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40 as possible emptied of blood ; and the con- clusion which the authors come to is that the heart of the dog, when removed from the body and emptied of blood, still pro- duces a sound during the systole of the ventricles which is not essentially different from that which is recognised as the normal first sound of the heart. The authors add, however (p. 85), that they do not think these experiments entirely exclude the possibility of the tension of the auriculo-ventricular valves entering as a factor into the produc- tion of the first sound ; and hereby they would be guarded from coming into con- tradiction with most English authorities — as for example, Dr. Walshe (Diseases of the Heart, 3rd ed. 1862, p. 62). Dr. Guttmann, however, in a paper of no great length, but of considerable merit, published subsequently to the one just mentioned, and in Virchow's Archiv for 1869, points out with much acuteness what, when once pointed out, is ever thereafter obvious — viz. that it is, in the nature of things, impossible, with all possible precautions in the way of emptying the heart of blood, to empty the complex