silk-growers," whether a lot of cocoons will give you sound
eggs? Take a portion of them and heat them so as to
hasten four or five days the hatching of the moths, and
see whether the latter are corpuscular. The micro-
scopical examination of the moths is easier and more
certain than that of the eggs because in them the cor-
puscles are many times more abundant. If the moths
are bad, send the cocoons to the spinning mills. On
the contrary, if you find that only a very limited number
of individuals are diseased, allow them to develop:
the eggs will be good and the brood which you will have
from them the next year will be a successful one. Only,
this brood will be unfit for breeding because of the initial
presence and multiplication in it of the corpuscles.
But do you wish the brood to be sound up to the very end
and give you perfect eggs? Then take absolutely sound
eggs, coming from absolutely pure parents, and hatch
them in conditions of cleanliness and isolation, such
that infection cannot spread there. But if, unfortu-
nately, the disease should appear I still give you the
means of making a selection, and of separating rigorously
the sound eggs from the corpuscular ones."

The problem was, therefore, solved, and the victory
could be considered complete. Let us hasten to say that
no part of it is more widely discussed at the present time.
The examination of eggs with the aid of the microscope
which had been judged impossible has become a custom.
The growers of silkworms have made it encircle the globe
as they once did the disease itself, and pébrine has
ceased to haunt the mind of those engaged in the silk-
worm industry. On one point only were the expecta-
tions of Pasteur unfulfilled. He hoped that it would be
possible to make the disease disappear. This was a
noble ambition and would have been a great example.
Experience has shown that it was impossible. This is

-172-