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Ceoonian Lecture. — Upon the Motion of the Mammalian Heart. 



By Thomas Lewis. 



(Eeceived May 1, 1917.) 



In these days when Europe is ablaze from end to end and our armies are 

 fighting to regain that freedom and peace which a few years back enabled us 

 undisturbed to pursue our search for knowledge, I wish that this lecture 

 could deal with some problem which affects the health of our troops. But 

 though engaged for some while with my fellow workers upon problems of this 

 kind, I am unable to deliver the lecture in this form. Were I to attempt it 

 with the material at my disposal, it would not be compatible with the 

 traditions of this lectureship to which you have done me the honour of 

 appointing me. As an alternative permit me to review a chapter of physiology 

 recently brought to completion and one which we may fairly claim to have 

 been compiled in chief part by workers in this country. 



Three hundred years have passed since William Harvey, our fellow 

 countryman, preached the doctrine by which his name has been immortalised. 

 In his book ' De Motu Cordis,' that famous model of unclouded thought and 

 of scientific reasoning, he wrote of the mammalian heart in these words : — 



" First of all, the auricle contracts, and in the course of its contraction 

 throws the blood into the ventricle, which being filled, the heart raises itself 

 straightway, makes all its fibres tense, contracts the ventricles, and performs 

 a beat, by which beat it immediately sends the blood supplied to it by the 

 auricle into the arteries ; these two motions, one of the ventricles, another of 

 the auricles, take place consecutively, but in such a manner that there is a 

 kind of harmony or rhythm preserved betweeti them." 



It is that sequence of movement, it is that harmony or rhythm of which. 

 Harvey wrote, that forms the subject of this lecture. 



Our knowledge of the heart's movements progressed but slowly from the 

 time of Harvey's discoveries. In the days of Albrecht Haller, the Swiss, the 

 movement of the heart was described as peristaltic and was likened to that 

 seen in portions of the alimentary tract. Guided by observations upon cold- 

 blooded vertebrates, physiologists regarded the movement as a muscular wave, 

 originating in the neighbourhood of the sinus venosus and passing over the 

 chambers of the heart in regular order. But when it became known that the 

 system of the ventricular contractions may in certain circumstances become 

 independent of the auricular contractions this view was largely abandoned. 



In the middle of the last century collections of ganglionic nerve cells were 



