166 
THE ART OF REARING 
During the last days of the rearing of the 
worms, they should be fed with the best sort of 
leaves, always culled from the oldest trees. 
The silk-worms now advance towards maturity, 
which may be perceived by their yellow colour, 
which increases from ring to ring. 
The backs of the silk-worms begin to shine, and 
the rings lose the dark-green colour that marked 
them. 
The advance to maturity is also denoted, in 
some of them, by the diminution of their bulk in 
the course of this day, and by their seeking 
to fix' themselves to the edge of the hurdles, to 
void the substances with which they are loaded. 
This day, and more or less speedily, according 
as the signs of maturity increase, and that the lit- 
ter gets moist, the wickers should be cleaned in 
the manner we before described, being very care- 
ful to take the worms gently with the leaves upon 
which they lie, that they may not be bruised. 
Light fires, and the fumigating bottle to purify 
the air, the ventilators, and the use of the ther- 
mometer and hygrometer, are in this change of 
litter more essential than on any former change. 
The smell of my laboratory is always fresh and 
pleasant ; while the hurdles are cleaning, the lit- 
ter is always sweet and green, and a little damp. 
