M. Virey's Observations on Aeronautic Spiders. 183 



lines to a distance. On what grounds this assumption, so 

 contrary to the whole tenour of my experience, is founded, I 

 have yet to learn. 



I shall now proceed to examine the observations on the 

 ascent of spiders communicated by M. Virey to the French 

 Institute in June 1829, and published in the Bulletin des 

 Sciefices Naturelles for October in the same year, p. 130-134< ; 

 availing myself of the opportunity thus afforded, to introduce 

 several interesting particulars which have recently come to 

 my knowledge. Having already rendered it sufficiently ap- 

 parent that M. Virey does not comprehend my views relating 

 to the ascent of gossamer-webs and spiders, any notice of the 

 allusion made to them in the present article is unnecessary ; 

 I pass on therefore to the author's remarks on the power 

 which he supposes spiders to possess of darting out their lines 

 to a distance. " Je m'etois assure deja," he writes, " que 

 jusqu'a la distance de deux pieds environ, une araignee savait 

 iancer prestement un fil vers un point quelconque, I'y attacher, 

 et s'enfuir soudain sur cette corde. II faut que dans le nombre 

 de leurs filieres elles aient des tubes ejaculateurs, puisqu'elles 

 lancent ces fils independamment d'autres sur lesquels elles 

 s'avancent, et qu' elles emettent en meme temps." This opi- 

 nion, which has been entertained by so many eminent natura- 

 lists, may be refuted without difficulty. If spiders be placed 

 on a twig fixed upright in a glazed earthen vessel with per- 

 pendicular sides, containing a sufficient quantity of water com- 

 pletely to encompass its base, they will be found totally inca- 

 pable of escaping from their place of confinement in a still 

 atmosphere; but when exposed to a current of air, or when 

 blown upon with the breath, the case is otherwise, as many 

 species may then be perceived to emit from their spinners a 

 little of their viscous secretion, which being carried out in a 

 line by the agitated air, becomes attached to some object in 

 the vicinity, and affords them the means of regaining their 

 liberty. 



These facts were first established by me in 1826, in the 

 manner here described ; and in the summers of 1828 and 1829 

 I repeated the experiment with about thirty distinct species of 

 spiders under every variety of circumstances which appeared 

 likely to influence the result. My former conclusions, how- 

 ever, were most unp(|uivocally confirmed, and I am confident 

 in asserting that these animals have not the power of darting 

 their lines even through the space of half an inch. 



It is certain that spiders can open and close the orifices of 

 their spiiuiers at pleasure, and can allow their liquid gum to 



escape 



