238 HOUSE, GARDEN, AND FIELD 



the air, enables her to pass to a point which would be 

 entirely inaccessible otherwise. 



The garden spider is guided in these operations entirely 

 by her sense of touch. Blackwall tells us that he repeatedly 

 confined garden spiders in glass jars placed in absolute 

 darkness, and found that though unable to see they made 

 nets of admirable workmanship. 



What kind of feet does a spider require in order to run 

 about on a network of fine silken threads ? It is worth 

 while to examine the foot of the garden spider or any 

 other. You will find a pair of strong claws projecting 

 from the upper surface of the last joint. Each claw is 

 curved, and armed beneath with a row of teeth. A third 

 and smaller claw is found beneath the pair, and on close 

 examination several more claws, each with a row of 

 pointed teeth, can be made out. We see that the comb- 

 like teeth are suitable for clutching at a fine thread, but 

 the difficulty is to explain why so many claws are required. 

 On the hind legs, and on them only, are opposable claws, 

 which can grasp the thread as well as hook on to it. When 

 the spider dangles from its thread, it always holds on 

 by the opposable claws of its hind feet. The harvestman 

 makes no web, but follows its prey over stubble and the 

 slender blades of grass. Here you will find that the foot 

 consists of a long series of minute joints, each with its own 

 set of outstanding hairs ; the whole series may be half 

 as long as the rest of the leg. The extraordinary length 

 and flexibility of such a foot are obviously adapted to 

 support on a yielding surface. The harvestman, one 

 might almost say, runs about on flexible snow-shoes 

 (see p. 114). 



The silk of the garden spider is employed by opticians 

 in one of the most delicate parts of their work, namely, 

 the quartering of the field of a telescope or theodolite. 

 The garden spider, which is easily identified by the white 

 cross on its back, is always selected. When captured 

 and set on a wire fork, she attaches her thread and lets 



