88 DIPTERA. 



supposing the generation of them to proceed 

 in like manner another month, their number 

 will then be more than 700,000, all produced 

 from one couple of flies in the space of three 

 months. " 



The immediate organ of life lies in the tho- 

 rax of the fly, independent of the head. A fly, 

 while in the customary action of rubbing its 

 fore-legs together, and passing them over its 

 headj will not appear at the moment to miss 

 that member, provided it be dexterously cut 

 off at the neck, but will continue the same 

 operation for some turns with its fore-legs, 

 as if nothing had happened. The abdomen 

 may likewise be crushed without killing the fly, 

 but a squeeze on the thorax produces instant 

 death. 



Those phenomena, with which we are quite 

 familiar, are apt to be totally disregarded. No- 

 thing can be more difficult to conceive than an 

 animal, in despite of gravity, running along 

 the ceiling with the same ease as upon the floor; 

 and yet this is daily performed by the fly with 

 the greatest confidence, and daily witnessed by 



