298 THE MliCHAMCAL FUNCTIONS. 



first joints of the toes (Fig. 153); and all the six 

 feet are provided with these suckers. In the Dy- 

 tiscus, suckers are furnished to the feet of the male 

 insect only. The three first joints of the feet of 

 the fore-legs of that insect have the form of a 

 shield, the under surface of which is covered with 

 suckers having long tubular necks ; there is one of 

 these suckers very large, another of a smaller size, 

 and a great number of others exceedingly small. 

 A few of the latter kind are represented highly 

 magnified in Fig. 154. In the second pair of feet, 

 the corresponding joints are proportionally much 

 narrower, and are covered on their under surface 

 with a multitude of very minute suckers. The 

 Acridium higuttulum, which is a species of grass- 

 hopper, has one large oval sucker, under the last 

 joint of the foot, immediately between the claws. 

 On the under surface of the first joint are three 

 pair of globular cushions, and another pair under 

 the second joint. Fig. 155 shows these parts. 

 The cushions are filled with an elastic fibrous sub- 

 stance ; which, in order to increase the elasticity of 

 the whole structure, is looser in its texture towards 

 the circumference.* 



The mode in which these suckers operate may 

 be distinctly seen, by observing with a magnifying 

 glass the actions of a large blue-bottle fly in the 

 inside of a glass tumbler. A fly will, by the appli- 

 cation of this apparatus, remain suspended from 

 the ceiling for any length of time without the least 

 exertion ; for the weight of the body pulling against 

 the suckers serves but to strengthen their adhesion : 



* Philosophical Transactions for 1826, p. 324. 



