“NATURAL HISTORY. "3 
&& with much greater circumfpedion. Moft of them mix their web 
With fand, and thus make themlelves a ftrong covering: others build 
‘2 wood; which ferves them in the nature of a coffin. Such as ‘have 
Made the leaves of willows their favourite food, break the tender twigs 
f them firft into fmall pieces, then pound them as it were to powder ; 
8nd, by means of their glutinous filk, make a kind of paite, in which 
they wrap themfelves up. Many are the forms) which thefe animals 
Ulume in this helplefs ftate; and it often happens, that the moft de- 
Ormed butterflies iffue from the moft beautiful aurelias. 
In general, however, the aurelia takes the rude outline of the parts 
Sf the animal which is contained within it; but as to the various 
Solours which it is feen to affume, they are rather the effect of accident ; 
for the fame {pecies of infeét does not at all times affume the fame hue, 
When it becomes an aurelia. In fome, the beautiful goldicolour is az 
“One time found; in others; it is| wanting... This brilliant hue, which 
oes not fall fhort of the be@ gilding, is formed in the fame manner 
M which we fee leather obtain a gold colour, though noné of that me-~ 
‘Tal ever enters into the tin@ure. It is only formed by a. beautiful 
Drown varnifh, laid ypon a white ground; and the white thus gleam- 
“Ng through the tranfparency of the brown, gives a charming golden 
Yellow. héfe two colours are found, one over the other, in the au. 
Telia of the little animal we are defcribing ; and the whole appears gild- 
“€d, without any real gilding. ra d iatce od 
, ‘The aurelia thus formed, and left to time to expand into a butterfly, 
‘ fome meafure refembles an animal in an egg, that is to wait for ex-, 
‘temal warmth to hatch it*into life and vigour. As the quantity of 
‘Moifture that is enclofed within rhe covering of the aurelia, continues 
to keep its body in the moft tender ftate, fo it is requilite that this hu- 
“Midity fhould be dried away, beforé the little butterfly.can burft its 
Prifon. Many:have been the experiments to prove that Nature may in 
‘this refpeét be afliftted by art; and that the life of the infe& may be re- 
larded or quickened, without doing it the fmallef injury. For this 
‘Purpofe, it is only requifite to continue the infe@ in its aurelia flate, by 
Preventing the evaporation of its humidity; which will confequently 
d fome days, nay weeks, to its life: on the other hand, by eva- 
“rating its moifture, in a warm. fituation, the animal affumes its 
Winged tate before its ufual time, and goes through the offices afligned 
US exiftence. “To provethis,, Mr Reaumur enclofed: the aurelia in a 
afs tube ; and found the evaporated water, which exhaled from the 
dy of the infed, collected in drops at thé bottom of the tube: he 
®Vvered the aurelia with varnifh; and this making the evaporation 
Sre difficult and flow, the: butterfly was two months longer than its 
_ tural term, in coming out of its cafe v he found,.on the other hand,’ 
af by laying the animal in a warm room, he haflened the difclofure 
"ih the butterfly ; and by keeping it in an ice-houfe in the fame manner, 
€ delayed it. Warmth aéted, in this cafe, in a double capacity ; in- 
'$9rating the animal, and evaporating the moifture, pega 
"y a aurelia, though it bears\a’ different external appearance, never- 
ic €{$ contains within it all the parts of the butterfly in perfect forma- 
3 and lying each in a very orderly manner, though in the finalle/: 
< OMpats, Thefe, however, are fo falt and tender, that it is impollible’ 
.. “iit without difcompofing them: When either by warmth, or in- 
HS creafing 
