220 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



structure which is represented at Fig. 206. It is easy to explain the mode 



of forming this remarkable framework, if we suppose that the spider was 



perched upon the twig, a, and emitted from her spinnerets a 



From thread which was carried out and upward by the wind, and 



Treetop . i j ' 



t P th eiihingled at b, thus forming the prime foundation line, ab. 



Thence she could have moved to the point between d and a, 



whence she would have droj)ped to the ground, a distance of ten feet, 



and hitched a second line to a tuft of grass. A third line might readily 



have been secured by dropping from the point d, the natural swaying 



of the spider, increased by a breeze, carrying her to c. This line, dc, 



could easily have been pulled in by tlie cross lines above and below the 



orb. A convenient frame being thus obtained, the spinning of the orb 



would be a simple mat- 



ter. The entanglement 

 to the side shrubbery at 

 c, c, may also have been 

 made by aid of the 

 breeze in part. 



If, in the absence of 

 direct observation, one 

 were to deny the use 

 of air currents, then it 

 must be supposed that 

 the spider carried its 

 line along the tree to 

 the tip of the branch, b, 

 which was twenty-five 

 feet above the ground ; 

 and after that it would 

 be difficult to conjecture 

 how she could have proceeded. In fact, in this case the " carrjdng around " 

 theory alluded to in a foregoing chapter appears to me quite incredible. 

 If we admit that the moving breeze materially aided the spider in her 

 work of construction, and that she was thus in part dependent upon 

 chance, yet there remains a pretty wide field for intelligent selection and 

 adaptation. One would suppose that it required a really nimble witted 

 creature to seize an unexpected opportunity like the above and turn it to 

 such good account. 



Nor is this an exceptional or even rare example. One often meets, 

 in his walks through our fields and woods, the snares of Orbweavers 

 woven upon the grasses or bushes bordering a meadow path (Fig. 207), 

 or the low undergrowth of an open wood or grove, while the nesting 

 tent and the upper supporting lines arc attached ten or fifteen feet aloft 

 upon a branch or dead limb of a tree. It would be as idle to suppose 



Fig. 208. Trusses on a fractured suare of Agalena noevia. 



