196 THE WONDERS OF INSTINCT 



know? Certainly not by sight. Before recognizing 

 their mistake, they have to hold the object between their 

 legs and even to nibble at it a little. They are extremely 

 short-sighted. At a hand's-breadth's distance, the lifeless 

 prey, unable to shake the web, remains imperceived. 

 Besides, in many cases, the hunting takes place in the 

 dense darkness of the night, when sight, even if it were 

 good, w^ould not avail. 



If the eyes are insufficient guides, even close at hand, 

 how will it be when the prey has to be spied from afar? 

 In that case, an intelligence apparatus for long-distance 

 work becomes indispensable. We have no difficulty in 

 detecting the apparatus. 



Let us look attentively behind the web of any Epeira 

 with a daytime hiding-place: we shall see a thread that 

 starts from the center of the network, ascends in a slant- 

 ing line outside the plane of the web and ends at the 

 ambush where the Spider lurks all day. Except at the 

 central point, there is no connection between this thread 

 and the rest of the work, no interweaving with the 

 scaffolding-threads. Free of impediment, the line runs 

 straight from the center of the net to the ambush-tent. 

 Its length averages twenty-two inches. The Angular 

 Epeira, settled high up in the trees, has shown me some 

 as long as eight or nine feet. 



There is no doubt that this slanting line is a foot- 

 bridge which allows the Spider to repair hurriedly to the 

 web, when summoned by urgent business, and then, 

 when her round is finished, to return to her hut. In 

 fact, it is the road which I see her follow, in going and 



