s allied to our Callosamia Promethea. It
originated from China, where it is cultivated, and was introduced into
Italy in 1858, and thence spread into France, where it was introduced by
M. Guerin-Meneville. Its silk is said to be much stronger than the fibre
of cotton, and is a mean between fine wool and ordinary silk. The worm
is very hardy, and can be reared in the open air both in this country
and in Europe. The main drawback to its culture is the difficulty in
unreeling the tough cocoon, and the shortness of the thread, the cocoon
being open at one end.

The Yama-mai moth (Antheraea Yama-mai) was introduced into France from
Japan in 1861. It is closely allied to the Polyphemus moth, and its
caterpillar also feeds on the oak. Its silk is said to be quite
brilliant, but a little coarser and not so strong as that of the Bombyx
mori. The Perny silk worm is extensively cultivated by the Chinese in
Manchouria, where it feeds on the oak. Its silk is coarser than that of
the common silk worm, but is yet fine, strong and glossy. Bengal has
furnished the Tussah moth, which lives in India on the oak and a variety
of other trees. It is largely raised in French and English India,
according to Nogues, and is used in the manufacture of stuffs called
corahs.

[Illustration: 55. Chrysalis of American Silk Worm.]

[Illustration: 56. Cocoon of American Silk Worm.]

The last kind of importance is the Arrhindy silk worm, from India. It
has been naturalized in France and Algeria by M. Guerin-Meneville, who
has done so much in the application of entomology to practical life. It
is closely allied to the Cynthia or Ailanthus worm, with the same kind
of silk and a similar cocoon, and feeds on the castor oil plant.

The diseases of silk worms naturally receive much attention. Like those
afflicting mankind, they arise from bad air, resulting from too close
confinement, bad food, and other adverse causes. The most fatal and
wide-spread disease, and one which since 1854 has threatened the
extermination of silk worms in Europe, is the _pebrine_. It is due to
the presence of minute vegetable corpuscles, which attack both the worms
and the eggs. It was this disease which swept off thousands of Mr.
Trouvelot's Polyphemus worms, and put a sudden termination to his
important experiments, the germs having been implanted in eggs of the
Yama-mai moth imported from Japan by M. Guerin-Meneville, and which were
probably infected as they passed through P