in the laboratory, where his assistants saw only the ex-
terior and the skeleton of his experiments, without any
of the life which animated them. Here, on the contrary,
he was under obligation as soon as he had found out
something to speak and to excite the public judgment
and that of industrial practice on all his laboratory
discoveries.

A hard necessity, that of laboring thus under the public
eye, with an official connection, in the presence of a men-
acing danger which one has been commissioned to exor-
cise! to be sent to combat a conflagration, and not to
know where the fire is, and not to have any pumps! One
must be a Pasteur to accept such a responsibility and
carry it off successfully. In any event, we owe to this
condition of things a multiplicity of documents: reports
to the Academy of Sciences, to the Minister of Agri-
culture, letters to M. Dumas, communications to the
journals of silk culture, and we can make use of all these
signed writings of Pasteur to reconstruct the history of
his thought. He has himself authorized us to consult
them by inserting them at the end of the second volume
of his Études sur la maladie des vers ὰ soie. "I might
have dispensed with reproducing in toto these pub-
lications," he says, "since the first volume contains the
definite expression of my actual ideas; but I have thought
that they might be of some historical interest and serve
as an example in a difficult and long-winded subject
of the progressive march of ideas in proportion as the
observer multiplies his experiments.

"'Let us gather together some facts in order to have
some ideas' said Buffon. It is not without utility to
show to the man of the world or to the practical man
at what cost science conquers principles the simplest and
most modest in appearance." ¹