618 



HEART. 



Williams that we owe the first direct experi- 

 ments in support of it. In one experiment he 

 ascertained that the second sound was louder 

 over the origin of the large arteries than over 

 the surface of the ventricles, while it was the 

 reverse with the first sound; that pressure upon 

 the origin of the aorta and pulmonary artery 

 suspended the second sound ; and that the 

 second sound disappeared after the auricles 

 had been laid open, although the first conti- 

 nued. In a second experiment* we find the fol- 

 lowing observations stated : " Observation 6. 

 A common dissecting hook was passed into 

 the pulmonary artery, and was made to draw 

 back and thus prevent the closure of the semi- 

 lunar valves; the second sound was evidently 

 weakened and a hissing murmur accompanied 

 it. A shoemaker's curved awl was then passed 

 into the aorta so as to act in the same way on 

 the aortic valves. The second sound now 

 entirely censed and ions replaced by a hissing. 

 Observation 7. The hook and the awl were 

 withdrawn; the second sound returned and the 

 hissing ceased. Observation 8. The experi- 

 ment 6th was lepeated with the same result, 

 and whilst Dr. Hope listened I withdrew the 

 awl from the aorta. He immediately said, 

 ' Now I hear the second sound.' I then 

 removed the hook from the pulmonary artery ; 

 Dr. Hope said, ' Now the second sound is 

 stronger and the murmur has ceased.' " The 

 Dublin Committee have repeated and con- 

 firmed these experiments of Dr. Williams. In 

 their experiments one of the valves in each 

 artery was transfixed and confined to the side 

 of the vessel by a needle, and the second sound 

 disappeared ; on withdrawing the needles they 

 re-appeared. 



As the second sound thus appears to be pro- 

 duced by the shock of the blood upon the semi- 

 lunar valves, its intensity must, in a great 

 measure, depend upon the diastole of the ven- 

 tricle drawing part of the blood back upon 

 them, but perhaps more particularly upon the 

 elasticity of the large arteries returning suddenly 

 upon their contents during the diastole of the 

 ventricles, when the distending force of the 

 ventricles has been withdrawn. We would 

 therefore expect that the second sound should 

 be louder in those whose aorta retains its elas- 

 ticity, than in those (a circumstance sufficiently 

 common in old age) in whom, from a morbid 

 alteration of the structure of its coats, the 

 elasticity is either lost or greatly diminished. 

 This is an observation which, as far as I know, 

 has not yet been verified ; but my friend Dr. 

 W. Henderson informs me that he is positive 

 from numerous observations that the second 

 sound is louder in young than in older persons ; 

 but whether this is in the exact ratio of the 

 change upon the elasticity of the coats of the 

 large vessels he is not at present prepared to 

 say. 



* These experiments were performed upon asses, 

 in which the sensation was first suspended by a 

 dose of wourara poison and then maintaining arti- 

 ficial respiration. In this manner the heart con- 

 tinued to act upwards of an hour after the com- 

 mencement of the artificial respiration. 



BIBLIOGRAPHY. As a complete bibliography of 

 the Anatomy and Physiology of the Heart would 

 include all the systematic works on Anatomy and 

 Physiology, we shall here confine ourselves to the 

 enumeration of those works and memoirs which 

 treat exclusively or in a prominent manner of the 

 normal anatomy or functions of that organ. 



Harvey, De motu cordis, Rot. 1661. Lower 

 (Richard), Tractus de corde, &c. Lond. 1669. 

 1'echlimu (John Nicol ), Disscrtat. de fabrica et 

 usu cordis, Ricl. 1676. Hartholin (Casp.), Dis- 

 sert, de cordis structura et usu, Hafnife, 1678. 

 Charleton ( Walter), The organic structure of the 

 heart, Lond. Ib'iiS. Morton (C.), Dissert, de 

 corde, Lugd. Batav. 1683. Bellini (Laurent.), 

 Opuscula aliquot de urinis, de motu cordis, &c. 

 Lugd. Bat. 1696. 4to. Chirac (Peter), De motu 

 cordis adversaria analytica, : Montp. 1698. Fietw- 

 seiis, Nouvelles Dccouvertes sur ie ctjp.ur, Montp. 

 1706. Traite nouveau de la structure du cceur, &c. 

 Toulouse, 1715. Thebeaus, De circulo sanguinis 

 in corde, Leipsick, 1708. Ibid. De circulo san- 

 guinis per cor, Leipsick, 1759. Bttrelli (J. A.), 

 De motu aniinalium, Lugd. Bat. 1710. Wimlow, 

 Sur les fibres du coenr et sur ses valves, Mem. de 

 1'Acad. Roy. de Paris, 1711. Morgagni ( Jo.Bapt.), 

 Adversaria Anatomica, Lugd. Hat. 1723. Santo- 

 rinus, Observ. Anatomicae, Venise, 1724, cap. viii. 

 Ruysch, Epist. Anat. problemata decima de auri- 

 cularum cordis earumque fibrarum metriciam struc- 

 tura, Amsterdam, 1725. Lancisi (Jo. Mar.), DC 

 motu cordis, &c. Rom. 1728. fol. Op. Om. torn. iv. 

 1745. 4to. Walther, De structura cordis auricu- 

 larum, Leipsick, 1738, reprinted in Bailor's Dis- 

 put. Anat. torn. ii. 1747. Stvart ( Alex. ) De motu 

 et structura musculari, Lond. 1738. Examen de 

 la question si le coeur se raccourcit ou s'alonge 

 lorsqu'il se contracte, Mem. dc 1'Acad. de Paris, 

 vol. i. p. 114. 1743. Senac, Traite de la struc- 

 ture du cceur, de son action, &c. Paris, 1749. 

 torn. i. and Appendix to torn. ii. Lieutuud, Observ. 

 Anatom. sur le cceur, dans Memoires de 1'Acad. 

 de Paris, 1752-54. Hatter (Albertui), Memoires 

 sur la nature sensible et irritable dcs parties du 

 corps animal, Laus. 1756. torn. i. Ibid. Klementa 

 Physiologic, torn, i 1757. This last work, and 

 the Traite de la Structure du Cceur, &c. of Senac, 

 contain a most accurate and detailed account of all 

 that was known upon the Anatomy and Physiology 

 of the Heart before and at the time they were 

 written. Wdff (C. F.), Disscrtationes de ordine 

 fibrarum musciilarum cordis, in Acta Acad. Petro- 

 polit. 1780-1792. Abernethy (John), Observations 

 on the Foramina Thebesii of the Heart, Phil. 

 Trans. 1798. LegaUois, Dictionnaire lies Sc. Med. 

 torn. v. 1813. Gerdy(P.N.j, Journal Compl. du 

 Diction, des Sc. Med. torn. x. 1821. Recherchcs, 

 Discussions, ct Propositions d'Anatomie, Physio- 

 logic, &c. 1823. The plates given by Gcrdy in the 

 latter work have been copied by M. Jules-Cloquet 

 in his Planches d'Anat. de 1'Homme, &r. torn. iv. 

 Vaust (J. F.), Recherches sur la structure et les 

 mouvemens du ca'ur, Liege, 1821. 



Memoirs exclusively on the relative sixe of the several 

 cavities of the heart. Helvetius, Sur Pinegalitc de 

 capacite qui se trouve entre les organs destines a 

 la circulation du sang dans le corns de 1'homme, 

 &c. Mem. de 1'Acad. de Paris, 1718. Weiss, De 

 dextro cordis ventriculo post mortem ampliore, 

 Altdorf, 1745. Avrivillius, De cavit. cordis iuaequali 

 amplitudine, &c. Holler, Disp. Anat. Scl. vol. 

 viii. pars ii. p. 257. 1751. Subatier, Mem. de 

 1'Acad. de Paris, 1774. 



Treatises exclusively on the nerves of the heart, 

 Neubaiter (J. E.), Descriptio nervorum cardiaca- 

 rum, Frankfort et Leipsick, 1772. Andersch. De- 

 script, nerv. cord, in torn. ii. Ludwig Script. 

 Neural. 1792. Behrends (Jo. B. O.), Dissertatio 

 qua dcmonstratur cor nervis carere, Mayence, 

 1792 ; reprinted in torn. iii. Ludwig Script. Neu- 

 rol. torn. iii. 1793. Zerenner, An cor nervis careat 

 iisque caicrc possit 7 Erford, 1794 ; reprinted in 



