SILK AND SILKWORMS. 95

varies, indeed, according to the climate or temperature in
which its life is passed ; all its vital functions being quick-
ened, and their duration proportionally abridged, by
warmth. With this sole variance, its progressions are alike
inall climates, andthesame mutations accompany its course.

There are several varieties of the silkworm, producing
almost as many coloured silks—bright and pale yellows,
white, and brown—and usually one, but sometimes two
or more crops in the year. The most beautiful of the
species is that found on the banks of the Rio Doce, in
Brazil; the colour of which is a bright emerald green.

TUSSEH SILKWORM.

It feeds on the leaves of the palma christi, or castor-oil |
plant. A second, also found in a wild state in the jungles |
of Bengal, is the tusseh, which yields an earthy-coloured |
silk, and of too poor a quality for an article of commerce. |
But long experience has demonstrated that no silkworm
surpasses that which is commonly educated in Italy.
“The silkworm being subjected to domestic care and
habits,” remarks Dandolo, “ must necessarily, like every
other domesticated animal, have undergone particular
modifications, which have produced new kinds and
varieties, more or less different. It is thus we account
for some insects moulting, or casting their skins, four
times, and others only three times; thus some form large
cocoons nearly thrice the weight of the common cocoon ;”
which last-mentioned resembles a pigeon’s egg both in
its size and shape.

Cocoon.

The number of crops of silk in the year depends upon |

the growth of the natural food of the insect—namely,
the muiberry-tree. In the neighbourhood of Florence,
the inhabitants cause the worm to be hatched at two
separate periods. The first brood is fed on the first leaves
of the spring ; and when these have gone through their
progressions, and have produced silk, other eggs are
hatched, and the insects are nourished by a second crop
of leaves furnished by the same trees. This plan has

been followed in China, from time immemorial, where two |

crops of silk are obtained in the year; and it is reported,

that in some other parts of Asia as many as twelve broods
of worms are reared in the course of as many months.
In the Isle of France three generations of insects have
been obtained between the months of December and May;
the mulberry-tree there, as well as in India, affording
fresh leaves through the whole year.

The time employed by the silkworm in Italy, from
the period of hatching until it deposits its eges and dies,
is about sixty days. A higher temperatme than 75°, which
is commonly allowed to be the best adapted for its
growth, will shorten that period. If the artificial heat
were 10° or 15° greater, and uninterrupted, the worms
might be brought to spin in less than five-and-thirty
days; but such an increase of heat exposes them to danger.
In five days they are supposed to have finished their
cocoon. In twelve days, the moth succeeds to the chrysalis,
and bursts its way through the silken envelope in which
it has surrounded itself. In a few hours it deposits its
eggs—from 300 to 500 in number—and in a few days it
dies; and thus terminates the brief life of this extra-
ordinary and useful little creature.

Its natural food, as before intimated, is the leaf of the
red or white mulberry; the former of which is deemed
better.than the latter. The insect, however, will feed as
voraciously upon the milk thistle, the leaves of lettuce,
spinach, and blackberry, the young leaves of the elm, and
the leaves and flowers of the sweet cowslip and primrose.
But, for some unknown reason, it will never touch any
flower or leaf of a roseate hue. The Italian race of worms
are nourished entirely on the mulberry leaf. Fed on any
other food, they will not only degenerate, but are subject to
diseases from which those are exempt which are properly
| fed. As an article of diet, lettuce ranks next to mulberry.
| A series of interesting experiments, which were made in
| this country at the close of last century, and which are!
recorded in the Transactions of the Society for the En-
| couragement of Arts, &c., revealed the fact that the
| mortality of the insect, when fed exclusively upon lettuce,|
| resulted, not so much from the unwholesomeness, as from|
the coldness, of that herb. A gentleman, it is said,|
“caused a considerable number of worms to be hatched |
| and reared in his hot-house. These were fed entirely on|
| lettuce leaves. They throve, and went through their}
mutations as satisfactorily as if fed with their natural)
aliment; scarcely any among them died, and the number
and quality of the cocoons that were gathered proved the
entire success of the experiment.”

We shall conclude this paper with a few practical!
suggestions for the education of the worm, culled from |
the pages of the late Mrs. Whitby’s very excellent, and)

Some of our younger readers}

now excessively rare tract.
will doubtlessly find opportunities for turning them to pro-
fitable account. That lady obtained the insect from various
sources, or rather, as we should have said, its ova or,
graine, which, she tells us, yielded the following results :—

77 English cocoons gaye of reeled silk 4 OZ.

460 Poitiers a oS 1 OZ.
480 Bordeaux 3 50 1} 02.
213 Italian y ff OZ.

For this silk she readily obtained in the English market
24s. per lb. The manufacturers at Coventry “ expressed
the greatest surprise and admiration at the superior
quality of the material; which they found ‘to handle’
quite as well as first-rate Italian.” Her sole aids in the
management of the magnanerie, or worm-house, during