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thi.<5, can refrain from exclaiming with me " How infcrutable and 

 incomprelienfible are the hidden works of Nature \" 



The filken cafe or web of which I am now treating, and which the 

 indiiflry and ingenuity of mankind has converted to fo many ufeful 

 purpofes, is conftru6led by the animal for no other end than that, 

 when its change into a cliryfalis or aurelia approaches, and it cannot 

 then be concealed under the leaves of the trees, nor can during the 

 time of its change adhere to any thing, nor even change its place, and 

 during all that time lies as it were motionlefs, it may be preferved 

 from becoming a prey to birds ; and this I am well convinced is the 

 cafe with all infe^ls of the caterpillar kind, which, when they are full 

 grown, and their change approaches, wrap themlelves in fome kind of 

 web or covering. 



But my chief objeft, in all thefe my obfervations, was, to difcover 

 as much as poflible the nature of that organ from whicli thefe two 

 threads proceed, and by what contrivance they are joined ib clofcly 

 together : the common opinion refpe6ling whicli threads is, tliat they 

 ifliie from the animal's mouth. For this purpol'e I found it necefiary 

 to fix a Silk-worm on its back, and then the organ, which is placed 

 below the mouth, appeared in fight. Fig. ^o, ABC, exhibits this 

 organ. The parts marked DE and FG are placed below the mouth, 

 and the organ from which the threads ifliie is fituated ftill lower. 

 While the limner was making this drawing, fome part of the teeth 

 appeared in his view, which he alfo included in the figure, at the 

 letters HI K, and this was done, more clearly to prove, that the 

 threads do not proceed out of the Silk- worm's mouth, as is the vul- 

 gar opinion. 



After I had dil'covered the particulars above enumerated, I endea- 

 voured to inveftigate the matter or fubfiance from which the threads 

 are formed in the body of this infe6t. For this puri)ofe I cut oflftlic 

 heads of feveral Silk-worms whicli had begun to fpin their web or 

 cone, and then I faw, befides the other internal parts, two oblong 



