CH. v.] HISTORY OF SILK, ETC. 99 



silkworm will be very apparent. When eggs have 

 been kept in a certain degree of warmth, it requires 

 less stove-heat to develop the silkworm ; this is so 

 true, and so worthy of notice, that we find, if in 

 winter the eggs have been kept in an atmosphere 

 of 55° or 59°, or heaped together, they come forth, 

 without the aid of the stove, spontaneously when 

 the room is but slightly warmed, and before the 

 mulberry-tree has given any signs of vegetation ; 

 in this case these worms must be thrown away. 



The eggs of different proprietors, placed in the 

 same room, under the same circumstances, are 

 found not to be hatched at the same time. Those 

 which during the winter have been kept at a higher 

 and more even temperature, come forth four or five 

 days earlier than others. 



The following extract from Dandolo exhibits the 

 power and the utility of temperature in the art of 

 rearing the silkworm. 



" A prudent proprietor has done all in his power 

 when, on observing the season favourable, and the 

 bud of the mulberry-shoots in a proper degree of 

 forwardness, he has put the eggs into the stove- 

 room. Should the weather suddenly change, as it 

 did in 1814, it is then of great use to have the power 

 of backing the hatching of the eggs without injur- 

 ing the worm, as I have before stated, and to prolong 

 their two first stages by a few days. To obtain this, 

 the only method is, after the worms have been re- 

 moved into the laboratory about five hours, to lower 

 the temperature- to 73° from 75°, four hours after 

 further to lower it to 71°, and the following day to 

 68°, if necessary. 



" This cooling of the air diminishes the hunger of 

 the young silkworm by degrees, and without danger; 

 and by these means the modifications are prevented, 

 which, at 75°, would have brought on the casting 

 or moulting much more speedily. 



"At 75° the first moulting is effected the fifth 



