( 40 ) 



with tiie pencil, but tliat by an engraving, it nii^lit in fi)nie nieafiii-o 

 be rcprefented. This is done in ^"^.20, MNOFQ, being a portion 

 of thcl'c threads, as magni' ed by the microfcopc, and pichired fepa- 

 rate and diliini:t from each other, as they iflued from the body of the 

 iininud. Thefe feemed to me to ifliie from two of tlic organs, which 

 I fliall prefently defcribe. 



If v,e dniy confider tliat the threads of Spiders, whicli to the 

 naked eye feem to be lingle, are compofed of maoy fmaller ones, 

 and tb.at they thence acquire the flrcngtli we obferve tlicm to have, 

 we fliall more than ever be afi'ured, tliat no flexible bodies (exce])t 

 thofe made of metal, the component particles of which are, by the 

 force of fire, molt clofely compacted or knit together), can have 

 any great (trength or toughnels, iinlefs they are compofed of ob- 

 long parts laid fide by fide, and that their ftrength or toughnefs will 

 be greater where thefe oblong coinponent parts are twilled together, 

 or made to cohere by fome glutinous matter, as are fpun filk, linen 

 garments, ropes and the like. And this is the reafcn why all tlie 

 fing'e threads of flax are very tough in proportion to their fize, for 

 each of them is compofed of dill fmaller particles or fibres, which are 

 not only joined together by a certain viicous or gunnny matter, but 

 are alfo furrounded with a coat or bark, as it may be called, whereby 

 their inward component fibres are rendered ftill ftronger 



Again, if we advert to the great number of excefi[ively flender 

 threads, proceeding, all at the fame time from the bod}' of the Spider, 

 we muft acknowledge that this kind of formatioii is neceflary, for 

 were it a fingle thread which is fpun by this creature with liich ce- 

 lerity, the hquid matter of which it is formed, could not on its expc- 

 fure to the air, become a iblid fubfiance fo quickly as thefe lefl'er 

 threads ; an hundred or more of which, taken together, do not in my 

 opinion equal the hundredth part of one of thofe hairs I can take 

 from the back of my hand. 



