Page 729 - My FlipBook

ETIOLOGY OF CARIES. 739
difficult Avith which the intelligence of man has had to grapple, and was
evidently not understood by those who conceived the fermentation
hypothesis for the origin of caries. It was, indeed, known that many
substances give rise to acids of various kinds during the process of
decomposition by fermentation or putrefaction, but what was the modus
operandi was an open question that was debated at that day only by
the most astute chemists. The molecular-motion theory of fermenta-
tion and putrefaction cannot be said to have been fully developed until
1840, when Justus Liebig wrote his Chemistry in its AppJication to
Af/riculture and Physiology as a report to the British Association for
the Advancement of Science. The subject had, indeed, been under dis-
cussion for several centuries without the development of any theory for
the rational explanation of the observed phenomena upon which the
learned men of the world could agree. This theory had been imper-
fectly shadowed forth for many years, but it seemed to require the
genius of Liebig to systematize and place it before the world of thought
in tangible form. Yet even before the work was completed an antag-
onist had arisen in the germ theory of these processes, growing out of
the discovery of the yeast-plant by Schwann in 1838 ; and these two
rival theories have struggled with each other for the mastery almost up
to the present time, and there are perhaps many who will assume that
the struggle is still going on. During this time it is but fair to say
that there has been no theory of fermentation that has been fully
accepted. The full explanation of caries of the teeth re(]uired an
acceptable explanation of the processes of fermentation, and the learn-
ing of the period failed to afford this. For this reason the subject has
always been enveloped in a degree of obscurity that has rendered all
attempts at explanation unsatisfactory.
In this condition of the minds of men it is cjuite natural that other
modes of explanation should be sought. And in the last half century
almost every source of knowledge has been questioned with the hope
of obtaining an answer, but none has been vouchsafed ; for after
threading the labyrinth of the theories propounded—and these have
been many—the questioner has again turned back to the theory of fer-
mentation with all its mystery and uncertainty. When Ave review the
literature of the subject we find that since the time of Robertson
and Regnard this explanation of the subject has never been entirely
lost sight of. It must be confessed, hoAvever, that it has often been
presented in so confused a manner, and so mixed with other theories,
that its best friends could Avith difficulty recognize that a A'estige of it
remained.
NoAv, after the work of so many years has been added in the effort
to explain the nature of fermentation, and Avhen the labors of such men
as ScliAA'ann, Schroeder, Lister, Koch, Klein, and Miller haA^e made us
acquainted Avith the agency of micro-organisms in the processes of fer-
mentation and putrefaction, this seems to be regarded as another of the
ncAv theories which haA'e sprung to the front demanding a hearing. If
any ha\'e this thought, I wish to say that it is a misconception. It is
but a further explanation of the old theory as propounded by Robertson
and Regnard—an explanation of the processes of the fermentation by