M. Virey's Observations on Aeronautic Spiders. 181 



very reverse of tliose advanced in my paper. Of the great 

 injustice done to me in that article I have every reason to 

 complain, were I disposed to give way to personal feelings; 

 my sole object, however, in animadverting upon it is the pro- 

 motion of science, being impressed with the belief that the 

 principal errors into which M. Virey has fallen, if suffered to 

 remain unnoticed, must tend to retard its progress. That I 

 should be thus forced into collision with a distinguished fel- 

 low-labourer in the field of natural history, I sincerely regret. 

 As it would be tedious to enter into a minute consideration 

 of the various misconceptions on the part of M. Virey, ad- 

 verted to above, I shall particularize such only as directly mili- 

 tate against the theory I have endeavoured to establish re- 

 lative to the ascent of aeronautic spiders in the atmosphere. 



In narrating the fact observed by me in October 1826, — 

 namely, that the tissues usually denominated gossamer-webs 

 are formed at the surface of the earth, and are afterwards 

 raised into the atmosphere by ascending currents occasioned 

 by the rarefaction of the air contiguous to the ground when 

 heated by the sun in serene weather, — M. Virey states that I 

 witnessed the ascent of webs more than a hundred feet long, 

 ("des trainees de plus de cent pieds de long de ces toiles,") 

 and that I investigated the process employed by the spiders 

 in fabricating " ces subtils calicots" as he facetiously terms 

 them, in reference to the manufacturing district where my 

 researches wei"e made, " pour s'elever dans I'atmosphere et 

 franchir au loin les espaces." Now, so far from ascribing the 

 construction of these webs to spiders, in the instance referred 

 to, I attribute their formation to the adhesion of the slender 

 filaments of which they are composed on being brought into 

 contact by the mechanical action of gentle airs. That the 

 filaments are produced by spiders I am perfectly well aware, 

 but 1 have no where asserted that these animals convert them 

 into the webs termed gossamer; neither have I affirmed that 

 they employ such webs to effect their aerial excursions, as 

 M. Virey intimates: on the contrary, the accomplishment of 

 their purpose is shown by me to depend upon ascending cur- 

 rents of rarefied air impingeing against the fine lines emitted 

 from their spinners, which generally remain distinct through- 

 out their entire length. The occurrence of spiders upon 

 gossamer-webs I represent to be entirely accidental ; and that 

 the former are instrumental in promoting the ascent of the 

 latler I positively deny : yet M. Virey professes to say on my 

 authority, that the animals aspire " a les faire envoler, en les 

 fixant legeremcnt a rextremite d'un corps en pointe." My 

 account of the height to which I have seen these webs raised 



in 



