in: ART. 



017 



adds the Mulilin separation of tl' scmdnnar 



VahrS wlldl the blood !> foil 111 Illlll tin- I. II I 



arteries ; by Mi . t '.u lisle In ilir in -In in 1 , ol' I lir 

 lilnnil aloui; the iiuirr surface of tin 1 large 

 arteries during the systole ot the \enuieles, * 

 Dr. Hup', in tin 1 .I|I|M-III|I\ to the second 

 rililion cil his \\iu-k, describes il as consisting, 

 1st, |IOSM|I|V o|' .1 di nn i- of valvular ,-ouml ; 



I'll, ol a loud -111.11! Miiinil pioduced li\ (ho 

 abstract act ol a sudden jeiknr'. extension ol' 

 Ilir innsciilar walls, in the same UI.IIIIIIT that 



such a s nl is produced by similar cxti nsion 



ol Ilir leather of a pair of bellows; to avoid 



oircumlocution, he calls u tin si>n>i<l >>/' nini- 

 sii'ii .- :iil, a pilon":iiioii and possibly an iitig- 



i.itnni of tins Miund liv tin 1 sonorous dlua- 



tkmi pri-nliar to muscular fibre." Dr. ('..I. I!. 

 \\ ill i.i ins has very justly objected tO the CORWl 

 ness of llie second cause lieie adduced as 



anlni" 111 il e productioQ of the first sound, ns 

 ilir phrase " sound of cxti nsmn" is olivmuslv 

 contr.nlictiii'y when applied to a conli.icln.i; 

 I Dr. ('. .!. It. \\illiams maintains 

 " lli. it llie first .sound is piodiiccd hy the mus- 

 cular con 1 1 act 1 1 m ilsclf," the clearness of Inch 

 is mi leased hy the i|iianlity of blood in the 

 In. HI allordin,' an oli|ect anumd which the. 

 ldue cilei inally h",liieii, whilst ihe auricular 

 Valve, liy pre\cnlini; llie icllux of the hlood, 

 ' s Us resistance, and llms adds to the 

 tension lor Ms expulsion." He was 



first led to the adoption of this opinion by the 

 oliservahon.s of I'.ninan and Wollaston upon 

 ihe existi nee of a sound accompanying every 

 rapid muscular contraction. This opinion he 

 afterwards put to the test of experiment, the 

 results of winch we ejvc in Ins own words. 

 " l''.\pi iinieiit Isl, olisen.ition i'.th; I pushed 

 niy linger through the mitral orifice into ihe 



lell \cnliii le and plessed on llie right SO as to 



prevent llie influx of hlood into cither ventricle ; 



the 11 utricles continued in conlnict strongly 



i'ly \\lien irritated liy the nail of the 



"ii the left), and the first sound was still 

 distinct, bill not so clear as when the ventricles 

 contr.icied on their blood. Observation '.Mh. 

 The same phenomena ueie observed when hoih 

 tin arteries were -i\,ie,l h..m the heart." lie 

 also found in other observations that the first 

 si. mill was leudcl o\el ihe suil'ace of the vcn- 



ihan over (he 01 1 m ofthe 1 

 which is in direct OftpodttOtl to the o| on of 



(hose who lii'heve that this I-. pio.lneed h\ the 



rush of hlood aloii" ihe net* nt, in. '['hal 

 the lust sound is not dependent upon the closing 

 of the auin n!o U'lilni nlai vahcs. In 



iicd Ii I'll .1 M.IIIOI: ., in which the 



closure of these valves was p.ulially or com- 

 |>lelely prevented, and yet the first sound was 



*"ill heard. Itcsnli i, tin, mind Inmes 



ihe whole of the ventricular systole, 



while the shnlllll'.; of llie \al\es must lake pi. ire 

 and lie cnnipleicd at the commencement of llie 

 M stole." That thecolli-ion of the particles of 



* As Mr. ('.irholi' is ,i mi'liiluT of lln> Diililin 



"'"I Committu, ' niii-a ii, -M riiusniiT I us 



concurring with UM rrpoH "i ill ,i Cii 



t Jli.iii.il i..i., u, . s, pi. 



thud in the ventricles i oes not produce this 

 sound he was conduced fioni ohsii\.ili 

 which il eiinliniii d allhntigh there was no blood 

 in tin M nil 



'I'liounh we must admit dial ihcse expeii- 

 inenls of Dr \\illiams pio\e dial part at le.isi 

 of ihe fust sound is cause I hy die muscular 

 conli.iclion of the \eiiliich s, yet We must con- 

 sider it still problematical, until we ohiam 



further ohsinai s, whether it produces the 



whole of thai sound, for it is very possdilc that 

 some of the other ciicnmstanccs attending llie 

 systole of the heart may increase its intensity 

 M M.ne d'1'.spine has maintained that holh 

 sounds depend on muscular movements; the 

 first sound upon the systole, and the second 

 upon thr diastole of tl.e ventricles. The Dub- 

 lin ( 'ommitlee have m the meantime i , included 

 that the first sound is piodnced cither by the 

 rapid passage ofthe Mood OM i il,. M, nlu 

 internal sin lace of the ventnclcs on its way 

 towards the mouths of tin aiicncs, or l>y the 

 bruit mutciiliiirc of the ventricles, or probably 

 liy both these causes. We must wait for fmihci 

 cx|)eriineiits before this question can IK l.mly 

 settled.* 



Second tound. Later experimenters appear 

 to be more nearly agreed about the cause of 

 the second sound than that of the first sound. 

 M. Itouancl appears lo have lu-i u the first who 

 publicly maim. oned the opinion that the second 

 sound was de|>endent upon the shock ol blooil 

 agtiinsl the semilunar valves at the origin of 

 the aoita and pulmonary artery. M. Itniiane.t 

 himself acknowledges that he owed the sug- 

 gestion to Dr. ( arswell, at that time studying 

 in Paris, who came to thnt conclusion by a 

 beautiful process of reasoning upon the plum, 

 menu which picsenled ihemselvcs in a cose of 

 aneurism of the aorta. The same opinion has 

 heen supported by Hilling, llryiui, Carlisle, and 

 Itoiiillaud.t It ls > however, to Dr. ('..I. II. 



* The Ixmilon Commiltoo, in their report givon 

 in t Ihe meeting of tho llriliih .Scientific Auocia- 



I l"r KUii, hive inliliiri-il mine additional expo- 



rlmcnm in favour of iln- n|iiiiiuii ihut iliu Ant 

 ound of the heart drpcniU upon inuicular con- 

 traction. It appeared to them that thr s, ,,,,,, | |,,,, 

 iliu nl hy the contraction of tho abdominal mu>clci 

 ns heard through a flcxihlo tube re*rmhloi tho 

 s\si,,lii i, MUM I. They, however, admit thai though 

 " ihe un|iiilsi. ii not tin' IIMIH iji.il cauie of the Aral 

 . "mill, it in an auxiliary and occn<iimnl 

 nearly null in i|nirtude and in the lupine p,,Mui, . 

 Inn mi icuning very conxidrmhly the >und of the 

 nysl"lr ill o|,j,"Mli' I'irrunistiiiH *." [''nun I In- i-n.it 



care with which theto experiuirnti appear lo have 



brrii |irifnrmril, we lirlu-vi- that wo iiH 1 now fully 



ilns rx|,l.ii..,n,.ii "i il,,' cauio 



nl ll" liim Hound. The Dublin Coiiiiuill, r . in ilii-ir 

 ri'i'ou i m u ill nl the dame time, nlv> dolnil tiunn 

 e\|irrinn'lin wlmh lhi-\ hrlicve til hr ( onlirnilltory 



of ih, u ti.i ,,,. , . i,.i, lusi.mv Sir Sixth Itrport of 

 llnli^li Si ii'iililii As,n i , 



t In pish, r l,> Dr. Mlliotl, of t'iirhsl, , I must 

 si. Hi- th.it I lind, ,'" , "iisiillinj; fun Tin 

 Corili- Ifiiinano, |>ulil islirit in l''.ititiliurt;h in iH.'tl, 

 lh.lt hr Nlnlm (p. ,'! ) lh.il In- lu-llrvi-s l! 

 srrolul siiiillil ,'t llirlir.ol 1 s ,1 , |i, 111 1 , lit HJMIII t| M . 

 rush of 111", nl Iroin tl,r .1,1,1, 1. . ml,i tin- vrulruli's 

 during thi'ir i!i.isl,,li'. ,01, 1 .,1.,, ii| il,, ,,,!.l, n 



H.ippinK niw.o'ii i,i ilu ilgmoid valvei .nil,, 

 of the l.'i ' on in ', by tin ii llui'ut bluod. 



