. A text-book of animal physiology, with introductory chapters on general biology and a full treatment of reproduction ... Physiology, Comparative. Fio. 311. Fio. 312. FtG. 211.—Microscopic appearances of fibers from the heart. The cross-striee, divisions (brandling), and junctures are visible (Landois). Fig. 812.—Muscular flber-cells from the heart. (1 x 425.) a, line of juncture between two cells; b, c, branching cells. tetanic contraction, certainly not the heart of the mammal; so that it is customary to term the cardiac contraction peristaltic. If this view be correct, how could there be a
. A text-book of animal physiology, with introductory chapters on general biology and a full treatment of reproduction ... Physiology, Comparative. Fio. 311. Fio. 312. FtG. 211.—Microscopic appearances of fibers from the heart. The cross-striee, divisions (brandling), and junctures are visible (Landois). Fig. 812.—Muscular flber-cells from the heart. (1 x 425.) a, line of juncture between two cells; b, c, branching cells. tetanic contraction, certainly not the heart of the mammal; so that it is customary to term the cardiac contraction peristaltic. If this view be correct, how could there be a sound produced by muscular contraction alone ? To this it has been replied that the sudden tension of the ventricular wall when tightened over the blood may give rise to vibrations that account for the sound; and recent investigations have shown that the vibrations that give rise to the sound emitted by a contracting skeletal muscle may be fewer than was once supposed. The statement that a sound may be heard from the excised ventricle under the circumstances above mentioned has not been denied; but its source has been traced to the action of the heart wall against the stethoscope—i. e., some believe the sound to be, in this case, of extrinsic origin. Most physicians would be very loath to abandon the view that the valves are always to be taken into serious account as a factor in the causation of the But, looking at the whole question broadly, is it not unrea- sonable to explain the sound resulting from such a complex act as the contraction of the heart and what it implies in the light of any single factor ? That such narrow and exclusive views should have been propagated, even by eminent physiologists, should admonish the student to receive with great caution ex-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble t
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