FOOD OF INSECTS. 233 



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

 supposed the spider to fix the first and main line of her 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 inaccessible 

 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 1 , 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 neighbouring 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 (Epeira 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 antennas : 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 ope- 

 rations, 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 



or other shelter, and there construct a cell in which the spider remains concealed 

 till the vibrations of a strong line of communication, composed of several united 

 threads, which she has spun from the centre of the net to her cell, inform her of the 

 capture of a fly, to which she then rushes along this bridge. This criticism as to 

 the too extensive generalisation of the procedures of the garden spider above de- 

 scribed is perfectly just, as my own observations since the publication of the last 

 edition of this work, but long before I had seen Mr. Blackwall's paper, had shown 

 me. My excuse must be that the observations above recorded (which are left pre- 

 cisely as originally written about the year 1812), having been made on the spur of 

 the occasion in my garden at Drypool, near Hull, when to my surprise I could not 

 find in books any intelligible account of the way in which the geometric spiders 

 construct their nets, were necessarily confined to the common garden species alone 

 found there, and my attention having been subsequently fully occupied in other 

 directions, it did not occur to me that probably the operations of other species might 

 differ from those 1 had witnessed. These variations, however, do not affect the 

 accuracy of the description above given of the procedures of the species referred to, 

 one of the commonest of the tribe, which description also, except in the two parti- 

 culars above stated, is generally applicable to the whole geometric race, and has 

 been in great part adopted by Mr. Blackwall in his more full detail of their 

 operations. 



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



