DISEASES OF THE HEART 459 



scope in human practice, by the application of the ear to the part where the 

 lower animals are concerned. 



The object of this form of examination is to distinguish any abnormal 

 sounds which may exist in connection with the beats of the heart. These 

 sounds can only be distinguished by the expert who is familiar with the 

 healthy sounds, which may be described as far as it is possible to describe 

 them in words as follows: First, there is a sound which is believed to 

 be produced by contraction of the ventricles. This is called the systolic 

 sound, and it is also distinguished as a long sound, the term being used, 

 of course, comparatively. This systolic sound is followed by a short 

 interval of silence, which is succeeded by the second, described as the 

 diastolic sound, which occurs when the ventricles cease to contract, and 

 the valves guarding the pulmonary vessels and the aorta close. The 

 diastolic sound is followed by a rather longer silence than that which 

 succeeds the first, and then the systolic or first sound recurs. The duration 

 of the sounds and intervals is expressed by dividing the whole period 

 occupied by the series into ten parts, and then subdividing as follows: 

 Systolic sound ^, first interval y^, diastolic sound -5^, and second 

 interval - x %. The actual character of the sounds as they strike the ear 

 has been expressed by Dr. C. J. B. Williams by the words "lub-dup". Very 

 little difficulty would be experienced in rendering the ear accustomed to 

 the normal sounds of the heart, but it must be clear that an acquaintance 

 with the abnormal sounds and their meaning could only be acquired by 

 long practice with the assistance of a competent instructor. The most that 

 the tyro could hope to achieve in this direction without such assistance 

 would be the recognition of a change from the normal sound of the heart or 

 its large vessels, and he would arrive at the knowledge simply from the 

 observation that the normal sound with which he had rendered himself 

 familiar had undergone certain modifications. 



The expert, in making an examination, not only realizes the fact that 

 there is a change from the normal sounds to the abnormal, but he dis- 

 tinguishes also the seat and cause of the abnormal murmurs; for example, 

 variations as to the intensity of sounds, whether increased or diminished, 

 alteration with regard to pitch and clearness of the systolic sounds, will 

 inform him as to the condition of the valves and walls of the heart. A 

 very clear, sharp, high-pitched, systolic sound will be more commonly 

 heard in cases of anaemia, or extreme debility; again, alterations in the 

 duration of the sound give important information as to the condition of the 

 heart. In dilatation of the ventricles, with increase in the thickness of the 

 walls, the systolic sounds will be prolonged, and the diastolic sound will 

 probably be much shortened and very much obscured; whereas, in dilata- 



