FOOD OF INSECTS. 229 



machinery so complex ? One probable reason is, that it was necessary for 

 drying the gum sufficiently to form a tenacious line, that an extensive sur- 

 face should be exposed to the air, which is admirably effected by dividing 

 it at its exit from the abdomen into such numerous threads. But the chief 

 cause, perhaps, is the occasion (hereafter to be adverted to) which the 

 spider sometimes has to employ its threads in 1 their finer and unconnected 

 state before they unite to form a single one. The spider is gifted by her 

 Creator with the power of closing the orifices of the spinners at pleasure, 

 and can thus, in dropping from a height by her line, stop her progress at 

 any point of her descent; and, according to Lister 1 , she is also able to 

 retract her threads within the abdomen ; but this is doubted, and with 

 apparent reason, by De Geer. 8 



The only other instruments employed by the spider in weaving are her 

 feet, with the claws of which she usually guides, or keeps separated into 

 two or more, the line from behind ; and in many species these are admirably 

 adapted for the purpose, two of them being furnished underneath with teeth 

 like those of a comb, by means of which the threads are kept asunder. 

 But another instrument was wanting. The spider, in ascending the line 

 by which she has dropped herself from an eminence, winds up the superfluous 

 cord into a ball. In performing this the pectinated claws would not have 

 been suitable. She is therefore furnished with a third claw between the 

 other two 3 , and is thus provided for every occasion. 



The situations in which spiders place their nests are as various as their 

 construction. Some prefer the open air, and suspend them in the midst of 

 shrubs or plants most frequented by flies and other small insects, fixing 

 them in a horizontal, a vertical, or an oblique direction. Others select the 

 corners of windows and of rooms, where prey always abounds ; while many 

 establish themselves in stables and neglected out-houses, and even in 

 cellars and desolate places in which one would scarcely expect a fly to be 

 caught in a month. It is with the operations of these last especially that 

 we are accustomed to associate the ideas of neglect and desertion by man 

 associations which, both in painting and allegory, have been often happily 

 applied. Hogarth, when he wished to produce a speaking picture of 

 neglected charity, clothed the poor's box in one of his pieces with a spider's 

 net ; and the Jews, in one of the fables with which they have disfigured 

 the records of Holy Writ, have not less ingeniously availed themselves of 

 the same idea. They relate that the reason why Saul did not discover 

 David and his men in the cave of Adullam 4 was, that God had sent a 

 spider which had quickly woven a web across the entrance of the cave in 

 which they were concealed ; which being observed by Saul, he thought it 

 useless to investigate further a spot bearing such evident proofs of the 

 absence of any human being. 5 



The most incurious observer must have remarked the great difference 

 which exists in the construction of spiders' webs. Those which we most 



1 Hist. Anim. Ang. p. 8. 



2 De Geer, vii. 189. Mr. Blackwall has explained that this apparent retraction 

 which is chiefly perceptible in the line forming the concentric circles of the geo- 

 metric spiders, is an optical illusion, depending upon its extreme elasticity, which 

 admits of its being extended several inches and of contracting again into a minute 

 globule. (Zool. Journ. v. 187.) 



5 Leeuw. Opusc. iii. 317. f. 1. 



* 1 Sam. xxiv. 4. 5 Lesser, 1. ii. 291. 



Q 3 



