On some Points in the Innervation of the Mammalian Heart

ALTHOUGH a large amount of work has been done on the nerves acting on the mammalian heart, yet it is only in a few cases that the method of direct registration of the movements of auricles and ventricles has been used (McWilliam', Roy and Adami2). This fact is probably largely responsible for the numerous gaps in our knowledge of the subject, as compared with the exact knowledge we have of the actions of the nerves in the cold-blooded animals, frog, tortoise, etc. (Gaskell3, Heidenhain and others). In a former paper4, we showed that the electrical events accompanying the contraction of the mammalian heart were exactly analogous to those occurring in the frog and tortoise; and we started this present research with a view to determining how far this analogy extended to the innervation of the heart in these two classes of animals, and especially with regard to the influence of the two sets of cardiac nerves on conduction between auricles and ventricles. After we had written the rough draft of this paper, an abstract of a communication by Roy and Adami to the Royal Society has appeared5, in which these authors, using their ingenious myocardiograph to record the ventricular and auricular contractions, point out that both vagi and accelerator nerves may affect rhythm or force or both together. As will be seen, our work confirms most of their results, so far as we treat of the same subjects. They have not, however, considered the influence of the nerves on