118 
THE ART OP REARING 
age. It is only necessary to note on each hurdle 
its dimensions and the number of square feet ; by 
which means in a moment may be seen which are 
the hurdles which must be used for this age, as 
well as for the preceding ages. 
1 must here repeat how advantageous to the 
art of rearing silk-worms is the practice of dis- 
tributing them in regular strips and squares, 
which should be extended, and widened, and gra- 
dually filled with these insects, as they accom- 
plish their various ages, and particularly as the 
hurdles are not cleaned in the fourth age, the 
litter, that spreads by degrees, not heating or 
contracting any effluvia, and not rising much. 
2d. Because the leaf distributed upon evenly 
portioned spaces is entirely eaten before it is wi- 
thered and spoilt. 
3d. Because, by this practice, the worms can 
feed with facility, move with ease, and breathe 
more freely, all decisive advantages for these 
insects. (Chap. XIII.) 
He must forego these advantages when the 
worms lie too thick ; in that condition they cover 
the surface so closely, that the leaves on which 
they lie are wasted, as they cannot possibly eat 
them ; while, on the contrary, when they have 
plenty of room, they seek, in moving, every atom 
of the leaf, and eat it up. Besides, when straight- 
ened, the action of their breathing-tubes is hin- 
