BUT 
BUT 
tra61:ing thofe claws, and ftriking the feet violently 
againft each other. If, however, the infefts be 
taken from their webs at this time, they appear in 
a ftate of great languor ; and, being incapable of 
advancing or retreating, remain wherever they are 
placed. In this condition they continue one or 
two days, preparing to change into aurelias, fome- 
what after the manner they adopted in changing 
their fivins. They then appear v/ith their bodies 
bent like bows, which they now and then feem 
to ftraighten; their legs appear entirely ufelefs ; and, 
if they attempt to change their places, thefe altera- 
tions are effefted by evident contortions of their bo- 
dies. In proportion as their mutations into aure- 
lias draw near, their bodies become more and more 
incurvated ; while their extenfions and convulfive 
contractions become more frequent. The extremi- 
ties of their bodies arefirfhdifengaged from their ca- 
terpillar fkins ; thofe parts of their fkins remaining 
empty, while their bodies are drawn up in a con- 
trafted form towards their heads. In the fame 
manner they difengage themfelves from the two 
fucceeding rings ; fo that the animals are then en- 
tirely lodged in the fore parts of their caterpillar 
coverings ; the half which is abandoned remain- 
ing flaccid and empty, while the fore parts are 
fwelled and difcended. The animals having thus 
quitted the hinder parts of their ficins, in order to 
drive themfelves up into their fore parts, ftill con- 
tinue to heave and work as before ; till their flculls 
are foon feen to burft into three pieces, and longi- 
tudinal apertures are made in the three firft rings 
of their bodies, jvith reiterated efforts. Thus at 
laft they totally emancipate themfelves from their 
caterpillar fl-cins, and for ever bid adieu to their 
reptile form. 
Being ftripped of it's laft exuvis, the caterpillar 
becom-es an aurelia; in which all the parts of the 
future Butterfly are diftinguifhable, but in fo foft 
and tender a ftate, that the fmalleft touch is capa- 
ble of difcompoflng them. The animal is now 
become helplefs and motionlefs; but only waits 
for the afliftance of the air, to dry up the moifture 
on it's furface, and to fupply it with a cruft capa- 
ble of refifting external injuries. Immediately af- 
ter being ftripped of it's caterpillar fkin, it af- 
fiimes a green colour, efpecially in thofe parts 
which are diftended by an extraordinary afflux of 
animal moifture: but, in ten or twelve hours after 
being thus expofed, it's parts harden j the air forms 
it's external covering into a firm cruft; and, in 
about twenty-four hours, the aurelia may be hand- 
led without endangering the little animal left in 
this defencelefs fituation. 
Such is the hiftory of that fmall pod, or cone, 
which is lb commonly found near every pathway, 
adhering to nettles, and other plants, and frequently 
fhining like poliftied gold. From the beautiful 
and refplendent colour with which it is thus fome- 
times adorned, it has obtained the name of the 
chryfalis, which implies a creature made of gold. 
The above are the eflrorts made ufe of by thefe lit- 
tle animals in preparing for a ftate of perfeftion. 
But their care in providing themfelves fecure re- 
treats during this feafon of extreme imbecillity is ftill 
greater; and it appears as if they were then ere6l- 
ing monuments in which to reft perfeftly fecure till 
Nature called them into a new and more imiproved 
exiftence: for which purpofe, fome of them fpin 
cones, or webs, in which they lie fecure till they 
have arrived at maturity; others, who cannot fpin 
iiich copious coverings, fufpend themfelves by their 
tails in retreats where they are not liable to annoy- 
ance; fome mix fand with their gummy and moift 
webs, and then form themfelves a fecure incrufta- 
tion ; while others, before their change, bury them- 
felves in the ground, and thus avoid the numerous 
dangers attendant on a more expofed fituation. 
From their condufl, it might be fuppofed that 
they were confcious of the precife time of their 
continuance in an aurelia ftate ; fince their little fe- 
pulchres, with refpecl to their fclidity, are propor- 
tioned to fuch a duration. Thofe which are to con- 
tinue in that ftage of exiftence but a few days, make 
choice of fome tender leaf, v/hich they render ftill 
more pliant by difl^ufing a kind of glue over it: 
the leaf thus gradually curls up; and, withering as 
it unfolds, the infcd wraps itfelf within it, till the 
genial warmth of the fun enables it to ftruggle for 
new life, and burft from it's confinement. Others, 
whofe time of transformation is alfo near at hand, 
faften their tails either to fome branch, or to the 
firft worm-hole they meet in a beam, and await 
their change in that defencelefs fituation. Such 
caterpillars, on the other hand, as are feen to lie 
feveral months in their aurelia ftate, acl v/ith much 
greater circumfpeClion : moft of them mix their 
webs with fand, thereby rendering their coverings 
veryftrong ; while others build in wood, which fup- 
plies, as it were, the place of coffins. Thofe which 
have made the leaves of willows their fivourite food, 
break the tender twigs into fmall pieces, and then 
pound them to a fort of powder ; and, by means of 
their glutinous filk, form a kind of pafte, in which 
they enwrap themfelves. 
Various are the forms which thefe animals af- 
fume in this ftate of imbecillity; and it often hap- 
pens that the moft deformed Butterflies iflTue from 
the moft beautiful aurelias. In general, however, 
the aurelia afiumes the rude outlines of the parrs of 
the animal contained within it ; but, as to the vari- 
ous colours which it is feen to aftume, they are 
chiefly the efi^e6l"s of accident; for the fame Ipecies 
of infe£t does not at all times afiume the fame hue 
when it becomes an aurelia. In fome, the beauti- 
ful gold colour is found at one time; while, at ano- 
ther, it is totally wanting. This brilliant hue, 
which is not inferior to the moft fuperb gilding, is 
formed in the fame manner in which we fee leather 
obtain a gold colour, though none of that metal 
ever entered into the tinfture. It is formed only 
by a beautiful brown varnifli laid on a white 
ground ; and the v/hite, thus gleaming through the 
tranfparency of the brown, "imparts a charming 
golden yellow. Thefe two colours are found, 
one over the other, in the aurelia of the little ani- 
mal we are now defcribing ; and the whole appears 
as if gilded, without any real compofition. 
Thus formed, the aurelia is in time expanded 
into a Butterfly, and fomewhat refembles an ani- 
mal in the egg, waiting for external warmth to 
hatch it into life. As the quantity of humidity in- 
clofed within the covering of the aurelia continues 
to keep it's body in the moft tender ftate, it is 
requifite that this humidity ftiould be dried up be- 
fore the little Butterfly can burft from it's prifon. 
Many experiments have been pra£liled, in order to 
prove that nature may in this relpecfl: be aflifted by 
art ; and that the life of the infed: may be retarded 
or quickened without being expofed to any real in- 
jury: for this purpofe, it is only necefiary to con- 
tinue the infe6t in it's aurelia ftate, by preventing 
the evaporation of it's humidity, which wiU confe- 
quently add fome days^ or even weeks? to it's life ; 
2 K on 
