon a mirror, a ceiling, or the under surface of a pane 

 of glass, with as much ease and security as upon the top of a table. Indeed, 

 when inverted, the weight of the fly causes the sucker to adhere more firmly 

 than in any other position ; inasmuch as the weight of the insect tends to draw 

 down the sucker and to increase the vacuum beneath it, and thus to render the pres- 

 sure of the atmosphere upon the sucker proportionally greater. To this fact .has 

 been attributed the circumstance, that flies congregate upon the ceiling and re- 

 pose there during the night, since the pressure of the air upon the membrane of 

 the suckers fixes them firmly in their resting-place, without any voluntary effort. 



ANTENNAE. This name is given to certain curious organs possessed by insects 

 and crustaceous animals ; the majority of the latter class being endowed with four, 

 while no insect has more than one pair. They are inserted in the head, and, ex- 

 cept where the insect has four eyes, are either placed in the space between the 

 eyes, or in that immediately beneath them. They are, for the most part, formed 



