THE CIRCULATION. 



281 



The protrusion of the point of the heart in contraction has been 

 variously regarded ; first as an elongation of the cone formed by the 



FIG. 62. 



FIG. 63. 



BULLOCK'S HEART, anterior view, CONVERGING SPIRAL FIBRES AT THE APEX OF THE 

 showing the superficial muscular HEART. The direction of the arrows indicates that of 



fibres. the rotating movement of the heart at the ventricular 



systole. 



left ventricle, and secondly, as a movement of the whole heart, due to a 

 recoil from the blood expelled from it under pressure, or to a reaction 

 of the distended arteries at its base. Many of the earlier observers 

 (Galen, Yesalius, Harvey, Riolanus, Borelli, Winslow) found the longi- 

 tudinal diameter of the heart increased at the moment of systole, and 

 its transverse diameter diminished. Pennock and Moore,* in 1839, in 

 a series of experiments on sheep, calves, and horses, also observed an 

 elongation, the extent of which they measured with a graduated rule. 

 On the other hand some of the earlier, and nearly all the more recent 

 writers of eminence (Lower, Haller, Longet, Carpenter, Flint, Ranke, 

 Chauveau, Burdon-Sanderson) are of opinion that the heart shortens 

 during systole, beinu 1 diminished in both its longitudinal and trans- 

 verse diameters. In our own observations we have always seen reason 

 to admit that the forward movement of the apex is due to an elonga- 

 tion of the heart at the moment of systole. This is not easily percep- 

 tible in a front view, owing to the prominent action of the right ven- 

 tricle on the anterior surface of the organ. But if the heart be tilted 

 upward and viewed from its posterior surface, formed mainly by the 

 left ventricle, while its base is firmly held by the fingers placed upon 

 the great vessels, at every contraction its sides will be seen to approxi- 

 mate each other, and its point to protrude ; that is, its longitudinal 

 diameter is increased, and its transverse diameter diminished. The 

 end of the finger in contact with the apex is forcibly thrown upward 

 by the contracting ventricle, and a light rider of paper placed on the 



* Medical Examiner. Philadelphia, 1839, No. 44. 



