ARGONAUT AND GEOMETER. 200 



goini^ to tell us that your spider will introduce air into 

 that cell?" 



"That is precisely what I shall tell 30U. Can you 

 guess how it will be done ?" 



" I have been trying to think ; but I haven't the re- 

 motest notion how the creature could proceed. I can't 

 imagine what implements it possesses for inflating such 

 a structure in such a site." 



"It is done thus : The spider ascends to the surface 

 slowly, assisted by a thread attached to a leaf or other 

 support belon^ and at the surface of the water. When 

 it nears the top it turns, Avitli the extremity of tlic 

 abdomen upward, and exposes a portion of the body to 

 the air for an instant. Then with a jerk it snatches, as 

 it were, a bubble of air, which is attached beneath to 

 the hairs that cover the abdomen, and is held from 

 above by the two liinder legs, which are crossed at an 

 acute angle near their extremity. This crossing of the 

 legs occurs at the instant the bubble is seized. The 

 little creature then descends more rapidly than it 

 mounted, regains its cell, always by the same route, 

 turns the abdomen within the mouth, and disengages 

 the bubble. This is repeated many times until the 

 sac is filled and rounded out Avith air. This cell serves 

 the water spider as living-room, dining-room and nur- 

 sery. Here she spins her saucer-shaped cocoon, fixing 

 it against the inner side of the cell near the top. Out 

 of it, by and by, issue a hundred spiderlings, who spend 

 their babyhood in this ingenious home, literally 

 ' Rocked in the cradle of the deep.' 



