Ever since the introduction of the conception
of circus movement in auricular fibrillation and
auricular flutter and the introduction of quinidine
for their treatment, the refractory period has
assumed an increasingly important ró le in understanding
the pathology and the therapeutics of many disorders
of cardiac contraction. A thorough knowledge
of its physiology, therefore, is of great importance.
Unfortunately, however, comparatively little has been
done in this direction. The object of the present
investigation is to study the refractory period of
the frog's heart under several experimental conditions
and its relation to other phenomena associated with
cardiac contraction. The subject matter will be
considered under the following headings:-
I. The effect of variations in the diastolic
filling on the durations of the refractory
period and of the mechanical response.
II. The effect of various ions on the duration
of the refractory period and on the mechanical
III. The effect of rate of stimulation on the
durations of the refractory period and of
the mechanical response.
IV. The relation of the refractory period to
other phenomena associated with contraction.