344 'Exfetiments and Ohfervations 



and conceals them in the crevices of trees^ prepoireflcd nie- 

 in their favour. 



On the 36th of March 1800, I put on two pieces of white 

 paper feveral of thefe eggs, which I covered with fniall bells 

 of very thin glafs, taking care to leave a fmall aperture at 

 their fummits to maintain a circulation of air, I varnilhed 

 one of them black, and expofed them to the fouth. 



At the end of fome days the eggs which were under the 

 tranfparent bell became coloured and dry, and all thofe. 

 under the black bell were hatched on ihe jith of April. I 

 repeated on thefe eggs the experiments of the tul)es im- 

 merft'd in water, and the refult was equally decifive, fince 

 I faw hatched not only all the eifgs contained in a bent glafs 

 tube covered. with a very thin plate of lead, but flill they 

 preceded others which, though placed alfo in a dark place, 

 were not immerfed in water. 



In regard to thofe contained in the tranfparent tufee, they 

 all peri(hed. At firft they exhibited no fenfible fign of any 

 change : afterwards they began to become a little coloured ; 

 they then daily affumed a redder colour, but they did not 

 perifli altogether till the lad days, during which thofe 

 in the covered tube were hatched. 



From thefe different experiments we may therefore con-r 

 elude, that light has a df cided action on thofe germs which 

 are dxpofed to it; that this aclion is prtjudicial to them ; 

 aijd, in the lad place, that it manifefts its aC/tion by retarding 

 their expanfion if the light be weak, or a rcfle6led light, or 

 by the total exlin6lion'of their life if it be very intenfe, as 

 that which comes di really from the fmi. 



To thefe fa6};s if I add, that the expanfion of viviparous ani- 

 nials begins and is completed in darknefs ; that oviparous 

 animals produce eggs with an opake Ihell, as thofe of birds, 

 8cc. that^if the eggs hi^ve a delicate fliell the mother gene- 

 rally depoiits them in dark and copcealed places, where (lie 

 Covers thehi with hair, earth, &c. we fliall be inclined to 

 thii)k that the aftion of light is generally prejudicial to thq 

 fexpanfiqn of the germs. But in what manner does it hurt 

 thenu— rThis is what I fhall endeavour to explain. 



|t may be conceived th?it the a^idn 'of light can hurt 



