MOTION OF THE HEART AND BLOOD 



1. The heart is lifted, and rises up to the apex, 

 so that it strikes the chest at that moment, and the 

 beat may be felt on the outside.^ 



2. It contracts all over, but particularly to the 

 sides, so that it looks narrower and longer. An 

 isolated eel's heart placed on a table or in the hand 

 shows this well, but it may also be seen in the hearts 

 of fishes and of cold-blooded animals in which the 

 heart is conical or lengthened. 



3. Grasping the heart in the hand, it feels harder 

 when it moves. This hardness is due to tension, 

 as when one grasps the fore-arm and feels its tendons 

 become knotty when the fingers are moved. 



4. An additional point may be noted in fishes and 

 cold-blooded animals, as serpents and frogs. When 

 the heart moves it is paler in color, but when it 

 pauses it is of a deeper blood color. 



^ The first clear statement of the significance of the apex beat. 

 In the physiological analysis of the events of the cardiac cycle in an 

 intact subject, this is an important reference point, marking, as Harvey 

 noted, the moment of ventricular systole and emptying. The graphic 

 analysis of the cardiac cycle was especially developed by E. J. Marey 

 (1830-1904), La Circulation du Sang, Paris, 1881, and was made 

 possible by the methods of recording by kymograph initiated by Carl 

 Ludwig (1816-1895). 



This is the first of that remarkable series of extraordinarily acute 

 observations on the motion of the heart and blood so simply and clearly 

 reported by Harvey in this book. Compare the number and quality of 

 these observations and the clear interpretation of their significance 

 as made by him, with the stumbling, vague, and incomplete ideas 

 on the matter as given by Servetus (1510-1553), Columbus (1516- 

 1559)» Ruini (died before 1598), Caesalpinus (1524-1603), and others 

 for whom credit is claimed for discovering the circulation, and you will 

 agree that to Harvey alone should be given the honor of first realizing 

 the full truth, and of demonstrating it to the world. 



I29] 



