342 ARACHNIDA ARANEAE CHAP. 



nerets and float gently to leeward on the light current of air. 



The spider has no power to shoot out a thread of silk to a 

 distance, but it accomplishes the same result 

 indirectly by spinning a little sheet or flocculent 

 mass which is borne away by the breeze. 



When the streaming threads pull with 

 sufficient force the animal casts off, seizes them 

 with its legs, and entrusts itself to the air, 

 whose currents determine the height to which 

 it is carried and the direction of its journey. 

 The duration, however, is not quite beyond the 

 spider's control, at all events in calm weather, 

 for it can furl its sail at will, hauling in the 



FIG 189. Youno- threads " hand-over-hand," and rolling them up 

 Spider preparingfor into a ball with jaws and palps. 



an aerial voyage. nM . . in in-- c 



(After Emerton.) -^ nis curious ballooning habit oi young 



Spiders is independent of the particular family 

 to which they belong, and it is remarkable that newly-hatched 

 Lycosidae and Aviculariidae, whose adult existence is spent 

 entirely on or under the ground, should manifest a disposition 

 to climb any elevated object which is at hand. 



The " Gossamer," which so puzzled our forefathers, is probably 

 no mystery to the reader. It is, of course, entirely the product 

 of Spider industry, though not altogether attributable to the 

 habit of ballooning above described. Only a small proportion of 

 gossamer flakes are found to contain spiders, though minute 

 insects are constantly to be seen entangled in them. They are 

 not formed in the air, as was supposed long after their true 

 origin was known, but the threads emitted by multitudes of 

 spiders in their various spinning operations have been inter- 

 mingled and carried away by light currents of air, and on a still, 

 warm day in spring or autumn, when the newly-hatched spider- 

 broods swarm, the atmosphere is often full of them. 



They rise to great heights, and may be carried to immense 

 distances. Martin Lister relates how he one day ascended to the 

 highest accessible point of York Minster, when the October air 

 teemed with gossamer flakes, and " could thence discern them yet 

 exceeding high " above him. Gilbert White describes a shower, 

 at least eight miles in length, in which " on every side, as the 

 observer turned his eyes, he might behold a continual succession 



