234 FOOD OF INSECTS. 



seven or eight inches distant, which thread had doubtless served as its 

 bridge. Eager to witness the process by which the line was constructed, 

 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 dis- 

 tant 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 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. 1 



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 only one is not so clear. If the position of the main line 

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

 pect 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 accident but de- 

 sign, 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 spider's 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 



1 Some time after making this experiment I stumbled upon a passage in Redi 

 (Z>e Insectis, p. 119.), from which it appears that Blancanus, in his Commentaries 

 upon Aristotle, has related a series of observations which led him to precisely the 

 same result. Lehmann, too, in a paper in the Transactions of the Society of Natu- 

 ralists at Berlin (translated in the Philosophical Magazine, xi. 323.), has given an 

 explanation somewhat similar of the operations of this very spider, but I am in- 

 clined to think erroneous in some particulars. He describes it as emitting numerous 

 floating threads at the commencement of its descent. That he is mistaken in sup- 

 posing these threads to be more than one, is proved by the fact which I have ob- 

 served that 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 ? 



2 An. vii. Vindemiaire. Translated in Phil Mag. ii. 275. 



