124 EVENINGS AT THE MICEOSCOPE. 



CHAPTEE Vn. 



INSECTS : THEtB FEET. 



I HAVE here inclosed a small window-fly in the live- 

 box of the microscope, that you may examine the struc- 

 ture of its feet as it presses them against the glass cover ; 

 and thus not only get a glimpse of an exquisitely-formed 

 structure, but acquire some correct ideas on the ques- 

 tion of how a fly is enabled to defy all the laws of 

 physics, and to walk jauntily about on the under sur- 

 face of polished bodies, such as glass, without falling, or 

 apparently the fear of falling. And a personal examin- 

 ation is the more desirable because of the hasty and er- 

 roneous notions that have been promulgated on the 

 matter, and that are constantly disseminated by a 

 herd of popular compilers, who profess to teach science 

 by gathering up and retailing the opinions of others, 

 often without the slightest knowledge whether what 

 they are reporting is true or false. 



The customary explanation has been that given by 

 Derham in his " Physico-theology ; " that " divers flies 

 and other insects, besides their sharp-hooked nails, have 

 also skinny palms to their feet, to enable them to stick 

 to glass, and other smooth bodies, by means of the pres- 

 sure of the atmosphere, after the manner as I have seen 

 boys carry heavy stones, with only a wet piece of lea- 



