Eyes and other Objects. 75 



The last joint of the spider's foot generally termi- 

 nates in two or three hooks or claws, with comb-like 

 teeth, as you may see in Plate VI., fig. 1. Fig. 2 

 represents them on a larger scale they are shown 

 as "transparent objects/' and for this reason you 

 can see part of the far claw through the centre 

 one. 



This group of claws has been well described as 

 a " sensitive small hand, which twists, and spins, 

 and weaves, and builds nests for its young, and 

 snares for its food/'* It is also observed to be a 

 cleaning instrument. A spider has been seen to 

 spend an hour or more in scraping the delicate 

 threads of its web, when dust or soot had collected 

 on them ; and if they were too thoroughly incrusted, 

 these little claws broke the thread, rolled it up, and 

 threw it away.f 



What a different foot is the fly's ! (Fig. 3.) It 

 is an object almost certain to be found in any micro- 

 scopic collection, however small; and yet there has 

 been considerable uncertainty about the nature of its 

 mechanism. 



Naturalists have always wished to explain how 

 flies can walk up a window, or even upside down on 

 the ceiling of a room ; and there is no doubt that the 

 curious flat appendages at the last joint of the foot 

 enable them to do so. These appendages appear to be 

 of the quality of parchment, and air-tight, and the 



* On the " Feet of Arachnidse." By L. Lane Clarke. " Intellec- 

 tual Observer," April, 1863. 



f See " Objects for the Microscope." By L. Lane Clarke, p. 65. 



