190 
THE ART OF REARING 
should be weaving in the large laboratory when 
the early ones have finished their cocoons. 
4th. When the silk-worm has cast out the down 
which precedes the silk, and it has just begun to 
wind itself in silk, as the air does not then directly 
strike upon them, the care of the interior circula- 
tion need not be so strictly attended to ; and the 
air may be freely admitted now and then, and 
even when it is agitated. 
5th. When the cocoon has acquired a certain 
consistency, the laboratory may be left quite 
open, without fearing the variations of the atmo- 
sphere. The tissue of the cocoon is so close, that 
the agitation of the air, far from being detri- 
mental to the silk-worms, agrees with them, even 
if it should be colder than the temperature fixed 
for the laboratory. 
What I have been stating shews the great 
advantage of having all the worms equal in the 
laboratory, and that they rise at one time as 
nearly as possible. For were there a great dis- 
proportion of time among them, the general 
rearing would not proceed well, and the loss 
would be very great. 
In countries where, by the effects of the cli- 
mate, the temperature is hotter than that which I 
have stated for the period of rising, the air is dry 
without being much agitated as it is in more tern- 
