se devotion to
experiment. Thanks to M. Delafosse, one of the lecturers of the
Ecole Normale, his attention was turned to crystallography, and a
note from the German chemist, Mitscherlich, communicated to the
Academy of Sciences, set him on fire with curiosity. Mitscherlich
declared: "The paratartrate and the tartrate of soda and ammonia
have the same chemical composition, the same crystalline form, the
same angles, the same specific weight, the same double refraction,
and the same inclination of the optic axes. Dissolved in water,
their refraction is the same. But while the dissolved tartrate
causes the plane of polarized light to rotate, the paratartrate
exacts no such action."

Pasteur at once instituted experiments resulting in the discovery of
minute facets in the tartrate which gave it the power noted. He
found in the paratartrate these facets existed, but that there was
an equal admixture of right-and left-handed crystals, and the one
neutralized the effect of the other. He also discovered the
left-handed tartrate. These discoveries at the opening of Pasteur's
career brought him at once to the front among the scientific men. He
followed them with a profound investigation into the symmetry and
dissymmetry of atoms, and reached the conclusion that in these lay
the basic difference between inorganic and organic matter, between
the absence of life and life.

Nominated at the age of thirty-two as Dean of the Faculte des
Sciences, at Lille, Pasteur determined to devote a portion of his
lectures to fermentation. At that time ferments were believed to be,
to quote Liebig, "Nitrogenous substances--albumin, fibrin, casein;
or the liquids which embrace them--milk, blood, urine--in a state of
alteration which they undergo in contact with air." Pasteur examined
the lactic ferment and found little rods, 1/25000 inch in length,
which nipped themselves in the centre, divided into two, grew to
full length and divided again, and these living things he declared
to be the active principles of the ferment. He made a mixture of
yeast, chalk, sugar, and water, added some of the rods, and got
fermentation. He then made a mixture of sugar, water, phosphate of
potash, and magnesia, and introducing fresh cells, fermentation
followed. Liebig's theory of the nitrogenous character of the
ferment disappeared when fermentation was caused in a mixture having
no nitrogenous elements.

Pasteur had discovered that fermentation was a phenomenon