. Electro-physiology. Electrophysiology. 400 ELECTRO-PHYSIOLOGY CHAP. of the heart-muscle. It is evident that these facts coincide with Hermann's theory, according to which a point of the muscle must remain negative as long as the excitatory (or contraction) process continues. Accordingly, we should expect the surface of the ventricle to be isoelectric during the period qf systolic contraction, as actually appears from the experi- ments of Burden-Sanderson and Page. If, in the accompanying Fig. 127, (a, x) is the spot excited, (F) and (w) the two points of the ventricle led off, there will fol
. Electro-physiology. Electrophysiology. 400 ELECTRO-PHYSIOLOGY CHAP. of the heart-muscle. It is evident that these facts coincide with Hermann's theory, according to which a point of the muscle must remain negative as long as the excitatory (or contraction) process continues. Accordingly, we should expect the surface of the ventricle to be isoelectric during the period qf systolic contraction, as actually appears from the experi- ments of Burden-Sanderson and Page. If, in the accompanying Fig. 127, (a, x) is the spot excited, (F) and (w) the two points of the ventricle led off, there will follow on each excita- tion a rapid electrical variation' (lasting only a few 1OO sec.), in the direction of a current from the b. m m •H: ' • > . ' Fio. 127.—«, b, Diagrammatic representation of the electrical variation in an artificial cardiac contraction (Burdon-Sanderson and Page). The continuous line corresponds to the process of negativity at the electrode nearest the seat of excitation. The dotted curve, on the contrary, gives the negativity at the more remote contact. The middle line marks the time in ^5 sec. (1'N) corresponds with the negative, (VP) with the positive variation on Bernstein's rheotome. seat of excitation, succeeded by a longer period (1 — 2"), during which no current is indicated by the galvanometer; this is followed by an opposite phase of deflection (positive variation) which is much weaker and more prolonged than the initial " negative" variation. The interval separating the two phases corresponds exactly with the duration of the ventricular contraction, so that the one (negative) phase of the action, current marks the beginning, the other (positive) the end of the excitation (contraction) of the muscle. The first phase of the action current obviously corresponds with the very short period during. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - colora
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