2 94 Mayow 



septuQi is thus made more nearly plane, the heart as 

 a whole is carried to the left, as may be seen in the 

 figure. For when a motion has been once impressed 

 on the heart it continues for some time, in accordance 

 with the nature of projectiles ; and thus it comes 

 about that the heart brought to the left, strikes the 

 left side of the chest forcibly, though the greater 

 thickness of the wall of the left ventricle, its more 

 powerful pulse, not to mention its very shape, so 

 different from that of the right ventricle, contribute 

 in no small degree to this effect. And to these 

 things I may add that the spiral fibres in the walls of 

 the left ventricle are so arranged that, when they 

 contract, the heart is twisted by them, so that the 

 right ventricle is carried backwards towards the spine, 

 and the left somewhat forwards towards the chest, so 

 as to strike it. 



From what has so far been said it follows, that if 

 the blood cannot escape with suflScient freedom from 

 the ventricles of the heart, on account of an obstruc- 

 tion of any sort whatever, either of the pulmonary 

 vessels or of the great artery, it cannot but be that, 

 as the heart violently contracts to expel as far as may 

 be the load of blood, the walls of the ventricles are 

 widely distended into a ball, and in consequence the 

 heart is dashed violently against the chest ; so that 

 the ribs are sometimes pushed out by its blows. 

 And it may be supposed that palpitation of the 

 heart, especially when long continued, proceeds from 

 this cause ; for although in this affection the pulsation 

 of the heart is very violent, still the pulse of the 

 arteries at the wrist is usually quite languid ; as has 

 been observed by others as well as by ourselves. 

 Besides, it points in this direction that in the bodies 

 of persons who have died of palpitation of the heart, 



