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474 MODERN TIMES.
application of the ear to the body of the patient, since the
time of LAENNEC, who introduced the use of Ihe stethoscope
or mediate auscultation, it became a method systematically
and constantly used as an aid to diagnosis. It became
well-nigh indispensable for examining cases of pulmonary
or cardiac disease being here the most important, at times
the only available, aid to diagnosis.
But other departments of medicine also owed it much;
thus LEJUMEAU DE KERGARADEC and soon after him
MAYOR discovered the sounds of the foetal heart while
auscultating the abdomen of a pregnant woman, and in this
way furnished us with a way of recognizing the presence of
life in the foetus.
Besides these physical means of research to which
must be added mensuration and the use of the clinical
thermometer—a method elaborated in modern times chiefly
by WUNDERLICH—the advance of the art of diagnosis waslargely
contributed to by chemistry and microscopy.
The existence and the severity of many diseases as well
as their aggravation or abatement can be certainly affirmed
only by the chemical proof that definite substances found
in certain excretions—such as albumen or sugar in the
urine—are either contained in a certain proportion or show
a tendency to increase or to diminish in quantity as the
case may be. The chemical analysis of pathological products
acquired high importance in the study of diseases;
particularly in reference to the theory of toxic agencies.
And in no less degree was 'microscopical research in
many cases entitled to respect, since it gave information of
the presence of histological elements of a certain kind,
which justified certain conclusions concerning the nature
of the disease under investigation. A careful observation
of all the symptoms and a scrupulous consideration of all
the conditions bearing on the case constituted the necessary
and proper preliminary to every diagnosis.
The post-mortem appearances and their bearings upon
the symptoms during life were, with a similar object, sub-