SILK-WORMS. 
231 
admit of no difference among these qualities, and 
that I firmly believe that all the impregnated 
eggs obtained by the methods previously de- 
scribed, are always fit to produce good silk- 
worms, provided they have been well preserved. 
The true difference in the qualities consists in 
the great number of eggs not impregnated, that 
are found among the sorts that are called infe- 
rior *. 
* When the third laying' takes place, and it is found 
to contain many yellow unimpregnated eggs, or reddish 
ones imperfectly impregnated, if it is desirable to know pre- 
cisely the quantity of impregnated eggs from which worms 
are to be obtained, that must be done which is pointed out 
in the note of page 67. 
The whole of the eggs placed in the stove-room are 
weighed ; the few silk-worms which are hatched the first, 
and afterwards the third day, are thrown away ; then the 
eggs remaining are weighed, and adding to this weight the 
twelfth part, to allow for the evaporation which they have 
undergone, you will have the weight of those which shall 
have produced the worms. 
If the eggs were in great quantity, and you can take away 
separately the worms that they may have produced, you may 
keep also those born on the fourth day, if they were in suffi- 
cient quantity. When the weight of the eggs put in the 
stove-room is exactly known, when you can easily separate 
the empty shells of those which have produced worms, to 
weigh those which remain, and when one knows what is to 
be added to the weight of the eggs that are not yet burst, 
and how the weight of the worms hatched the first day, and 
rejected, is to be calculated ; it seems to me that nothing 
more is required to enable us to proceed with the greatest 
precision. 
