268 FOOD OF INSECTS. 



In the above description, which is from my own observations, i have 

 supposed the spider to fix the first and main line of fier net to points from 

 one of which she could readily climb to the other, dragging it after her; 

 and many of these nets are placed in situations where this is very prac- 

 ticable. They are frequently, however, stretched in places where it is 

 quite impossible for the spider thus to convey her main line — between the 

 branches of lofty trees having no connection with each other ; between 

 two distinct and elevated buildings ; and even between plants growing in 

 water. Here then a difficulty occurs. How does the spider contrive to 

 extend her main line, which is often many feet in length, across inacces- 

 sible openings of this description ? 



With the view of deciding this question, to which I could find no very 

 satisfactory answer in books, I made an experiment, for the idea of which 

 I am indebted to a similar one recorded by Mr. Knight^, who informs us 

 that if a spider be placed upon an upright stick having its bottom immersed 

 in water, it will, after trying in vain all other modes of escape, dart out 

 numerous fine threads so light as to float in the air, some one of which 

 attaching itself to a neighboring object, furnishes a bridge for its escape. 

 It was clear that if this mode is pursued by the geometric spiders, it 

 would go considerably towards furnishing a solution of the difficulty in 

 question. I accordingly placed the large diadem spider (Epcira Diadema) 

 upon a stick about a foot long, set upright in a vessel containing water. 

 After fastening its thread (as all spiders do before they move) at the 

 top of the stick, it crept down the side until it felt the water with its 

 fore feet, which seem to serve as antennje: it then immediately swung 

 itself from the stick (which was slightly bent) and climbed up by the 

 thread to the top. This it repeated perhaps a score times, sometimes 

 creeping down a different part of the stick, but more frequently down the 

 very side it had so often traversed in vain. Wearied with this sameness 

 in its operations, I left the room for some hours. On my return I was 

 surprised to find my prisoner escaped, and not a little pleased to discover, 

 on further examination, a thread extended from the top of the stick to a 

 cabinet seven or eight inches distant, which thread had doubtless served 

 as its bridge. Eager to witness the process by which the line was con- 

 structed, I replaced the spider in its former position. After frequently 

 creeping down and mounting up again as before, at length it let itself 

 drop from the top of the stick, not as before by a single thread, but by 

 two, each distant from the other about the twelfth of an inch, guided as 

 usual by one of its hind feet, and one apparently smaller than the other. 

 When it had suffered itself to descend nearly to the surface of the water, 

 it stopped short, and, by some means which I could not distinctly see, 

 broke off close to the spinners the smallest thread, which, still adhering 

 by the other end to the top of the stick, floated in the air, and was so 

 light as to be carried about by the slightest breath. On approaching a 



fined 10 the common garden species alone found iliere, and my attention having been sub- 

 sequently fully occupied in otl.er directions, it did not occur to me that probably the opera- 

 tions of other species might difter from those I had witnessed. These variations, however, 

 do not afl'ect the accuracy of the descnpiion above given of the procedures of the species 

 referred to, one of the commonest of the tribe, which description also, except in the two 

 particulars at)0ve stated, is generally applicable lo the whole geometric race, and has been in 

 great part adojiied by I\lr. Blackwall in his more full detail of their operations. 

 • Treatise on the Apple and Pear, p. 97. 



