SIXK-WORMS. 
51 
days sooner, name]}', at the 71st, 73d, or 75th 
degree of tempera ture ; whilst those that have 
been kept in a very cold atmosphere appear some 
days later. 
This stove imparts to each egg the degree of 
heat necessary to change the embryo it contains 
into the worm. When the eggs have been kept in 
a certain degree of warmth, it requires less stove 
heat to develope the silk-worm. This is so true, 
and so worthy of notice, that we find, if in the 
winter the eggs have been kept in an atmo- 
sphere of 55 ° or 59°, or heaped together, they 
come forth without the aid of the stove spon- 
taneously, when the room is but slightly warmed, 
and before the mulberry-tree has given any sign 
of vegetation. In this case these worms must be 
as to the degree of temperature to which the eggs have been 
exposed, and how many degrees may be wanting to complete 
their vivification in the stove-room ? Can it be calculated 
how high the degrees of the thermometer should be raised in 
the stove-room, to receive these macerated eggs, without 
injuring the embryo, or the progress of the silk-worm ? 
This uncertain method must needs be injurious to the regular 
and secure development of the worms. I have myself often 
seen great quantities spoiled by maceration, the worms 
coming forth, and shortly dying. 
It appears to me rational that, when there appears to be 
a certain and regular method, we should not adopt another, 
the result of which is uncertain and irregular, particularly 
when this secure method is not attended by any exorbitancy 
of expense, as I have iust shewn, in the preceding note, and 
in Chap, IV. § 4. 
D 2 
