| sented in Fig. 203, and remains 
|in it in a state of immobility 
which has been called sleep Fie, 
LEPIDOPTERA. 225 
In consequence of this having been remarked, some manutac- 
turers have attempted to obtain their silk directly from the 
mulberry leaf; but they only got a bad floss or refuse silk. This 
is because the silk is not formed in the mulberry leaf. The 
organs of insects are laboratories, in which manipulations un- 
known to man are carried on, manipulations which he has not 
been able to reproduce. 
After this rapid glance at the fundamental parts of the organism 
of the silkworm, we will occupy ourselves with the natural history, 
properly so called, of this insect, and with its rearing, carried on 
with a view to the production of silk. 
As belonging to the first part of this programme, we have to 
speak of the moult, of the ages of the silkworm, of its maturity; 
of its mounting or ascending season, of the formation of the cocoon, 
of the chrysalis, of the moth, and the egos, 
The name moult has been given to a sort of crisis during which 
uhe renewing of the skin of larve takes place. When it ap- 
proaches, the silkworm changes its colour. Its robe, which was 
white or grey, and opaque, becomes yellow 
and more transparent. The head swells con- 
siderably, especially above, and the skin becomes 
wrinkled (Fig. 202). The worm then fasts, 
and prepares to cast its skin. It places here igo open per 
and there some silk threads on the sur-  wormduring moulting. 
rounding objects. It then slips under these threads, so that 
during its movements the old skin it abandons is, so to speak, 
picked up. It then assumes a 
peculiar position, that repre- 




203.—Position of Silkworm while moulting. 
(sommeil). 
During this sleep the new skin is formed under the old. <A liquid 
oozes forth between the two membranes which separates them, and 
| allows the silkworm to leave its old skin. To effect this, the worm 
begins by raising its head, and by making contortions. The old skin 
splits round the muzzle or snout, on the head and back ; then by dif- 
ferent movements the animal emerges from its skin, which remains 
Q 

