162 
THE ART OF REARING 
another substituted. Great care should be taken 
not to hurt or bruise the worms in removing 
them. Six persons, at least, should be employed 
to perform this cleaning of the litter expedi- 
tiously, and in their number I do not include 
those who carry the litter out of the laboratory. 
This litter has no unpleasant effluvia, and is as 
green as the leaf itself ; and the paper upon 
which it lay is only a little damp. 
This change of the litter will employ eight 
hours ; and, therefore, in this period the silk- 
worms that have been cleaned should be fed, and 
those that are to be cleaned last, may be fed 
before they are cleaned, that none of them may 
fast too long. 
It must not be forgotten, that during this 
operation, as the case may require it, there should 
be light blazing fires burnt, and the fumigating 
bottle should be passed twice round the labora- 
tory ; the windows and ventilators should be 
opened, according to the state of the exterior 
atmosphere, but in all cases the ventilators in the 
ceiling and floor, and all the doors, must be open. 
If the exterior air be very damp, which would 
indicate that of the laboratory being still more so, 
the small blazing fires in the angle fire-p laces 
may be frequently repeated. And if this should 
raise the temperature too much, it may easily be 
lowered, by opening the ventilators and windows. 
