S I L 
the feafon ; fo that thofe frofts whofe influence is 
ftrono; enough to kill the tree, can feldom hurt 
the Siik-Wonn. 
Thefe infefts never proceed from the eggs till 
nature has provided them a proper fupply ; and 
till the budding leaves are furnifhed in ample 
abundance for their llipport. When the leaves 
are expanded, the Vv^orms feem to feel the gene- 
ral invitation; and burfting from their little eggs, 
crawl on the leaves, where thev feed with a inoft 
voracipus appetite. Thus they become larger by 
deri'rees ; and, after fomiC months feeding, they de- 
poft, on every leaf, fmall bundles or cones of filk, 
which appear like fo many golden apples painted 
on a fine green ground. 
Sucli is the method of breeding them in the 
Eaft; and it is unqueftionably moft agreeable to 
ttie nature of the Worms, as well as leafttrouble- 
fome to their proprietors. But it is far otherwife 
in our colder European climates: tlie frequent 
changes of the wearher, the heavy dews of our 
evenings, and a variety of other confequences re- 
fuking from fituation, render the keeping them, 
all night expofed, fubieft to fo many inconve- 
niencies, as to admit of no remedy. It is true 
that, by the affiftance of nets, they may be pre- 
fcrved from the depredations of birds; but the fe- 
vere cold weather which frequently fucceeds the 
firll heats of fummer, as well as the rain and high 
winds would utterly extirpate them: and tliere- 
fore, to breed them in Europe, they muft be care- 
fully fheltered and protefled from external injury. 
In order to effe<5l this, a room fhoukl be fclefted 
with a fouth afpeft; and the windows glazed with 
the utmoft exaClnefs, that every breath of air may 
be kept out: the walls alfo fhould be 'well built; 
and the planks of the floor laid fo extremely clofe, 
that not an infed" can make it's way into the place 
deilined for the reception of the Silk-Worms. 
In the m.iddle of the room four pofts fhould be 
erefted, fo arranged as to form a fquare of pretty 
confuierable extent: bctv/een thefe different ftorics 
ihould be made with oHer hiirdles; and under 
each iiurdle a Hoor, with an upright border round ; 
and thele hurdles and floors fhould hang on pul- 
lics, fo as to be placed or taken down at plea- 
fure. 
When the Worms are hatched, fome tender 
mulberry-leaves fhould be laid in tlie cloth or pa- 
per box wherein the eggs are depofited, and which 
are fufnciently capacious to contain a confider- 
ahle number. When they have acquired fome 
frrength, they m.uft bediftributed on beds of mul- 
berry-leaves, in the different flories of the fquare 
in the centre of the room, round which there , 
fiiould be fuScient fpace for a perfon to pafs with 
freedom: on thefe leaves they will fix themfelves; 
and afterwards on the fticks of the hurdles, when 
the leaves are devoured. They have then a 
thread, by which they can occafionally fufpend 
themfelves, to prevent any fliock by a fall: this, 
however, is by no means to be confidered as any 
portion of the filk which they afterwards fpin in 
luch abundance. Care muft be taken to fupply 
them v;ith freiii leaves every morning, which muft 
be ftrevved very gently and equally over them; 
when the Silk- Worms will forfake the fragments 
of the old leaves, which mufl be carefully re- 
moved, and the whole kept in a flate of the mofi: 
pcrft cl neatneis, nothing being more injurious to 
thefs infects than moifture and nailinefs. For 
this realon, their leaves muft be collected during 
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dry weathef, and kept in a like fituation, fliould 16 
be neceffary to lay in a ftore. 
As thefe animals enjoy but a very limited cx- 
iflence, they hufband every moment; and are al- 
mofb continually engaged in fpinning, except at 
thofe intervals when they change their fkins* 
Should there be any difficulty in obtaining mul- 
berry-leaves, they may be fed with thofe of let- 
tuce or holy-oak: but they do not thrive fo well 
on this ftrange diet; neither will their filk be fo 
copious orfo beautiful. 
A judicious choice and attentive management 
of their diet is abfolutely neceflfary. But this is 
not all: there is another precaution of equal im- 
portance, which is to give them air, by opening 
the vv-indows of their apartment at fuch fealbns as 
the rays of the fun are mofl powerful. Thefe 
matters carefully obferved, together with a due 
attention to cleanlinef's, will wonderfully contri- 
bute to their health and increafe. 
At the time the Worm burfls it's fhell, it is 
extremely fmall, and of a black colour; but the 
head is of a more fhining black than the reft of 
the body. Some days after, it begins to turn 
Vvhitifh, or of an afh-coloured grey; and the (kin 
beginning to grow too rigid, or the animal be- 
ing ftinted in it, throws it off, and appears 
cloathed anew. It then becomes larger, and 
much v/hirer, though it flill has a greenifh cafi ; 
and, after fome days, which are determined by the 
heat of the climate or the quantity and quality of 
it's food, it leaves off eating, and feems to enjoy 
a ftate of perfefl' repofe for two days together. 
After this it begins to ftir, and put itfelf into vio- 
lent motions, till the fl<in falls off a fecond time^ 
and is throv/n afide by the animal's feet. All 
thefe transformations are undergone in the fpace 
of three weeks or a month; which being ended, 
the infeft begins to feed once more in it's cater- 
pillar ftate, but confiderably different from what 
It W a s before it changed. In a few days time, it 
feems to fleep again; and, when it av/akes, again 
changes it's covering, and continues feeding as 
before. When it has thus obtained a lufficiency 
of food, and it's parts are difpofed for afTuming 
the aurelia form, the animal, for the laft time, for- 
fakes all food and fociety, and provides a retreat, 
to prote6t itfelf from external injuries while ap- 
parently deprived of life and motion. Tiiis re- 
treat is no other than it's cone or bag of filk, 
which nature has taught it to compofe with fur- 
prifing art; and within which it buries itfelf till 
it alfumes it's win2;ed form. This cone or ball is 
fpun from two little longifh kind of bags, lying 
above the inteftines, and filled with a gummy fluid 
of a bright yellovv' colour : from this fubftance the 
threads are formed; and the little animal is fur- 
nifhed with a furprifing apparatus for fpinning it 
to th,e requifite degree of finenefs which it's exi- 
gencies require. The inftrument with which this 
operation is performed in fome meafure refern- 
bles a wire-drawer's machine, in j;<.'hich gold or 
filver threads are extended to any degree of mi- 
nutenefs; and through this the animal draws it's 
thread with great afTiduity. As every thread pro- 
ceeds from two gum bags, it is probable that each 
fupplies it's own; which, however, are united as 
they proceed from the animal's body. If the 
thread be microfcopically examined, it will be 
found flatted on one fide, and grooved along it's 
leno-th : from hence v/e mav infer, that it is d6u- 
bled immediately on leaving the body j and that 
the 
