FOOD OF INSECTS. 269 



pencil to the loose end of this line, it did not adhere from mere contact. 

 I therefore twisted it once or twice round the pencil, and then drew it 

 tight. The spider, which had previously climbed to the top of the stick, 

 immediately pulled at it with one of its feet, and, finding it sufficiently 

 tense, crept along it, strengthening it as it proceeded by another thread, 

 and thus reached the pencil.^ 



That this therefore is one mode by which the geometric spiders convey 

 the main line of their nets between distant objects, there can be no doubt, 

 but that it is the onli/ one is not so clear. If the position of the main 

 line be thus determined by the accidental influence of the wind, we might 

 expect to see these nets arranged with great irregularity, and crossing 

 each other in every direction ; yet it is the fact, that however closely 

 crowded they may be, they constantly appear to be placed not by acci- 

 dent but design, commonly running parallel with each other at right angles 

 with the points of support, and never interfering. Another objection too 

 presents itself. From the experiment related, it is clear that the main line 

 of the net can never be longer than the height of the object from which 

 the spider dropped in forming it. But it is no uncommon thing to see nets 

 in which these lines are a yard or two long fastened to twigs of grass not 

 a foot in height, and yet separated by obstacles effectually precluding the 

 possibility of the spiders having dragged the lines from one to the other. 

 Here, therefore, some other process must have been used. 



Both these difficulties would be removed by adopting the explanation 

 of an anonymous author in the Journal de Physique^ founded, as he 

 asserts, on actual observation. He says that he saw a small spider, which 

 he had forced to suspend itself by its thread from the point of a feather, 

 shoot out obliquely in opposite directions other smaller threads, which 

 attached themselves in the still air of a room, without any influence of the 

 wind, to the objects towards which they were directed. He, therefore, 

 infers that spiders have the power of shooting out threads and directing 

 them at pleasure towards a determined point, judging of the distance and 

 position of the object by some sense of which we are ignorant. Something 

 like this manoeuvre I once myself witnessed in a male of the small garden 

 spider (Epeira 1 reticulata). It was standing midway on a long perpendicu- 

 lar fixed thread, and an appearance caught my eye of what seemed to be the 

 emission of threads from its projected spinners. I therefore moved my 

 arm in the direction in which they apparently proceeded, and, as I sus- 

 pected, a floating thread attached itself to my coat, along which the 

 spider crept. As this was connected with the spinners of the spider, it 

 could not have been formed in the same way with the secondary thread of 

 E. Diadema above described. 



' Sometime after making this experiment I stumbled upon a passage in ReJi (De Inseciis, 

 p. 119.), from which it appears that Blancanus, in his Commentaries upon Aristotle, has 

 related a series of observations which led him to precisely ihe same result. Lehmann, too, 

 in a paper in the Transactions of the Society of Naturalists at Berlin (translated in the Phi- 

 losophical Magazine, xi. 32o.) has given an explanation somewhat similar of the operations 

 of this very spider, but I am inclined to think erroneous in some particulars. He describes 

 it as emitting numerous floating threads at the commencement of its descent. That he is mis- 

 taken in supposing these threads to be more than one, is proved by the fact which I have 

 observed — thai even that one sometimes breaks by the weight of the spider. How then 

 could an insect almost as big as a gooseberry be supported by a line of the tenuity here 

 attributed to it ? 



* An. vii, Vindimiaire. Translated in Fhil. Mag. ii. 275. 



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