212 ANIMAL INTELLIGENCE. 



The position must also offer favourable opposite points for the 

 attachment of the web itself. People have often puzzled their 

 brains, wondering how spiders, without being able to fly, had 

 managed first to stretch their web through the air between two 

 opposite points. But the little creature succeeds in accomplish- 

 ing this difficult task in the most various and ingenious ways, 

 It either, when the distance is not too great, throws a moist 

 viscid pellet, joined to a thread, which will stick where it 

 touches ', or hangs itself by a thread in the air and lets itself be 

 driven by the wind to the spot ; or crawls there, letting out a 

 thread as it goes, and then pulls it taut when arrived at the 

 desired place; or floats a number of threads in the air and 

 waits till the wind has thrown them here or there. The main 

 or radial threads which fasten the web possess such a high 

 degree of elasticity, that they tighten themselves between two 

 distant points to which the spider has crawled, without it being 

 necessary for the latter to pull them towards itself. When the 

 little artist has once got a single thread at its disposition, it 

 strengthens this until it is sufficiently strong for it to run back- 

 wards and forwards thereupon, and to spin therefrom the web. 1 



Special Habits. 



Water-spider. The water-spider (Argyroneta aqua- 

 tica\ as is well known, displays the curious instinct of 

 building her nest below the surface of water, and construct- 

 ing it on the principle of a diving-bell. The animal 

 usually selects still waters for this purpose, and makes 

 her nest in the form of an oval hollow, lined with web, 

 and held secure by a number of threads passing in various 

 directions and fastened to the surrounding plants. In 

 this oval bell, which is open below, she watches for prey, 

 and, according to Kirby, 2 passes the winter after having 

 closed the opening. The air needful for respiration the 

 spider carries from the surface of the water. To do this 

 she swims upon her back in order to entangle an air- 

 bubble upon the hairy surface of her abdomen. With this 

 bubble she descends, < like a globe of quicksilver,' to the 

 opening of her nest, where she liberates it and returns for 

 more. 



1 IMC. cit., p. 316 et seq. 



z Hist. Habits a-nd Inst, of Animals, vol. ii... p. 296. 



