9 6 



THE MOVEMENTS OF THE HEART. 



The frog's heart is less readily exhausted than that of the higher vertebrates.- 

 Serum-albumin, alkaline salt-solutions of blood, or of milk, made slightly viscid 

 with albumin or gum arabic and sattirated with oxygen, are capable of main- 

 taining the activity of the heart for a long time. 



Pathological. In the presence of so-called sclerosis of the coronary arteries 

 in old age there occur acute or chronic attacks of cardiac disability. Weakness 

 of the heart, alterations in rhythm and frequency (to 8 in a minute), constitute, 

 together with dyspnea, syncope, stasis, attacks of pulmonary edema, the most 

 characteristic phenomena ; and they may terminate in death from so-called heart- 

 failure. In a case of occlusion of the left coronary artery in a man Hammer 

 saw the pulse fall from So to 8, the beats being interrupted by spasmodic vibra- 

 tion. 



THE MOVEMENTS OF THE HEART. VARIATIONS IN TONE. 



Method. In addition to direct observation, the kinematograph may be used 

 to great advantage for recording and projecting the movements of the heart, par- 

 ticularly at a slow rate. 



S.a.-D.v. 



D.a.-S.v. 



FIG. 25. Diagrammatic Representation of the Auricular Systole with Ventricular Diastole, and of Auricular 



Diastole with Ventricular Systole. 



The movement of the heart is appreciable as alternate contraction 

 and relaxation of the heart- walls. The entire motor phenomenon 

 designated the cardiac cycle consists of three parts: contraction 

 of the auricles (auricular systole); contraction of the ventricles (ven- 

 tricular systole), and the pause, during which the auricles and the ven- 

 tricles are relaxed (diastole). During the contraction of the auricles the 

 ventricles are at rest, during the contraction of the ventricles the auricles 

 are relaxed. The following phenomena can be noted successively during 

 a cycle of the heart : 



(A) The blood streams into the auricles, which in consequence are- 

 distended. The cause for this resides in: 



