Page:The Harveian oration 1905.djvu/91

 well as for studying arterial pulsation and certain other vascular phenomena. Special tactile signs appreciated by palpation, associated with the heart or vessels, are also of much diagnostic value. The introduction of percussion, and its application to the study of præcordial dulness, as well as of that due to aneurysm in internal cavities, was a distinct clinical gain, and this method often gives decided help in diagnosis. Personally, however, I venture to differ from some eminent authorities in their estimate of the reliance to be placed on percussion-signs in relation to enlargement of the heart, even with the aid of special plessors and pleximeters, and at any rate it is always well to be on guard against possible sources of error. Since the invention of the stethoscope, auscultation has, for obvious reasons, come more and more to the front, and is now generally and rightly regarded as par excellence the method of physical examination most adapted for the circulatory system. Indeed, in a large number of cases it is the only means by which a positive diagnosis can be arrived at. Let it never be forgotten, however, in relation to the heart, that auscultation is not merely of use for the detection of "cardiac murmurs," or pericardial friction, a mistake by no means uncommonly made, but that the ordinary sounds should also be borne in mind and carefully studied. It may, further, be of decided help in appreciating the rhythmic action of the heart, and