A reference handbook of the medical sciences, embracing the entire range of scientific and practical medicine and allied science . Fig. 729,—Simultaneou.* Photograra of a Single Beat (BlackLine) and of the Accompanj-ing Electrical Change, indicated bythe level of the black area, which showB the varying level of mercuryin a capillary electrometer. I. First phase, base negative to apex;II, second phase, apes negative to base. (Waller.) finally, that the contraction ends by disappearingfirst at the apex. It evidently follows the recurrentpath of the superficial oblique fibers beginning andending


A reference handbook of the medical sciences, embracing the entire range of scientific and practical medicine and allied science . Fig. 729,—Simultaneou.* Photograra of a Single Beat (BlackLine) and of the Accompanj-ing Electrical Change, indicated bythe level of the black area, which showB the varying level of mercuryin a capillary electrometer. I. First phase, base negative to apex;II, second phase, apes negative to base. (Waller.) finally, that the contraction ends by disappearingfirst at the apex. It evidently follows the recurrentpath of the superficial oblique fibers beginning andending at the auriculoventricular groove. Anotherdeduction drawn from the electrical phenomena of theheart is that its contraction is comparable to a simplemuscle twitch and is not to be regarded as a sum-mated or tetanic contraction. (6) Changes in the Form and Position of the Heart.—In diastole the heart can hardly be said to possessa definite shape of its own, although it is frequentlydescribed as a hemispheroid with a rounded apex andsomewhat flattened anterior and posterior Fig. 730.—Diagrammatic Curve of the .\etion Currents ofthe Human Heart. (Einthoven.) R, Beginning of ventricularcontraction: S, apex negative to base: T, third phase, base negativeto apex. The small diphasic variations represented by P and Qare caused by the auricular systole. On account of its soft, flabby condition its shapechanges according to the position of the body underthe influence of its own weight. Xot so in systole;the heart then becomes hard and rigid and its shapeapproaches that of a regular cone with a circularbase. The changes in the three diameters duringthis transition must depend on its previous form indiastole. Under normal conditions in which theheart is supported by the lungs as by an elasticcushion, there is probably no extensive flattening inany one plane. In this case entrance into systolewould involve a shortening in all directions while the ^ REFERENCE HANDBOOK OF THE


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Keywords: ., bookauthorbuckalbe, bookcentury1900, bookdecade1910, bookyear1913