Of the silk WORM. 



1 HE Royal Society having rccominended to my examination, tlie 

 fruitful and barren eggs of the Silk- worm, I procured a number of 

 tliofe eggs, which had been lately laid by the Moth or Butterfly 

 produced from that infc^l ; this was about the beginning of the 

 month of September. Thefe eggs, when firft laid, were of a yel- 

 lowilh colour, which in about two days time affumed a reddilli call, 

 and at fix days end they appeared to the naked eye of a liver colour, 

 feveral of tliem I opened, by taking off the upper part of the 

 fliell with as light a touch as poflible, and in every one of them I 

 obferved an exceeding fmall and delicate membrane, which to the 

 naked eye appeared blackifli, but on examining it by the microfcope, 

 I found the real colour to be violet, but where the violet particles 

 compofing it lay clofe together, they afiumed a blackifli appearance. 

 Tliis membrane lay next to the fhell of the egg, and I imagined, 

 that within it the future Silk-worin would be formed ; and in tiie 

 part where this membrane was joined to the fliell, I faw a minute 

 Ipeck or fpot, which I concluded to be the vital principle, and the 

 rather, as this fpeck was wanting in thofe eggs whicli I found to be 

 afterwards barren ; and it is further to be noted, that in the barren 

 eggs no fuch membrane as I have mentioned was formed, nor did 

 they change their original yellow colour. This membrane in a fliort 

 time extended over the whole infide of the egg, and being feen 



through the fhell, which is tranfparent, caufed it to appear of a 

 Muifli colour. 



Some of thefe eggs, which were fix weeks old, I put into a flat 



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