68 ON THE MOTION OF THE BLOOD. 



113. The systole of the ventricles, upon which is 

 said to be spent one third of the time of the whole ac- 

 tion of the heart, is performed in such a way, that their 

 external portion is drawn towards their septum, and 

 the apex of the heart towards the base. * This at first 

 sight seems disproved by the circumstance of the apex 

 striking against the left nipple and consequently ap- 

 pearing elongated, a circumstance, however, to be 

 attributed to the double impetus of the blood flowing 

 into the auricles and expelled from the ventricles, by 

 which the heart must be driven against that part of the 

 ribs. (A) 



114. The impulse imparted by the heart to the blood, 

 is communicated to the arteries, so that every systole 

 of the heart is very clearly manifested in those arteries 

 w r hich can be explored by the fingers and exceed I of 

 an inch in diameter, and in those also whose pulsation 

 can be otherwise discovered, as in the eye and ear. 

 The effect upon the arteries is called their disastole, 

 and is correspondent and synchronous with the systole 

 of the heart. 



115. The quickness of the heart's pulsations during 

 health varies indefinitely; chiefly from age, but also 

 from other conditions which at all ages form the pecu- 

 liar health of an individual ; so that we can lay down 

 no rule on this point. I may, however, be permitted 

 to mention the varieties which I have found in our 

 climate f at different ages, beginning with the new-born 



r ,,* Consult Ant. Portal, Memoir en aur la Nature iff le Traitement de plusieurs 

 Maladies. T. ii. 1800. p. 281. 



f My observations differ but little from those made by Hcberden in England, 

 Mcd. Trans, vol. ii. p. 21 sq. 



