MOTION OF THE HEART AND BLOOD 



not four movements distinct in time, but only in 

 space. The two auricles beat together and so do the 

 two ventricles, so that there are four distinct move- 

 ments in space, but only two in time. This happens 

 as follows. 



Two sets of movements occur together, one of the 

 auricles, another of the ventricles. These are not 

 simultaneous, but that of auricles precedes that 

 of the rest of the heart. The movement seems to 

 start in the auricles and to spread to the ventricles.'^ 

 When the heart slows in approaching death, or in 

 fishes and cold-blooded animals, there is a pause 

 between the two movements, and the heart seems 

 to respond to the motion as if aroused, sometimes 

 quickly, sometimes slowly. At length, nearly dead, 

 it fails to respond to the motion, and it stirs so ob- 

 scurely that the only signs of motion are pulsations 

 of the auricle, as if just lightly nodding the head. 

 The heart thus stops beating before the auricles, 

 and the latter may be said to outlive it. The left 

 ventricle stops beating first of all, then its auricle, 

 then the right ventricle, and, finally, as indeed 

 Galen noted, when all the rest is quiet and dead, the 

 right auricle still pulsates. Life, therefore, seems 

 to remain longest in the right auricle. While the 

 heart gradually dies, it sometimes responds with a 



^ The first clear statement on the problem of the origin and conduc- 

 tion of the heart beat. For a recent comprehensive discussion of this 

 question see Eyster, J. A. E, and Meek, W. J., Physiological Reviews, 

 i: I (1921). 



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