vital action or a simple mechanical elasticity, may contribute in part to the production of the second sound. About the time lhat Mr. Turner's views were published, Dr. Barry published a Thesis containing a different hypothesis. He maintained that the sounds are produced, not by the contraction, but by the dilatation of the cavities. According lo his views, the first sound is occasioned by the diastole of the auricles, the second by that of the ventricles. Since lhat period an able discussion

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... s been continued in the different periodicals, in which Drs. Williams, Hope, Corrigan, Haycraft, Pigeaux, Stokes, and several others, have participated. Dr. Elliotson, of ihe London University, has afforded much valuable practical information on this subject ; and many pertinent remarks from Dr. James Johnson have, from time to time, appeared in the London Medico-Chirurgical Review. Various new hypotheses have been promulgated by the different gentlemen who have engaged in this discussion, and the subject can by no means be considered as yet clearly settled. Dr. Corrigan maintains that the impulse against the side is occasioned by the diastole of the ventricles, " being dependent on the force with