616 HKA11T. 



tilt! dull sound In the contraction of the left 

 ventricle, .mil tlir clear sound to llir contraction 

 of thr nulit ventricle. Dr. David \Villiiiins, 

 \\lnlr lie believes tliat the first sound depends 

 upon llir rush of liluod into llir l.nv.r .irlrnrs 



during the systole ol the \cninclcs, attributes 



till' srrinid siiiind to the ninsculi |i;i|iill:ires, 

 which he considers 1 as Ionium; part ol the val 

 Vlllar appaialus, causing the v:il\es In strike 



.1 the walls of the veutricles. These mus 

 ruli papill.ncs do nol, in Ins opinion, ei nlract 

 dimnr, the systole of the ventricles, Iml imme- 

 diately alici wauls, lor the purpose of throwing 

 open llie aiineiiln ventricular valves. In ;i 

 I. Miner part of this article several eircuni- 

 slanees are slaled ad* else In llns opinion. 



\\eshall now proeeed lo the explanation of 

 the cause of lliese sounds i;ivcn li\ those \\lio 

 maintain llie views of ihe rhythm of tin- heart 

 which we have here adopted, as resting upon 

 the concurrent testimony of mimerons accurate 

 observers. These may be divided into those 

 who allnlinle liolh sounds IK CUIIHS intrinsic IK 

 tin orpin, 01, in other words, to circumstances 

 occnrrmi; within the oivan ils,-lf. and into those 

 who place them external tit the Kr^iin, and 

 depending IIIKIII extraneous objects. The only 

 supporters ol the latter opinion arc Ma-.-ciidie 

 and his lolloweis Ma , n.lie maintains dial 

 "in contract mi;, and for causes IOIIL; since knoun, 

 the ventricles throw the apex of the hcail 

 a--anis| the left latcial pail of the tlioiax, and 

 thus produce the first sound, i. c , ihe dull 

 sound. In dilating, m a c,ival measure under 

 the inllnence of llie rapid mllnx of the blood. 

 the heart i:ivcs a slunk to the anterior panes 

 on the riejil of the thorax, and thus pioduccs 

 the sci on, 1 sound, the clear .sound." In proof 

 ol this, he stales that on removing the sternum 

 of n swan (an annual scl. clcd expressly Tor 

 the experiment, as it mlcrfcicd less with the 

 n.ilin.il action of the hc.nl than in the Mam- 

 maha\ he found that ihe movements of llie 

 lic.nl produced no sound, while, on replacing 

 the sternum, and allowing the licail lo impinge 

 upon its posterior surface as in the natural 

 stale, both sounds were anain dislniellv heard, 

 lie addllies several ai >.;nmellls draw n iroin tile 

 action of the luail Imtli in Us healthy and dis- 

 eased stale m lavonr of his opinion ; and he 



onsly atleinpis lo ",et ml of the objection 

 which inusl instantly sni;i;esl itself, ijiat in 



, ,IM-S, such as lrci|ucnllv occur in Inper- 

 liophy of the oiv;. m, the londness ol ihe sounds 



is di iisluil. while ihe force ol the impulse 



is increased. li\ argil mi- that in these cases ilu s 

 increased impulse depends rather upon a 

 he.mli". of the chc-l produced liv the heart, 

 which from Us meieascd s 1/r is hronuht close 

 to Us inner smt'acc. than upon a distinct im- 



{'iiiui mi nl upon n, such as lakes place in the 

 icalihy stair. Mr. Hop.', M. Itonillaiid, Dr. I'. 

 .1. 11. \\ dlianis, and the Dnlilin and London 

 llc.nl Coinmilecs h.nc, however, dislniellv 

 heard Uoih sounds of the he. in, alter thai por- 

 tion of the chest against winch il impinges had 

 lieen icniov, ,1. It ma\ . m \cvtheless, her: 

 I" ih. e expcinui nts, thai as |hc s|,.|hosi ope was 

 n.cd m many ol UK in. the impulse of tile luail 



against the extremity may have produced an 

 cllect similar to its impulse against the pai iclcs 

 of Ihe thoiax. M. llomlland, haxni- appa- 

 rently this objection in view, slates that the 

 rubbing of llie heart diirmi; its mou mints 

 against the exlrcmilv ol' the ttathotOOpe, is 

 easily dislmi;uisheil fioin llie sounds of the 

 hc.ni . and lhal lie has di.lmelly heard both 

 sonnils, thoni;h feebler than lhroni;li a stetho- 

 scope, as was to be expected win n not him; bill 

 a cloth was nilcrposed between his naked ear 

 and Ihe surface of the heart. Dr. ('. .1. H. 

 Williams, in hisexpeiinicnls, heard bolh sounds 

 when the stethoscope was placed over tin 

 of the laiv.e arteries, and where no exlein.il 

 impulse could lake place : and this observation 

 was repeated by the Dublin Committee. The 

 Dublin Committee heard bolh sounds thiou-h 

 the stethoscope, llioii';h feebler after the peri- 

 cardium had been injected wilh tepid water ; 

 and in another experiment they were also 

 heard when llie car was simply approximated 

 lo the origin. From all these experiments, I 

 think iheie can be little doubt that the move 

 mcnls of the heart, independent of all extra- 

 neons circumstances, are attended by a double 

 sound. As the impulse of the hear! against 

 the chest must produce some sound, as any 

 one mny convince himself by making ihe ex- 

 periment m the dead body, and as this occurs 

 dm ni". the systole of the heart, or, in other 

 wonls, diirinl; the fust sound, it may increase 

 the intensity of that sound. Dr. K. Spillal, 1 ' 

 alter rclaini:; several expeiimcnts in which a 

 sound similar to that of the first sound of the 

 heart was heard by tapping jjently with the 

 apex of the heart or the point of llie lni".ei 

 against the chest, both when empty and when 

 filled with water, and after point in;; out several 

 some, sol' fall. n \ which he supposes w en not 

 Millieiently unaided as'.auist in the experiments 

 which we have adduced above as subversive of 

 this MCW, and which dcscive the attention of 

 future experimenters, comes to the conclusion 

 that " it is highly probable that the percussion 

 of the heart a",ainsi the thoracic pancles during 

 the contraction of the ventricles assists male- 

 rally in the production of the first sound." 

 lie is also inclined lo believe "that the act of 

 the sep.uatioii of the heart from the thorax after 

 its approach, which was found m Ins experiment 

 to produce a sharp, short sound, somewhat 

 rescinhlmi; the ordinary sound, max in certain 

 circumstances be an assistant cause lo the 

 second sound. "| Mni;eiidic's explanation of 

 the second sound is completely untenable. 



. \moni; thosewho maintain that these sounds 

 depend upon causes intrinsic to the heart, tin 1 

 first annul is referred by Kouanct, lidhiur, 

 lirv.in. and lioudlaud lo the rapid approxima- 

 tion of the auiiculo-vcntncnlar valves dinni-.', 

 the systole of ihe ventricles, to which Itouillaud 



" dim. Moil. ;inil Surir. Ji>nrn:il. Julv ' ii;ili - 



t 'rtuiil:.)i Or. S|ntl.il is uu Inu-tt tol>rli<-v,- lli.vt 



lllC illl|Mlls,' |tf III!' II, ,11 .1. ,,ln>l til,- , Ilfst lllsl">\ 

 Sltll-l.ll'l,- sIl.UI- III ll,.- pi. '.In, II, -M ,,1 (111- UlNl s, ,1111,1. 



In- ,1,,,-s noi i,,ii,m wiih M.tniulu- m Uu- i.-\\>l.mu- 



II, Ml "I till- .-I, VMl,l .-iMlllll. 



