54 
Pasteur and his Work, 
combustion ? How is the disappearance of the dead body, or of 
the fallen plant, to be accounted for ? What is the explanation 
of the foaming of the must in the vintage-cask ? of dough which, 
left to itself, rises and becomes sour? of milk, which curdles? 
of blood, which putrefies? of the heap of straw, which becomes 
manure? of dead leaves and plants buried in the earth, which 
are transformed into soil ? 
The attempts to solve the problem were numerous, but the 
hypotheses of the chemists were generally accepted, and Pasteur, 
being a chemist, might be supposed to favour one or other of 
these. Not so, however. The inductive method of study and 
research was his guiding star, and the experimental method of 
proving all things, was the touchstone of the verity of his induc- 
tions. " It is the glory of God to conceal a thing," said the wise 
Hebrew monarch ; " but the honour of kings," he added, " is 
to search out a matter." Kings in the realms of Science are 
for ever searching out the hidden things which it is the glory 
of the Creator to conceal, and their discovery but adds to the 
glory of concealment. 
Located in the principal town of the Departement du Nord, 
one of the chief industries of which is the production of alcohol 
from grain and beet-root, Pasteur resolved to devote his attention 
to the study of fermentation, not only with a view to solving the 
problems in connection with it, but also to apply the knowledge 
gained to a useful purpose. He studied the spontaneous fermen- 
tation of milk (lactic fermentation), in which a portion of the sugar 
■p. J is transformed into lactic acid; and, as a conse- 
Bacterium quence, he found himself opposed to the opinion of 
Lar.tis (the the few observers who, detectirig living organisms 
Lactic Fer- in certain fermentations, imagined the presence of 
menl).'* these was accidental, and instead of being favourable 
to the process, was really detrimental to it. He con- 
stantly found an extremely minute microscopical 
living organism, of well-defined form, consisting of 
' little rods, constricted in the middle, and multi- 
plying by dividing across (fission), each portion forming another 
rod, which soon underwent the same process of division, and so 
generation after generation of rods was quickly produced. Other 
inquirers had failed to observe this organism in the lactic fermen- 
tation, through imperfect manipulation and faulty preparation 
of the liquid : they having mixed chalk with the milk in order 
to keep it neutral, and employed various nitrogenous sub- 
stances — all of which rendered it impossible to distinguish the 
ferment. Pasteur happily avoided this cause of error by boil- 
* This figure, and those on pp. 50, 57, Gl, and 117, arc reproduced from 
Dr. Klein's book entitled ' Micro-urgauitms and Disease,' by permission of the 
publishers, Messrs. Macmillan and Co. 
