properties, the acid derived from asparagin, that Des-
saignes, who had no preconceived idea to put him on
his guard, was very excusable for having confused the
two.

This synthetic aspartic acid is especially interesting in
that it can be transformed into malic acid by the methods
of Piria, and we may well believe that Pasteur was
curious to know what malic acid one would obtain with it.
Experiment shows that we obtain a malic acid identical
with the natural acid, save that it is inactive on polarized
light, as are also its salts. This is not all; the field
grows more fertile as we cultivate it. The active malic
acid of the sorb-tree or of the grape corresponds to one
of the active tartaric acids. To what was this now malic
acid comparable? To the paratartaric acid inactive by
compensation? Pasteur had, against this interpretation,
an objection which is no longer valid. " Dessaignes,
the father of this malic acid, would "he thought, "in
this case have created two molecules endowed with
rotary power at the expense of one inactive molecule,
but it is impossible to create a single active molecule, to
say nothing of two." We know today, not only that
the thing is possible, but that it has been realized.
It is very probable, if not absolutely demonstrated,
that the aspartic acid manufactured by Dessaignes was
a combination of the right- and left-handed acids. It
is certain that the malic acid which Pasteur had had in
his hands was also a paratartaric acid. This error at
the outset vitiated the memoir which Pasteur had
devoted to comparing the aspartates and malates with
each other and with the tartrates. The majority of
the deductions which he had drawn from these compari-
sons are inexact, and must be abandoned. But there
are some which survive and which we should note.
Even in the early years of his life as savant, Pasteur

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