from an Agricultural and Veterinary Point of View. 51 
Normale, Paris, under whom he became a very competent 
experimentalist. During his studies in chemistry, molecular 
physics appear to have proved very attractive to him, and at last 
to have deeply engaged his attention, the molecular condition of 
crystals forming the chief object of his investigations. The results 
arrived at in his inquiry, when only twenty-five years of age, 
into the symmetrical and unsymmetrical (or dissymmetrical) 
forms of salts apparently identical in chemical composition, were 
remarkable, and elicited the admiration of the chief authorities 
on this subject, and especially of the German chemist, Mit- 
scherlich, who had failed to discover what Pasteur had succeeded 
in demonstrating, though he had devoted many years to it. 
The conclusion Pasteur came to was, that the unsymmetrical 
molecules of matter are produced by, or built up under, the 
influence of vital agencies, the symmetrical being characteristic 
of inorganic bodies, the two conditions being typical of the 
physical barrier that exists between organic and inorganic nature. 
This conclusion has, however, since been questioned, and 
Tyndall, twenty years ago, in his ' Fragments of Science,' was 
inclined to maintain that " it is the compounding, in the organic 
world, of forces belonging equally to the inorganic, that consti- 
tutes the mystery and the miracle of vitality." 
It is very probable that had Pasteur continued to pursue his 
researches in chemistry and molecular physics, he would have 
attained special eminence, and these sciences would have greatly 
benefited. At the early age of thirty-two he was appointed 
Professor of Chemistry at Strasburg, and soon after (in 1854) 
was transferred to Lille, as Dean of the Faculty of Sciences in 
that town, where, for a time, he continued to labour, to verify, 
and to make deductions from theoretic views, until step by step 
he had discovered the startling connection that existed between 
his previous researches in chemistry and crystallographic 
physics, and the new and entirely unexpected results obtained 
in physiological chemistry — which connection finally led him, 
as if it were the thread of Ariadne, to his magnificent disco- 
veries in pathology. 
This series of successes was referred to by the celebrated 
Chevreul at the Academy of Sciences some time ago, when he 
said : " It is by first examining in their chronological origin 
the investigations of M. Pasteur, and then considering them as 
a whole, that we are enabled to appreciate the rigour of judg- 
ment of that learned man in forming his conclusions, and the 
perspicacity of a mind which, strong in the truths which it has 
already discovered, is carried forward to the establishment of 
new ones." 
What might have been considered an accident, led Pasteur 
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