the SplLr fplns Its Web. 325 



obfervation ha? thrown great licht upon many things relating 

 to the natural hifto-'v of Ijiiders. It points out the principal 

 method which ought to be piirfued in making oblervation.-i 

 on the weather bv means of ihcfc infers, as they conltru6t 

 no new web after deflrojing the old;, wlien impeded by the 

 unfavourable ftate of the weather. This alio enables us to 

 explain why we often obfcrve floating about, during very hot 

 days, prodigious niultif.ides of fpiders webs, commonly 

 known under the name o^ gOjffamer, and which has given oc- 

 cafi.on to fo much difpute among philofophers; for it may 

 be readily conceived, when We reflecl how numerous fpiders 

 are, what a multitude of thefe webs muft be let looie, when 

 they all dellroy their webs at the fame time, in order to con- 

 flruft new ones. During clondv weather none of them are 

 to be feen, for at fuch periods none are let loofe ; and even if 

 there are a few of them in the atmofphere, they acquire hea- 

 vinefs from the moifture they imbibe, of which they are very 

 fufceptibie, and of courfe fall to the earth. I was enabled 

 alfo to determine the difpnte refpc6ting- the organs of vifion 

 in fpiders. Thev undoubtedly have eyes, which are indifpen- 

 fably neceflary for the functions they have to perform, and 

 yet they do not fecm to obferve when a (lick or other dan- 

 gerous weapon is held elofe to thefe organs, but they in- 

 Itantly retreat when in the leaft touched. At prefent, how- 

 ever, this circumltance can be eaiilv explained, for thefe in- 

 fects are noclurnal animals. In the night-time they fpin 

 their webs, and durinti; the morning and evening twilight 

 catch the grealcit number of infe(;:ts. In the night they 



fiaving got up earlier than ufiuil, I f^w the fjiiJer at Jay-break deftroy all 

 the concentric threads proctedinsj from the centre outwards -Aong the ra- 

 dii, breikiiiiT (iff witli iier feet the crofs threads, which (he cemented to 

 the radii (he had left untouched ; and which, by tiiefc means, became pro- 

 grelliv^ly thicker. She did tlie lame witli the principil threads by which 

 the web was made faft ; and which, in coiiletiucnce of the ihrcatis addej 

 to tlicm, were rendered much ftronger. The Imalleft flies or gn;!rs which 

 attempted to enter through the window were therefore cauglit faft in the 

 net ; but towards noon, or (ijmcwhat later, the flies became lliyer, and no 

 more were caught. The fpider therefore about that time retired to a cor- 

 ner wl'.idi (he liad prepared in the window, where ihe laid her egj^s, and 

 where flic remained quiet till the next morning. This oblervaticm Ihows 

 that the tlut.ids of the web lofe their vilcofity by the fun's rays and the 

 heat of the weather; and becoming too dry and hard to be fit for catching 

 thofe infe/.ts on which the fpider feeds, (he is under the iieccUiry of re- 

 newing them. On the other hand, the principal threads, which ferve only 

 for ftrengtheiiiiig the wch, have no need of bejng renewed. Damp wea- 

 ther may perhaps render thefe webs as unfit for catching infecfis as tlic 

 heat does, and therefore the Cpider tliinki it unnectilary to rtiiew licr web 

 a» lon^ us thai teunjerature continues. 



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