IS't Mr. J. Black wall's Examination of 



escape so as to form one line or more of greater or less tenuity 

 and strength, as may suit their convenience. When suspended 

 by a vertical thread, for example, they frequently suffer another 

 thread to be carried out horizontally, if blown upon in that 

 direction ; but that they have tubes so organized as to enable 

 them forcibly to project their lines to a distance, as M. Virey 

 conjectures, is quite inadmissible. 



The curious fact, that all spiders possessing an apparatus 

 for spinning are not endowed with the instinct to let out their 

 lines when placed on a twig insulated by water and exposed 

 to a current of air, I have proved by numerous experiments: 

 and as this is the case with some of the more common species, 

 as Aranea domestica and Cluhiona atrox^ I take this oppor- 

 tunity of calling the attention of investigators to the circum- 

 stance, which if unnoticed might occasion them some dis- 

 appointment*. 



M. Virey, who has experimented with various species of 

 spiders, and especially with the young of Epeira diadema, in- 

 forms us that " on doit faire ces observations dans une cham- 

 bre close, oii I'air tres calme ne puisse recevoir aucune agita- 

 tion," Being unable to detect the presence of any lines which 

 he considered could contribute to the ascent of these animals, 

 he concludes that the phasnomenon must take place without 

 their concurrence. " Reflechissant," he remarks, " aux moyens 

 par lesquels ces insectes gravissent dans I'air, une seule chose 

 m'a paru la plus vraisemblable, c'est qu'a I'aide des huit pattes 

 que i'animal pent faire vibrer- avec agilite, il nage dans Vair. 

 On conceit que ces membres rapproches, raniant quatre a 

 quatre simultanement de chaque cote, frappent Pair comme des 

 ailes, et peuventfort bien enlever cetinsecte d'ailleurs si leger. 

 Ce procede parait le seul possible dans ce cas. D'ailleurs 

 I'extreme rapidite, ou I'agilite incroyable de ces pattes en tre- 

 pidation, comme la vibration des ailes chez les oiseaux ou les 

 insectes dipteres qui planent dans I'air, font qu'on ne pent 

 pas toujours bien distinguer leur mouvement." And again, " II 

 est done plus probable que ces petites araignees volent avec 

 leurs pattes, que de supposer des effets electriques, ou I'agita- 

 tion de I'air, ce que nous avons demontre faux par I'observa- 

 tion directe." In this bold but fanciful conjecture M. Virey 

 has been anticipated by Dr. Lister, who, in treating upon his 



• It would appear, however, from a notice respecting the habits of 

 Aranea domestica published in the Zoological Journal, vol. i. p. 283, that, 

 under certain circumstances, the instinct in question is manifested by that 

 species of Spider. — Edit. 



*' araneus 



