39 it be to be observed under physiological conditions, may be exaggerated into con- siderable prominence in disease entailing contraction of the auriculo-ventricular ori- fices, and may then make itself known by a presystolic murmur. I should now be glad to draw attention shortly to a few memoirs which have ap- peared comparatively recently, and which treat of matters of considerable interest, not merely as scientific problems, but also as practical questions. First among these I would name the paper which appears in the third volume of Professor Ludwig's 'Ar- beiten/ 1868 (having previously appeared in vol. xx. of Bericht Math.-Phys.-Klass. K. S. Gesellsch. Wissensch., Leipzig), by Professor Ludwig himself and Dr. Dogiel. In this paper we have a number of experiments recorded as performed with the hearts of dogs removed from the body, and as nearly will be accepted as correct. It runs thus (Diseases of the Heart and Great Vessels, 3rd ed. 1862, p. 65): 'In the normal state the blood enters the ventricles from the auricles with a curi'ent so calm as to prevent audible sound from being thereby produced in the former cavities.'
