Report on the progress of human anatomy and physiology in the year 1844-5 / [Sir James Paget].

  • James Paget
Date:
1846
Catalogue details

Licence: Public Domain Mark

Credit: Report on the progress of human anatomy and physiology in the year 1844-5 / [Sir James Paget]. Source: Wellcome Collection.

    12/64 (page 12)
    CIRCULATION. Action of the heart. Dr. Mitchell,* in a case of ectopia cordis, watched the movements of the heart for an hoar and fifty minutes. The pulsations were twenty-five in a minute before the separation of the umbilical cord ; after it they fell to twenty, and then to seventeen. After the auricles were distended with blood they emptied themselves by a gentle flowing1 motion, and imme¬ diately after this the ventricles contracted. The effect of the ventricular con¬ traction was to shorten the heart from base to apex, and to cause a consider¬ able bulge or projection in the centre, giving rise to an evident elevation of the fingers when laid on it. The apex of the heart was not elevated. After the ventricular contraction the heart appeared quite flaccid and relaxed, although it was evident that the ventricles were not emptied. Volkmannf has discussed the relation of the movements of the heart to the nervous system ; and, to prove that they do not depend on the brain and spinal cord, he adduces the fact that they continue after the heart is cut out, while all the rythmical movements which do depend on the brain and cord, such as those of respiration and the lymph-hearts, cease as soon as their connexion with parts of those nervous centres is destroyed. He supposes, therefore, that the movements of the heart depend on the immanent power of the sympa¬ thetic nerve-fibres and ganglia in its substance. His experiments show, that if the auricle and ventricle, while pulsating rythmieally and in harmony in a fresh frog’s heart, be suddenly separated from each other, though they may both continue to pulsate they will not pulsate in harmony. And when the ventricle is divided by incisions carried through nearly its whole length, some of its portions will continue to pulsate spontaneously and rythmieally, while others, just as large, will only move when irritated. He thinks that this shows that, in the former, central organs remained from which impulses for movement might proceed, while in the latter there were no such central organs or ganglia. He concludes, therefore, that the ganglia in the heart are so many central organs, or points from which motor impulses flow out, and that they are suited for action in concert by connecting nerve fibres, forming altogether a system so arranged as to produce, in regular series, the successive contractions of the muscles of the heart. This theory coincides in many points with that of Kurschner, alluded to in the last report; and he holds that the auricles are the parts to which the reflex influences of the ganglia are always first directed, and that the contraction of the ventricles is the consequence of the contraction of these. In evidence of this he says, that whatever part of a heart, when cut out but still irritable, is irritated, the consequent contraction always begins in the auricle. [But it is certainly not always so : I have many times tried the experiment in cut out turtles’ hearts, and have always found that the contraction begins at the part irritated and thence extends over all the rest.] Valentin,}; also, has made experiments on the same question, but he doubts whether the rythmical con¬ tractions of the heart are dependent wholly on its nervous system, and not in part on the mechanical arrangement of its fibres; since, he says, the con¬ tinuance of rythmical movements is observed only in those pieces of the heart established view that the rigor is due to the contraction of the muscles. 5. Harting, Histologische Aaanteekeningen; in the Tijdschrift already referred to. Besides the papers on the muscles, lens, and nerves of which an account is here given, the essay contains remarks on the milk-corpuscles, the action of sublimate on the blood-corpuscles, and other questions of the anatomy of tissues. The continuations of the admirable works of Dr. Sharpey, in the new edition of Quain’s Anatomy, of Dr. Todd and Mr. Bowman, in their Physiological Anatomy, and of Mulder, in his Physiol. Scheik- unde, are also important contributions to the recent history of general anatomy. * Dublin Journal of Med. Sciences, Nov. 1{I44. t Muller’s Archiv, 1U44, Heft iv, p.424. ; Handb. der Physiologic, Bd. ii, p. 7(i7.