368 Insect Architecture. 



wonderful apparatus is represented as it appears in the 

 microscope. 



We do not recollect that naturalists have ventured to assign 

 any cause for this very remarkable multiplicity of the 

 spinnerules of spiders, so different from the simple spinneret 

 of caterpillars. To us it appears to be an admirable provision 

 for their mode of life. Caterpillars neither require such 

 strong materials, nor that their thread should dry as quickly. 

 It is well known in our manufactures, particularly in rope- 

 spinning, that in cords of equal thickness, those which are 

 composed of many smaller ones united are greatly stronger 

 than those which are spun at once. In the instance of the 



Spinnerets of a Spider magnified to show the Spinnerules. 



spider's thread, this principle must hold still more strikingly, 

 inasmuch as it is composed of fluid materials that require to 

 be dried rapidly, and this drying must be greatly facilitated 

 by exposing so many to the air separately before their union, 

 which is effected at the distance of about a tenth of an inch 

 from the spinnerets. In the following figure each of the 

 threads represented is reckoned to contain one hundred 

 minute threads, the whole forming only one of the spider's 

 common threads. 



Leeuwenhoeck, in one of his extraordinary microscopical 

 observations on a young spider not bigger than a grain of 

 sand, upon enumerating the threadlets in one of its threads, 



