188 



LIFE, IN ITS INTERMEDIATE FORMS. 



powers to a curious purpose. It forms a residence beneath 

 the surface of water, which, like our diving-bells, is filled 

 with air. It is commonly said that she first spins loose 

 threads, connecting the stems of water-plants, among 

 which she weaves a little cell, which she then manages to 

 fill with air successively carried down in bubbles from the 

 surface, in some unknown manner. But Baron Walcke- 

 naer, who writes from personal observation, describes the 

 process differently. The abdomen is covered with a close 

 down, which does not permit the water to wet the skin ; 

 when beneath the surface the whole .body is enveloped in 

 a coat of air, so that it resembles a ball of quicksilver. 



" When the Argyroneta would construct its nest, it 

 swims to the surface, 

 and, head downward, pro- 

 trudes the extremity of 

 the abdomen, dilating its 

 spinnerets, and then 

 dives with rapidity. By 

 this process she produces \ 

 a little bubble of air, I 

 w T hich, independent of 

 the silvery coating which 

 envelopes the body, ap- 

 pears as a little globule 

 attached to the tail. She 

 swims to the stalk of 

 the plant to w T hich she 



would fix her nest, and, The Water-Spider. 



touching it with the bubble, the air detaches itself and 

 adheres to the plant. The Spider then remounts to the 



