PLATE 1 
EXPLANATION OF FIGURES 
1 Bundles that radiate from the septal raphe in the right surface of the atrial 
septum of a human heart. The endocardium has been removed. 
2 Bundles that radiate from the septal raphe in the left surface of the atrial 
septum of a human heart. The endocardium has been removed. : 
1, interatrial band A.V.N., atrioventricular node 
2, external bundles of right atrium A.V.R., atrioventricular ring 
3, right anterior crest /0S., coronary sinus 
4, right posterior crest I.V.C., inferior vena cave 
5, intercaval bundle M.O., mitral orifice 
6, superior vena caval bundles O.F., oval fossa 
7, right leaf of septum secundum P.A., pulmonary artery 
8, right leaf of septum primum P.M., pectinate muscles 
9, musculature of the coronary sinus  P.V., pulmonary vein 
10, left anterior crest R., raphe 
11, left posterior crest R.A., right atrium 
12, septopulmonary bundle S.A.N., sino-auricular node 
13, left leaf of septum secundum S.V.C., superior vena cava 
14, left septoatrial bundle T.O., tricuspid orifice 
15, left leaf of septum primum Vent., ventricle 
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