Excerpt from Physiological Reviews, Vol. 1 The other contribution which we regard as fundamental for the present conception of the heart beat, is the series of physiological observations which indicates that recently discovered anatomical structures in the heart have the function of initiating and distributing the impulse or excitation to the contractile muscle tissues of the auricles and ventri cles. Since much of the work contributary to this conception of cardiac activity is of comparatively recent date, we consider it proper to discuss it in some detail under separate headings. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.