158 Murrai/s Researches rn Natural History. 



There are but very few spiders, which, in crawling over 

 uneven surfaces, do not leave behind them a thread, serving 

 as a cable, or rather a line of suspension, lest they should fall, 

 or be blown off from any eminence ; consequently, the whole 

 surface of the ground, throughout the summer months, is 

 covered with their network ; not only with webs of the ground 

 spider, which may be called personal property, but from innu- 

 merable threads of vagabonds. This accumulation creates no 

 wonder, because it is certain that these threads, however deli- 

 cate, are at the same time durable. But that this tissue is 

 constantly increasing, may be seen by following the plough 

 for a short space : for no sooner has the team finished one 

 land or ridge, but the fresh ground is quickly interlaced with 

 threads, which glisten in the sunbeam. There is no account- 

 ing for this, except on the facts stated by the author, viz. that 

 the air in fine weather is filled with the excursive threads of 

 the impennous ^ranea aeronautica. The insect is often de- 

 tected at the end of its thread, with its little arms extended, 

 and balancing itself like a bird, and always proceeding before 

 the wind. This direction of their flight always accounted for 

 the connection between tree and tree, or hedge and hedge ; 

 moreover, the insect by its instinctive sagacity, in com- 

 mitting a coil of its thread to the wind, and taking its chance 

 of a distant attachment, could then transport itself in safety. 

 But the author has seen threads projected or propelled in a 

 close room, where there could be no current of air to carry 

 the same in any direct line ; and so far the relation is most 

 interesting. 



Many curious experiments were made by the author, to 

 prove that electricity, either positive or negative, was an agent 

 in the movements of this spider, and the results go far to esta- 

 blish his hypothesis. This opinion, however, is refuted by 

 J. Blackwall, Esq. in Lin, Trans.^ vol. xv. part ii. p. 449. who 

 proves that spiders have no power of propelling their webs, 

 without assistance from the wind ; and that the cobwebs seen 

 floating in the air, are raised from the surface of the ground, 

 by the action of air highly rarefied by a cloudless sun. 



Mr. Murray also thinks that spiders are attracted by musi- 

 cal sounds ; but it is more probable that they descend from 

 ceilings, &c. towards an instrument from an impulse of fear, 

 caused by the vibration of the air, than from any relish for 

 melody. In this section of the book the writer has many per- 

 tinent remarks on the structure and economy of the insect 

 creation ; all showing how important it is to the other branches 

 of animated nature, as affecting vegetation, and even man him- 

 self. Insects can, and actually do, change the features of the 



