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M. FIOSTER, M.A., M.D., LL.D., F.R.S., 

rtt'-FnritjK ov i-hysiotouy in toe i'mvkfwtv ok CAiiEHinGE, and rEUX>w «f trinity 








Ih the preaent ediUoo I have made oonridenble chuiges and addition! ; 
bat in the changes I have tried to nudntain the cbaiw^er of the book as 
{weaented in in«yioiu edition! ; and the additions, with the ezoefAion of 
tbe histological paragraphs, are oaosed not by any attempt to add new 
matter or to enlarge the goural soc^ of the work, but by an efibrt to 
•zplain more fdWj and at greater length what seem to me to be the most 
fbndamental and most important topics. I hare beoi led to introdnce 
some bistolopcal stiUements, not with uie view of in any way relieving 
tbe stndent from tbe neoeaity nf sbidying distinct histolc^ical treatises, 
bat in Older to bring him to the phyuologjcal problem with the histological 
data fresh in bis mind. I have therefim dealt very briefly with the 
several histological points and confined myself to matters having a physio- - 
logical bearing. Hy friends. Dr. Gaskell, Mr. Langley, and Dr. Lea, have 
given me great assistance throughout, and their names might fitly appear 
on the title-page, were it not that the present arrangement makes me alone 
responsible for all shortcomings. I have also to thank my senior demon- 
strator, Mr. L. E. Shore, M.B., and my junior demonstrator, Mr. Wing- 
field, M.A., for much valuable aid. The second and third parts will follow 
this first part as soon as possible. . 


I AM of course aware of the disad vantages of issuing this edition of my 
Text-boot in instalments, and very much regret that this part does not 
complete the work. The failure to get the whole of the remainder ready 
has been due to lack, not of will, but of ability and opportunity. 

I take this opportunity of thanking my friend. Dr. Gowers, for the loan 
of two woodcuts, as well as for much valuable advice. Throughout the 
whole of this part I have been largely assisted by my colleague, Mr. 
Langley, and by my friend aud former pupil. Dr. Sherrington. The 
latter, besides helping me with criticisms, has prepared for me most of the 
figures after original drawings by himself What little merit there may 
be in this part is largely due to these two gentlemen. 


CiMBKiDcm, September, ISflO. 


Thb Mtthor's pn&oeB to the eeveral parte, in which this edition was 
imied in fiogland, will show how thorough has l>eeQ the revision to which 
H hw beeo Bafajected. Tlie task of the Amerioan editor has, therefore, 
bean mostly coofined to the adaptation of the work to the wonts of the 
Asmioaa stad^t, Among the principal additions will be found refer- 
eooee to the phyriolo^cal action of some of the more important drags, 
and the test has been elucidated bj an increased number of illustra- 
tioais. All matter thns introdaoed has been distinguished hy inolosure in 
bnckets [— ]. 

Pb 1 1.1 DELPHI A, October. ISSI. 







The Clotting of Blood -ii 

The ( "onmscles of the Blood : The Red Corpuscles -H 

The W'liile or (itolorless CorjmscleB Ill 

Hl.xxi PlateletH 68 

Tin- ' 'heniicul Compoeiiion of Blo<id KO 

Tlie ijiiiinlit^ of Blood, and itn Distribution in the Body . . . . Tl 


The Phenomena of Miiwcle and Nerve : Muscular and Nervous Irritability 73 

The I'henometia of u Simple Miiacuiur Ponlrflftion f^'i 

Tetanii; l.'ontrHctiona 'J1 

* In the Chanpw which Take I'hicv in a Muscle Dnringii ('mitriiction: The 

t 'han^e in Form ........... 94 

The i 'heraiatrv of Muscle 1U4 

Thermal Changes Ill 

Klt-ctrical Chaiijres 113 

The ("hanger in ii Nerve during the I'lumiige of a Nerviin^ Jjnjiulsc .UN 

The Nature of (he Changes through which an Electric i urrciil is Able to 

(ienerate a Nervoun Imiiulw: Action of the Conwlant Current .!:;■< 

The Muaele-nerve Preparation aa a Miichiiie I3,i 


The Circu instances which DeCermiDe the Degree of Irritability of Muscles 

and Nerves 140 

The Energy of Muscle and Nerve, and the Nature of Muscular and Nervous 

Action I4<) 

On Some Other FormH oC Contractile TiMue: Plain, Smooth or Unstriated 

Muscular Tissue 149 

Ciliary Movement ..... 154 

Amceboid Moveinenta 157 



The Structure and Main Featuresof the Vascular Apparatus , 17.'! 

The Structure of Arteries, Capillaries, and Veins 173 

The Main Features of the Apparatus 18!i 

The Main Facts of the Circulation 184 

Hydraulic Principles of the Circulation 193 

Circumstances Determining the Rate of the Flow 199 

The Heart a06 

The Phenomena of the Normal Beat 20<i 

Endocardiac Prmsure 213 

Summar; :]24 

The Work Done 22."> 

The Pulse 22G 

The Regulation and .Adaptation of the Vascular Mechanism : The Regula- 
tion of the Beat of the Heart 240 

The Histology of the Heart 241 

The Development of the Normal Beat 24-"i 

The Government of Heart-beat by the Nervous System .... 2.';J 

Other luliuenceg Regulating or Modifying the Beat of the Heart . . 2<>:! 

Changes in the Calibre of the Minute Arteriex. Vasomotor Actions . . 26-~> 

The tkiursc of Vaao- constrictor and Vasodilator Fibres .... 27:! 

The Effects of Vanomolor Actions 27.') 

Vasomotor Functions of the Central Nervous System ..... 27i! 

The Capillary Circiiluti'in 2.S(> 

Changes in the t^uiintiiy of Blood 291 

A Ueview of Some of the Features of the Circulation .... 292 






The Oharactera and Properties of Salira aad Gastric Juice: Saliva . . 302 

< raatric Juice 307 

The tilriicture of tlie Salivary Gland«, ihe Gastric JIueoua Membrane, the 

I'kDcreas, and the CEsophagus ''IT 

The Siructure of the Stomach 319 

The .'■alivary Glands ^^^ 

The I'aDcTeaa 328 

The Structure of Ihe (£«o]>h&gus 330 

The Act of Secretion of Saliva aod Gastric Juice and the Nervous Meelian- 

i^mt which Hegulate it 332 

The Changes in a Gland Constituting the Act of Secretion , , . 339 
The rroperties anil OharacteM of Bile, Pancreatic Juice and Succus 

KntericUH 351 

Itile :«! 

I'auiTe.itii; Juice 3.54 

."■iiccus Kntericus ,...,.-...■■ 358 

Tlie Secreiiim of Pancreatic Juice and of Bile ...... 3o9 

The Structure of the Intestines: The Small Inleatine .... 365 

Tiie Lar^ce Intestine 3i4 

The Muwular Mcchanisni!> of Di^jestioii 375 

Tb.' Changes which the Food I'ndergoet in the .Vlinientary Canal . 3W 

The (.'hnnges in the Stomavh ■*'*■' 

In the Small InteHtine ■'«! 

Ill the Large Intestine .......-■■ 39;) 

Till- Fei-ew 3!''> 

The Lacteal)! and the Lymphatic Syntt-ni 31Nj 

The Lyriipliatic Veiwels '■'•*' 

Lymph ciipil la rie.* '■'■'•'' 

TI»'.'=trnctureof Lympliaiictilunds -1"- 

The Nature and MovenieiitM of Lymph (Irirhidirig Chyle) . - -1'"* 

The Chnratters of Lymph ^"'■^ 

Tlip Movemt-nta of Lympli ^ll 

.\li-iirptiiin from the .Uimeiil:Lry Canal 419 

Tin- CoumeTalien l>y the Several I'roiluct.-* of Hige-tLiiu .... IIH 

The Slechani^ni of Ahsiirptiori -I-'* 




The Structure of the Lungs and Broucbiul PMssagen 4:11 

The Mechanics of PulmoQiiry Res gii ration 43K 

The Respiratory Movements -i*-* 

Changes of the Air in Respiration 44!> 

The Respiratory Changes in the BiooU *)I 

The Relations of 0:cygen in the Blood 4-35 

Products of the Decomposition of Haemoglobin 4I>3 

The Relations of the Carbonic Acid in the Blood 4)iii 

The Relations ot the Nitrogen in the Bloi>d 4ti7 

The Resjjiratory Changes in the Lungs : The Entrance of Oiygen . . 4Gr 

ThcEititof Carbonic Acid 470 

The Respiratory Changes in the Tissues 471 

The Nervous Mecbaniam of Respiration 475 

The Effects of Changes in the Composition and Pressure of the Air 

Breathed 402 

The Relations of the Respiratory System to the Vascular and Olher 

Systems . .' 496 

Modified Respiratory Jfovements ■"•"O 


The Structure of the Kidney . ■'ill 

The Composition and Characters of Urine '>24 

AmountH of the Several Urinary Constituents Passed in Twenty-four 

hours. (After Parkes.) -J2S 

The .Secretion of Urine '>29 

Secretion of the Renal Epithelium 't^i' 

The Discharge of Urine ■'>46 

Micturition '>48 

The Structure of the Skin V)] 

The Nature and Amount of Perspiration ....... 'iW 

Cutaneous Respiration .IliO 

The Mechanism of the Secretion of Sweat .'•112 



The Structure of the Liver .'•(i-'i 

The History of tilyc'ipeu 'iT'.i 

Diabetes ■'•^'- 



The S{ile«n TiSS 

The FDrmation of the Conatitueats of Bile 595 

On Urea and on Nitrogenous Metabolisin in Ueneral 599 

On i*onie Structures and FroceeneH of Obscure Nature .... 607 

The History of Fat. Adipose Tissue 614 

The Mkmmary Uland 620 

Avt-rage Com poei lion of Milli in Diflerent AnimnU 624 


The fftatlstics of Nutrition 628 

(.'o[n]iiiriBon of Income and Output of Material 630 

The Enerpy uf tlie llody: Tbe Income of Energy 637 

The Expenditure 638 

Animal Heat 641 

On Nutrition iu General 662 

«>n Diet 660 





( *u Slime Features of the Spinal Neries 671 

The ."Structure iif the ."Spinal ( Vird 676 

The Reflei Actions of the I^piiial Cord 711 

The -Autumatic .Vctions of the Spinal C'ird 724 

CIlAI'TKH 11. 


t >ri S(.me General Featurex of tliv Slnutiirr of the Brain .... 731 

The itulh 7;!(i 

The lJis|>osition and Oonneciiipii- <>!' tin' Oriiv and White .Mutter <>( the 

Ilrain: Theliray llatler T4'< 


The Central Gray Matter and the Nuclei of the Cranial Nerves . 748 

The Superficial Grny Matter 762 

The Intermediate Gray Mailer of the Crural System 762 

Other Collections of Gray Matter 772 

The Arrangement of the Fibres of the Brain 774 

Longitudinal Fibres of the Pedal Sytitem 775 

Longitudinal Fibres of the Tegmental System 778 

Tranarerse or so-called Commissural Fibres 781 

Summary 782 

On the Phenomena Exhibited by an Animal Deprived of its Cerebral 

Hemispheres T>^4 

The Machinery of Coordinated Movements 790 

On Some Histological Features of the Brain 79^ 

The Superficial Gray Matter of the Cerebellum 800 

The Cerebral Cortex 803 

On Voluntary Movements 808 

On the Development within the Central Nervous System of Visual and of 

some Other Sensations : Visual Sensations 83ti 

Sensations of Smell 847 

Sensations of Taste 8o() 

Sensations of Hearing S-'iO 

On the Development of Cutaneous and some Other Sensations . S'>I 

Some Other Aspects of the Functions of the Brain K6''i 

On the Time taken up by Cerebral Operations 873 

The Lymphatic Arrangements of the Brain and Spinal Cord . 676 

The Vascular Arrangeinenls of the Brain and Spinal Cord .... 881 



Pbysiolc^ical Anatomy of the Eye 887 

Dioptric Mechanisms: The Formation of the Image 894 

Accommodation S'J^'i 

Imperfections in the Dioptric Apparatua 90.'> 

Visual Sensations 908 

The Origin of Visual Impulses 909 

Simple SenaatioDs 'Jl."> 

Color Sensations 918 

Visual Perceptionii 9L'-% 

Modified Perceptions 927 

Binofuiar Vision : Corresponding or Identical Points 9;it) 

Movements of the Eyeballs 9:W 

The Horopter 9:i4 

Visual Judgments 934 

The Protected Mechiinisma of the Eve 9:!7 




lleurin);; I'hjsiott^icHl Anatomy of the Enr 939 

The AcnuHtti' ApparalU" ... .... 946 

Au<]itory ^nxAtiniis .... , ... 94S 

Auditury ,Iuclginetit« !iri2 

SiufU: rb.vsiulogicsl Anatomy of (be Nasal Fusiia! 9.'>3 

Tafte : I'hjBiologicai Anatomy of the Gustatory Mucous Membran*^ . !>M 

C'lIAPTEIt \. 


■ ieneriil Sensibility and Tactile Perceptions 960 

Tnctilf Sensations : SeasHtions of Prew'Ure Dtil 

.-^f niuitii)nB of Temperature 9(>2 

Tactile PerceptionH and Judgmcnr^ 9t!4 

The Muscular Sense 966 


TheVoiie; The Pliysiologlca) Anatamy of llii- Larynx . . fHiS 

Sjieech ; Vowelii ..... 974 

l.Vmmtnaiils .... 97^1 

I.oconiiitur Mf('hu^il^mB . 977 


THE Tlss^■^:.<5 ,\si> mechasisms or HEritcun'mox. 

(.11 APTKi; I. 
UlUiANS (H- KEl'imiin TKIN. 
Tlie I'hT!'ii)logiciil .\ii»tiifny of ilie "rpirm 'irdeniTutioii . 9S2 

CllA I'TKi; 1 I. 

MENsrillATHiN . . us? 










DEATH . 1013 

A P P K X D I X . 





|L Dnurriox, aM«l l)f tuIcroMoptcal examination, IcitobM us ihat 
Iba bodr of uuui is vamt\« un >i( c*^riain kiiiiltt uf uauHftl, «» ilifli^ring Anm 
Mch niMf In uptical iio'l oilier |ili)'*ir'itl oliuractora ami *o built up logCtlMtr 
a» lo gift ibt body cvrbiin olructural fmturM. Clii-iiiiunI I'xaininntioD 
flutbtr UMba IM UuU iIkw IciiKlo i>f nuit'-rinl nn- r4iiii)Hi«n) of various 
dMBlical aubOAnOM,* largr niiriitwr tif iihicli liitvi? lliiM vliitnuumti'' thnt 
Ibftjr |M«MB • CDtuidArable luiiutiDl ol' pvlvutial vficrgy <:iii>iiblo of Imidk mI 
frw. fmiUTtd actual, by oxi'Iittion or Kitno other dM-micnl cluingc. Thus 
ibr bndj, u a whuk-. may. fmm a cbemtciil point of viow, Ira ct)usidorod as 
■ u*m of various cht^micml substADflM, rpprawnling altogether a oonsidora- 
bU capital of {Mtential energy. 

iS. Tbb Inxly rnny exisl fith<-r tis a living body or (for n certain time 
■1 tSBSl) as a dead body, and the living l>ody may at any time booome a 
dMd body. At what is geoerallv calle<l the moment of death (Itut arlifi- 
eUly to, for as we aliafl see t^e processes of death are numeroiia and 
gnHMnl) tbe dead body so fkr as structure and chemicnl romiMiaition an 
CBdOCrasd >• esceedbgly like the living biMly ; indevl the dittVri-im;* b«- 
tWMn iba two are Hicb us can Iw deuruiined unly by vi-Ty carofnl i'i«niiaa- 
tiao. six) are ritll tit a largi' I'xlcnt estimated by drawing infrivncoi rnlhor 
actually <>Wrveil. At any rate the dead l»Hly at llii> luonieiit of death 
ibla thi- living body id hu fur an it rcpnveoUa GUfNtal of potential 
Pront tliat mofncot ouwsnl. hnwovrr, the cnptMl is expended ; by 
vbich nn- Inrp'ly i!u.w of oxidiiiirin, ihc ttoi.-rKy i" gnidoslly dis- 
aipBlad, leaviDg the Iwdy chii-tly i» tlie form of heal. While thc»e ohomical 
[wwcBMM atw going on Uio structural features disappsar, and the btxty, witb 
tbm ln« nf nearly all ittfenergr, if «i hut rasolv«d into "dust and aahoe." 

Tfao tiharacterislic of the dead bixly then is that. Iwing n maw of sub- 
■laaciv of coDiidcrable polcnlial eaergr, it always more or tern elowly 
{■lag seergT, never gaining energy ; ibe capital of energy preecnt nt the 
■ooMit of oMtb is more or less slowly diminishod, m never increased or 

|3. When on tli« ntfaer band we study a living body wo ar« struck witb 
ibc fullowinj^ Ntlicnl fads : 

1. Tbe living body moves of iUelf. cither moving one part of the body 
on a04itber or raoviug tbe whole body frtm [iloce lo place. These utov*- 

arc active; llie biidy in not (iiniply pulled or pushed by external 
lann, but i1m> motive powfr id in the body itself, tbe energy of each more- 
nsttl i* supplieil by tbe budr it»elf. 

2. TbflK niovtrnuiits uo OetnrmitKil and inSnenocd, indeed often sewn to 
slan4<l, by duugM in the surronndintpi of the body. iSuddeu contact 

the sur&oo of tb* b"dv and wme foreign oliject will often call 



fortli n nifivcciipiit. Tb« body is wosilive to chonxen iu iu surroun< _ . 
arKl tlii; fcnniLivi-iK-H u iDaDifceud uoi only by niovenictila tmi by OtStt 
choDgcs in thn boctr. 

3. Il is contintiiillr gtroerftting heat and giving out bent losurrouiidiii); 
things, the produdioii nixl Ium of ht-nl, m lh« vnbw ol' nimi uod ci^rtniit 
oilier aDimslR, being to ii<iju>l<(l Omt lliv uliulti burly i« wurm, tliul t* of ■ 
l€iui«rtiiurc Iiiglior thiiti tliut ot KUrroiiodiiig ihitigit. 

4. From lime to time It cnU, thm is to «ty tnlc<:i into itself supplies of 
ccrtnio eubnlntices known m fooil, ihvm sutMlmici-s boiiig in lliv moin rirailnr 
to that which compoee Iho buity, itni] bi-ing ]ik<- ihcm dicmicfll bodiiv of 
OODBldeniblfi potential energy, cnpnblc tbrougli oxiiljilion or other chemiciil 
cbangee of setting free n considcntble (luunlily of energy. 

5. h is continually brenllilng, that is, Inking in from the surrounding air 
supplies of osygcu. 

6. It is continually, or from time to lime, discharging from itself into ile 
turroundings eo-called waste matters, which waete matters mny be broadly 
described as products of oxidation of the substances taken in as food, or of 
ihv tiubstances c'omjKiBing the body. 

Heuce the liviuj; body maybeaaid to hedistin^ished from the dead body 
by liircb main features. 

The living hoily like the dead is continually losing energy (and lonng it 
more rapidly than ibe dead body, the si>ecial breathing arrangements jier- 
nitting a m«re rapid oxidation of its sulistanee), but unlike the dead Ixxly 
is by loeana of fond continually restoring its substance and replenishing its 
store of energy. 

The energy set free in the dead body by the oxidation and other chemical 
changes of its tiibslance leaves tlie body almost exclusively in tbe form of 
beat, nberens ci great deal of energy leave* (ho living body as mechanical 
work, the result of various movements of the body, and as ne shall see a 
gre«t deal of the energy which ultimately leaves tlie t>o<ly ns heiit, exists for 
a while iriibin tbe living body in other ibrms than heal, though eventually 
trsnnformed into heat. 

The cbaogea in the surrounding aflect the body at a slow rale and in a 
general way only, simply letKomg or increasing the amount or rate of 
cheivical change and the quantity of beat thereby fct free, but never 
diverting the energy into fuaie olher form such ns that of movement; 
vhereai changes in tbe surroundings may in the case of the living body 
npidlv, profoundly, and in special wava affect not only the amount but also 
tbe kind of ener^ set free. The dead body leH to itself slowly fiUls lo 

Eiccra. slowly dissipates its store of energy, and slowlv give« out beat; a 
igber or lower leniperuturc, more or len moisture, a free or scanty supply 
of oxygen, the advenl of many or few putrefkctive organitunH, tb't«e may 
auicken or xlack^n the rate ut ublcb energy is being tli.-elpaied but do not 
diveH that energy from heat into motion ; whereas in the living l>udy so 
slight a change of surroundingn oa the mere touch by n bair of some par- 
turn lu* turfacVi may so aflect the setting fixe of energy as to lead to such a 
disdMlf^ of mergv in tbe furm of movemi^nt that the previously appar- 
ently quiescent bcHly may be suddenly thrown into tbe mo»t violent oouvul- 

The difference, therdbre. between living snljslantT and dead sulislnnce 
though recondite arc very great, and the ultimate object of pbysiulogy 
b to ascertain how it is that living substiincc c«n do what dnid sub- 
stance cannot, can renew its substanoe, and leiilcnish the energy which it is 
cvnliuually loeing, and can, according to the nature of its surroundings, 
vary not only tbe amount but also the kind of energy which it sets free. 




Thw ihtrr oiT two gmt (livtuon* of ph^Klalggv : uoc having to ilo nitli the 
nBM««l of MbMaoM wu) tho rojtU-tnuhinvnt or oicrgy. tbo Uher having to 
de with th« Mttiiig Art of «Dorg}-. 

14, Now thtr body "f nmu (or oih- oI' iIh- hi):tirr iLnininU) in n very d^ni- 
piMstvil ■trucluiv. cuii«i#tiiij; ol' ilitli-mil kiixU oC i)iali'ri«l, which nv call 
litamm, Mirh le innsculur, i»rvifii«, (iMiin^ocivo, nnd cho likv, variuuMly 
amspd in organs snrh lu hwirl. 1iii)g«. mutclpe, «kin. vtc, all built up i<i 
fern UM bud^ awoMin); l<i o-naiii nn'riiliol'igimi Iswh. But all this vum 
pUoatioo, though lulvautngt'oug and indeed nccvesary Tor ihu fulkr lifts of 
ia oeL taKUtial lo the existcnvo of life. Th« amwha (Fig. 1] is a 

(Fw I. 


a«»rtnmiMa»ii»lnilllfcWial>iniiH]u».c)— n u i l br ■■MwmiiuilmU.I 

bctoj; il ran^WM its Mibdnnce, rvpVni»h«9i il« fivro of encrf-y, and 
eaergjr now in one form, now in unolli^r; and yet tho »m(Bba may 
he <•■>] ti) hare no (ueunt and no orgnni! ; al nil cvx'nt« Ihis is true of cliiaely 
alltnl Uui not ft well known simpU' b«ings. U*int; iho more fHniiltar 
maaaln aa a lyp<^. and. lbcr«fori.>, leaving on one Fide ihc nucleua. and aor 
ifclllii linn between enduurc nud eclcKin-, wv may say that iu Imly W 
boataceaMUB in thf aeoac (hat if we divided it inio small piecea, each pleoe 
vmtlalM! lik« all the nthera. In another sense it is not bomoffeaeoua. For 
wa knn** (bat the amioba T««eivee into its sulwiaut.'e inateriu m* fuod, and 
tk*i thu frxid or part of it reruaius lodged in the body, unul it is made um 
of and liuilt up iul^t ibe living substance of the Itodj, and each niece of the 
Bvios Mibatancr «f the body mum have in or near it some of the material 
«Ud tt •• al>»ut to build up into itaelf. Further, we know (hat ihe aniwha 
^vw PUl watte mattvra mcfa a« carbttnic acid and other subttaiicea, and each 

ecc of Uio aiarrtw lauu contain Kiiite nf theae wnate maUers abotit to be. 
( not yat, iliachatgad frofo the |>iece. Each piece of ihe amoeba will, 
tbatvlhrw, mntain ibMO three Ihinga, the actual living subalanoe, the food 
at- I" living (tibatiiDCo, and the waate matter* which have eesaed 

U..rftcr, wv have renauno to think (.hnl the living »iib*tanoe doea not 
hnak down int» (hv waMo mattcm which K«ve ih*! Imdy ui a dngle bound. 
iMt ihara arc Mui.'v* in (he d'lnnwiirti pntgnw liciwe«n the one aud the 
•char, fjimiliirly. ibongh uiir knnwlivlge mi rhio (H)int in !<■** inrv, we have 
naaiiri U> Ihink that ih*? lnttA is not iDOi>rj>oral<-il into (he livingnbatanco at 
atio^ tie]!, but that there arc Xagea in llw nimard prngreai f^om the 
' food to the llvinjc aubatancc. Each piece of the body of the am<»bii 


nil], Uierofure, contain Bubstancoa npreeeiiting various etages of becomioK 
liviag, Bnd of oea^iii]; to be living, as well as the living substAiice ilself. 
And we may safely uinke ilib slateiiieiit, though we are <iuite uoable to 
draw ihc line, where the dead foixl mi iu way up becomes living, or tbe 
liring tiibnlaticc on iu way down bec<iiuee dead. 

Sft. Nor id it nece*iBary for our present [iur[i<we In be able to jioint out 
under thv inicnwrofM;, or li> itotcribe frurn ii bial(>l(i){ii.-«il )ii)inl uf view, tlie 
part^ nhirh are living' and llie purlii uhicb an^ dfad fiiod nr drad wanu. 
jIiv biHly of till- ani<i;ba in rri-<|Ui.''iiliy sjinki-n uf a* ounMtiling of " jiroto- 
plasm." Tlie name wita orifiinaH > given in the niiiUcr funning thv iirimor- 
dial utricle of ihu v^Mab)*: fell n-' ili»tiu|iii9ln'd fnim tlic d-ll walfoo the 
on« hand, aud frum thn fluid c»nt<'nl> ot Iha- oi-ll or l-cII sap on die othrr, 
and hIho wo may add t'ntm the niicli'ue. It ha» «inco been applied very 
generally to Ruch parlx of animal boiltcs as n^cimble. in their general fea- 
lure«, tlie primonlinl utricle. Thus the l><>dy of a while blood -corpuscle, or 
of a gland eell, or of n nerve cell, i* said to consist of protoplasm. 8uch 
pans of animal bodies &;< do not in their general filatures re^mlile the 
matter of tbe primordial utricle are not called protoplasm, or, if they at 
•ome earlier stage did benr such resamblance, but no lunger do so, are some-' 
tiroes, as in the case of the substance of a muscular fibre, called "diireren- 
lialed proto[ilflsm." I'roloplnsm in this sense Bometimca appeals, as in tbe 
outer part of most amceba:. as a luaaa of glaesy-lonking material, either con- 
tinuous or interrupted by mure or less spberica] suaces or vaouolen 6lled 
with Buid, sometimes as in a |;land <%ll as a more retractive, cloudy -I looking, 
or finely granular material arrau^ed in a more or lc«a irn'gnlar network, or 
spnngowork, the inier*ticeH of which are occupied cither by fluid nr by *ame 
material iliflerent IVoni itself. We »halt return, however, to the fvuturcM of 
this " prulopliwm " when we conic to treat of white blood-corpuscbis and 
olber "protoplonmic" <truclurKL Mentiwkile it is sufficient for our present 

iturpose to note tliat lodged in the protoplasm, discontinuous with it, and 
brmiog no part of it. are in the firvt place collections of fluid, of watery 
solutions of various substances, oci'Upyiog the more regular vacuoles or 
the more irregular epaoes of the network, and in tJie second place discrete 
granules of one kind or another, also forming no part of tbe protoploiiu 
iLsvlf, but lodged citbei- in the bars or substance of the protoplasm or in the 
vacuoles or meshes. 

Now, there can be little doubt that the fluids and the discrete gnmulu ara 
d*Md foixl or dead waele. but the present state of our knowleiTgir will not 
permit us to make any ver)- definite statement nboul the prot«i]ilnsui it*elf. 
We may prubably cuucludc. indeed we may be almii>l Hunr, that pnitnplnsm 
in the above sense is uot all livinjc Hubstauce, that it i* made up partly of 
the real living iiulbtnni'e, and partly of material nbieh n bovuming living or 
luis cpiUM.-d Ui lie living; aud in the caa^ wlien^ prtrtuplasm is dnoribco as 
fenniog a network, ii is iiiK'>ible that some of tbu mnicrial occuprin^' the 
mcshm of the notwnrk may W, like ^rt of the network itm^ll'. really alive. 
" Pnrtopbism" in fact, »-■• in the nwiio in which wc arc now using it, and shiill 
continue to use it, i» a nwrfihuliMjiml lerni ; but it tnust be iMime in mind that 
llio same woni "protoplasm" L* alwi Irpiiuently used to denote what we have 
just now called "the rtial living sulxrtnnre." The word llien embodies a fihy- 
niologiealidfii; so UMil it may Iw applied to the living eubittauceof all liviOK 
Btnicturre, whatever the microecopicnl features of tboec Htructures; in this 
sense it cannot at prrcont, and piwsibly never will be recognized by the micro- 
scope, and onr knowledge of its nature must be bused on iufereooea. 

Keeping then to (he phrase "living subslmiee" we may say tliat each 
piece of the body of tbe araai?ba consists of living substance, in which are 




lodnd, or wiih wim-li nrv l>uill uj) in mih^ vay or utbcr, food sod wnste in 
TmiVHu lUgte. 

Now. M) ftRioba nay divide itself into Iwo, acb half exhibiting nil the 
phrBoHMOa of lh« whole; and we caD easily imnKine the proccM lu be 
rHHU«d, until the amatba was divided idIo b niuUitudc of exceedingly 
Mtaota aintrbii-, cat-h having aJI the properties of the orij;inu). Hut it ia 
slnrioa*, *■ iu ihv like divisioii of a maea of a clieniical Hubttuiiee. that the 
ditrUoa owild ui>t he repeated indctiiiilely. Just an tu divi«ioi> uf the cbein- 
kal mtm we r<»iuc to (he cWinicul molecule, further divUion of which 
ihangw iIm pruiwrtiee of the HuhDtnnt^, *» ia Ihe ooutitiued divbiun of the 
amrrha we should runte lo a aiiae iu which further diviaioit interr«re<) with 
tl "gicnl si-li<>»d>. we iJimitd ui>iii«toAphy«ii)lc>;;ifal unit, curnwjioiid- 

iii.i ;rv«lly niun* couij>lex ihoo the chemical inoleailc.' Thid tinit lO 

nmain « iibyvioliijtical unit and to conlinne to live muitt viiniaiu um only a 
pwnluci of tltv livinj; KuliMaDou but alto the food for that liviuj^ itulMtance, 
ID MTtral at li<«)4 of tlw Mak^. frum th*3 iniliid raw I'ihhI up lt> ihc liiml 
** living" siiigvB, and niuvt itinnlarlr contain variuui ttaifui of wa»tc. 

{ 6. rJow, ihf- grwil cliaraclmMic of the lypicu) aoHchn (Icarin^ out ihc 
BO-'—— '- that, ■■ far ■• we mi ucertnio, all the [>hy»iii]Dgical unit* arc 
ml bU do tlH^ «nif thing*. Kach and every purt of tin- body 

r*!-. iif i—,l nun nr lew raw and builds it up into iUown livln); Kulwtancc ; 
nach aiul ttn-ry part of tlw biKlr may bf nt oiie timv ijuiwcoDt and at another 
in nntian; oadi and every part if sensilivo and rngmnds by muvvmeHt or 
albiniiaB lo varioaa ehangca in tls aitrroundini^. 

Tlte Wly of nun, in it> firet eta^c, while it in yet an ovum, if wc li^iv« 
•aiiie the nucleua Mtd Mglet't ditTerencee caused by ihc unequal distribution 
«if fotal material or yolk, may alao be raid to bo <mmpoiied uf like parts or 
like |4iT*ii>lof:ical unita. 

Br tlw art nf MffoneDtatloii, hiiwevcr, the ovum lit divided into PArLS or 
e«li* which early aDow dillurencca from each other; and these diOerenoea 
ra|tidly iiwreM* ■• ctoTelopmeut proeeeda. Some rell* put on certain ohar- 
metrr' and ntlHn Other dtanolen— thai it to May. the eell« undergo hidologi' 
»i 'iallon. AikI thit lakt* place in *iieh a way that a number ol 

eci„ :. ...,: Kigvlhrr in a group become eventually convened into a Hmha, 
and Iho whuk IhmIv boeofdM a ooltociion of such tiMn<.« arnntftiil together 
acmrdio;: to morphologtcnl lawg, rnich tiMue having a definite •tructure. its 
aallular nature Ining H>mc4iRi<« proaervcd. aomatimee o)wcun-d or ev<in loot. 

Tfaifl hisiologicikl <It8e rent iat inn h accompanied by a phyawtnt/ienl divitioH 
tflalor. Each tiaane may bo supjmeed to Ih? composed of physiologicid unilM, 
UM units of the tame tieeue being alike but difleriiig (mm the unit* of other 
tiaww ; and orrwjmniling to ihi^ditrerenceof «tnictiire, the units of ditfeniit 
li»»iia behave m act dilferently. Instead of all the units, as in tlie amo'tigi, 
daiay iIm< Kam^ things e<iually well, the units of one tinuo are told off, u it 
m^n, >' ' hiu): eH{<e«ially well, or especially fully, and thus tho whola 

labPT' i> ii divided amonK tlie several tissue*. 

rnl lissties may thu» be clnx^itied according to the work «hi«li 
ll.' . ' ' . and the Gnt great dUlinciioii is into (1) the tinues wbj«li 

■!• omovnifd in the wttio); IVm- of ener[.'y in sjx-cinl ways, and CI i the tiam«e 
whirh air ci>nccnii<d in n:pl<-ni>>hin); tl>e^ub?tan«'alldt)')rvlIening the energy 

1 :. , ivsioloftient tinSt nf tlio nmivbu while it b engaged in setting Ave 

*aar|cy an a* to move itfflf, and hy rcaum of ilv wnBitivenen so directing that 
flsatiQr as Iu jirtHluce a movamtnt vuiuble to ilio condillous of ita uurround* 

■ Sorli • ]ilijik>luK>«l «nil miflkl la e»\Ui ■ ttmm n t t . 


ingit, liANat th*> nnme time to t»-jtr ibc bibur nf uikin^ in mw foni], Qfiiclrctitig 
tliat pari «f the mw fmiil wliioh Li ii^criil mii) nycfling thut which if iisclcn, 
and of worlciiiK up ihc nccitpti^) piirl ihrnugh n vnriHv of vla^e« into It* onn 
living sub«litnce — that U In my, it hat nt tlii; Minic lim<? thnt it is lecling and 
iDoring to currj on llio wurk of <ligwting niid v«iniilating. It has, more- 
over, at the same time to throw out tbu waelo tnatterv niifiin); from tb« 
changes inking ))lum in its own substiuice, having lirsl bmuglit l)ief« waste 
nsttere into u roniiitinn »iiilnbtc< for bdng thrown out. 

§ S. Id the body of tiiiin. niovemcnts, as we shall see, are, broadlj speak- 
li)t(. parried nut by iiictiii» of niiiacnlar tii>Bue, and the cbaDfee in niuscular 
tidaue which lead to the setting free of ener)ry id ihe form of nioveiuenc are 
directed), governed, and adapted lu the surrDiiudiuus of man. by means of 
nervous lissuet. Kays of light fall on ilie uorviitis liiibataDce of the eye culled 
Ihe retina, and set up iu the retina changes which induce in the optic nerve 
other rhaiigeH, wliieli in turn are propagaled t» the bruiu as iifrvnuA iinpulst*, 
both the exdtjiliun and the propa^lioD involving an ex|iem)il.iire of enei^. 
Tbcac nervous iiupiilaes reaching the brain may iudiici- otlitr nervous im- 
pulMi w'hiob, travelling down ciTtuin nerv<« lo cerinin nninclvK, may lead to 
change* in thoae rouscW by which they suddenly gmw ^liort and pull upon 
tht MDO or other structure* to which they are attached, in which unae we 
SDT the man starla ; or the uen'oii* impulsi-» rciu'hing the brain may produce 
soniG ntlicr elTbct*. Similarly iMiuud falling on the ciir, or contact uelwecn 
tiie Hkin and snme t()reign body, or some change in the nir or other surround* 
tngs of the hodv, or Minie change wilhin the body it^rlf may w) nflcct thft 
nervous tiswie of the iKxIy that nervomt impiilM-s an Marlci and Inivcl to 
tbb point or that, to thv- brnin or cl»cwh<'rc, and evcnlunlly mny cither rcJwh 
•ome niii-H-uhir tinuc and ko gira riM to movements, or may reach Oth 
ti»ues and )>r<>iJuce some other eflf^ 

The muscular ti«8U0 then may be conndered as given up to the production 
of muveiuenl, and the nervous tifeiio nt given up lo the generation, tranil'or- 
mnttim, and propagation of nervous impulses. In each case there is an 
expenditure of ener>;y. which in the ease of the muscle, as we ^ball see, leave* 
the bodv partly as heat, and partly as work done, but in the case of nervous 
tlaaiie is wholly or almost wholly transformed into heal before it leaves the 
bodj; and thtH expenditure necessitates a replenishment of tatergy and a 
lenewid of .lulistanoe. 

§ 9. In onler thnt these master tissues, the nervous and miisoutar tissues,, 
may carry oii their important works to the best wlvauiage. they are relieved 
of much of the labor that falls upon each physiological unit of the amicba. 
Tfaej are not pre^iited with mw food, they are not required to carry out tha 
neonniry tranifunuutioDS of their immediate waste matter*. TIk whole uf 
the nst of the body is engaged (I) in so preparing the mw fooil. and u 
bringing it lo tin* nervous and muscular tissuw that may build it up 
into their own solmtamv with the least trouble, and (2) in receiving the 
vraste matters whiih arm- tn muscular and ner\-ous tismea, and preparing 
them for rapid and easy eji-cliun from the bmly. 

Thus to ocrliiin liwrno, nlncb ne may siH-iik of bnindly as "tiwues 
digestion," is allotted lh<' duty (>f acting un Ine fiiod and pn-puring it for tha 
use of the muscular and m-rvouj tiiuues; and to other tiiuu<'-'>, which wn maf 
apeak of as "tinaes of excretion." i" alloiied the duty of clcnriug the bwly 
from the waste mattera geiicrnlrtl hy the muscular and ucn'nn:^ liisucs. 

^ 10. Thew tisauea are for the mcnt part arrange)] in machine or rarcban> 
isms called organs, and the working of ihiawor^ns tnvii|vi:i> movement. The 
maveroeniB of then orgnn« arc carried out, lilce the other movements nf the 
body, chieflj by means of muscular tiaiuc governed by nervous tissue. 






B<f><v or may nixkc ■ dwliDclion betireco tlie niuscla wluck ar« coDoerued 
in pfTialdciu); ■» elfcci gii the world ouuitlo man's bodj, the muBclce by wbkh 
MM il<na nt« imrk io the norld, anil ilw nituotei which nre oonoerDod iu 
snrinK <Mt th« raovemeota or the ioteraa) orgaiia. Aiid we ma^ atmilarly 
■ako ■ •litUucLinn belweeo tbi- nervous tissue concemeil in citrrying oul the 
alerokl work of tbe body aud Ibat coawmed iu re^u'ttinK the moreineuta 
■ad, M we sbftll see. the general conduct of the interiiul ur^is. But rheM 
t«o clawei uf muscular and nervou* tiMue Lh<>U|;h dUtinct ui work, ami, lu 
M shall see, ofleti diflereot in structure, are nut nejinnited or isolated. On 
llw CDDtrary, while it is the main duly uf tk« nervous tissue as a whole, the 
wrmw system, an we may call il, tu carry oul, by means of nervous impulsus 

raiag bitber and thitlier, what may be spoken of as llie work of miin. iirul 
this aanw is tlie master linue, it abo serves as n bond of union liiitwiTO 
itwlf and th«' muscka doing external work on the one hiind, and the organs 
if digaatioD or excretion on tlw olher. mi that (be iictivily anil comlocl nf 
iW laurr may b>' iwloquntcly udiipttd In tbi- iieedii of the former. 

( U. I.^utly. tbe fiHid jirepirpd bikI i- In bo rated by the digestive urgiuin is 
arriad nod preMnlcd to the musouhir imd nervous titsuea m the form of a 
tfMnfdax fluid known as blood, whit-h. driviMi by incana of a compIical«d 
ikrrhantsn) known a* tlic vascular apleni, circulatea all over ifae body, viitit- 
iuf in turn all the tiwuct of the body, nod br a Kpccial nrraiiceioont known 
m Iba rwpiralory Riix-hanism. carrying in itM^lf to the sovvnil tusum a supply 
•f aiygcn as woll as of food mnro properly so callod. 

Tbn motive power of this vascular system is supplied, as in the case of the 
figMtiw system, by means of muscular tiwue. the activity of which i* sinii- 
bnjr governed by the nervous syslem, and hence the lloa- of blood to this 
jtn or that pari is rO|i;iilaleil sccordinK to the n«eds of the pari. 

f U. The above alii;bt sketch will perhaps suflice to show not only how 
saaieroas but how varied are the problems with wliich physiology bos to 

la ibr fini pln<« there are what mity be eallol jceiienil problems, suob aa 
Uoa tbr f H«l nltrr its preiianiti'iii and idulKirntiou into bloiul is built up 
isfi Itic living outwtnuce of the several ItMuc? How the living sulMtiinoe 
bnaki down into lh« deail niiotc? Huw the building up and breaking 
4nm liithr in tbc diH^ront tissues in such a way that energy i« set free in 
dftrvat mode*, the rauscubir tissue contracting, tlie nervous timuc thrilling 
•kb a oervotis im|HiUc, tbc secreting ti»iie doing cbeniicnl work, and the 
Eke? Til tbaso eeucnl 4U(»tions the an»wcn which we can nt present give 
can banlly Im called answors at all. 

la the serond place there nre what may be called special problems, sueb 
as What are the various steps by which the blood is kept rvplcnishcl with 
bod aud oxygen, and kept free from an occumulalioa of ffaat«, and how is 
tbr anirity of the digwtive. respiratory, and excretory oigans, whicli eJTeot 
Ibta, rv-ifulsled and adapted to the stress of drcuntstances? What aro the 
detail* "f <be working of tlw vascnlnr meclitini^ni by which each and every 
IIMM b fc««ver baihed with fresh blDo<l. and how i» that working delicutely 
adaftad lo all the varied ebanKes of the bodyT And, compared with which 
■U oOwr special probleou are iu^ik'nitioaut and preparatory only. How do 
mn aut impubes so flit to and (r^ within the nervous svstem aa to issue to 
tbe movements which muke uii what we aoraelimes call tVe life of man? It 
is la ihtve special jtrobleni.t llmt ne must obieily confine our attenttou, aud 
«• may fitly begin with a study of tbc blood. 

BOOK r. 






its. Ttie wvrnl linur* nm Iriivcnni bv inhiuio tubes, iIk c*)iil)arv 
l>loedv«a•cl^ u> whicb blood i* brought by 'th« Mlvrirs, bik) frcnn nhicn 
blood y Muriwl Kiiiiy by ilw veiiw. Tlww cntiillnrin' f«ni> ncivorka ilw 
■ w fcr * of itbich. rlirU'rins in rortii nnd riw in ibc diltvn-Hl ltnuo«. arc oceu- 
pM by ibr clrmpiiK oi Inc tJMUO irhkh coiweijiJCDlly liv mihidf ih« Mfnl* 

Tbr hliHi't flowing through Ihii cniiillnrin coiisut*. under tiorirml com)!- 
lioiM, of an uliDoat «o1orle» fluid, tbe filaiwa, in which are carried n tium- 
btr «f bodin, th« r*tl, «nd the u-hiu (x/rfnurtf. OuiBtde the vapillary wnlls, 
fiKngnpHich ■[incnoa exist beiwceii the capillary valla and Ihecelln or (ibiee 
sf Iba tiKiic, or belweeii tbe eleuitnis uf tbe tiMue lh«iiii»elrea, is fomiil ft 
«okir)Ma fluid, reAcniblinj; in niaoy m>iN.ft» ilic pliuina of blood and called 
tfmpli. TliuM nil (Kb elements uf th« tu*uc and the outfidn of nil iht^ nijiil- 
MTW« arc li«tlM><) nilb lyinjib. uhirb, a* wcslwll «ce bcrraftvr. i* continimlly 
Aowioir annr from ihc tlvtic alonif i>|Nxial chaiineU lo (MM into lymphatic 
VOMela ami ihmi-v iiilo ibe blixid. 

As thr bliMKl tliiwR ihmu^b ihr cnpillaripf certain ciinfiitunils of tbe 
phunin Mogvlher wilb, al tiium, nhttc ixiriniK-le*. and under t'seeiilinDal 
cirruni*lannii red c(ir]>itft(rK-« i pBM through tbp c«|>illnrT nail into the 
lynjih, and crrlniu i:on«liiuciilt> of ibr lymph pnM tbruugb the mpillwry 
«all into ihr blmwl Miiliiu tbe enpillnry. Thero is ihiie an iitlcrehango uf 
Matirrial b<'l«i-cii the Mood wilbiu the mpiltary and the Irniph oiil#idc. A 
•imilar inli-rchBii^ of material if at the Ftiine (iine B'^nj; oti betweeo tbe 
Unipb nuil tbo tiMUe ilwlf Ueuoe. by nicuno of the Tympli nrting at mid- 
atrman, ■ diwihle inierehsMKe uf maleriiil takes place beineen lh« blood 
■itbia tl»F nipillary atid llie It^xite Kiitsi'Ie the capillary. In every li»ue, 
•1 bioi; as life lasts and the lili«<il flows lhruii|;h the bl«<>dveHeli). a double 
(■T*«tn. anw mpid. n«u filowr, is |iat»iii); Irum the blood to tbe Ibeue and 
fmu ibe tissue 1» the bliHul. The sireaiii IW>ui the blood to tbe tusue car- 
tir* to ibe liMin- ibr nial'rinl nhich the tinue needs for buildini; itf>elf up 
amt f'f iIjiUii; it.- work, iiirtiidiii^' the all-imporlani oxygeu. The stream 
fr : atue to the btoml rarrin< ii>t<i the hhiod t^riain of the products of 

it. ... cbaiigva which havr b(-('ii taking' plaeti in iho luiue, pnxlurta 

■bkb mar he simple vtaMe. to be oM otit of the budv as soon as powlble, 
•r which may bv budin ca{>nble uf bfitig mn<le txK at by aome oUier tisauc 

1/ IH.'i'ili. 

A iliii'l Kifiitiii, ilini IV'tiu lli'T lyififili lyiii;; in tli>r rhinks and craoQiee of 

III' li> 1 iil'iHtr ll'i' Iv'l'l' <'liFinrii']4 t<> tin: lur(;t;r l_vm[>b vessels, carried 

Mwiiy li'iiii llii' lii'iii'T >^<ii')i |iiirlK 'if ill'! iiiiiUiriiil coining from the blood as 
till iikJ iiiti'ii iiji liy till' lir.'ii'' iiri^ir iiri'l Midi |>iirti^ of the material coming 
tiitiii ill' lirn'ii iiR il'i ji'il liiid llii-ir U'li} itil" tin: hloiMlveflsel. 

Ill tiiii'-i I iniiii'", iin ill iiiii-i'ji- fur inntiuiftf-, the capillarv' network is bo 
I liiwi ml iiii'l ilii' iiiiini'iiliir liltrii li'-M HO nimr to the bloodvessel that the 
lyiii|ili liiliv'i'ii til'' lwoc\i>ilN onlv iiM II viTy thin nheet; but in some tis- 
BiiKM, (in III iiiiiilii)t<', ill'' lilci'irlv'iv'-lN lir nil ihu oiitttide of a large mass of 
tlMii". Ihi' IiiIi'H'Ijiiiik" Im'Iwi'ii the ri>iilritl jiiirlH of which and tne nearest 

i<ti|'lll'ii V I'l Ivcnni'l in I'lii-rii'il 'in throU|;h a liin^ stretch of lymph paBsages. 

Mill III I'li'li I'lini' lliii iiriiii'i)il>' in tlii' niiik-; the tissue, by the help of lymph, 
^iii 1 "11 Ihi l'lii\«l : iiii'l nlii'ii ill Hiiirifiliiiir pu^eii wc speak of changes oe- 
liiriiii llii> liliiiiil mill till' liHNiii'H, il will be iiiidi'rstoud, whether expressly 
al'ili'd ml 111 ii>i[, tliiii llii< i>hiiii;;ii< iiri' cUt'cli-'l by moans iif the lymph. The 
bli'iiil iiiii\ tliiii Ih' ri'fviiiti'il iiH 1(11 iiilrni-if iii-'iliiini, benrtng the same rela- 
Mmin 111 lliii r.<iiiiili)i'iit lix.iiK'* llmt the cxlcrniil miHtium. the world, does to 
(lii> »liii|i> nutitiiliiiil. .liiM 11^ l1u> whole nrj^tiiiiein lives on the things 
iiixiiiiil ii, 111 lilt mill \i^ I'lHul. HO ihi' si'ViTiil iiiu>iii>it livo on the complex fluid 
lit uliwli ilii't iiiv nil liiiihi'il tiiiil whii'h is Co ihcm their imme«liate air and 

( I 

\n ili<< ii»uiv> t ikt' M)> i-wp'ii iVi'iii ibi' bWd and fi\t' up carbonic acid 
III ili>' l>li-.',l, biU iu<< ii1».t>it III ibi- s.-uiii' r.iic or At the $ame liiue. More- 
I'v.t t!i.' v'M'i^ii iiwii.s l.iki' i!|' iV-'iii ilio li!.hi.i and j;ive up to the bloid 
vi/i.i .1 ilvivir, tilings .'v liu- 'ii:!!!- tbitip^ a: diilVwiit nttw or at difierent 

■.\w ^•■■•c ::A\:<i. :h:i: ti'.o ivuuv«ii:i->ii and ohsrac- 

'"••.\Atr i.irx;;-; iv, .lir^Vrv:;; -.•arts ol tiie l»iy and 

:■.• .-I'u- ■:'.:<." i. :.-V. :\:c :.::.:ii ai,i! a >f all the 

-'■, s", •; ■■.;*■.•..,■(:■■. a:: .iv:-i_ir ■-■^::'.r'u i.''ai>.'eitii>o 

V ■-■ ».vv il s''.:*:'.^,> «!-. ■..">. b'. ■•>i s tn.iwn t>i 

■ .; ■ '-.■ «,-\trr*'. ;;**:;>»■-".'. xj; "x- waI: with 

1 .(■■■. \;-.i:- ,■■■.;■ -v.Ut : :.t .-;i*i:i«li:cL At 

. ^ ■. .■,■ ■:.:\-.-. ■'iJi'.:'>.-i <: ;!i a-^ rn»eat«il 

\.iv ■■..■ *>„',;;■ .i i-:j. ,.-r-:i : - ;i-; i.amya 

-.^ • 1.1-. . "■; ".■ K K-.t 7^ -.:' Z--C rj)i ai-.-K im- 


■,\**" ; ■ "H ', 

*'••* .'X**. **:* 

u* ■• 

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\^ ,A"'l *■■^ 

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•-{ ;/ o> i> 


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' tv* ,' ■ \- 

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' 'ilV*l,'^ 

i ',* ■ !• . 1 I. ■■ ■^■■- :.■..■" ;>!»;■» i' t 'i^ I'd" » wrwrtLT 

' ■ 1 . ^' , ^ -s ■.■ • x". ■.■!*. -Mi;;." -T-iia -- .-ii g m w 

"•1 T^ - :-»-■ ■■: . . ••: \ ;■ . ■ 'l.a* l' ll'^i-I lOtUr 

'-* ■ • -■ '":' .!«* : ■ i::i,'j r i-j» it—a sded 

--'_■■. « ■ :■ ,'■ : ^Hlic *J.'iiL I^bi 

< .' ■ -•..:■. 1,; : ; -ii-*ri;l" suUtKi 

■ ■«. . - . ..^ - .^^j. _ \ ^ i_' ^ 

_ ,1 ,-.:>? «s*-. 1 -fci* iriD* 

- — - - ~.-- - ; ;:v -i.:-^*: -t rhe 

- , ^ _~ ■■"...- "? i>TfcJ- i T-uin 

- . -- . .:, -sa liT a-fr^ 

-->:.■- -.-Tj. 1 ■•■■iC 



«r ArttMam<n/M«i, flonting in n |i«r(ectU fluli] xrruui. [Pig. 3.] Th« thriiikiug 
•ad owMkoMtiou of tbe clot, luid lh« (virrtvpoiidiiii; iRoraaM of thr wTiim, 
PMtipM fiir aune tiia& TIm- iiivikt Mirfiui- of ihi- clot b g«D«rnll}- Hli^htly 

[TM. 1 

;»!■. a, 

>t dT (viwnllir tomoUM Uaid, 

Unwl nt ■BnipiliiU'l tiluil. arm laotrv 
liiK In tlH) ADid (MVui. Al)*t I'lLiulcl 

Me<«va. A porUoD of lh« clot vxamincd under t)i« laionwcopo ia MW (o 

oMMiK of « n-Uwork of 6n« gniiiulnr fibrils, iu lti« niMhw of whicb an 

mtaafUd tlM' ml aii<l wliiie ovrpiui'lM of the bloo<l. la the mnim iiothipg 

(Ml be ae«n but a few stntf curpui- 

tim. chiefly white. Tbe MbriU «ro l>^" * 

cnrapoaed of a hi balance nllecl 

/kritk. (Fm. ■!.] Ileiicc we m»j 

•{M«k of ihe ulot u coDakling of 

Abrin and corpusclei; an) ibe act 

of duUine Is obvioaily a Buwtitu- 

tm Ibr tno planna of AbriD ami 

arav. ftillonnj by a acpaimtioo of 

tbi fibrin aiul «>T|iuaclei ffura the 

OnfUtiMd aiola. *lM<rti>t Ik nbrltteul mq- 
dMIOB. AAm Dauok-J 

^> Ib nan, blow] when *b«d bocninat 
Tiarid in about tww or ihn-o iiiinutut, 
«mI «Dlrn tbp jvlly tin^} in nbiitit 
irvur ten minutes. AOi^r tlie lapM 

■ of anaiher few tninuton the lint 
ditipi itf BcniBi areeeeD.nnd dolling 
ii gUimally cotunlelc in fmin o4ie to 
ivmal boun. The (ime, however. 

■ win Iw found lo vary acoarding lo 
(ireuBMHoceo. AmoD^ anitnali tbe 
npidity uf duttiug vanm excee^ii);;ly in iliHerenl speeixM. The blood of tbe 
bom clut4 with reiDsrkable alowoeMt; at) bIdwIv. indwd. that many of the 
rod and alw loDie of the white corpuscles (botli tbeae being Bpecifi<'ally 
bearirr than the plasma) bare litue to Mnk before viscidity aets iu. In con* 
sa^MHim ihara ainirmii nn tlwsur&oe of the blond an up|>er layer of oolorieas 
fhfift. oMOt^nlng In its dwper panions many c»ii>rl«s9 corpiuclat (which 
an lighter ihnn the r*il>. 'lliis Uycr rlntu liki- t)ic ntlwr |«na iif the hlood, 
fcrolnff th« »i>'Ciill<vl " butTv I'nai." A ainiiliir butTy cunt i* Mimfitiiucs Mvn 
ta thr bl'--l of Minn, !n o-riuin atmurmni rnuilitiom ot tli« body. 

If a [K-ttioii of txirwV hl'Mx) lie mimmndcd by a cooling miilur* of Ec* 
aad mil, and thiu krpt nt ntmut il" C, clotting may benlmoot indefiniloly 
puMponoJ. Under ih'we cin-urasluoeo* n iu»rt' oompltM (lesccut of the cor- 
[WIN 111 takue pliu-c. imd a oontfalraabK- iiuiinlity of oolorlus traniparvat 
froe from blood oorjnwpka may be ohlulnetL A |mftion uf this 


piiumn rctDOved fmrn the ftvninn uiUtiire dnU tii tbc *IUM manDrr u (liit« 
the vnlirv Ulo'nl. It firal bcomiat vim-id nnil i1i«d forma n jelly, which sub- 
■•qiiOtiUy M-fiaintfs into n oolorlcM akruukeit clot oui) acriini. Tliicahow* 
thnt iIm) niriiijuclet nrc not an caeniial pitn nr the c1a|. 

It a few cubic rpntimrircf of chi« oolorltw plHtiina, or ofa niniiUr plMma 
which tnnr Im' ohuiiiivd fnim nlmwt nay blixxl hy menm n'bich we will 
pmcntly 'JM^TiliO. I>c ililuU-il with m«iij- liin« il« bulk of n <t.W per wni. 
tnluli'Mi of Hixliuin chloride' clotliiig i» much rcUinliyl, iiiiil iho vnHoiig stages 
Rutv Im) infirv Muily wMcbwl. A» the Itiiiil i* bivomin^ ricci'l, lino fibrils 
of Alirin will b« Men to bo dovel»|>t.-il in il, cs|*cctully nt the hJc« of cbe con- 
lniniii(,' vM*al. As tiioM fibril* multiply in iiutnltiT. the tloiil becomes more 
nn<l tii'ir>'i>f (he i^nsistcncfof u jelly nnd st the Mime time somewhat opaque. 
Klirntl or pulh^ nbuut uitli n needle, the libril§ shrink up into a arnall 
o|iiii|iie Htriogjr iDlin; and n very eoDHideruble bulk of the jelly may by 
n};itikliuii b« reeolved into n mimite frnj^menl of ■lirunkeii fibrin ilotilin); in h 
(((lantiiy of what t§ really diluted serum. If a Bf>ecimen of such diluted 
plaamn ho stirred I'runi time to time, as soon ua clotting begins, with a needle 
or gliUM rod, the nhriii may be removed piecemeal as it fornix, and the jelly 
•ta^- tiiay he ult'i^uther done away with. When fresh blood which has not 
yi-t hnd time |i> clot U xlirrwl ur whi|i|>eil with a bundle of rods (or anything 
proMUlinj; n InrKu umotini ot ruut;li aurfaeet, no jellydike clotting take* 
plaoot Itiit till' mdit liceomo covered with a mnsa of tikrunketi fibrin. Blood 
thiia whip|>eii until lihrin ccniHW to be deposited, is found to have entirely 
\iM l\M (lowcr >)f cl'itling. 

I'utling tlie»e fuels logollier. it i* very clear tlini th« phciiomnia of 
the clotlini; of blood arc cnutcd by the apjieurance in the pliwmn of fine 
flbrila of fibrin. S<i hm^ a" thaw ar« «ciuity, the bUicKl i* ximply vixoid. 
Wh«U they ticcomc siiHicieiilly numerous, they eiv<- the blood the firmness 
of a j'<Uy. Soon nller ll)eir rurmnli<ii] they Dcgin to shrink, and while 
shrinkiti); endow in llwir um»Imw the corpu«cle«. but squeeze out the fluid 
parts of ih» bItHK). llenc« the appearance of the shrunken colored clot and 
tlw cidorli<eB scrum. 

5 13. Kilirin, whether «I>tuit>ed hy whipping freshly sbed blood, or by 
wiuihiiig cilhcr a uormni clot, or a clot obtained from oulorleM piaBtna. 
exhibits the Mme ti^-ncral cltaractera. It beloajn to that olasi nf complex 
utMiable niirDgvDous btHltrv railed protrid*. wbien form a tarjce portioD of all 
liviiit; iNMlins bimI an uwntiid jiaH of all living stnidurea. 

Our kmiwlnlge of pn>teida v- at pnwent too inii>erfecf, and pmbahly nam 
of thvni have yet Ix'cn |>n-]Mml iu mUijuate purity to justify in in nltemptiiig 
to Mvun '■> lliem any drtinilc fnrmuU ; but it is imptirtani to renieinbet ibeir 
gtatnu ci>ii>l>>isiti'>n. UK) |iart> of a pn>tetd enmiaJu miher roon- than &0 
pans 1^ cnrlxia, rather ntun than IS of ntuugco, about 7 of hydragvo, and 
rather uorv than M of oxygen : that is to ny. tber eootain about £Uf their 
wdsrht of carboii, and uoir about i iMr w^'glit t^ nitmgai : aul vet, m wc 
■ImIi m«, tbav are emioenuy lb* iutn«nious HibMAucnt of ibe b»dy. They 
wwllycaM^ aHHtllqitaalirf (I orz per cvnL) of sulphur, and manvalso 
h«** mmt pkuiplMraa attariwn lo Ibaaa m sobm way or other. When norot 
Umv Wra • wiaUe «|aaaUiy of aah, mtMStine of inorganic mite of whicb 
iWrh— MS cMeir aoJiwn and poOHmtn. and tne ncMe chiefly hydrochloric. 

ilwy all i ^i w cMtain f«ni.liWM. by whicb their prMence may be neo^ited ; 
of tbtw iW mtm tbniafirrirt ai« tfae folloains : Bnikil with aitnc and 
ikay gin a y al h w eUar, «fckb iiw |gM a iaiw ««<uige upon the ndditiaa of 





■awooim. Tbil k cklted ihr xanthitproiiiie t«st ; the color h due lo a product 
of iMunipMJUOn. Bt^leil witli llto mixture of lOPKuric anil iiiercurous 
Dimtra kiiowB M Millim't r'-aynt, Ihcv |pvc n pink wlor. Mixed nilli n 
alroaf; •olmii-n of ^ndii-bviinUi- tln-vgivp. cm ihr nddiliun of a dnn>»r two (\f 
m wvy ««ik s-dutiuii of cuprii' Hiil|itial(% n viokt or pink color uliiuii def|M'DK 
oaMUiag. Tbcw nn- aniliml rt-acliunK, nut ttir'>uiti): tuui:)i if aor liubt 
anlbtCUOMilMlioDuf proU'itU; bitl llit-y nrr iieclul as praclii-al lr«u ctinblt'ng 
oa U> tiMcct llii-ir pmejica. 

TIn Mvcnl mrmbon tif the pruidd group iiro at prmeiit diRtingtibbod 
Ai^ tadi tUfaoT chit'tl^ \ty thdr rn>{wctive aolubilities, ee[»eciajly in viiriuiti 
■tUaa atlutinna. Fibnn i» one n{ the l«uM enliible ; it is iotoluble in wKlvr, 
■JiwMt insidiiblr in dilute itciilnt) Hti1in« solittione, aud rerv npuringlir wuIiiUb 
IB nmns coon-nlrutw) neiitnil HiliDc tototioiis niid in dilule acide and tlkAlwi. 
In (tniDK acids aud alkaliM it diasolrea, but in ibe procNa beooiDCi mn- 
plaUljr cnaogcd into Bomelhio;; which is nu luiiKer fibrin. In dilute iicMf it 
•■■Ik up and l)«<<(>ni«B trains pArcnt, but nben tbe acid ia neuLratized rMunia 
Iji Its pivTioufl cunditiuii. Wlxrn suBpendc<l in water and liciited lo tOO* C, 
or crm to To" C, it beconwa ch«i)|j[Ml, and Hiill leut Mduble ihtui tx-foro ; it it 
M*d JD tliit tmm> la be eoagnlatnl l>y tUe beat, aiid, ha we «ball mc, nearly nil 
|MH«Ua bav« the prujierty '>f beiiiji chaujii-d iu iiatuiv, of uodorsoiDg 
OMjCtiUtion and ao Itpcimiiig leM aoluble than bcforn, hy being cxpoaea lo a 
Mrtain hi|;b tt^>ii|H'r»tiire. 

f'itirin, tbfii, ia a protvid dUtingublietl from oilier proteidii by itK cmallcr 
wlubility; it i* fiirlber dialiufcunbed by itc iM>ctiliar iilainiMitod* stnict- 
oiv, thv c4bL-r jiroleida when oliliiinefl in a •olid foroi appearing either in 
aotorvbou* granulr* or, at miMl, in rUcid masKa. 

I If. W« may now n-lum m the tmim. 

Tbia b perfectly fldid, nnd rcmniRi duid until it deconinoeee. It ia of a 
ftint ttmnculor, dueto the pirsencoof a special pigment subatUDoe, diflering 
frun lh«' red niiilter wbicb Rives red»e» to the red corpusclea. 

Tmed by iIh- xanthoproteic am] other lots it obvioUBlr ountitinii n Urge 
mtantiij of proteid uatler, ami upon exnniiiuition ire flDa llial at Imat two 
iliaiioei prulind Mibatanoea arc preaeot in it. 

If rry*tnb of magnesium sulphate !>« added tn Aenim and gv^ntly atirrt^ 
uaiil ihny divanlvc, Jl will be iteen that thi.- »eruni att it appn«cht» uitumiion 
tritb tbv Mlt lieconea turbid itutead uf renniiiiiu),' clear, n»d «veiiltialiy a 
vhtir amor^dtiiiM frnuiular nr flooculeni pn-4-i|iiIit|i-- uiakM Jt.i ap|M-iiriincr. 
Thi> pn.-c>pttatt' tntiy Ix- MiKiraifxl by dvcautaliun Dr BUratiou, waabud witli 
iaiamtnt MiliitiouH nl' mtiv'i !•''■■ ■"■i lulpbate, in nhicli it iit inaolubic, until it 
ia frwl fniui idt 'ilbcr I'lnntituciitit of lh« leruiD, and ibufl obtaimil Ibirly 
INirr. It ia llwn fmjtid ui Iw a proteid IhhIy, dittiuguiabiil by ihv liiljowiiig 
riiaractvni iimoiig oibi-n: 

1, It in (kIii-h I'rtM-d fnim iiny iidherciit nuigoij^luni Milphalc) iutnlubh) in 
■lialill**! waiir; it i* inxiliiliU^ in onft-niriiHnj xilutlona of iwutraj Balinc 
bodin. Mit'h a* mngnniiitn ■ulphnt'^, Mxlium i'hluride,Me.,bul rMdily aolublo 
to dilute ('. y,, 1 |>er M'Ot.i M>lution« of ihc naine n4>uiral Mdiuc boiliee. 
Iliftrr fniiD it* »oluli(Hi» iu the latter il mav l>e prrcipit«tv<l vitbfr by adding 
tnnre aeiitral Mline sulwtnum ur by removing bv dialyaia tlM muall ijuantity 
„f .,i;.,.. i^jljatBtir-e prexent. Who'll i)t»laiiMd in a prccipitaWd Jorrii, and 
* : in (liidilltNl water, it readily dixwilve* into a clear solution upon 

ibrBo.iiMtiiirasiDall •i^tinntity of soiiK'iK'Ulral saline bixiy. Hy t bene various 
^utiond and jirr4.'ipiljilKi»s it is not n-aliy ehaiigod in nature. 

'i. Il rrndily ilim-ilves in very dilute acide {r.i/ .'m h^ilrwlilorie aetd neo 
wbefi (liltneil to far Ivm than I jier cent.), and il ■« •innliirly Milubic in diluio 
aikaliQ*, but ill Iwing ibas dissolved it is irbolly cbangv<) iii nature, and the 


B 1.000. 

B<>liilii>ns of h in diltile acitl nnd dilute sHulics eiv* rcai-ttons quite dtdoi ___ 
frDiti i.l)u§G •>{ tho suliitioii of llie siibetance in dilute npuiral snliue wdiitiooi.-- 
Ity tlic acid it is ooiivcrled inLo nliat is c&llod (ici(/-u//i((riiin, liy ll>e alkali 
iuto alkiili-'tlbumin. butik of wliicb bodiei ve shall hiive to Hludy later on. 

'i. Wben it b suspended in wnter and healed ii becomca altered in cliar- 
acter, mai/ulatrJ. aud nil its reuctions are chaujred. It ia no loDger aolulile 
in dilute iiviitiid aaliue solutioiis, nut even in dilute acida and idkulie*; it 
haa bceoQit; coatittfaltd protxid, and in now even less eoluble than fn-fii fibrin. 
When a loluiiou of it in dilute neutral aalioc eoluiiou id Nimilarly ItcBtcd. a 
•iinilar cbonge lakea pliieo, n [ireeipiiale falla down which mi cxaminiiUon 
if fi)un<l to hv cungulnlL-d pmteiO. Tile iciiijionitiirc at which l)ii« changD 
tnkts |>lac« ia sumewberu nboiit T-t~ C, though nhilling itlighcl)' acoMrding to 
the (]uantity i)f nnliiie Kubttnncv prment in Uic Koltitinn. 

Tlicntirive |.bn.-i.' ruactiunii arn given by n nuinlipruf protctd b<:)dies foninn^ 
m griiup cullfd alohulint, tind the [lurliciiliir gtohulii) pra«cnt in blood-eenim 
is vuUvd jiaraijlohnliu. 

One i>r Ihc pniii'id* prenent in blood m runt in then pariiglnbulin, charac- 
lerixeil by its »i)liibility in dilute neutral Mlinv x>Iution«, ii» in»oIubiliiy in 
dietilird wnter nnd co u <.■<.■ n I ratol wiline colutiouF, its n-iulv Mtlubility. and at 
ibe Himc time convcreiun into other bodies, in dilute acida and alkalictt. and 
ID iia becutuing convertml into coagidatcd proteid, and «o beut]; precipitated 
fVom its GoKitiun* at 7<>° C- 

The BDifliint of it present iti blood-serum varies in ritrious animalB, am) 
apparently in the same animal at diflerent timts. In 1U[> ports by weight of 
serum there are penerally present about 8 or 9 parts of proields altogether, 
and of these some 3 or 4, more or less, may be taken as para|;)obulin. 

§ 17. If the serum from which the parajilobutin has been pivcipitated t>^ 
the addition of neutral .lult, and removed by tiltrstiun, be subjected to dia- 
lysi*. the valt added may b<! remiivi-d, and a clear, Mmewhal dilute*) mtnim 
free from iiaraglobtiliii may be obtivinetl. 

This still gives abundant pniteid rvuicliouH, ko that the xerum Mill coataioa 
a proteid. nr wuiie proteidv *lill more mdiiblc than the globulins, since they 
will remain in sidultou, nnd nrc n-'l pn-cipitatrd, even when dialyia is con- 
tiinicd until thi- nriim is pructitnlly frx-rd from both the nuutnd mIi added 
to it lutd the dilTuaiblc hiIis previously present in ibe natural fenini. 

When this scrum is hcnleil to T')" L'. a precipitate mokes iU appearanco; 
the prolcids still present arc caa(;iitalcd at this temperature. 

\\ c have some reasons for thinking that more thnn one prnteid is present, 
but ihey are all clowly allied to each other, and wc may for the prveciil 
speak of them as if they ueie one, and call the proteid loft in scrum, afler 
removal of the paraglobuliii. by the name of alhunn'n, or, to diatingiiish it 
from other albumins found elsewhere, rmnn-aibuinin. Serum -a I bum in is 
diiJtlnguifihed by being more soluble than the globulins, since it is soluble tn 
distilled water, even in the absence of all neutral salts. Like the globulins, 
though with much lets eoue, it ia converted by dilute acids and dilute alkalies 
iuluacid-or into atkati-albumin. The percentage amount of senim-albumin 
ill xtrum may be put donn as 4 or o, more or less, but it varien and some- 
limcd io l<Mi abundant ihaiipaiaglobulin. luBomeanimala (suak<»)it is said 
to dirapjit-iir during Marvation. 

TIh' more imp'irinnt chiiraclcnt of the throe pmteids wbioh we have jiial 
ttitdicd may l>c atati^d a^ lolluu'ii: 

BoIiiMb til <li>tlllf4 wklor bdiI In mIidc t-iluli<inf of nil ^IreuElli* - nenin-aUiimi* 
InKiliiMr in ilidiUt^t walxr, nodll/ riliiUto inililiil* (alin^ KtlnUcin*, 

Intvtiitl* lu omcaiiiraidl •iillno mliiUoDa paragbtMim. 

tnioliiMa ID illitlllnl wjilcr. Ii-ir^llr iviuMa at sll id ililiiU aUfno 
KiluUon*. an4 vvr; tliUatuIuUsIn nraiv (OdivntraiMl mIIuohiIu' 
tko* .iftria. 











Bndiln (inniglobiilln slid ecru lu-al bum iit, wruin couiniiM ii'verjr luge 
n ■!■!>■ f nf subMuDCM, f^enernlly iii mduII <iiiiiut!(r, wliicli. miico tki^ )iiit« 
to b* ntnMlt«) hy b|«cibI n>vth(><ls arc i-ailetl txtracliK": of lli«#c tti'mc U« 
Mtr<i1t*onu>, anioe noD-aiirogeooti*. .Serum vi>ntaiii> boridca i»)|Mttaiit iiior- 
(snir HtitK* mlwtaDcn: but lo th<9« ire duitl n-lunt. 

t IS. With the knuwlttl^L' wbifh we liavegaiwil ofllH- iiroirtdn ofcIiKltiJ 
bloi^ wr mav e*) t>a<.'k to Uw 'iix-MlioH : Clotting Wing (liii* In (he ai>iirnr< 
aiK« in bliMxl |iln--iiiii «t' a proteiil MibslADCC, liliriii, vthU-li iitvvuiii^Iv din not 
tairt in it aa w-h. w hm an- iliv miisM whldi Inl f > l)iv ni>|>Mirniirc of Hbrin t 

W« Irani MiniHtiiiif; bv ndidying llii> iui«t ini|iiirrniil irxUToal ciiviim- 
Maneat which aircci ibi.- rapidity niili which Uw blutxl ul' lli« sain« indirtiluat 
dstt mhto thcd. Thm! arc m Ibllowa: 

A uiDpt>ntmvnr'10° C xhidi b aboul or fllgbtly «bo\-f> tho tempemlure 
of lb* Uoorf »f KHrni-bliMdcd anrnwl^. la |>i.Tlin[« the moM favorable lo clot- 
tiag. A Airllwr n*t> of a few dterMs i* ii^i|<arcntl}r alio bcii«6cial, or at 
toM sol Injiirimii ; btlt upon a eliirriirthcr tw lh« rHc«t chancn, and when 
bleed ii npidly heated to M^ C do cluUing nl all mav Ukc gtlBce. At this 
iMBpoMurt evrtain pmMidsof tbv IiIwhI an oungufntcd and prMJpiiaied 
h^on elcUioc i-aii laao iJacr-, and With this cbaage tbc power of the blo«xl 
to clot is whMly hwt. ir, hoWL'Tcr, the hcaliDg be not very rapid, tho blood 
naijr clot bcforv this changD hns time to cone on. When ihe (emperatore 
ioalcad uf being miM^I is lowered below i.0' C tliir cloltinj' l)e<x>Ttiee d«layeil 
aail pmlongeil ; and at the lenipenilure of 0° or 1" C. the Mood will r«maiji 
flaid, and yvt capable of clollin^^ whi^o willidrawn from llic adverec drcuin- 
■cuwca, for • rtrt lonf*. it niit;ht alaraat be aaid, for an indefinite lime. 

A (cnall quantity of hhMid ihcd into a small vewel clote sooner than a large 

■ onsMity •htil into a larger <>»e ; and in general the greater tbc amount of 
Ml ail n furrncc with which the blood conxw in I'vniait tlw more rapid ihc 
dnUtBg. y>'htu vhrd blood i* Mlrrcd or "u'hip[N.-d" the fibrin niakca its 
■ppMrance mh-imt than when the blood n Icll l» clot in tbo ordinary way ; 
■t> that hi-iT, tiKi, ihtt acccK'niling iiitluvncv of contact with furei^ bodiea 
Bakes ilwlf ft'lt. Similarly, niuvi-nu-iit of fhcil blo<Ml hnaloDii clodmg, ritice 
il iscrraHK the amount of contact with foreign bodioL So aleo iho addition 

■ wf MoagT (ilatinuni «r of powdered charcoal, or of other inert powderv, to 
lardilf riulline liloml, will by inflncnoe of ftiirfaco. basleu dotting. Con> 
vmtfV, bloiwl brought iut'> d^nlad with pure oil docs not clot to rapidly ns 

la coiiiact Mill) gliiw or metal; n»d blood will continue to tluw for a 
_ time without clotting throiigb n lube »ineared innide with oil than 
ihlOTgb a tube not to nmenrcd. The inlliienoc of the oil in Buch cnaee is a 
|itiy«irml not a chemical one ; any pure neutral inert oil will do. Ae far as 
wa ktiuw thp(« inlluencea afleet "oly the rapidity uith which the clutling 
take* place— that if, the rapidity with which the fibrin niakee its appear- 
ancv, iMit the amount of clot, not tlie (junnlily nf fibrin formed, though 
when clotting it very much retarded by cold changes may ensue whereby 
tbe aoMNint of dotting which eventually takes phicc is indirectly aflected. 

Iftn etpoaure l<> air eserls apparently little influence on Ihe process of 
deuisf. Blood mllecled direct from n hloudveairl over mercury so as 
wboUy to exclude the air, clots, in a general way, as rewlily a« blood freely 
fX|NMd to thv air. It b only when blood ii> much laden with carbonic acio. 
lb* prewDce of which it antagonistic to clotting, that excluHon of air, by 
UlMlefio|t the escape of ll»e exetw of carbonic ncid, delays clotting. 

TImm ncta icaui us that 6brin ihiee not, an was once thixight, make its 
■PpMrinn» In alitd bloixl because ihe blood when shed oeosea tu share i» the 
iiimiineHl of tbc circulation, or because the bl(K>l is cooled on leaving the 
warn bodr.or because the blood is then nioro freely cs]Msrd to the air; they 




further ftigEHl |fa« view tliiil ihv Hbrinbtlie result of some cbemical _ 

the cxHiviMvioa ioto libriii of mimL'thiiitc tvliiob U not tibriii, the cbuige like 
Otli«r clicmica] cbangei Iwiiig nicwt uclivt; at iiii ofilimum tempenitlire, and 
like fo ninnv otber chcfnicnl clinii^ro, Iwing nsHniinl by ihi' iiiHu€Deea cocflrtcd 
by the [imwiiM of iiwrt bwiiw. 

And nc have direct I'xpcrinivntul evidence thnl pliutitm does contain aa 
SQle4.-eddiit nt' tibrin whidi, by rlit'niicnl change, it convvrlMl itito fibriu. fl 

§ 19. If bloud bo rvcoivcd ditvL't rrom ibe blood vrsM-ls into oue-ttiird il^ 
bulk of a aaturaced soltilion of toniv tit'iiCrnl iHilt Fiich m iiiae>"'iuni :iu]|>bnti.>. 
and the two gently but thoniiighly niised. clotting, <ii|iuriiUlv iil u mixk-r- 
iiU^ly low tcni]>er«tiire, will be deferred for ii very long limo. tf tbs tnixtuxd 
lie nllowed to stand, the corpuHi-lea will bink, iind ii uoWlov nlanni will 1^1 
obtained siinitar t«the {ilaaina ^tiined froni horse':' blood by mid, cxcvpl thnt 
it contains an excess of ibc neutral salt. The presence of thv neutral «alt 
luu actod in the same direction as cold ; it bus prevented the occurrence of 
clotting. It liaa noidestroyed the fibrin: for if some of the plasmu Iw diluted 
with from liv« to ten timea its bulk of water, it will clot speedily in quite a 
normal fashiou. with the production of ijuite oonua) librin. h 

Tlic separation n( the fluiJ pluma from the corpuicle* and from other bodE^I 
heavier lann th<> pluimn U much fiurilitiilpd by thr u»c of the cpnlrifagnl machine. 
Thia cuiisintfl nLionUnlly afu lirelcm wheel with suvernl ipvkes. placed in a hori- 
ziiQlal podUou and tiiude to rdvulvewltli great velocity ilWx* reToIuttons per 
minute for iottaDca) around it« axis. Tubc« of metal or very Strang gloM arc 
Hut|>eiided at the ends of tlie >|iokni by carefully at^ustod joint*. Aji the wheel 
roinies with increaung relciiiity, eoi-li tube gradually Maumoi a horitoolal poal- 
licm. bothim outward, without iipilllng any of Its conienla. Ai the rairfd TOtatioD 
cofitiuuH the corpiixulcti and heavier particles are driven to the bo4tofnof th« 
lube, and il n very rapid movooiont be continued for a long time will form a com- 
pact cuke nl the bottom of tlic tube. When the rointion in stopped the lub«a 
gradually return li> llieir upright poaltioo njrnin wilhnut anything beins npilt. 


the cl«ar pluania in cocb tube can then be decanted oil'. 

If some of the colorleaa tranaparcni ptasmn, obtained either by ibe action 
of noulrul sall« from any blood, or by llie help of cold flrooi horee'e blood, he 
treattnl niib some solid ntiiirul sail, siicb an Imodium chloride, to saturation, a 
white ilaky, soruewhai eiiL'ky pii?cipiiate will make itn ap|>earaiice:. If thia 
precipitate be removed, the fluid no longer pcaaewct the p(iwi:!r of clotting 
(or very oliKbtly so), even tbougb the neutral salt pr«wciit bi^ removed b^ 
ilinlyaU, nr iu influence leeaeueil by dilution. Wilh the removal of tlte suH| 
niaiice prcnpiialed, the plaima ban lo!<t itsi power nf clotting. ^^ 

If the ]rreci])itate itwif, afl<T beiiij; washed with a mturati'd Molution of 
the neutnd salt i,in whlc-li it i.i insoluble) to a* tn get rid of at! wrum and 
other eonslituenld of the pbiyma. be Ireut^tl with n smnll ijuiintity of waMr, 
it readily dtMolvea,' and thi; foliitinn riipidly filtered givc« a cicnr, colorleas 
liltraiv, whidi i« at ftr*t jM-rfrclly tinid. i^on, however, the flinditv givea 
way to vi«'idily, and lhi» in turn In n jelly condition, and linally thcjclly 
Ghriukv into u dot fltMttn^ in ii dcnr Huid ; in other wonls, the filtrate clot* 
like plasma. ThiiN tbon- is iirtvcnl in cooled plasma, and in pliismn kept 
JVoia clotting by the pn^-noe of neutral salu. it somethiiiif pn^ci pi table by 
mtnntion with uculnd ^nlUi — a Foni<'ihing which, aiuee il is soluble in very 
dilute Mlini^soliuinns. cannot he tibrin itself, but which in solution speediljr 

K'ves Hm to thti appearance of tibrin. To this subnauc« iia discovered 
enb, gave the name of plaimiue. ^ 

> Tbt iiibManM luctr ti Dot tolnUe in eliUIked wtivi, i>ut ■ umiitliy ol thv nnilml mII* alinui 
(Man to tbv ivMirliaw, •ii'l <Hi» Ilia a-bllUon ot w>M rlnuatfy gtm rtt lo dilute lalltM aduilLin, 
fa oalcli Uw •utaiauw ■• rniOll]' wlubli:. 




TIm MihaUincc Ihii* nrvciptlmlcil U not how«rer n Kn^h; )>lh1v. bul n mix- 
tan of M \auA tito botliea. Ifsudium clilondo b« i-xn'tulU- luliW lu pljuma 
h> mtt •XMOl of kImuI n |i«r cvni. n wliiie fliiky vi*ci<l pmciplntv ix ilirunra 
Aoma Xfrx much like iiliuniini:. If alU-r ihc rcmo\-»I ol'thv Rm |(r«(-i(iiutl« 
•tijiuai chloridr, Miil <'«(ir>:inlly if iiiAgtmium sulphsto bo mlilrt). a 
' precipitate u tlirowii duwii. Iu<« viitckl nnd inure ffruiiil&r tliAii the 

Tha aMond pnvipiUiii; whcii <'xam!n<?l i« found ut bd identical vilh Uto 
fmrmgiahmiut. cMigiilnliiig at 7'}^ C. which we have nircadj aeen to Im » 

«fMMUl4Mllt uf WrilRI. 

Tba Ani pret-i|>iuil« ia also a proteid balongioi; to lli? (clobullQ ([roup, but 

ftn lV<>iii |>;vrit;;lubuliR, not otilr in beinj: rnure r«n'lil>' prccipttutud by 
waUrn chloride, and in b<-in^ wh«n procipilaied inure vineid, but ubto in 
(4iMr rspww. and eepeoiallr in being coagulated at a far lowor tvinpornturv 
tkao |MtnicI»bia, vix., at S(i° C, Now, nhile i^ulatvd pamglubia canuol by 
may maaM known to ua be converted into 6brin. and aa ti« procnoc in the 
MMxUted plawnine doea not aeem to be OMeaiiu) to the formation of 6brio 
oat of itlaamiDe, tbe preaenoe iu plaamine of ih« IhhI y oiiapiUting at 56' C, 
4o« aaaoi oiMutial to the otKireraiMi of pla^tmine into fibrin, and we have 
fMin S>r thinkinir that it 'n tUeU ctjnverlc<), in pitrt nt least, into fibrin. 
Hmc* it ha* rvceiveil the name of filiriHw/en. 

d so. The n-atritLH for thU v'mv! nri; an folloWM: 

Bfaidai blood wbioh clot* naturalljr when ahad. thert- are Mrtnin fluids in 
iba bsdjr which do not elot nniunilly, citber io the b.idr or whuti abed, but 
which t>r cvriiiin artifir'iitl mean* may b« mado to clot, and in cloltinj^ tu 
jriaJd ^nttr normal fibrin. 

Thoe tb« »0'i-all(Nl ecroin fluid lakrii Mroc hours after death' f^om the 
perifanlial, pleural, or peritoneal t-avities. the ituid found in the volarved 
tareaaakc uf the leatis, known ad bylro^-ele lluid. and iitb<-r »imiliir fluids, 
«91 is the majority of oues, wlteii ubiaineil free I'roui blood or othi-r admix- 
lana, rwmain fluiil almost iudeRoitoly, shuwinjf no diipiwiiiuu whnlerer to 
doc' Yet, in muK t-adce at uU events. tli«M: Ituidd, when a little blood, or a 

St of blood olot, or a little terura h addul lo iliem. will clot rapidly and 
Ir.' g:ivin); riae to nu uoroiMakable clul of nomal fibrin. ditTiiring only 
fritn tk<> clot of blowl in that, wlieu ■crum ia usad, it i« colorless, being fnt 
from rtti corriuidot. 

Nnw blood (or blood clot, or iwrum> contains manv thinga, to any one of 
vUch the clouiog power ihuvuvcn mixhl beatlribiiUM). But it h fuiind that 
ia BMuy ouea dotting may Ix.- induced in the Buidt of which we are speak- 
iac hj the mttf addition, and llial i-ven in <:xciixlingly small iguantity, of a 
PiMlUK!* which (»n bo cxlracl^-d from l>I'x>d, or from serum, or from blu:)d 
doCurerMi fnim waithed librin, or iitiL-cl fryjm olhor aourcea, a subataooe 
whoM rxMct nalurr i; unn-rlniii, it Ik-Ir); doubtful whecber It is a protaid at 
alt. aoil whoM' acii«ii i* jMrouliar. 

If eenim, or wh!pj>nl blood or a brokcn'Up olot be mixed with a large 

riBlity of alcohol and altowHt to ataad some days, the prvileids preseai are 
tine M changed by the alct^Mt) as to become insoluble in water. Hence 
if tbe orpiooa precijpitote caused by the nlrobol, after long aiandinjc. be sepa* 
rated hr filtraiion from tbe alonbol, dried at a low temperature, ugt excead* 
la( 40 C, and exlmcte<l with dutilled water, the aiiueous extras contAiitt 
tittle protetd matter, indeed very little organic matter at all. NeTSi^* 

1 ir H b« tnoavwl InawluMi tlUi iIhiIi u gaiisrally cM> rMdltr aad dralv. ftilai ■ oolarlcM 
CM OMiMtBe of sum •iM >(dta owiouIm. 

• la BM* (faiDiHai. iM«*<t>. • ■■•MUaaint oMfoWiiB, s ft. '»llr iltsiii, tat iii «xotf€iaiwl 
•■■• maMf*. mtj Im ulaanwL 

• tM«S»w*aaM^eMsid*»aaaruiib«tbrtiid*<v4. 




tbelcae, eveii 8 aninl! tuinntity of lliis afjiiPfnis extract milled aliDe to oertitto 
sneciiQctiBiirby<)r>H-elc tluiJ or other of ihe HnkU H[>i>ke(i of above, will brio;; 
Kuotit a Hi^edy dottiug. The eaiiie a>iueoi» extract has alau a remark a b£ 
l^l^l;cl in biuteDiun; the dolung at' Hiiids which. I.hougb they nill eveotually 
cloL, do so ver^ slowly. ThiM ptaNiiia may, l>y the careful addiiJoD »f n cer- 
tain quBiittty uf neutral «alt hdiI water, be reduce*) ti> mich a condition tliat 
it i:l»i* Terv'iilowly indeeil, taking perhapM day* in cDnipleli; the proccM. Tlte 
addition 111 a Anall ijuaiitity of thi: »i|iie<iiiK estrart wc are iJeacribing 
huwi.-vi-r. bring abiiut a i-Inlliii); which w at i>nc« lapiil and complete 

The active rubotancc, uhaltrvrr it he, in thii< a<)ucons «xlmct exists 
rmatl quantity only, anci iiR cintiing virtues are at odcc and forever 
when the wintion i« boiled. Further, there is no reason to think thai 
active 8ul)s(iince actually enters into the formation of the tibrin to whieh it 
glTM rise. It appears to belong to a clasi of bodies playing ad imiw.rlnnt 
pitrt in pb^'siologicn I proc^iMS, and called fermenU.ot which wo shall have 
more to say hcrcaficr. We may, therefore, ^peak of it as xhv ^rin ferment, 
tbe DBiue ^iven l» it by its discoverer, Alexander Schmidt. 

This Kbriii fcniit-nt is prec«Dt id and tuny beeilraclcd from dolled or 
whipped blood, itnd from both tbe dot' and the serum of dolled blood ; and 
bince in moel, if not all. cases where blond or blood clot or serum produces 
clottiuK in hydrocele or peiicardial Huid, an exactly similar dolhinv may be 
induced by the mere additiou of fibrin ferment, we seem justifieu in eon- 
duding that the doitiiiK virtues uf the former are due to tbe ferment whic 
ibey contain. 

>i«w, when fibrinogen b precipitated from planma, as above devcribttl, L ^ 
sodium chloride, redissolvetl, aud renrrcipitated, more than onoc, it may be 
obtained in wlution, by h«lp uf a iJilute neulnil mlinv solulion, in an *E^ 
proximnielv ptirv condition, nt all evciiM free from oilier protCKU. Such d 
solution will not dot ■poiilHiieoiisly; it may remain fluid indclinitely ; an^^ 
yet on the addition of a little Hbrin fcnueni it wilt clot readily and firmly, 
yiddinc quite normal fibrin. 

This body libriiiogcn is also present and maybe separated out ftom ti 
spccimcDB of hydrocele, pcrieaniinl, and otlier fluids which clot on tli 
addition of fibrin ferment, and when the fibrinogen has been wholly retuovi 
from these fluids they lefuse to clot on ibe addition of Abrin fttmeut. 

raist;h'bulin,on ibe other hand, whether pieparcd from ploamine by scpa- 
ration of ibe fibrinogen, or from aeruni. or from other fluids in whidi it i j 
found, cannot be converted by flbrio ferment, or indeed by any other mrat^l 
into tibiin. .\nd fibrinogen i.wlaled. as dMcrihed above, or serous tlutda 
which I'oiitaiu fibrinogen, nin he made, by mcanc uf fibrin ferment, to yi«l<l 
quite uiirnml ^hrin in ihe <um|i1eie abwnce of paraglobulin. A solution of 
paraglobulin obtained from »erum or blood dot will, it in Inie, clot pcricar- 
car<luU or hydnicdc tltildii containing fibrinogen, or indeed a KiluliDa of 
fibrinogen, but thi« U apiiarenlly due to tbe fact ihal the imirnglobiilin ban 
in ihm cucn fonie fibrin fcrmrnt mixed with it ; it is aUo puiixible tbut, 
under rcrlain C4>ndiiioiis, the pr«»enc« of paniglobulin mny he tiivorable I^h 
the action of the lermenU H 

When the so caDtd pln^mine is preelpilatcd. a» directed in S 19, fibrin fer- 
ment is carried down wiib ihe fibrinogen and paraglobulin, and when tbe 
pliismine is iC'diHolvcd ihe ficiment i» prrsent in the solniinn and ready 
act on the fibrinogen. Hence ihe redissolvcd plasmine dole spoDtaneou»lj 
When flbriuogen ts isolated from plasma by repealed precipitation and aolu 





■ A wtKrlUI wlaUon «f nbtln fcRirtiil mty l* rMdllr |>ni*n<l !■)' tUa\it 
bliH'd I'lol vtll ■ lU(*ruDI. »tiiil<in or •■xlluni chloriilc. 

xmrUna • wulicd 




tfaa, ibfl CtmuMl H WMhed nway from it, vnil [he nura fcnnvnC-rrvi' (ibriii- 
mtm, ultinuiti'lr obtaiiHy), i\i>ts» not dot «ponlaD<i»ii«ly. 

iki fmr it mvhio cl«iir thai thciv doos oxMt ■ proteld hndy, Rhnnoga}, which 
mmj by the m-tJon of fibrin ferment hv <)!rrclly, u-ithuiit tht intcrvi-iition i>f 
NtMT proleidA. <:i>avi.'ttr(l iolo ibc ]*>« m>lubic fibrio. Our kiiowlnlge <>j' lliv 
nnnHllilifin of proteid Ixxlics is too iin|>crfoct to eiiablo us lu iiiako unv v«ry 
ddbilta M*leiu«nt ■» to the cxiict nnUira of Iho chnn^ thus dTcctcd ; but we 
mj MT ibie mucli. Kibrinof;cn anil fibrin hnve iibinit iho trntav (.'li'iucntary 
■OBpcaitloD, fibriu ouuUiniiiK fl triHe inoro nilro);eii. When fibrinogen ib 
eMmrtrd into 6brin by nwans of Kbrin fermcDl, the weight of the Hhrin 
ptvdocBd k aJwayn l«i>s> than that of ibe Rbrinogen which ia consumixl. and 
tbvre y bIwos jiroductii at the aanie time n t'ertaiu quHutitr of nnothrr pro- 
Uid. iMloogiug tu the );lubu1iu family. There are reaauna, liuwever, why we 
OkOM* ipaak of the furmcul. un tjttitliH^ up 6brinu^D into librin and a glo- 
bolin : it avcmi moro fmihHbl« that tike ferment cmverU the librinogen lirst 
into m liodv whi<^ti «i- luivht call toluhU ^rin, aiul then turua this body iutn 
rentable lihriii ; l>iit furihvr iH(|uine« un lite subject are needed. 

It nay b« uihU-fl ihiil among thi; cnnditiom ncM«iary fur the due action 
of Sbrin rr-rawDt on fibrimigCD, the pruwooe of a certain quantity uf sonn 
Hairal talt Kvns to b« one. In the total abaence of all neutral aalin the 
ftmmX oinnot convert th« fibriDogvn into fibrin. There arc itume reuaouB 
ako Jbr thinking that the pn-aciice of a lime .talt, «uch a« calcium aulphale, 
tlMOgli it nay be in minijie i^uMntity oidr, U <-]wiiiiitl. 

ffi. We may convlude. Ihcu, that the plnHnin uf hhxMl when Hhed, or, at 
•U «f«Bla,a(KiD after it h»» l>e<.-» *liL'd, contnin* librini<)|:en ; and it al«o Mcenia 
pn>lwbl« that the clotting cmiiiii about Ifcauio ihf Hlirinoj^ is mnvurietl 
Btio tMa by the action r<f librin fvrniritt. ; but wo nrcilill far fmni a <Ivfiuit<> 
aanrar to the (pMsliMi, why blood remains fluid in ibe body and yet clut« 
wbra »hod7 

We have already uid that blood, or blood ploama, brought up to a tem- 
pefBlttK of 56'^ C » «oon as |H«iiibIe sAer tla removal from the liviDB blood- 
•MMk, givM a proicid pr«;ipiiate and 1u«m» it« imwer i>f clotttnu. This may 
W taken to *how that blood, m it circnlaifo in the Uvinfi bloudvewela, con- 
talaa flbriaoiNn a» nich, ami that nhm the hlui»l ■• heated tu 56° C. which 
ia tbe cimguTating point of libriHcrgcu, the fibrinogen proteul ia cuaKulateil 
aul preripitnltil, and conwK|ueully no librin can lie formed. 

FurtlMT, kIiiIi- riotlod blood uiuluul.U-dly i.i>niBini> un abundance of fibrin 
fcnerot, ii» fi*rn>ciil. or a minimal c|ii]tniiLy only, i» preeent in blood lu jl 
Iravr* llu> blood v(tPi*l>. If ih*- blond be rcceivt'd directly from the blood- 
weak iutii eloihol. tlir niiuentin extract pr\-|<an-d, ai> directed above, cou- 
taioe Bii frriiicnt, or mrr\'ty a truce. Apparently ihv ferment maktv itM 
appearani-r io the blood ae llie result of eliangm taking place in the blood 
aflcT it hat licen ahed, 

We iiii):hL from ihia 1>e inclini-d to (-oneUide that blood cloU wlM-n lilied. 
bat iMit betori!, heeaoHe, fibrinogen being nlwaya prreeut, the chethlinii bringn 
abuut ctumgea ithieh prMluce fibrin fernieiit, not previonely csi«ling, and 
thii acting on the (ibriiKigen gives riae to librin. Itut we meet with lliv fol 
kiwinf difBirulty : A very couHidt-rablo i)uaniily of very active ferment may 
be injected into the b I oiid- current of a living animal without necrvvarily pro- 
Jad^ any cl'>tiing at all. Obvi<Hifrly either hlood within the blixidvemcls 
da« twM contain liljrinot;en ati such, and the librioogeo detected by healing 
tko bloud tu >'><{' ('. i* the ivsult of change* which have already eonted Iwfore 
thai lerap^mtun- i« nacheil : or in the living i-irnilaiiou there are agcocica 
■Cwwk «hioh provrni any ferment which m.iy Im tuLroduccil into the cireu- 
Inlioa from pruduciog iu usual efl^la mi tibrmo^n ; or there are agvnctva 



at work which dntro^, or do away willi the fibrin, little hy little, aa Jt b 

$SS. Antl inilecti when wo rvfl«ct bnw citi)])I«x btoixl ■», and th« toauj 
and great chniigra U is simocptiblc. wr shnll not wonder tlutl ihe quettion 
nre mittiiiK cnnnot be answorcd off hand. 


The coriiusclftt with which liWd ic crowded uro living stnieturei^ 
coniMKiiictitly nro continually ticttng upon nnd being aeUd upon by the 
pliuiDB, The rod corpuscles il is tniB are, m n-e AmU h«. pcctilinr bodici, 
with « rc«tnct«d life and a very speeialized work, and pomblv their influ- 
cuc« on the plasma ii> not very gn>at ; but we have reason to think thai ibe 
relations boLwcen ihe while corpuscles and the plasma are close and im- 

Then af>ain the blood is not only acting upon and being acted upon by 
iho several ttsFues oa it flows tbrotigh tlie various oamllaries, but along tba 
whole of its course, tbruugli the heart. ar(«riefl, cnirillaries, and reins, is acl- 
io^; upon and beiog acted upou by the vascular walls, which like the rest of 
(he body are alJve, and being nlive are continually undfirguin;i: ami promot- 
ing change. 

That relution« of Aorae kind, haviug a direct iufluonoeon ihecloUingof 
blood, do exi»t between the bl»od and ilin vaMCiilur walla is rthown by the 
following facts: 

AiitT d«aih, when all motion of the bloot) haji ocaM*!, tlie blood r«(uaiat 
for a long time fluid. Il is not until some time nfUrwnrd, at an epoch 
when post-Diortom ehmigej* in tbc IjIoikI aiiil in the bloodveMvl* bas-e hod 
time to develop thcniscrvi's, ihat clotting Iwgins. Thus Rome houiv after 
death tbe blood i» the great veins may he found i>lill pcrfecllv fluid. Y(t 
such bloorl has not lost its power of dotting; it slill cIoU wlirn removed 
from the body, and clots too when received over niereiiry without exposure 
to air. showiug that, though the blood, being highly venous, b rich in car- 
bonic acid and contains little ur uo oxygen, iio fluidity is not due bo any 
execm of carbnuic acid or abni^nee of oxygen, Kventuatly ii does dot even 
within tbe ve-tii^lH. but |ierha|<!i never so firmly and completely at wl»eu 
ahed. Il clots tSriil in Uie larger ve>Mel-t, but reraainsflui<l in the amaller ves- 
sels for o very loug time, for ninny houn lu fact, «noc in thvse theaauie bulk 
of blood ia expiKted to the iulluence nf, and reciprocally exerta an influenty 
on, a larger surface of the viucutar walU ilmn in the larger venela. And 
If il be urged that the re.iiiU i.i here dui? In iiillui^nceo exerted br tbc bodi 
at large, by the tiasuM us well ai> by the viweular wallit, thin objection ~* 
not bold good agaiDHl the fiillon'iag exiicriinont. 

If tbe jugular vein of a lurg<! aDiinal, such a« an ox or horse, Iw carefil 
ligalured wneii full of hlooil, and thu ligatun-d portion cxdwil, the blj 
iu many caiHSt remaimt perfectly fluid, along thr greater part of the len^ 
of the piece, for twenty-four or oven forly-dght liours. The piece so liga- 
tured mav be eu«pcndcd in a framework and opened at the top so as lo imi- 
tate a living t(»t-tube, and yet the blood will ol\cn remain lone fluid, though 
a portion amoved at any time into a glass or other ve&#el will clot in a few 
mmutes. If tiro such living teet-uibcs be prepared, the blood may be poured 
from one to the other without clotting takin;; place. 

A simitar relation of the fluid to its coniainin;; living wall is seeil io tbe 
case of those serou* fluids which clot spontaneously. If, oa soon after death 
as tbe body i* coid and the fat is solidified, the t>ericardium be carefully re- 
moved fVotn asbeep by an incision round the base of the heart, (be pericardial 
fluid (which, as we ha>-e already seen, during life, and some little time after 
death, posacBsea the power of dotting^ may be kept in the pericardial bag a* 



te > livioft Clip for Riauy boiin wiiiioul ilottiiif;, utA yet a iihaJI porti»u re- 
Bomil mtli n |>i]>ette rlols st once. 

Tkti rvlKiioti brinu-ii tli« IiIimmI ami the vasculur wnll may be dialiirheil 
or ovcniiMf-n : cluilitii; nmy tiike place or may be induced niiliiii itie livluj; 
Uoodtv**!. WIm'ii iliu liDiriK uiviiitiiuD« » injured, n« irkeit nil arury or 
win h ihsrply lii;iil<in-il, >jr wlivu it w diceaKd. tu fur iDHtaiicc in Biieurwro, 
• dot i* *\'l lo bv li<riiiiH] at ibo injured ur diM-tiH-tl sixil ; kikI in ccruin 
■oririd eoodilioiM of the body eUitf arr r»rRi<s) in rani>uii vaiwular UitcU. 
AlnmeB of iBntion, «hioh in vhtil I>Iimh1 ii» w Imvc »«en, i« unfuvorahic to 
dattiiag, 1* apt "ilhtn tlH< bo>ly tu knd h> plotting. Thiu, uhen iiti nrlcry 
b HpUnrrd, tlic blwid in lli« tnct of llie arlvry on the curdini: nidi; of the 
S|Uan>, bolwcf'n tbt> iigaluir aul (hr hninoli Wt givvn citT by lh« tirlcry, 
amtkof' to iban in tbv circulation, rvmaiuv ingticinlcm or iKarly ao, aiid 
•Img thb tract a clot (nrta%, linni.-*t nvxt ti> lli« ligiiiure nod eoding atmr 
■ban iIm branch i» given off: thii> twrhap* may hv cxplitincd by the fact 
that tba walls of the irsrt Kiiflcr in rlicir nutrition by Ihr rtagnaiion of tJi« 
blood. Ktwl itial cuQMqiHiilly the Dornial relutioD between thcoi and the cod- 
Uiaad t>['-»l is dialurmd. 

Tbat th« blood within tlie liring hloodrcaacb, though not actually dolling 
nadar DoraMtl circuniKtanix.-^. uiuy cwily be made to o(ot. Dint the blood is, 
:. av t« malt, always on the point of cloitiDK. u shown by llie fact 
fonign body, nieli as a oeedle thrust into the interior ufa bioodrnael 
fvad drawn lbrou;!h amt li-A iu a Idoodvcaial. is apt to becoma cot- 
«ilb fibrin. .Sotoo influence exer(e>I by tli« needle or thread, whatever 
ba the cfaiinu:tor of lliat iofluence, i» sulHcienl to deteriuine a cloiliu);, 
Mbcfwite. would licit have taken plaee. 

«a»c iiutakiliir of the hliHxl, as regarda clotliu^', is strikinjciy shown, 
caM of Iho ra1il)it nt least, br the rtsiilt of injttcline into tlic blooil- 
a snuill ijuantity of a solution of a peculiar proteid, prOMired from 
•truotun* such us the tbymiis body. Masiive clotting or th« blood 
iMt all the blmxlveAsels. snmll and large. takc« place with great 
y, iMdinjc to the »iddcn death of the animal. In cotilnut to this 
may br nwnti'Mied (he mull of iiijectin); inio the bloodvessels of a dotf 
qitaulitr "f u tohitioD of a body called albtimote, of which we shall 
h^wUrr linve lo trnit ns a product of ihe dif^Uoo of proteid sufaMancca. 
aatent nf (>M jcTammc |ier kilo of body weight. So far fmio priKluc- 
tiog, Ihe injcrlfd nititinione has such an e^t on the blood thai for 
houn KJVr ihi- iiiictioD shed blood will refuse to cl»l of itself and 
D quilfi fluid, Uiou)(h it can bo made to clot by sjieciul Ireatnicnl. 
SS. All thi- forevoing fiwta tend to ohon' that the blood as it is flowing 
the htwlihy^loodvcanla (■, a* far aa •■lotting is oonccroed, in a state 
wguililiriutu, which mar nt any inonK'nt bn uirvt ; even within 
lv«ael», iiu'l which is upnet directly the blood i* nWil. with clotiing 
ramiL Our pmteiit knuwl<><Ige does not itenuit ii* to make an authori- 
alatemeol n» lo the vxttvl naluni of this etjuilibriuni. There are rea- 
however, for thinking ihnl the white oorpuwU'w play lui ini{ioritinl 
ki the tnattrr. Wlimtver cJuiiiDg occurs natumlly, whitv corpuscles 
I : and ihiu is true not only of blood but also of such spocimena 
dial or other serous lluids as clot niilurally. Wlten horse's blood 
kept fluid by luHnf; relaineHl within the jugular rein, lU menliomd a llttla 
V bock, and the vein is hung upright, the oonMiscka, both r«d and while, 
., leaving an u|-|K-r laver nf plik^nia almost rrae from oorpuacles. Thia 
ar layer will l>e foun<l to hare lost largely its power of clotting spon- 
■ly, though iho |iotier Ii at once refined if the white c>r|itiscla from 
layrr* beneath be relumed to lU And many other argunKnts, which 

■bike I 

MM If If. I 
UW Uyrn 1 



all pcimrin^ lo the oaine con- 
iinpuriai)t juirl iti lUe promss of 

u'e cannot enter upon here, mny he ndduced all 
rluHiim, thai the wiiiie enrpuBcles play an _ ^ 

clotting. Jliit it uoiili] lead ua tix> tar into L-i>ntravertaaI matten lo atleiiipt 
to define what that jmrt ia, or to explain the exact nature of the equilibrium 
of wbidt vc have anakeu, or to diacuBS such <|uciitiiMi8 aa : Whether ib« ordi- 
nary whit« ei^r[iu*u[ea, or corpusolw of a s|»et:ial kind are cunccnicd in iW 
malterf Whether th« oorpiiscles, when cloltine taka place, e.^., fibrin- 
ogon or fi^rmeiit or both oraomeihiiiK else, or whether the onq>ilwIcii »im- 
ply in womw way or other Hfsiitl in the tmnnformnlii'in of .iOmo prwiou*tj 
«jci»tiD]{ w>ii»litn«DU of ihc plaiMDa? Whethi^r the influenoo exerted by tbc 
condition of (be va»cii]nr wall it exerted dirwctly on the plunma or indi- 
rectly on the corpuscle*? Wlicihitr. u •ome htive ihoughr. iliv pcailiar 
bodie*. of which w(! shall presently upcsk under tJic namo nf blood plaleJete 
or pia^uet, hare any share in the matter, and if tra what? Th<«« que^iionB 
ar« too involved and the discuwinu of thcni too long to ho entered upon hero. 
What we do know thnt in blood soon aftor it has been elied. the body 
which we havo called fibrinogen \t present a» also the body which we have 
called fibrin ferment, that the lutter actlnj; on the forni>!r will produce 
fibrin, and that the appearance of Hhrin is undoubtedly the csu<e of what 
is called clotting. Wfl Beem ju^litied in coticlitding that the clotting of abed 
blood ifl due to the ConrerHion by ferment of tibrinogeii into fibrin. The 
furl her inlereiice that dotting within the bmly is the same thing as clotting 
outside the body, and stmiUmy due to the trans for ion tion of fihrinoji^u by 
ferment into librin, though protMble, la not proveil. We do not yet know thiB 
exact nature and cundition of the blood within the livio); bloodve«itla. hd^B 
until we kudw that no cimnot nit ii»ftiut only explain wliy htuod in the living 
bloodveMelgi is iifiiallv lliiid hut can at linuw clot. 

The Coi{i'i,'H(;i.iw or thi: B1.0011. 
Tlie Rfil CorpMdf*. 

§ 34. Tlie redneM of blood is due exclusively to the red corpuaclea. 
plasma a* K«en in thin layers within the living bloodvnaeU appenn rolor)<4«, 
Bsdoe* a)M)a thin layerof serum : but a thick layer of serum (and probsbty 
of plattnm) Iibh a faint yellowish tinge due, as vre have said, to the prcMnoo 
of a small ipiantity of a sfteml pioiuMit. 

The OorpusclM appear under the niicroM!0[H- a* fairly horaogVQKHi*. im* 
perfectly traiwluccnt biconcave dLir* with a diameter of 7 to A yi and a thick- 
neaa of I to 2 />. Bdng dine* they arc circulnr in outline when seen on the 
flat, but rodxhajmc! when »neii in prolilf tus thny arc liirntng over. [Fig. 'p. J 
Bdng biconcAvc, with n thicker roiindM rim surrounding ■ thinner centre. 
the rays of li^ht in piu«iing thn)ugli ilicm, when they are examioexl by 
transmitted It^ht, arr^ more n^fracled at the nm than in the centre. The 
etiect of thii> i>> that, when viewed at what may ho considered ihe proper 
focUH, the centre of a coqiusclc np|>cnra clear, while a eliijht opacity mark* 
out indinlinclly the inner mnrgiti uf the thicker rim, whereas, when ilie foc-us 
is shiAe<I either up or down, the centre becomes dark and the rest of the 
corpuscle clear. Any body of the same shape, aud composed of substanoe 
of the same refractive power, would produce the same optical eAeolS. Other- 
wtw the corpuscle appears homogeneous, without distinction of part* and 
without a nucleus. A single corpuj«cIe seen by iwelf has a very faint cohir,^ 
looking yellow rather than red, but when sevcml corpuscles lie one upon tk 
top of t^e other die miuu is disiinelJy red. 



Tb« f*d corpuscle i» i-lftstic, in the kdik ibat it tstny be deforitied lij 
ptamni or tnctloo, bul wlieo Uie pnasun; ur tni(-ii<>n in removed rogaiai iu 
pnviiMn fbnn. lt» shape b also touch inHiiviii-t'd bv tbi; phyncal condilioM 




fh). 9l— NcsikS IhJinli ^ ma u> Hit VTini) «tiiiK. lUniiiiIDO'l atoHit IMDdlUBtUnkI 

I I Itmfh Urt IMI I IjlUKlUi, r.r; rvnliviiinwlcion (belt odc« UMl rttwol tli t*alU*l 

'•, mA iMiBwtlti ■n«niid in roulawii; r.r.crmUc iwl cvrinMiln: p, ■ HMty B'<»i>l'>r I*!" *•"• 
tm^t . 9, • nanvlf (M»al*r p*te <«ir|iaKlP. U-db liarn txu uf Ihitw dliUnol ncinln. nod *cfw 
wAnaoUit cbaii^M •>( (hatB at lira iDM»iri of •it'wfTiilkia ^ ill p ■ tiuclcoa tim turn rlilbUt. 
r>> d-lliat.i Kiti cuHi^-nuu. I.iin-. !<t!i»LY u<»'»i.unn> Drm Iumia (At wmsnderM 
Witi ^w*r at Iha nucrnBM)!*. i ] 


irxi I. 


«f tlMpla«Bm,Mrum.wrllui(l in which firthi- limo being it i*. If tbe {ilnsma 

«r Ptmtn be diliihs] with water, the ilisc. ulMi>rliin^ wiiler, fniKlln u|i inl» ii 

*pb«n> [V\f. *}]. becoming a disc n|;tiiii on tbe rciDOTsi ol' the dilution. " 

iMMTUm be coocentraied, the disc, |>ivint; out 

nl«r. shrinks imgubrly and aBsunrcs vaH'xi* 

(^•rcM; <)D(! of thcM fornu is Ibsl of a nuMilx-r 

of Uodttd |>MlubeTauu»i pruimiin;; ail uvcr 

iW Mirfiue uf tbe t;ijrf>UH:lv, wliifh is then said 

%m b* crvnKte; in n drop of blood (.-xamined 

HMler tlw niurosopt', vrenale mrpiiM^'les are 

«Aaa aeeo at ihi- nl^ie of the cover nlip where 

«<npmii(iD i» leadins li> ronocn I ration Df the 

p to awK, or, U it stuKifd tWn |H-r)in|M rather be 

called, (Wiiro. In hlooU jiut ahrd tlw ml cor- 

pnadM arv a|it In adhere to each iitli«r hr iheir 

^, .^^,,.^_ much more than tt> the giiMi or 

Hti ■' with which the blood ia in rontaci, and henoo arrange tbemMlTei 

ht roll* riiif tendency, howevar, to fiino n>lla very etxin diminishe* nfUr the 

blood bihiMl. 

8 8 

4 t 


o-f, >iici«ari*« eilbtt* "X water 
ii|>iu ■ ivl (orpiuota: / <tlR«i '4 
•uliitlna uf ibI(. cniiutcd : f, vllbft 
of Waiiie Kid.) 

Tbouli n •iii^lp ri>rj>iiwl4- '\* Hinn-nrhal trniuliiceDti a coniparalirely thin 
kjvr M klotid \» <>|iiu)iip ; tvjH-. for iiiKiance, cwtnoi be mtd tKrough eraD ft 


thin Uf ar of blood. 

WlwR a i)uantitr of whipiiud hlood (or blooil otborwiM depnved uf fihrio) 
ia frvMO ud ihawi-d Mvend limes ii ehangea eoJor, bocuming of a darker 




hiio, iiml if tbrn rotind lo l>c niiicb nioic tninKparrnt. *o i)iot ivfx- win roir 
b« irn»ily rvii't tlinxigh n niu<l«rnU-lv Ihin luycr. Il u then ^fmlcrn of u 
iahfhiood. The winiv rhniigo niuy lie cflrctoil by »hiiking ihp blood with 
ether, or by ad(lin<' n smnll <|iiRntily r>f bill- snll^ and iii other wnyi!. Vikki 
cxaminaliou of laky blood il is fouiii) tbnt the rr<t oorpuroles nre " brolcni 
np " or al li^asl altered, and ihtit the rcdnns nhk'h nrvviiituly was oonlinrd 
to tbem ia now diffused [broiii^h the Minini. Normal blood is opaque bveauat 
each corpiiEcle, while pcrniiUiiie tome mya of light (etiielly r«d) to oaa 
ihrougb, refteclB iiiaoy otbers. and the brigbliieM of the hue of Donutil blood 
» due lo ihis reHeclioii of liiihl Iroin the «iirfiiceB of the several corpusoltt. 
I^ky blood ifl traiisnareut because there are no longer inlact corpufo)«*to 
preseut Burfacn fur tlie rellec-iioo oT light, aod the darker hue of laky blood 
u (iinilarlr due to the uttsfuce of reflecliun from the several ci-irpusclee. 

Wbeo laky blooil is allowed to atand a sedinieut is tbrmed (and may be 
Mparated bv ibe centrifu);ul machiue) ivhich on examinaliou is found to 
conpist of dUcK, or frKftnieiiLt of iWws, of n colorlew auhstiince exhibiting 
under hi^h power* an olweun-ly Kpoiijiy or reticular structure^ These cotor- 
lof^, thin ili»('K MTii HuI-ivim; ofirii appear a» mere rings. The aubstancfl 
oonii><i»ing them »tiiiii:< wit)i vurioun rt*ag('iiti' and may tlius be made tDure 
evident. jfl 

1'hu rrd corpuscle, then, con»i»ta obviously of a ooUiriut frainontirk, wIhB 
which in nortnsl conditioiii; n red coloring matter is tURiciaU-d; but bjr 
various means the coloring matter may bv driven from the framework 
dissolved in the serum. 

The framework is spoken of se ^rtmo : it is n modified or dilTereutinl 
protoplasm, and upon chemical analyeia yields proteid suhftunceis some of 
them at least belonging to llic t/lohvlin group, and olher matters, amoog 
vbichis a peculiar complex fat called /nrMm, of which we shall have tospeatc 
In treating of nervoua tissue. In Ihe nuclt-ated led corpuscles of the lower 
vrrichraln this difl^utiated ulroma, though forniiufi; the chief part of the 
celMiriily aniuud the nucleus, is accompanied by a variable amount of undif- 
fenniinied protoj>laMii. but the latter in ihe miimmalian iv<l corixisele b 
either aWnl nllo^lher or n-diiced to a minimum. Whethi'r any part of 
this stroma is living, in the scnsi- of being ctijrmbleof carryineon a continual 
double chemical chang*.-, of i-onliuunlly buili^ng itself up as it breaks dowiH 
il a qiieflion too liitliaill to he <lii'ciin>ed hcnr. ■ 

The red coloring matter which in normal conditions i» associali-il with thi» 
Stroma may by nppTopriotc means be isolutcti. and, in iho case of ihv Mood 
of many auirosls, obtained in a crystalline form. It is called hirmaghbiti, 
and may by proper methods be split up into a pruleid belonging to the 
globulin croup, and into a colored pigment, coniaiuing iron, ctdle<l nirmatin, 
nsenioglobin la, therefore, a very complejc body. Il is found to have remarlt- 
mbl« relations to oxygen, and indeed, as we shall see, the red corpuscles by 
virtue of their hiemoglobin have a sjiecial work in respiration ; they cany 
oxygen from the lunga to the several tittuei*. We »faall therefore defer the 
furtliir study of birmoglobin until ne have lo deal mith respiration. 

Tbo red corpuscle, ihrn, con»i»t» of u ilinc of colorkrs stroma with which 
is acaociated in u prculinr way the complex colored btidy haimoglobin. 
Thongh the hamocti-bin. an in >ecn in laky l)lood, ts readily Mduble in serum 
(and tl is nUo soluble in pliisnm), in the intact normal blood it rcmaJus eou- 
fined to the corpuscle; obvitiuiily there is Home special connection between 
theatroroa and the btenioglobin; tl is not until the Tlromn is altered, we may 
perhaps say kille<l (ns by repeuted frci-zing nnd thawing), that il kwfl its liold 
on the hx'm<>>;l<>hiu, which thus set free passes int" solution in theacrtim. 
The dbc of stroma when separated from [be bicmoglobin ha«.aEweharcJi 



«U. an ot»eurclir «iH>ne%- Uixturp ; but w« ')» ool know aocuralcty th« cxscl 
eowliUnn of lbi> Nlffuit in the iiitacl oonxiKlo nr how it holde thi> hiemo- 
sloUa. Tlwn b nrluinly poilvliniu- mi'inhniiK; nr envelope to lltcGornugcIc, 
nr b]r expoung bliM>il toabigli lemin-nittin!. tU>° ('., the oorpuBole will break 
apialoil>on4>rlcMs|>bmciil pientt.eiich still i.xitii>itlin);ijf Mroinaatld b»RiO- 

Tbtt qouitily of nromn ncccsMrv to hold a qiiuoiiiir of lunooglobiti w 
«ac«T<iit)p1y small. Of ili« total Boliit inaticr of a corpu»d« tuon than 90 

Cr cent '» luFtnoglolHii. A red comiMrle in fad is a ijiiantity of hieniouloliin 
U (ogvther id the form of a dbc by a rainiinal ainntiiit of itroma. lience 
wb»l«T«r fflK;t ihtt stroow per te may have u^ii the plasma, this, io the 
ease of manuuala at all ereuti, muu be iiui(,'mticaiit ; Ihe red corpuscle is 
pcactirallr Rtniply a carrier of hieinoirlubiti. 

i SS. "file avemgie number of rvd ci>r|ftiicl«a in hiinian blood may be 
probsUjr put down at about 5 millioitu in a cubic niillim(4re (tli« mn^ in 
diflcnal ntauimals i« mid to be from '-i tu 18 milltoii*), hut the relation of 
eariNHol* to nlaama Tarin a good deal evi-n in hralih. nnd very much in 
dinw^ ObriuutlT tba relation may be allwicd ( 1 ) by mi iiitn-nim nr decnaae 
of tba pliRnn, 1 2> by iin net mil decrcaieoriacmucof red oorpiisrlr*. Now, iliv 
fcrSMT nuM rmiucnljy take nlacc The blood, as ire have nln-mly iir){i.'d, is 
always bring acted upnn by changm in the timie* nn<l. indccl, h nn itidi^s df 
thomt ehangn : bCDCv the puiMmi tniiet l>e «>iiliniially chnnging. though atwAVN 
sUiviiW III n-luro to the nurmni L-oiiditioti. Thus irhcn a Inr^-r >jiiiiiilily of 
wmtar b •lischareeil by the kidney, the skin or the tK>wols, ttint water citncs 
rvmflv from the filtMo), iim) tho drain of water must tend to diminish ihn bulk 
iif tDO plosniii, anil ri to increase the '•eialiit number of red corj>iiscU')i, 
tbmigh tlir etftfct is pmbnbly mod remedied by the |iaf«a^ of natcr from the 
tiiauf* ititii the blixxl. Ho ai^ain when ii Inr)^ i^unntity of water is drunk, 
tbia piwrs iniu the blood nuil li-nil.-> lempDmrily lo dilute ibe ulasraa (and so 
to dimiaish the ntniivc nuinWr nf red oorpunclev), iboufch tbii ooiKlition ia 
ia tnni snuu rf'a>edir<l byihe|<a»>iigeof tbeauperfluAiu> fluid to tbu ItMuea aiMl 
axcrrtury organs. The greater or liw number of red curpuide*. tiKn, in a 
fhren bulk of blood may be >iiuply duo to Iimi or mnn^ pla«ma, Init we have 
rraaoo tu think tluil tbe iictiml nuiuhor of ih*- eorpiiM'hv in iIh- blomi does 
Tan^ fmra lin>c tu liuH-. Thi> in rr-|>i.-cially m-cu to t-ortain formii of disease 
abieh may bo spoken of under tho geneml k-nn of anicmiii AWri! being 
Mveral kiuils of aoatmiai. in which the number of red corpuscla is dislincUy 

Tba rtdorsa uf blood mny. hone^'er, be Influenced not only by tW uuml>er 
af red corpuscles in each cubic millimetre of blocMl, but also by tlic amount 
af haaM)|[lobin in eneh corpurele. and to a le» degree by tlie siio of llie 
rorpBSCWS. If we compare, nilb a common standard, the rednMs I'f two 
wpmtbamat of blood unequally red, and then determine tlw relative numU'r 
irt oorpuaclta in each, we may And that tbe len red specimen has u many 
rorposclr* as the nilder one. or at least the deflcieocy in redness is grtMcr 
than can Ik- accounted for by llw [inudty of n-d corpuscles. Obviously, in 
socb a cw, the ml corpuscles have too little ha-movl«bin. In Mme coaea of 
Boamia ibe dcKcicncv nf binnnglubin in each corpuscle a more Mriking 
tbaa tba acantincM of red cuq>u8c)ca. 

Tb* aDiulirr at (orpowln in ■ specimen of t>lo<Ml U dctetminH by mlalng a 
Maall but carriulty meaiiurtd <iu»iitiiv of the blond with a Inrjce <|iiantity of some 
iadiAravnt Auid. f.y,, a A per ceiil. soliiiion of tiiillum »ii1]i|iiit^. nnil then uclunlly 
cowntiag Ihr. corpii*olr^ In a kn'>Hii iiiiindiiiil Imlk of ttie mixture, 

' , pcfbaii", may b« mmt ci-nvcuii'otly done by Ihi- itii'ilmil gcoerally known 



■* iluit of iiuwen {HKtBKicjUMattet) [Fig. $}. ltnproT«tl b; Maluwa. A glan 
bII<1«, 1b • m«uJ rnun«, ii rwtd into minute rM:Ui»t«>, •■. y.. \ mni. Ii^ | mm., m 
H toglvf &conT«nl«Dt«mof Aof o*n""^ ■"■"- ThrrcuiuUI x^vm in thernm* 
paraitt a novcralip to ht bratiftbl to ■ fixnd diatnnce, <- 9. i inni.. from the Nuifaoe 
oflbraliilc. Tb« blood bavinr b«4i diloinl.f.^. tu lUO iiin«* itn ralonie, • amall 
iiuikntiljr of die dtloieil ^«Dtl tburuusbl}' mlivai blood, iofflctent to occap.v fully 
UM ■pftM between tbe eurenhp aiM the glaaa alidfi whed lh« formrr i* brouEht 
lolia properpOililMi.ia placed on tti«al>ile,«tid the oovenlip broaght dowa. Tb« 

trw. a. 



A liHWllbt ■ Wu rtot Uw iHlWlin mliiitan; fl. oiJlltJT kiIr foi <.> ..- irL.v ),1:m>1; c. mil 
allb OlTtiluni on *Me, mv««ittuB uid upAiup: D, rami (ob^i iiilucliiiit. ^ inlxtri P, siMrdnl 
■■•Mr'podnti-l iiordls fOrMlcilnxBniKV.) 

rolumoordiliitod blood now lying over «acli ortfafirfctaneliw Kill be 1)9 I ^ X' J) 
of m cubic mm. ; and if, wb*ii thr< i">r|HiM;lM have ftulMiik-d, ll» number uf cur< 
piuelM lyinn within ■ recungte be L-oLinto'l, the roHuli irill cive the number of 
cnriKuclM pievioualy dlslrltiuted through tJo of a cubic mm. of the diluted blood. 
'riiiH mullipliwi by lOU will give the nnmber of rorpa»clM in I cubic miu. of l)i« 
dilutetl blood, and wain iDultipHnl by lOO tho number in 1 cubic mm. of ihr <>ntiro 
blood. Il io advinibtn lit count lli« Dumber of cofpuMle* in iier«nil of lb» rr«- 
tKDglM, ami to lake ibe average. Fur the c(tDveui«nce of counting, each mtansle 
la aubdivided Into n number of verv amall aquaroi, r, y. into 30. t»eb wtUi a aide 
of Jk mm . Hiid DO an nrea of ,Jlg or a aqnarv mm. 

Siner (Iw actual numlier of tM cnr{Hi»cle« in 1 specimon of bloiMl (irlilcli 
may be tjiken lu u Ntm|)U- of ihi; whol« blood) tssomelime* more, aomctinxM 
len, it is i^bviouH that either n-d (.'orpuwtea may be teRi|><>ninlv' withdrawn 
from and relunivd to the grncnil blood current, or that certain re<l corjmHctea 
are, aA«r a while, matlo uwajr wilh.iuid that iiea' oiiim ttiko thi-ir place, We 
have no aatieficlory cvitk-noe of the former heint; the ca»o in normal condi- 
tions, wbereait we bavo evidence that old cor|>u<clM do ilio and thnt new ones 
nre bnrn. 

^86. Th« red oorpmclee, we have already siiid, arc cyiiitinuully en-fa;;ed 
in carrying o»yj[e«, by moans of their batmoglobiii. fnno the long* to the 
liaauea; tlie^ load l)i«mBelvea with oxyK«n at lh« luiiii* and nnloiid at th« 
tlMUCS. ll u extremely unlikely that tbia act should be rvpoated indeliHltely 

rnt coRpracLcs or rnic blood. 



villtfKit leoilins t» chkOfrefl irhicti may be fiiniiliarly described lu w«ar aud 
taar. nntl wtiii:!) woub) ulLintalely leni) to the denili ut t\\^ turpiisclw. 

Wfr ftbull hrtve lu stale Inter oti thnl ibe liver didcliaripa into the nlinien- 
tmtj ivnal, lu a conMiiucut of biU'. a (Nminiderttble ((uaiility ul' a pit;n)vnt 
knnwn n» fiUirttbiH. and tliat thin iiuhi>iauoe liiu tvuiarksble rolatioiu with, 
»'■ I. majr he rcKiinieti as a derivative of Acmwi/ui, wUicb, as w« bav« 

•r< . • , ii a prciiliK-t of th« deoompotitioii of hn»uoglobui. It appcan 

)«T>faabl«. ID flirt, that ttic hilinibfn of bile I aud thin ii» vtir nUall woe i* Iba 
ctilrf biltarr |iif(UH'iil, hihI ih^ source of the ntlicr liilinry pifjnicnls) is not 
fonnnl wbollr nin-w in tix^ budv, but id maiitifucturtHl ia w>inc ituy ur oilier 
ODt nf lueuiatiii derived from liiuii(>gli>biu. Tbt» mtuil cfiUiil n diiiljr onn- 
•anptioB of a consiik'ntblo minntilr <>f hienioglobiii, and, »inec ivc kiiov,- no 
Other sourt* of bHtuogtobin besides Uio red corpuocW, and have no uvidutiuu 
of rrd eorpusclflt coDtinutne to exist after having lost their hemoglobin, 
(Diut, Iherefiirc, entail a daily deatniction of mnny r«d vorpusclec. 

Eveo in health, then, n number of red oorputcJes miut be continually 
duppearinj; ; and in diseaM the rapid and f;rent dimtmitinn which may 
take place in the ntiniber of red corpusctea »Iiowb that large destruction 

We cannot at present accurately trace out the steps of this disappearance 
of red eorpusclca. In lli« spleen pulp, re<l curpuscles have been seen id 
varioua wiMgn of disorganiiation. m>iuu of them lying within the suhetaiwe 
of Urge coRirleflB mrpuscles, aud as ii iT«re beinj; eau-n by them. There is 
alsoerMence that deatruction takes place in lb« liver itMlf, and. indeed, 
alwwbvre. But the subject lias Dot yet been adec[untely norknl out. 

997. Thia dralniction of red corpuscles ncovMitatisi the birlh of new 
(nrjiuivlM, to kei'p itp the uominl mpply of bnnoglohin ; imd. indeul, tlie 
ca«n> in which after even grcnl loss i>l blood by lieioorrhage n h4«lthy 
ruddiiMB* return', ami that often raindly.ehoning that the lost corpiisclta 
bavr htva replaced, as well as the cows of recovery fVnin the disease ana-min, 
tifnre that red corpuscles are, even in adult life, bom soinewhero in th« 

lo the deTClnpinf; embryo of the mammal tlie red corpusclee of lite blood 
af* not hKniof;|(ibin'huIdinK non-uuclealeil disra of stntma. but colored 
DucUaled cells which have artsea in the followinj; way. 

In o-naio re^oiM of the etubrru there are formed neata of nuclei imbedded 
in that kind of material of whii-h we have already (S h) spoken, and of 
wbMi we shall have B){»in Ut ii|N:ak, aa unililPeretiliated protoplasm. The 
Tf^f*"' faalnrrv »t' ihi* uiidilli-rvntiiUed )irotu[>hu>m are due to the maimer iu 
which iu livio;: biuin 1.^ -'> . in i.-arryin;.' iin lUi omlinui-d building up and 
bmikinii diiwn, di-|iii«a* of itiw:lf. iin linid. and ilti priMbn^ls. These arv fur a 
■ hil«i to arranged M to lafm a cnlorlivs iniu« with niinuln colorltna soli*) 
(lartjclra or c»l^csa vacuole* Initieddn] in ii, tli<- whole having a granular 
appaftnUMv- Afler a while this granular-lnokine protoplaum I* in laqt" 
OMMim gnuliially rvplaced iiy tnalcrial of dillvrcnt optical uml chemical 
cbaract^w. being, fur inrtnnce, more homoenMous and lcw"^nanutar" in 
appearatKe : this new material i* stroma, and as it is formed, there it funuod 
with it, and in SOUa way or another held by it, a ooloriiif' matter, bamio- 
KliAin. We cannot at piwent say aoylbinc defioite as to the way in which 
and |1m> itefie by which the oriffinal pnilopbfm ii thus lo a large ctlcnt 
diArantialM] into stroma and hmnoclobin. All we know is, that the exist- 
of what we have calM livinj; •ttbstanoe b nectasory to the formation 

atrena and hiemo|{lobin. We, therefore, seem juntiliiil in speaking of 

Bvinjt Mibstant-e as manufaotnrin;: thoe aubalanoM. but we du not know 

ln« living sul»tanc« tnras itself, so to apeak, iiilu stroma, or hoetno- 



globin.or both, orwbotbkrbyHmcsKnCT, tlii' iinlnn! of which i* at prcufciit^l 
unknown to iix. it cnovtrU some otihr nuiti^rinl wliicli i« prcwtit in the | 

C>lo|ilium, and which wc may rvgiint lu fwM\ for itself, into oue or olhcr or 
h uf tliCTc b"idit'-«. 

When this ilitlorcniion hiu uk«n pbuv, or while it » stjll gotnc od, Ute 
matcriHl in which the nucld an imbodded diridc* into te]>itratv cetl-bo<l!M 
for ihe eevernl nuclei ; and thus the n«st of nuclei is traiigfornied into a 
group of niicIcal(Kl red corpUBL-les. each corpuscle coDHieting of a uucletw 
imbedded in a ha<nia};lobin-holdiDf; atroiun to which is »till attached man or 
lesB of the oriKinal uodifltrenlialed protoplasm. ^ 

8tiU later on in the life of the «mhrvo the nucleated ml oorpuavles *reH 
r^laced hj- nrduiary red corpuscles, Uv n on -nucleated diaca coinpoaeil aloioat 
exclutivelv of htcmoglobiuholdiDi; slromn. Ilovr the traotifuriiiution tnkus 
place, nud^ e^jieoiully how the the nucleus corun to be abwnt, u at pnveiit n 
matter of couniilerable dispute; Uien- is much, however, to be (aid fur tlie 
view that the iiurmnl red ciirpiiscle i» n portion only of a ell, thut it in n 
rrwment of cell suhniance which hav been buddcil oil' and sn haii Icll tin; 
nuiileuii behind. ^ 

In the- ndult, as in the cmbri-o, the red corpuKcles appear to be formed oat | 
of nn7(H-diiig colored nuclenlea crllt>. 

In the interior of bone* is n pci-iilinr ti«tiic called marrow, which, in most 
pari* being very full of blo(Hlvc*<<!|-«. is called rnrf umrrou-. In this rwi 
marrow the capillaries and minute veins funn an inlncate Inbyrinih of rolu- 
tirely wide paoages with very thin walls, and through this Inhyrinlh tho 
How of blood is ci>mparatirely slow. In the passages of tliis labyrioth are 
found colored nucleated cells, thai is to say, cells the cell substance of which 
has undergone mom or Ices diSereniiation into hwmoglobin and stroma. 
And there sceiDs to be going on in red marmw a multiplication of such 
oolorad nucleated cells, some of which tnu)i>foriiie<l, in sume way or other. 
Into red uou-nucleat<><l ilisua, that b, into ordinary rc<l curpusclea, pan* awny 
into the general hhwul ciirr«-nt. In other wonln, a formation of red i'»r(>t>s- 
cIM( not whoUv unlike thai which tiiknt plaoc in the- cmhryo, is in thi^ iidull 
continually going on in the red niarmw nf (he liuniv. 

According to flome ulnorvem tbi- ciilor^'d nucleated wlls arise by division 
in the marrow from colurlc^s cells, not unlike hut probably diilincl in kind 
from ordinary while corpuscles, tlic formation of biomoglobin taking pl«e« 
subsequont to cell-division. Other ohsorx-crs, apparently with reamin, urge 
that, whatever their primal origin, these c»1ore<t nucleated cells arise itiirinc 
post-em bryooic life by the division of previous similar colored cells, which 
thus form in ihe marrow a dislincl class of cells continually undergoing 
division and thus giving rise to celU, some of which Iwonme i«d corpuscles 
and pass into the blood stream, while others remaiu ia the marrow to undergo 
further division and so to keep up Ihe supply. Such repeatedly dividing 
oells may 6tlr be called htematobltuU. 

A «imilar formation of red corpuwlea has also been described, though with 
leas c%'ideiic<>, as taking place in the spleen, ngtecially under particular 
clrcumstancm, surh iu< Hfler i;i^ut loss of blo(Hl. 

The formation of red eorpu»lw i*, therefore, a t)>ecial procen. taking 
place in !>|>ei-ial regiims ; wc have no Mtlsflictory evidence that tbc ordinary 
white eorpuseln of the blood are, Ms they travel in tbo current of 
circulation, tmii^formcd into red corpuscle*. 

Tho red corpuscles then, to sum up, are iix-fiil to the body 04i acominl of 
the htemoglobin, which ronslilutes to nearly the whoU.> of their solid matter. 
What funciiiins the Bironia may hnve besidn the mere, so to speak, mechani- 
cal utie of holding the luemojjlobin in the form of a corpuscle we do not 







kawr. Tbo prinurjr uw of the bn-moglobio is to curry oxygen rrom tl>c 
UiBp Id the toauM, aod il would appear tliftl it ie mivtmitiKeout to ibc ocoif 
«aay ihat th« hsMnoclobiii ebouid b« ss il ir«re boltled iiji in corpii«dc8 rittWr 
ilaa timpir difflufid tlirougb (be ploAtn*. How Umn it cor|Mi8ole nii>y livv 
tmnylnc osyjreii we do nol exactly know : the red cor|iuscl«a of one aniraiil, 
r. y.. A hir^l, iiiJMtol into ibe reoMk of nDotli«r, e. g.. a mflininal. disappear 
within a few days; but this aflbrds no roesaure of tn« life of a corpitMle in 
hi ova bome. Kveutually, however, the red corpuscle dies, iu pinec bting 
MpplUd by a new one. Tlie hieinoglobin svt fVe« from Uie dead i'nrj>uBdea 
a|Hiwii to have a Kcondary use in forming the pigment of the bile and 
{Mfldblr other pigment*. 

The n'hde or CtJarteu Gnjnuttff. 

t 88. Tbu white corpusol«s arc far l«aB numerous than the red ; & spect- 
mra of ordinary healrhy blood will contain several hundred red curpnsclea 
In rmeh white curpuscle. ihotifch the proporlioo. even in health, varies coaud- 
«rably onder different circuutslaoces. rHiiKinjt from I in 300 to 1 in 700. 
But iboujrii )<!» numeruus, the while i»r|tii<<.'lefl are {>robably of greater 
iaipavtaorr to the blood ilM^lf thim are the red corpn^Ies; the latter an 
(ftM^ Umiteil to liie special work of carrying osypti froni the ItiUKS to the 
while ibe ilirmer prolmhly enerl a oin^iili-roEle inlluence on the blood 
Uaelf, and help tn muiaDiiii it in a prti[ier c<in<litiiin. 
Wb«D Men in a normid condition, and " at r»t " the white corpuscle is a 
«ll, spberical, colorluw mow, raryinK in siie, hul with an average diameter 
of abMI 10>. and prrwmio^ jtencraTly a lint-ly but ;«imetimea ■ ooartelr 
^tmnular appcanuici-. [Fig. 9.J The surlincc. even when tbo corpoiolc ti 




«. wbUtcnnmirtnor kiinwnMond; il. red roryiBolio (hl(h |n««r}.) 

pHftctly at rR<t, t» not absolutely smooth and cvrn, but lomewhat irregular, 
thvaby coniribuiing to the granular appcsmmr: and at times thr»c irrcgu- 
lariUaaa ar« exacgcnitixl into protulwrenccs nr "pwiulo|KHlia" of varring 
rise »t form, iKe corpuscle in this way asmmin^ various forms without 
^•Ogiug its bulk, and br the nssumption of a senos of fomu «hining its 
pWc Of iheae " amwbold moveinenis," as they are called, we iball have 
ta spekk later on. 

In oarryiug on theoe Brmeboid morctaents the mrpttscle may transform 
ilsalf AtKO a spherical mass into a thin. Hat. irregular plate : and when this 
cecan there mnr be seen at tintes in the midst of the extended finely granu- 
lar RiMa r>r rW/ Oddy, a smaller bwly of different aspect and refhictive (Mwer, 
the Nwe/nuL Tlie normal prcaencie of a nucle<i!t in the white corpuscle mar 
■lao be shown by ircntiug the ciirpusele with dilute accctc acid, which swells 
op aad renders more transparent the cell body but makes the imdotu more 



refniclivi.' an<l mora Kliarpl;r drliiiiH). imd »> iuok iitiupii-uouK, nr by llie ti*» 
uf Hininiiig KMgenU, the niinririly i>t' nhicb iiiain ihc tuioltii* niort- ri-mlilr 
ttud luuri- deeply lliiiu ihr nrU IkhIv. In whnt jxrhapw may lie CQtii>i«l<^ri->l a. 
tvpivul while curjiiiK'Iv, Ihn iiuclvu* w a i>pboricii] ninw about 2-3 f in 
diameter, (Hit it variiii in aite in diflervnt ixirpiMicU^. and not iin(W-i(\ieatly i» 
irregular in fomi, at leiW after lh*t nction of rciigt-nt*. It oci-iwionnlly 
■I>pcan> ai if obuut to diride into fmginrnto, imd soDiclimcg a (7nr|>u»de may 
cunliiiii two or rrvn more (then gi-ncmllv >niull) nuclei. Though tlainiog 
rMdily with Rlaining niigcnlv. the nuclcui of nii onlinar^' irbit« cormisclc 
iloi-B not divw the nuclear network which u w cluniclcrialic, m ne »hall mv, 
of tbo Duclej of many eelis, and iihieh in tbew i« ih^.- ]>arl of the uuc]«us 
which especially stains; in the clwely allic<I lymph corpuftclc*, to which vre 
shall have inimcdiaiely to refer, a nuelcAr network is {ireacnt. 

The cell bo<ly of the white ciir|ni«cle may be taken as a good example of 
what we have called undi Re re minted protoplMm. Optically, it con^ista of a 
unifonnly transparent but Eomewhat refractive material or basis, in which 
are imb^ded minute particlee. generally spherical in form, and in which 
aumetimes occur minute vacuoles filled with fluid : it is rarely, if ever, that 
any distinct network, like that which is itomelimes obwrved in other cetla, 
can be seen in the cell body of a while curnnsele whether Gtainedor no. The 
Imbedded particlee are generally very email, and f>>r the must part distributed 
uniformly over the cell body, ^viu)> it the finely granular atipecl spokea of 
above; Mtmeliuiee. however, the particles are relatively large, makin); the 
oorpuaclea coarsely ^^raunlnr. the ooanejmnuleii \mi\^ l're>(iitntly CMifiiied 
to one or another {Htri uf the cell body. Titcse partiileF or granule:}, whether 
coarw or fine, var>' iu nature ; some of tlieui. as shown by iheir greater 
refractive power, ihetr >iaiuiDg with osmic acid, and Ibeir wilutiwi by miIv 
«Dl( of fat, are fattr in nature; others luar similarly be vhowii by thcirS 
reaction* tn he pmteld in nature. ™ 

The material in which thcw granuln arc inibetlded, and which fbrntf iho 
greater jiarlof the <-ell bualy. ha» notpeeini optical features; xofar aacan b« 
ascertnimd, it apix-am under the micrM>ro|>e \u be ho<nog«-nc<His ; no definite 
structure can be detected in it. It muKt be bnmr in mind that the whole 
corpuscle connsis largely • f water, the total mlid matter amounting to not 
much more than l<i per ctaL Tli« transparent material of the cell body 
must, therefore, be in a condition which we may call fwmilluid, or semisoliit. 
wilbout beinc called upon to defiao what we eiactly mean by these lemtt. 
Tbis approach to fluidity appearv to be oxinertcd with the gml mobility nl* 
the c«ll bmly. as shown in ils anxrhoid movements. 

$ 26. Wlttn we submit to chemical examtnalion a sutKcieni mass uf white 
corpUKlee. «paraied out from the bl<<wl by special means and obtained toler- 
ably free ftvaa nd coqiuackB and plasma tor apply to the while blood-cur- 
piudM tbe chemical r«sulls obtaiDM ftvra the more easily procure*! Iym]>h- 
corposelea, which, aa we shall aee, are very similar to, and, indetd. in many 
wajra niated to the white eorpiuelea of tbe btood i. we fin>l Ihul this amaJl 
mImI matter of tbe corpuscle coomMs largely of certain pnxeidt. 

One uf theee |)rDtd<U is a body dtber ideniioal with, or closely allied (n, 
the pruieid called mjnMN. wbicb we shall have lu etudy more fully in oon* 
i»ertiua wtih muscular tiMut At present we may umplr aay thai mrcttn !« 
a body intermediate between fibrin and globulin, bein^ Icwt iviuble iluin the 
latter and more soluble iban the former ; thus while it tr hardly at all wiluhlv 
is a 1 per cent, wlution uf sodium chloride or other neutral Nilt. it is, unlike 
fibrin, spctdily ami wbuUv dimolred br a tO {wr nal. mlutivD. My(«in is 
fbrtJMf iniervtiae beoitiM, as we shall sew, ju>t a> fibrin is formed in the 
douieg of bluod tnu fibrinngan, so mjixin it formed uut of a prvenliDi; 



mjMiiio|[«ii, iltirinK m kuul of cIoIUuk wbidi lakes plnco Lu iiiu»cular fibro 
wd vkirh U itiukeii of a» rigor inorlia. Aud w« bavv rmituii* fur ilihikioK 
tKst in tW living white biMiil-coriiuMic Iberc dott exM a body idtnitciU 
Willi or kJli^'d tn iiijrudiDiigeD, wbicn nc mtty *pc»k of uh Iwing in li fluid ena- 
ditioB : and whicb nti thr dcatb of lliv ttir|>*'*c'*= 'i cnnvi-rlrcl, by ■ kind of 
eloUlafc iaio myoain, or into nii nlliail hmly, wbii-h boiug wlici, give* tbs 
bodj « the corpiucle a »lifliii-w mul rigidity wbtrh it did not ponoM during 

BmUm thh mrmia or Riyoein-liko protrid, tbc white corpunclce nUo con- 
tmia nlhtr parngl'ditilin iiwif or some ofh^^r member of ibe globulin group, 
■* well u n tKMly or b'xliv* like or tdentictd nith Mruin-nlbuniin. 

lo Midiliun, tbt-rr is prciwiit, in somoirhat c»nsideniblc quiuititr, h Biib- 
fltaiK* of m [peculiar naturv, which, sinoe it it confined lo the niiefe! at lite 
CM|» iwe lw. Mid further ^eems lo be prewint in all Duclei. Iihh been called 
mmtUim. Thit uuclein. Khicb lhou);h a eoiDp]«X Dttrogenmia body h very 
diflhnal in rompoeitiou and nnlure Irom proteids, i> renitirknble un the on« 
bani for being a very stable iuert body, and on the other for eonlaining a 
brg* qoaniily (aceording lo BQue obeervers nearly 10 per cent.) of phos- 
pboma. which app«an to enter more cIokIj into ibe ctmclureof tbo nM>l«cule 
Una it does in ta« caee of prulei'Is. 

K«xt ID importance lo ine proldd», os constant constituents of the whitfl 
corpoacloi. c.x>Rie oerrain fala. Among theae the nioflt couBpieuous is the com- 
plex falty body kcHAw. 

Id tbe uueof niany corpuscles at all eveiiU wc have evidence of tbe pres- 
^KC of a nieniber of the large rrmip of car)>uhydraie». comurising slarcliei 
■ad njpir, viz., the tturuh-likc body gli/aigeM, which ne shall have In study 
man fully hemner. This glycogen may ext^t in the living corpuscle a* 
gljrtngvn, hut it m very apt, aAor Uto dcatli of ihe corpuitclc, to become 
cfc— grd bj h) dnuiou into roma torn of sugar, nicli as nialtoM or dextrnee. 

I itli the tub of the white corpuacles is chiiracteriu<l by coataioing a 
frlativvly large quantity of |>otnseiuni and of phosphates and by biHng reln- 
tiralT pinr in chWidea and in sodium. But in this respect thu corpuscle is 
mmij an example of what weuiH to be a general role (to which, however. 
llMnrw tnay be exoeplMMia) that while tbe elements of the tissues themwlvcs 
are rich in potassium and ph(*)phat«fl, the blood plnsma or lymph on which 
ibey live abounds in chlorides and sodium salts. 

i 30. Id the broad features abuvc lueniioned, the white blood -corpuscle 
may be lakeu as » picture and example of all living tissues. If we examine 
llta bisbilogica] elemenls of any tissue, whether wv take an epithelium cell, 
or a nerve cell, or a cartilage cell, or a muwrular libre, we meet with very 
■ittiibtr feaiurea Studying tbe element morpbologteally, we find a nucleus' 
and a irll lioily, llw nuHcui having the general cbaraclera described above 
with fmjuetilly other charactvrw iiitniduood, and the cell body cunsiHting of 
■t IcMI more than one kiml nf niiiteriiil, the mulerialH being aoroeiimea ao 
dinieard ■> to produce the npiiciil i-tTtTi nimply i>f ii trauHparent moss in 
■rbidi granule* are iriil><^lili.-d, in which caM- wi- niieak of liie cell UkIv us 
pretop&niic. but at «[hi-r limiv f iirrnngnl that tlie oil Wly |iodfiesaes dif- 
wmllated structure. Studyiuf; the clement fmm a chemical iwint of view. 
W» tad protcid* alwny* prcMnt. and nnioog lh««e bodies idenlicAl with or 
atm or tess closelv iilliiil to niy<«in, we generally have eridence of Uw prce- 
«Dre alsn of fat of'winie kind anil of fiioe memltnr or members of tbe earbo- 
liydrate gn'uji. niwl the wh always cunlains potaiwium nitd |ili<M|>)mtfii, with 
•Blpbatae. chloridu, sodium, and cnlcium, to which may If adtled magnesium 
au iron. 

■ Ttw m lmn w rf ■ultfniiclnu ttrusmwi do» wnl tWnA tlw |i »i wi t wyiim»nt. 



We sialwliu the lutroduction Iliat liring matter is alwsya un{ieT;gtNii 
clieniiciil cbaDjte; (liia continued chemical dianiice itc tntty ileiiote by the 
tonn nietabolirm. 'iVo fiirtlier urged tluit as looe » lirins muter ii aliv«, 
llti^ (-beiukal clituit(e or luelabulttin u of ft double kiud. On tlie one band, 
till- liviii); NubntniR'f Jit CMiliiiually breaking ilimn iiiti^ rimplcr bodi««, with 
a nutting froc of t.-uergr ; this jmrl uf tht- miTiiihoU^m w4t may apeak of lu 
roftde up of katabolio chaTigi-N. On the other baiiil, the living •iib^taDoa ia 
OontinuBlly building ilvcilf np. I'mhiHlving ciivrgv into iim-ll' and ho rcplcB' 
Hhing it* Htorv of riicrgy ; thi» part nt'' the metabolism wo may rpcak of at 
iDiide up of nnaltolln chang<3>. Wo alw) urged that in every picpp of living 
tiaiUfl there might In' < 1 ) tha actual living Kubtslance itaclf, (2) matoniil which 
is nn«cnt for the puriiose of becoming, and is on the way to boeome living 
Butistancfl — that is to snv, food unilergoing or about to undergo anabolw 
vhang««, and (A) nintcrial irhich ha» rcaullod from, or is reeuliing from, tba 
breaking down of the living substance — that is to say, material which l;aa 
uudergone or is undergoing kalaholic change;, and which ne speak of as 
waste. Id using the wor<I "living subetance," however, we must remember 
tliat iu reality it ia not a Bubslance in the chemical sense of the irord, but 
material undergiiing a series of changes. 

If, now, we lutk the <)ueeuoD, which pan of the body of the white corpuscle 
<or of a fimihir element of auother tiai^ue) U the real living suh^tance. and 
wbieh jitirt U ftiod or waste, we ask the question which we cannot lU vetdefi- 
ni[«lv anawer. We have at preM^ot no adeijitnte mornholozlcal criteria to 
enable ua to judge, by optical characters, what iji really living mid what b 

On« thlDg we may )ierbajie stay ; the nmterinl which appears in Uie cell 
body tn tbe form of distinct giiuiu leu, merely liHlgei) in the tnorv tnuisparcnt 
ntatcriitl, eunuot be part of the txmiI tivttig substance; it must lie cither food 
or waste. Many of these graiiulei' arc fat, nnd we have at times an opportunity 
of observing that thcr have been introduced into the corpuscle from the sur- 
rounding plasma. The white cor|)UBclc, as we have said, has the jM>wer ef 
executing amcelmid movements ; it can creep around objecia, envelope them 
with its own substance, and so pot them inside it^lf. The granulea of fat 
thus introduced may be suluequently extruded or may disftp]»tiar within the 
<XHpu8cIe: in the latter case they are obviously cliaiiged. and ap|>arently 
made use of by the corpuscle. In other wunU, thW faity ^rauulei are appa- 
rently food material, on their way to he worked up in the living substance 
of the corpuscle. 

But we have also evidence that dimilnr granuleti of fat rwv make their 
appearance wholly wilhiu the oorpuacle; they are priHiocta of the activity of 
the ooqmsele. We have further reason to ihiak that in some i-a-*eT<. at all 
events, they arise from lliu breaking down of the living Huhntancti of the eor- 
puBcle, that ihey are what we have calliH] v/wtU: prntluct*. ^t 

Rut all the granulcK vJnihle in u cnrriiiHcIe are n»t neci^warily fatty i^l 
nnturo ; aomo of them may undouhleilly he pniti^id gritnules, und it i* )>os>i- 
blo that some of tliem may at timoi he of carbohydrate or other nature, 
all eases, however, they are either fond material or waste products. An 
what i* true of the easily distingui«hed granules is also true of other sul 
•caiicat, in solution or in a nilid form, but so disjiosed as not to be optically 

Hcoce a part, and it may bo no inconsidemhie part, of the white corpus- 
vie may be nut living Guhstniico at all. but either food or waste. Furtl>er it 
does not oeoeesarilr follow that the whole of any quantity of material, fatty 
or othernbe, introduced into the corpuscle from without, should actually 
l>e built up into and ■o become part »f the living subatance; the chau^ 


Tirx c.'OBPi'act.Es of tiik blood. 



■at raw fnod to livhig (ubclance are, u we bare already mii), prolmiMy 

. u)<l it inaT Iw ibat after a ceHain number of cluingeit, frw or mnny. 

•nljr of tbe material it accepted aa wcjrthy uf iKing niu*!!; alivv, anil 

ml. beiDf; rejected, beconia at ODr« iradie matter ; or the malarial may, 

a aftrr it lia* under^oue this or ifaat rhon^, nervr acltially enter into 

tbr liriojt aubMutoe but all become wai^i' inaitcr. Wo miv wa*tc matter, 

but tliia (Ion not mean umIcm auller. Tho mallrr m formnl may nilbotit 

niarinit iutu the living mib>4aD0i! be of lonie ^uWidiarr use to tbc corpiiecle, 

«r M (NTobohly morv otltn bappomt, bcios diwhaiwu from tho cnrpuwle, 

Ba^ lip of UM- to Kime other part of the mdy. AN e do not know how the 

Uthiie •uh*taDi<e bailds ilMlf up, but wo aoem <>ompcll«l to admit that, in 

(•ttaia csfn at all cvi-nls, it is abk> in some way or other to produce 

rkiK)^ iin maleriid while that matrrlid is Mill oiiUide the liviiif; eulwiance 

M it were, before it enters into nnd indeed without ile ever actually entering 

inlallu! cotnpofilion of the livio^ fiub«tiiHce. On the other hand, we muol 

nptiOy admit that tome of the wnnte friibetances are the direct pruducia of 

kaiabolic changes of the livingt subelance il«elf— were aL'tuallv oure |>iirt 

'if lirtn^ mbetance. Hence nc uu^bt, |M>rbap«, to distiaguiJi the nruil- 

nf the aciiriiy of living matter into waste pruducta proper, the <lirecl 

of talaUilic <-hhn]:ni. and into hyc produda which nre the rcHullii of 

dfircCed bv the living nmtli-r oui^tdi' it^ll'and nbidi cannot, tbore- 

eODiiilercQ an Dcvrivarily i-itlivr iiimlHilic nr katatiulic. 

ine llttebemical chanclcni of Iht' living matter itielf wo cAimot 

_. make anv very dvlinit<> »talemcnu V,\: may av lliat the pmteid 

>. or rather t^r protcid nntrcnient i>r unli^colent* of my win, enter in 

■ay into iia stniclure, but we nre not jiiMiticd in Ntying thai the living 

labiluce cMiaisIs unly of prnlcid matter in n peculiar condition. And, in- 

tifcr-' '•'■ -'-oiitency with which aoiae reprewntalive of fatty bodies, and 
w- iintive of carhuhyilnites always appear in living tueue would, 

pnitij-. niiinrlrnd u« to m|i[Hi»e that these equally wiili proteid material 
*r» tanniinl til itM Htructure. Again, though the behavior of the nuck-ue 
m oiDlraati-d witli that of the ceW budy, lea<U u* to Mippote tlmt the living 
nhMaara of ibo former in a itifrmnl kind from that of the latter, we do 
BM ' "'tly in what iIk^ diU'iTt-nco coiim*!*. Thti niiclFiii, w we have 

•K. nvctfiii whiih. peiha|t», «c mav regard w a largely modified 

pnu-t . l-iii htfiuff a body which it> reinarkablf (or il» ftability, lor the diffi- 

I fall) oith whii'h it la changed by ehemicnl rcngcnt». cannot be regard«il as 
■I mnal ftut of the ecHenlially mobile living »ibslnnce of the nucIeuB. 
Ik !&■ nmneetion it may be morth while to again call attention to ibe 
kl tW the «or]:u«-U- contains b very large quantity of water, vix. alxHit 
MftrcraL ftiii of tbi«, we do not know how much, probably exists in a 
■Mcorin* definite combinaliou with tho protoplasm, siimewbal after the 
■MBcr nf, lu u«o what i« a mere illustration, the trater of crTstallizaiion of 
Mkib If we imagine a whole gmu^ of dillbnnt complex salts continually 
<gwfi nl in (uni in being cry«lalli»d aitd being decryMalliied. the water 
lkM«Bf*getl by the *allf will give UM a rough image of the water which 
MM! a and uul of the sobftance of the cor|iu>clc an the reault of its meta- 
MBcactiriiy. We might cull this " water of metaboliiini." Another part 
<^ Ifca water, carrying iu this esw suliftnni-eii in solution, iimlwbly exisia in 
ifarmoT (Dlerriicee too small to be seen nith even llic hiKbcxt powers of (he 
aitnacnpr. Btill another part of the water similarly hutdiag subMaoccs In 
mtaiiim cxbl« at linKs in dt-iiuiie spaces visible under the mtcroaoopo, Dton 
•rim rvf^nlarly spherii-ul. and called vacuole*. 
■ WakBTed«rlt thus at leugth uu the nhite cirpUK-h) >d the fir«t plaoo 
Baesna as we Imvo already eaid what takes place in U is in A atnao * picturo 



of wliut takes ;i1ni-e in *\] lirin;; elrucliim, nn>i iit ihc et-oiKl ploop 
ll)L' fiic-U whioli wre linrc mefilioDod help uh (o uiiilcmKifl how the 
ciirpiiM'U- may carrv on in ilic blond a n-ork of no im|u>riunt kiuii ; for from 
wliat linn iieeii aitid it in obviotin itinl the white curjKi^cIo is OJUlinunllv itrt- 
ing u(ioi) mkI Iwiti^' iiaed upon by ibe plasma. 

$31. To II II lie ret and. however, the vriirk of these while ror|>uH)ea, 
inii»t Ii^tni nbot U known of their historv. 

In »iiPci.-Mivc droiM iif bloml taken at (iiflerent times fW>in tlie same ini 
vidunl. llic number of colorlew coqiusde.i will be foiiii<l to vary ^t-ry luuc 
not only nOtlivdy to th<! red coqiuvoles, l>ut bIsu ab«i.>lut«]y. Th«y iiiu 
tbereforo. " come and gti." 

In treating of ttit; lyinpliiitic *yiit«m vc fhall hnvc to point out tlini a 
very largu iiimiility of tliiiii enllud Ivnijili, ci^tiliiinint; a vnry (,i>n«idrnible 
number of bodi(»i, very similar in thvir gmrral chiimctcrg lo the white cor 
]>ufic]eB uf the Mood, is being riinlinimlly poured Into llio vaxeiilar erntcm «( 
Ibe point where llie ihoratic durl ioinn lliu grc«t veiu« on the left ai\v of the 
ueok, and tv a k^ra exlrnl whcir llic olhcr tnrge lymiihaties join the venoos 
■VHleiu on tho right eiiie ol' th<- nock. Thetw corpuscle* of lymph, which, as 
we have just said. ek«ely rc«cnib)Ct and, indeed, are with difficulty distin- 
guisbeil I'niiD the while corpu^cloa of the blood, but of which, when they 
exist outside the vaHcultir eysleni, it will be convenient to speak of a^ Intro- 
eyttM, are found along the whole length of the lymphatie aystem, but are 
Diore numerous in the Ivmphfttic veesela aller theae have paaaed tlirougfa 
the lymphatic glands. 'Theae lymphatic glands are partly eompoHed uf 
whal '» kuown as adenoid tissue, a special kind of connective tatue arranged 
an a dc-licaie network. The inemheH of this are crowded with oolorlesa nu> 
clr-atcil cells, which, though varying iu slxe. are fur (he most part •mall, the 
nucleui) lieing surrounded by a relatively small quantity of cell iiilwUtiicv. 
Many of thv-w; cells show signs that ihcy are undergoing cell -4)1 vision, and 
vre have rcuMnn to think thai ivlls so formed. a<-(jiiir{ng a liirger Hinoiint of 
cell substance, become veritable Iciicjcytw. In other wur«ls, lencocyt** 
multiply ill tlic lymphHtic glandi!, and leaving the glands by the lymphatic 
vessels, make their way lo the Mood. I'att'hes and tracts of similar adenol^ 
liasue. not nrmnged, however, us distinct glands, but similarly oi'cupie^l b^ 
developing leucocyte* and similarly connected with lymfilialtc veawls, are 
(bund in various parts of the body, especially in the nmeous inombraaes. 
Hence. W'e may conclude that from varioua parts of the bmlv, the lyni- 
pbatios are continually bringing to the bhiiid an abundant supply of leiico- 
cyi^a, and that these in tbe blood become urdinarv white 4-orpUi>c1t«. This 
is probably the chief source of the white corpuscles, for though tht* nhite 
our|>uscles have been seen dividing in the bhxHl Itself, no large increase takes 
place in that way. 

£32. It follows that since white corpuscle:- nrr thus continually bciDe 
sduod to the MoihI, white corpuscltni must as continttiilly either be ilcstroycu, 
or be transfonncd, or mcsjh^ mini the interior of the blood vewels: otherwise 
ihe bloorl Would soon be Mocked with white corpusi'Uw. 

Some dn leave the bhimlvi^Mcl*. In Ircntiiii; of the circulation wc sball 
have to ]K(int nut that while eortiuscles an- abb' to pierce the wall* of the 
capillariiv and minute veins, nno thus to mnkc their way from the interior 
of tbe bluudvnw'U into K{iaces filled witli lymph, tbe "lymph spaces," as 
tbey an called, of the tiwiue lying outside the bloodvessels. This is spoken 
of as the "migration of the while corpuscleH." In an "ia6aiueil area" 
large nuiul>cr« of white corpuscles are thus drained away Uom the blood 
into tie lymph spaces of the tbsue; and it is probable that a similar Icaa 
takes pUoe, awire or less, under norma] couditious. lliese migratiug 

se migrauug oc^ 




f roDawiDK ibe d^-vioiii tract* of tlic lympli, find their wny 
bluod: toiDC or I hem, huwovcr, may reniuiii, and uridi.-ri^i 
vafioo* ebanra. Thus, in intlamcd iireni). when »u|iMinili<)ii rullowii in- 
flaaattlioa. t£« whil« <»r|iiiM>1c!t which have niixrsied may Wi^itm' "ihi» 
OMpOKlet," or. where thickoniiii; nud Kr<"*'l> follow ii|h>u ii)flnmmnli»ii, 
OMT, BflnQrilini; to uiiiBV iiulhoritleE, h6is>iii« tmmrormed intn (em|iiirnrv ur 
pvnnaiKnt tuMiu. ni|x'rin]ly cimncctivt- tlwue ; but this trantfitrmiitioii mio 
dtm b dlifiuicd. Wh^ii nn ititlBmnialiiiii sulMtdett withoni U<nvirig any 
dbct ■ few CT»q>uwl«i only wilt Iw found iu iho tinuo ; IhuM which had 
prwiottily mignU'd Diu*t, ilicrefuro, have lii:rn dii>[iijw>il uf in fonie war or 


In iMBkbg of the forniniioD nf rod corptucU-s ($27) we mw that not 
oaljr it la not pruvcti thai tli<* iiui-lcatcd oarpturclcs wliich give rJM to red 
VorfNncka are ordinary nhitv cornii»cle«, bnt that in all probabililv Ihe real 
banwtobluiv. the pnrcnu of rwi corpuwJcs, arc spvcisl corpuscW devel- 
•|icd in Hue »ituation]^ irhcro Iho niiimifiiclura uf rcl corfiuscles takea place. 
iio 6u, tbcrtri'ore. from an»uminK, at is eomelirncfl done, that ihe white car- 

ricl«a of llie blood ut« all of tnein on their way to become red corpiisclea, 
may Iw duubtei) whetlier any of ihem are. In any cii*e, hnwever, «rei) 
■•ktnt; atlowaa<« for thotw which mit^rate, a very coitiderable uumhcrof 
tb« whiu oorpuaeUa matt "disappear" in some nay or oilier frum ih<' blood 
Unam, Will in may, pcrhap*, siieak of tiieir di«tpj>eiinin<'e an being n 
•* dwintction " or " dlwolution." We have, us ret, no exact kuo<rlei]gn to 
■•iiiiti- ti* in tliv tuaitter, but ne cait readily imauiiie, tliiit uuun the death of 
'j'liaclei, ibc •ulwtaneea >'iinip(Ming it, after unilergomj^ chaiigra, are 
.._... i^l by and become part uf the planmiL If dc^, the ct>rpiiiicU's a« they 
di* noat t«i>eale<tly influcooe tlw coni|Mk<jii<iii and nature of the plnsma. 

But if (hey thus aliect the plainia in ihcir death, it is even more proba- 
ble that ihev influence it during ihoir life Beinj;; alive they must he cou- 
tiimally laliiuf: in and giving out. Ah we have already said they arc 
knonn to iu;;e9l. after the fiLthioii of an amaba, solid panicles of varJou* 
Unda, Micb a» fat or eariiiiac, pmeut in the pliuma, and prolwbly digcut 
Mda of thno particlca u are uulrilious. ItuI if ihev iu(Cfi»t iheM xilid 
etatUn ibry iintlably abn carry out the easier toak 0!* inf(e«ling diawlvud 
BtatMca. li^. however, ibi-y thua take iu. they niiist abo give out ; and Ihua 
br llw rvmiival on the oue huud of variotin niil»lanctA from the plainui, 
aod bj the addition ou tite other hiind of othrni. they niuat be iMnliually 
tafliMBdnK the plaama. We have aln-iuty :iuiil that thr nhite oorpuH-lr* in 
lfc»d U4iad a* ttiey dio are aupiXM^d to pliiy un imji-irtnnt jMrt in thv clot- 
ifnif of bkiod : Biniilorly they may during their nhiJc life be engngiHl tg 
t^rr*''"' ■■•<\ rhangn in the pmleiilit of tlic plutnin which ihi not lead lo 
di-' which prepare them for their vnri<m» uh'^ iu tb<* body. 

r,>.u-..--h.<^«l facia alforil Mi)p|Hirl to Ihii' vivw. TbcdiMMue callmJ leiicn- 
ntbcoiia (or Inkieniia) is chamcli-riccd by an incivaev of ibe white corpua- 
cin, both absolute and relative to the reil cor|>ii»claa, the incrvaae, due to 
■a sai;nenl«d production or poosibly (o a rrtarded dostruciioti. being ut 
tinea m xnul ai to |.iv<> thu blood a iiinkieh-gmy nppeaimnce, like tlut of 
Uoad aispd with pus. We accordingly liml that in lliia diauw the plasma 
if to Rtaoy wavH pr<ifoundlv alfevt«d and fails to noiiri^ the tisuea. Aa 
a ftirtWr illui-lratiun of tbe pomble acltou of the white eorpusclca we 
mmf (talir tliat, acciinliiig lo ^>me ob^rvers iu cert^iiu diseasea in which 
•imt« orgnnumi' micIi ns bacteria make iJieir api>e«>auoe in tbe bli>od, 
Iba white mrpuMrlra " lake up" ihew baderiu into their subMaaoe, aod tbaa 
pvMbahiT, hv irxeniog tin influence on ihem, modify the coarse of tbe dbtan 
«f wb><^ ihoe organism* ara tl>e ««sealiu) cause. 


If ttiu while uorputcJcs are thus eugugtd during lli«lr life in carryiii); fM 
iaiporUUit Inliora, vre may exiiert ihcm to diiTi-r in a[>))eHrance acoonjiiis to 
their CQD(liti»Ti. Some of tliu cur[»uid€M arc iipikcn of lu " faintly or 
*' finely" graniilnr. Otlior MimiM^lm are niwkwi nf tut" euanfcly " gmaulir. 
Iheirooll Fiibntance bcinu l(M<Ivd with c»i)iipinioii»lv diicrfie graoults. It 
may bo, uf coiinfc, thnt tncra nru tw» di»iinc't klDcIs of corpuitdee, baving 
dHfcmit fttnctioiJH ami pmrnihly diflVrent origioa and histories; Ixit sioco 
intcnnedialc fonnii nrp mtt with ontoinine a lew cunru gniniiln only, il it 
more prohnb)« timl llio otic tVm ix n pbaso of the olbrr; ihni a faintly 
granufar corpUHclp. by laklog in granuks ftom without or by producing 
granules within itself ae product* i>f it." mctabolitn), may become a coarcely 
granular corposde, 

Wlicthtr. however, the white corpu«clc« are roally all of one kind, 
whetlier they ure dilfereiit kind» jMrforming dilTerent functiona, mait- 
preaent he left au open question. 

Stood Plaltkt*. 

§ 33. [n a drop of blood oxamiued with care immediately after renioi 
may ho f>ccit a Dombor of esveedingly timall bodies ('into 3^ in diamrlpr 
fircqiientlr disc shaped, but Dometiincti of a rounded <ir irregular furni, hnini _ 
geuooiu in apposrancr when quite fresh, but apt tn aMiinie a faintly gniiiiilar 

l^irct. Tlier are culled blrivd platrlth, or itfooti 

|Ra 10. 

(tln'jHfu. Tni-y have been «ui>piK> bv sonie |M 
K'coniu ilcvi-hjpi'il into, iind.'iiidrcd, to be cnrijm 



HiiigfS of, the red curpufcle:', and lienrv have 
been called lucmutoblnate ; but this view Iiiib 
not been confirmed ; indeed, as ne hare seen 
(S 27), the re«l hse m a tob lasts, or developing 
corpuscles, are of quite a difltrent nature. 

They speedily uuder;;D chaDRe aOer reninri 
from the hodv. apparently dissolvtug in ihu 

StasTDB ; ihey hrenk Up, part of their Bubetjince 
isRppeariug, uhile the r««t beconiea granular. 
Their granular remains are apt to run togclhcr, 
forming in the i)Ia§ma the shapeleda inawes 
whirh have h-iig Wen knowu nnu descrilied as 
■■ hinipx of proloplasm." Br appropriule rw- 
ttgpiils, huwever, these plaieleta may he fixed 
and EilaiiKst in the ctiRililion in which the^_ 
ajipear afttT leaving the bcnly. ^M 

The aiiliNtaiire ei.ini[ia>ing them is [leculiill^ 
and, though we may pvrhaM ajicak of them ua 
iHiOAisting iif living nialeriiu, tlieir luitnre is at 
|>riiH-nt mmcure. They mayhcscfn within the 
living htoodve£Bels[Fig. 1(1], and tbercfitre miiM he regarded ss real parts 
the blood, and not as pr*idiict» of the change* taking place in blood after 
has been ahvd. 

When a needle or thread or other foreign hotly is introduced into I 
interior of a hlo^jdvevsel, they are apt to collect upon, and, indeed, are the 
precurMira of the clot which in most cases forms around the ne^le or thread. 
They are abo found ia the tfiromf/i or pings which sometimes form iu the 
bloodveiMb as tiUi mult of diseaac or ioiury. Indeed, it hu been main- 
tained that what are called whiU thrombi (to dislingiiisb them from 

m«i!< ilUKi-iri I'm Blriijip 

A. network «( nhrlii. tkiowa anet 
WMbtiiii aiaar lbs corT>uiclD» Riiui 
« |>rti>*nll»iicrt blood Ibkt iMa br«n 
■llcnrcrf lo cint: maniF of llin llln. 
Btmi ndlHtc Ifota miitll clum|B 
oftilowl lilatflcu, n iftDiu Otirrt. 
Uux) cuH'UWln ukI vlciiicntury 
|«l1ICta otIiIcKil plnlFJDU mltlilo 
a >iiibU lelu.) 




M, wlir4-li ftrc |>Iu^ of cnr|>iif>c)«« anil filirim are Jii rtfalhr aKi;ref;a- 
tiMu of MoimI jilniolola: nixl for various r»uiiiiti> IiIlhiiI pluUileu Imve been 
•Oppond tu |ilitT nn im)Hiniiiil jiiirt in tb^; clottiug of bltiod, rarrjing 
Mit Um work wbifli, iii tlil> riv|>ix't, U by nlh«n nltribiiicd la tlie wbite 
eorpinlw. Itut no vorr (kfiiiiii* xtaii-tiiKitt mii iit prc^iit hv- madft about 
Udi: uid. [lulaed, tb« origin ati<l wb>iU- iinturc of Uhvw bloin) iiUielciU a at 
pnaMil ofaMartf. 


1 91 We n»Bjr now paas brii-flir in review the chief cberoical clmrocK'n of 
Uood, reHMinbMnitg aJway? tlint^ ns wo hitvi; nir«iu)y urgod, the '-bief I'heini- 
lal iatunia uf blood ar« nUni'bed to ihv oban^^ « bicb it unilert;oo» in tbu 
wranU tfaaiiw ; these will be cuoHidored in connection with each tisHie at tbe 
BppT" prist r place. 

T ,•(! siM'i-itic K"'vitr of human blood i» lOW, varying from 1045 

lo I' < hin till- limiu of health. 

Tbr rxTAction of blond M h lloirii from (be bloudreMcta U found to be db- 
lioriK tli..ii;;b fifbly alkaline. If a dmphe plaoeil on a piac<! of faintly red, 
ht^ I liiniuit paper, and then wiped utf, a Muc »tuin will be left 

li.- It lilooil cuntaiiu a cvrinin ifuiintilv of gw^ vti., oxyt^i. car- 

bonir Bciil, and nitrogrn, whii:!h iirv b4>Id in the bluoil in n [let'uliar wav, 
whifh vary in itiirvri-nt kind-i uf blood, and »o itcrvu cfpuciAlIy b> dUlinj^idli 
arterial fn>ni veft«u> blmid, iiiid which iiiny be given off from blooil when 
esfwanl to an atnioipher*-, accord! nj,' to lh<- composition of llnit atmosphere. 
Tmm gatea of blixHl wi- Fbnil ntudy in ronnvetion wilh rvapinUion. 

the oamtal blood con«iHi« of c^Tpiudet and ptntma. 

If llMeDr|KHelw be suppcwod to retain the ani^iiol of water proper to then). 
bland iiuiy. in ^i-n«nil ti-rnt*. In- iMii>>idi'nr<i as con^istio^' bv woighl of I'roa 
abmi one-third bi oomewbal lens Ihnn one-half of eorjiuiclea, the feat being 
plaama. As we have alnauly kch, (he Dumber of ciirpusclea in a ajweinien 
of hinod i« fr'uml u> vary ennsiderably. imt onlv in different aniuiaU and in 
diAnuit inl*. but iu the aame individual at dilferenl times. 

Tbe ; ' - rnudvtst by the cloltinic of ibe \>Wni into «^iim and fibriH, 

I Si. The MTiiM eoniaini in HH) parts : 

FrBtaM tobMiMw 

hU. vMWua MtirwtivM, asil mliao oinlUn 

■bnut H ort p*rU. 
3 or I part. 
m larta. 

Tlw pnitiridi) arv pnrttgMtulin anrl >mim-tiibumin (there being probaM/ 
than lutp kind of M!nim*atbiiM))u I in varyiDK proportion. We miij, 
p«H'*'- r-niiihly "peaking, my lliat tbey ifccur in about equal quaulitie*. 

' <tis iind linking nt are the restilre of cloltinj*, niaiwive a» appear* 

10 U ..'■ • -'-l whii'h \a fiirme<l, it must be remembered that by far tbe greater 
(ttrt uf ibc clot consists of corfHiselea. The amount by wei;gbl of Bbrin 
ranitired to bind togeiber a number of corpusclei, in order to form even 
a larse. tirra clot, ta exceetliugly small. Ttiu*. the average •piantitv by 
■r' " ' : 'niii in buuiiiii blood is <«id lo l»e 0.2 percent.; tbe amount, bow- 
iin W obiaine'l from a given <|uautlty of pliumu variea extremely, 
ti>t due not only lo circuinsCaneet affecting the blooil, but 
I empluyed. 
l> are Manly, excel)! attar a nical or in certain palbolngical 
i I of the neutral fiiU — ileario, {lalmitin, and ob-io — with a 
Y ihi-ir n -ji'Tlivo nlkaliiie woapt. The i>eculiar cotuplex 
' r.' in viTv (uiill 'luantitic* only : ifae amount prcHQl of th« 

(be ^:ll 




peculiar iilcobol <'h<>1<«lenti , wliirli hiiK *a fiitty iin npiminiiKN!, is al»n sma 
Among the cxltaclivc^ jiriwiit in .iL-rum niuy W [lut ijohd nearly nil th« 
nitrogi'iiotiii nixl ollii-r i>tiii«liiiu'cii nhifli I'orm lli« i'xtriu?liv<'!> of the btxlf nod 
of food, riJc'li B« itn-ii. kn ntiii, >ii^ar. Iiu'ticacid. tic. A very InrgR Diirnbrr 
of tlic»c Imvt Item di#iiiv(.r<d in ilii- Moud under vitriquo cirvuiiiKtaiirn. (he 
cotixidcrntioti of which niu^t lie IcfV for the prcMiil, The peculiar oddr ttt 
blood or of Ecnini is prol>atdy duo In ihc prcwtire of volatile bodioB of tlic 
fatty acid wrie*. The laint yellow cidor of eeruin it duo lo a K[iecial yellow 
pij-ment. The tnoet charactvriittic aod imporioDt chetnical feature of tbo 
saline conGlitulioii of the ecnim is the pre|ii:<Dderaiice, at lea«t in man and 
most aniiiinli', of fodium mltii over those of potiuwuni. In thb mpvel the 
aeruiu offers a tnoikcd conlrnsl (o the corpuscles. Lees marked, but still 
Striking, is the abuodnnce of chlorides and l)i« poverty of phoepliates in the 
aeiuiD, OS compared wilh the coqiufcle^ Tlie mlti inay in fact briefly b« 
described ns cuDsUliug chielly of eu'liuin chloride, aitli ioiue amount of 
sodiiiin carboDste, or more correctly Midium hii-arliuimte, and |ioia»iuiii 
chloride, with small quaotiiien of mdiuin uilphali', Medium ohiwphale, cal- 
cium idioHphale. and ninK"^>"ni phoq>hate:. And of fvtn tin- small <juan- 
lity of ]ih«»phati.-!i found in the aab, part of the yhfinyhunit eiialti in (he 
•erum ilnvlf, DOl as a phcitphnte, but an phiisphiiriiH in »>nu' orgfiiuic hudy. 

§ 36. The rtd torpvtctt* contain le» wiili-r limn the H-ntm. ihc amount of 
colid tnalter being variou^y Mtimat«'d m from .'iO tu -ll) or more pt^r ci-nt. 
Tho solid* arv almcjat entirely organic matter, the iiiorvnnic salt* amounting 
to lt»« than I jier cent. Of the iir^anic matter n^ain hy far the largt-r jwrt 
coneiste of ha'muglohin. In I'lO )inrT!i of ihc driH <irgnnic matter of ''~' 
corpuRclcs of human blood, about !H) jiarlii are hn-nioglnhin, about 8 part* 
proteid euhnlanccs, am) nliout '2 purls niv other (ulwlnnccs. Of (he last. 
Df the niosl important, forming about a <]uortcr of them and apparcQtljr 
being always prexeiit, is tedlliiu. Lliolesierin appears also to be nonnslly 
jimeDi. The priiicida which fi>rDi ihe sironia of the red eorpusclee ap]>e*r 
to belong chiefly to the ulnliuliji I'limily. As regards the inorganic constitu- 
ents, the corpuscles are diBlin;,-iiiabed by the relative abundance of ihe walla 
of polait-iuiu and of |>h(L^|>baii'6, This at leirnt i» the ea^ in man ; the re' 
tive i|Uiiutilies of «odium imd polaiuitim iu the corpuscle* and M-rum reo 
tivvly upgimr, however, to vary Ju dilTerent animals; in aoino the »i>d 
tnlle life in excrr* even lU llir corpuscles. 

S 37. The pioteid uialrix of the whitr rorptiiolrr we have stated t« be 
Oomp<we«l of my AMU (or an nllieil hmly >, |iiirnglohulin. and ponibly other 
proteids. The nuclei contain nueli-in. The? while onrjiiKiili-* are found to 
contain, in ndditiou to proteid material, lecithin and olher fa t», glycogen , 
eslractivcs and inorganic salts, there being in the asli, as in that of the red 
corpuscles, a preponderance of polassium sidts and of phosphates. 

The main faciN of interest then in tho chemical eompo^itioo of the blood 
arc as loliows; The red corpuisclcs consist chic tly of hu^mnglobin, I'lie organ to 
•olids of Mrum consist portly of serum-albumin, and partly of iiaraglobuliu. 
Thcitcrum or plasma man at leoM, with (lie corpuM:W. inasmuch 
n« the former contains ehii-tly ehloridw mid sodium salts, whik* the latter are 
richer in pbi^fphatcs and jioiaMiiiin suits. The extraciiveti uf the hluoil are 
reninrlcahle rather for tluir nurnl>er and variability than for iheir almndaiicc^ 
the mint coDslaot and im[Hnlaut heiiig jierhaps urea, kreatin, sugar, 
lactic ncid. 





TiiK Qt'ASTiTY or Blood. as& m jytgrRMnmov is the Body. 

, 38. T1>. 




ImImk* •tnii'k Wtni-eii (be lifsoes whirli | 
frofB. lb* bloM). Tbiis tlic [inaoe uf llic alimenUr; »iial larjii^ly luld lo tliv 
blood nier odcI tli« mmerial ilerivcd from food, ivliik- llie extri-iory Dfuiiuti 
larnly Ukc anar water itn'l the other subet«iivea ooDDlituiiu;; lli« fxc-ntioiis. 
OtMT Uaaea botli i;iTe and lake ; aw) the consUlenble dmiii fnim ihi' UI'Mid 
tv tbo l^mph sfincea wliicli takw [iliuv iu the cit[HllarM« b met by thu flow of 
lynpli intu ibe jrreat veina. 

Frun (lie mult of a tew nliierriiliuuji oti esociilcil rnmiiialH it ba.i \kkii 

candutlal tlint thu Ifital ({uaiitily of blimd in the huiuuu biHly in aWiit ii^lli 

I at iba bxily wi-ijibt. But in vnrinii.i aiiiiiinla, the prupurtinn of the weight 

I at ibe b4<mi| li> that nf the biolv iiiin lM>t-ti f»iiiid to vary vfry c<>n«idvrnbly 

io i)ifl«rriit individiiaU; and prolinbly thin holds giiod lur mim iilsti, nt all 

rmu aithin ccrtuin liniil.t. 

Id ibr uiiiip individiinl tlte <iiiiintitv prububly doca doI vary largely. A 
MMldrti dniio iijmn ihi- water of (!»■ hl<>ml by Kftnt aclivily of the eserolorv 
MCkix.a* )>j {ifKfiiwdwriUin^.Qr iinuddeii ad'Hlioii to (he niilerof thu bl<x>ii, 
M by dfinkini: large qnnntilice of wnter nr by inJcc-liDg Snid iii(» the blmxl- 
rnarla, i> ni|>idly coinpcDMtled by the pMNiige of ntiter from the liwiint to 
the hluoal, nr froin the blood to iho tiMiics. Aa we have already said, (he 
IMMn mtr ojutiiiually •trifiii^ to ki'cp up an average coni|H»)tioii of the 
MomI, anil in to Aoin^ ke«p np an average qiinntity. In starvation the <|uaD- 
lity land i|ualUy j of the bloutl b nutintained for a 1uD(; linie at the ex{>enBe 
ft Um tinuts. DO that uAer eume days' deprivation of fwid and driuk. while 
lfc« fiU. llw muaclc*. nod nlher tiiMiua have beeu largely diiuiuiihed, the ijiian- 
tity of Uood rcmaiitt nearly the tame. 

TWima] i|Hiintily or blow) preaeDi In nn animal body la eailmnted in the fol- 
InwlBg w*j : S* n\\t\i litood •» jioHible i* alluircil to mvaiic from (lie veatela ; 
tkU U Riv^urcl flir(H.-t1y. Tlie rrurU are th«n washed out with water or normal 
miixtn kJuiIixi. hii'I ibi; wailiinjt* cnrcrully c»IIe(il«iL mtxed. iind mcamred. A 
kwnra ijaaMiiy '•( blmxl U diluted nrilh wiiler ur normal Miline solution until It 
paMMMM ihc saine tint as a measured si^eciini-ii of (he washliigit. This gires the 
fg^auot ■■■ 1' ■ ■! 'nr rather of hfetnog lolling in ihe nn-axir*'! itiiecimen. Trom which 
iho tMa in llir vh'ile wuhliiKu u cnlniUtn]. l.iutlf , the whole tiixly la 

OnfWIj t- I . :iiitl nB>b«d free from bluml. The wuhiiif,'* are eollected and 
ikavad. ami the aiiii'Uiil of blood in iheni ia estliDaled. at before, by eomparlaod 
«teb a Meciaieii ni' diiiiinl bl'ioil. The ijuantity or blood, a« caleulatml from tho 
Xmn wMting*, together with the awapad aud directly ineaurod blood, giro* tlio 

I ifoafitiiy >>( biwid in ihe body. 

The »ribAd U not free frotn M>jte(loB», but other metlioda are even more Im- 

Tbr blood b in round iiuinber* dolribiited as follow* : 
Abuai niMyfourth in the heart, lungs, birgo nrtericH and vciiu. 
About one-fourth in iIk- liver. 
Aboal (mthfuurib in ihu skdeial muMk*. 
Abosi ona-fiwrlh in the other orguifl. 

^vrm in (lie heart and |;reai bloodvwoela ihfl b)owl is simply in transit, 

^•mt\ nndcrff'itnK niiy );reat (-hiuijcea (and in llio lungs, as far as we know, 

■ ! (o tt«pirali>ry rhajiiceH). il fulIowH that the allerulions whirh 

II ibe IiIoihI [iiirainK throojth the liver uimI iikelelal uiu«el(« far 

CMwed thorn arhicfa occur in tha ml ul^lh« body. 



^ 39. In otflvr tbBt (be bltiiHl may nouriiib lli« aereral ttMua* il » ■ 
lo and from thum )>v tli'^ voni'iilar iii^i'luiiiuin ; ami (hii nuriagc i*!; 
&ctiT« niovoiDciitit. 1(1 onk'r that iIk! I>U»)iI mitr (ulvqiintfly nCKircfli ihc 
sues, it tnuRt lie rcpIcniKWl by futHi from the nbniciittiry canal, and nurif 
fmru Wtc by the- rxcrclory or);uii* ', nii>) )i<itli thi-wr |mtcnM» ciilAit moi 
ni«Dt8. IIcnc« bolbrv n« jiiyicol'^I furllicr wa niuHl HUidy some of tbe geoer 
chankcilere of tho inovcRicni« of iho botly. 

M<Ml of tlie movomcule of ilie body nro cnrried out Ity mMm of tbe mi 
olra of l)i« Inink nnd lituba, whiub beiii;; connccled nilli th« flkeliHftn are 
fnH|U«otlir called skoletnl muaclee. A fikeleta) muscle wfaen subjected to 
wrlain infliienoes suddenly aborifiis. briiiffiii); its two etub nearer together ; 
and it !» tli<' Hborteuing, ai^liu;; ujiun varioris bony levers or by liotp of odier 
tueohunR-nl iirrnnKeiueuu. wliicli itntduccs the inoven»nt. i>ticli ■ triniHtnu-y 
febortciiiRg. cidb^l liirtb by iH-rtniti mfluenoe*, and due as westinll iM* to clt!uigM| 
taking |>Itic>' in the iniiNciiliir liiuiie forming the chief part of the ii)ii.'>f|i:, ^| 
technically cnllcil a foHtraidwn of tbo muxdv: and llit- niUMUiliir Imiip isfpoken 
of lu a coDtrnclilc ti»uv. Tbc hnnrt in cbittfly cMinii'isnl iif muKctibir ti«*iie. 
ditfcring in cortnin minor foittunt* fmm tin' mii»ciilur tiMuo of the Kkplciiil 
miiDcl«^, and tbe bent of the beurt is eiueniiiilly a conlmction of tbe iiiUMular 
tisiuc conirMKinK it, a .ihortenin^ of the peculiar muwular Rbm of which the 
benrt Is obiclly made up. The luuvumeiils of tlie atiinentary cannl and of 
many olbvr organs are similarly tbo results of Ihe contnu-tinn of tbe njuf- 
eular tissue entering intu lb« coraptMltion of thrise orgnno, of the iihorloning 
of certatD muscular fibre* built up into thiMC orgaiu. In fact, almml all tho 
movements of the body aro the result of the eontraetioD of muacalor fibrMt 
of various nature and variously dUp'Morl. 

Some few movements, howevor. am carried out by »tnieMir«>« which mnnoC 
Ih- called muscular. TbiiH, in the piiluionarr posfunt nixl elsewhere, more- 
lupnt b eflbcted by means of cilin atlaeliC'I to cpitheliuni cells: and else- 
where, W in the case of tlie nii;;r»ling white corpuscles i>f the bloud, Iraas- 
ftrcnec from place to place in the body is brou^^ht about by amabolfl 
mo\-ementM. But as we shall see the changes in the epithelium cell dH 
while corpuscle which are at Ihe bottom of ciliary or amiebuid moveneata 
are, in all probability, fundamentally tbe same as thow which take pinoo ' 
n mu«citlar libre wb(*n it contraoU : lliey arc of the nature of a cnnirartin 
and hence we may Npeak of all tliuie Ojt diflervnt forujti of canlrnctilr tissu^ 

Of all these variouH finon of cuntraclile liMue, the skeletal muscles, 
account of the more complete devL-lopmeiit of their functions, will l>e holt 
studied tirsl ; the others, on account of Lbeir very ninipticily, are in many 
respects les nlisfiictorily unden>t(iml, 

All the ordinary skeli>tal muxeUv nrv onnected witli nerrn. We have i 
reoaoa for thinking that they are thrown into contraetioo, under nur 
conditions, oiherwiH* ihau by the agency of nerves. ^ 

Mu»cles and iterves being thus so clowly allied, and having bcsidea M 
many nro|>ertictt in common, it will conduce to clearness and brevity if w< 
treat them logother. 

o ^_ 




TiTK piiffxoiiKirA or iidsclb avd kbrte. 




^^^V Tub- ruE:(oMe.vA of Musclb and Nemvk. 

^F Miuciilor and Jt^moHi IiTtlMiily. 

i 40. Tb« •ItolcWl uu»clet of u Trog, th« tmiii aiid spinal cord of which 
Wt* beta docnmd, do uot sxbibil tny »pi>iitanei>ii3 Diovemenu or contnu> 
llniM. CTCB thoagh lh« nervm he oihorniK iiuitv inluut. Jjifl uDdietiirbml, 
tba vboU IkmIjt mny dwomium; wiihuui auy ooalruocion of May of Um 
•kfttfjil na»cl«)i hiiving bccii witmwfil. Neither the akeletal iuuscl«e nor 
lb* nvrmt di»lrihulrd lo thpin ihhw^ss mu' powttr ul auloainLic action. 

If. hiifitiTer, ft tiiuvcic 1>« hiiil Iwiv ami he more or Ivm violently dis- 
turbed— ilT, for iiuUiiM-. il Ih- pinched, or tuuchud with ii hot wire, ur brought 
isln niDtmct nilh ivrtuin chvmicnl milietanevM, or ttuhjeclAd to the a<;tiun of 
(aK-snlr nirn>nta— il will move, thnt is. cuntrnol, whenever it b thus dis- 
torbnl. Th<Hi};h nol exhibilin^' miy epontaiieoiiA iiotivity, iho muvcle id (imd 
a«itiatw> for some time afl«r the j^oiwriil dejih of lh>: nuimiil to be) irritubU. 
Tbouffa il remaiui <)uilo lukiti-cnt whoii lell untouched, its iiDironi are then 
domBal (inly— uitt ahwiil. Thf«« require lo he routed nr "tftimulntMl" bj 
•oOM ebattge or disltirbunoe in urdt^r thai ihcy ttiny nuin!l!vt thrmselve*. 
Tb« MibtUDoe* or «|[enta which are thus, able to evoke ihc aclivily of an 
irritable miurle are ^j>i>keii of as Himuli. 

But to prtMluc* a cvnlroctiun tn a muscle the Btlmuhia n«ed not hv applied 

dinBcUr to the muiich-; il may he applied indir«ctly hjr mcnana of tbi- ner%-«, 

TblM. if lh« trunk i>f a nt^rve Ite pinched, or Mibjeclml lu xudden heat, or 

dipp^ in crrlnin cheniioal niilMtaiMes, or acted U]>->n hv various calvnniu 

canvnu. ruiitrartiuui are wen in ibe munlea lo which brancbee of tJue uervo 

aiv dtrtributcd. 

_ The iit-rvi.-, like the muscle, is irritable : it U throwp into a state of actlTity 

■ bv a ^iniulua; bul, unltkc (be muscJc, It dom not iltcif ooiilncL The 

^Kg£ni ' ' 'vs not (riv« riio in the ncrrc to any visible change of fiirm: but 

^Hb: - of M>me kind or other are Ht up and pmpagmted along th« 

^^^^re U'.'«<n to the miuclo is sliowa by the fact that the muRclc conlracU 

mUmt ■ pArt of the aent at some distance from itself is stimulated. B<Mb 

nemr and nuitole are irritablv. hul only the muBi-Ie is contractile— i.r,, raani- 

tmta ita irrir utility hr a coulractiou. The nerve maniftnls its irritability by 

itj[ [taclf, without any ri&ible alleraiiun of form, ocrtaia 

< :.'« vet up hy the stimulus. We shall cull tbeee cbaogca 

■ (has prwtwgat«il along a nerve, *' nervous impulses." 
f 41. Wt Iwe slalM ahovr thai the mii*cle ruay lie Uirown into conlrac- 
linaa by Mimnli appliitl din-ctly tu itself. Kui It miKhl fairly he nrf<tA that 
lb« nntnictioMi so pr<><lni-4Hl are in rcsility due lo the fact that tlw stiroulos, 
aliboagfa n{fparenlly applied direnlly to this muncle, in alVer all brought to 
b<ar on sunte or i>lh«ir of the many fim: nurvn-bninchtii, which as we shall 
«*« arr abiinduni in ihe mu»cle, piuvini; amung anil bc*irevn the niUHcular 
Ohw, (n which th»y fimilly end. The fdlowing facl«. however, go fsr to 
ptwc that Ihe nuscular fibres iheniM-lvcs arc capable of being directly 
«tiBOl•^ ' '*' I'i the intervention of any ncrv«s: Wlicn a frog (or other 
aninal ed with urari. the uctves may b« subjectcal to the slrongc«t 

■linali >< i::l 'Ui i.-iuihiu^ any contractions in the muscles lo which they arc 
dJtfHhutnl ; yet cvi'ii .irdinary stimdii, applieil dir*;clly to the innsclc, readily 
eonlractioni. It'. Ix-fore intr>idiicin){ the urari into the t>ystcm, a lies* 
ht- p«M«<l iin<tcn»-nth the »>-intic norve in one le^— for instance, Uie 
! Iriiwn lightly muml the wh'ile leg lo the eichision of the nerve. 
Hi- '<: thai the urari whi'n inji-clisl into the luok of the animal nill 

faia Kvsa to the Hgbl sciatic iien'e above the ligature, bul uot below, while 



it nil) huve frco accHs tu the r^st uf tlie body, includtiig llic ivlio)« 
sciatic. If, as good as the iiniri lias taken cllect, the two sciatic nervei< 
Btiraillated, uo niovemeat of llie left le;; nill be jirodiiced by ^tintulnling if 
left Bciatic, vfliereaa stront; foniractious of the luuseles nf the riybl le|f below 
the licsliire will follow eiimulHtion of the right aciattc, wlKther the uerve be 
MiiuuTiilod almve or b«luw Ihe ligature. Now, BiDce tite iip|>er parla of both 
9dati<» lire i-cjually expoeed to tlic action of the poituttj, it u dear that the 
(iiiliire of llic left nerve to cause coutrai'lion i.-< tint Httribnliilik to aiiy cbajige 
liiiTiti/ liikt^ii iiliicv t:j the iijijier purliuM of the iiltvc, eliae why Hhould uqfl 
tbr ri}{hl, whifli lins in ltd ii]ii>er [xiriion liri.*n c({UHlly rxpoicd lu the adioifl 
of thr poiiMm, aU'i fail? Kvideiilty li'e poi»iin ncl# on Mumi- |>arta of ll>e 
ncrvo loKvr dunn. If a single niiL^clv Wi removed from the t'irculatioii (by 
li^turing ilK ljliKidv*wi'lj'J, previous lo the poisoning with iirari. that wutcte 
nru) coiitJttct whc-n nny pnrt of the nerve going to it it stJmiilnti-d, ihotigh iio 
other muscle ill the Wly will contract when its nene if KtiniMliil>.il. Hi-re 
the whole nerx-e right dovni tu the muscle baa been exposed lo the action of 
the potwn. and yet it has lost none of its poner over the muscle. On the 
other hand, if tbe muscle be allowed to retuain iu the body, and su be 
exposed to tbe action of the poison, but tbe Dcrve be divided bigh up and tbe 

Jnrtcoiinccied with tbe miiscte gently lifted uji before Ihe urari is intto- 
uoed into tlie ayttem. so that no blood flown to it ami so that it is protedeit 
from the Inltnonco of the poison, stimulation of the iiLTve will be found lo 
pniduce no ciuilraetioua in Ihe muscle, though ntimuli applied ilireclly to 
the niiibclv III once cauw* it to i-oniraet. From tlicse facia it b dear that 
uniri {HiiHiofl the erdii nt tlx- nervt^ tvllhin the muiicle long before it alTects 
the trunk ; and it in cxceedinj'ly probubli; that it U the- very extreme ends of 
tbe nervcn (noRiihly the enil-|>liitra. or {Kieuliar xtriii'tnnit in which the nerve 
Hhm end in the muscular tibrcs. for urari poisoning, at least when pro- 
found, causes a slight but yet dislinclly recojijnizahlo cHect in the inicn> 
Mopic appearance of these siructures) which are aflecled. The phcuomeDii 
of uniri poboning, theretbre, go far to prove that muselea are capable of 
being made to contract by slimuli applied ilireclly Iu the muscular fibres 
lliemselvcH; and tbcrv ure other faels which support ibis view. 

$ 48. When, io a rec«nlly killeil Ihijr, we i<timulale by various means ai 
in various ways tbe uiuHcleit and nerves, it will ht: obw-rved that the mov 
mentd thus produced, though very varioun. may bo distinguUhed lo be of 
two kind*. On ihc one hand, the ri,i<uU may be n mere twitch, lu it were, 
of thii or thai mur>clc; on the »lher bitnd, one or more muscles may remain 
sliortoned or coolractci! for a ['■>ll*id^^lbU■ lime — n limb, for inslanee. being 
miscd upor stretched out. nnd kept raised up or stnMched oul fnr many 
seconds. And we lind. upon cxiiminiitiou. ihiil a stimulus may 1h- apptitu 
either in such a way as lo produce n mere Iwilch, a passing rajiid cotilro^ 
tion which is over iind gone in a fraction of a second, or in such a way lu (O 
kcci> ihe muscle shortened or conlriicted for as long a lime as, up to oertaia 
liiuils.'we may choose. The mere twitch is called a t'niyle or sim}>{K miwru|^| 
(lonlraftion : the sustained contraction, which, as we shall s«e, is really t^l 
result of rapidly re|iealed tiimple contractions, is calkvl a Manie Mntriuiitm. 

§43. [n onler to siudy ibefie contractions adeipiately, wc must hav 
recourse to the "graphic meiboil," OS it is called, aud obliiin a tracing 
other record of llic change i>f form of tlie muscle. To do thU coDvenieullj 
it is best to o|>erale with a muscle isolated fmni the n-*l nf the body of A 
recently killed animal, and ciirefully jircpurcd in >uch n way a# lo remain 
irriinbti' for some time. The niusclci' "f pold-bloodcil iininiala ronmin irri- 
table after r^innval from the Imdy far UmgtT tbnn those of warm-hl<Mi<lcd 
aniniiiU, uml hiiice those of ihe frcg iire generally made use of Wo shall 



tlitHT piwtiiilv ifir ci>n'litii>D* whicli ili'inrmim- thU mninirnamv of the iiri- 
tability uf muH-lc* ami imti'o! »(\vt n-movnl fmni thv bi.xiy, 

A ntMelf thus iMiUlt-il. with ils dctvp kft Hllsclird to it, is railed a 
m^utU'm'ryr frrpamlioH. Tlie iiK«t Cf>nvnii(iil mufcle for lliia [lUrpoee in 
Um tng t*, pn"!)*!*. iW gatlrocncmiiif^ which shoiili] be diswded uut eo ts 
lo IrsTi' rarvfiilK pnccrvnl the ntlmch merit to th« feniiir ubuve, kiiuc porlioa 
of %bt t<-nJifn I lrnil()-j\chillUl Iioliiw, and u oonudcrublt; Icufrlh ot'tbe »dalic 
mrr* kiUi iu btsiK-h«a p'iti]; lu tli« luiiad^. <Fif;. 1].) 

1^,. II. 




A MuruMitsvK l*BKr«iunuii. 
IkB ■»■>*. «w«nKa«iilUi of (K* ; ■. Ibe w4MK- nm*. «l: lli« Iinwkn Mna rui imB; exixpt 
mfftjtnf ilin n><««l< , /, Inoiir: it. riaiiip: L«-. •nnlo-AcliUlli . it-f-.t'Oiol •|ii»I niisL 

^L^SM. We may nfipiv In tut'h n niusclt^nerrv pr«psratioii the rnrioua kinds 
^■^^tali ajKik^ii III' iiliiii'r ; iiirrhiinind, mrh m iitiikii)]; or piurhing ; iher- 
^^I^Kck a* lud'li-it hcnlifi^ : i-lM-niical, rucb lU' aciil^ or ntlior wtive dwini- 
■ «ail fnWlnii(v»>. or clrctriciil ; iiii<i iIk-j* wo nmr apptv either l« the intu<cli> 

IdinTlW <ir In ihn wrvr. ihtu iitr<>>-tin^ ihv inii>cl« inOirectljr. Of nil lliew 
•Itntuli Viv fitr lb<- nimt cunvi-iiiriit l'r>r ^^eni-nit iiurpOMS are cleclrirat »uniuli 
of T«ri'iu» kind- ; mid lh«-»*. cswpl fiT (jH-cisi piiqioK*, nrc hvA appli<^ lo 
IIm Denr«, aitd n'>t •lirM-tly to tW iiiiim-1i-. 
Of «l«ctri<.'nl atiiituli, ngaiii, ihc rurrcDtn, «» they ere nlled, gCDvnitnl by 
m voltftW ovll, itrv aw^t cv>nv('niciit. lhi>U[,di ihc elorlririty gcui-mtcil bv a 
rvtBling mA);ii'-l. or Uuil iinxliieol by rrii-tiiMi mny tw tniploynl. MalciDg 
iwe of K wH <>r ImiTy of rclla— DunittirK. Gruvc'fi. l.«4'liitich£, or any olbor 
— «« mufi di*iin|;iii»li bclWMii ibe current prvduwd by lh« veil ilsolf, tbo 
eonManl rurmtl, il* «« «lmll call it, ami the iiuliu^-d nirrvjit ohlaioed fmni 
lb* conMAtit rurrrnt by m«unB of u» induction cd), u It i« colled ; fur the 
{Ajifetogit'Bl i-ilfcts of [bu two kinds of L-urrent are in many ways diDcreut. 

It naj, |>rrlia|Mi, bi> worth irLilp li> rtmind the rcxlrr uf the rollowini; facia: 
In a galtaDic battery, ihir luluiante (jilatc of lioc, lur icilaof e) iiliich U trlnl 
npno and iiwd up by the liquid ia raiird Ibe potitirt clrmeDt. anil Ibe Mibitauce 



which Ih not 10 acted ii)>oii aoiluDBd up(|)]Ht«,cic.. orco))per. pUUiiiim.or outiol 
elv.) is called tlie ntffattie olvmdnt. A gmlvnnic action in Ret Ufi wlirn tlio jKnitin 
(nine) nnil thr n«galivo (copper) eleiaonta nro conceiTitHl oubido the iMUery by 
•omfl coniluclirig material, •ucb lu a wire, and (b« curredt U aaid U flow in a cir- 
eult or circle from Ibe xIdc or poBitlvc element ta itie oojiper or negative element 
iiutdi iKe hatttnj, and then froin tlie oopmr or nwatlve element tiack to the linc 
or poailive elemool Ihroitgh Ihi^ wire ouMV^r the balirry. If the coaductiog wire 
bv cut llirnuKli. the ciirtcnt ccuscs la flow ; but If the cut enOa he brought into 
coiiLact, the current in rcf-fttablitbed aod coutiiiues to Uuw ao lui^ aa the coniai-i 
U good. The end* of ibe wirea are called " polm," or wben uaed for pliyaiological 
purpose*, Id wliich case ihoy any be fashioned in varioui wajra, are spoken of ai 
tietlroda. Wbcn the pnlm nro brouffbt inln cnntact or are connccird by fitne 
conducting lunteriul, ^ilvuoic n<:ti(in is set uii. mid the current Buwi Ibroujch (be 
bailer;^ aod wires; ihii ia spoken of at "making; ibe c(irr<!nt"or '' ciHupIetinr or 
cloaing the circuit." U'hen the poles nic (Iniwn ajmrt. from each other, or wncn 
tODie non-condurting material is ititcrposeil between thum, the Knlvaoie action u 
arrMted: thisi* npoken of a* "breakinir the current" or" opening lliecircaiL" The 
current panMa froui tJie wire cuanectea with the negative (copper) element In the 
baiterrlo the wire coitiiecledwitbthei>oritIve(Kiiiu)elGinenl in ibebaKety : hence. 
^« polocoonected with lhocopper(n<ffAtive) element is called th'-z'tMi'iV pole, and 
that coDDOCtcd with the linc (poaitive) cli'tnenl i* called the it'^iiitv pule. When 
uaed for phyaiologienl purpoiea the piuiitivc ixile betMnK-a the posiiiire rlcclrudc. 
aud the negative poltr the iieKHllre electrode. The pii^llve electrode is often 
epokeu of aa the imo<U (ann, up), and the ncgntive electrode aa the kaihtdi (kata, 

A piece of riorre of ordinary length, though not a good coodactor, ia atill ■ 
coaduclor, and when placed on the eleciroilea iMinpluioe the oircnll. permiiting 
ihc current to paai ibroUKh it; in order lo remove the nerve froiu the iullitcnce 
of the current it must beliftod oCT from the vloctrodca. Tbii is obviously inoon- 
vcnient ; and hence it is uxual to nrranfce a meana of opening nr rlooiinii; the cir* 
cult at (time puint along one of tbe two wire*. This may be done in vnrioua war* 
—by faateiiing one part of the wire into a cup of mercury, nnd >o by dippini; the 
other »art of the iriro int>> the cup to close tbe circuit anil make the' mrreot. and 
by lining it out nf tlii? mercury to open Ibe circuit anil break the current; or by 
armngiiig bctwcAu the tw'i p.irts of the wirw a movable bridge of good con- 
ducting material, aach us braitt, which can be put down to clone the circnit or 
raised up to open the circuit ; or in other ways. Such a meniu of el'Ming and 
opening a circuit, and ao of making or breaking a current, L« called a kry. 

A key whidi is frequently used by physiologiata goes by tbe name of Du B'lls- 
Reymond's key. Thouitb undtvirnbli' iu many reapects. it hiu Iho adTaniage that il 
can be used in twodiifervnt nrsT*: when arraoguaas in A. t'ig. 12, the brass hridj^e 
of K. the key, being down, and forming n nieans of good cuuduciiou bctKi-en t 
braas platea to whirn the wires are •creive<l. the circnll it closed and the cnrrc 
pasaea from thn positive pole (end of the negative (copper) element) to tbe poi 
tire elcctmde. cir anode. An., ttirougb the nerve, to Ine ntmlira eloctrode, 
kathode. K^ti.. uml thence bavk to tbe negative pole (end or tbe posi^ve (aind. 
element) in the bsttery; nn raising tbe braM bridge, the circuit i* njiciied. the 
correut broken. uikI no current passes tbrongb the electrode*. Wben arranged as in 
B. if the bnus bridge bo " down." the rosiatance oQered bv it ia so (mall, eomp.-i red 
with the reiustance ulTered by the nerve between the efectrodes, that the whole 
current from the battery pWes through the bridge back lo the battery, and none, 
or onljr an inflnitetinial p'lriinn. pawes into the nerve. When, on the irther hand, 
tbe bridge is raised, and so the conduction beiweeu tbe two sidett <<ut|fended, the 
current is not ubli> t'> pu.ii directly from one side to the other, but r^n and doee 
pM« niong tbe wire tliruuuh the nerve back lo the bntter>-. Ilvncc, in srnuige- 
meot A, potting down the key," a* il it called, nialcra ii current io the nerv«, 
and "raising" or "opening thi> key " break* the currenl. In arrangenent B, 
hou'pver, putting d':iTrn the key divorta the current from the iierv* by aendlng It 
tbrou;{h lAc bridge, aud so back tu the battery ; the current, instead of making 
the longer cin-ult througb the eleetrodw, make* tbe sh'irier circuit tbroush the 
key; hence, this is called "short'clrculting," When thi> bridge ia miscdihe cur- 
rent pMse* through the nerve on the eicctrodea. Tbns, " putting dowu " and 
"raising" or"opening" thckoy havcooatrary edect« in A and D. In B, il wlU_ 


b« afcNiTcd, ili« bnllvrr U nlirkra M work, tli« ciirtent u nlwa^H IIoitIuk tUhtt 
ikfwoith Ut« el»rtn>il«(l(er up) or through the kcylkpy donu); m A,ihel>ii«*ry 
ia tMt kt wutk ntiLil tlie otn-uii i* nude 67 [lulUnK down the ivy. And in mnny 
«M* ll U drtirablc tu take. «o in aptak. a Mmplv of ibe current while the bdtlcry 
k in (tall ■wJnif. rather tbnn Juh •» it l)«fi»« to work, Mori-ottr, in 1) tlie elec- 
llvilra Mr. libra Ibr key ii dnirn. wholly ibiit off from tlio clirrDnt; wherciw. Ill 
A, «b*n U)» k^j in up, one electrode i> •till in direct connrriion wiib the bitllery, 
•ad thh connection Icailine to what h known a* unipulnr acliim, may jtire rimi to 
■tinulaiiiiii (if iht iirrve. ilencc tbc ui«^ of Ihe key iu ibe rorm B. 

iJiliri rutin* of kvy may be uaod. Thin, in the Moivc key(r, Fi^. 13) oonlMt ia 
k Bwl* by iiraaiDE down a lever bamlle ( An) : when the prmxiro ■• remoTtHl. the 
taMfldlo, dri*eit ap by ■ (pTing, hrcnki contact. In ihe Nrrangrmrnt >liown in Ibe 
Inirv, ooa win frmn itie bsiier>' being brought to the binding *«rev 6, while tbe 
bbirdJiiit ecrew a iacoiincefol with the other wire, [laitiog down Ihe handle, tuakcn 
ecnuiecliiin belwrrn a itnd A, nnd ihuH makn a current. By nirsnuiog the wirta 
U lb* urvrnxl biixlini; *itt<vn in a ditl'rrent way, the making contact by deprtiwing 
lb* hudle may be UMd to ibort-clrcuiL 

fm. n. 

DitntAm w* tic BiA-ltrntoiitt Kty Va 
A.AaBBkla«*niltteBtU«; B, to •koiiHdKelUar 

' iniluctiun i-ull," figs. 13 and H, the wire conticctinK the two eleinctita 

Brrr is toivted at »oiuc n*n of ita course into a cloac •pira), called lllv 

primary tvu. Tbtia, ia Pig. 13. iJiv wire t'". connected with the copprr or nrga- 

Itaptelc/'.ol the hatieiT. £. Joina tbe (iriniary coil, /T.r.. aad then paiaec on 

M jT''. ihrouicb iht"\ty'" F. to the poatlive Innci plttf i./-. of the battery. 

Uref tbu primary coil. Irat tjiiite unconnected with it, •lide* aaotber coil, the 

■laa f II J oh/, 'r. : the raA* of the wire foriDiiig tbi« coil, y" and r", are con* 

tamni «a in tlie arrunKninent illuMrated in tbe li^ure aa y' and y, ukI aa x' and 

T.asfl irnninato in elect r<'itea. If thme clectr"deH are in contact or connected 

^h cosdacling matf rial, the citcuii of iho MTondary coil i* md to be clowd ; 

etltvntlea It ia open. 

In an^ an arrangetnctit it U found that at tbe loomenl when ibe primary dr- 

' nil ;• Mt.i .1 1. 1 , wbeo the jirimnry currrnt la " made," a aecoudary " induced " 

cat : t an exc«tilingly bTief |-crlod of liine, net up in tbe aecoiidary coll. 

Thi'- ,18, when, by raovine the '"key" A' y"' aoa »'"( prcriouaJy not In 

ronDf^tKiM with e^cfa other, are put iiiin cflniH-clioii, and the primary cnrremt tbaa 

■adc. at that iiMtjiiii u currrnt appear* in the nircH y". j^".etc., liut almoat imm*- 

dlMely dUappeHr*. A kiniilar nliiiosi liwiantiinroua current ia alao dereloped when 

Iba firliuary current ia " brulcen," but not till then. So long Be tbe prisiarv cur- 

mt flows Willi uniform liitenuty. no eurrcBl ia induced in tuo eeeoDdary coil. '' 

!<■ tte mrdiii rli(iiibp[«(aiMliiluglb« BiiiWlt-iH.' , ,-.:..iliMi. "ni* iiiniwlp ■, K)|i|«ttail brtlw 
clamixil.. ohlcli tinnif f'l* Ibrcnilof tt>i: flfmur/. Uoannwtad hf nmnidf ikc ^hook ■ uut a 
iluaul mlUiiiis lever I. plocol btloii ih* idqI<i cluDbtr. !>« niims. wlili ■ ynnloa ef ilw*pla*l 
oolnms K'tull uurlml bi li, ■■ iiluxl on ths •(■rtm-lMil'lat ''> i>i omUiM l•ll^ ihv win* t, v. !%• 
ntholear thelotM'.rtror tbe elm com (t. It Wpt slunM wHIi innlMKM, and ikc clRlrado-bolikT 
kiacMiKnu!i*llluu*i>lernor laaMriMil UMIIna'[«tcr mtjhi pUrfil ou ti irliiunii «Anilii( iBIa 
wnatt wiui tha Dort*. 

S. nenralTbic QtliHler bnrKti Iheiaokied p*p«"» "Olob Um lisvot wrttn. 

Clhillali-RaiiiMad'ikcTMimactdlOTibDtt-clniilllac- TIicBtRB>>i>^l>arth«tliKtn9>l»-hoU*r 

TOK MIK^'oMK^A or urAcLit and nervu. 


curirni apfican lo UM ncoirniAry vihi. f u eacu com IBe ear- 
f diirntiiin, gone io an inxtont almnat, aiij maf therefon be 
li<ji'k," Mil liitlucUon sbuvk : beine cnlled n " nuking «hook," 
<y ttir inRtinn;, and ii " brtf^kking slioiik.'' wbva it m cjUM<d b/ 


1* oalj «hfn tti4> pficDHtT current i« «ilb«- nude or brakea. or suddoolj^ rariu 
1« ialMttltj-. tliai ■ currpQi Apf««n in tint nvninAntj cM. fu each com tbe ctir- 
nal b of r»Tj britff durntin 
•p«k«n of M "■ s)igi' 
wfcia It ta c>ui«(l by 

tb bi««kin|-, of the prjinnn circuit. Th« diivclion of the ctirrcat in the making 
•bo«k b "priiiBed la tbai of ibe primary current ; tliiH. in ihe ttgute, while th« 
ptimMj rurrrnl flom from x"-' to y'", the jtidui.'i!ii miilcin); ihuck lloin from y lo 
'■ Tfc« (tirrvBt of th« bn-akio; aknek, <io the uthi!r hand. Saw* in the ume 
liirvdlMi a« tliD iiriiiiAry current frntn ^ to y. and l« therefure in direction ttaa 
re<«rw <if tb* making iJMck. Compare Pig. 14. yrbere orrangtweot i< ofaown in 
a iltefrmauBatlc manner. 

Vu.. I*. 

IRlnlia or IK iMIiirniiM Ollt. 
• fuMtn pato, «Bd of n^tflf V cteuHail ; - dwiUv* pita. Ml of imKUre e)r<iHnt of IMis.-y : K, 
Pa am Ki ) w u wr»k«yi>r. t.^t»>Ooc<l.eiirtwmM>wnbTlhH>wp*«rro«;«r t. MonuUtywU. 
nwwBi itntn bf mkiihutd am*. 

Tb* cnrrmt from 

aloof tne 

— __ o»n to a DM 

aad tbrrefim lending 

om the toUerj. U|>an lu fint i>ntrHnv« int/i the pHmnry i-oi|, m II 
h twiti -if thot coil, t'ivm rv* in tbe neb^Uboring tiriHU uf the 

10 o«l1 to m nKnuvaUrv induc^l ciirri^at hnvinj; m liifMtmi opposite lo iu own, 
to'veftken iUcir. Il UnotuuUI lltU "MlMntiucUou" Una 


■awnvi Ikmoak hIaAlnfl temn In Hw Boar nf lb* mnlM tttuntivr wltb lli* wlrai i', y', and 
aMMcand IBtMkcT.MKiHi i4ltirrM*. ItiiWuinc kfT»raklu<lxN) (lie oltMV.)'*. catnip 
— W U ^MTOBflu r. iif llM lixliii-|hKi<rnlt 1> Tl>i> •cunniltrT dill eau la nuOn la •lid* ai> 
ia*«r lb* tntmufoM f* r.. aitb vtiloli an r^nn(rii!<t ilw laawlra i" >nd ir**; ^"b 
dMcOf wlOionfolc— (cvliuuaer. lliBappn-pntcFp ctf llw ballerrX,' r*'l*e>rilt9l lo 
■■■a. «.of lhi> Mfmii tvy /*, and U roiiUuuad u yi* fium wunliv UniUna Nnw, t| of 
tha t<V M u* its* |i>la I p. lit iha taitnT' 

•4«TilMiia h- lir Bfnntnl. aa^ the hallCTr I'hariwl : em ilapmiliia Iha haadle a*, of 
tar /', a ninmi alll Iv maJg In ItH |i(lau7 will jir ( , paidiut ftum «. p Uironfft r" to 
^, «. ■adtaMoaUuiHuby" !■>«, (i-ii>ia lu ti. and lu Ihivacli »■• lu ) v iinnmoTlns the fiiiaar 
taM ** kaiHlla uf r. a Minnv tliraita ■!> Um baalk. and Hip iinuiBrv dnnii li In OMMsfQawa 

ih»l llv rAMM«y enrKoi l* cHkw hmiI* ■■hmaMi.aalnducail BUnMil la iDrike 
■wiiuyil in 111" Mnwutwy wM «. f. II iin onafclf A hi Mb Pa BitoBiTawJ^ hwt* 


rn la iWlliirk Hiu laUwlnimi, llin «!•■ c*. r*. >. iba iun« batwavn lli«al«DUDd«i 
a*(tka ali^*, ■'. ir*, IWai Uit«i>u|ilrtf<*om<lary dicult. ami (h« nnrra ooanqooiitlr *iprncii«ia 
. M Imtlnv tudatt)<Mi«boek whcm-ni ilis ivlmarr enmal I* maile or bNttm If Ika 
td ilv Im IM»-lti7»aMl ka; >• (aiit il-iA. u In Ilia dMIcd tlD« Via ik« t^m. tlw 
Hf Ibr rnivkarU n>U(l>l cionraml nllh ikaiuf IM ncnv anrtu' I ho ali«* sohig n»in 
ta* h>r *» Uw iMnc. Mat Uh) abulc accondnir (IDdocaij camni \mma iniB ^ lii v' (M Ouui y* lo 
4^ aiMB tka rus'l*'. and |«ac*l«allr b«d* |«iBi tnioUi« n«rr*. Tba nom, Wns lk«a '■•bort- 
.' u Ml adbctad lif aiij cbaafM to iW ciinaiil. 

UUilmlol lacnl/ tnUhHUaleUw (uupral inotk«ila( KiuljtOS NiiwUlarooiilnioUun : 
NN •>< 1.1 !■ MipfaadUiBiih* 'Mali* bonvtmiar* ualir«nalIradapie<l,«.iuiIaBl.ili«lisM toall 



8 used off that the current id the primary coil is eatHbliBbed in its Aiil atrengih. 
wing to tbiB delay in the full eBtublishment of the current in the primarj coil, 
the induced current in the aecondary coil ib developed more bIowIv than it would 
be were no such " self-induction " present. On the other hand, when the current 
from ihe batter; is "broken" or "abut off'' from the primary coi), no such delay 
1b ofiered to its disappearance, and consequently the induced current in the second- 
ary coil is developed with unimpeded rapidity. We shall see later on that a 
rapidly developed current is more effective as a stimulus than is a more slowly 
developed current. Hence the making shock, where rapidity of production is 
interfered with by the self-induction of the primary coil, is less effective aa a 
stimulus than the breaking shock whose development is not thus interfered with. 
The strength of the induced current depends, on the one hand, on the strength 
of the current passing through the primary coil — that is, on the strength of the 
battery. It also depends on the relative position of the two coils. Thus a second- 
ary coil ia brought nearer and nearer to the primary coil and made to overlap it 
more and more ; the induced current becomes stronger and stronger, though the 
current from tbe battery remains the same. With an ordinary battery, toe sec- 
ondary coil may be pushed to some distance away from the primary coil, and yet 
shocks sufficient to stimulate a muscle wilt be obtained. For this puipoee, how- 
ever, the two coils should be in the same line ; when the secondary coil is placed 
crosswise, at right angles to the primary, no induced current is developed, and at 
intermediate angles the induced current has intermediate strengths. 

Fill. IS, 


When the primary current is repeatedly and rapidly made and broken, the 
secondary current being developed with each make and with each break, a rapidly 
recurring series of alternating currents is developed in the secondary coil aod 
passed through its electrodes. We shall frequently speak of this aa the in/errupted 
induction current, or more briefly the interrupted current ; it is eometimes spoken 
of as the faratiic current, and the application of it to any tissue is spoken of aa 

Such a repeated breaking and mafiing of tbe primary current may be effected 
in many various ways. In the instruments commonly used for the purjiose, the 
primary current is made and broken by means of a vibrating steel slip working 
against a ningnet; hence the instrument is called a magnetic interruptor. See 

%■ '■'"'■ 
The two wires x and y from the battery are connected with the two brass pillows 

a and d by means of screws. Directly contact is thus made the current, indicated 

in the figure by the CAi'i;* interrupted line, passes in the direction of the arrows. 



mp tito pillar a. ftlang the tt(«1 •priiig h. u Ut m t]i« iwtvw e, tbe pgiot of whicb, 
um^ with plUlnuRi. I* in conUct witli ■ ooiall pluiuuaa plxte on 4. Tlie cnr- 
n«l pMMM frum 6 tbrouxh e uid « connectiaf wire into tbe prlmuy coil p. I'pou 
te MUrinf ioui ibv iirimorT coil, ui inilucM (laaUnfr) current U for tlic inaUxii 
Jwleped in tbe wcondarr coil (not ■bown iii tb* fignn). ('rom the iiriiusrT 
Mil p UW cuncni pMsee, bv a connecting wire, throueb the double tpiral m, iui<l, 
dU Kotblng happen. wmiM ciiiiinni; lo p«» frnm m ttf m coontctlng wire to the 
plUsT J, and wa by the wire y to the battery. Tie whole of Ihb eourw b imll- 
anted bj tbe thick inlrrruplcil line with its arrows. 

Pd^ W. 





Tki MaowRW bTiaatmia with IbuniMR AuuimuttyT nm KaciuoM 
twi UiKi um Unuk inn'u. 

As tbfl rurreot. h«wevrr. psnm ibrouKfa the xpirsU m, the iron cores of tli««e 
rw Mttde nugnetic TImjt In comMjoenoe draw do«m Uh iron iMr e, fixed at the 
cad of Ihv ijiring b, the Oeilbilltj of the aptiog allowiu ibi*. But wbca i i* 
dnn down, the platinum plate on the iipp«r lurTace ot fr b abo drawn awar 
ft«B tlMactew <-, and thu« the current b "uoken" at 6. (ScoBttJlMalhe screw/' 
b «> amuigwl that wlien c a drawn down a plnliiiitin tilnte on (he tmiirr lurfnoo of 
i ia beaa(bt inta oooiacc with the platiiium-ariniii [loiiii of the ikt^w/. Tbe cur* 
real ibeti riM-nt frntn A not to e bat to/, itiiil wt down tbe pillar i^, iii tbe directton 
kndicaln) by the Min iiit^rrnpted Hue, aixi out to the batlerir by the win- <r, and 
tt thot rni r.if from thi- primary coil. But ihia srrwifemetit i" unnccewiify) At 
tk' I iDt llic current in tbim broken and •» cat otT rmn ihe priiuiirr coil, 

ae ' iirenkini;) current is fur the mument developed In the ««coiidaxy coil. 

Ital Uui burteut b cut olT noi only from Ihe primary oo|]. but abo ftom the aplnb 
■■ ; In eoiHoinetice ibeir core* cease lo Im macneiized, the bu t CMiMi la be 
•nncUd bf iheoB. aod tbe aprinii/i, br Tirtueuf it* etaiticily. rwunMS Ita former 
Milllo* 111 oonbict wiib the anvn r. 'i'htt rrlurn of [he ■prini;. howerer, rcAitah- 
KAm the carrenl In the primary «>il and in tlie npimU. unit the H>rliit b drawn 
i hi ii'B, to be reltmid onoe more in ilie Mine mnnner u Wr'-re. Tbos M long m 
llw carrtnt b fwMng along ^ ibe contact of t> wiib r is sltrrnmely being made 
■■d bnkM, MM the current b comlantly paasiuK into and beinx ■hui '>ir frum />, 
llw pednds of alternation being determined by Ibe Mriodi of vibration of the 
if*{a( A. With each pa«^e oiUie curreai iuU>, or withdrawal tr«ta the primary 
<mI. an lixlueexl (msking aad. respectively, breaking) carrent is developed In a 
•eeowlar; coil. 

As thtH need, each " making iJiock." a* esplmned abora, b less powerftil than 
iW OKrvapUBdlag " brealcing »hock ;" and, indeed. It sometimes happenn that 



iiutMiI of «ac]i mtke, u well u eftcb kieiik, >eliii( u ■ •timnliu, eiTiag ri*e to ■ 
conlractloti, the "break*" onlf are eiFi^ctivc, the Hreral " luakea' gimg riw to 
BO ronlmclions. 

But what in knoirn an HelinholD:'ii armngumeDt. Fig. IC, how«ver, the makiiig 
•od breaking thocka amy be equalixed. Kor Lliis purpoM the ktcw c u niiscil out 
of reach of Uie «xcuntoiia of Uie S|iria{; t, &111] n iiiuilcraielv tblck wire v. ulfering 
A certain amounl only of rMUtance, is interposed between lue Dj)per biadine acrvir 
a' on tb« pilUr <i, and the binding kkk q' lending to the primary coil. L'ndef 
time arrariKcmooIii ibe current froin tbo battery pussM thniugfaa'.aloii^lhi? iiitvr- 
pofted wire to <•', through the primary coil uud tljus as before to m. As before by 
tlie ma^uellzation ofm.r in drawn donn and 6 brought iii ccictaci with/. Aa the 
rwult «■ lhi« cnntjiet, the currpnl from the bnilery can now im*« by m,/. mid 4 

Sbown by Ibc thin interruptt^d line] buck to ilie buttery; but not ihr whulp nf 
e current, rtunii^ uf it can «iill piuH nlong the wire w to the primury coil, the rela- 
tive amount being deiennined by the relative resistAnce ulfered by the two cuutM*. 
Hence at cnch ■ncceuivi' mnsnotiiution ofrn. the curr^'nl in ibe jirimary coil doea 
not entirely diHiippenr when t i* bruuirht in cnnlnctwith/; it is only »o far dimin- 
tfhei] Ihul 'II ceuses lo ullrftt-l c, and hence by the rcletme of 4 from / tile whole 
vurrrni uiice mure jiasHM alone to. Since, at what eorreHponds to Oie " break " 
the cuneot in the primnry coil i« diminitihod only, not abaolutely done away with, 
aelf-induclion makr« itn appearance at the " brejik " oc well a» at the "loake;" 
thoa tbe "breaking" and "nukiDg'' inducvd currentu or shocks in theaocondary 
coil are ec|uulix«i). They are both reduced lu the lower efficiency of the " mak- 
ing" aliock lu the old armiigeraent ; hence to produce the same streaglfa of «timu- 
liu wilfa thia arrHngcmenl a stronger curreni mniit be nrplicd or the *«coudaTy 
«oil poshed over the primary coil to a greater extent than with ibe olJicf arraDg«> 
men I. 

The ilienomcna oj a Simple Afutcular Oontractum. 


S 46. If the far end ot the nerre of a muscle-nerve urepnnitioii. Ftp. 1 1 
and IS. be Inid on olectrodeB cootiect^d with ilic K-cnntlnry coil of nit indue- 
tion-mAcbine, the paxsage of a nngle Induction (hock, which may he taken 
at a cnnvenient form of an almotit momentary stimnliii, will produce 110 
visible change in tlio nerve, but tbe iuu«clo will give a twitch, a «hort. sharp 
contraction, 1'. e., will for an iDilanl ■horten itaolf, boooming thicker tm 
while, and then return to ite previous condition. If one end nf llie muscle 
be nitaohed to a Ic^Tr, while the other \t lixcd, the lever will by its move- 
ments indicate the extent and duration of (he shortening. If the point of 
ilie tever be brought to bear on some rapidly travelliiig surfnoo. on which it 
leaves a tuark 1^ being for this purpose nrmod witli a ucn and ink if the sur- 
(kce lie plain paper, or with u bristle or finely pointed piece of platinum foil 
if tbe surlaoe be smoked gla^ or paiwr^ so long as tbe muscle remains ai 
rest tbe lever will describe an even line, which we may call the base lioe. 
I^ liowcver, the mascle ihorleus the lever will riae above the base line and 
thus d«tcrlbe some sort of curve above the base Hue. Now it is found tliat 
when B single inductiou-Hhoclc is sent tliruugh tlie nerve tbe twitch whidi the 
mtucle gives causea tbe lever to desoribe some such cur%'e oa that shown in 
Fig. 17; the levrr(anrra brief inltrval immediately auooeed in ^ Ihe oi>cu!ng 
or diutiiug the key, of which wi; shall apeak presently) rises at lirvt rapidly 
but nflerwnnl mnn.- niowly, stiowinu; tlmt llit- um»ele is correspond ingly 
rbortcninjf ; then ceaum to rise, showing llinl tin- muncile i* ceasing tii grow 
shorter: Uien dtvccndK, ehnwing that the nuiticlc in liMiglhening again, and 
finally, sooner or Inter, renches iiiid join* tin- baw; line, vhowing that the 
muscie utter the shortening biu regained! its prt-vioit* nuturat growlJi. 8uch 
a curve deecribcil by a muscle during a hvilch or simple iDiiScular contrao- 
tiuu, caused by a single iiiduclion -shock or by any other stimulus productng 

rne or ml'sclr axo nebvb. 


•a* «Atf,i>ctIlMl I curvAof H iqni|il« muiwdliu- oontraoioii, or, mora 
'■hvtl*. • "miuoltt-ciifvc." U b nlimiu thnt th« rsact form of (be ctirro 
dnvi^ml Uy UirM'uMl roolrncliaiu of il miiiicle will <lpp''iiil i>ii tlif rft]>ic)itv 
«kb which Oir rpcvmling surr'uw i* Irnvcllioji. Thu»if ihi- ^iirfliN be (r«v«J. 
Bm cJtiwIj ibe ii(>-ir<>ki' i^'im-^jHitiiliiig to ilic tJiitrU'tiiii^ will Iw vert' abrupt 
mad tbv ((u«i D-«ln>kv also vvrv KUtji. l<^ in Fig. 1)1, winch u n curve froia ft 





II I I <>H iirr ri«iTiiooriHii> i>r mi Pkm. Tlili cum. likv «ll mnndlnc oiis, 

iW -ti'4, i( lo iB mtd frn« kftio lUIit— ilMiltisnjr. whilpihe lentimd i«iiln(- 

• •taitiii.>r) iiic MrartiBf (OfTHv oM tmiolUns ttiHn ilEbltD InlL 

mtm Uir BoiiMti at ohttli ibr brdwiion-tluH'lt i* xuii Idu> ilu> nnr*. b Uh niiiiiiiiiiiimiiwii. 

lf»i>au uKl it Ik* rloar nf iIh OMUnffUin. 


vplrtir fune nrfcmiiuiic (benKm ouv biiiulmlili of ■ bomuL 

fencl>ralill9 iii(iarl« of n friw, tnkru vrilh a Hlowlr inuvirifr drum. tli« 
fl^lbrk b«iii^ tbe tumio ft« ibn) iind in Fig. 17 ; inilfcil, njih ii vrrv' t\ow 
wvimcnt, ihf twti mtty be hanlly •cpiimble Ham each oUht. Oh tbr olhvr 
IhumI. if the •urtiLcc irnrH verv rairidly th« curve mfty Iw iinnii»diit«lir long 
tlrmwn uat, *n in Fig. I!', whicli is » curvo from a giutrocncmiuH muscle of 
a frtifi. taketi with a very rapitlly moving pendulum monvgrnph, the tuiiiiiff- 
(oA mftrking Blwtit t'lOO vibrations a feeond. On exnniiiiHtioD, however, it 
will ho IbuQU that both these extreme curves are liindaiiicii tally the same aft 
lb* nadium one, wbea tooouat it taken of th« diSnreut rapidities of the 
ii»T«lluH surface in ibe sereral caoM. 

Ib oftfer to make ihc " mu*cle curve *' complete, il is nc>oe»arr to mark 
Ml ilw rccordii)][ surface the exiiet time at itbieb the inductian-sbock ia seut 
laut ibt aerve, and also to note the apeetl at whieh the recording etifface h 

Ib th* pendulum mvograph the rate of movenieut can be calcuUiMl from 
iK* ttogtfa of the poiiilulum: but even io this il it eouveniem, and >a the 
ea» uf the aprinfc MTu^'^ph and rerolring cylinder is neoesaarr. to roeaturc 
tba nklf of mm-enx-ni direvilv by means of a vibrating tuniug-fork, or of 
wiB« body rihiHling re^iilarfy. IndetNl it ia beet to make such a dirvct 
BManrMBMit with eai'h curve thai l- btkini. 

A taniav-fork, as i* kuown, vibrate* ao many umea a Mcond according to 
ila f>Hdb. if a inning fork, arrmil with a light murker on one uf iu prungs ' 
■M ribrating mv l"" a tccood — r. r., <is«>'uliiig a duuble vibnilion, muring 
ferwmnl and liai-kwan). 1**0 timet a second —h« brought while vibrating Iu 
■ak' a tn^-iRL' "B the recunling nirftee immcdiaiely Iwlow the lever l>c)ong- 
iap ' '. w<* (3in um: the cnrvL- or ralhiir t-urv<v di3'i'ril>o<I by the 

toD'- ' Mim thv dunition of any pari nr of tlie wholr of the miu- 

clt>e«irv«. It is i-eMnnlial thai nl *(nrliug ihr [Hiint of llie miirkcr of tba 
lastaf-fork th»u)d l>c trxnelly umli-nii-iilh ibi' marker of ihr Ivvur, ut rather, 
■nrr the fiini <>f (he lever w ii move* uii and ilnwn dtwcrilxa not a Mraieht 

but an arr 'if a circle uf which iVt fitlcruiii i» the cvOlre and ilself i,fn>m 


lli« fiilcTimi to iWtipof llie iiiai'kcri the raHiu», that llie jmiDt of the luarker 
oftho tuntng-rurk Hhoiitd be exactly mi the arc described hy the marker nflbv 
lever, either above or below it. ai may jirove mnu 
I"'"* con veil ieut. If, iheD. at MartioK the lAiDiiiR-fork 

marker be thus uii the arc of the lever marker, «iti) 
we tiuie tiu the curve of the tuning-fork the place 
ithere llie arc of the lever cula it at the Iw^iiuinv 
and at the mil of the miiscic- curve, as at Pij;. 1', 
we call cdiiiil the luimlaTof I'ihralionn of the luiiiDg- 
fi)rk which have taken place belnviMi the two niarkik 
aivl »i> niKHMiaiii the whole timu nf the inuAcle ctirvc; 
if, for inotanct-, there have I>c«-d 10 ilouhle vibration*. 
<!ac'h occupying , J^ »eci>iiil, the whi>lc curve hn» takes 
,'n so'oiti) to i»nl(e. In the Miuie nny wo Can uivKMire 
the dtirntion of ilie ri«; of tlie curw or of ibr jall, or 
of any part of it. 

Though the tuning-fork may, br »niply rtriking 
it, be set going long enough for the purpoam of an 
otwervntion, it is convenient to ke«p it going by weans 
of an electric current and a magnet, ve^- much at 
the spring in the magnetic uiterruptor (Fig- 15) is 
kept going. 

It is not ueceteary lo uee an actual tuning-fork; 
any rod. armed with a murker, which can W made to 
vibrate regularly, and whoi^e time of vibration ii 
known, may lie used for the purjxwe; lliua a reetl, 
made to vibrate by a blast of air, is tometiioee eui- 

Thv exact moment at wliich the induetioti'i>hock ii 
(brown into the nerve may be rvcoriled ou the niuicle- 
curve by menns of a " NgnnI," which may be Mjiptiiil 
in varioMi' ways, 

A light steel lever anned with n marker U arrancod 
ovM ■ Kiuiill coil by mean* of a lifibt ipriutt in Mich a 
way that when the euil by the iiiuwngc of a current 
\ through it becoum n iniignet it palls ibe lever ilown lo 
ilBcll- on Ibet-iinenl being lirolcnn.nnil the mnunetizaliuo 
of the coil ceiHinK, ibc lever by help of the *i>rioic Hie* 
lip. The marker of ouch a lever in pliiced iiniuediiti-ty 
under— i.r., at some point on the arc de«cril>ed by— ibe 
uinrker of the intisele (or other) lever. Hence by making 
a current In ilie coil and pulling tbn li^al lever down. 
nr by bicinking iin iilrcndr exi:itii>|r current, and lettinj; 
the iiidniil lever By up, we can uiake at pleaHure a mniK 
eorreiponding to any part we please of the miuclclor 
other) eari'e. 

If, in order to ningnetir« the roil of the •ignal, we tM«, 
an we may dn, the priinury current which Reuerale* the 
indurtioii-nbock. the breaking or making or the orimaij 
cnrienl. whidiever we u»ii lo proiluce the inouctino- 
■bu<^k, will make the Mgnal lever Hy up or come down. 
Bvace we ibnll huTr mi ibe recording nirface, under tli« 
niuarlr, a mark indimiiug the exact mometii at wliidi 
tlip pritiinry current was broken or made. Now the <iai« 
taken up by the generation of the induced current and ita 
M0Mge into Ibe nerve betneen the clei'triidti' i* wi inliniie*imally >maU. thai w« 
nay, without appreciable error, take the mouient of tlie breaking or making of 


tbe primary curr«DC a« the monieiit of ibe eDtr)in(«nrili« InOitclioii-ehoci: (iitutke 
nerve. Thiu wc csn mnrk Wlow ilic> niaKl«-curT«, or hy dcKribin); ih« «rc of 
tlko niMcIo lovpf, 'in ilir mumOc rurrp it«iHf. clir exact niMiieat at nliicfa the 
inducUon-sliock lalls into Ibc nervv between tbe elrclrodtn, na U dofic at a in 
RgB. 17. 18. 19. 

In the peoduluni mvogmph a «e|>arnte iiii^nal is not needed. If. harinK placed 
the mufcle tever in the pn*itinn in iThi<!h w«i intvnd to make it rm«ril. we allow 
tbpglaM pinto lo descend until Ilie tontli n' jwit toi>chei the nxl r(ta ihai the rod 
ia juiit iiltuut lo be knocked down, uud *o Ureuic tbe primary circuii) and oiake on 
tbe baite line, wblch is meannliile being dettcribed hv the lever marker, a mark to 
iitdlcnto irheie the point of tbe marker u under iliv*c drcunutancn, and then 
brinf; hnck the plate to ilK projirr pwilion, ibr mark wbidi we have made will 
mark th« muuieut nf tbe breaking of tbe primari' circuit, aud no of tbe entraiKe 
of Um ill duo I ion -9 book into the nerve. For il is juM wben. ati tbe iilaM' plaie 
airings down, tbe murker of the l«Ter comen to the mark nhicb we bare made 
that the rod f i> knocked hark and ihe primary current b broken. 

A "aixual " like ibc above, in an impr»ved form knuwn oi D«iipn^t):'s, may be 
lacd aUo Ui record liine, and ibua ibc awkwatdneM of bringing a larve tuning- 
fofk up to the recording aurracc obTiaied. For this pnrnote the signal i« intro- 
duced into fl circuit the current of nblcb ia coulinunlly ticing made and broken 
by a tuning-folk I t'ig. 21 ]. Tbe tuninu-fbrk once net ribmlini! continues to moke 
and break ibe cutreiil at e«cb of its vibrations, and ai Hinted above ia kept vibrai- 
ing by the current. Bui each make or breiik cHuwd by the ttininic-fork alTecia 
■lao tbe email roll of ibe nlgDal. causing the Icvrr of ihaaignnl u> fall down or fly 
up. Tliuii the Bignnl dcMfibea vibration curves nyncbrorioua with lho>c of the 
tuiiiD{>fu(k driving it. TbeaiKnal may similarly be worked by ineaiiiof vibrating 
^^Bta other than a tuniog-fDrk. 

Varioutt recording aurfacea may h« u»ed. The form moat generally iisefbl ia a 
cylinder covered irith imoked paper and made to revolve by clockwork or otbcr- 
wife: auch a cylinder driven by clockwork id aliown in t'ig. IS, B. ^ naiiR > 
eyiiiiderof tar^-erailiua wlthade<|uaiegeaT. a high apeetl forliiaumce, in aaeoood. 
eaa be obiaincd. In the ^Ttn;; mi/r/i/raph a amolced glaaa plate la thrust npidly 
fbrward aloog a groove by means of a spring suddenly ttirown into action. In the 

t\endiilum m-zoffrufih. Fig. 20. a amoked ^ln«> plate atlHched lo tb« lower end of a 
ong fmine avinitioi: likr a pendulum, ia auddrniy let go at a certain height, and 
so swiuga rapidtv through an am of a circle. The diuidrautxge tit tbe last two 
methods ia that the surface travels nt a contiDually ^hangiug rate, whereas, in the 
nvolving cylinder, cnreful con^iriiction and ndjuslment niill secure a very uniform 

§ 46. Htivine thus obtained a time record, and an indication ol'tlie exact 
tuoincnt at which Ihe induction -shock talis into the nerv-e, we may for preeent 
pur[KMe)t coiiiudcr tbe muscle-curve complete. The study of such a cur\-«, 
nafor inslauce that ahowu in Pig. 17, taken from ihegnUrocnctDiusof a fW)g. 
teaches u» thu follivwinK facts: 

1. Thrit nllhgii^h the piiaau^e of the indueeil current from oleciro<lc U) 
cloclrode » |inictx«illy iuKtantuncotia. iUcflcct, mwuiiirwl from I he oil trance 
of the shock into thi- nerve to the reluro of the muscle lo it« nntnrnl length 
after the sharteniiig, takn no appreciable time. In the figure, the whole 

llbeldta that pvTIlun lir Ihv lonlhu'OBlotiliutan ihr micIi v. In Ibetonnaof llaralna UielnMh 
a* ooinlfic tn coniBin wlihihct^oJeetlnaitMlrtiilf, kii<>ckiliui>unualdolmoUie|>odtlanln4loawl 
bytb« i1«ll*<l lliiv r'. Tbe nid rii In «j«trti] fuiiUnulljr villi llii> wlrv i of tbe |frtuiaiy coll of Ml 
luductlon-iiiachliiiF Tlii' (rnrw rf la ■linllarly til vli<ctrld MntlniilCT "^^ 11" o^rv yof tlMMBC |>rl> 
fuary ooU, Tlia fora^v tf aiiJ Ibc itrt i' ' rv armi-d wjili flaUnum ai ihv ]vilu<a la trhlcti tlw7 an In 
eeutuct. and bmli ai« limiUlnl liy iiil9Ui> ii{ lliv cbniilii- lilwk t X> 1iiii( a> ' anil •! am In rontacl 
UiDClrinill oT llw iitliimtrCDtl U> Hhlch i aii<l u buloiiK I* cl-awl. W lien In lu naUu (be iDuihtr* 
kuockiraua; trom it. ai tbat liuTanI tb« rtmill in broken, aiid a "lumkiue" ibuek li agiil lti|ea|li 
tin tliclniili'i uiiiiivL'ii>a Willi Uio iiBCOiu1ar7 Mil nf (tin nuirlilni>, aiul iti tlimiigb lb* atrn. Ibe 
lover r. lb* Fill) only ^•i urlilrli i<thown tn tbe dfnn-, !• brouKhi lo btarou (bcalaa plaie. and wbni 
Bimtileachbaaimliihi tlni.-, or inoTseUiOllr an on.' of a Plrelc or larito ndllK Tbo luallia-Airk/. 
Iheend«nUl]":>Illiclvn>tliDla<>ri>blcbat«abnwnlnlb*ngun|dat«dltHM0lB(«lyMOlr Dntlncr. 
Sttvea to niark tbe Ilia*, 



mrr* tnn a lad takca up alxiut tl>e tumw time u elcron iluuliti* vibrntiou 
of ibe iDotoK-fork. Siiicv Mcb doiilile viliraliou Iktc rvpRacnU lUOlh ot a 
wcwm I , U)9 diiniii<>n ol' the wbnlc i.iirvo L« ralhvr auirv iUbd I'n m.-cou(). 

2. In tlw tint pufium of ihiit period, ftnm u to b, l)i«ny b no viaible 
rfwuy. nu niiiine nf tlw levcir, »<■ ihoncnltig of th? n)u»cli'. 

T ItfenaiuDiil/'. thut i»lowy.»IWlli« lijiMof sUitit 1<lOlhM'c«n<l. tlint 
i1m> •bortftttog tx^iii- Tb» thMteninr ■» *h»wn by ihi- ourvr i* ni lirst slow, 
bat ■•-■m hccmuM mon- r«]>i<l, ami liirn I'tnckuii* sgvi'i until it fvnc)i«» a 

tsiRium atr; thsntiok- i>liiritouitig ucctipyiug rather titurv (ban f|„»eoiiul. 

ria. ». 

TW nmrM tbmi altof Ik* wlcr/mniMFIrd wllh Ihr rnliliP I - > t*>'v ''r <■)') or tW wfillt* 
. .VinritokkHay, Uinach IlKlnnlnii fl:>rt.>toini Uie|>lii ooUDMIal slih ltW(B>l->rihalair«r 
, hi lU iiMKaij la Uw «|i hf, anil to by* itlia I'liawu In ncu(v> 1ft lbs Uitdliif ten*': 
I IMa MadlBC actvir [art Of Uw viinviil Bow (limuirli ili« cnll 4 bKwcKi the pnnip ot lh» 
I tbtUM ti) ike Kin < lo ilic lilniliiiR >fit« a, whll« ■nothar pul >ovi llimiMik lli« 
I iIm colt of Iha t*et|inu ilunul burli by ibc nliv b, loUwUiuBiicicmr il Kraiu lh« 
r « Ika eutnal IMM* buk tuiii*iir|ailv*i — > |ol#orc«<lnrth«ps«lllv«al(**iui^irf 
AtUwcwmii Sinn Uifnnith ihv n(41<y ih* I>iii[iniii •icnal rrampWI^ Ike ran) (■(cull 
[^■COrtlavd ilnin40Bti Uw luiKmiribaaignal Adhcrnimni llainlbinuah IbSCcild, 
rofllMi iiill, alan IcoHiiliif mitcnellHMl. •Itainap Ibc lover immi u( lli« lirrt Dul Uw |da 
ln»M)— I fl Ihatitwdnialiiir ■i-i'ibo iimic UfU ibt fudatof Ux >4ii niiiorilic rattTiiry. Iiiroii- 
I til* oimal Mill Ibiia b(nk*a at llf, Dckiii iiritbir IbRinjfb >l tuw thfuifh ihc Imiovii 
ta w w>|i»MWf. IhefvMT of Ihr liisi«i!U thoa CHUlrii to Iv iimcnvllHil. Iti* miukti flli-* 
Mai OBMlly aa^ilvl liy*(prtD| nw* (bamiln tbe llfum But In iun**qiii>iip«i.itiliaeiirr«Dl 
[ la Id** Ikroatk 4 liio oui* oT 4 waw lo lift op itu pronit. aai) ibv iilii, in Ui* dwmni of 
t. intka OMIafl noc* stw alUi (Iw oian^rr. Tbt n^aubluhmunl nf ibc cumni. hrni- 
iaui«acUa(«a Uw two mIKaaala pull* Oma itio niukvror ibcitKnal. ainl a«iklii Xir 
■■■t>aMn«<4|«lka[>Uiv i«nna aii4 oma mon bnnkt uia aiiRwa Thiu ih« vurmt 
%t>f HNUloand UiAt*. iw niilitltrnruir imcmipUoaaMwJatcniiined bit tberlbntiiia 
> M Uw luklar'ntk. Bod ibo Ivvci •■€ iw U|[iu[ tWaf and fclUns ■nicbninuiuly uua ika 
■ «f tkaunilf«-AHk 

4. Arri^'«d at llir tnaximiim of sliortcning, llic tnuHcle at nuLv Wgin* in 
ralas. the lowr ilniiyiiiliiig al lint hIiiwIt. then molt' rapiilly, anti at liwl 
OWt* tlowly agaiD. until at J tlir niiiflr hut n^^intnl itn natural length ; 
Uw wholt rMuni from th« miLsimtiin of contrnctinn tg tho natural kiiglh 
nemiiyin); ratbrr more than jig Mcnml. 

Tbiu a Mni|>lc muMnlar conlnietion, a simple spasm or twitch, praducMl 
by ■ nonenlarT aliniuliu. such as a nnijle m<lui;lioD-»hock, cottiiMs of three 
iHMi i pliaaM ' 

1. A pboMt aiit>?oed«iit to any vuihle atteraiioD in the muscle. This 
phiwi. dariD); which ini-igibl« preparutory changes are takiug place in lb« 
atrr* taii muscle, is called the " l-iltitl periwt." 

% A [iliaso of aborteniug or, iu tbe nwre Mrtct meaning of tbe word, 

a. A phase of relasatioti or return to the orixiual I«:ii|{tb. 

In the cose we are coitftderiiij;. iht clectroijeii «n> ?u[i|>ai«<) t" lie applied 
lo tfas oerrc at soDie dbuuice th>in the laiucle. I'oiuequeDtlr the latent 



pt-rioil of ihp ciirv^' contprwcs not only the pre|iiinUorif actioiisi ip-in^ <iti in 
ihc titUDclc ilsrlf. liiil iil«o tbo cbaneM nevMHirv it' conduct lln: iitiinnliate 
eflwl of the induct! on shock from the pnrl nf ln« nerve IwIwwd the I'leo- 
trodcs itlong n cunndcrnblc length of ni.-n,'e <1«wm to tht* niii«cJr. tl in iihr(. 
ou« thiit llicef Ittltcr ehiingcs might be climinoteil hv placing the clcclrudtt 
on the muscli? iteetf or oii the nerve close to the nuisclc. If this were ilonc, 
the muscle niid lever being exactly as tiofoiv, nnd cnra were taken ihnt the 
in<luclit>n-^iock eutered into the nerve at the new epot, *l the momrnt wltcn 
the jKiiut of the lever had reached exactly the t&ioe point of the trakvelling 
fturfuce as before, two curves would be gained haviug the relation* »honn in 
Fig. 22. Tlie two curves reaenible eaon other in aTmoet all point*, except 
tliat in the curve taken with the ahorter piece of nerve, the Itilent period, 
ibii <liatance a to A a« compareil with the dtstnaoe atoh' U sliortened ; the 
coDiraetion begins rattier earlier. A Miidy nf the two curves teaches ae the 
following two fact* : 

no. -a 

0('ii\'™ ii.untinTiwi Till: MiMi-suKXT Of TiiK VtiMTrr nr * Xmrow iMrviA; 

Till! Mim tnOKle-iicrTi |icv|«mllnn IifMmuUlai ill uAirtu pcslblc trova ibo miMplt. Oiaa naai 
M lUMOile laitui muwlc: tvitbeaauaMantam K|tl*t*(vil iii*i«:tl; llicMauitn)' 

In |1> UidiliuuluiiinWnilia iienv kt Iho llatt IndlwUid by iIm Un«<i, IhcountnulloD bnrliuBib': 
Hid « IidU Uunt [ie(1iK3. UwnfUrc, la tndlcklcd 17 ihadliQuin Itoiua v> V. 

IB III ttiv •iliniiltiK niitpn Ilia nam U ulselly llin Hiino tliiiu n : tb( OnnlnwUon heflna U ft ; IhC 
lalDQI [aloil. ilivRftiir. I> liullautd bf tha illgUUM bvlimn u anil A. 

Thv Itma lakoii iiii bj' Uio iiorvmu JmtiDlH In luainR »linie ilu.- Icnttth of aem lietwwD I aiul I 
li. Ihcrvfiirc. lii'tlmtc-l tiy thv i|<«laiicr balwurs ft aiu] ft', wtili'li iiu) In mmtund h; lb* limliie-lbrb 
EiiTTo below: cmctadnablBtllinUouof ibFiunliv-mk mrmipuniliiul'lJilof ilUW8i«0MuJ. 

1. Shifting the electrod«» ftum n point nf the nerve at some distance 
IVoiH the muscle to & point of the nerve close to the muscle hiif only short- 
ened the Intent period a very little. Rron when m very long piece of nerve 
i« lakeu the iliflerence in the two curves ie very email, and, indeed, in order 
that il niny be clearly recognized or measured, the Iravellins surface raust 
be made to travel very rapidly. It is obvious, therefore, tnat by fiir the 
greater part of the latent period in taken up by changes in the miiicle iiadf, 
ehanns preiiumtory tu the actual visible ahortenink'. Of cuiirae, even when 
tbe ^otroda are placed close to tlie luusole, the latent iteriud iuchideo the 
dianeea going nii in the iihi<rt piece of nerre still K-inii biMween tbu elect nodes 
and the mu«eular fihrex. To eliuiinHte thi) with a view of determining the 
Intent period in the musiile itself, the electrodes might be placed iljrr«Uy on 
llie muscle poiMonvd niih nniri. If thix were done, it would be found tluit 
lite latent period reninined about the Nime, that is to M>y, that in all case* the 
Intent period is chieHy taken up by clinnges in the muscular w ilislinguishod 
from llie nervous element*. 

2. Hiich iliHerence as docs exist bclwc«n the two curves id the figure, 
indicates the time taken up by the propagation, along the piece of nerve, of 
the chnnge^ set up at the far end of the nerve by the induction -shock. Thcae 
chatigei we have already ^^poken of as constituting a nervous imi>ul«e : and 
ihe wTiovc ex|)ei-imeDt shows that it takes a small but yet distinctly appreci- 


Mm Un» for ■ Dervoua iinpiilBe in mvtl atoag m aurve. In tlie figure ihe 
dlflWwKW betw««n tbe two laleni iwri'Mln, the <Ii4Uinc« between b ainl h', 
MMDi «]in«t too small to ueaMiro Mcciiraivly ; btit it' a Umk piece of iierve 
tw iww) for the experiment, am) the r(>corOiiig surlacc bo made lo travel tery 
&•!. the iltfl'creDm Itclweeu the diimli'ni nl' tlw tatcnl periud viheu iW iniiuc- 
tioo^bock i* MOit ill ut a jMiiui diwv to th<^ ninecle, and that uliea it is seal 
ia At a pnni a» far aviijr a* powhlfi frotu itic muitcle. msy be wtidfavtoriljr 
■ *—w <a in fnictiou of a aocoiid. If the leagili of nerve between the two 
|>iijaBi ba accnnUtflf mcaaurtrl, thv nil« at whicb a nervous impuhe LraveU 
akmc Hk ixirva to a niii«cl<- ran tliii« Ih! easily cnlciilated. Tbii liru lie«n 
fiiuM to bv in the frug about '2'^. and in man about 33 ni«trt» |Kir micoihI, 
bat raiia* ci)D8i<k-ra)ily. csiK-ciallr in warin- blooded auiaiulA. 

Tboa when a inonteDlary stimulus, suoli ns a ftincle iiiduvti(>n-«liock, i« wnt 
iDto a Bcrve oODMit.-tetl with a muHcle, tbe folUininK <!vent:i Inkr pbu%: a 
aerroiuitnptiUeiaitsrled in the iten,'e and thin trai-ellingdowii to the muscle 
ptvdacBt in ilie hiuk'Ic:. lint the invisible cb&n^ which coiwtitulc tbu latent 
pwiod, aerondiv Ibf chanK*" which bring about Uw »horteniiig or cotilntction 
proMr.uid thirdly the changes which brin^ about the r*.-lnKatiun and rclum 
to tW original Iciii^tlt. The change* taking place in ench of these ihno 
pkaaa an change* of living mattvr ; th<;y van with the eondition of tbfi 
liTiBg anbatance of ibo ntiuclo, ami only tnke [ilncr ra long as tbe muscle is 
•liva. ThoBf[b the ralaxntion which bring* back the muwle to ita original 
length ia aamt«d by tiie muach) being loaded with a weight or oiherwiM 
Mmcbed, tbia ia not Msratial to tbe actual relaxntinn. and with the same 
load the retain will vnry according to the condition of tlie niuecle; tbe 
rcljuatian intiit be c.xi^idered as itn essential part of the whole cuotraction 
DO IcM than ihr nhorictiiui; ii^lf. 

$47. No* only, an we sliall ace later ou, dna the whole eontruction vary 
ia extant and diararter according to the rondilimi cif the mnm'Ic, thi- 
•CrtBgth tif tbe indiiction-alKick, (hi> loail whidi the muHo i» benring, and 
variottt attendant circumntanrM, but the three phaw* may varr inilepeod- 
■otly. Tlie latent period may Ih- longer or thorter, the shortening may take 
ft ItUftr i<r ahoTter time to rcaoh tbe Mine height, and espccinlly the relaxa- 
tioe aiaT be aluw nr rapid, complete or impiTfect. Etch when the same 
•Cnngth'of indaction-altock is used the oontrartton may be short and sharp 
iK Terr Xaog drawn out. ao that tbo curves described on a n^irding surface 
traTeiliDg at the same rate in tbe two c«isca appear very different; and 
tUMbr eertain <-irammanc«. as wlien a muscle is fatigued, the relaxation, 
mon peiticularly the laM part of it. may be »o slow, that it may be several 
lecqaai before tl>o tnuselc really regaina its original length. 

Hcntn ifweeay that the duration of a i-imple muHciilar contraction nf tbe 
gasUvcaemiut of a frog under onlinary cireunuitafltiea id about ^^ second, 
«f wbirh jij is taken up by (hv laivni [>eriod, f^g by the coiiirarliim, and 
yfi br the lelasalioD, those must U- takt^n as "round numli^r*," Mated so 
ae tn fce vaaily reiBembered. Thr duratinn of eacji pha.->e ti.i well ns of the 
vfcola oiiotraciion varies in diffcrrnt niiimnia, iu ditltn^nt iniiiti'Iw of the tante 
a^flMl, and in tbr same muscle und<'r ililfi-runt cnuililious. 

Thr miiK' If -curve which we have been diiw-UKiiiiit in a curve of changes 
IB Ihr Uugth onlv lit the rousclo; Uit if the mu»ote. Instead of lieing sus- 
peaded. werv laid flat I'n a glass ptatt.' aiwi a luvcr laid over it« bcllv, we 
•hould Hait, u|H>a M'ndini; an induct ion -shook into the nerve, that tlie lever 
«a* raarti, ebiiwitig that tbe muscle during the <;ontraciJon became thicker. 
Aad, if wr liMkk a graphic r«>eord of the movemente of the lever, we should 
in a cur^-o vori' aimilar tu ilte one just diacttssed ; n^r a latent |ieri<Ml 

iJm lervr wuiild rise, showing tliat the mitaek was getting thicker, and 



nftern-Hn) wciul>) fnll. vhouing that the mitsclp vrxs beoiming thiti m^silL 
In iillivr woriI>, in coiilracrioii th<' Icswiiinz ot' lh« iiitiM-lc loiigthMisc is 
ECcxrtiipniiied hv nn iriomiw croetwiw : iiideeJ. m» ire shnll eec Inlcr on. the 
muwie in ranCriicling U not ttiriiii)ieh»I in l>iilk nt all (or only lo au exceed- 
iDglv »mnll pxiciit. nbout htUif of ''« 'o^jil bulk), bnl iiiiik«e up for iu 
dimmiitinti in length by iiicreasing in its other diaiiKten. 

§4B. A single inOiictioii shock if, ne we have »aii], the roost couvenieot 
form vl' atimuTiis for proilucinK a simple luusciiUr coDiroution. but thb may 
also be obtained br other aiiniiili proriileil that these afe suffidenllv sudileii 
and short io their action, as. fur iiisunx'c. hy a priuk of, or a slurp blow oil, 
the nerve or iniuole. For the production of a aingic Moiple rauMular con* 
tmeiion the changea in the ncrvi' Itndini; Id the mu«ol« miut be of nidi ■ 
kind a» to coDstitute wlial iimr l>e cullod a kiiiglc iicrvoua impube, and any 
slituuluB nhii'b will ovoke a single ni!rv»ti:> iinpulac only may Iw uwd tu 
]in)duce a tiiinple mUK'uliir contraction. 

Aa a rule, howevur, numt stimuli, olhrr thnn lingh- indiitrtlon-thockfl, toiil 
to pnxlnce in a lurrvt; neveral ni>rvoii.« impiiUc*. and, »n we -ihall sec, the 
ucrvous impiilxo wlii'rh tmw from tin- central nerv'itiF nyeleni iin<l m> mm 
along nerrcsi l"> mu»>I(7<. arc. n' a riik-. iml Bini,'lc and simple, but. i-omplcx. 
Hence, am a mmirr of fact, n *i:iiplv niusciilnr contraction t> within the 
livEog bo<ly n conipiirntirely rnrv e\-ent (at toiut m far as the *keletiil mus- 
clw are concenicd). and cunnol easily be produced onlside the b'>dy ollver- 
wine than bv a single induction shock. The ordinsry lorm of muHciilar 
coiilraelinn is not a finiple muscular contraction, but the more complex 
form known as a teianic contmction, to tbe study of vhiob we must now 

Tehmie Contndioiu. 

-^49. If n single inductionnhock l>e fidluwed at a certain interval by a 
Swond i>hcick of the t»tnt: strength, the fir»t simple contraction will be fol- 
luued by a wecond simple coolraelioii. both contractions being separate oikI 
dutincl ; and if the «liocks be repeated n series of rhythniicallv recurrioi 
neparatv Nimple conlrai-tioiis may be obtained. If, however, the inienM 
betni-on two»hocki< be made short, if, for instatioe. it he made only just long 
emmgb to allow the tirst contraction to have passed its maximum before tbe 
Intent jwriud of the second is over, the curves of the two eontructiona «UI 
iK-dir some fwh relation to each other aa thai shown iu Vig. 23. It will Ik 


TsuiXQ or A Doi DLK Mtxrt.K-' tjiive, 
n'liUcibe miuctc (sutrocnomlut of fmKi hm ciisucnl in iIh nm saamoiloo iubwi comiM* 
<iMnr. Iiiul iiutliliit InMmnal. It liiilinUHl to Ilio diilUil Uni-i, * Hti>i»l liiilopUuii •lji>-k <rmt 
thtDOO metis tlin« Umi (Iw «K:ciud ronlractloii Iietan Jiirt w (he nm HM beRliiiilua loile- 
<lto>. T1iaTCU»idcur*cI>M*ulaaUn ftoiiillicafM.M<toa«UiefllnfWiuibeh»»»-UlM. 

observed that the second curve is almost in all reepocla like the first except 
Uial it starts, so to speak, from the linn curve iuHtejitl of from the baae-liue. 



Tbc (ceoail nerruui inipulw has acted on the already eontraclcd muacle, 
uiil Rutdo it conlrnii itKoin JuM u it would liav« dune if there had be«n no 
lint itnpulM and (lie muM-1e bad been M rcaL Tbe tnouunlraclkius «» 
•ddad tofvtber and tlie Icwr u rntHx) iiearly double tbe heigbt ii would 
bsva bmo by i-iihcr aloiic. If in the Mmv way a [bird shock follows the 
Mooad at ■ auftii-irtitlv •liort iiilirvnl, a iblnl curve U pileil on (oji uf tbe 
Mormd: t)i« laruc wilti n fntirlli, bikI to on. A more or Im* similar nwilt 
wnaU occur if tbe M^iind cunt rad inn (K'gnn nl another phaw of the tint. 
Tb* eombiiiMl t^ltct i*. of eiiiinM.'. grvat<vi whi>fl iho Mcond contmution 
WwJQi at ihi* niiixiniiitn <>f the lint, being U-it^ Ixilh befuni and anerwKrd. 

llMin-, the mull uf a r<-|H'(iti(>ii of thockx will depend lar^ly OD the 
mu of repetition. U*, as id Pig. !24, the shocks follow each oilier »o slowly 

MtKiJxTvrx. NBa< iKvecTiMi iaota lurBiTCD turnvt. 

llutonv runtrarlion i> oTor, or almost over, before lh« next liegtni, wch 
tuttractton will Iw dittincl. or ncwrly dialiiict, and tli«rv will be littlo or no 
cDBibiaed rifoct. 

If, b'lwever, th* ahucka be raiMatMl mare rapidly, lu^ in Fig. Ift, each mic* 
vediaif t^utilndiMl wi)] Mart mini aome {wrt of tlte prt'ctsliiig one, »ud llie 
Wer will l>e raised to a greater hei^fal at each contrsc^ioD. 

Miana-erati:. SaaiM, Inwcnon BMoot Rn-Miiv Ytott nirfiM.v, 

If the fre()uency of the aliocks be eiill further iacreaseil. as in Fipf. 2$, 
lit riae iluc to tbe coRibiaati'Mi of iMnlrction will be still more rapid, and a 
Waller part oi each conlnntiou will be visible on the curve. 

la cacb nf tbwe three curve» it will be itoticed thai the character of the 
nrrt dwngw •omowhat durinu; iu derelopmeoi. The change ts the nwult 
of cocatuneing fatipie, cauMid bjr the repetition of ihe contractiofin, the 
lat^aa manlfntinf; iiiielf bv aiwt inereittiii^ prulotiKation of rach ontrac- 
•bowti especinily in a delay of relaxation, and by an increaning dioii- 
in tbe height i>f tlie conlrnclion. Thun, In Fig. 24, the coninctiona 
distinct at hr^. bcc«me fu*ed hiier; the fiflh contraction, for iniilance, 
a pcoloBged to that the ilstb bvgina beforr' tJiO lever has mcbrd the ba« 
Im* : tM the *ummit of the sixth t» hardly higher than the BUininit of (he 
fifth, nace the sixth, tliuttgh itartiiig at a higher level, !■ a somewhat 
weskkrr contraction. 8ee also, in Fig, *j'i, iba lover rises mpidly at first but 



more stotvlv nllenvard, owiiij^ to iin iQcroii^ing diminution in the liviglit nf 
tli« ein>;le oontr>iclioit«. In i-'ig. '2G itie iiiL'reii]«nt ol' Hm of ihv ?iirv<' due 
to each cuutraclioo diiiiitiiahes verj* rapidly. And though the lovor does cna- 
tiDtie to ri«e during the wiinle eeries, tne oeoent ttft«r uliout ilic sixtli cm- 
traction In very t;'''i''"al itidee^l, mid the iodicntiona of tbe indiviiiuB) con- 
tractiuiia are luucb lueii marked tlian at lirst. 

Mi>''i.t<vitv& SmoLR bantctuai iuocx Rtnuicii Snix Monx RATHni-r 

Hriice, when shocks tin: rp|j*:iit(.'>l nitli sufficient raiudity, it mutta that 
alter a certain number of Hbocki, the aittcciMHliutj; iiiij)ul»e8 do not caiue hny 
lurthur shortening of the mnicli;. any further raisiof; of the leTer. but 
merely keep un tbe i-ont ruction alrcnily exixtiog. The curve thus reachea a 
maxiiiiuin, which it maintalnE, subject tf> the depressing eHects of exhaus- 
ti<Hi. «(> Icing as tJie shocks are n^pcitlcd. Wlieii these cease to be given, the 
muH'lv mtums to its natural length. 

Whun the .shocks succeed each other elill more rnpidlv tluui in Fig. 36, 
■ be individual contractions, visible at first, may become fused togttbor and 
wholly lost (o view in the latter pait of the curve, fflieo the snocks suc- 
ceed each other still more rapidly i the fecond contraction banning inltw 
ascendinfc (Kirlion nf the fintt) it becumet difficult or imnonible to ttMB 
nut any of the nngle contractions.' Tbe curve then descriWl by the tw^r 

nruc* ratamD wru Tire ohiihiibt Hwano tmaRi-ma or tn ixin'mosMucMa'a. 


TIic lnl«mi[it«l ciUTeiit U lliraw> In «l 0. 

Uof the kind ibowo in Pig. '27. where the primary current of an induction- 
machine vm rapidly made and broken by the mit^etic interruptor. Ki|{. \^. 

• Tbe <•>• nlih nhub Oir iciilivl.liul «(niinuUQM «m Ii* aMilc otii ilu|it»4t la iMn. II uwri 
Innlly boBtld.iB Ibenpwlnr '■■(■>"'■"''' "'*'""'*"*' •"•«>■» mnl. 

TUB rilKNOUENA or MI'SCLR axd nkrvk. 




TIm l«T«r. it trill bo obfm-Ml, rian nl a (ihe roeording Hirface is tntrolling 
too aluwljr to nllow th« Intent p!^ril>>) tt> ho dialin^nicbi'd), at firat very 
lapidlr, in fact iti nu unbroken bikI iilmnrt s vertical line, sinl mi v«ry 
ipffrdiW rrMtMfl tbe maxiiniim. nhich is iDttiDlJiin«d m Iod;* m the sItocM 
aoattouc Id be gircn : whva tbew- rvaso to bi' given, tbe curve <le6i-etid5 at 
fltiC nrj rmpiilTy and tben more nod more graduBlljr toward th« baK-lioc, 
«Uel) ]t mchea just at the end or ihe li^ure. 

Tb^ onxtrtion of mtiH-le, broiisbt about bj rapidly repeated aliockit, thia 
ftiaioB uf a number ul' simple tnicliea into an apparenllv unoolh coutinuout 
•Act. li knuvB aa lefamu or utaiiit eontraetutH. 'i h« afwve fteu ar« mott 
daatli' (liowQ when induct ioii-obticka, or at leaM galvanic currents id aonM 
(bfTD or <i<ber, arc enploved. Tbey are tevn, however, nbut^virr bo ihf form 
of rtiniulti* enploTMl. Tliut, in the cow of nirchaiiical Miniuli, nhilc a 
Bingtv i|aick bloit tuny eaiuie a ijngb; iwilfb, a pruiMunL-ed telanux may bo 
obuiovd by r«i>idty ntriking iiuccCMvely frtwh {mrtionii nf a uervi;. With 
rbcmieoJ Minintatinn, n.* nbcn a nrrve in dip[>e(l in noid, it a imponiibki to 
M«ra a iiionMjiitarv applicalton ; bciic« t«taDu», generally invgular in rhar- 
■cc«r. i» tbo normal n.*iilt uf thin mod* of slimufation. tn tho living body. 
tbm diHirartions of thu fkclctnl nniFcle*, bnnight aboat cither by Ihe will or 
aCbanriae, an g«D«rsUy (etanie tii vhararler. Kvcn very short sUarp raove- 
Wl at I. micb as a sud4l«n jerk of a limb or a wink of tlie eyelid, are in mlity 
ejUUBttlti of telaiiu!' of snort ditrntion. 

Ifiht fever, instead of being fastened to the tendon of a muscle hung rer- 
tleallT, be laid aenea tbe belly of » tuasole placed in a hortxonlal position 
and ihf wuscte be thrown iiilo tetanus by a rt-jwiilion of indiK-tion-shocka, it 
will be seen that each »lii)nenint; of tbe muiu'le is aocompiuiied b^ a corni- 
■pawdtpg thickening, and thai tlit? tulal shurieniiii.' ^^f 'bt- tetanus is accom* 
pntl^*^ by a r<>rrr"])"nditi^' total lliie kitting. Ami, imler^l, in lelanit* we can 
obwrrs more easily than in u Hltiglo oontraetiou that Ihe muscle in coniraet- 
htg cJuiagfa in form onlv'-not in tmlk. If a living muscte or group of 
wpaclfti be pla»<l in ■ glaaa jar or chamber, (he cIomvI lop of whivn is pro- 
IniMial into a narrow glasB lube, aud tlie chamber be filled with water (or 
plWMbly with a solution of sodium chloride, 0.6 per ocot. in strength, 
noallT eallol " normal *aliDe solution," which is kas injurious to the tiuue 
than nm|)le water) until the water rises into iIk- narrow tube, it is obvious 
tliai any change in the bulk of tbe muscle will be easily shown by a rising 
or UIIbc of tlie column of fluid in the oarraw tube. It is found that wbieu 
lb* mmole i* made to contract, even tn the most forcible manner, ihe obange 
of l*f<ri in tbe beighl of the column which con be observed is practically 
inrffiiiii am : there apfiears to be a fall indicating a diiDinnliou of bulk to 
lbo«xl«iilofal>oul»ne ten-thousandth uftlw total bulkufibemuM-le. ^hi that 
«« Btay fiiirly wiv that in a tetanus, iu>d henoe in a ximnle ountraclioii, tbe 
l^Broing iif tlii> length uf ibe muscle causes a c<>rrt?|iunding inerva>e tn tliC 
otWr rlin-<-iJoM : tbe aubstaace of ihi- muwobr in diH|ilaccd, o« diminisbad. 

f M. .Si far we liaresfMiken simply of an indiietmn-aliock orof inductfen- 
■bnaks withool any referencv t» their Mnmgth, and of a living or irritablu 
moscU viihoui any reference to the degree or extent of it* irritjtbility. But 
indvcti'ia-shaeks may vary in i4rcngt£, and tlm irritability of the niuxcle 
nsr Tarr. 

if «T slide tbe secondary cnil a long way from iIh^ primary* coil, and thus 
anke use of extremely feoule induct ion-shiicks. we shall probably Hnd that 
iteBabocka, applieil even to a <)Liilc fn?>h miuch- nerve preparation, produce 
SO oMtlraottoo. If ne then gradually *lide the K-conoary coil twarer and 
SSWar the primary coil, ami keep un trying the etfecis of tbe shocks, we fhall 
i»d tbit kftar a'while, in a certain position of the coils, a very feeble ooo- 



IrHctioii nmkiw iu sppcaranoe. As the tocondary coil comn still nnrar to 
iitv [irimary coil, the coutniCtiotiH gmw grenlcr anil greater. AD«r n wliilo, 
however — nml that, indeed, in onlinnr}' circiiiniitiiiiri^, vcrv ipccdilv — incroms- 
injf rha^ntreiigthof the*Iii)ck no loiiu^r ini.TniuN.w thu height >rf Lht: roninidion ; 
the msxiniuni contnu-linii of which the iniiwle u cnpahlo with «ucb shocks, 
Imwcvct strong, hiw Ih-wi rwiohcl. 

If wc 080 a tetiuiixing or interrupted cnrn'nl, we ehall ohtjiin ihe same 
gcnernl results: wo Ria)-, nccnn)ii>g la the stnmglh of the current, get no 
eoNtrmcli'on at nil. or cuntrncttoRfi >.'( vnrioue extent up to a maximum, which 
eiiunot be exceeded. Under fnvomble eonditiaii» the maximum ooniractiun 
niny be very considerable: the shortening in tetanus may amouiit to three- 
fifths of the total length of the muscle. 

The amount of coDtmctiou, then, depends on the strength of the Mimului, 
whatever be Ihe stimulus: but this holds good wiili in certain liinilaooly; 
lo this poiDl, however, we shall return later on. 

S 91. If, having ascerlaioed in a wrtectly freeh luueele-nerve pre|«rnLiun 
the amount of c;nlrai:tiiiu produced by this aud thnt eitreuglh of »iimulu«, 
ire leave tlie preparation by itself for some time — auy for a few hount — and 
then repeat the observitliuus. we shall Sud that stronger stimuli — atrongor 
^flcks, for intttanee — an> reijuired l» produce the «iue iinmunt of cnnlractiiu 
lift before; that in to tiay, tlie irritability of tlie preiiuretiou, the power to 
respond to stimuli, hti^i in the meanwhile d i nil iii shed. Af^r a lurthor 
iDlorvaJ we sliould find the iTritabilily still fnrlbrr diminishv<l : even very 
strong shocks would he unable tu uvgke ci>T>travliiini> lU' large n* thoet- pre- 
Tinush- caused by w«ik shocks. At laat we ■■■hoiild lind that no shocks, no 
stimuli, however strong, were able to produce any visible oonlrnction what- 
ever. The amount of •■ontriiriiuii. in fuel, evoked by a stimulus depends not 
only on the Atren^th of the stimulus, but also on the degree of irritability of 
Uie musclu-Dorve preparation. 

Imniediiitely upon removal from the body, Ihe preparation po a w noca • 
certain amount of irrilabilily, not ditTerin^ very materially from that which 
the muscle nml nerve puuewM while witbm mid formioK an int(!(cral [Jitrt of 
the body; but after removal fn)m the body the preparation loaeairritabilily, 
the rale' of lorn bein^ dep)-iidcnt ud ii variety of cin-umatanoea; and thixgotw 
on until, since no stimulus which wi- can apply will give liae to a oontraC' 
tion. we say the irriuibilily bus wholly dinappctAred. 

We might lake this diiappcaranoe of irrittibility bh marking the death of 
the preparation, but it is followed aocmer or later by it curimi:! change iu the 
luuBcle, nhich is called rigor mortis, and which wr 4iall Mudy pnveiilly : and 
it is convenient to regard this rigor morti." iw niarkinu; thu death of the muscle. 

Tbe irntable muscle, then, when slimuUlcd eitlicr directly, the stimulus 
Mail aiipliixl to itself, or indirectly, the slirauhi:> being applied lo iis nerve, 
reapond» to the elimulus bv n change of form which in i,«w,-Jilinlly a shorten- 
ing and tliiekening. By the »horU;ntng (mid ihickiiiiiig) the muscle in oon- 
trndiiig i* able to do work, to move the |uiri« to which it is attached ; it thus 
tol* free energy. We have now lo study more in detail how this energy 
i^ set fn-e, and the laws which regulate it« oxpvnditure. 



B The Cbanffe in Form. ^H 

^fiS- Tfie yrat* tirveUirf of mimrtc. An nrdinart' skeletal iniiscle onn- 
nsta of e/onenturjr muKUjibret, bouod together in variously arranged bttodles 



.acctive tMue wliicli carria bli>odT««el>, avrves, ■itd 1]rmphatie& [Fig. 

The Min« cMiDcdlve timoe, IwvhIm Aipjilyin^ u mora ur tcM ilistinot 

tiffiaf fctr Uw wboU mutclc. Toraut thr two ■■tiili ol' the iiiiieclc. Iteing Iters 

(mn KUltv. lu «l>ef« tliv miitK-lc iipix-im lo be iJirectly nltached to R 
Imoc^ aai % •null amuutit oiilr ot wnncctivo titwic joins th« niusoulitr fibrae 
to tbr iicri'ii4<-uni, M>tnetiiii(4 nliuiidimt, us when tli« cunnoctive tissue in 
whkh tor muvnilnr tilinv imiiHilintrlr end is prolonged iuUi a tendiMi. 

EmIi flkaiCDlarjr fibre, nhich viim« ev«it in the lunnimiit in li-nL-tb and 
brMkdtb (ta ibt tng iW dimrn; ions vnry rcry iri^tely <, but may he «aid, on an 
Avcngt, lo be 30 or 40 mm, in length and 'iOu to 30" in breailtb, coosieU of 
•a ifiiitic botnogtDMiu^ or fnintl}- librilhiied «Ii«aili of peculiar nature, the 
m rt » h m m a. which embrmcn »nd lurms on enrelufX! fur thi: ttriaUd miu- 

'jr m^antf tiiihin. [Fig. 29.] Each fibre, cj'lindrical in form, giving a 

rin. Ifc 

. MmoM rwiii Till nnutn-HMTOtD im Han (mapiUWil M ilmMi u. tiWi- 
•■I tMtatfitan: hlMalcDhn; r. iiiwtnal pmmr^ami d.Mn. 
nk. w — Fuajoan or fttRmir KitMartmy Pibmw. tiitdrDM i Clurivt n orMiran DnacnoM 
I «■ aiMBHcrx. 

Itlamcr. Ttao Uwcltodlntl aiiAitiianvnennMaKhiitfaMvii. Aotnc lansitndtnal 
r anil *klrt ihkii tin nM, u>4 an out aHMImunD IMin end to *n>L Tliln naiilu Itom 
■ of tlwMtlllr. caWllaMfonMfrcanncaBMlisrbr TlotonMiltlMtookSiinUl 
.■Mlnwkad tgtimmwwtlla«»crmt||inrlilt>iotlnncoBUieatrp:t'<* m i i i jwi Hwo 
■ nnmwntf inminwl brtha MfaimioddiifleaMllv mwnMsbly nucniiMj: at r* iba 
I inBmam Iiiimm* all pntVdlx ncnitanf. •'•'I ll>r mrlUilFd tfaicn ivrMilr nMaiifo- 
bar M ■* llw konlcn m ^aUiifsd am] the tfiaaii Inail-Iitr. Wbcii mon (Ilnlatl and deDiillp. 
am Ha W fc tW BM llw fc«»it ut Ihao app^ mn eai. 

•lai«W& Tka Imgllndlaal llnoi an tnmilj TWbl* s. inconiplrtr ftutor* bHOB- 

niDuatf • 4Ih) wlilch •(>«•<*<• aCTCB Ibe lMer«a> and (ttaini the tnvfniniHmJl 

TW>d|*«>4*utibc»iif tUa diM an •*•« tu t* ■iuuMl)' jmnulu. tte inaaiih* 

laflnitir tiitli»iiilckM«<>rtk«dlMaAd tn ibr dMaaov Mratvn Uw Mhi laatHuilliial 

■tM bomIt •StiiibDl : y. ilttaclMil AIM. mut* bifklj tnacnlacd. alioaliw lh« 



or laM circular outliiK in iransverw aection, ^nerally taper* oS at each 
^d in a cunJeal fonn. 

Ai oub «n<l of ihtt fibre the mroolemma. to which in life the muscular 
■abMuKV i* lullimnl, bvoomea continuouH with fibrilUe of connective tissue. 
Whao Uw «tul of lliv fibre li«« ni the end of the muacle, these conntwlive- 
^mam fihrilln |Maa directly intii the tendon (or into the ueiiaateuin, etc.) and 
ia (nat* CBMB of uniill muvctui which are no longer tnun their conatitueut 
Ana, CMcIt fibre may ihui join at <«cfa end uf iLMlf. by means of its aareo- 
Jmmos. the t«Dd>in, ur other ending of the muMle. In a verr large number 
«f ■iitlw. b»wovcr, the niuM-Ie >• liir lunger than any of iiH fibres, and there 
m^ be «Ten whole twndica of tibrca io lue middle uf tW muscle which do 




DOt renc^ to either cud. In such com the ominective tinuc in wtiich tbt 
t»n!o\emma ends is L''.>ntii)UouR with ihc couiicctive Iimuo which, niiiRin^ 
l>etweci) the fibres mid between the I>uiid]e8. hinds ihe fibm intu email 
biiudles. aiid the !»Jitaller Iniixllcs intu ]ar)^r buiidlca. 

Tlie conlraetioo of a riiusele is the c-uutracliciii of all or eome of il» 
cknieiilury librea. the timneelive liiaue Wiuu paaiive; heoce while thoee 
fihrta of the iiiuttcle which end direetly iti the tetidoii. in coutraeiiu); pull 
directly on the teudon, ihuoe which do Dot ho ciid |iuU iiitllreetlT on the teudoo 
bv nMuini> of tbe cunnei-live liwue between the bundles, wbicb connective 
tfariie ia <^AUtiiiuoui« with the teiidou. 

Th« bloodv«aseli run in the coiin«ctivtt tiwue hotwet-n the buodlee and 
bctw«cii the Gbres.aiid Ihe capillariM form mori; or K«> rectangular networks 
i mined lately outside ilie narcoleitinin. [Fig. 30.] Lympbaiic vc«els al>» run 
iu the coDne(.'ii\'(.- ti»iui\ id llio lymjih tipncv? of which they bcE'i- Kacli 
iiiufcularlihre isthu»Kiirrounde'l by lymjih fpnt-c* and capilliirj' bti>odvca«eU. 
but tlw active uuiBriilar MutNitancc of the Irbre is »(<paralG>d from the*C by ibe 
uroolemnia; hi-in-*- ibe interchange between the blood and tlie CDUKiilar 
8ubaUui€« a i-arrieil on backward and forward througti the cajiillary wall, 
tbrou|rii aomo >>t' tho Irninh gpacea. and through the earcoletnina. 

Each luusclv i» «iiiiphcd by one or more branches of ner\'e# ronipowd of 
luedullalod fibres, with n certain proportion of n(m-iiiedullate<l Hbm. Time 
branehos running in tbe ci^nneoiive ttEsue divide into Bnmller branehea and 
IwigB between tbcbuniUesaiid fibres. S.i[iie of the nerve fibres are dislributMl 
Ki tlte bloodvcKels. and otherv end iu a manner of which we shall s|)eak later 
t>n in lrealin<; of muscular ^nBatimid; but by fur the greater pan of tbe 
iiiedullaled fibres end in the muHeuhir tihrRt, llicnrraiigement being such that 
every muscular fibre is ;uppli(h] with ut least one niedullat«d nerve fibre, 

which joins the niuHculnr fibre somewltere abotit 
the middle between Its ttro ends or winietimei 
nearer one end, in a special norve ending, of 
which we shall pi'eseiitly havo to e]>cak, called 
an fit'l-p/ate. [Hr. 31. J Tbe norvc lihn"» thua 
ii<-»tinei:l lo end iu the niUHColar fibre? divide 
as they enter the luujcle, so that what, as U 
enters tbe luusole, i« a single nerve fibre, may, 

in.., «. 


I MiM-LE, ^juicn. mini moaiuK or Ooul 

CIIA>*fllI8 IK A XL'SCLK l>l'lll>'0 roNTRAl'TION. 



by (IWiilingi. end iu> »cv«nil ucrve fibrcB In MrenI musctilnr llttrt^. SntiietiiDM 
twoDarwlibttt j<^iaoii« tnu»citlnr ftbre. line in thin caw (lio i>iiiI-i>1bi« of c«rh 
tiem ^br« i* •Ull lU totao duiunri' rniiu lht> end of lh« tiiunciiliir fibre. It 
Mknn tb»i wtiCD ■ mtiMulMr fibre i> MimulAtiHl by nioiiiu nC n nnrvc tibrc, 
Um DfTVow imputw tnNfllin^ ilon-n lh« ii«n-« fibiv fulU inln ihc iiiii«c>ilftr 
Sbra Oflt It MM rD<) but Hi nlioiit ibi mitbllp; ii Ik tin: ^tilltlK^ of llii' fibri> 
which it mitbeui firet by the ncrvout iinpiiW, anil l)ir i-lninKiv in tl>u muwTuUr 
mImum* lUrUd in the nii<t<)l(? of tlu' miuciilnr Hbri;. Irnvt') ih«Dc« to th« tvro 
«iKlt of tfao fibfo. In an onlinary ekckitil nitieck. h»w«rcr, tm wt have Mi<t, 
th« flbrw ami Imiidlm of libm Wgiu and end al dilTiTcnit di»Iiinc» from l)i« 
tads of tb*> mu«clt>, and the nerve or ncfvr» gnin]; to ibc mi»ol<> dividv itnd 
»pwd oat in th« mii6clt> in sucb a way ibat rlie end-(>lat«a, in which tb« 
ntdividoal fibrea of the nen-e end, are distributed wideir over the rium-I)? nt 
van* tHflbrail diataacw (hini the endp of the miifcle. Hpnoe, if we iiippuao 
• '(m}e nervooB impulse. Mich ae thnt eeserated by a tinjjle induction -shock, 
or KMrkaofsucb impulsei* to lie started at the ^nie time at sonic nnrt of the 
■rank of the iMrve in «ich of i)i« fibres of the nerve ^'oinj* to tne muscle, 
the« impulMa irill mu-b rery diflerait ports ofthe muscle ai about the same 
line uia tbe eontrai-ttons u'bi<^h Ihey set >r<iin|; will bcf^ to speak, nearly 
all oTar the whole uniMk at ihv oiime time, iiud will not all stan in any par- 
liealar tone or area of ti»e muscle. 

f SS. 7%r •I'liw of eonlraetion. We have leeD, however, that under lh« 
iaBlMPca of uniri th« nervi? fibre i^i iin:ilile to excite cnntmctiona in a mu*- 
rsUr flbre, altlmugb iIk irrilahilily iif ibv muicular fibre itmlf i« retained. 
Hmmm in tt miucla poiwned by timri the contmotion bl^^^« nt that |uirl of 
tbe BiMDnUr Mbaunce which io finit ntlvctcd by the Mimulns, and vrt inay 
•urt a tininnion in what |>nrt of the mutvlc we (ilouc by properly placinjr 
lb* plirirodea. 

Attar niinclea,aovh for inetaooe as the •nrforiiM of ihefras, thouf^h of some 
ijctfa, an compneed of fibres which run parallel lo each other tVom one end 
ibr miucle to the other. If such a muscle be poisoned with uraii so as to 
If the action of the nervce and itimulaied iii one end (an iuducliou- 
Atk vui ibroufib a pair of electrotlM placed at some little dblaoce a|Mn 
tnm each uiber at the end of tbeuiUM^le may lieempluyed.biit betior remlia 
■rwobuIneH if a mo<le of mimulaiion. of which we shall have to Mx-ak jirm- 
cntlr, vtL thr application of the " cunstani current," Iw Bdo]>t«il), lh«- con* 
inctinn which emueaHartit from ilwondnlimulaled, ami Inivcis ih«nco along 
lb* BiMcle^ If two lever* tn; m»d<.' t<i rc«ton,or be su^^jirnded fnim.lwi [Mirta 
nf Mch ft tORDcl* plac«d horijiiinlally, the pnrla being at n known dialancc 
fwvn* iind iVoni the part (timnlatcd, iheprwgrewof the conimctioa 

BMlr U in 

The noreiDcnl* of ihr li^%'cr* indimtu in thui cn,-«i> lh<- thickcnio)! of tho 
flfana which U takini; place ut the juiri* '•» which Ihi- lever* nvi or to which 
ibey an attached; aiid if we take n graphic record oJ' ihme movements, 
briegfaif the Iwo h>ver! to mark, one immi-diately below the other, we Khali 
felt that the kver near«r the part «(imulatcd hegiiw to mo^-e earlier, rnachea 
lu amimura rarlier. and return* lo n^t earlier than dric« the further lever, 
TIn nAlraction. started by the ctimnlus. in travelling nhing the oiuacle from 
iba pari iiimnlated raaohea the nearer lever some little lime before it reaches 
the (briber lever, aud has passed by the nearer lever some littto lime Iwfore 
t( baa fauaed bv the further lever; ami the fnrther apart the Iwo levers are 
I In Miaali I will Iw th^-diNVrence in time between their movements. In oiher 

wiinU, thv ' ti iraveU aloiij; ihe muscle in the form of n wave, each 

jmn uf tbi II. succmnon from the end Blitnuluteil swelling; out and 

ibartaniog aa the contraelioo reacbea it, and then reiuniioK to ils oripnnl 



atnlo. And nhat in true of the oJlectiini of iiHratli>l fil>ron nhich vn- cnll tl 
RHiwlc U alio Irii6 uf ciu'h fibrv. tar tin* s»Flliiij; ut iiiiy [ictrt uf tin- inusole if 
ooly the ftiim af thi^ •wolUii); ol' lli<; iinltviiluiil &\in» ; aiKl if irv wera aUv to 
uk« n Hiiigle long fibrv nml MiniiiliUi' it itt one vml. we »hoiilil be nble, 
iindrr tlif mierwcopc, lo ««MniwrIling or bulging ncciimpnniitl bv» eniTfr- 
■pnn<)iiig»liorlciiiiig, I. r, toMu n con traction, «vrccpuluiig (hetibre fronj end 
to end. 

If, !n (he graphic rccnnl of the two icvtn jiiM mentioned, wo count tbe 
Dumber of ribmlione of llie tuning-fork which iDlcrreiie Wtwecn the mark 
on tho record which iudicatce the ttcginning of the rise of the near lever 
FthBtis.lh«nrrivHl of the contraction wni'cnt lhi« lever) and the lunrk which 
indicaim the Wftinniiig of ihc ru« of the tar lever, thia will give ub the tiuie 
which it has tnken the coutraclian w.tve lo trtivel from the near to the fttr 
lever. Let uh suppoM? lhi»io he 0.006 wcoiid. Let iia euppose the dttitanve 
between llie two levers to he lo mm. The coiiiraclion w»ve. then, hn* taken 
0.006 wcdnd to travel lo mm., that is to sia.v it has travelled at the rate of 3 
oieirM per tti-ruud. And indeed we liiid l\r thia. or hy otlier loethodn, ttiat in the 
frog'* muHeteD the cuutractiou wave dues travel at a rale which may Iv put 
down Hf from '-i tn 4 nietrai u second, thmixh ii varie« umlrr 'litfcn'iu mndi* 
tioHH. In ihr wiirni-hliiiHhxl nmmiiml the rate b aonewhat greiiter, nnd majr 
pnilmhl y l>e put down tit 5 roetrcii a iccntid iu the exdaed miiH'lc, rising poe- 
*ibly to 10 niein:'? in x nuivcle within the living body. 

If, ognin, in thu graphic recoril of the two leven we couni, in th* esse of 
cither l«ver, the number of vibrittiona of the tuning-fork trhieb intervene 
betwe«n the mark where the lever liegin« to rise an<l the murk where it ha* 
finished ilH fnll nml returnni to the ba»e-line, we onii menxitre the time inter- 
vening between the contraction wave rr-aching the la\'er and Icnving tbo lever 
on its way onward, Ihikt is to say wc on mi-asurv the time which it hB« taken 
the contraction wave to para over the part of tbe muiicle on which the Ivrer 
is rwting. Let ua aupjHHe this time to be, say, 0.1 Eccond. But a wave which 
iit travelling at the rate of 3 metres a eecond and takes 0.1 docuiiiI to paw 
over anv |<oint muhl lie 300 mm. long. And. indet^^l, we find that in the 
trva the length uf the couti-action wave may be ]>ui down as varying froni 
200 li> -too mm., ami in the mnmnial it h not very dillWent. 

Now, a* wf have naid, thL> very longt«l luiisciilar tlbre U Jttatei) to br at 
Bi«iet •inly about 40 mm. in li^ngth ; hence, in an ordinary cmniraction. during 
the gmiter part of the durutiou of the contraction the wbolo IflUgih »f the 
Gbra will be occupied liy the eoti tract ion wave. Just at the bo^nlug of tlie 
contraction then- will be n time when the front of the contrwitiOD wave haa 
reached for instance only halfway down the libra leuppoting tbe stlmuhiG to 
be ap(died, as in the caae we have licen diaeuBring. at one oad only J, and jiiat 
at toe end of (be contraction there fill l>e a lime, fjr instance, when the »>ii- 
traelJou hna lell the half of the Hhro nest to theatimuUia, but haa nnl ret 
cleared away from tho other half. But neartv all the rest of the time every 
(lart of the fibre will l)o in some phaae or other of contraotion, though the 

fioriit nearer the stimulus will be in more advanced phaae* Ihan the part* 
iirlher from tlie stimulus. 

This b true wheu n muacle of parallel fibras is ntiniulaled artificially at 
one end of the muscles, and when, therefore, each libri; i^ Htimulaiisl at one 
eaul. It ia, of course, all the mure true wheu a muacle of urdluaiy coo* 
■tnictiou b «timu1ate<l by tueaun of its nerve. Tbe Hiululu^ of tli« nervouf 
inipulMr impingM. in Ihia caae, on the niii:>ch' lihn; at the cnd-plat« which, a* 
we have aaid, in placed toward the miildli.- of lh<- tibrc, and the contraction 
wave traveli from the end-plate tu opposite direction)' lowunt encli end, and 
bw accordingly only ahuui half the Ivngih of the librr to run iu. Ail the 



mure thnntot*. must the whale fibre \» io a state of coulractioii at the wnae 

It will be ohecn-e<l tliat in whni has juet beeti said tlie oonlraclion wave 
tarn b(m lakeD lo include not <ml>' the onlrnetioo proper, ttie ihiokeDing 
MkI •borteniii)t, but also the reUxnlioD und return tu the DatuntI form; ibe 
Ar>l [Hirl of tlie nave up tu the suiuiuit of the creel comnKHuU to tb« 
■ li-'rtruitii; nnd itiickinio);. the decline from llie siiiuiuit ouirard CorKe[Kin<k 
bi Ihe rvlaxaiiiin. But we have nlrendy iDBiHUHl that tbe relaxolion is an 
— aatial part of iho nhulc^act; inde«(l, in a certain ^eoae, aseaeentia) ait the 
•hurttnlDk: il*cir. 

I M. JUiiiuir ttnitinrt of mutevtar fibrt. 60 far we have beeo dealiug 
m\ilk (b« miiwie a> a wbol« and ai obM.T\'eil with tiie naked eye, though we 
ban itKtdeoialljr 'IKikeD of fibre*. W« have noo', confining our Htteniiou 
csdaiiTely to tikcli-tal niuw:]i.'ii. lu coibud«r nhat tiiicr«ACo|>ic changut lukt^ 
placv doriDK a contraction, what arv tbc rulatioua uf Ihe hirtulogicut feature* 
■if tba muK'iv fibre Ui tbe act of eouumction. 

Tba liHiK cylindrical fbcnth of snrcolomma t* nccupicd by niiiMit sub<tancc. 
AfUr ilMkUi lIm: iiiiitlc nultFinncc may M^pnr.ite from tbc Knrcolcmnia, U-4iving 
lb« Wucr as a distinct 'lifAlh, liul during lite iho muscloaulwUnce is adhervnt 
tM 1^ iknvdrninia, h< that no line of iicpnnUion belwcMi tlit- two can l>e 
■uub oat ; thu niovenients of tin.- one follow exactly all Ui« movement* of Ibe 
other. , 

.■<^lt-m) in the rniiM.-le snbslHDce. but, in the mamma), lyiii^ for the moi>t 
pan rfnf<^ imiU'r iIh- ■^nnsilt'oiDin. are n nunilicr ofniirtei, oral in sha|ie. witb 
iImi' ites parallel to the length of the fibre. Around each uuclein is 

a ii< 1 i>f KrMnular-Iooking suDManee very similar in appesran<'e t<i that 

faraBMrUw iKxIy of a white biood-corpn^cle, nnd like that oftCD spoken of 
as tnuAnnilaiod prolophiain. A shmII i|imiitity of cite hbdm stmnular imb- 
Ksam u pml'iuji^il fur iMime ilixtniicc lU a narrow coui<'jil Mreak from oach 
ta\ of ih>? noclcii*. alon^f the lcn;j;th of the fibrv. 

With the csixplion of tbtM nuclei with tW-ir grauulnr looking bol and 
4* end -plate ••r i;nd-nlalc8. toW precvntlv dvccrilx^, all thereat ortbe»|iaG« 
tpfliwail by iIk- snrculetnma fiMU on« en<f of (he (ibrc to lliv other apficara to 
b eompinl bv u {Hvuliar rnnlerial, lirialtd muWr /mtulaiiec. 

It m cnlluJ Hrialett hccaiife it is marknl out, ami that along tlio whole 
laqph of Ihe Sbrv, by transvene liandc [Pig. 3:!], stretchiiig right acrom the 

[Plu XL 


Di«i«t.icNjiTR RxraaoT^raw or jt Hcaoia^uR. 
■Mil— 1« f rlwii, BB«<Wli<of>l>«»»*li"<*'M«l»roJi! tfc Anld «Wuw«.I 

ftiV, nf aubMance which is very Irait^parenl, hriyhl »abiUiHef, altcmaling 
•itb Mrailar bands of substance which has a dim cloudy appearnncv, dim 
aiMcnw; llial b to any the 6bre ia marked out alonp^ iu Wliole length by 
ttUnMn brifhl baml* and 'lim h'lndt. Tlie briglil bands are on an average 
about \ por !■•> » and the dini bands about 2.6 « or ^i •> thick. Bv care- 
hi toattiiam, both bright bandi ami dim b«niis may be traoed tlirough 
tha wkJa laickiMM of tin: fibre, .io (hat the wrbolo fibre appears to be com- 
pMd of bdskt disc* muI dim Aae* placed alternately one upon ihe other 
ala^ i1m whole length of tlie fibrv, tbc amingGiuent being brviken by ilie 


• 'k «kw>iti '(l)iv » trvaled with dilute mineral acids it a very apt 

. ,. ..|- iMu.ic>n(;I> iucvdiiM-s [Fig. 3'2], the sarcolemma being diaaolvM, 

■ ■iv.Mi ■& juruiv c\> divide into fragments corresponding to the dines ; 

. :r4 ud,_<> .iiiiR. b< obtxinet] ao thin as to comprise oaly a single dim or 

■ „.:. >H.iM, 'i-tJiru twuu) with a thin layer of bright substance above aod 

\ ■.. I, ,\m •■iiMtHipf having taicen place along the middle of the bright 

«t 'K-> '«uKt\.>i «iih tvrtain reagents, alcohol, chromic acid, etc., the fibre 

■ >,.< if'. I" ^'U\. M)* i.aiid the splitting up may be assisted by " teasing") 
-. .„.!•.. iiiiikl.k luivi ivliiiuits of variable thickness, some of which however 
..-v v vv4\luij;ly thin, and are then sometimes spoken of as " fibrillK." .iv'H' ^(ini.'ti Hiid tibritlte are artificial products, the results of a trans- 
...^ >i k-u^itkidinal cleavage of the dead, hardened, or otherwise prepared 
u.i-Aiv lutvitMUtv. 'I'hev may moreover be obtained in almost any tbicknea 
1 i-iiiiiuvw. Aitd thvw tliscs and fibrillfe do not by themselves prove much 
>, >>gi.t iht- iWt thai t\w libre tends to cleave in the two directions. 

Ihv lis Ills lilirt> hiiwfver, though at times quite glassy looking, the bright 
\.>i.U ft|>t«-Mi'i»K likti trans^tarent glass and the dim bands like ground glass, 
'• ti othvi iiim*> marked with longitudinal lines giving rise to a longitudinal 
..•i.tti^'ii. H<u»>l iiiim iHiDspicuous and occasionally' obscuring the transverse 
A'MLUti III lht< iiuim'Im of some insects each dim band has a distinct p&li> 
..t.'v' •t|>)>t>HiMii<H> an if made up of a number ot " fibrille " or " rods " placed 
.i>lv t>t ■»!>' ami iiiibtilded in some material of a different nature ; moreover 
>k.H' iDiiillii' or nidd may, with greater difficulty, be traced through the 
ixi^Ki bit I >d 4, and lliitt at times along the whole length of the fibre. And 
ili.'U' ii H ijivat dt-al of evidence, into which we cannot enter here, which 
i^oix li> I'li'Vt' lliitl in alt striated muscle, mammalian muscle included, the 
iiiMv U< iiitwtHiiiv \» nmlly composed of longitudinally placed natural ^ArtVAs 
.'I n iviiaiii iiHlum, imtVddeil in an interfibrillar suDstance of a ditferait 
ii.tititv III iiiiiiuniHlian nuisoloand vertebrate muscle generally these fibril lie 
iiu iMiviiingly tiiiii and in most cases are not sharply defined by optical 
ilniitu'tKia iVotii ihi'ir intertibrillar bed; in insect muscles and some other 
iiiiiti \vm ihcv am rt-lalivt'ly large, well defined, and conspicuous. The artifi- 
k'Kil iiliitll(*< uliliiini'il bv iciwiiig may perhaps in some cases where they are 
I \i>'i'iliii>tly iliin I'lun'HiMind to these natural fibrillse, but in the majority of 
uiii'H ihov t'ci'tidnly di> not. 

Ill it'i'liiiii iiiaiH-l iiinMcUi< each bright band has in it two (or sometimes 
iiiuiio iliiik liiiM which are granular in appearance and may be resolved by 
.idi'>|iiiiiii iiiiignitViiig (HiwiT into rows of granules. Since they may bv focQs- 
ui;' lii> liiii'i'd lliviuigh tl)e whole thickness of the fibre the lines are the 
I t)iii'si)iiiii i>r liiiH'H. l''rfi|U('i)tly the tinea in the bright bands are bo conepic- 
ilkU' 111 li' riinii'iliuti< a givaler share to the transverse striation of the fiore 
lliiiii iln lilt' dim IiiiiiiIh. Similar granular lines (rows or rather discs of 
Kiiuiuli>.->i uiiiy uiiio bo Hccii, though less distinctly, in vertebrate, including 
iiiiiiiiiiiidiiiii, iiiiiHi'li'. 

Il<niili<ii iliiviK griiniitnr liiici> whose position in the bright band is near to 
I ill I Inn liaiiili, nHcn tipjicnriiig to form, as it were, the upper edge of the dim 
l-iiiiil liiliiH iiiid tlm lowiT cilgc of the dim band above, there may be also 
n..iii,ununlrHfrd aunt her Iransverae thin line in the very middle of the bright 
luiiid. 'I'hix lint', like Ihit other lines (or bands), is the expression of a disc 
and liiiB liiTii ludd by wmw observers to represent a membrane stretched 
iiii.i-w lim nliiili> ihickncHii of the fibre and adherent at the circumference 
Hilli llm BHiriilniiiiiii ; ill this sense it is spoken of as Krame'i nwinbraiie. 
Till' iriiMuiiB I'm Inlioving that the line really represents a definite membrane 



tM>t however ap(i«ar to he adeiiiiate. 
metliiitc line." 

Wli«n ■ itiiii trniuvftrM secUon of frnxcii muM'lc n cxaminetl quile IVo>U 
Hod'T u tii^h pi>w(!r, tlin iini.-u-lf Kutuiniici- within the Huvoltoima ia wcu tp 
ba niurlcil oul into n uutulxr '>f umiill motv or lew polygon nl Area*. AD d it 
aitDilar nmtiif(<:nH-nt iuto nntu miiy al«i> bo Mwn in tmitsvunM.- xn^tion* of 
prefwrad inuNcIc, though lh<- iVtiturrs of the nrcif orp somcnhat liillvrout 
from thorn mod in thoi fmli living libre. Thcw areas are B|x>ki>a of M 
" Cohnheim'fl nrfm* ;" they ano vcn- much larg«i: than the dinawtcr of a 
RKrilla as iodicatMl bv t}i« ioniiituiUDal etrialion, and indoed corrupond to 
a whole hundle of suoh tibrilla>. Their exwlence teeaa to iodicnte tnat the 
ftbriUje are arrao^'ed in lort);itiiilinal prisiiia separated from each oliter hr a 
larser nniount of iiiterhbrillar subitaiice than tbtU uniting to^'ether the tndi- 
ridual libriliw formin}; each priam. 

LiMtiy i( way be mentiun«(l that not only are the various Kranular linet 
»1 times visible with diliiculiv or iiuite invbible. but that even the diAtino- 
tinn belReeu dim and bright band» in uccAsii>iinily very faint or olwcure, the 
whoh- muiii:i<^ »u balance. n|>art from the iiudei. apftearing almoet huiuoKetieouk, 

Withuui attemi>tinx to diwuw the many and varioui inlerpretatioiia of ihu 
■Imvv flixl ithtir lUtaila conoerninfc the minute vtmctiire of striated musctilar 
(ibr(>. n<> may here oiHilvfit outsvlvM with the following general conclusion*: 

(1,1 That ihv am»ch ituliKtiuicc i* t^ompiMed of longitudinally di«po«ed 
Jibriltir I priilNttily (■ylindricat in general form an<l itrolMbly arrangcil in 
h>OK>ludinn) pri'inii) rm)>r(td<)d in an inlrrfi/irlllar notiaaee, whi<'h ap|H-iir« 
111 Fh- Inw ililWentiatfil thiin th^t lihriltic ihemaclvci and which i« probably 
cfintinuoita with the undiircreii[>at«<t protoplmm round tin- nuclei. Thv 
iiitcrtibriUnr fubrtaooe etains morv raidily with n^ld rhloridv than do the 
fibriliir, and hrnce in gotd chloride epodmcM appear a* a rort of mcsliaork, 
wilb hingitudinal i-paoet^ correHpondlng to th« fihrillffi. 

(2i That the inierlibrillar Bubolancc w, relatively to tlie fihrilljB, more 
abuntlaoi in the musclei of some animale than iu thow of others, heiug for 
instaiioe very roiispicuoua in lli« nitiHcles of insects, in whicii animals we 
■bnuld naturally expect the leas ditferentiaied material to be more plentiful 
than til the muscles of the more highly developed mammal. 

('■H That ihe Gbrillie and interSbrillar substance baviuK dilferent refcac* 
live jHiwerv, some of the optical featurea of muscle may t>e due. on the one 
haira til the relative proportion of tibHII» to incerfihrillar «ubsiance, and on 
tlie other IuuhI to tine librillie not beint: cylindrical throujthout the length 
nf tin' tilire hut contitHcted at intcnaU, and thus l>ecoming headed or 
OKMiditortu ; for iiwtancifl the roiva of granules xi><>kuii ufabovi- arc by lunnc 
rtpu-<lrd 111 carrM|H>»ilini[ to aggregation* of mtertibrillar maliTial lilliiig 
lip the r|iar>-« where ihr fihrilhe arc nu«l coitttrinted. But it dow not Mem 
pLMihln at the prTMenl time to make any ftalenivnt which nill mtbfoctorily 
explain all lb« varioUN appoaraiicew met with. 

t AB. We may now rettim to the •lutvlion. What happen* when a conlruc- 
lioD wnv Nwiyip* over Ihe fibre? 

MuMTular fibre* may be examined oven un<ler high power* of the raicro- 
«CQp« while they are yet living and contractile: the oonlraclion tiself may 
U (cen, biit the rate at which the wave travels u too rapid to [>crmit Katis- 
faclury observations being made a§ to the minute changix' which accompany 
cotilraclton. It fre<jueiitly happens however that when living muBCle 
l>cen treated with certain reagents, as for instance with otimic aeid vupor, 
•ubpe<]i>ently prepareil for examination, fibres are found in which a 
ig, a tbickeniitit and shortetiing, over a greater or leee part of the length 



of the Abre, has been Bxed by ihe oemtc acM or olber iVAgeiit. Such b 
bulginK ubvioiuly difl^ra ttom a normal ountrectioti in being conffoeil to a 
pnrt ov Ihe lotifili of ilie fibre, v.')i«rea«, aa we ha\-(- nuiil, a normal wavo of 
contrutioD, btiDg v«ry inii<^)i longer ibaii any fibre, •>ccur>iM t)i« uIkiIc 
loi^t4i of tbe fibrfl at once. W« mar Iiuwrvcr n-)^nl lhi« bulgtiii; w a vi-n- 
slwit. a very abbr«viiit<<(l wnv<- »f riiotriK-rion, unil nwuine lb»i th«' t'lian^ 
visiblo in sucb a short bulging iiU» tiiki.- jilitcv in n normal contmciioii. 

Admitting ibis avuinpUon. wc learn fr»m siicb prepanttions tbal in the 
cunlrnciing region of the fibre, while lioth dim nnd bright banda become 
braaderncroea lh« fibr«, nnd correspondingly thinner nlong tlw Icnglh of tbe 
fibre, B remarkable change takee place hetwe«n the dim bands, brignt haDda, 
and granular lin««. We have seen ibat in Ihe fibre at rest the inter mediate 
line in ibe bright baud t< in moM casea iucuDspicuoui ; in tlie contracting 
fibre, on (h« contrary, a dark lin« in the middle of the bright band in tbe 
ptieiiioD of the intermediate line becomee very distinct. As we ]mum along 
tbe libre Irom (be beginning of tbe coiitrartion wave (o the summit of the 
wave, where the thickening ia great4»t, thi>t line beooinftt more ami more 
•tri king, until at the height of the contrai'tion it beoomes a rerv marked 
dark line or thin itnrk band. Pari fintm with thid changr, th<r diMinctioo 
between t)iv dim nn'l bri;;lil liiuiiln become leHs and Irm Jiiarked ; thne 
aitjuMir to bcoi>mc ciinfii#c<l Ingiaher, until nt th<; hi^ight of the oontraclioR, 
the whole space between esich tivo now cnnxpiciioti'' dark linw is occupied by 
a •iib<4nnc« which can be called neither dim nor bright, but which m con- 
triMt to the dark line apjHtars more or hw bright and transparent. So thai 
in lll« contracting part there is, at the height of the contraction, n rev^ntal 
of the state of things proper to the part at rest. The place occupietl bv Tlif 
bright baud, in the state of rest, is now largely tilled by a conspicuoiiH dark 
line which previously was represented by llw inconspicuous mlermediale 
line, and the place occtipiiii by the eon^picuous dim band of the llbre at roM 
now Mcm* bv ooinpnriMon with the dark line tbe brighter pan of iIk- fibre. 
Th« contracting fibre ts, like tbe fibre at reit, striated, but its striaiion is dif> 
Ibrent in icii natur« fr^xn the natural striaiion of tlte railing fibre ; and it is 
hdd bv wHue that in the earlier phii»i=« of the contraction, white the old natu- 
ral itruition is being replaced by the new uriation, there m a alagv in wbldi 
all striaiion is lest. 

We may add that the outline of the sarcolcm ma, which in the fibre at rest 
is quite even, becomes during the contraction indented opposite the interme- 
diate line, and bulges out in the interval l^tween flach two ioteroiedbita 
lines, the bulging and indentation becoming more narked the gmUr tb* 
con tract ion. 

§ 96. We can learn something further about this remarkable cbangn by 
examining the fibre under polariiHMl light. 

Wli«ii urdinary light U aetil tliruu^h h XIcoI prism (which is a rhoinb i>r [ne- 
laud «psr divided Inlo two in a cerlflin directloa, the faalrei being Mib»i>i)ueriily 
oemeated U^thor Jn a special way) it undergoes a ebange la jMsaing through tbe 
prism and is said to bo polarhrH. One e(^t of this |>oUriallon ia that a ray 
of light which bus pn»ed through one Nicol prism will or will not pMS tfaroucb a 
semoil Nicol Hcconllng to the ri-lallv«' jiusltion of thu (»<• iinKinn. Than, if the 
second Nicol be so placed that what i« cnl1c<! ii« '' optic ai'is ' b« in a line with or 
psrallel to the optic nxii' of the Hnt Nicol the light passing through the II rot Nlcul 
will also (MUD through tbe Kccond. Etui if ihc second Nicol W roMl«d until its 
<^e axb ia at right angles with tbe optic axis or the fint Nicol wiat of tii« light 
]>aMlRglhruugbthefom>erwillpaMthrough the latter; iheprisuis in this posliioo 
ar« ssld to be " crossed," In intermediate posilioDs more or Ic-m light paaiiea 
ihriugb the sccoixt Nicol according to tbe nngle bsfweon the two optic nxm. 

ileiHM) when one Nicol is placed beiwath the stage of a microMOpe mi tlmt tbe 


U Irom th^ mirnif in t^iit tliroui'li it. hiiJ aiintlier Ntcol is plitoed in tli« «y«- 
, r«. tlir tiriil of Ihi- inii;m(ico(i«i i*ill ap)i««r ilnrb «b«n th« ey^-pieee Niool ia 
nitktfld »•> tliHi iu optic iixia i« kt Hghl Anglm to the i>|tlic ftxii of thr lower Xicol, 
Mi'l coiM«<iuent1y tht? light pawing throusii (ho l<iw«r Nicol in •Ii>|i|)e<l by it. ir, 
buwrvrr. tli« "plic axi" <if the t'_v<'-ii!ccc Nico] iH piirallfrl toikuturilie tower Nicol. 
ilio liichl from thr Intirr will [.ftKi ihrouEh the hnaet am) the Held will be bright: 
lUKlaa tbvcTv-piMie m srMluntty roiaief fVoiit oiiepmition tn theolkM tb« brlgbt< 
ncM of ilie i!l«)d will tlunioioh nr increMe. 

Botli ilie Niool« ar* «>RipoMHl of ihiubly rofrnctlve niuterinl. If now a ihlrd 
iImiIi])- trfrHciive aial«ri«t lie pUcoil mi Ibe vtuge. aiitl tlierefore between ihe two 
Nirol*. [he liicht pMai up through ihe loirer Nicol will (in a certain poaitiixi «f the 
ilonbly refriLiivc mntenal on the xtaee, that is to aay. whcii itn optic *xm hava a 
i-rnain r'niiion} paai ihningh it, ana alxi through the rrairej Nieol iu the eye- 
(liece. ilencc tbe doubly refraclivr mntrrial on the Hlage (or -tioh [iflrtH of It aa 
ar>' i" ff'i- irfnper poaition in rwjiew to iheir oplic axw) will, when the eye-piece 
Ni -ed. nmiMf llliiiuinale'] ami bright on a ilnrk field. In thin way the 

et I - I iluubl; ivfraeiire malorial in a prepiuatiiiii may be iletcclvd. 

When tnu»cle [ireparecl nnd n>04int«<) En Catioiia bttlaum u exatained in 
th« microecupt! Iwtweeii Nioo) jinanii'. oik uii tbe vUiK^ helow lh« •.ibjoul, and 
tbe (itber iu the i'v(:-|>i«<x-, t])« Hbrm stand unl iw bnght objvctn on Ibi; <lHrk 
DDtl of III*' li<^ld when llut axes of tbe |>riKtna nn; cnNwed. On cUmrf 
linatioa it L« nvco that the parts whieh iin- )>n^lil urv chi«flj thv dim 
m. Thia Indii-nlea that it is the dim iMiidit which arc dmibly n-frH«tivc, 
iMtrfrD/fM-, or an- ehii-fiT made up of anisotropic subatnnce; tluire sc«rii». 
eter, to be iu>nie slight nmouQt of nniaotropic subaUan in tbe bright 
ada, thiiueb thot: lis a whole appear single refntelivo or itolropic. The 
tibn iceonliDKly apjwars banded or rtrialod with alternate bnnds of nniao- 
tnipic noi) iaotropie materia). According to most auihore such nn alterna- 
tiiiD (if anisotropic and (chiefly) iaotropic bands which is obvious in a dead 
■mi preiMred fibre exists also in ihe living fibre ; but some maintain thai the 
iviOK filire in uniformly aubotr<ipie. 

~~"ow, when a fibre raulracta,in »])iteol"the confunion preriAiMlj mentioned 
reodini and bri^hi Iwodx, there i» no eouftiKiou between liie anisotnipio 
nd iantrapic materia). The ani»otr»iiie. duubly refmetive bands, bright 
under crm»ed Nicxtli, tMieuprin): tlie poititiou of the dim ban<ta in tbe resting 
Rbrr, remain iloul))}' refract ive.liright tindiTr croiaed Nicu)s, ev«D at the very 
of the eontmclioii. Th«isotr<i|>ic. Kiiigly refractive )>andi'. darlc under 
' Nicolii, iKiciipyiiig thft pavition of the l>riu;hl bandi> in the fibre at rest, 
iaotropic and dark uiiderenj*«i^l NicoU ni tlie very height of the 
txHUradlon. A)l tliiit cnn )>vMen is that the singly refruciiveisotro)tic btinda 
bevome ver^- thin indeed during Ihe cu lit mot ion, while the nni»oln)pic tiandM, 
tbough of contw becoming thinner mid bronder in the coutriKriion, ilo not 
mc- so thin U do the i<<>tropic bands : in other vrontf, while liolh )>ikuiU 
me ihinDvr and broader, tne donbty refractive iini>^olr(ipic band si,-«nis 
norcMse at tbe expense of the singly refractive isi^ronic liitnd. 
$ 07. We ea)l attention to these tads because they »how him- complex ifl 
the a<-t «f contraction. The mere broadening and shortening of i-aeh seetton 
of ihv fibre is at bollom, a translocation of the molecules of the muscle siih< 
tUQon. If we imagine a company of 100 soldiers ten nuiks deU|>, with ten 
mHi b Meli rank, rapidly, but by a series of grnilutions. to ext«n(l out into 
a diinble line with oO men in each line, we ^hall have a rouffh image of tho 
iBDV^mcnl iif the nmleeulea during a muscular coiitrvdion. But, from what 
Ilia tiM-n Milil. it is obvioun Ihni the movement, in striateil mnsele at least, is 
a very nimplicntMt on<> ; in uilii^r forms of contractile tiMiie it may be, as we 
■ball «<•, more "imple. Why the movement ii so complicated in striated 
nu*clv, wbal purpumi it eerven, why the nkek-ul musetn* are titrialed, we do 



ont *t |»mcni kimw. A|i|Mir«Dtlv wlu^rc Nwift and nii>id oontnifiiitii it 
requintl iho coiitraciili- iiMtio in Mnutol inuMtk ; but how Ute Mriatioii hvlim. 
•0 to )t|K9ik, th<: ciiiil tiirltiiu vri- <)<> not kniiw. We l'hiiikiL nay vrhnt Khiiro in 
lh« net of coDtrnctivn i.* t» bo ttlliaCol U> lh« ocvrrul juarta. .Sincr. during 
K cuuUmi^ion, the fibro hkilgaw out awrv 0|>|x)»it« to cficli dim di>c. nnd 
\b indented opposite to c«ck bright disc, «inc« tliv ilini di>c i« mora largely 
(vxDpoced of anisotropic mau-rial than the rwt of tbo fibre, and siooe Uk 
anisotropic nutl«rtnl in the |x>sition of the dim disc iiicmiMa' <liiring a cod- 
triK-iiou. nc might porhajw infer tUiit the dim disc mthor than tlic brij^bt 
disc is lh« eneDtially active rmrt. Awiimini^ thiit lh« fibrillar substaDcc is 
more abundaut in tlie dim discs, while the micrlihrillar substance ta more 
abundant iu th« bright discs, and that the fibrillar substance is anisotropic 
(and hence ilie dim discs larKcIv nuUotrupic), while th« inicilibritlar sub- 
stance is isotropio, ne mifht also be inclined to iufer it is the 6brillar and 
nol (be iuterfibrillar subetauoe which reallir carries out the coutractiou ; but 
even tliia much iu ni>t yet definitely jiroved. 

One tliiu^ mujit !>« remembered. The muscle substance, though it p<j»- 
»vsii-i the ouiujiliculed ttnicture, and t^M through the remarkabUr channi 
whirh We have <lt-»cnb«l, \a while it h uviag and intact in a condition which 
wc are dnvc.ii to t\teak of ux nemi-Htiid. Tlie whole of itU ewcnliiilly miJtlle. 
T)u> very act of coutmi-liiui indin-d nhowsthb; but it in nmttik in the sciisic that 
no part of it, except of counw the nuclei ami itarccilcmma, neither dim nor 
l>rif(ht futwtanee, neither fibrillar nor iut«rfibrillur nulMiaiicv. «ui tw regarded 
a* a hard nnd fimt structure. A minute ueniatoid wonn has been scon wan- 
<lvnng in the nmlst of tlie substance of n living contrnctiletibrc: wi it moved 
along, tlvo muscle stibelanec gave way iH-fore it, ami closed upii«ain bebiud it, 
dim band)' and bright bauds all falling back into their proper pMuva. We may 
suppoM that in this case the norm Itircnded its way in a lluid intertibrillar 
suoshioce between and anmiig highly extensible and clastic 6bri)l(e. But 
even on auch a view, and .ilill more on liie view that the tibrillar aub^tance 
also U'u broken and clooecl u» agwn, (he maintenance ot such definite hii<to- 
Iflgical fbatures oa (hoee whicn we have deeeribed in malarial ao mobile can 
Mily be eflibcted, even in the Hbre at reel, at some conudenible exiwodttitre 
ofener^: which energy it may be expected hasa cJieniical muroe. During 
the contraction tliciv ia a Mill ftirtber expenditure of ejier(,'y, mm*> of which, 
as we have seen, may l«avo the muacle aa *' work dune ;" thh energy-, lik^ 
wise, may Im* cxpeclc<l to have a chemical aouroe. We miisi, tbcivfore. now 
luni to the cliumistry of miiade. 

T/if Cftmintry 0/ Mwrft. 

$ 98. We said in the Introduction that it was difficult to make out with 
certainty the exact chemical ditferencee between dead and living nub- 
ittance. Muscle, however, in dying undergoes a remarkable ebemical change, 
uliii-h may be studied with comiiaratire ease. We have alrvatly niA that 
all miucl», within a certain time aAer removal from th« body, or. if still 
n'nniining jiarl of tlie boily, within a certain time after "geocral" death of 
lh«' Wly, l«*e their irrituhiliiy, and that the lose of irritability, which, even 
when rapid, t« gradual, in {•uccedlcl by an event which io Mmcwhat more 
sodden, vir_, ihv entrance into tho condition known as riyor inorlU. The 
oocurreiice of rigor mortis, or cadaveric rigidity, lu it is sometimes caiile<d, 
which may be ci>i)«idercd im the token of tbo death of the muscle, is marked 
by the following features: The living muscle pooaassas a certain Iranslucency. 
the rigid muscle n distinctly more opaque. The living muscle is very exten- 
sible and elastic, it siretchee readily and to a oooaiaerabto esleni when a 

VBTeDsUnT The entrance into rigor nortb », 

' ft dtoneniug or coiitractiuu, which inaj, un<ter oe: 

liderable. The energv of thU (vintractinu In t»n ^rent, fu> tlint any 
iboricaingiseui)y|)rt!veui«(l by the |irt!Miiii.-vi>l'eTeiiui'li^ht ^pjiwing 

the cWuiral fviiluKu of th« t\md r^id inuwlc art idso Mrikiiigly dif' 
rotii ihm^ «>' thn living tuiiiKitv. 

^n lifid miijWi-, fnim which itll flit, uihIod. fnsciH, and oonoectivo 
He btruiu much lu (xi^ihio n^niovm). <>i)d which hiu bMfi Awod from 
^ho iiijrctiuii of " normnl " siiline solution, be ini»M-<l nnd n-])aitcdlT 

with wntcr, the wnshin^ will coiiuiD corlaiii furnis of nUiiiiiiiii nnd 
«xlniclit'« IxMJies.of which ««■ sbsll apoalt directly, Wtieii ihe wiish- 
■ been continue'l uniil the wesb>waier Kires no proteid reaction, a 
IWtion of muscle will Mill remain nudiaeolved. If (IiiB be trenled with 
roenl. Aoluiion uf a neutral saH, aminonium chlonde betiiK 'be heal, 

portion of it will Itecome dissolved ; llie mduiion. liowever. la iDOre or 
perfect and 5Iten with dilficulty. If the filtrate be alloired to fall 
y dn>]> into a Isr^rc ijuauiitv t>f ilintillnl witter, a while flucculeiit 
will be {irecipilat*^!. Tlii.i ifoivuleni prvcifiitale ia myiMiii. MyoaJn 
KrH), (living the oritinnry jioiU'id ri-itctionn. un<l haviii^ the turne geU' 
liunttnry <'>itN|<naili(in mi other pr<>tci<li>. Il in ixilulilio in dilute MiliDft 
m, aqHioiallv IbixK of ammouiuni chloride, and niav' Im i:1bm>c-<1 in (he 
I fiiinily, cltmigh i( is not so soluble as {laraglouulin, requiring a 
r mtuUitii of a neutral •all to diiaolve it ; (htis. while soluble in a A 
nr n>tH. soluti^m of such a sail, it is far leas soluble in a 1 per mnt. 
I, which, ns we have seen, readily dissolves parsglobulin. From its 
IS in ueuintl saline solution it is precipitated by saturatioD with n 

snlt, jtreferably sodium chloride, and may be purified by being 

with a saturated solution, dt»olved a^cain in a weaker solution, and 
jitaied by saturBtion. Dinotved in saline solutions it readily cua^;- 
wtteti heate<t — i.e,, U couvert^sl into eoajjulaled proteid — and it is 

■if tiotiee (bat it coafculute? ai a comparatively low temperature, vi^., 
6° C. ; thiM it will Im remembered is ihe temperature at which Hbrin- 

congulnletl, wliere** pwraglnbulin, senim-albumin. and many otber 
I dii not (VM^iliite until a higher tcm|H-rHture, 7'>° C, i^ reached, 

aiif inyiMin are |ire(!i|iilat4.-<l by alcotiol, and the tireclpitate, an In the 
|ker ^rolvidi. bocooMi. by continuv«l action of the alcohol, altered 


state. And what U true of the collection of parallel Bbres which we call the 
muscle is aW true of each fibre, for the Bwelliug at any part of the muscle a 
only the sum of the swelling of the individual fibres; and if we were able to 
take n single long fibre and stimulate it at one end, we should be able, 
under the microscope, to see u swelling or bulging accompanied by a corre- 
sponding shortening, i'. e., to see a contraction, sweep along the fibre from end 
to end. 

If, in the graphic record of the two levers just mentioned, we count the 
number of vibnilions of the tuning-fork which intervene between the mark 
on the record which indicates the l>eginnin^ of the rise of the near lever 
(that is, the arrival of the contraction waveat tbU lever) and the mark which 
indicates the liej^inning of the rise of the far lever, this will give us the time 
which it has taken (he eontniclion wave to travel from the near to the Air 
lever. Let us sup|>0Ke this to l)e 0.1)05 second. Let us suppose the distance 
between the two levers to be lo nmi. The contraction wave, then, has taken 
0.005 second to travel 15 mm., that is to iray it has travelled at the rate of 3 
metres per second. And indeed we find by this, or by other methods, that in the 
frog's mnscles the contraction wave does travel at a rate which may be put 
down as front 3 to 4 metres a second, though it varies under diflerent condi- 
tions. In the warm-blooded mammal the rate is somewhat greater, and may 
probably Ik put down at 5 metres u second in the excised muscle, rieing po«- 
eibly to 10 metres in n muscle within the Jiving body. 

If, acain, in the graphic record of the two levers we count, iu the case of 
either lever, the number of vibrations of the tuning-fork which interrene 
between the murk where the lever itegiiis to ri:^ and the mark where it has 
finisheil its fall and returned to the Itase-line, wc can measure the time inter- 
vening between the contraction wave reaching the lever and leaving the lever 
on its way onward, that is to say wccan meoiiure thctime which it has taken 
the contraction wave to \ituv over the part of the muscle on which the lever 
is resting. Let its suppoi^e this time to be, say, <>.l second. But a wave which 
is travelling at the rate of 3 metres n second and takes 0.1 second to pass 
over any jmint niui^t be 300 mm. long. And, indeed, we find that iu the 
frog the length id' the coutraction wave may be put down as varj'ing from 
200 to AW mm., and in the miiminal it is not verv different. 

Now, as we have sai(i, the very longesl muscular fibre is stated to be at 
moat oidy about 40 mm. in length ; hence, in an ordinary contraction, during 
the greater jiart of the duration of the contraction the whole length of the 
fibre will be occupied by the contniction wave. Just at the bwinmng of the 
contraction there will be a time when tJic front of the contraction wave has 
reached for instance only half way down the fibre (supposing the stimulus to 
be applied, as iu the case we hiive been discussing, at one end only), and just 
at the end of the contraction there will be a lime, for instance, when the con- 
traction has left the half of the fil)re next to the stimulus, but has not yet 
cleared away from the other half. Hut nearly all the rest of the time every 
part of the tibre will be in some phniie or other of contraction, though the 

(larti^ nearer the slinmlus will be in more ailvauced ])bases than the parts 
iirtbcr from the stimulus. 

This is true when a mu^le of parallel fibres is stimulated artificially at 
one end of the muscles, and when, tbei'efore. each fibre is stimulated at one 
end. It is, of course, all the more true when u muscle of ordinary con- 
struction is stinuilated by means of its nerve. The stimulus of the nervous 
impulse impinges, iu this case, on the muscle fibre at the end-plate which, as 
we have said, is placed toward ijie middle of the fibre, and the contraction 
wave travels from the endplate iu <>p]i<>.-iite directions toward each end, nod 
has accordingly only about half the length of ibe fibre to run in. All the 




tnuK. liierefore, must the wliole fibre b« in a state ot' ooutravlion at lh« MUBi 

It will be observed (liat in wUat has ju«t b««u aaitl i)i« raairacti^ii wave 
hiu liOFn takeu to include not uul^ ilu- cmntriictuin propvr. ilia,' thickening 
Mill K boric niiifc, but aliMi Ihe lelBxiitiou and rvturn (» llii; iiiiliinil form ; ibi- 
lin>L |Mrt >•( ihe \iu\-t: up to the Kuminit of ibi- crast oorratpuids to tbe 
■tinrtcniii^ nml thirk<'niiig, ih*' di-clinc! from the «iimmit onwara crimepontb 
lu tba n-luxBiioti. Biii w« Have aln-wlv iiuiiitcd tliiii tliv relaxation ig ao 
tial [wrt ••(' ihr whole act! imlMil, tn a lortaiii wriiM<, n» fwrntial as t\w 
iMi-iiini: iiM'lt*. 
_ 5 44, Miii'itr linteluri:'. n) miueulnr fibn. S«> far we have 1»ecii dcalin;; 
with the iniK'C'U' a* it whole and m obvcneil with the oaked eye, though ne 
have iueidrjttally s{ii>kvN of fibres. We havn now, ronliuing tiur atlcntion 
cxoliir^ively to skeletal aiusctcs, 1o ocwitider what iDicrwonpic changes take 
[ilatsr durins a eontraction, what are the rehUioHs of the hiatologiciU feature) 
tif (be DtuBcle fibre to tlie act of coulraL'tiuii. 

The luuK cylindrical abealh ofuircoleuiiua is occupied hy muscle subtitaooe. 
After death the muscle substance may separate from the sarcoleinma, leaving 
lh« latter ea a distinct nheath, but durioK life the muscle siilwtanoe is adherent 
to tlie san-okniHia, so that uo Hoe i>f sejiaration between the two can be 
maila out ; liie inovementa of tlif oue follow exaetly all the laovenveuta of tbo 
oii»cr, , 

SaUtend in the mmcle sulioiaiu'e, but, in the mammal, lying for the iikmI 
imK oloao under tiw rtmmleuiina. are a uuiul>er of nuclei, oval in «ha|w, nilh 
their long axo* paralh-l to tbu K-iiiith of th<; lihro. Around each nucli?ti» \* 
a tliin layi'r of grauular-lookitig nubolanci' very Mniilnr In ap|>earancfi to that 
fonunc the body of ii whitr blood'C»r|HiMrb', and like iJiiil ol^en njiokon of 
as aaduTerantiatiid pr»topliu>m. A small •juniility of (ho Mtnv granular itub- 
BtatMv is |in>lo»gi>il (or i«>me dinlanoc, iik a narrow conical streitk from uach 
end of thu nucliip^ along tbo k-iigtli of the fibrv. 

With tha exir|iU<M) of cboM nuclei with their granular looking bed and 
thi? end -plate «r eiid-|ilal<?s, tolie pmentlv dtecribM, all lite xtM of tliv s(Hi«e 
eni'loaod liy the surcolomma from one eoti of tbo Bbri' to the other apjwara to 
tie ouuupit^l by a peculiar material, 'Irintfl niiur/i' riiittiuire. 

It i» ittlli'd rtrialed boauM it is marke<louI. and that along the whole 
IsAgUi uf iti« (ihrv. br tniiuveree bandft [Fig. 'i'i]. stretching right acrwe the 

ir»a K. 



l>i*>ia«NH«nc tanwaanxivm or i llu n aoia. 
iw, iwew-MWM. wa<*U^of « bUBdloctfiuu«cle-(«dsi ft, iWd «utala»M.| 

lihrt. of »ulKlaiicei which is very iruiLipnrent, bri-jhl mAttntiCf, alternating 
with tiniilar Imitds of >til>staii<« which has a dim cloudy appearance, -iim 
mbMunfr ; that ia ta uy the tihrt! is marked out along it^ whole leugtli by 
allamato bright band* aud ''na IxihiU. The bright bands are on an average 
about 1 ^ or U> n aod the dim baniU about 2.5 /< or 3 ^ ibick. Bv care- 
ful focuasing, both brigtit hand* aixl dim tMUfJs may be traced tlirough 
t}i« whole tcickiMMt of the fibre, w that the whole fibre ap])ean to be com- 
piaod uf bright disca lutd dim diacs j>lnocd alleni«t«ly one u|>ou the other 
ili>ng tin* nholc length of tXw f)l>re. th<' arrmngeBMDt being broken hy the 
cnd-jilBM awl here aw) there by the uueWL 


Whcii n mtifctilnr fil>r« is tmi(vd with dilute mioeral itcids it » vtrr ipt 
to hrvnk up tmiisvftrwly iiito diwe [Fi^. S'i], ihr mrcolemmii beio); dinolred, 
or ao nltvnil lut ciuily to dindo into fragmrnta oormpoDding to the diMs; 
•imI ft disc ttMy thus be obuincd so ihiD as to comprise only a Bingle dim or 
bright band, or a dim baod iritfa a thin lnyvr of bright subsiaDce above and 
bolow it, the clearnce having taken place alon^ the middle of the bright 

Wbei) Imted wicii oertain reagents, alcohol, chromic acid, elo., the fihre 
is rerv apt to aplii up (and the splitting up may be aasisted by " teiialiic") 
loiigitudiiially into ouIucuqs of variable thickneas, some of which iioivcver 
may be escee<liii^Iy thin, and are then sumetitnea spoken of m " tibrillir." 
Uolh ihe«i.' di.-H-s luid fitiriltiu arc artilicia) prrtducts, the resultn of a trntiit- 
verse w luDj^'itiidinBl ck-ava^ of the dead, hanlcnr*!. or olhenriiie pn'mr^l 
Uiirt'lir :-ut»lunc<'. Tli<-t may Ri<irv<)V«r W obtained in nlmuU any ihit'KnciM 

thinnciM, and thivt' ai*>» and tibrillie do not by lhriniwlv«« provi' iiiacb 
l>eyond th« fact that the fibre tendit to cleave in tbi- two directJoDS. 

The living fibre himcvcr, Uioiigfa at limei i)uilc glantr looking, thv bright 
bands appearing like transparent giais and iIh; dim band* tikr gnxtnd gtaw. 
!• at other titne» marked with loiigititdina! Iin«s giving rise to a longitudinal 
siriation, sometimes conspicuous and oc<-asioRftlIy obscuring the lmn*v«rai 
StriatioD. In the musclm of some insects each dim band hns a dislinc-l |»li* 
siulc appearance as if made up of a number uf "tibrillie" or" rods" plaoed 
side bv side and imbedded in some material of a diflerenl nature ; moreover 
tbeMubrilln or roda may, with greater dilhculty. W iraoed tbrongh the 
britcht bands, and tJiat at tiroee luoug the whole length of the tihre. And 
there ia a great ileal of evidence, into which we cannot enter here, which 
goes to prove that ill all striated muscle, mammalian muscle incttidird, ilie 
muscli' nuliMtancc is rally eomnoaed of longitudinally tilaoed natural ^'^riVte 
of a c«innin nature, inifieddi-d in nn iitlerfil/riKtir suMiance of a ditTereat 
nature. In maiuiualmn muHcb- and verU'bnile uiusi:le generally theao Bbrillm 
are exceedingly thin and in most case* are not sliarply deBi'ted by nptical 
cbaraclera from their intcrfihritlar bed; in insect muKlm and aoiiie nibfr 
musclm they arc reliitiwiy large, well ilefined. and coiw])ieiiiiu*. The arlirt- 
oial librilla) obtjiincd by tciu^ing may [icrhaiM in some canv* when^ thi.^' an 
exoredingly thin correspond to tbcso natural fibrillie, but in llw roiyontr uT 
cwM they certainly do not. 

In ceiiain insect muscles each bright band has in it two (onoioetimes 
more) dark lines which are granular in appearance and may Iw motrcd by 
iu)e<|uale inxguifying power into rows of ffranuln. 8iuoe Ihev may hv focus- 
sing be traced throusb the whole thickness of the Hbro tde lines arc the 
expression of discs. Freijuently the lines iu the bright bande are so ooiisuio- 
uous as li> contribute a greater share to the iranerene strialion of the libre 
than do thtt dim bands. Similar gniniilnr lines (rows or rather disosof 
granules < mar also be seen, though less distinctly, in vertebrate, including 
mammalian, muscle. 

Besides Ihcac granular lines whose position in ibe bri^dit Ivand is nt-ar to 
tlic dim bands, ollcn aiipenrin^ to form, es it were, the upper ed^re of tbt- dim 
hand Mavi and the lowir eiigi' ••>' the dim band aliovi-, then- mav if al»» 
sometimes traced nmilhiT iraii>ivtir«i^ tbin lin« in tbt? very middle iif lli<' bright 
Iwnd, This liiiv. like the ulhtir lines /or luuidii), is the expn-iuion of ii ilint* 
and has hvea bclil by Mwne obsvrvcm tii rcj>rei*nt a meiuhrane stn-lflied 
arroas the whole thickiieM of the Kbrc and a<lhcrent at the cin'timftu'viice 
with the snrcolemran : in this sente it [» spoken of n« Kt'ixuui* Hinnbroiif. 
The reasons for believing that the lino milly re|»re«ents a <lelin{te mcmbnim* 



ntit liov«v«r appear lo h*! Mk-quaW. Il may Ik >poke» of as tliv " inUr- 
Bi«diat« Vhk" 

Wlicii a thin traiwveno *cctii>n of froEcii niu»clu w I'xnniineil quiu- fradi 
nnilrf a U'tgh |H>wcr, the niii»cli! KiiWtunott within tboMroolcmnin Im M-L*n Co 
lie iiiiirkrtl out intii n niimbiT ot'«nuil] more or lem poljgODal an--iM, nod n 
flioiilnr nrrniii^cnK'nt into antiu RtHy also be seen in transverae »vctii>n* of 
prr]>art.><l niu«cle. though lh« foutiim of the arvw are somcnhat <liK'erenl 
from thiMe Men in t\w fresh living tibre. Tbeec areas are tjiDken of lu 
" Gnhaheim'e areas ;" thciy are very much larger than the dinmcti;r of a 
tihrilla as iuilicateil hv the lon^'ituilinal rtrialioo, and iuile«(i corresuuiK) to 
■ ii'htile bumlle of sucn tihrilln^. TiK-ir existence seeius to indicate itiBt llie 
tilirilhu are nrranKed in hmKitiidinal prisms sep«raled from each otlier by a 
lander nmouoi »f inleTtlbrillar fmbdtauce tiiaii thai uuttiajf to|{ether the iudi- 
vtdual Hbrillie furmiu^ea<th prism. 

I.ji»i)y il may bi- meiitiouni thai not nnl^ are the various k'^i'iIa' liaet 
M tiiii<>« VMibto with ditRculty or quite invistlile, but that eveu tlie di«tii)c- 
Uou t>et«i4^i dim and brij^lit bands is M-caiiioiially very faint i>r obscure, tlie 
wIkiIi' niuwOr stihstaDi*. ajxtrt from the nuclei, a)i[M-arin^ almnnt homogen<Niiis, 

Wiiboot iitutiiiniiiiif to disciHN the manvand varimi* iuterpnetations of the 
al>ov« niul other it<-liiiu concerning the minute structure iif stHat«d muMular 
fibre, «(« may ht're oHiti-nt nunxdvtii with the fDltowing j^ueral coiicluaioDs: 

(1; That thi: miwle ftiilwtaiici: is iiun|>o«H>d of bngituiliiially i)itipos«d 
JihrHlr iprifliahly rylli>.|ricHl in ptncml form and iiM)liably arranged in 

aeiliidimil pri>uiii im)ic^dcd in an iitirrfiiiriUny fiiMannt, which appears 

^M Ian dintrMitialol tlmn the fihrillig thaiast^vfa and which is jirobnMy 
' loous with the unditfcreiitiatci protopleaia round Ihv nuclei. The 
ilertilirillar sub*tnnce stains more readily with gold chloride than il<> the 
fibrillK, and hence in gold chloride tpcdmcua appear as ii sort of Ricshwork, 
vilb InnKittidinal epace^i corresponding to the fibrillin. 

<'i) That the iniertibrillar subsianoe is, relaliTely to the 6brill», more 
abuiMJant in the muj<il«E of some animab than in those of others, being tur 
instance very conspicuous in the muscles of iiuects, in which animaU we 
shiiulil iiniurally expect the less dillerentiated material to be more plentiful 
tlian in the muwlesof the more hixhly developed mammal. 

(.1; That Ihe fibrillH.- and iuterAbrillar subsiance having Oift^rent refrac- 
the fxivrrre. some of the oiitical featura of niunclc muy he due, on (he one 
hand t'l thv relative pr«>)nrtion of fibriltw lo iiiierrilirilliir Mibslance, and on 
th<- uthiT haiiil li> thtt fibrillin not \ieinic cylindricitl tliroiighout the length 
tlip iibri- but cuualrictvl at intervals, uiiil thus becoming lieaded or 
lilif'irm ; fur liMiUice ihfi TDwa of granulni npoki^u of abitve arc by somv 

_ inliil lui comspondine to a^rtgations of inlnrtilirilUr matiirial Htlitig 
ip ihi- *|inrre where the 6l>rilU' arc moat coiMtrictnd. But it dow not seem 
imsiblf Hi ihf) prciteRt time to make any «iatcnK-Qt which will salisJaclorily 
•Xplaiii all the various appciamiior;' mot wich- 

t fiS. Wa mar now r^'turn to the ijuotion. What hapjwns when a contrac- 
tlno wave "wi-cps over ihe fibre? 

MiiwTular fibres may he examined eT«n under high powers of th« micro- 
Kope while they arc yet living and contractile : the contraction ilself may 
l<e *vrt>, hut lh« rate at which the wave travels is too rapid to permit satis- 
bctory observations beiii^ made as to the minute changm which accompany 
crintrDdion. It freipienlly happens however that when living muscle 
Itenn trealMl with t?erlain reagents, as for instance with osmic acid vanor, 
*ub*«^iKtitty prtpiired for examiiuUion, fibres are found in which a 
tog, a thickening: and sbortening, over a greeter or leas part of the length 


of tho librc. hns )>c«n lixcd by the o«niu< ncjil or other ri;agent. Such a 
bul|,nDc obviously i)itl«re f^om n normal contraclion in beiof; coofitie^l to a 
part of the l«apth of the tibiv, whercne, at we have eaid. a Doroial wave of 
contraction, bein^ very much longer than any fibre, occupi« llie whole 
leofflii of the fibre at onoe. We may however repird this bul^ns bs b rery 
■hon. a ven' abbreviate<t wave of contraction, and aaaume tlial the dion^ 
rUible in micb a ithort bulging also take place in a nnrmal oontraclitX). 

Admitting thin ostium ptii^n, we learn fVom such preimnitions Umt in the 
ooDtraeting region of the fibre, while Iioili dim and oright bamU Wome 
brooder acroM the fibre, and corrcNimndingly thiuncr oloiig (Itc l^n^th of (he 
fibre, n remarkable change lakce pinou between thr diiii buiuls, brigln bnnd«, 
and granular Ithi'H. We have wen that in (hf; fibre at rest Ihe intiTinciiiatc 
line in the briglil band is in moat caM« iiiconiipiciioii* ; in the ■■i>n[racling 
fibre, on the contrnry, a dark lino in the middle of thr bright band in the 
porition of the intermediate lino becomes very distinct. \t m pass along 
the fibre from the beginning of the cmilniction nave to the summit of the 
nave, where the thickening ie grcuto^t, this line becomes more and ntore 
tiriking, until at the lieignt of the conlraction it becomes a very marked 
dark Ime or thin dark band, ftiri f/'ittii with this change, the distiuctinn 
between the dim and brijfhl bauds become leaa and leasjnarked; these 
appear to become confused together, until at the height of the contradkni, 
the whole apace between eacli tn'o now conspicuuiiA dark line) is occupied by 
a subiCance which can be called neither dim nor briglil, but which in oon- 
trnsl to the dark line apiMwr^ more or leM bright luid irausparcnt, So that 
in the contracting jutrt there in. ut the heighl of the contraction, a rorereal 
of the atate of thing* proper to the pari at re«t. The place occupied by the 
bright band, in the state "f rwt. im now largely filled by a roiigpicuoua dark 
line which previously was represented by the inconspicuous intermediate 
line, and the place occupied by the conspicuous dim band of the fibre at leat 
DOW sectnB by oompariaon with the dark line the brighter part of the fibre. 
The contracting fibre is, like the fiiire at rest, striated, but iia striatitin i> dif- 
ferent in its nature fmrn the niilunil ^trialion of the resting fibr«; and tl la 
bdd by sofoe that in the earlier phiues of the coutraction, while the old uiilu- 
ral utriatiea is liciiig replaced by ibe new slriatiun, there U a Mage in which 
all Ml rial ion Is lost. 

We may add thnl the outline of the sarcolemma, which in the fibre at rest 
is (piitc even, bcconicj' during the contraction indented oppocito the inlerme- 
diate line, and bulges out in the interval hctweon each two iDtcrme«Iiail« 
linca, Iho bulging and indentation becoming mora marked the greater the 
con traction, 

588. We can learn something further about this remarkable change by 
examining the fibre under polarized light, 

When ordinary light la sent through a Nicol prism (nbieh Is a rhomb of toe- 
land spardiviiied into two in a cortam dircciinii. the halve* being Mbsequetilly 
cemcntrd tngctbrr in a special wav) it uiirl<incucH a change in juMJiig through the 
prism and is mid to be polarited. One rflecl of this iiolarimtiea ia that a ray 
of liglii whii-li lias piMcd through one Xii-ul prism will or will nut pass lhrotu[h a 
•econd Nicol according to the relHtive positcui of tlie two prisms. Thus, If the 
second Nicnl be so plntrd thnt whnl is cnllcrl it* '' nptlc axis be in a line wllh or 
(Mirallcl to the optir axis of the lir«t Nicol the lixlit pns*ing through the first Nicol 
aill also poM through the necoiid. But if the second Nicol be rotntod until its 
optic axis iaat right aagtes with the optic axis of the Anit Nicol uoueuf the lioht 
passing through the former will poM through the latter ; the prisms lu this position 
are said In be '' crossed.'' In iiilermeHiaie positions more or lest light passes 
tlir»u)[h the M-cond Nicol according ti the nngli; betn-ccn the two optic axiv. 

Hence when one Nicol is placed beneath the stage of a mtcnMcope so thai the 



■ Ucbt tan ika mirrvr i* wat Uirough it. anil anoilier NIro) it placed in llie ne- 
' ptfc*. lb* fifid nf rtio aiictoMopc will appear ilHtk •rhrn ibo cyo-ptccr Ntcol b 

n>tAi«d an that luoplir axii in al right aiifira to ihi- ofilic axborUic lower Ninil. 

awl totMMUMiilr ibc light pmmiag ihrouih ih« tower Niool ia aupped br it. If, 

bfvrrrr. l&c optii- nxU of ibe eye- picc« Niool i*]>aralld loiliatuf tlielowt-r NIcol, 

ihr tiybl from the latlrr will pMa ibroneh lb« former aixl the Mt\ will lie bright; 

iMi aa Uw pr«-t>icc« i« emduall^ roiaieif from on* pMilion tn tbe other ibe brinkt- 

nmm of lb* MM will dlminidi «r iiit'r«M4>. 

Baib tbi Nicola are ci>iu|mm*() of doubljr refractive oiaiciial. If now n third 

dacblj r*tr»etiv* mnl«rlnl ba |>laced on the au^, and tlierefurv betwocn iho twn 

INkak. I' |-a«un|c thrrxigh lb«lower Nicol will (inactftain piwilioti of lh« 

dotibh - tuatcrial on the stave, tbat i* to aay. when iu optic dim bare a 

f^ftaJn ^--.I'fn I I'aax thr<>ii|;h il, and alao throogb the trot*td Nicol in tb« eye- 
fiwnt. llrnirt ilii- d'Mildy refractive material on the alage (or nucb paria of 1( aa 
»n Id tbp proprr poaition In rtapeci to their optic aita) will, when the efe-iriae« 
yteal U riMMd, Bp|war illuminated and bright on a dark Sc\<l. In thin way the 
Rafa(as<« of donblj rtfraciiva niatarial Ui n preparation may be ili-tect«d. 
Wbra tDuacle prvpurod «ihI nouottd in OiiiwIk balsam b examined iii 
tb« micnwcope bM«eeo Nicnl prism*, on« ou the tufe b«loM' tb« ohjw!!, Aud 
Ibr iTtbvr In tbo «y«-pJKW, the &bm atand out na bright ohJeciA on the tliu-lc 
(rauntl of thr ti«M wh«D ibe *xe» of ihv jinmiM are crwaed. Ou cl»er 
■tion il ia Mm that iIk- |iAria which iirc britcht nr« chJi-fly th« dim 
Tbia indieaiM Uint il is tW dim bnii<)« which iir«- doiibty rrrrnctivc, 
vtuptnpif, or an cbjcfly tn&de up of itniMHrvpic subaUuKC; thore sceuw, 
•r, to be toam alight nniouni of aniaotropic mibtlsnn In the bt^ht 
. tbnuffh these aa ■ wltole n{>|)«ar fingk refmclive or itotropU. Th* 
Sbn tcnritoglr appcan banded or <tnatc<l with allrmale bunds of anno- 
Iropi^ aod woiropir mnteriiil. Aoconliog to tnoat aulhorB auch an altcma- 
in uf aniaoirMpic lutd ^chi^tlv) i^utnijiic banda which ia obrioua in a dead 
nd pfvnrcd fibre exitta bIh) ia tba living fibre ; but aotue mikinUia thai tlie 
MB|fllire b unifomilr ani»i>tra|>ic. 

SM, when n fibrv iiintracto. la «[Mle of the coiifliAioti previouulT mentioned 
bllMHldun and briicht WniU, ihrrv ia no cunfuniuti bclnceii tin; auiai>tropic 
«d iaotlBpio maMnal. The aniaotnipic, doubly refrnctive baud*, bright 
wia r cnwed Nicola, oocupring tb<' poailion of the dim band* in Ibe reatiog 
Sbf«. rendo doubly refractrvc. bright under enixard NI«olB,eTen at the verjr 
Uflil at Uw coDtraitino. The iiwtm|HC, einely refradirc bnnd.->. dark under 
iMMDd NicfiKoccdpytn); the poeitii>& of the bright liiiml>t in the fibre iit r«M, 
IIMUO Hiiiruiiic and dark uiidcr croeacd Nicoh> nl the vrr}' height uf the 
flsUvctioD. All Uiat can becMO ia that iherRinglTrPl'mcltveiMtrujiic tMuida 
t«naw very thin indeed during the cnnimctiou, while the nnivitnipic ImuiJn, 
rtmigli of courw becomioK thinner and broader ia the contriittion. dn not 
io tbiu M do the iiotropiir band*; in other word^. while both biitidn 
thinner aud bruader. ine doubly refntctive ani!>»trqpic bimd mviii* 

MiaenMe at ibe expense of tito »in(;ly re&activc iiiolnjriic Imnd. 

{ff. We call altrniion (u these Mcta because they "now how complex la 
fe hC "f f-iinimctiDn. The mer<' broadeuinx and «hortt'iiinK of each MClion 
If tba 0bn? i* at ItoUom, a L ran* I- •en (ion of llie ntolecules of tli« iiiusi'lo hiIk 
Canoa. If we imagiin' n cjiniMny of 100 »oldier« ten ranks deep, with l«n 
aM« in rach rank, mpidly, but by u Mriea of );ntdiiiians. to extend out into 
a doable line with 'lO ura in cnc^ line, wc ihall have a roii;;b image of the 
■MVtfmcnt of the molevnlta during a muKCiilar cmtraclion. But, from what 
Ua b«an mM. it ia obvious that tlio moveiiii-nl, in Ktriatei) muwle at l«aM, is 
a Twry eomplicate'l otie ; in other forms of cuntmctile tiwiie it uuiv be, as we 
«kUI aot. more simple. Why the muvr-mcul Is so complicatml in strialeil 
mud*, what purpuaes it serves, why ibu skelcMl intisclcs an; (triat«d, we do 



ii'>( ai i>r»eiit kiuivt. Afitiareutlj' where xtvlfl nod ntjud contraction h 
roguirLHl llit- coiitraclik- t'lMtie iti.ilriauil iiiunck': but how the ttrUtioti Mft, 
an Ui upeak, tli« cuntrii<;ti»ii wo ilo ti»( kimw. Wu latirn't !i»y wlint fbnrc in 
thr net of coDtrnctioii U to be alli)iu.-ij tn iIr* avvfi-ii] jiaiia. Sinci*, durine 
a conlntctioii, the fibrv biilgi-n out more <i])ji'»iti.- In mcli dim dM', nnil 
IN in(Iir:itri) itppotiiu- Id witli brljihl disc, since tliL* •liin ili>c i> luorr largely 
('(irii|)D«cd i>f HMiKolriijiIc iiint<-riitl lliiiu l.hc Jval ul' thr fil>n-, nnd »iticc the 
aiiiHDtropic nintcrhil in ihi! |»<H>itI'>ii of llie dim disc incrvtiMv ilnring a con- 
l nidi on. we might iwrlmjw iiifvr ihiil thr dim diec nilht'r ihnii the brizhl 
diai: It tho csk'iitially active niirt. Ae^iiniiiij^ that itic Dhrillar Euhstance is 
more ahundaiit in the dim discn, while rliu interlibrillnr substance U more 
abutidajil in the bright disc*, and ihiit the fibrillar subUaoce is anisotropic 
(and hence the dim discs largely an is n tropic), while the intviKbrillar sub- 
stance is ieotropic, we niigbl also be inclinet] to infer it is the fibrillar and 
not the intertibrillar substance which really carries out the contraction ; but 
even this much is not yet definitely proved. 

One lIiiD]{ must be remembered. The muscle sulalance, thouj;!) it po*- 
»et«cs llie ooniplioated structure, and ^oes tbiriugh the remarkable chan|^ 
which we have deacribed, is while it is living and iuutct iu a condition whicli 
we are driven to »])Mik of ai *cmi-IUiid. The whole ut ii is e^ttciiiinlly nn/itile, 
Th« very act ot'coiilrartioti indeed ahows thk ; btit it it> uiohile in the Mnse that 
ii'i part uf it, vxivpl of <!ciui'<R the iiuciri and sarcnlemma, nvither dint nor 
lirifcht giulKtlnnct-', iii-ilher lihrJUar nor intvrfilirillar aulMancc, cnii be regarded 
an a hard and limt structure. A minute nematiiid worm hat been xeon wan- 
dering in the midst of lliesulislnnce uf a living rnntritctilc fibre ; as it moved 
nlonf:, the. muH-lcsnhstHnce gave way In-fore it, nndclowd up again behind ii, 
dim bandx and bright bands all falling back into their proper placo;. We may 
wippotv that in this case the worm threaded its way in a Huid interfibrillar 
Buhslance between and among highly extensible and elastic tibrilltt'. Bui 
even on such a view, and Mill more cm the view that the fibrillar sulmtuneu 
also was bruken and closed up again, the mainieuRnce of sucbdelinit* bintct- 
loKical features as tho«e whidi we have dwcribed iu material so mobile can 
only be etfecied, even in the fibre at rexl. at mime considerable ox{i«uidituro 
ofeiii-rgy : which energy it may be ex|)ecieil haa a cJicniical sourctv During 
the CuDtraction then' i.-> a still further exjieudilure of energy, some of which, 
■■ we have seen, nmy leave the muscle u-i " work dune;" thi* vaergy, Uke- 
wiiH', may be rxpccti-il t<i have a dicmical source. \Vc miirt, thfirelore. now 
lura Iu the chemistry of muscle. 

The Cliemistiy of ^ftt»r!f. 

$58. We said in the Introduction that it was difficult to make out with 
certainty the exact chemical dift'eremes between tlead and livios «ui>- 
Mance. Muscle, however, in dyini^ uudergues a reuiarkalile chemical eliaug*, 
which may l>e studied with comparative ease. We have already said that 
nil nm.tcles, within a certain time after removal from the biuly, or, if still 
rcRuiiiiin)c part of the budy, within a cerLaiu time atliM* " p;neral " death of 
thv body, low their irritability, luid that the low nf irri lability, which, even 
when rapid, is graduul, is unccwded by an event which i* somewhat more 
sudden, vit.. the aiirmiicu inio the condition known ns ri</or utorlit. The 
occumonce of rigor mortis, or cadaveric rigidity, ns it is sometimes called, 
which may be considerwl ns the token uf the death of the muscle, is marked 
by the following features : The living muscle poeseBKe n certain tranj-lucencv, 
the rigid muscle is distinctly more opaijue. The living muscle is very exteu- 
»iii|« and elastic, it stretches readily ami to a considerable extent whtin a 


nvte^i b bUDi; upon it, or vlieu uiy truction is applied Co i(. bui a)ice>lily 
innd, under normal circa nuuuwce. c«iupl«telv relurna lo iu oriKiual leiif|;tn 
twWn tbe w«i|;ht or moUan is mn->ved ; as w« shall see. however, the 
twpfdiir and cuiupleteuen of the mtuni dejie>iiU on tlie c»udilioTi oPthu 
nDKlr. a xell-auuriahed activo inuacle n->:aiiiiiiK il» normal lcu;,'Lh much 
Mnr* mpdiy and cuoiplelcly thnu n timl uiid cxhausiud muacle. A diwii 
ri^d MiMaJe ia muelt l«a» #x[iiisil>li>, and nt ihv Mimv lime miidi lean dantic : 
lh» MHela DOW nquina oonri<Uniblv I'on-v to xiretcli it. niid vrhi>n the forci' 
h iVMand, Aot» not. aa before, ruturn to it* fomivt loiijclh. To the Imtch 
tbt nglMl maicle hiw loK miirli <>( il* formtr sofliwff. and bun become lirmvr 
■ad Bar» raaiitaot. Tbe cntmnoc iiilo rigur morti* u, moreover, itccurapn- 
itini bf s ilioneniiig or contraclion, irhich may, under nrtain circunMaiict*. 
W (■■Mdrnhle. The energy of thi« coiitnietioo is not great, ao iliat any 
MUial •borteningMenailr [irevcttted by the prcscnceofeveu a Blight oppoaing 

Now tbe cbenii<^l features of the dead rigid mu»cle are also 6trikiu|;ly dif- 
I trrtnl Tnttn those of ibe living muscle. 

t W. If a (if-iJ tntiM/e, from which all bl, teiidon, fascia, and connective 
bate Ijeaiaa much a* puaaible mmoTcd, andHbicb baa been &eed from 
,„. _ !>r the injection of " nonunl" ulineaolution, be minced and re|Matedlr 
•■•bed with water, the wii!ibiii>;ii will <-<>maiii ciTlitlu f irma of albumin nnil 
•vitain eitntcUve iKxtiex, of »)iich we •hull ^\K-ii\t iliroi-lly. Wbt^ii tbe nii^h- 
ir^ bia bevB oontinuud until ihr Kii.->h'W'iiti.'r give* no proteid rmetioii. a 
hm portion of tnuKb' will iilill ri'muiii iitnliiwilvvi). If lhi« l>c treated with 

■ tOpiraetlt. aolutinn of n iiuutnil itnit, ummmiinm chloride Iwin^ (be be«t, 

■ luM portion of it will Uvmu- dlwilvcd ; the Foliitioii, htiut'vcr, w more or 
!(■ UBparfiKt and Hlten vith didicully. If tbe filtrate be atloncd to full 
it9p vf drop into a large i^uantiiy of distilled water, a while Hocculent 
MU«r will M j)reeipitat«d. Tliis tlocculeut pret^ipitale ia iiiytMin. Myosin 
»t(ir»ieH. ifiviniE ibe ordinary pmteid reaction*, and having the tame geu- 
titi rlvnieoiary eom|N3ailiu« a* other pr»teiilit. It is soluble iu dilute sidiue 
Mhliuiw, rejieciallr tboae of ammonium chloride, and may be classed in the 
^oknlia family, t]»ough it it not xo eolubh' an pa rag In but in, requiring a 
Nrafn-aolnUan of a neutral mlt t<t dinolve it; thim, while soluble i»a5 
•rlOptr cMt. solution nf giich a #nlt. it w far len ihiIuIiIc in a 1 per cent, 
•cimfaa. wtiieb, B« nr have SM11. rvudilv diiwilvt^ piimglnbulin. Fnim ila 
•(■ina la iMulral saline Mlutioii it i* prccipilntol by Mturntion with n 
■Mtal alt, preferably sixliuin ehloride. and may be piirilieil by Iwing 
•kM with a Mturale<i »>luiio(i, diaaolved sgnin in a weaker solution, and 
rr I by Mliiraiioo. Diavilved in saline solutions it readily conx- 
HI' I healed — i. «.. ia conveHed into coagulated proleid — and il in 
•wiliy nf notice thai it congululcd at a coinpttratively low toinpernlure, viz., 
*b«l 08' C ; this il will be remeiulvered lb the temperature al which tibriii- 
in It oiagulated, whereas paragloliuliu. scnim-alliumiu, and many other 
pteifis do wA coagulate until a hichiT lem|ienilure, 75° C, is rea^'hed. 
Skttirf)* of myoeiu are precipiiatt<<l by alcnho), and tlie precipiiate, as in tbe 
mt <■•{ otiirr pn>leid*, IwennieK, by continued action of tbe alcohol, alterol 
aa*<\«gulBie<l imraluble prnt'-id. 

VTe bavc seen that par^lobulin. aitd. indeed, any member of the globulin 
(nap. b vciT midily changed by the action of ilihite acida into u body 
aSta 'M^-<iANiniN, chamot^riited by not being soluble viilicr in water or in 
Ah* Mlioe aolutions bul rciidily tolublc in oiluto acid* an<t nlknli<«. from 
ili Mladom in either of which il i« precipitatdl by iieutralintion, and by 
I iW &cl that the sotuliona in dilute aciils and alkalies are not ooogulated by 
tML When, therefore, a globulin is diceolved in dilute acid, what lakes 


piloe ianota Di«re solutioa but a ch^tiiical change; the glMmliM caniint be 
got batik ft«tn ihe eohiliou, it h»s been chnn^red iiilo «ci>l-nlhiimin. 8itn!- 
larly vhen (>lubulin is diseolvwl ia dilute alkaliefl it i? changed into n/^1/4- 
nlbumin : and bruadir B{>eakinK alkali-albitmin pr«(npiui«d by Deutraliu- 
tion i-uu Ite cbsujted by Boliition with diliiie ncidM into add-albutuin, uid 
add-albiiniiii by dilotc mikalies itito alkali albumin. 

Now my<H>iR i° nimilurly. nixl even mure readily tlian is t;I<>l>"li<i< M"' 
vertei] imn iioidnlbumiii. niid by Ireutiii); a niU!«lc, either M-BBhe<l or OM, 
directly with dilute hy()rrirhli>ri<- ndd, the myiK>in may be c»uveri«d iaUt 
lt«i(l-nll)uniin and duwilvcd out. Acid-nlbuinin oblniucd by dit<Milvitig 
riukIo in dilute acid ux'd to be culled minlo'iin, niid it uxed to Iw Mid that 
n n)u»cl(! ointained «ynloiiin ; th« ntURclc. howcrcr, contain* myovin, nut 
i>yn[iiiiin. btii it may bo ueeful to retain the word syntotiin to drtiotc nrid- 
klbumin ohijiined )>y iho action of dilute ncid on niyotin. Jty ibe notiun of 
diluU' nikniira, myosin may «imilarly bo conv«ricd into alkali-albumin. 

From whul bti« be«n above Hated it is obvious that mvoein has mnny 
annlofpes with fibrin, and wg have yet to mention eome Btnkin); annlocin; 
it h, hoirefer, much more soluble than librin. and speakinf; generally it 
may be said to be iuterniediate in its charaeler between librin and clobulin. 
On keepiuft, and especially on drving. its solubiUty ia much diminislied. 

or (he suliaiances which are feft in washed muscle, from whidi alt ibe 
mvosin liaa been extracted by ammoniuiu chloride solution, little b known. 
if iraabed mii^le l>e treated directly with dilute hydroobloric a<rid, a targv 
p«n of the material of tlie mumle pattM, as we Imve it»i<l, at once into svo- 
touiii. The iiuantity of •ynctmiii thuft ob(«in«<l may he taken aa roughly 
rqnwBeniing tne ((uantity of rayoi>in provioutly esi>iting in the mutclc. A 
more prolonged action of the ncid may distolrc out otlior protcidf, l>««i(lei 
inyiMin, left afler the washing. The portion inxolubk- in dilute hydro- 
chloric ncid oUNsts in part of the ^tatin yielding and otiier siibelasces of 
the wrcolemma and of the conneolive and other timuos between tb« bun- 
dles, of the nuclei of thcee li^eiiee and of the librw themselves, and in part, 
possibly, of some |)ortioDs of the muscle subetsncc itself. We are not, now* 
ever, at preaeDt in a position to make any very deHniie sutciuent as 10 the 
relation of the myosin to the Mtructural lealurai of muade. Since the dim 
bands are remtereii very indiiiin't bv the action of a I" per cent, sodium 
chloride ^lutinn, we may, |«rli(ni^, int'ir that mvwin enters larKely into the 
oompooition nf the dim buul^ mm I Ik relbre, of the librillni; but it would 
be haznrdimx to nay much itu'ii; iluxi Uu.h. 

^60. Living nuwie may be fmiccu, and yet, afYor osrtnin precauiiom 
will, uo being ihawml, n:)^in its irritability, or at all evcnl4 will for a time 
be fiHind to be still livinc in thu wiwc that it ha* not yot paavcd biio rigor 
iaorti». We mayi therefore, toko living musole which has bemi froMU as 
still living. 

If liriaif fttalrnetih mtuelt, freed ns much as poMiblc from blood, be 
frozen, and while frozen, minc^rd, and rubbed up in a mortar with four timss 
its weight of snow cunisining I per cent, of sodium chloride, a mixlur« b 
obtained which at a (em)iernturo just below Q" C «■ sulKcienlly fluid to ba 
filter«<l, thouuh with ditfieulty. '1 he slightly opntevcenl filtrate, or wii-"'^ 
plamia iw it in calleii, i& at tirsl r|Uile fliiid, but will, when exposed 
ordiniiry lem|HTaliii*, become a solid icily, and afterward separate into a 
e/ol and Tiiiri. It will, in fact, coaeufate like blood-plasma, with ibis dif- 
femiK'C, that the clot itf not llrni and Rbrillar, but Ioom, granular and lloc- 
culent. During the coagulation the fluid, which before was neutral or 
slightly alkaline, l)ccome« distinctly acid. 

cnAxose tn a mitscle Di'itixo contraction. 

Tlkf dot b mytmn. It givn ill tbe raifltioiu of myotiit obtninvil (Vi)iu 
<1mcI wnacl*. 

Tb» «ran rontaitu tn altKimin -vtry timiUr to, if not Hiciitimi wilb, 
vrtim-mlbumin. ■ globulin <)ifl«rin^ ■umi^whiU I'rDni, Kn<l cmi&ulitiiig at it 
)<>««r iMnpvnilun' ihuD pn»f;lobiilJii. mn<\ which lo (Itningtiifh it IVoiii tbe 
globalin uf bimxl hiu bwD (.-itlleH mwylohuUn, eorav ii|h«r jiroti-itli' ohicb 
Dol bv (UscHbed heiv. and various "estnclJTea" of vrhifh nrp fbaM 
. dlrectlr. Such muscles as are red also conlnin a buiaII quantity of 
[lobtn, and of anotltet allied jitgnient allied hitlolurmatiH, to which 
ptCMaia. iotlnxl. Ib«ir r«dna« is due. 

Tkoa, whil« demd muwli' cunlaiw myoain. stbuniiD, aud Mber protcids, 
•ztraetir**, ami ccruin inuluble nuitten. in^ther irilh gi'laiinuus aud oth«r 
wib*anm Dot referable tu tb^ niUNcJe Kulmtam-c iliwlf, living mii.*cle euniaiDe 
OM aa^Min, but aonc iulwtance or •nlwtancr-!' which Ixuir MMDewhnt Ihf Mime 
n-Utiun Kt mTottn thai the ant««cdfDi» of tikrin d» to fibrin, and which jitve 
nM> lit BijiMin u]>nn iW denth of the muscle. There arc, imltiHl, rutuMUis for 
thinktDff that thv inynHn ari«c« from tlu' (»nvcnii>n of n prcvioiuly existing 
bndy wfiidi may be cntlnl myMino^fH, and that tli« c»nvcn>ion lake* [ilaee, 
nr nay lake placf. br ilic iiction of n special fermont, ihv L-oovcrsiaii of 
Byaaaunn into inyodin bein^ viry analogous to the conversion of tihrinogon 

W« nay, in fact, apeak of riitor mi>rtU na characieriEed by a con^'nlation 
of Um muacle-plasfna, oomparanle to tbe coaijulation of blxod-platmn. hut 
JUfciny fWmi it inaanucli aa tbe product ia ixrt tibrin but myosin. Tlie 
rijtidliy, ibe Um of vupplenea*, iimJ tbe diininl»lied translucency appear tu 
Iw at kII e\-«iita hir;(^lv, ihotijtb pn>hubty not wholly, due iti tbe ehunife frutn 
tbe lltiid plMHUt lo tlw tolid niyu«io. We miebl oonijmre a living imml« 
t" a nnmber nf fine tramparmt ai«nihr«»ous tnues containing plood-pln«niB. 
Wb«9 ihla blood- plasma entered into the "jelly" stage of con^ulaiion, tli« 
mlvin of tubffi would present many of the phennmenn of ngor ntortb. 
Tbry nouM lose much of their suppleneaa and tronshicrncy, and aoquiiv a 
evrteiB aoKMinl nf rigidity. 

(61. Time b. however, one very marked and important diBereoce be- 
imva Um riffor mortis of muici*- and tbe angulation of blood. Blood dur- 
bi^ iU onaipualion undergot* n uligbi chan^i' «4ily in its reaction : hut mus- 
eW 4ariag the oniet of rieor mortis liec«'nn- diDlinctly acid. 

A livm muscle at n*t in in rcAotiim miilnil, or, pumibly from aome 
"TTwfrr uf lymph ailhering to it. fninliy nlkiiline. [f, on the other hand, 
tW naelian of a ihorunchly rigid miiKch' he ttvleil, it wilt Iw found to Im 
MCM (bitlnctlr add. This development of an acid reaction is witueaied not 
obI/ in tbe solid iiiitotiched fibre but alw in expresacd mttMl»-planDft ; It 
•MBa tn be awH>etnt«) in mmv way with ibc nppearnnce of the mynstn. 

TW exst-l caumtioti of this acid rcartion hns not iil urrscnt brcn clc«riy 
Mnrknl utit. 8iuce the coloration of the litmus priwfuccd is permanent, 
nrhonir acid, which, as we shall immediately state, is set free at tbe i<ume 
tine, rann"! he regarded ah the active acid, for the reddening «if litmus 
neoduoril by cnrlxxiic otid »i)e«iily dbappean on exposure. On tbe other 
Inod il ■* [v>wi)>[i> ut rxirad fnxii n^'id raiuKle a certain ououtity of lactic 
•did, or nuber of a varii-tv of lactic uctd known an urcyilactic acid : ' and 
il Im* baea thought that tdc appearanoe of tbe iict<l reaction nf rigid muscle 
m da* lo ft new jbmation or to an increased formulii>ii of thin Mrcolacllc 


■MD «wMla> or lactic uM. «Mc4i ua iMaatfto. tiarlaf thir midi ooiDpotflM), 
~ ta(lMltt«HibM>»4 afsddlTlaiheuMSUiyolllKlr ilMi^ta. TbomiHty 
tt dWlatiil«b«d » aFMlwUcicU. 



a€td. Then is much U> he eaid io favar of tbia vieir, but i( cannot at 
pnaent b« regarded a* eeiabti^hed beyoad dispute. 

Coincident vvUh the appearance of tliia aoid reaclioo, tbou^b. ae we have 
said, not the din>ci cause of it. a lari:e development of carbonic add laka 
place wbeu luuscle becomes rifcid. Irrilable living muscular sulutauce. like 
all liviii{{ aubittaiice, in coutiuually reapiriiig, that h in i>»y, U cuutirmatly 
consuming oxyjcun and ttiviug out carbuiiic aciil. In the h^dy, the arterial 
bkiod ffoEug In the miia<^^ givt» up some of its oxygun, and gain* ft quiintiir 
of cartioiiit' acid, tliiiii bccuniiug venous iis tC puKM* through ll>e iniiwlc 
Cii]>illarit«. Eviru nlU-r rviiioval IViim the bcMly, the living niujclc coiilinuea 
to taku up front the vurruunding atimifphorv a certain i]uantity of Qxygta 
and to give out n certain quantity ut' carbonic acid. 

At the onset of rigor niorlis there is n very lari^c and nudden inctvaae in 
this production of cnrbnnic acid, in tact an oiitliurct n» it were of thnt gst. 
Thi« ia ft )ihcn(imeiion dcecrving suecinl atlcntioii. Knowing that the car- 
bonic ncid ivhicb is the outcjiue ol the respiration of the wbole body i# the 
nwult of the nxidatioD of carbon-huldiu^' aubslances. we might very natu- 
rally suppose that the increascti production of carbonic acid atteodaul on the 
development of ri;>or niorlia i» doe to the fact that during tliai ereut a 
certain quantity of the carbon -holding cunatituenl« of the niucole are sud- 
deulv oxidized, llut Huch a view is negatived by the following facl^ : In 
the itrst place, the increased production of carbonic acid during rigor inortu 
is not accompanied by a correagxindiug iucreaAe in the oouauiaption of 
oxyeen. In the aeooiid place, a iiiuacle (of a frog for inhtance) oontaina in 
itMlf DO free or loivcly attacbe<l oxygen ; wheii subjected Ut the action of a 
merctirial air-pump it gives olf no oxygen to a vacuum. oHering in thi* n- 
•peel a marked contrast to bhiud ; ami yet, when placed in an atiuodphero 
free from oxygen, it will not only contimifi tu give off carboDic acid while U 
rtDiaini alive, but will also exhibit at the onwt of rigor mniti* the sntne 
incnawd production of carbonic acid that i* ehonn by n muwlc placed in 
u umoaphere containiitg oxygen. It is obvioui that iu »uch a caM- tlw 
oarbonic acid does not arise from the direct oxidation of the muscle sub- 
Glance, for there is no oxygen present nt the lime to carry on that oxidation. 
We are driven to suppose that during rigor mortis, some complex body, con- 
taining in itself ready formed oarbonic acid, so to speak, ifl split up, nud 
ihiii carbonic acid is «t free, the process of oxidation by which tliat c«r- 
I>onic acid was formed out of the cnrbou-holdiug ooustitueuta of llie musol« 
haviuK taken place at some anterior date. 

Living reitin;: mo^de, then, in alkaline or neutral iu reaction, and the 
subdtance uf iia tibrtu contains a coagulable plasma. Dead rigid muscle on 
ibe other hand in acid in reaction, and no longer oouiains a ctiagulablc 
jiliunui, but in laden with the Kolid mrosin. Furilier, the change from llie 
jiving irritaldf condition ^> that of rigijr mortis ii> accomjninicd by a largv 
and Kudden dcrelopnicnt of cjirbonic aoid. 

It is found, mortvover, that there is a certain amount of {wrmlleliMa 
between the intcnsitv of the rigor mortis, the degree of ncid rcucUon and 
the (quantity »f cnr^lic acid given out. If wc suppo«e, h wo fairly 
mny do, that the iutensitr of the rigidity is dcpeiidunt on the minntity of 
myosin defweileil in the fibres and the acid reaction to the development if 
not of lactic acid, at least of some other subslanoe. the parallelism betircvn 
the three products, myooin, acid-producing substance, and carbonic acid, 
would suggest the idea that all three are the I'c^'ulls of the spliiting-upof the 
•ante highly complex sulwumce, Xo one has at present, however, succeeded 
in isolating or in otherwi*e ilelliiiti-ly proving the existence of such a twdv, 
and though the iilen teems tempting, it mny in the end prove lotally 




I n. A« to ttie nlh«r prnteids of tnuscle, such ts the albuiDin and the 
yMmHa, we know as yet »i>i)iin);' rotmrning tl>e parts trhich ihey pUv and 
Um elMBfe* wbicli they undergo in itie livii))> muscle or in ri;;<>r morti*. 

Biriiu the Jot which ta found, and that nat iiofre'iiienilr in nbundnnce, 
in ibe cunnectira tiaane between the fibres, there is also ptva^ut iu the tnu«- 
cwkir aalMtance wiibin ihe MircoIeRtniA, Kluays n-jme, and at timea a Krout 
AmX. of fat, chieflv ordioary fai. vii.. Mearin, [Mlmitin, and olein iu variable 
pfopcwtioo, but also ihe lUAfe complex fat K-Htbtn. Aa Iu the AiDdivn uf 
tba* arvwrKl &ta in tite life of the minwle ne Icm-w little or nothing. 

OKtiwk f iimtm, ibe third of the (hre« grnit claiuu-ii in which wc may ^ruup 
Um CBVfgy-boldhlK aufaMJUtcea of which thi? animal body and it.-< t<icid an- 
alike cunpcMil. tic, proteidit, &(, ami mrbobydrat^-M, are rvprvMMite<I in 
iBUfcle bjr a nvculinr body, ^yerHjm, which n'l- »hiill bnvi' to xtnily in detail 
btarno. ^\«mu•t here nK-rely wiy Ihnt glyoogrn i» a Ijorly cIiKwIy iillicfi 
bt March, haviae a formntn, which may Ix- included under the gt'iH-ral 
(maola fi>r ■taroMS.Jr (C,H,,0,), and may like it be c»nverled by the af-lion 
i>f acwl*. ur by the action of paniculnr fermente known as amvlolTtic fiT- 
Mtnta. into Mtme form of Migar, dextruee (CiH|,0,). or some allied sugar. 
Maoy. if not nil. living niMM'lee contain a ivrtain amount, and some, under 
rartaia eircuniiitances, a cun^idcrable amount of glycoceu. During or after 
tianr lawiiu this gtycoji;eo is very apt to be converted into dcitroee, or an 
uBed angar. The mnsclea of Ibe embryo at an early trtage contain a relu- 
ilnslj eoonnoas quantity of KlvcuKeu, a fact which attgi^iB thai the xlycn- 
fun M moacle n carbohydrate jood nf the u)ii$cle about to be irruuglit up 
nto the living muBcular »ulMta»ee. 

TW bodica which we have calle<l ejrtmefiftt are numerous and varied. 
TImt art wpeciaily intcrettiiig. since It lecnis probable that they uru waite 
y€vaaeU of the mclabniigm <>r ihc niui>ctilar subsianoe, and the study of 
then BMT be expected to throw light on the chemical change which luus- 
cabr MiHtance nndcrgno during life. -Since, as we shall see. musctilar 
wbaianea forms bv far the grniter part of tlie nitrogenous, that is. proteid 
poetioa of the body, ihe nitrogenous exlraclix'cs of muscle demand peculiar 
attratioci. Now the body urtti. which we i^hall have to study in detail later 
«a. &r nceetis in importance all the oiher nitrot^nous extractives of the 
body aa a whole, since it is practically the one form in which nitrof^noiis 
WHCaa loves the body; if we include with urea the cineely allied uric add 
(whieli for present pur]Kisee may aiuiply lie regarded! as a varietr nf 
Br*w>. we mny «ay that all the nitrofren taken in as food sooner or later 
kav(* tlw body aa urea; cumpari-d with ihii> all other uiiniKcnoua waste 
ifarown out from (be bwly is Inugnittcant. Of the urea which thus leaves 
iIm bodv, a iv)fiuderal>le portion must at sonic time or other have existeil, or 
M afaak more eiactly. ilK nilrogi'ii niLj»t hiivi; i-xlHtcd nx the nitrogen of the 
pnMMa of nnsailar ntulMtan (.■.■. Ni-vrrthi-liiu. no un-n nt all I-", in unrmal 
modltkaa. pieaent in muncular subvlatm' citht-r livinj,' and irritabli' or dead 
aed rigid: un-a iiin-» not arise in muK-uIar Milxitanix- il»ell' ns oik- of thir 
tMS0adiat« waste pniduct* nf miiu-ular Mibstance. 

Tbfvc ia. however, alwuyi^ prrat-nt in relatively considerable amount, on an 
avvfkp ab(«ut U.'i.S |)er ocni. of wet muKclc. a remarkable body, trrttlin. Tim 
■^ in one sense, a comtmund of urea : it may be split up into una aiul sar- 
aain, Tbia latter iKMiy is a methyl glycin, (hat w to say, a glycin in which 
lilbyl has li^n substituted for hydrof^en. and glycin iiwlf is nmido-ncetic 
acid, a ctiit)j>ouud nf amidof;en, that is a repre«entntive of ammonia anil 
MStie acid. Kence kreatin oinlaint urea, which has close relations with 
uaasunia, toi:ethcr with another r>>prefentative of amniDnia. and a surplus 
«f carbna and hydrogen ermnj[ed as a body beloDgitig to the ftilty acid 



•eriM. Wc sIiilU I>nvc to reUiru Lo th!« kn>iiiiii niid «ondd«r its nktioo ' 
urra und Ui muiidi.- nhcn wc oome lo deal with urine 

The oilier iiiir<?gciiou» oxirnctivcH, •ii>:)i hn kcniiD, lij'puxanthiti i.or 
earkin), xaiilhiti, luuriii, vtc, ix-cur ill snitill ijutiiitity. nnd a<xii not be dvelt 
00 here. 

Anibug Doii-tiitrog«iiouB extractives the most important is th« sarcolacUc 
ttcid, of which we hiivo nircndv i^pokcii : to this may be added sui^ar in sonie 
fom OT other either cumiDt; Iruni glvcogeo or from fome other eoun.'e. 

The nsh of muscle, like the a^ii ol' the blood corpuscles, and, indeed, ihe 
usli of the tiMueti in frenersi, ea dUtini^'uighed from the blood, or idasma, or 
lyin)>b on nhich the tit«ue« live, i« charBct«riz«d by the nrepon<IeraD(« of 
|Mlai«iuni aalt> mid uf phufiphates ; these form, io favt, nearly dO per ceut. of 
ihe whoh) a«h. 

j 63, Wc may uuw past on to the queetiou, What art the chemicsJ 
cltnnges which take pbive when a liviii^ nstinK mutcle entvn into u conirac- 
linn? Tbcw! clioii^ arv mou evident otW Uie inuwle hait been aiibjcc 
lo a proloDgcid lotuiiu.i ; hut there CUD be no doubt that the chemical mt 
of It li'Miiiiii' lire, likd the pliysimi eruiU. dimply ilie itum of the multa 31 
tliv iiinstitiivnt »ingk- contraolioiiK. 

In iho tint tilnci.- llii? niii«cl<- bcconicai add, nol so ncid ait in rigor luortia, 
but Etill Huttiuiciilly so Hl\cr n vigorous tetanus to tiini blue Ittmtis distinctly 
I'ed. The cause uf the acid roncUnn, like tbnt of rigor mortis, is doubtfiil, 
but is in all prubability the same in both niiK-s. 

Ill the secoDr] place, a coDsidvmblc (lusnlity of cnrbonic acid if set free; 
and the prodtiftioii of carbonic ncid in muscular ooiitrsction is ullogetker 
»iiuilar to the produeti'iD of carbonic acid during rigor niorti§ ; it is not 
accompanied by any corresponding increiise in the consumption uf oxygen, 
lliis n evident even in a muscle through nhicb the circulation of blood k 
villi going on ; for though t)ie blond pawing through a coutractliii; muscle 
gives up more oxygen ihaii the bliHHl piu^iug through a iwting idukcIo, the 
incmsi- in the aioounl uf uxyj;en lukitu up futlii bu-luw tlie incruuc iu the 
carbonic acid given out. But it is ntill more mnrkislly nbowu in a muscle 
removed from the boiiy ; for in «uch u muscle both tUv coiitiuctioii and the 
incr^-iisr in tbc |)roduclion of (rarbonii- sciil will go on in the absence of oxy- 
gen. A frog's muscle auapeodetl in an ntnioxtdurc of uilmgcn will remain 
irilable for some condderable time, and ut cttcfi viguroua letauus an incrcaee 
in the pruductiou of carbonic ncid may bo readily nsccnaincd. 

.Moreover, itiere seems to bo a con«spood«ncc between the eoeivy of the 
cootraotiou and the amount of carbonic acid and the degree of aoia rewition 
produced, so that, though we are now trending on somewhat uncertain ground. 
we are naturally led Ui the view that the emcntial chemical proc«« Ijing at 
tJkc bottom of a mu»cular oontraciion as of rigor mortis is Ihe spliliiug up of 
some highly eomplex subtlaaoe. But here the reBemUaooe between rigor 
morlio nnd cootraclion ends. We have no satisfactory evidence of the formii' 
lion during a euutraction of any lio<Jy like myonin. And thb dilference in 
cJiemical nwilu tatlii-n with an iniiuirtant dilfereuce between rigid muscle 
nnd contracting niunclc The rigid mUHelc, ui> we have seen, heeocuca leas 
extensible. IcMs ehistic, IcsN (nin»hiii^it; liic i-outraoting muscle remains no 
less transhicenl. elastic, and extensible ihiui the renliug muecle, indev<l, there 
arc rmsons for thinking that the muscle in couLraeting becomes actually 
more extensible for the lime being, 

But if during a eontmction myosin is not formed, what ehaiigm of protcid 
or nitrogenous matter do take place !^ We do not know. Wc have no evi- 
dence that kreaiin, or any other nitrogenous extractive. Is incmaaed by 
coniriictioD of muM-le ; we have no evi<ience of any nitrogen waste at all 


alt of n coHtmcUun ; nnd, indiml, ii» w thmlt MC Ulvr oil, thv tlxidy 
ih» wsiUr prodiiCU of lti« body iw it whulw Icjid u« lu believe that th« 
wtgy of ifav vnirlc don* by lb« qium-K-* of tho IkkIj: oo«im from the polpii- 
tU —Br g v (if ckHmo ronitwundi. mid noi of nilngcQ ootupounds »1 all. 
Bat la ihi» point wv aha)! hnvv (o return. 
^ t M. \V» nay ram up the elt«tnistrr of muscle somewhat la follows ; 

Duriae lift tbe tnoKtilur eubetuDcc is contiDually taking u|> from the 

|blo«Ml, tnat ta, from the lymph, protcid. fatly and catb'ihydraie lunterinl, 

[■■IbM iMrttMv and oxyneo; theiw it huihU up into itself, bow we do itol 

kutxB. aod Ml forms ih« peculiar moipiei liviBg muscular aubstaui-«. Tlic 

[•srnct oalure of tiita liviu|{ Kibataoce ii unknown to us. What «f do kium 

1 1» tbkl it ■• largely coiojw«ed of nrateid tuaterial, iiud Ihai kucIi budir* nx 

■jwiBogni, inyogloUiliD. aud nlbumin have voitieihiug to do with tiitt 

J of it up. 

DBrtei nU tlito muscular »ubiilan<<e, while litkiiijc in nwl building ilMilf 

ttwtNiI of ur by moiiwof tl»eabov<:-iuentioiii;il malvtiiik is cHuittiniaily giving 

wC oubaair acid ami cootiounlly funniug nilmgvnouN wnrtv tuch as kmtin. 

It kW prubably );iTiH oB* aofoc amount of wireolactic a«-id, and poMibly 

aiimr DOD-nitngMious walite m«tlvn>. 

I>unng n oontractioii therv '» » gn-ut incrawv of carlmnic acid given ofl' 
<i( nlbvr Udte acid ur some other stibstniitv giving rise to an ncid reiioltun. 
• pvaUr oonmiraptimi of oxygen, though the inereaau b nut equal to the 
inercaM nf rarbonic nvid, but, a» far as wi> can lenrn, no inereflse of niin^ 

During rigor morti* there is n siniihir increiised produelion of nirhorno 
lad and of some ulhfr ucid- producing sttlielaDte. uccM(ii|)iuite<l by a remark* 
■Ut OMivcrwoD of myoeioogen into myoeio, by which tbe ngtdiiy of iht 
iW Ibre u brought abouL 

Thermal Chaugt*. 

I tt. Tbe cbemical cbangce durin)* a eontractivu set free a ijuuititr of 

n, but only a portion .if this eoer^ty appeart in (be " uork done." a nm* 
Ir portion lake* on tbt form of heat. TbouKh we shall hav« her«*ncr 
klnat ibis subject more fully, (lie leailiui; (kcu may be given here. 

Whenever a muscle Diolracts iln teinjwnitiire rixa, indicating thai hwit 
iip^'u iiul. When a mercury- tltenDOnieber ia plungml into a maaii of mus- 
dbb lucb n« tl>Me of tbe ibijih of tlw doff. ■ rbe of the nitfrc-ury is nliKrmt 
lpNilki> muscl«« Wing ibrowo into n prolonged miilnii-timi. More exact 
Mlltt, b«iir«T*r, arc olxuimil by inean:i of a thcriii'miii.-. by tht h*lp of 
■Uik tb« ritv of ifin|>*-mtur« caused br a ft-m repeau-<l linglc coniriictKHW, 
* i ll iiil liy a Mngli- oinlractlon, may be obMrvnl, mid the anioiuit of beat 
fina nut approximately mcainrcd. 

TW tlMnnO]Mle may mniiit either of a linjili' junclion in lh« rorm of a awdlfl 
fAuffd lain tbe aubstaucc of the iniuctr, or of levtral juiiciiuuB riihcr in tbt 
4if« of a Hal surCkce carefully o|>pMed to llie surrai-i.- ot muscle (ibeiHle being 
IMMcvd ao »• to move irilb the r<>iittnctiiig inuRcIc. and thus to keep tn« ctiniact 
■net), or )a tli« «taap« of a IhiQ nr<)j(«. ih« edge of wlilcb coraprininc the aciiisl 
jactHMM. U ibnwl into a maiu i>f musctM and add in poaitioo by ilirm. In stl 
OKI lb« Hrllow-juBctlon or juoutions must be kept at a coostaui lemperature. 

AaolJwr lielliala mMlwd of dfteraiining the cliBiiirea of tempernluTe of ■ Ihsue 
■ haMd oiHKi tli4> nMunrancnl of altera tions in electric reumanci- which a (iii« 
•V*. in contJM-t vitb or plunged into tbe ibauo, ondrrgoca u (he temperature of 
a» timam ehan|tM. 



It has b««n oJeulsUtl that lli« beat given out bv the inuwl«ii of the thigh 
ofn frog in n single cantrnt-tii)!) knitHiiiU Ui 3.1 mifrt>-unibt of heat' f!ir Mich 
frrnmine of tnll3Cl•^ lliv n^ull lieinK' dbuiinM] b): <livii]iiii; by five the UAu\ 
BRintiiit of Itviit givcu utit in tive micct'K'tve finite contracliuDit. It irill, bov- 
vvrr, bo iHtri.-r U> rcKnnl llitw; figiin.-' nf illustmtivc of iht* fnct ihiit tbr hmt 
Kiven out ti coiinmcrablR, riithcr thnn il* diita iSir clnbc>ml« cnlnilaiiiiii«. 
Sloreover. we have no wtiidacUin,' (iiinnlitmive ilcl«trriiiiiiilifnw of ihp heal 
i;iven out by the miwi-lc* of warm -blood ei I ntiiiiinls, though there can !>e do 
<li>ubt that it is much grenter than thai given out by tbe mii«cU'« of the I'rog. 

There cait hanll}* 1k^ imy •luiibc that the heat thus M>t free is the product uf 
chemical ehanges within the rniiscle — elinngcs which, thotigh (hey cannxt for 
tbe reiiBonH given above (^ Hli ) he regarded na simple and direct oxidatioiu, 
vet, since they are procoaees dependent on the antecedent entrance of oxygen 
into the muicle, may be spoken of in general terms aa a ooiubtiHliuD : eo UuU 
the muBcle mny be likened to a Bieam-eagiue, in which tbe cotubuMinn of a 
certain amuiini of material gives riae to the development of euer^y in two 
fornu, as beat and aa movement, there being certain (guautitativt- relntiont 
b«iw«ein tbe amount of energy aet free aa heat and ibat giving ria« to nio^H 
ment. We niual. however, carelVilIy guard ourselree again»t prewin^ **^^| 
nnnl'igr too cluaely. In the steam engine we can dialiugiiish clearly bi'iwe^^ 
tbc! fuel wliich, ibruugh ita i-onibiiMi<in, i.i the ^ilc source of energy, and the 
niachiiK-.ry, which is nut ci>DHUiued to provide miergy, and only wfl^rx near 
nnii ii-ur. In the muscle ne cannot with certainly at nrnent make eucb a 
dittinclion. It may t)e that the (■bimiiciil ohaiigea at tlio bottom of a con- 
Imi'iion do not involve ibc real living mnlcrinr of the librr. hut only tome 
»iib»lnncc muniifactun^d hv tbe living miitcrial and loifgi-d in unmc way. wc 
do Dot know how, in th« living mnterinl. It may be that when a lihre con- 
tracia it i« this niilKitann- vrilhin the fibre which explode^ and nut tbe fibre 
it»elf. If we further suppose that this substance is some complex oouipound 
of carbon and hydrogen, into whivh no nitrogen enters, we ■ball have an 
explanation of the difScuhy referred to above ($6''J), namely, that tiitro- 
geninrs waste is not increased by a contraction. The special ooiitractiie, 
carbon -hydrogen substance, mav then be compared to the charge of a gun, 
the products of its explosion being carbonic and .'tfircolaciii' acitbi, « hilc the 
real living niutennl of the fibri; may be conipun-d lo the gun itwif, but toa 
^n which itm-lf is continually nnd*-i^iing <'hHngv farlK-yimd nH-re wear and 
tvar, among the prnihiclH of which chnnge nitrogcnouH bniiirx likr krcntin 
an- convpicuou*. Thi» view will cortuinly explain whv krealin ir pot 
increii«'il during the cr.ntmclinn, while the carbonic and lactic acid* are. 
Hut it must be rcmi'mhcn-it ihnt wicli n view is not yet proved: it ninr be 
the living tnnurial <>f \hv fibre. n» n wliole, which is continually breaking 
down in nn expii.uivc ihroniposition. and as continually building itself Dp 
again out of ihc nmicrinl supplied by the blood. 

In a steam-engine only a certain amount of the total potential enerj^' of 
the fuel issues as work, the rest being lost as heat, the proportion varying, 
but the work rarely, if ever, exceeding oue-tenib of the total energy, and 
{{^nerally being Icm. In the case of the muscle we are not at present iu a 
pcsition to draw up an exact equation between the latent energy on the o«e 
hand, and tbe two forms of actual energy on the other. We have renson to 
think that lh<- pi-oporlion l>etneen heat and work varies conxiilerablv under 
dil1er4-iit nrcumi'lanct'S, the work .viiiit-iinm ri*iiig nn higti u* nne-fil^ti, itoni^ 
linu-H poi>»ihly »inking na luw an one twenty-fourth of tn<i total energ}' : and 

t llicnurTO-aiiltlieliiiBiuliliKraiiiiiwiir uAtor mlud one (legTM OnlicmW. 


ohMwatiow kcoi to afaow that ihe );reat«r tlie reebtaooe wlikh ilie iuu*c)e 
ham to overconw, llie larger Uie proportion uf the total energy exneiidnl 
wbieb ifMS out as work done. The niuscle, in fact. »eeiiid to be no tor M>]r- 
nyntMia^ that lii« more work it liua tu do tiie greater, within oertaiQ 
U^la^ ii tbe eranomir with whidi it mirksL 

I^tfdjr, il niuM be ren>eu]l<«n-<) that the giving out uf h«at bj- the niuti'le 
h Bot eanfioeil to the oocOAiunii when il U nclitiilly contracting. Wbeii, at a 
laMr MrioH, no trval of tho bent of tbc body gcnenUIy, Gvi(lciK.<o will Iw 
bnMgDt furwonl that lb« niuaeltis, «vi-ti wbrii at. rent, are giving ri««i to Iwtit, 
•o thftt tW bmt giYOO out at a contraction is not some wholly new plHiiion- 
MKwi, but a t4-inporary exaggeration of what is conlinually going on at a 
mon SMble nU\ 

Elettrieal Chan'jt$. 

t M. Braidoi ohemical and tberouil cbaiigea, a remarkable electric cfaango 
ukr« plaop wbsMver a mutcle oontnirtA. 

MtmU-eurrmti'. — If n muscle be rcmovrd iii an onliuary manner from 
tW bidy, mihI two non-polariuiblc eb-ctrndcit,' conii«ctc<l with n delicxtc 
plTanomctor of many convolutions nnd high resistance, bc plncL-d on two 



XoK-FouuusLB ELsnnoon, 

AOtilM* tmbti i.ik> anulcunkifd dBc fllpa eenMctal Mil l> ihvir tQ-r«t4]TC«i1na; t.a,ib« 
■M adfkM* •■'■Una ; M /^ Uk |4iisi4 fUna-otar: (', Itn torUonof (he rtiln>-cli) |iluf teqjeH- 
mimmltm^maal ikviuto; ihUcuibcwMlitnl IntDtOTrwiulntfonn. 

piint* of th« surface of the muscle, a dellection of the galvanometer will 
plftM. iiitlicaiitig iliv exiUenwof a current giaasing through iliu gal- 
from Ihn uJw |HMnt of the muMie to the other, the direction uid 
(if the ilcHrction varying accurdiug to the position of iIh> pcnnta. 
IVe " DiUMlr-curivntA " thuK revealed are seen to the best advimtag*- when 
ijha nuBck ebown i> n cylindrical or prismatic one with parallel fibres, and 
ehm lb« two tcndiiuwis cndi ar« cut off by clean iuciaionn at right luigles to 
tha tottc axi« of the Riu>i-)e. The niusrle then presents a tntnsvcnH; section 
I'anlfleulf at each end and n l()iii!ilu<linitl sur&ceL We may «p«ok of the 
luur as tieioK divideil into two c<ium1 \wris hy an imaginary tmn^crse line 

• n«i CTlt Mn MiM^il •■•enttall;oI*iJlpn(UifindWi<mKi4}nMriMilnG.dl|>|4nCtiilOB aVarafml 
■iMU^araMMllteiv. wlDcb la tnni l> biautlii into (»tui«dton with the Dorm otiDUKtctnr 
•^^ HS Wtm a* MOct or •MiiB4t>r nalMtaeil vllk Bunnal lalliiiQ clilurU* (dIuOui ; It II 
MIMMM (Iw) 1)^ ■<<■>' •■louM bt Uii>iniiKhlr uiul^naM. TliU fiinii ••( «)«oliDd« sIt* iIm m 
M MMlaUOn Uiaii ^ rfinpU |<l*Uiiim "t miirw <*t«l(odW riir <>1>T Bllbrai ■ toaaiKOiUt 
tmmJM. m i>M •nil tiw ikaiu. hIiIpIi ntOttcr mu ob ibc iIhuc iMir !• lelul do br tin Ubdc 
tMbn <t •nr uauM ottdi «nppt« or plaUiuna It Id IM*lf mndcM to tfrrelop ■ omont. 




OB \tB aurfiioe called tbe " eiiiialor," coDinii)iDK all the [toints of tli« nurfiace 
midws}' between Uie Iwo end^ Fig. -il U » iTiajfrauimatii- represenUUtoD of 
such a muwlc the lint! of/ hvlm; the eijuiitor. lu «uch a iuuhU iHa develop- 
ment nf the muidc-i-urn-tiU b> fiiuinl to be aa follovm : 

Tlic grmMvt lU^HfCltciD i.>> (rlntcrreil wlicn iiiiu electrode i* [tlacoil iit tt>S 
mH-poiiit or efjtinlor of th« iiiiiiicic, iinil the o()u-r ■( oithtr cut end ; nod 
the dedection is of »iich » kiml iw Ui xhow llial [lotitire cumnti' are con* 
tinunlly pacing from thf equator ihrnugh the ciilv«noiDe(cr to tbe ctit end ; 
that is to WIT. the cut end m oegntive. rclnttvi.My, to the equator. The cur- 
rents oubdde the muticle mar Im' coiisidenxl as citmpleled by ourreots in the 
munefe frota the cut end tn the equator. In the diagram. Fig. 'M, the arrows 


It ** 


DTiunjkH iLLi-ftainini mi Ei Jx-nuc CXnun* or Knvi *m HtwLK. 

ncliiK I'Unl] •lJiiK"""'<*i'c. « '■"<} wrvE fnca i4Ma (dtbator nmvcorof ipUMElVk oxc*)* IbM Ux 
(mmul* ■! ih* irsiifircw MoUon nnntit l)c uliown la ■mrre. Tbt arron ihovr ih* 4l»cUini or 
the cumnt thraiiRli ili« Rtlnnoiuolor. 

nti Uro oiuiMf- Tlio >lNiiim<iil riirrcrili kr* IIuiM ■hown by Uiv duk ^m, U (Mm d, ■! 
F'jUDilnr, (A > iir lo y «l ibv ctjl viiilg, Tbr cutn-iil rrain <■ lo c ii mmker than fram a to y, (houcli 
bolU, ■* nhowo by Uip arrout, liavi? the mhuc <ILrucUaD- A ontfvTkT [■ hhc>uD f^gm «. ulilob U a^U 
UwwiuMur. tu /, wlilcb la riiiilior rmiii IIih pr|tiaiar Tlwcurninl (In tniwrloi (ruin • total In Um 
ctroiiuIcnnM 10 • iioint n«sn>r the cralrvur ttit inniVDnN «ecUoii li fhmvn al tK Fram a to ho 
t*am I lev. Ibvn u do nunol. wIuUcbIiM b; tbo dotlcd Uo 

indicBte the direction of the ciirrenU. If the one electrode placed al th* 
equator ab, Ihe elfecl ix tli« j>aiui? at whichever of tbe two cut ends, x or y, 
llie other ia placed. If. uito elevtr<ide renmiiiiti|i at the equator, the other be 
ahiAed from the cut etid to n sjiot (c) noaror 1" the eq^iialor, ihe current c"n- 
tioues to have the >ame dirn-tion, but \* of li-s.-< iotciisitv in ]ini|Hirliou to ihe 
neameu of tbe elccimde.i to each other. If thi' Ino efiHclniiltn be plactil at 
nnf<{Ual diatanceii 'f and/), line n:i either «idc of the eijiintor, there itill he 
a ft<i-hle current frimi the one nearer llie cquutor to the one further oA*. and 
ih-' i-urnml will be the fii-lilcr the more nearly ihey arc «i)ui(li«t»nt fr«m tbe 
e<|uiktiir. If they are uuitv equidiaiant — as, lor instance, when one is placed on 
one cut end (jr) and the olher on the other cut end (y)— tliere will be no cui^ 
rent at all. 

If one electrode be placed at llie circumference of the transverse seclion 
and the other at the centre of the transverse section, there will be a ourretil 
through the gntvanomeler from the former to the latter; there irill be a cur- 
rent of similar direction, but of leas intensity, when one elecUode is at tbe 
circumftnence ^g) of the transverse section and the other at 8oiDe point (A) 



liiww r Um Mntn oT Uw tnimr«TBe •ection. In fact, Umj i>ointa which nrc 
wtali>tly DK»l potitivs uwl m<M atpi\i\i- to each other »rv pninl^ mi tho 
■laaMr Bod Um two entrw of the imiiovrnH; HcLton« ; nnd t\v! xMnmty o( 
iMcnrraot Iwtwfwi wijr trro pornti will depen'l on the rcfpcctivr disUiu.'c* 
of tkow points front the c^untor and from thv centre of thp ininaveree 

Asilar currenu may be obserred nhoo the longitudinal surfiioct a not the 
Datanl but an anificinl (^ne: indc«l, tliev mar be wiuiesMd Id even a piece 
of miMcle, provided it be of cylindricof Bhape and coropoaed of parallel 
6 bra. 

Tb«M "roiuclft-ctimalB" an »o4 mere transitorv ourrents. dbaipi>enring 
•a aooo aa the circuit M cloaeil ; on the contrary, tlief last a very c»iiiudfir> 
able lime. They inuM. Iherefoiv, be inaintaiued by tome ehnnjcea ft<noK mi 
in ib« mDfcl»— bv continued chemical action, in fact. They diditpjicnr a» 
tb« irritabilitv of tl>e muscle vnniiibi». and are ooiioecled with tluBie nutritive. 
•(>-<k1I**I vilnl. rhangtt whioh mninliUD th«' irrilithility uf the uiusd<^ 

MMclr-cunrntJi ouch iin have iuM Ih-<-J) dcetcribfd, may, wu repeal, Im- 
nbaamd in any cylindrical oiumic niitably prepared, and similar curreiitJt. 
witb varialkna which need not he diiwuNMtl litre, may b« aeea in miixcUv of 
imiptlar aluipo with obliquely <>r otlii;rwii>c arranj^ed fibreiL And du Iioia> 
BfyBMMMl. to whom dliefly wo ak iadfibted for mir knowlcdgv of ihcw cur- 
fOda, baa been lod to regard Ihoni aji naCDtinl and important pnifn-nire of 
KviBr aitMl^ He has, moreover, ndvanoed the theory that nnucle may be 
WMaml m comimMil of eledro-motivfl porticlca or mokcules, Mcn of 
•hidi, like the niii»cle at large, hiu n positive equator and negative cods, the 
*hcile mueele being made up of thew molticulm in eomcwliat the same way 
(Ut ow an illuAtralioo which must not, however, bo slrnimil or ronsideriKl u 
ID Hact uaej aa a raaxnet may be aupptMed to be mode up of ma^netie par- 
tick* each with ita north and south pole. 

Then aiT rca«noK, however, fur iDinkinn that Uwae mnscle-currenta have 
MHich ftioiUraieiital origin, that they are, in fact, of surface, and, indeed, of. 
tnttdal i>ri);iD. Wiilcut entering into the cuulroversy on thin qu««tlon, 
tkUlowing ini{iorlunt fai;ti> miiv l>e roeniionnl. 
1. Vbcn a muKlc in esamiixsl wliJle it ntitl relainn untnjurwl iiji natural 
tarminatioDR, the cvirrenUi an* miii-h wtmker than when artificial 
•eelioDS have Itven niiuh- ; ihe natural ti-niliiiiiiin end is toM iMin- 
lit than ll>e cut guriMc-. Hut the tdnitiiioii.- end !>i'rama at oneo Motive 
■km it » dippvHl in wnler or nci<l— imU-cd, whi-n il i« in any way injured. 
At la* roughly, in fact, a riiim-Io in ln-»led thv Ii^m evident are t^>: nmiicle- 
qratMa: aad it is maintained that if adequate caro be taken to nutinlain a 
Hsde in an absolutely natural condition, no such currents as those we have 
bndeKribing cxiM at all— llutt nalunj living muscle is itotUdrie, as it ia 

1 The surface of the uninjured inactive' ventricleof the frog's heart, which 
iipnrtically a mass of muscle, b isolectric, no airrent is ubuinod when the 
Jwtrodsn are placed on any two points of the surface. If, however, any 
pn of the surface be injured, or if Uie ventricle be cut acroBso as to expose 
tnit Mirfai.'c, the injured spot or the cuiHirfaeebeooDiesatODoeiaott power- 
bUf Mfpilve toward the uiiinjurml surface, a strong current being developed 
•Istfc fWRt* thniugh the |j;HlvBnoa>elcr from the uninjured surface lo the cut 
mftoa or to the ii)iure<T spot. Tlte negativity thuH developed in a cut 
wfen pHMK ofi* in tite course of aumc houn, but may be restored by making 
tftnb eat aiul eiposing a ttvth surface. 

■ Tlia ncnaMIr at It* iKIiil InMtln will t* «(■ NtMsquwilly. 



The temptnvry duratioo of the ncgstiriiy after injury, »iiH its nae 
opOB freah injury, io the case of ihe ventricle, iii coutraat to the man peiv 
inineDt n«4^[iviiy of injured akek-tal mUBcle, U explained by Ihe diilerenl 
atnivturo of the two kioda of iiiuaole. The cardiac muscle, aa we •ball here- 
nfWrtee, is oontpoeed of ahort fibre-oella; when a cut is mode a oerlaiii uuro- 
her <>f thcae fibre-cells are injured, giving riee to negativity, but the injurv 
done to them iao]m witli ibeio, and is doi ]>ropagated to the oells with which 
ibcy nre iu otiiituct ; beuce ui)uu their death the uegutivity and the current 
<lisnp|H-ur. A friwh cut, involving new cutis, pr<Hluces trtiAx nQ{«tivitv attd 
a new ciirrtint. In the lou^ librcs of the itkulctal niimclc', on [he other hand, 
the eAbct« of thv injury nre ulciwly ]>r(i|uigut(.il tiloug the fibrv from the fpt>l 

Now, tvhcn a mtifcle in cut or injured, thu «ulvtancc of the fibm dies at 
the cut or injured Kurfm^. And nmiiy iihyxinlngivt*. among whom tho oxMt 
prominent is Hertiitnin, hnvi; liccii M by ihv iihorc and ulhrr tact» to the 
conclusion that muflLlc currents do not cxitt nalurally in unloucbed, unin- 
jured muBcIetf, that the muHcular subetanra h naturally, when livinc, 
isoelectric, but that whenever a portion of the muscular substance dtea, it 
becouifD, tvhilf dyiii'j, negative to the living eubetiince. iiud thus givee rice to 
ourreiits. They explain the typical curronis (as I hey might be called) inaiii* 
feM«d by a muscle with a ualural longitudinal surliice aud ariiticiul trans- 
vtsna seotioiis, by the fact that the dying cut ends are negative relatively lo 
the T«#t of ihe muscle. 

Du Buis-Heyuioud and those with bim ofler special explanations of tho 
above facts and of <it her objections which have been urKe<l against the thvory 
of naturally existing electro- imilive moleculea. Into theae wc cannot enter 
here. Wc mu»t rest conlvnt with the atatement that in nu ordinary tauacl* 
currents such ns have been described may be niln^'sscd, but that atronc 
arguments may l)c adduced in favor of the view that these currents are not 
" natural " phenonienn, but ciwcntially of artilicial origin. It will, therefore, 
be lie«[ lo G]>eak of them as currmU vf rest. 

i 67, Currviitt of action. Xri/atiii! I'ariitUon of the miuolc-eurmi(.~-The 
c(introvcrsy whether the " curreui^ of rest" observable in a muscle be tif 
natural origin or not, dow not atiect the Inith or tho importance of ibe fact 
that nn electrical change takes place and a current is devetii|>ed in a muaclc 
whenever it enters into a contraction. When currents of r«t are observable 
in a miwclc, tbtse are found lo undergo a diminution u|Hm the occurrcnoe of 
a contraction, and this diminution is «{iokeii of as " ilie negative variation " 
of the currents of rest. The negative variation may be teen when a miiKle 
is thrown into a ^ugl^ con traction, but is must readily thown when the 
muscle is tvianiuxl. Thus, if a pair of electrodea be placed on a mitscle, 
one at tho iKjunior and the other at or near the transvene section, so that a 
cousidcmhie drflectiou of the galvnuonieter ueedle, indicating a considerable 
current of roit, be gained, the needle of (he galra^»nlt^ter will, when the 
muscle in totaniu-d by an interrupted current mmi through its nerve (at a 
point too l»r from the muscle to allow of any vscRfm of tho current into the 
electrodes connected with ihe gid vuuo meter), swing buck toward zero; it 
Kturua to its original dcHcction when the tctanidng curront is ^ut olf. 

Not only nay this negative variation be shown by llie gBh'anoine4er, but 
it) M well as the current of rest, niiiy be used as a galvanic shock, and *o 
employed to stimulate n muscle, as in tho experiment knuwu aa " the rheo* 
tcopic frog." l''or this pur|>osc the muscles and nerves need to be very irri- 
table and in thoroughly good condition. Two muscle-nerve preparations A 
and B having been made, and each p!ac»l on a gluss plate fur theaake of 
insulation, the nerve of the one U is allowed to fall on the niuaole of the 



Mh«r A in naeh 


of ihe 



Dorve cotiiM in coniaot witli tbe 
» | B» t ar of (bt mtMcU, uni) miutlicr point with one end of the muBcle or with 
• potat «t Utm» diflBncc from (he oiuator. At the moment the nerve is let 
fiul wmI conlart mailr, > cnireni — vir, the " current of rest " of the mnacle 
A — (Mar* ibroaeh (he nerve; thi» nclH na a ittimntuB to the nerve, and m> 
CHBMi ■ mntnicliun in tbe miwcte eonnecte<l with a nerve. Thus, the muscle 
A BCt* a* » b«tU!fy, the completion of the circuit of which by means of ifae 
Dvrre of B ivrvr^ m a itimutua, eauaiiiK the luuftcle B to conlraot. 

If. while the Dcrve of JIH stilt iu «<i>nlact wiih ih« musclenf J, the Oftrre 
of iha tatMt is tetaniied with an inl«rruplcil current, not milir is the muscle 
>'.f .1 ifarown into teunuD, but aim* that nf B, the reason heiuft lu fulluwa: 
Al eadi spasoi of which the loianun of A ia made up. there is a negative 
Tsrialinnoftberonicle^urreiilor^. Kavh negative variation of the raiitck- 
mrrvnt of A servcB w a >limuli» Lo the nerve of B, and u hence the cause of 
m i |— > io the muscle of A; and the stimuli fotlnwin); each other ra]>i(ltv,ns 
Wit^ imduce'l hy the tvtanit* i>f .-1 ihry miu>t d<i, the spaatus in li lu wfii<'h 
thtif giw rwe arv alMi fuiii'd into n tt'liiniia in li. H, in fact, cuntracl« in 
banaocir with A. This csjxTimrnt rhn-Hr. that thi^ negative variation ncootn- 
puijriitg Uw uianus i>f a mtiKic, though it caiiiei odIjt a onzlo Kwinir of the 
gstvBBonMer, Is really made up of a scric» of negative rnriations, each tingle 
B^pttlv* variation corresponding to tbe single mmxam of which the tetnotu 
is RMJa up. 

Hill an circlrical chang« may be manifeiiled even in cases nhcn no ciirr«>t« 
of m\ tfsift. Wo bare stated <§ titi) that the 'iirfnci? of the uninjured inac- 
tive ventricle of the frog's heart is isoelectric, no currents being observed 
mhta the electrodes of a galvanometer arc placed on two points of the sur- 
botk Neveribeleea, a tnuat dblinct current is develo|)e(l whanenr tbe ven- 
tricle omtractsL Tht* may be (liowa eitlier hy tli« Kalvanonieter or by the 
ifcwaco pt c flrea. If the nerve of an irritable musc&nerve pre]>aration tw 
Ud OVCT a puMUing ventricle, each beat i» responded to by a twitch of tbe 
■MBit nf tbe ]>repar«tion. In the eiue <>f onlinary lausolea, too, instances nocur 
In wKiefa It vetm impoKiblci to rceard the electrical change niunifniMd 
doriai; iW contrmctiun as the mere diminution of a preexisting currvnt. 

Acntrdingly. thuar who deny the cxb'tence of " natural " muncle currents 
yak iifa uidscte as ileveloping during a contraction a " currunt of action," 
iiiasiniiul. a« they believe, by tbe muscular sululimcv nx it in entering into 
ika siste of cMntraction becoming negative toward the muscular suUtAUC* 
•Udb it BtttI at rest, or baa returned to a 
M(* nf net. In fact, they regard tbe 
o^pttivtty of muscular sulwtance as char- 
KMrwiic alikeof beginning death uud of a 
kfinniiiic wntraction. So that, in museu- 
br onutrartioo a ware of negativitv, sturt- 
iag fniin the end-plate when indirect, or 
ran the {joint stimulate*! when direct 
ttinolatlon it used, (Huaca along the mus- 
oilat sabftance to the ends or end of tlie 

If. for in*t«iioe, we tupnote two el«ctr>>d«a 
flsml on two ]M>ints (Fie- ^'* ' A and B of 
lUt« about to he slimuTated by a single 
MnctioB-alKick at one itid. &:fbre tne 
idmutati'in the Hhre is tsocleclric, and tbe 

Mnile of the galvanometer dands at leru. At a certain time alW (he 
4fvk haa been sent thmugb the stimulating electrodes (r), as the ware of 

|ria. ». 



OOntraeUon ie tmreUilw down the fibre, iheBecliou of the fibre beneath .i wil 
become neRnlive toward tibe rest of the fibre, and so negiklive touard lh«r jior- 
lion of the fibre under H—i.c, A will be negative relatively lo /i, and 
this will be shown by a deflealion of the needle. A little later B will be 
eiiterinK in lu contraction, and will be beeimihij; iiei;atiTG toward the rut of the 
fibre, incltidin^ the \mn under A. wlitee oefriiciviLy by tins tiniv i* iMMinj; off 
— that u t^i any. B will now be negative towani A, ami ihin will be *nuwn by « 
d«declioti of Uie needle in a direction oppotite tti thut nf thit dtiHrciioii which 
haa juNt previously taken place. Hl-iio-, Imtwcen two el«etmil«v plno(>H along 
n fibre n uugle wavu of c-ontntnlion viill give rice to two cnrrenli> of diKerriit 
phn«c«. b> a <]ipliiMio diange ; and thitt, indrtsl, it finind to be th« ciwc. 

This being ko, it i» obvious that the clectrirni rcault of t^lanizing a mutcle 
when wnvf tttier wave followx along each tibrc is a complex matter ; but it 
it nmintainedtliat the npuurojit negative variutioD of t«tanuscaD be explained 
V til* net mult of a aeriM of ourrentfl of action due to the individual con- 
metioiiE, the second phase of the current in each contraction being l«88 
Durked than the first phase. We ciinnol, hoivever, enter niore fijUf here 
into a discussion of this difiicult subject. 

Whichever view be taken of ihe nature of these muscle-currents, anil of 
tlie electric change during conlrnction. whether we rei^rl that change lu a 
" negative variation," or as a " current of action," it h iiii|>orlant to reruemtier 
tliat it takes place entirely during the latent ]>eriod. It is not in any way 
tlw reault of the dinnge of form, it is the furerunuer of that change of funu. 
Jurt a* a nervous impultw jiaases down the nerve to the niuicle without any 
rbible changes, to a nicile<iular change of Hoine kind, attended by no vtniblc 
cv«nt« kcniwn to u* at prment, but only by au electrical chaug«, rundi along 
ihe muscular fibre from the cnd-phite to the end* of the fibre, prefMiring the 
way for ihe vieihle chungt' of form which is to tuUow. This molecular itivi» 
iblfl change is the work of the latent periixl. and careful obaervftlions have 
shown that it, like the visible contraction which foltom at its heels, travels 
along the fibre from a spot stimulated toward iJie end of the tibrea, in the 
Ibrm of a wav-e having about the same velocity as the contraction, TU., about 
3 metra a eecoud.' 

T^fl Changes in a Xcrv! during Ihe I\tt»a</e of a Xtrvotu Impttte. 

g 68. The change in the form of a niu»clo during itc contraction Ua Ihing 
which can be socl^ and felt; but thr^ chruigoi in n norvu during it» activity 
are invisible and impalpable. Wo :^timulnlo one i^ml of a oorvc going to a 
muscle, and uc see this followed by a cm traction uf (he muscle altat'lied to 
tlie other end ; or we etiiuulnle a nerve still connected ntlh thi.' central ner- 
TOUB ayatem, an<l we sec this followed by certain movenKints. or by other 
tokena which show that disturbances have been set up in the central nervous 
•y«teni. We know, therefore, that some changes or other, ooustituting what 
we have called a nervous impulse, have been propagated along the nerve ; 
but the clinnges are ouch as we cannot see. It ia paeaible, however, to learn 
something about tbem. 

Strveture of a nerve. An ordinary nerve going to a muscle is composed 
of elementary nerve fihrca, luialogous to the elementary muiiicJe Bbree, rnu- 
ning lengthwise nlong the nerve and hound up together by oounectlre tivmea 
carrying blood vcucls and lymphatics. [Fi>!. lift.] Each fibre Is a long ro<l 
or cylinder, varying in diumeicr froni U-ss than '2 ^ t«> 20 *>, or even more, and 

> Iiillw mttMlnoT IM troit : liui. u wrhnTciwri, tinvlns pnitubl; a lilehsr vclodir In tlie Inlacl 
iiuniultui miualM. wlUilu lh« living boiljr. ftiul nryiue ncKinlliig w dttFomitUKM. 



Um MTwml 6brN mrr uriuigvd hj llic codhocUvo tissue into buiidlw or oordti 
■ng *loDg tliv length of th« ti«rv«. A largo n«rvp. micb us thi; scinlii;, 
many conk of varioiu uwm; in such b case the t'^nnevtivc tinue 

(Fib. as. 


II. - iLiii NutviorlUii. IHMuMld.l 
'<<1 Imnnlln' Kk. [iruefM ttom tW f^^' 
- ..iinincciHiUDuoiwwIibtbouidaiitaiMini, 
'IIw MUiUpaUiv-ltoiM nbrlla oT Um vmlimvu- 


r*Bi or t 6lan»Mi Of on at mi. i^i - 1. < 
f. fiMmfllmia. anwIMIni ot ■ nnmtor ol r/ 
•MMBB, t«MtiHlliitolteliil«ttcra(UwliinlFi.i 
« liMeHa tolUHMDu Una* taweni tlx lune-lltinji. 
asB M» tMU cut KiiaM ■• nno pdn« oAan kpicarlns io mibMlli Hut lunrMlbnB with a olrcU of 
■taatitiiMinrtl^MUIiaf Koyuid BtUW. Kuuicluoa DUck! uT oaDOCcUw-Ilana cslliwo «Ui- 
kiMnlia ik( cBdODMUl^ : r. twtlouorsIika>liMHl ) 

krtWMO th« fibm in eadi corcl in niurc dolirule tliun tliut trhivh biodj Uie 

conlt tngetlur: eHch oonl bw n io<irr <>r Iiw» ilixtiiicl ibeuili of ooitDectlv* 

liwK, UM s BiuilAT but MautCT >l>uitlh pnit<.-clii the whole nerve. In smmDer 

BCTTW the oord* ure law ia atimbcj', niiu m vrrr tininll nvrvo inny <'i>nHiiit, to 

to^iwk, «f one corH irnly, ihnt i» to mir, it )iii» one ■•ht^'iith for ihv whi>l« 

■trr* snd fine cnuiivotive lianie binding together all the (ibret within the 

ihaUi. When n large oerre dividn or seoda oS brancbea, one or n>ar« 

ofdi l«va the tnink to form tlie braoob ; when nervea are joined to form a 

(JbtM, one or more cords leavinj; one nerve join another nerve ; it is. as a 

ntioolrwheo averir sioal) nerreiedividin;; neurits end into delicate twigs 

ihlfivMon or brauobing of tlie nerve i.- clTccliiil or owisled by division of 

(kofrre fibea Ifaemaelvea. 

iiulf all the nerve flbrea commsiiiK nn onlinary nerre. Much oi that goiiu; 
(•■naaolv, Ihougfa varying much in lhickn«Rf,hav« thcsiiim' feAturo*, whlcG 
*it K follom: ^eeo under the micrrBcopv In n ]H:rfvcl1y frunb cuadicion, 
■ilkat the nae of any n-iig<-nl«. ivcb Hbrr appvan iw a trniuiparcnt, but 
— iwhsl reft«etiTe. and therofoni brigb^lonkin^. rod, with ii shMqilvib? fined 
Mlliiw. wbii-h I* fbnrai!(<-ristteally double, Ihnt is to mv, the «harplinv which 
■■is the iMilude of tW 6bro is on nicb side uf the fibre ncconiftanied by a 
•nttd UlMplinUlol to iliclf aiid following such gentle curves lu it fthows, 
hliMher iu*arcr thr Kxii> of the fibre. This it ispokeii of as the lioubU eon- 
^^[Fi^. •i7]. Biiit is naturally more oouspicuou*' and niorv easily even in 
ll> '":'■■ ritim ill the thinn-T fibreii. The sub^litnm of the fibre betirMO 
r conioiir linos apnean, in the perlmly ftvsh libre. honiogenMlW. 
U uw tiknt be inu-cd ulong lU eourae for some little distnno- there will be 
taaat intervals an appearancw na if the fibre bad been straiit;!*^'' !>>' a Iig«* 
lue linl tightly round it ; iu IransTerse diameter is mddenly narrowed, 
tal the double contour lost. Uie fibre above and below being united by a 
■smi* »hi.rt isthmus ouly. [Fig. 3H.) This in cnlied ii awU. a ii.xle of Kan- 
nrr. and ugwu exaininatinn it will be found that each Rbrc is markitl regu- 
bth abmg its Im^th l>v nodn* nl interviils of about a roillinietre. If llie 
Un kp vxamtned with ^urthrr am tbero will be teen, or may l>e seen, about 
■iJoay brtweeti every tu-<i dihIw, im oval nucleus lying cmliedded, as it were, 
it ths iwiilin* of the librr', with its long axis itarallel. or nmrlr m>, to the axis 

IlitlUH XKHic-nnaL (UapiUlulKO 

TlilW of Ihvin nn Hm: niiv iif wlilnli 
It rvufttHT, one of mIdillliiiE iMclmta, 

Uilcll, IHo nf whlth lire 'louUecon 
loured. ui<] oiic ullhcniiuoiuoiulnnu.] 

KuiVE-rtMS niuiitVruTioXEavKor KiiiKii. aitib 

ACTIOS or N'mttTi or Sunm. 

■L Hint Conani by ihlokonvd ntamtnnv of tehwu* 

(uoda Of tuttnltfj. •», whiic iidI»iw)c« or sehwim 

rtndKKd iwnrraniK liy flrmrta. rp. Crliiiil«t4Sli, 
mIiIcIi JuiiabciVi.-iiidlnliiH' tbolvnl nC tboaimularM*- 
•tnciliiii ]<r<-ii«tiu tliu tint* n( Fiuiiibuuid ] 




the primitive nhealii, ur newiletnma.^ Lving in the axiit i)f tbiii Hbeflth, nnd 
wmetimai prnjeciinx fur ADnii? <]i»lnn(v innn the torn end cifu fibre, uhctbt^r 
the vboalli b« diHiifuyed or no, niiiy, in JNiniv ciimoi, bu «ocii u dim, nr very 
luiiilly, gmuulRr hitncl or tiiriMid, uboutoiie-thinl or bnlf the diviivicr of tb*, 
fibre ; ibis is the .inVry/ifftr (Fig- 39] ; it Wcom«« 
](»t lo view n:> *Fc trace it bftck to wboro the tibr« a*- 
Eiinies n itoublv cotilour. This nxi»-cyliuder euio! 
rcAdily with ordinary stiiining rvaeents, aod beiof; ia 
this and in ulhtr respects itUied in uature la the 
col] -substance of a leucocyte or lo the muscle-sub- 
slaiicc or a miisciilsr libre, hoa often been spoken of 
ne pi'otop)iisnilc. 

LyioK about Cbo torn ends of the Hbrea mar be soea 
drops or miiiule irrt-gul«r niawtt rumiirkiible for ex* 
bibiiinK' a double contour Hkv that of the uerve-fibni 
itself; and indeed drunt of ihi» double oo»toun-d sub- 
stance niiiy tie *ecii i:>«uiiif: from the torn <<nds of 
ihu fihn* [we Fig. .^"]. Treated with oeniic acid 
thew dn>p« and innsaea are tltiiiK-il hlui^; they net as powerful reducing 
mgeuts, and the rvduced o«niiuai givct the black color. Treated with ether 

1 TMi Irnrd ti fi> lorrr^frii it wit u- ili-ri<iir ilie ooTtiiocEJvc iIhiic iliHtli wnppins round 1h« vbo^ 

nervr. Iikitti'. '. to iiHi»:.i>iirh unnloiiiiu umuiwurmli'niinaini) nmrl- 

lODinuifiit lU' 1. aiialiiay.aml l»'ii-i; iiviirlltinau Unonnxd (brthalnui of 

UKnnruuMii . 1. 1 ^ . i^ lo Ibe Mnxil«iusui lu miUEic, til., Uw ibcuU of llw Stuc- 

buQiuM or SrarcTnax i^r 

UlM'lUTKII linviM-iiui*, 

I. !<i«nlclnlDB nr ■tintli 

ofMivMitt. £. Mnlullaty 

■htaUl. ^ AilMTUndcrl 



or oUmt aolreoiB of fal tbejF moreoTer tnoiv or less rHidiiT diswrlve. Olf 
viontljr Ik*; «» Urgeir conipcwd of fat. and we aliall ee« t'tiat the fat com- 
ptmuta tbeoi it of a very eomplex itature. Now a itei^'e-Kbiv ahowJDg a 
double contour Mains black with u>n)ic acvi ; but the MainJoi.' is abeent or 
T«rT tlt);)ii wlter« th« doubb couioiir eeibiM tw at u turn end nr at the Dodm 
vf kanrier: llie axidojrlinder utainii wry slighily iiidei'd with uamic acid 
•ad the abealh hanlly at all. Su, nUa, whi-u a trannvfrM: Mii-tion la made 
ihrounfaa ttfrvt or aiwrvvoonl.each librc nppmra i» K-cliooaou dark black 
riog MrroundiDg a niui-h nwre fiiinllj rtninccl ceoErnl nrctt. Furlhrr. when 
a (loabl* cualoiirvd nrrvr-libn- i* tn'^tiwl with clhrr. or other tolvciiln nf t'lit. 
tbrfluobUconloiit vntii«h«^«. and tht- whole tihrc become* more lritnit|)(in-»l : 
Mnt\ if lurh a tibrv, either before or aft" r the trcnimctitwith ether, U'Miiincd 
■ itb oarmtne or oth«r dye. the axis-<-y1iiK)er will hv seen nt n nninnl Itaiid 
or ihmd lying in the axis of n tulHitar upace dolincd by the tinarilemmn 
wbicb atain* only sliKbllj except at and around the oiiclci. nhich. iis we 
hse* atan. an embodued in it at inicrvnl». In tlie entire lihro the lubiilnr 
MBcw between tbeaxM-cylindcr and the slieaih is filled nilh a fnltr material, 
lae mrtluUa, wbirh. Tram its fatty nature, bm Huch n refritctive power ns to 
iliit a ilonble contour when aeeo with Iranaiuilted ltf[bt. on which account 
6tirr ii«elfhn» a double oonlour. It islhi* refractive power of t lie medulla 
b Kirea to a nerve-fibre and atill more ao to a biiuale of i>en,'e-fibre« or 
ta a wkoJe nerve a characteriMic opaque white color when viewed bv rellecleil 

At we shall we, all nerve-fibre* do not iioeoew a medulla, an<l hence euch 
■ Hire aa we are describing it cadled a meaiti/aUd fibre. 
X iJP***^ luedullaied fibre conaitt*, then, of the fullowinK parte: 
1. tie a/w-4'yit4'/rr, a central cylindriciil oofvof eo-oallen "prolopiaaraic" 
■U«ria), (Mime in nature, and readily utidctKoing diange, soroeliinm swel- 
lia|««l.^>ni>'iim<««hrink!iit;. and hence in various fpecinien^ appearing now 
vilkick baud, iiuw as a ihin Mreak in the axis of the tubular gheath. and 
cMig fal enm McUoq aonetinwe a circular, somctiines an oval, and not un- 
nqimdjr a quite irre^lar outline. Probably in a perfectly natural con- 
mi it oecapiee about one-half the diameter of the nerve, but even ile 
auii] mte varies in different nerve-flbreo. Witen teen <|uiie fresh it has 
■iaply a dim cloudy, or, at most, a faintly Kranular apjiearance : under the 
■Mtnoeof resK^nta it ia apt to become fihrillated lonffitudiually, and has 
^naiippoaed to be in reality <^(>IU)MM7d of a uuniber of delicate longitudinal 
ftrilbe united by an interflbrillur tulMtance. but thii is not certain. It b 
knhn Mid to be prote«l«d on ii> ciiii>ide by a truuxpareui sheath, the axis- 
rrliniler theath. but tliis alf) in divputnl. 

Tbt axi»-cyliti>k'r jimmisi uubmken thrmiiih luiccewivc nodes of Itanvier, 
lh»r>«ttrictKHiof the node nut afTectiuK it othcrwiM) than iierbajM to narrow 
il Now the fibiesof a Npiiuil nerve I omitting for the pmeut the libres 
■■in frutn the *yni|)«ith«-t)c nerves) may be trni-ed bock «ithvr to the spinal 
pmHno on the |iu>(f rior root, or along the anterior riKit t» the anterior 
WMa of the •(linal con) ; nnd.nn weaball aeo, the uxi«-cyHndcr« nf the fibm 
m, ia butli <■«<«■»'. prulongaiions oi" procrasee of nerv«-cclli', in the former 
MHufoelUof ih<- ganglion, in the latter ciwe of cells of the anterior ooraua. 
b ikIi ease a DnxHvi of a cell W-oming the axii-crlindcr of a nerve-fibre 
nm an unbroKi-n coiirM^ pasaos as n continuous band of [leculiar living 
MUrr, through node uflcr node right down to tho termination of the fibre tu 
Ur iMcie in which the fibre ends ; tlie only obvious change which it under- 
^ il that, in many if not nil c:k<e«, it divides near its lerniiRatioii in ibo 
taaw^ and in eoinc canes the divisions are numerous, and jo\a or anaMtoraoaa 
ftMlf- Obviously the axia-cylinder ti the easential |>art of the nerve-fibi^ 



'2. Th« primitive ^tvath or tKurilemma. a tubular jtheaih of tnuupnreiiL 
appareatljr bomogeooou* niiitoml, not unliki- that iirnmrculeniniK iu iiitltirv. 
At eavh ni)dc the DvuriloiDinti i« ccitixtrictivl »o m lo ■■lubrtoc th« iixu-cylin- 
<)er cIomIj-, but is nt the vune tirno thickrnivl by »nmc kind of ocnic&t luate- 
riiil. StiiinitiB rca^iibi. wpeciiilly silver nitrntc, nppcnr lo enter tbc nerve 
libru fnim without more n-Atlily al a nude than elsewhere, itnining lb«- libre 
tiutH n( ihe Dode, and creepio); upward nnd downwnn) from the ixxli; iilimg 
tbc axis-cjlind«r ; hence il hns beeu ituppirised that the uiitritive flui<l. ibe 
lymph, oncora into the fibn i: ! - < (^ts access to the 8St§>eTlini[er more 
rcttiiily Rt tlie nodes than >!- i-.h- AImuI midnay lielween every two 

nodes is plac«<l a Ion)* oval mn {■ n-. <iti the imide of the ueurilentran, pushing 
the medulla, aa il wen;, inminl. ual so lyiiiK in a shallow bay of that siih- 
Slsoce. Immediately surroundiu); the nucleui> h u thin layer of t;ranular 
subetanoe of the kind which we havo ii[H}ken uf aa undifTerentiated proto- 
plasm : in young newly fornKil librc at all eveiiU and iKMnibly in all fibres 
a very lliin lny<ir of tliis aamc 8ub«lance lit continued all over the aegment 
between tbo iio(Uv, on the inner snrfacc of tlic nenrili'mma between it aud 
the medulla. 

3. TV nifjUtUa. This ia a hollow cylinder of fatty material of a peculiar 
nature filling alt the space between the neurilemma on the outside and the 
axis-cylinder within, and suddenly ccasin^^ nl each node. It thus fomn a 
close htting hollow Jacket for the asis-eyliuder between every two nodes. 
The fatty malerial is lluid. nt least at the temperature of Ihe body, but 
appears (o be held in its place as il were by a network of a stibstano- called 
neurokenMlin, allied to the siibtttanco herutia, which is the basis of the bomj 
scales of the epidermis and of other horny structures ; this network i* most 
marked toward the outaiile of the mediilln. 

8o long aa ibe nerre in in a frenh living, perfectly normal condition, the 
medulla appcnrs smooth and continuous, showing no mark* l>eyund the double 
contour; but in nerves removed from the body forcxaminntton (and accord- 
ing to SDuio observere, at times in nerves stifl within the bmly) clefts make 
iheir appeHrance in the medulla running obli'jiioly innan) Irom lJi« neuri- 
lemma to the axis-cylinder, and freanently splitting up the medulla in lueh 
a way that it appears to lie composeo of a number of hollow con«s [Hirtially 
slid one over the other along the axis-cylinder. These clefts are spoken gf 
as indealationM, At a later stage of alteration the medulla may divide into 
a number of small irrei-iilar ina^eti separated by floid ; and since ea«'h small 
pieee thus Hoparatt-d haa a double contmir. like a drop of medulla exnded 
from the euil nf a Ittire, the whole tihre baa au irregular " curdy" appearance. 

The esaeutiai pun tbuii i>f n medullateil nerve fibre (of a spinal nerve) is 
the axis-cylindiT, which is really n ^irobugaliou of a procea* fh>m a nerve 
cell in a apiual eunglion or in the spinal mnl, running au uubrokeai course 
through ncidi: nuer node, never in it» cour*i% a» far as we know, joining 
aoother axis-cylinder nnd very rarely dividing until it upproaeties its end, 
where it may divide freely, the diviBions in sunn; casej" annstomoaiui; freely. 
We may conclude, and al I we know sup|iurU the concltisioo, that the changee, 
making up what we have called a nervous impulse, take place, primarily aud 
chiolly nt all events, in this essential part of the nerve fibre, tlH-axis-cvlinder. 
The ucurilemma and medulla together form a wrapping fbr the nourishment 
and protection of the axis-cylinder, tJie fatty medulla probably serving 
partly as pn>]>ared ftiod for the ax 'is-cy Under, partly as a mechanical sup- 
port; possibly it may also play a part aa an insulator iu tlie electric phe- 

It is eamy moreover to see tbnt while the axis-cylinder along its whole 
Icugth is practically t^whatever \nt the exact manner of its funualion in the 


vo> m i»n of the eall of whii^ it is ma vlongUwl pfocnii mch nocment 
ttrn txrre two nodes rrprcwnls a cell wrnpping rouiid the iuct*crTiii(liir 
rtiw, i>r wfiicb D)-ll the nucleii* brtwcvu thv tradu is the ODcIeiu, llio n«u- 
I riWmiD* ihr mivcIom or cell irslt, and (though this a mrhupe not ijuitu to 
\damr) the iiifdHlU iW c«ll suMmiice Iu^It converted into tatty tnaleria), a 
n*ll in tut wbiob it raiUf uiitfide the axis-cyliiidcr or nerve libiv pro|>er. 
It u alaoy the ftxi»«yUod«r that the uervoiis impul^ei sneep. and each wrap- 
pinjt rrll only serves to noumb and protect the seumeut of the axuKtylinder 
bp|<B««v iia two nodea. And we acrordinftly 6»d that both Mt the beginniug 
nf the aerre 6bK in the ganKlion '«n or ^pianl cord, and at its end in the 
. h<iUi neurilemuia and medulla dlsajijienr, the axi^cylinder only heiujt 


A nem soing to a muael« is chJvtly (x)tii|iuiH!d of iiiedii Haled Gbrw aa juiit 
HIhmI. the uinjority at which, i-:idiug in cud-plnl«s in the rauaculnr tlbres, 
atv the fibres which cuoducl thi* nefvouN iiii|MilwM to the mtiitcle, cniuin;; it 
to eoauact. aiul ma^ haDn be»pokcii of a» awtor nerve fibrcH. Some of the 
Cbttv however cu<l tn other partx, such n» the lendoD, or the ci>iiiiectivc Um- 
•os between the bundlw. and mme in tbo bloodvcstels. There are rcnsoni* 
for thinking that lonio of tbvef ccinvey impiil«s from the muscle to tho ccn> 
timl aerrous system and an consequently Rpokcn of as sensory or afffrenl 
ftbns. conoeming tboee connected with the bloodvoMels ne sball speak io 
iMiu with the rsseuiar ayaUm. 

t tm. \errr-enitinyt in ttrialfd mttmitar /ibrtt. A nerve on eoieiiDg a 
BMcle divides into n number of hrancfaee which, runnins in the conneeUve 
IMW of the muscle, form a plesua rotmd the bundles of muscle 6bres, tlie 
tsaller branches forming; a plexus round lite muscle fibrw ihemselves. 
Fma this plesua are given off a nund>er of nerve fibres, runnini; ainj^ly, 
wkef which Joinings niiude fibre eiiilf in an cnd-pl&tv. In furniinj^ these 
[hniH ihr irxlividiiiil nt-rvi' libra* divide rejHTiili'dly, the diviiii»n ulwny* 
tikfait plofv at a niHt<! of Kanvier, so lliul wlial in it xinglct nerv*-' tihn: iii> tuc 
SSTintrn the muK-lc may give rise to sovomi tu-rvo lihnv ending in wve- 
hImbmIc fibm. Tlie tier\'c fibre joins the niiiscto fibre n*- about its middle 
trniaewfaat nearer one end, and occasionally two nerve librM may join one 
nH* fibn- and form two efld-plales. The gonvml distribution of the bun- 
fc <if n«rve fibtvs and single nerve fibres is eueh that some portion of the 
■Mtin is left fVee frufl) nerve 6bres; thus at the lower and at the upper end 
■'lb Mrtorins of the frog there is a portion of muscle quite tree from tterve 

X mi)[k nerve fibre, ninniuf; by itself, has, outside (be neurilemma an 
iHiiuiwil delicate «heath of Rn« connective tissue known as UenW* Aet^h. 
sUcfc nnpeara to be a continuation of the connective tisuie forming the 
iksih (if ike nerve branch from which the fibre spraii||C, or uniting the fibres 
tvohcr in the branch. 

The actual ending of llie nerve fibre in the muscle fibre dtflbrs in different 
dHBW of animals. 

la nammals and some Dth<>r animals the nngle nerve fibre Joins the nius* 
difbn in a iwelUng or projectiufi having a more or Icat oval btuic, and 

rwtng wliea seea iid«mys as a low conical or nmndeil cminenoc. At 
Minmit of this eninaoce the nerve fibre Wot both iu slivuth of Ueiile 
nk il» neurilemma, ono or other or Imth (for on this point observers do Dot 
•PfeJ becoming continuous with the sarrolemma of the muscle fibre. At 
tb wnaiBit of the eminence, where the shcutlis fuse, ihe fibre, now coiwiattng 
«ly uf nxi«-cytindcr and medulla, loees its medulla abruptly < in Ihe mus- 
chs of the lon^'ue the nerve' fibre in many caeca Uxtee its medulla at sotne 
qaiiderahle distance before it joins the muscle fibre to form the end-plnte). 



while llic axin-eyliTiiler liranc-fac* out in all dir«rtiom, lite Monwivliiil vni 
briiiiclitv, whicli wiini^liiiKW niiiivtonxBU!, forming a li>w roniuHl niiMi, tr. _ 
whiMi viewbi fruiu abnvn hiui nn BrhorcMci'-tit »r labyrinthinr niiiM-nrann:. 
Ou ilw brnDchm of this aborwccnco mny lie unc or more somcwhai sriinulBr 
ftvnl" iiiiclci. The nborcsccncc ilsclC hns. like the nxw-cylindcr of which it b 
II lUvciopmeut, a vita* taiotlv granulsr or cloudy anpenninoc, hut lying hv- 
twwti it niid the iictiial muscle aubstftticB is n disc or bed of »om«Kh4il 
coaraely granular inBterial, called the lole of the end-plate, on which lh« 
romilied arbcire«ceiit axi^cylinder rests, more or leas overlapping it at the 
edge, but with which it appears not to be actually continuous. Lying in 
the iiiidat of this " sole " are a uuniber of dear oval transparent nuclei. 

The end-plate theo beaoaib the sarcolemma consUta of two parU, the rami- 
Bed axis-cylinder, and the granular nucleated a»le, the two apgmreutly, 
thmigh iu juxlapMition. imt heiDg ■.■»ntiniiini#. Accunllngtu t>onie obsen'en 
the Vile In conliuuoii^ with and indeeil is a sjiecinliztHl part nf that substance 
pervadins the whnl« muitnilnr fibre which we spoke of nn iutnrnbrillar sub- 
ttatic& W« cnnnol eiiliT here into a diMCUwion of the jtrolinblc mfniti»){ auil 
UM of tb(«(' iilnictiirce or how ihry cfTect what xccm* obviouKly their Itinc* 
lion, ihe trani> format ion of the chanpw constituting u nervoun impulw into 
the changes, which running along the muscle libro in the latent period a* 
fur^runners of the changes cnlniliDg actual contraction, may bu »nokvn of as 
cou>liluting a muscle impulse. It is of inlereet to obwrvc ttiat orrtain 
analogies may bo drawn between an end-plnle and the histological elen»cnt> 
of the so-called electrical organs of certain animals. The element of the 
electric organ of the torpedo, for instance, may be regarded as a muscle 
fibre in which the nerve ending haa become highly developed, while the 
muscle substance has been arrested in ita development and lia-t not become 

In amphibia (f. ;/., in fVogs) the ending nf a ner\-e fibre in a inttacle fibre 
b Mntro'hnt ililTcrcnl- A nerve fihrp about to end in a muicle flhr« dirtdea 
into a hruch of several nerve tibrcs, r«ch of which, losing it* xheath of 
Benle aod sarcolomma. enters th« same inusclo fibre, and ihcn Iiwing il* ni^ 
flnlU runs longitudinally along the 6brc for vome distano^, it and its branebt* 
dividing several times in a chnrncteHslicnlty tbrkcil manner, and Iwafiilg U 
iniervats oval nuclei. In other animnlfi fi'rms of nt-rve ending an* met with 
more or lees intermediate between thiit seen in the mammal and that Mtcn in 
the frog. 

S 70. llesides the medullated nerve fibres described in S 6i!, thont are In 
ini^l nerves going to muscles a few and in some nerves, going to other parts, 
a large number of nerve fibres which do not possess a nieilulln, and hi.^nce ore 
culled •ton-meilit!tateii ttl/rai : these are ce^iecially abundant in ihe so called 
syin)>iaihetic nervuH. 

A nou-medullated fibre which, like a medullaled llbre, may have any 
diameter from '2 ^ or Icki to 20 " or more, i» practically a naked axi^-crliiider. 
not coverr<l with medullu, but liearing on it.i outside at iuten'aU oval nuclei 
diapoied loiiiritudinally. Theso nuclei appmr wholly analuguus lo tlie nuclei 
of tlw neiiriieninia or n raedullattHi fibrv, and proliably belong to a aheaih 
enclosing eacli fibre, though it is not uiwy to denion«lmt« the independent 
existence of such a sheath in the case of n»o« ooii-mwlullated fibres. In 
the similar fibres constituting (he olfactory' nerve a sheath in i]uitt.' oonspicti- 
ous. Unlike the medullaicd fibres these non-mo()ullatod divide and alw join 
freely: like them eaob may be regarded as a proecw of a nerve ocll. 

Of such non-raedullated fibivs a scanty number are found in ncrvca g<Miig 
to muKlee acatlered anion^ the medullate<l fibres and bound up with then 
bj eonneotire tissue. They appear to have uo connection with llw muaculw 




fibns, bat to be dUiribuivil clii«Hv tn tbe bloudfesMl* : mkI lh« ftincliou of 
wa-SMlBlliutl (ilinv hid beller m coDiidtied in coDn«*:ti<Ki iritli n«rve<i nf 
vbidl tbtjr fonn » Inn;* pun. Mich m certuin nerve* goiog to bluwhwwU 
aod lo Mcntil^ QrgWM. But it miiy W iiUt^il thnt though thej piwvtM DO 
awdalia ibtj sr* capable of pri>|>iigiaiag uorvuiw iinpulvu* in thv sumo way 
■» Ottdalklcd nurvw: uiti (bU Tact iniij be taken u inilknting tliiit llii* 
Bvdalla caMDOt serve uiy vcn- important function m an vlectriv insiiUt^ir. 

t 71. TA< rJiemiMry of« »enf. We havo apoken of tfa« lovilullii ne iHtiy, 
and }Tt it in in reality vcrr largely compoaed of asubatanoe which ia nui )in 
tbv Mriet mwe of the won!) a lat. When wocxiimiDechernicollF a 'juaniity 
otttmrrt (or wbat la practically the Bame thing, a (tuauiilv uf thai jwit of tbe 
nrntnU nervmia BystetD uhicb b called uiiilf mailer, and which as we shall 
an i» duaflv cmnpoeed, like a nerve, of niedullaled nerves, luid is to be pre- 
fcrrad far cotntcal exaininatiuo b«(.-uuK it cootainB a relatively l^InaII (|uantity 
of omMCtirv tiauie), we find that a very large proportion, acoordiiiE to some 
•banvn about half, of tbe dried matter «onsista of the peculiar bmly. 
flAal(«(«riM. Now, cboteateriu it not a fat but an alcohol; like glycerin, faow- 
•W, which i* at*u an ulcobol, it fornw ciom(Hiiiiiii> with fativ nriil*; lutd 
ihMgll we do not kn<>n ilHinitrly the cbcniicnl ivniilition in which vhulvtittrin 
txbla daring life in Ihc nH-diiUa. it i* iiiorr than ]ir<>l>iil>k' that it ex'au in 
MM* eonbitiation with aoiae of the really latty bodic* also prownt in thv 
■(daibi, and not in a Am mlatcd rtntc. It i* >iDgtibir ihat liotiiti.'v being 
in Mcb large <|uanlitica in ncrvoua tisHio, and to a small extent in 
Ikmca and in blood, cholcstorio is a normal constituent of biU-, and 

tthagrcMer partof gall-Monea when th«wan preocol; in galUtonea it 
* ttadoabudly preaent in a free suio. B«Nd«s dioleet«rio " while " nervous 
aailer cuntaim a leaa but still coneiderabte t^iiauiiiy of a complex fat. wbtise 
Man ia dbpnicd. According to ftumc authoritiee rather lau than half (hi* 
iMplii &l matint of the peculiar body (eriihrn, vrhioli we have already 
«tt la ba praMDt abu in bloutl curpusolo and in muacle. Lecithin contains 
ititKliela of elaaric acid (or of oldc, or of jMliiiide octd) aMoelatcd tiot. as 
iimfiaarr 6tU, with aimnlc glycerin, but witlt the more complex glycerin- 
(btphuric acid, and fiirttier combined with a nitrogenous body. »riirin, an 
■aawaia cumpound of some eonsidi'mhlv cumplexity; il is tbercfora of 
iHarkablr nature, sinoi!. though n fnl, it conlniiis bulh nitrogen and phns- 
tiana. Acoording to the laina aullioritits the rcmaindec of thr complex 
■leMiiMa of another fattv body, also apparently containing nitrogKii but 
hi lAosphonia, called etrtbrin. Other anthorilics regard both these bodice, 
Imtkia and cerebrin, as products of decomnosition of n slill more complex 
bl. failed pfwtayoM. Obvionaly the tal of the whitr mntler of the central 
Mftoas syMcffl and of spinal nerves (of which fat by far the greater part 
as« asi* in the a>edulla, and form nearly the whole of tJie medulla) is a 
my tnmplex body indeed, apecially so if the cholesterin exists in coiubiiia- 
lica «ttb the Ici-itliio, or cerebrin (.or prolacon). Being so complex il ia 
sttatally very uiiMoble, and indeed, in its instability resembW j^roteiil 
■BUar. Hence, prubahlr. tbe reason nhy the medulla obaogee so raindly 
ad to profocindly aller llie drnth of the nerve. It Mciua. moreover, that a 
cmain ihuugh otinill i|uautity of proit-id matter forme part of the medulla, 
•4 )l M puwihte that iht* rxists in aoinc kind of combinalioD with tbe ouiu- 
fln bt : bnt our knunleilge nn this point is inii«rfeLl. 

Tba pcvcDOv in such large •(uamily I'f thi» complex futty medulla render* 
iksebsnieal examinali^m of the olhvr con-ititueiitv uf a iterve very difficult, 
lai «ur knowledge of the chemical nature of, and of the chemiial ehangra 
pianon in the axis-cylinder, is very limited. Kxaiiiint-il undvr thi.- micnj- 
w^ the axia-eyllnder gives ibe xaothopniUio reaction ami otlier iiMlicatious 



thai it is proteiit in nature ; beyond thu< we nre lurgelr confinetl lo inf 
W« infer that ile eheniical niilLire im in a ^n^ral way ^milur to ibai of 
oell Klbetonoe of th« uerre <.-ell of irhicli it is a proceai. \\\- iufi^r llial th» 
chemical nature of the cell imbalance ut' a nerve all, heingof lh<f kind ithifili 
iit fr«i]ueally called " prutoptasmic." is, in a general way, mtnilnr lu that of 
other "proloplouuic" eelU, fi>r tiialiiuue of a leucocyb:. Now wbcrt^ wo rao 
rxnmint: convenientir such celli we find, ati we hare uid ID $ -lO, thv nrotvidt 
pmeiit in them to nc M>ine form of albumin, m>me form of elobulin, aod 
either niyonii itiwif, or niiit- wdiTnix of myoBiii. or maic allied boav. Id otli«r 
words, tbo prolcid hiwiii of tlie kind of cell aubitlaiicc which is frmguently 
spokeD of as " imd>t)Vrvntiat«id [>roloplii»m," does not. ia its broad feature*, 
differ inntcrinlly from the pnitvid tia«is of thut " diftcrcnliatcd proioplasm " 
whii'li we linvi- cnllcd tmimile siihstaniT. Hpdcc we infer ibnt in their broad 
chonii<^'aI featiireii the axis cylinder of a nrrvo librc and the cell iKxIy of a 
nerve cell resemble the substanre of n mmcic fibre; and this view b sup- 
ported by the fact that both )cr«»lin and lactic acid are present as "e:x- 
traotivee," certainly in the central nervous system, attd pronably in nerrea. 
The reaeniblancc is, of conrvo, only a funeral one; there must be ditloreiicca 
in eberoieal nature between the asi^eylitider which propagates a iiervotu 
impulse without cliange of outward liirm, and the muscle 6bre which oon* 
liaela; but we eanuot at prcDeiit aiate exactly what these difference* really 

After tlie fats of the medulla (and the much amaller quautltv of bt 
[iroent in the axiit-eyliuder), the protelds of the axit-eylinder, and ifie oibei 
soluble subatuDcea preiienl in one or the other, or gathered round the nuclei 
oftfae neurilemma, have by variouH inctuia beendisolveduutof a ni^rvvlibre, 
certain substances still remain. Oueof tb<fleinsaiaIlc|Liiuit)tyisthe nuclein 
of the nuclei ; another in larger r|uaiility '» ihe substance nnmJ)emtiti which 
forms, as wc have sovii, a supporting framework for the medulla, and whose 
moat marke<l charact«riitic is, perhnpt, il4 mixtimee to iolution. 

In the ash of nerves there is a prepcinderaiico of potaasiuiu salts and phot- 
phatei», but not so marked ne in the case of muscle. 

Ji 72. 7'/te nermu* impwlte. The chemical analogy between the aubstauoa 
of the mtieole and that of the axis-cylinder wuulil naturally lead up to (tip- 
poae that the progrew of a nervoua impulse along a nerre fibre was 
acooinjianieil by chemical cbungei^ similar to those taking place in a iniiad* 
fibre. Whatever changes, however, do or tuny take place are too slight to 
be recuguiy«(l by the means ut our (li»p<)e>iil. We have no satfafactory 
evidence thut in a nen'e oven n.-pe'jited nervous impuKii can gi\-e rise lo an 
lU'id reaction, or that the dt-alh of a nerve libn; leuda to such a reaction. 
The ifniy matter of the central nerv><>us -^ is true, is said to be slightly 
ucid during life and to tieconie ni»n- acid oAer death ; but in this gray matter, 
nerro cells are relatively abundant; the white matter, compoeed chiefly of 
nerre fibres, is and remains, during action as well as rat, and even after 
ikiatb. neutral or ulighily alkaline. 

Nor have we iiali* factory evidence that the progras of a nervous Impuba 
is accompanied by any setting free of energy in the form of heat. 

In fact, l>eyond the terminal results, such as a muscular contraction in the 
case of a nerve going to a muscle, or soma affection of the central uervoiit 
system in the cose of a nerve still in connection with its nervous centre, 
Uier« is one event and one event only which we are able lo reoogiiixe as the 
objective token of a nervous impulse, and that is an electric change. For a 
piece of nerve removed from the body exhibits nearly the same electric 
pbsDOTOCoa as a pieoe of muscle. It baa an equator whidi is electrically 
pMgliv« rslaliTcly to the two cut ends- lu fact, the dJagnm Fig. 84, and 


ilk* dnoiptioD which waa siveD in $ 6<1 of tbe el«ctrio change* in mtucle 
mmj Ui applied bIrkmI u well to a nerve, except that the currents are in all 
cBMt anirb roun- (evMv In the caie of nerrea thanofmiMcleB, and the ipecial 
mrrvata IVani tlm circatattreaix to the centre i>f the iransvene sections 
cBaout wll In' nhoKU iii a sletider nen'e; indceil, it is ilouhifiil if ihev exist 
at a!i. 

During thv iMfMgo of a uervouit impubu the "iiuiunil iierro-vurreot" 
I nrinUivo varintitiii, junl a* llw " iintumi niuwle iiurri-nl " iiiidor- 

■ a nigatiii variali"ii iluriii^ a cuotrnction. Thom iirc, moreover, naMnii 
Um cwa of the DUtc, an in iht raMi of tin- inunclr, which li^ul uk to douht 

lb« prafxIstenM uf any «uch " imturnl " currcntx. A ntrvo in nn nlwoliicvly 
lutarml niaditinti ap|>mrF to be. like a muflclc, iwKlvclHc ; hoiicr ne may say 
that is a anxr (hiring llic jinwaige of a nervous impulso, as in a muscle 
dsrina a muK-ular contmclion, a " ciirrcDt of action " ia developed. 

^'tw " current of aclioo " or " itcgnlivc vnnation " may be shoim either 
bv tht icalvaiHMnetcr or br the rhewcopic frog. If the nerve of I lie " muscle 
avm pmMralioD," Jl (tee § ti7> be placed in an npproprinte manner (m a 
llM*«aglify irrilalileuerve, J (to shicn. of course, DO luuscte Deed t>e aiuiched), 
M»eUag for instance the equator and one end of ilie nerve, tlien siueU 
tadwtioo-aliocks sent into the ftr end i-f A will cause sioffle Hpiutuia in llic 
tmsrlf of //, whil<r leiniiixation of A, i.e., rapidly ni|>oated thocks »ent into 
A. will cause ti-uiiiin of the muscle of B. 

Hiat lilt* <iirr«iii, nhdhrr it be regarded ait au iudc)i«Hdeiil " current of 

Mliso ** or as a iiejjativi' vBrmli<in nf a" prMxisting" current, ts nn nwrntial 

latiirr of a nrrvoiu inipulM; i!< »lion'n by the fact that the degree or intensitv 

tf Ih* one vnri<-» milh iliut of the other. They l»olh truvcl, loii. at the Htine 

an. In da>cribing tlifl muscle -curve, ami the niclho<l of measuring the 

■SK»br lalmt [wnod. ire have incidcDlally shown (^ ■lli) bow at the aame 

tas the velocity of the oervoue impulse may be measured, and staled (hat 

lis rale ill tbe nerves of a fru); b about IJ^S meters per second. By means of a 

•pnil snd Mrocnhat complicated apparatus it is ascertained that tlte current 

■f (rtiiai travels aIoD)( au iwlatc^l piece of nerve at the same rate. It also. 

likrtW nwleciilar choose in a muscle precedioK the coutntcuon, and indfed 

iW conlradion itself, traveb in the form of u wave, risiiifc rupidlv to a 

am at each [loiiit uf the nerve and then morc)j;rHdiiiilly declininB 

Tlw length of the wave may by speciul mcjiiis be measured, and is 

laul III br about IM mm. 

ITIvn an irtilaied piece of itcn-e i* .^timuluied iu the middle, lb? oiirrcnl 

ittiti'a i* |>n>|>af(aied (Kfually ncll in liulh ilinictioiia, and that whether the 

r Ilea cliieflyaBDMnror a cliiefly motor nerve, or iiide<-d if il he a ncrve- 

OQUpaised excloiivwy of motor or ofuauury (ibrcn. Tnkiii); the curroiK 

«f acftinn as the lok(.'n of a iirrvous impulxc, we infer from this that when n 

flbr« ia BtiniuUti'd artiticially at any juirt of il« course, the nervous 

going Irnvvls in both direction)^ 

naeil jost DO«r the phrase " tclanizntion of a nerve," meaning the 

^pUaAioD to a n^Tve of rapidly repeated shocks nieli as ironid pr<iduc« 

tAtmt in tbe muscle to which the nerve was attachiil, and we shall have 

hysiit nccasioD to employ the phrase. It must, bowcver, be anderstood 

Am tWv ia in tbe nerve, in an ordina^ way, no summation of nervoua 

eiim|)antble to the Himmation of muscular contractions. Putting 

(vrtain enseo which we cannot discuss here, we may say that the series 

rfifcuks *mit in at the far eiwi of the nerve start a scrieH of impulses ; these 

ttntl down the nerve and reach (he muscle as a series of distinct impuWa ; 

«4 iW tint change* iu (he niiifcle. (he molecular la(en(-period chan^, also 

Itm A acrirs ibe memlwre of which are distinct. It is not unul these 




molecular (.■liaii;:ea bec»rae irBnaforroed into visible changes of fiina that tmy 
flisioD or eiimiuultoi) tnkee place. 

$73. ruttiiiK [i)|:«ilier Lbe facts oontaiii^l in lIiU anrl tlie jin'CHltDg *ee- 
Umu, the fiillim ii];; luuy be taken as u brief n|]|>foximnl<: liWlonF- at what 
l»kc« place in a niuMte and oervc when itie Inner t* lubjected U> n fiiivle 
iiMliiction-aliuc'k. At the intitaiii tbtu tbe induwd current immki' inu> tne 
□ervG. cliKiigvn uociir. of wbo«e natiin; wc know nolliiiig corlam, oxa-ii* that 
they cnu»c n " current of action " or '■ negative variation " <jf the " natural " 
nerve current. Thwc clmngw profiHgiitc llKrinwlvra along iIh' ncrxT in hoth 
(Iirv<ctions as n ncrvnti» impulou in the form of a wave, haviug a wavv-len^b 
of about 18 mm., and a velocity (in frog'« nerve) of about 'la m. per MocmcL 
I'lUNng down the ucrve fibres to the niM«clc, flowing along lbe branching 
and narrowing tracts, iho wave at last breaks on the end-ptatcs of the fibree 
of tbe muscle. Here it is lriiusntut«d into what we may call a nmsde 
impnlae, with a shorter, Elcejwr wnve, and a greatly dimintfhed velocity 
(aooui 3 ni. pier secoDd). Thii) muscle impulse, of which we know hardiT 
tuone than that it is nmrked by a current of action, travela fraiu each ena- 
plate. in both itireciions, to the eiul of the tibre. where it appears to be Iom ; 
at all eveuta, we do not know wliat becomee of it. As this impulse wave, 
whose develupmeni lak<« plac« eulirely within the latent period, leaves the 
end-plate, it i-> fnlKiwed by an explosive deciim position «f material, )c«dtug 
to a iliHchar;^' "f carbonic acid, to tbe apgwaranoe of soom subcitaur« or 
iiul)«tJUic<3t with an acid reaction, and probably of other unknown thi 
with a ciin.-iideriihle development of heal. This ex]>loitive deoompoaitioii g[' 
rise to the vLtiblc contraction wave, which travebi behind the inviiiible m' 
de impube at about the tame rate, but with a vastly increatcd wave-length. 
Tti« fibre a» the wai.'e paaMs over it, awells and diorteoa, and ibiu brings its 
two nwit nMtn>r together. 

When repented shock; are given, wave followo wave of nervous impulse, 
ninscle impulse, and visible coniraclii>n : but the last do not knep dislinct ; 
they are fused into the coutinued shortening which we call tetanus, 

The Nature of the Chashbs Throitoh which as ELixTRir CV brext 
IB Able to Uexrbats a Nervoi» iHruL^K. 

.licfion of the CoixMatU OunviU. 

i 74. In the preceding account, the slimuhi» applied in order to give ii»e 
to a nervous inipiiUt! hib> always been siippi^'<l to he an induction-* hock, 
single or rcpeate<l. Thi* choice of slimuliu hns been made on accoiinl of 
the nimoft momentary duration of the induced cnrront. Had wc used a 
current lasting tor some considerable time, the problems before u« would 
have become more complex, in consequenoc of our having to distinguish 
between the eveiiis taking place while the current was passing through the 
nerve from those which occurred at the monient when the current WM 
thrown into the nerve or nt the motnent when it wns shut ofl' from the nerve. 
Ttiwe complications do arise when, instead of employing the induced current 
aa a stimulus, we use n eoiitlaul enrveni, I.e., wheu we paas thn>ugh the nerve 
(or muscle) a current direct from the Italtery without the intervention of 
any iuduelion-cQil. 

Ilefore making tlie actual experiment, we might, perhaps, naturally >un- 
]>o)e thiit the cou.-itant current wotild act an a Mimulus ihroughoul the wltole 
lime during which it wan applied ; that, ho lonv a* the current passed along 
Iho iwrve, nervous imnulitvti u»uli) be gcni-nili.-*r; and tJnU thwe would throw 
lh« musde into sometliing, at all event-'*, like telunu*. And, under certain 



I. thu >lix« Ink*- |iltw«; ocoukiuiillv il does liii|i]>ai) Oiiii at tlie 

b« ctimiil ia itimwti into (Im nerve IIm: iiiiux'li; uf the iiiui>cli'- nerve 

p*«|)*nui«i fall* iiiii) n teuinii*. which u c<jui»ii>mJ nmil the ctirn-iii is ihut 

vt; but •uch > nwilt U cxivpliiiimt. In l)i« vnsl luitjoritir of cn*es wh&t 

'"rr^"' ^ ** fvllovrs: At the mooieut ilmi ih<- drciiii h raadv. tko mo- 

n«U tbU tlio current if thnmn into iIh' urrvn, n tiaelij twiu'b. n >^m[i)e 

ooMnctina. tbi- k^-cxIImI auikiny fonlmeiion, io witniwciT; but uflcr tbU ling 

fw I sasr the muM-l« remaiiiA nltmlulrly iiiiiwcoDt, in ipile of iW current 

diotinuinc topsM ibr^iugh the ncne, ami lhi« fjuiSManctH miiinlnined until 

Um circuit t^ broken, until ibc current ie shut utT fnna the nert'e, wii«D 

■Dolhrr Hnipl« cituintctioD, tlie so-called tirmHny mntmrlion, n observed. 

TIm nrrv pHwaffe of a conatajit curnnl of unironn inlciuity ihn^n^h a nerve 

4o» DM, uodvr urdinarr eircumslancee. net as n Btinmlus (•eneraliuji; ii M«rv- 

utM ini|Mib*: Mick ttoimpukeitfODly set up when the current either falls iaio 

ur b •but olT frxiin the nerve, ft is tli« entrance or liie exit of the current, 

aad Ddt the continuKDce of tli« current, which is the Htimuliia. The •|uii»- 

MOW uf ib« nerve uid mu»cle during tlie pawaj^ of the curreut i», howercr, 

ifarwiiitm on the current. rtminininv unifunu in intenAily, or, at letui. not 

Inn^ MtddrolT increu«d or diminiiibMl. Any mflicieiitJy middeu and Inree 

iMMM or diniiautioD of itir inU-iiMij uf 'i)ie curreut will act like t£a 

OMfsof* or nit of a ctirront. and by j^ncratinK n nervous impuljte give rise 

H a cKMiinu-tion. If tW inlc4uil^ at the cnrrwit, however, be very tduwly 

■ad ^Tvdnnlly incmi»ed or dimioiiihi-d, a very wide rutgv of iuienoily may 

W (awvil ihniiigh willMdl any c»ntrac(ion lidog mcji. It » the xudden 

tlufD froa MM) oooditioD to aiiirther. aoil not Uie condition it(«lf. which 

laaai Uw nervous impnlM. 

Id manr ooMi, bolli a " making" ami n "breaking" contradion, each a 
uplc twiteh, ar« oWrvol, au'I Um ift, perbugu, the commoDeet event ; bnt 
*W ibe current ia very we«k, and again when the current U very strong, 
dibr tbe brmkinz »r the miikiuj^ iHniiraction may be absent; t. e,, there 
Mf b« a ouniraciion unly when lh« i-tirreut is thrown into the nerve, or 
•■rr afaan il i> «Uut »S fnmi the nerve. 

tnikr onlinarv cirounLiiauccii the omtriictixiis wituemetl wtlh tha eOD- 
Nai current rilfier at the make or nl the break, are of tbe natnro of a 
'4mfit " oontractioo : but. m lia« alreiuly be«-n naid, the ap|dic«lioti of the 
mmi BM/ giro rUc to a very pronouucnJ letanud. Huch a t«UinuB ia seen 
■WliBHa when tiM current >» tnw<h; Infttii^' during the application of llie 
wm, aometiaMi when tlw nirrvnt i* broken, laMing »onic time after tbe 
(Rent baa been wholly removnl fmni tbe nerves The former i» apokeoi of 
■ t " Making." th« lattt^ra* a "bronking" lelaniu. liitt ihote exceptional 
naki of the application of thf onnniant current nwtl »ol <tetaiii u« now. 

n* graal inicreal «tta>-hctl to the action i>t' the consl^uit current lies in 
At 6m that, during the pgifnijn* of the vurreiil. in «pile of the abwn<-e of 
ll avTOOB inipulc«>. ami llicr^Tore of all muscular c<inlraclionB. ihe nerve 
kfcrlba line both bclni.m and on each "idc of liie electrodes priifitundly 
mtiti la a owat peculiar manner. This mtHliticalioii, important bi>lb for 
A* %fc» h throws on the genenilion of n«n,-i>u» impuisM and for its pravli- 
•I aBpSortlona, ia kmiwu under the name of <Jr<tivt<inu*. 

\ilC fitarfrotontw.— The markeil rcalur« of tbe riectrotonic condition b 
llai tlta oerve, though apparently 'luiewent, is chanct-d in reaped to itA 
BrittUity: and tlui iu a dittereut way in the nrighborfaood of the two 
ihdnaW raspeetively. 

S»ffimm that on tlie iwrve of a muscle-uerve prepanilion are plai^ two 
1— [ailatiiatiliij ctecln>dea (Fig. 40, u, t), connected with a battery and 
>) with a key, to that a constant current can at pleasure be Uirown 


into or shut off from the nerve. TliiH M>ii«(aui c-urivnt. w)iii»e efleci> u-( 
■bout to stiiily. may be c»lle«l the " |i»lariiin}; ctirix^iit." L<?t n \n: the puct 
live ekctroilo or anode, aad k lite nejraiive doclriKie or knlbiMk-, both jiliiccd 
St H>nie dislaDCo from the ii)usi-le. iitid nlito yrhh n cerliiiii inU'-r«-Bl Ih-Mvcmi 
cftch other. At lh« jMJiit x lec lher>e be npplk-d n piiir of vWlr\>d<» 
Dectod witti iiD iiKluL'Uui) eoil. I^et the tiiiiw^lt' I'lirihnr hv coniicrtnl wi _ 
lever, M that ila i>iiiiimc(ionii tun In; ret-orckil iim) tboir mnouiit mra»iin-d. 
Before the |i»lnriziii|c current in ihroMii inln the i)or\-t^, let k niil'Ic in<bicti<>D- 
(iinck of kiionn iiitrimitr (n «mk nan bi-ing chomi, or, at k-Jifl, not one 
nbioh vroulil ciuim* id the iiiii»t'If ii Duixtniiini <><>ii tract toit) he tltruwn in ■! 
r. A votitriK-tioD nf « oerntiD nnwiint will fnllon-. That coiitmctiQU niar 

rio. ul 



Itnajtrtmxi. pjttt^axTiaia, -"ixli ibn arrrv ntxmA In A ivailMRwIteffiiiuIla Sioui 

Inmrh n Li Ihv BiiiVli.-. (' inv lnKlimlv of iliv miutaiil fiiirfiit: i repnWDtt llM (t«l dlien lk| 
liuliii'lliiii.*hijc^, uteJ 10 ini ihL- IntlHliilII} oT l)i« intrmaru anit Id. 

\k tnkcu as n luenaure of tb? irritJibility of th« iwrvc at th« pcunt f. Nov 
let itie |H)IuriEiug ctirr«nt be (hrown in iiikI lot the kathude or iieRmtive [Hilr 
1>C m-urt-Bt the luuw^le, as in Fig. -10, A. »> thiit the curr«at pawcB alntig tbr 
ncrVL* ii) a direction from the central nervows syRteui lowarxl the tnUKk; 
BlK'b a current is B{K>keu of a;* a ilr-rerti'liny one. The entrance of l)i« polai^ 
iiing current into the nerve will produce a " makinj; " cootravtion ; this m 
niD)' neglect. If while the current is possiDj; the «ain« uidueliiin-*bock nc 
b«rarc be sent tliroueh X, the contraction which rceulls will ht- found to Ix- 
greater tliau on tbe former occuiton. If the |i<>liiri/inK ciirroni hv aaw Mhnt 
offj B " hri-akiug " coutracliou « ill |>njliably he )>ri>diU'ed ; thiH wc lUwi may 
neglect. If, now, the jniiut jt. idler a short interval, he U|[iiin tested with the 
same imluctinn-Hhuck ait before, tlie coutraotion will be no lonmr greater, 
but of the same amonnt, nr ]ierhn|iit not >a great lu at tint. .During tbe of the polarising mrrent. therefore, the irritability of tbe nerve at 
tbe point r hi>» hcfn tvniporurily iHertnt^il, v\di* thi' >amc «hork applied to 
il caiiM* a grv-ater cnntnu-tioii during the prewJiiw; than :n the abMinoe of the 
current. But thi» i» only trnr iu> long il- the ])iiluri»ng current in a descend- 
tag one— so long lu thv jKiint x lir» on thi- hicIi- nf tho kathode. On tbe other 
hiuid, if the pijlarij:iiig runrnt had l>r<-n nn nKi-ntitiiiy one. with the anode or 
poaitive pole ncnrcj^l Ihc miisclc. a» in Fig. ^0, B. the irritiibilitv of tbe nerve 
at T wmild have been found \o\Kiii)iiii\i»hrd,xnt\nu\ of iiicrcasea, byibe ]>(]lar- 
izjug cun^iit ; tlie cunlraclion ohtaimxl during the paseage of the cuu»tMUl 



eamml «(niM bv Ine tlwn bi-fuiv the pntsage of the cumnl. or niieht be 

•IhM altDgaUwr, ani) the viminiclion iiftvr ihc rurronc Imic) been «Aut oiT 

■■■Id ba w grtmt, or jtt'rlia|» gix^nlcr. tlinn bcfoix-- Tlinl is to tuy, irheii a 

nMMtsai riirrent is iim'licH lonlicn-p. ibo irrilubilitr of llie iwtvo lietween 

thm piiUriiiit); vlcclrijilM mnA ibt? musrle is. during the passage of tbc curr«Dt, 

I kIh-ii the kalliocle i* nearest ibr niiiscle (and the polarmii); ouirenl 

llDU.i flud illiiiiiiishcil uli«D tlie auode is iienrcMt the muscle (and the 

{■lubitii; tnineiit nsccitilinK '- Ttie same result, mutiilu mulaiiditt. aud witlt 

HMB i|aBlifi('aLio(ifi wliich we iKeil uot disouas, would be gained if J' were 

fbccd, nut between ihe inuitole and the [lolariziiiK (.■urreiit, but i>u the far 

»im »f tbe latter. Hence, it way be ataied ^■^"^"^"T ''■i*' during the 

|aMBg« uf a cunnlani current (brouj^h a tier^'e tlie irrilnbility of tbc nerve ia 

vtenamd m lite regtnu nf the kaibotte. and <linruiijlied In tlie region of the 

uufAm. Tbe dtnngn in the nerve which give riie to this increujfe of irrita- 

hililT in tb« rci(ioii of tJie kathodes are «|>(>ken of a« hilelwlrult>tiu4, and ihe 

MfTc b Mid to bo In a kalelecimlonic i-nndiiion. HJiuilnrly tho change* in 

tl« rnfion of tb« anod? arc vjioken uf an <i>ii-/irfroto»tut, and the nerve i* nid 

to be in an aiflwiniloDic t-ondition. It ix alM oAen unial to «[tcak of tb« 

UivtectmiMiir incrawc, and luii-lertrotonic ilocrtMC of JrHmbility. 

Tkia Uw mMiw tnie nhnlcvtir Iw the ni<ide adopted for di.-icrmininK the 
ifriubPitir. The rt^till hol'U k"-"! not only with a xinglu induction -vlitick, 
bil tbo with n tctaniiiiig inli'rni[ii(.'4l current, with chrmicjil and mochani* 
olriiMli. li further Hpiware to bold good not only in a diisrclcd nerve- 
MkIs preparalioii l>ut also in the intact n«rve« of the livini: bo<)y. Tbe 
and (k-creiisp of irritabililr arc most niarkc<l in ihv inimwliale 

MUbdrbuod of the otc<;trodes, but spread for a considerable dii>tuncw in 
•aradiTfcUoa in the eiimpoinr ref,'ions. The same moililicalion is not con- 
laalbi tbeexlra|M>hir rcfinon, but exiata al»u in ihe in tnipolar region. In 
tW intrajNilar region (here luuAt be, of uourae, a neulrnl or indilfvrvnt jwint . 
tbot the katdectronic incn-ave niergcn into the an elect rot »nic decreaae, 
uJ wbtffi. therefore, tbe irriiabiliiy i^i unchangetl. When the )i»lariiing 
nnwiiiaifeak one, thin iudilfcr^nt jxiint u nt^nrer the anode than the 
krib«dt,bat U iIk nolari«iii)i! ciim-nt increuM* in inlonsity, dram nearer 
u4 Huvr tbe kathode im Fig. 41 J. 

fm. II. 

»■*■!« tLUnrmim TH> ViHUtnoB ur iHBttian/TT ui-uiNi Ri^tcnDMNOh wnn 
rouauisa rtunvim nr IvrttiaHO tnnsiTT, irroin fRogar) 
n*IKat> I* viiqnnd Id U* iJaoXl at .1. ilie k41b«d* al 8 : AB li luiuHiaDndT (hn InimiJOlit 
Matt. toM«kiirUnibr«*«>u-io«,Uioiianlana(ili«tiimb«to«'llwliM«Bn<t rvjifSHnwdlMln- 
■If, llut> tlbim. tnvraucil lirlutitlnr. n Wftiwim lh» (Okn ot • inak cumnl : lliB 
I tuaal r, U nmi IW nnule A. In |>i. ■ nroDCH I'umBl. Ihe liidlfltinil pc4ii( t. It iwanr 
I Ik iM dnnlnunan ••! LrrlWUIIiy la uwitoiniioiKit ■sJ ili* luprMw i<> knialccuuionut 
rUsn Imp,: IbeeflMI ■!» ipnail* Air a (ivtar dliUum Along Ibr «i(ra]vUir nt(ini» 
iHt AMH^ In rttb«<aB>n>iiuai«MeuK>beMUImoi« mulwl- 

TW ■OMKUil of IncrcMM and decrease iadepewient: (1) On tb6 >ti«Dglb 
tf tk» «nnu. iba Nronger current up to a cerlain limit producing the 



Knier eHbot, (2) On ihe irrilHbility of ibe nen-e. lUe more irritAhle, 
ttr condiiioDed nen'e beiog the more aHectetl by a current of the «une 

In the cx|>erim«nu jii»t de«crtbed the increase or decreuM of irritiibilitf 
t8 ukcn u> mean tbat the tame stiniuluH maru in ifae oDe ease a lar^r or 
more powerful, ami iu the olber case a smaller or le» ener^Uc impulse; 
bill we hav« remioii to tliink that iJie mere tirojiagation or conuuction uf im- 
pulsra slarlcd el«ewbcre la aldo alTected by Ine elevtrutouic CODdition. At nil 
evenU Knclf^'lrotonujt appeam to uffvr an ob*Uu-lc to the punge of m nvrvoiui 

§ 76. Eteeirotoiiie currenti. During tlie paatage of a conswnt current tbmuxb 
a nerrc, varlallon* In the electric currents belonging to the nerve iiMlf mav be 
obMTTed; and Uieno VBTiationH have ceriAin relation* U> tlip varinlions of tlie 
■rrilability of the nerre. Thus if a convtant current supplied by Ibe battetj 

Fw. e. 



Oijiotun iu.i«i>Aniin SUcmnognc CcannrTK 
/•ihv tnlorlilDS bAiierr.-wItblB liii<r. p ib« anoAp.auJ p' lh« kaihodr. At ih« Uft •Bdt«f < 
|dttp«of nciTc lUt uniiml curronc Oouv (lirounn Ihe jpiInrHimeler Q ttvtn g ioff\ ia tiiVdlracO 
oT iLu nrruHt; )i>aiirer(lou. ihenthiir. !■ (tio tmiisai Uinrof the inlvUlDR cormit: waM^ocntlr ft 
■IiiaanlamunJ, ulddlailHltiTlhiMlBii t . Th> ounviil at llio othor «.tiil <rf tbe |ilN* of ii«r*«^ 
IhHd A lo A'. ihroUBb Uie vilranoiagier M, floni In ■ coatnr)' dIrceUmi to itw poUrfdac cnnvnt ; R 
oonMi|U*QU) appBB Lu br illinliilttiiiil, u liKllCBtal by tboiltcii — . 

X.B.-Pradmiiltdtjr'iMkr. ttic |»lBrlidnr tumiit IdiarttUITaWl to be Ilirawii limttha nldill* 
at ■ FfNnor ncrrc, and tIWKiil»nuiaL>ivr r'*™*) >' t'lu iwovmlf. of coiin(lti*1llb»iiiiil«iMoo4 
Uiat ths Akiiuit nuy I« Ibfowii in anjiwhvia. atiil tbv litter onnnn-lci) wllb 1U15 two pAlnof (dnli 
wbMh nlll glT^ramata. 

P (Fig. 4a) be applied to a piece of nerve by means of two non-polnriuibie 
eleclrodc* p, //, tlie "current* of re«t" olitainable frura the rannuH pnims 
of the nm-e will be diflerent duriuK the paMaee of tbr pulariiJuit current 
friMn tbone which were uianifist before ur nK«r tlie current waa applied ; and, 
moreover, the obau£«a lu the uerve-curreote produced by tbc pofarisiug cur- 




will ihM b* lb« MUM in the nfijthborhDud of tbc ■node (;i) m tbonc in 
IW Mi^borboiid of Uw kath»<)« (p'y Tbtw let O aud H b« two gii]viui«< 
M»t< r » ao coBn«cUr<l niili tlio iwo piitta of th« nerv« aa to alTord i;ood aiid dmr 
•v14«BCa of tlir ''ciirrrnl* of r««l." Itvfnrci th*> pnlariKJi)^ current is llirovn 
iMo tk4 B«m. thr a<-r>11o nf // will onruny ii pmition inilicnlinfc ilic puiaj(« of a 
WtraatofK c«rt«in iiiitiisiir frocii A tu A' ihruugb the nlvsnoniPtcr (from the 
MUivvlaticlludiiinl Mrftice' to tbe ofigitiro cut «ud or the nerve), the circoic 
Wlaf e<MDpM*d by « currcoE ui lhen«rre ftvin h' to A, i. «.. tbe currvnl will How 
l> Um lUnctioa of tbe arrow. t^imiUrl^ thv n«odl« of will, b^ iix dcAactioR, 
Mkue tlw exlMcnce of ■ currenl fluwinx from ^ to jr* tbruugb tbc Kalvunome- 
ter, u»d tnm 9' toy ihruugb tli« nerve, io ibc directiixi of ib« arrow. 

At lbs iaitKDt that the poUrUln); current 1* tlirowii Into the norve at ;>;>'. tbe 

fwiWila at jm'. AA' will undtrgo a "oqfstive varintinn." that in. the nerre at 

MCh point will exhibit a "current of action" ci>rrRtpniidinf: I« thu ncrvoua im* 

|«1m. which, at the mnking of the polaririoK current. pOMUo in bath direclion* 

■hMK the oerTo. am) may csuM a oootraotioo in the atlached muscle. The our- 

nttt at action ii, as wo hare teen, of eitrrmcly short danUion. it Is over and 

|MW (a a mail fraction of u atcond. II. therefore, munt not be oonfounded with 

sMnnaaani effect which, in tli« cas« we iir« deuliii^' with. !■ observed iu both 

pItaBiMMUn. nia ell«ct. which 11 de|)t'iidi'rit mi the directi'jii of ihe |H>1arle- 

■(CWrml, MM follows; .Supposing tlial tbc polari/.ine current is Hnwing In tb« 

Antdn of the arrow in the nftnro. that i«, passn in the nerrc fmm the ixwilive 

J mi ode or anode p to the negative electrode or kathode //. it i> Tounil thut the 

nrtvnt tbroagh the g^VBtiooieier O ia iacnaBcd, while tluil through J7k dimin- 

xbid, Tbe (KiIariRlng current has caused tbe appearance in the oerTe outside 

ihs4Klfnd^ of a current, baring tbe wtme direction aj> itself, called the "elec> 

tntnir " current - nnd this e1«ctrotonic current mliU to, or Ukn nirsT frirm. the 

MMal oerre-cttrrenl or "current nf rent" sceording at il is flowing iii tbeaatne 

JbMieu sa that or in an opposite direction. 

1W iliwBitih of tbe electrotonic current is dependent on the >lr«iiKth of the 
pahiiiliit airreot. and on the length of tbc inirs)>olar region which is exposed 
L to the fUmtitiBK cnrrent. When a stmnit potariiintt current in used, tho eleetro- 
B Hlln fiwce of tbe electrotonic current may be uiucb |{re«tcr than thai of tbe 
■ aunl Mr«»-carrent. 

H Thi ttrencllt of the electrotonic currcnl vsHm with the Irritability, or vital 
H rwsftliM or th» n«rve, being greater with the more irritjtblc nerve , and a dead 
P Btm will not nuniresC electrotonic current*. Moreover, the propagation of tbc 
[^ uiJHsi b Mopped by a ligature, or by crushing the nerve. 

W* najT apMk or tbe conditions which girc rise to this electrotonic current as 
a f >>w H/ el«€tro«oniu nnalogoaa lo th*t pliyiolngieat elvetrotonus which is made 
bna by variations in irrilaoility. Tbc phyiical electrotonic current ia probably 
fo U> the aacaife of tbc (Hilariung ctirrcnt along the uerrc under the peculiar 
oadllleos of toe Hrinf; nerve; but we oinit not allempt to enter here tiitu ibb 
Wall subject nr ini'i tbe allied quoilion as to tbe riaci connection between the 

apical and tbe phyiinlogical clectrotonu*. though there can he tittle doubt that 
I latter la dependent on the former. 

(fl. Tbaae variations of irritahtticy at the kath'xlc ami anode reapec- 
Irwif, IfaiM brni)f;hi about by the action of tbe coitstAiii current, are inter- 
Ming ihenrelicnlly, boonase we may trace n connecliou between ihetu nur) 
tbi ncrvow iDipulae which la the reaiilt of the making or breaking nf n 
tmtrnA current. 

Par we have evideitce that a nervous impulfte is gencniled when a portion 
if tbe nerve puaea auddeiily from a norniul condition to n Mnle of Icatclvc- 
tMsoBS or fitm a atate nf notilec-iruionu^ hack to a uormal euiuliiion, but 
telka panajfc from a oorninl <<ondilion tn aiiele«lralcuus or from knti'lcc- 
inMKia back to a uomml condition Is unuble to gvnernlc an impg|»e. 
Hoe* wben a i^nslnnt ciirri'iit is "roado" the impuW is gi-uvrati-a! only itt 
lla kathode where th^ nerve [HMtifi ninldenly inUi kntelei'lmt'imi*; when 
ttamrmt on the other hand is " litoken " tbe iiuputsc in gcneratcil unlv at 
■iUiand* where iJie i»erve |MtsiN.>e suddenly luick from aneUictrotonus into 


» nomia] oandilion. Wo have au imlin^t proof uf iIim in ihu Factii lu 
which ff« <lrew atteutiou ii little while buck, rix., thnt a coiitrnctioD aoine- 
liincs oceuni at the " bre&king" only, MmHintcs nl the "nuikio^" only of 
the coD»lniit currvnt, tometimo nt hoth. Fur it in fotiml thnl thtg ijcponds 
partly on tho mrcngth of tho current in relation to ttir irritability nt' tbr 
iivrTc, pnrtly on the direction of tho current, whether iiM;cn<liDg or ^csceiid' 
ing; and tho results obtained with Aitron;^, medium and wonk descending 
and asronding cnrrcnls have been slnlod in tho Ibrm of a " law at' cotitroc- 
lioii." Wo need not enter into tho details of this "law" but will merely 
say that tlie results which it formulates are bc^t oxplaine'l by the hypocbe- 
eisjnsl elated. We may gidd that when the constant current is applied to 
certain structure)! comiKised of plain niuitculAr Kbrcs, whose rale of cnolrac- 
tion we have seen to fa« slow, the maklnf; contraction nmy be actually ae^ii 
to b^in ai the kathode and travel toward the aitode, and the break'toff oon- 
traction to bei^in at the anode and travel thence toward the kathode. 

Since in katelectrotoDuii the irritability ia increased, and in aneteolrolonua 
det-reaaed, both the entraiii-e from the normal cuiKlilion Into katelectroioDiu 
aod the return from auelcclrotonua to the normal condition arc iiulanci^ of 
ji uawajte from & lower Atage of irritability In a higher Htage of irritability. 
Hence, the pbenomena of electro ton iih wnuld lead us to the oonoepiiuii that 
a atimulutt in provoking a nervoun impulte pntduceH itn effect by, in »oinc 
way or other, suddenly raising the irritability to a higher pitch. But what 
wc are exactly to uiidemtand by raising the irritability, what molecular 
change i« Ibc («ti«e of the rise, and hnw either electric or other stimuli cnn 
produce lbi« cliangc, are mutters which we cannot discniu here. 

Bendw their tbuorvtic-al im[i.irtiiine, the phenomona of electrotoou^ hare 
nita B practical interest. When mi iis<-cttding current is piuwtl along a nerve 
goiiig to a mtticle or group of mus^le^, the region between the electrodes and 
tne muscle is tlirown into anelectrotonti^ and its irritability is dimintshetl. 
If the current be of aderiiialc strength, the irritability may bo »> much 
teteened that nervous impulses cannot be generated in thai [inrt of the n«rn 
or cannot paea along it. Hence, by this means the irrejjular contracliun* ot 
muscles known aa " cramp " may be abolbhed. Similarly, by brlngiuff into 
a condition of aneleotrotonus. a portion of a sensory nerve in whieh vinleni 
impulses are being generaletl, giving rise in the central nervous syaicni Ia 
scnaalions of pain, the impulses are toned down or wholly abolished, and the 
pain c«BM«. ^. on the other hand, we may at jtleasuru heighten lite irrita- 
bility of a part by throwing it into katelectnitouuii. In l£b way tho con- 
slant current, pni)ierly niiplied, becomes a powerful remedial innsua. 

We said just now that probably every ttimuIuH produces ita tdaol oq a 
nerve by doing wliat ibo conntnnt current docc when it a<Ms as a Stimulus^ 
vis., tuildrnly raising the irritability of the uvrro to a higher pitch. At any 
rate, the etimuluK «o ot^n employnd in experiinents — the induction-f bock- 
acts exactly in the mmc way as tho constant current. The induct ion -shock 
is a current of short duration, developed very suddenly but disuppeariDK 
more grnduitlly, and thii^ is true both of n making induction shuck, a shock 
due to the making of the primary current, and of a bmking shook, a abock 
due tn the breaking' of the primary current. The two dtHer in direction 
(beoce, if the makinj; shock be ascending, tbe breaking shuck will be deaccud* 
ing, awl viet ivnvj ), and in the &ot that lite breaking shock is more sudileiily 
developed, and hence more (loteot than the making shock; but otherwise 
tliey act in the name way. In each case, nnce the induce<l current is devel- 
uned rapidly but diMpjiears more slowly, there ia a sudden development ot 
electrotonus, of kalelectn>t()nus at the kathode, and of anelectrotoiiun at the 
aaoiie. and a more grmlual return to the normal condition. Now, ih«rc are 



muiy rttmrnm for thinking (hat in »)l ohm (he jnauii}; horn lli« normal uon- 
4idi>n 111 k»l«lwtroioniM ■( th« knlli<x(c is a nxjro potent siiiiiiiliis than tli^ 
ntani (rtmt antlectrotonna to tW uurmal cuuililloii ai ihi? iiiiudi.', and lliia 
•ill b» itill Biora M if lh« return to the uormal ritihlitiott lio much «loiror 
tiuui tha entiancs into el«ctruionus, as ia the caae in iin iii(tiictinn-#lu)cik. 
AimI ii wixtid appear that in an intluciioii -shuck, which, lu* wc hiivomid, 
clHapjNvn much more slowlj than it ii lievelnped, wc hiivu to 'teal nut with 
two atimuli— one at the shook |<ttAiinK into a nerve, and one at thc*hiick 
IfBvinit ibf nerve— but nith aiw uulc, thnt pruduoeil at the thwk passing 
tnUi tlie nerve, ilenee, irhen itn tnductiuii-sliock in mnt into a nerve, ono 
lus unlj is develo|>cd. and that at the kalhoJu only, the eslnblishmeBl 
lUB. This iR true whether tliu #hock be n making i>r a brewk- 
__ dinek — I. «., line to the inakiuK or brcnking of llio primarr current-- 
thnugfa, of course, owing to the change "f ilirvction in the induced ciirreal, 
•fast WBB the kathode ni the making shock booooiea llie aoodo at the break- 

l^rily, though Iff arc doling now with nerves going to ran«clee — that is 
\a Mjr, wilh motor iH-rvm only— vf« may nild that nhal ne linve said about 
tlectroluaua and the dvv<'lopBwnl of nervotis impulses by it appears to apply 
t^uallr wall to Pttaary nrn'ea. 
( n. In a general way niosciilar fibr^^f b*'have toward an electric etirrent 
r* aiurli nji do nervf fibrt^ ; but (here nre certain inijiorUmt dilfervnc*^ 
In Ibo lirM plnM-. niupcular fibres, dermd of nerve libra, are much more 
rradilj thrown into contractions by the breaking an<l making ol' a eouitanl 
niTTMit than by the more transient induction ■ehook ; the muACular Mib^tance 
iMia* to be more sluggish than the nervous sub6taiii.-e, and require! to be 
Mlad npoa for a hitger time. This fact may be made ime of, aim). ind«ed, 
ii b w dka l praelice made mm of, to del«rmine the comlitioii of the n«rve« 
•■i)iplyiDE a muMrle. I ( the intni-muAciilar nervo be Mlill in gcMKi condition, 
the noMle. to a whole, rojionil* nmdily tu single induct ion -shocks, beoause 
ikae tsa a4;l upon tbc inlra-muM-ular nerve*. If these nervtv, on the other 
ka»' I<wt their irritability, the muM'Ie diMv not r<«|iond readily in 

aa^- iua-«hucka, or to thv inta-rru ptt^l i-iirrcnl, but can still easily be 

ihiima ink' c«ntraeiii>nit by the ci>n<4AnL current. 

Id liie eeuind |»laoe, while in a nerve no iiupulsos, as a mie. generated 
Joriac tbr |M«age of a ountHnni mrrenl. between the brenk and the make, 
fntun] tliai it ia not ton drong, and ihtU it remains unilunu in strength, 
Ik HI urariznl nin>M:li.-. on the oilier hand, even with moderate and perfectly 
aaifiMin rumrni*. a kind of tetanus or iipp«rently a series of rbytnmically 
NfBlcd ctmtractioDs ts very freiiiieully wiinesKd during the padsage of the 
•anal. Tbe exact nature and cause of these phenomena in muscle, we 
■wt >!«, however, diecuss here. 

TnK Mtr^iCLe-NERVK PkBI-ARATIOX ah a ?tlA(')IING. 

tYI. The &ct* described in the foregoing tvelions ifhuw lUatn miit«le with 
ikaenrc may hv juKtIy reganled as a machine which, when oiimnlated. will 
^ 1 eertain unuMini of wurk. Hut (he actual amotint of work which a 
aowle-nrrvr [>rfparat>oo will do ts ftuiiid bo depend on a large number of 
■vaUMaDrca, and oi>nK»)Uently to vary within very wide limits. Then 
wiatinns will be largely determined by the condition of the muscle and 
Wn* bl rcapoct to their notriliou ; in other words, by the degrc« of irrita> 
tSqr ■lanUeMei) by the niitM.-le or by the nerve, or by lM>th. I3nt quite 
■fart tnta the general influences alfecting its nutrition nttd thus its irrilit- 



bililr, n muiclc'ncn'i^ prppnnilion t!> mflt-i'tt^I nn n-tfitrtlit llic ainnunt of \t» 
vrniU by a variety of othrr <'ireiitimtaD<<M, ivhi<'li vc ihmv bricHy CAiintlvr 
horc. rcsprviiig to it «iiPOc^cliiig mxIioii the oltiiiy nf vsrialixii!' iii irritnltilitv. 

Tlif injlufriw nf (lit nnlnrr unii madr nf njiplictlit>H of thf utimnlm. Wbrn 
WO Apply n wcnk etimului — u -kv^M in(fiiition->'hopk— to R nerv« wc gvt a 
smnll con Unction, n «[ight »)i'>ru-niii|i: of Ihc ttiiiM-lr; irhm ire npfilv A 
8in>nt!Pr etimrilii!— n Hlrongtur in<lucli<in*hiH'k — wp gel ■ lnrj»r t-imniiclloo. 
a fireutcr »IiorlPiiiii^ of tlio iniisdc. Wt- Inke. olh«r lliings Ining cmiu&I, the 
BiDdUDt of <.-oi)ti'aclion nf the muide iis a mmsuif of tbi' nerroiis imptilee. 
an<) my that in Ihe forni«r case n ivenk nr sli};hl, in the InlU-v cn^e n slmn^r 
or liirgiT. oervoui impiilBe \\\\% he«ii ;;i?neriiio(], Xou', the mu»cl« of the 
inu^cle-nerve itrepiirali'm coii^iiilti of niuoy nntscular tibree. niid thft aerVA of 
uatiy nerve 6brc«: and we may fairly Buppnife thai in two ex[«rinenta we 
may iu the one experiuieiit bring ihe iutiiii^tion-ahock or oiher eiimuliu to 
Iiear on a few flbrea outy, and in ibe other experiment on many or even all 
the fibres of thf nerve. Iu the former case, only those muscular fihreit in 
vbich the few nerve tIbreH*[imulaleil enil will be llirowu into contract ion. 
the others remuininj; <|uict, and the shortening of the muscle, aa a vltole, 
aince only n fen librMi lake pan in it. tvill neccnmnlr be 1cm than ythta all 
tlic RbrcH of the nrrve arc stimulad^l and all the fifireM of the mnacle con- 
tmcl. That w to Miy, thv amount of contractinn wtU d<-]icnd mi tbv number 
of librcf stimulated. For timplicily'* nake. however, we will in what fol- 
low*, exeepl when otlicrwicr indicatMl, mippn*' ibnt when a nerve \* otimu- 
lated. all the fibres ar« Htimulated and all the miundHr tihrri! ronlract. 

In »iieh a case the Mrongvr or larger nervous impulse leading to the 
crmler contraclion will mean the greater disliirliance in each of the nem 
hbree. What we exactly mean by th« grent«r disturbance we mu^t not dis- 
cura here ; we must be content with re^nrding the greater or more jKiwer^l 
or more intense nervous impulse as that in which, by some mode or other, 
mora energy in *ei free. 

So far i» we know at pmunil this ilillen-'nee in anintint or intensity. «f the 
eacrgy »rt Iree, is ihe ebief diflerence between \-ariiWs nervous imiMilsc*. 
NerroUM impulM-s mav diRer in the velocity which they travel, in tlte length 
and {NMsibly in the form i)f the impnlsi! wave, but the chief ilill'erence u in 
Strength, in, su to speak the height, of Ihe wave. And our prexonl knowl- 
edge wilt not permit n* to point out any other ilifTereneee. any diflercnc« in 
fundamental nature for instance, between nervous impulses generated by 
different slimuli, between lor example the nervous impulse generated by 
electric currents and those genernted by chemic-ttl or mechaoieni stimuli, or 
by lh<«e changes in the central ner^'ous system which (;ive rise to what may 
be called natural motor nervous impulses as distinj^imhed from tlioee pro- 
duced by nrtilicial stimulaliun of motor nerves.' 

This being preutiseti. we may any that, other things being equal, the ma^- 
nilude of a nervous impuUe, and so the luagtiitude of the enauing conlraclton. 
ix dirai'tly dependent on what we may tall the siren<;ih of the stimulus. 
ThiiH taking a single induction -shock as llie moat manageable stimulus, we 
find that if, before we begin, we place the secondary coil (^Fig. 14, >en. e.) a 
long nay olT the primary coil nr. r., no visible effect at all follows u|<on th« 
discliarge of the iuduelion-fiboek. Tlie pawage of the momentary weak cur' 
rent is either unable to produn- tiny nerroiis impulse at all. or the weak 
nervous impulse to nhich it giv«« rise is unable to atir the sluggish muscular 
Bubslanoe to a visible contraction. As we slide the secondary coil toward 
the primary, sending in an induction-shuck at each new position, we fiml 

I U will hr olwrrcil thai w«ara sivakltia nnw vxrliiiirslj-nC Ihp iirrvv (>f n KiUM'lij'nRte tman- 
tlAa.l.r, orvhii >ic*l>uil henmfli-ririm h inalni iierrv. WiudierKnwiylint'liliMiIIIIkrefficatiBlljr 
than nuilor iia|iii]t» u lU la fiiiiUrml laim »ii 




lfa»l at m reruin diflUoee between theEMmodarv itii<l pHniiry coils. tht> tiiui- 
Hr nmftendt In Htcli itiilufliou-shiMilc' wil'i a coutniction which ninkc^ ilMlf 
viijble in Ibe ■[i)[)i[«M |Kjet»ible rise uf ihe ik(iacl>i>d lever. TIiih pavilion of 
lbs onib, tlw hnlU'ry rrmuiiiinf;; tii« tame and oiliur thin^ IwiBjf e(|iinl, 
■Mrfc* Ihe wini'miiV niiuulus jfiviiiK riae W the ruiuinial iM:intraclJi>n. Aa the 
■Mooilarr mil i.-< Im'UKlii nearer to the prinuirv, (he ci^ntracltoiM increiwe in 
Iwigbt cnfTiM|»tiJiii>: ti> ibe UiervHM iu the iHU-nnily of the«tiniiilu!i. Wry 
aoaa hammtr na incmiiH; in the MimuluN Cftiued by furihrr cliilinK >1k- 
MCMwianr coil ovr>r the primnry failK to enuM anr iricrvuw in thv oritrniv 
lioii. Tbi* iiidii'at'i that tbv Majrtm'i/Mimiitnit ^viiiji Hoc to ihu niaitimnl 
«aati»cliun htu If4'«ii rvuchw) ; thougb the shoclut incmiw in inCvtmily a« 
the wcoadary ooil i* pudNd furtber and riirthi-r over Ibe primary, the con- 
tnrtlona mnain »t' the nine height, until fuiiguo lower* them. 

With «ingle indiK-tian-sliocks llien tht- miiKruliir contraotion. aD<l by 
iaftrmce tlw nervvtu iiapulM. incn;af>v» with an incroiiw in tbe intensity of 
the ititDultW, bMireon the limit* of the minimal and iniisinial uimuli ; and 
lUf dMMSwkKUie »f the nervous impulse, and so of ihe contractioo. on the 
MTCogtA of tbe stimultis may l>c oWrve^i not only in eleetrio but in all 
UiMb of Mimall 

It mavhera b« remarked that in order for n stimuluH to beetl^tire, a 
<*TUin atm[ADeBS in its cetion is oeoeaaarT. Thus aa ire have »een the con- 
>L>nl ctinvnt when il b fMAinj; throcigh a nerve with uniform inleiiitity does 
Mt pvi; riae to a nen-oua imputac. and indeed it may lie incmiiKil or 
<fiMini»he<l to aluwet any extent without ftenerulin^' nenvma impiiUta. pro- 
vUmI ifaai tbe ehange be made (•radually eiioujch ; il t^ only when tlterc 'i» 
■ addon «bMi|{e that the current beonmen eHi.>4:live ns a miraului'. .\iid llie 
ntmto why tbe breakiii): induciion-sliuck in murL- piient iu> a miniidu* than 
the malcing «back is bcxaitu>! an we luive sorn i M-t > (he current whii-h ia 
iMlncwl in thr MVondary coil of an imlurtion- machine at the breaking of the 
(mmary circuit, is mon rapitlly (level<>)xi(l, and has n sharper rise than the 
tarrrnt which ap|>rAre nhi^i tbe priniary circuit in made. Similarly a sharp 
lafi r>n a nvrre irill pmdu<?c a contraction, when a gradually increouiig 

Iiiwaurv will fnil to do so : ami in evnenti the efficiency of a atimulua of any 
,iad will depend in pan on the MiJdcDnesa or nbrupln«ee of its action. 

A •tiinuliis in ortlcr that it may be effective, muat havo an action of a 
ivrtaiu itiimlion. the time ncceeeary to produce an effect varying according 
In tbe strength of the •tiiiiulus and beiuf; ditlWreni. in the case of a nerve 
IVnm wbnt it ia in thecMeof a muscle, [t would appear that an eUtrlnccur- 
not applied to a nerve muat have a duration of at Wet about O.UOIS *etv>ii<l 
In oiuap any nintraciion at all. and needi a longer time than iht* to produce 
ill Atll effect. A muac-lelibre a|>aTi from its nerve fibre re>)uires a &u]l 
kdgcr duration of the ttiiniulua. and henee, u we have alreiidy rotated, a 
■iMde puiMUt^l by iirari. ornhieb kaa otltcrwiM loM the acliiin of iu uerves, 
■ill n«i rupcxid an readily to inductiou-sfaocka as to the more slowly acting, 
hlMtkiog and making of a conuant current. 

Ib Um om of clirclric uimuli. tbe Bamc current irill prwluoe a stron|^ 
nMraetiMi wh<m it ia *ent along t)ie nerve than irbuii it ii aent aerom tbe 
wnre: indeed il ia mainminiMl that n current which {Mate* tbrougli a uerve 
b n ahtolufly tnuufvenc directiun in ]>on'CrlM» Ui generate impuuea^ 

It would aU(> nppMr, at all evcutN up to certain liniltji, that the longer tlie 
(inr of nerve through which the currviit poase*, tbe greater is the eifect of 

._ Mihtv ikt WmUiit w nuKUiaikoekBreMkeBied. DM iMSFtlmw c— aal 

«• oikrr. a*. M !*• luin <MU>d, Ibv Irni U«d* uf ikMk dUftn Iu dlDcttocT. Ik* bnaklaf 
(to BM* fDiani 



When twu pain u( electroden itre pincod on the nerv« of n long uirl per* 
fealy l're»h mid Hucoeuful Derve-pr«]»t ration, one near to the cut end, and 
the other nearer the muscle, it in round thnl the Htmc vtimuiiis producee a 
gre»(cr contrnclion irhen iipplied through the former pair uf electrodes ihtia 
ihiMu^h the latter. This has been interpreted as meaning tliat the impulse 
Staiteit at the further eleclrodee |^the» islrengih, like an a\'nlaiiehe, in ila 
progreaii to the mu«cle. It is mom probable, however. Chat the larger con* 
traction produced by Himiilatioii of the pari of the nerve near the cut end 
is due to the stimulus !<ettiiiK^f<^'! a larger impulse, i. e.. to tliii part of tha 
npTve beinj; luun? irritabk-. The men seotion, possibly hy deTelopttiK ii«rvu 
currents, luirreaitai fur a lime the irritability at the cut end. A .similar 
l^reaier irritability mav honever nl«o tie observed in tho ptirt of the uem 
nearer the ipinul mrd while ii ix mill in oonucctioii with the spinal cord ; 
ami it ia pus^ibli: ihut the irritnbilily of a nerve nuiy vary oon«i<lerably at 
dilfereDt puiniit of it^i c'iun>c. 

$ 60. We have luvii that when oin^Ic xtimuli aru ntpcated with Kullicient 
frei)iiency, the individual coiitrnction* arc fuied tnli> tetanus; nc the fre* 
queiicyuf the ropotition is incrc4UH^, thu individual oonlraolions are leas 
obvious tin the curve, until at last wo got a curve on whifh they iwcm to be 
entirely lotft and which ne may qwak of n» a complete tetanus. Br such a 
tetauuit a much ^Evter contrnclion. a much ^rvalcr shortening of tl>e muscle 
U of course obtained than by sin^ilc contractions. 

Tbo exact IreijUcncy of repetition rcijuired to produce complclc tetanus 
will depend chiedy on the length of the individual contractione. and ihia 
Taries in different aniuiaia. in dilferent niuiclcs of the same animal, and in 
the tame muscle under ditferent condilions. In a cold'blooded animal a 
dngle contraction is as a rule mure prolon^^d than in a narm-blooded ani- 
mal, and tetanus is caiise<iiifntly piuduced in the former by a lea* ft«>|uent 
repeUtion of die utimuluti. A lirml muscle has a longer contraciton than a 
freah muscle, and hence in many Ivljuius curves the individual ontrnctiona. 
eauiy reci))(ni/i,il at lirst. dieiip{H'itr later un, owing tn the individual contrac- 
tions belli)! It-n^thcned out by the exhaustion ciiii»cd by the telanu* itaelf 
In many niiiiunT», p. 7., the rabbit, somi^ musi-lis? i.siich as the adductor mae- 
nus fciiiorin^ arc paio, while other* (such n.i the «emiicn<lino«iis) are rea. 
TIte Kid muitclnt arc not only mora richlysupnlied with bloodvcwcls, but the 
muscle suli»innc« of the fibres ooutains more nwraoglobin than the pale, and 
there arc other etnicturnl dilI«rcneeB. Now tho single contraction of one of 
thaw re<) muj>clcs is more prolonged than a single contraclion of one of the 
{Mite muM-les produc-ed by the same stimulus. Hence the red muscles are 
ibiuwn into complete tetanus with a repetition of much less frequency than 
that rcijuircd for the pnle nmaeles. Tlius, ten stininli in a second are qnit« 
sufBdcnt to throw the red muscles of the rabbit into complete tetanus, 
while the pale inusclot reuuire at least twenty stimuli in a second. 

Ho long sa signs of the individual contrai-'tions are visible on the onrra of 
teuuius it is easy to recoguiiii! that each Htiiuiilation priidueix one of tli« cou* 
Miluenl single contrmrlionH, and Unit the number su to .4{iLmk of thtt vibra- 
tiofis of the muscle making up tht- tetanus correniiouiU to the number of 
stimulations; Imt the <^u(»tinn whether, when we increiuH' the number of 
stiiuulatiuns l>eyond that iiccmiary to produce a complete letanuK, we still 
increase the nnniWr of rtm^titm-ni single contractions w one not so easy to 
answer. And connected with this r|U4«tion is another diHicult one. What is 
the rule of regietition of single contraciiims making up thow tetanic contrac- 
tions which us wo have »aid are ihi; kind of contntctions by which thevolnn- 
tan-, find indeed otlicr natiirnt, movement* of the body are carrieil out? 
WW is the evidence that lIick- are really tetanic in character? 




WbsD a mwde is lUrowu into teuiiuii, « wore ur lew iniuioM] Mnnd li 
prixlucnl. Thb may be heard by upnlyiD)r a M«Uwwopc dirwtly ovtr a 
floBirwrttu^ lauaele, and a dmilar aouoa but uf a more mixixl origin and ka* 
iraMwoctky may be heard when tlte maixeicr iiiUNcle* are furvibly conUmcud 
or «beB ■ finger ii placml iu tl»e «ar, ami iliu muscla of ibe Mine ann an 

Wbfa the M«ihoaoofi« b plan<l over a Riu*clv,tbvnorvoof whicli iHvlimu- 
Istad by Miicii<<ii»liod(a repeated with viirviiii> rrxviui-ncy. llii< itotc heard 
vQI vary wiib tlii- iroqucncy or (he ihiM'k*. Wing of hie\ivr pitch wtlh Ura 
moro rr^«lu*^ut ■hwlc*. Now ic ha* bwn thought ihal Uii- Tihntti'Mtc of tho 
muack giviii); riw to Uw " inutoU- Miund" arv tdniticaJ with ihv liitgk- con> 
uractioDN making uit the tvtttniui of tho n>u»cK Aod eiiit.-o, iu the luimnn 
body, when a luuacle i> thrown into (.-onlnictioQ in n voluntary cITori, or 
incHad in any of tb« ordinary natunil movi.-menle of the body, (ho funds- 
meatal tone of tb« sound oorrmponds U> about Hi or 20 vibrations a Becood. 
it ha* bera eoocludnl that the contraction takinc place in eucb cnsee ■• a 
'T^f Ttr cf which the inilividuat coolniclionH fottow each other about 19 
or 20 llaWi a c«4.'ond. Itui invntij^nliona st-eni to show that the vibrnlionB 
giviag rne to the muscle sound do not renlly correepood to the 9hon«iun|p 
aad nlaxaiioiu of the individual contractions, and that the pilch of the note 
maooL tber e face bs taken as so indictiiioii of the number uf ^iugle vontrao* 
ligae BUtking op the tetanus ; iiidee^l, ait w« nlmll ba iu iij)eaking of the 
MMiMfa of tlie heart, a single muMular contruciiou may produce a sound 
■Uch tboggh dilleriotf fruui ih« »ound given out during tvtatiu* has to a 
BNlain axtent mueicaf olioracterB. Neverth6l«n the ;i|>ecinl cbarHctcr* of 
Ihk noMle Muod ^ven out by muwlee in the nniural movcmi^ni* uf the 
body may be taken es showing at leut that the contniotiomt of the mii*clc 
a Umm Biovementa arc Ictaiiic in nalnra, and tho stmilnriLy of the note in 
■U Uw voltintary eflbrta of tho body and itidwd in all niovements carried 
out by the central nervons system is ai \ftut consonant with the view that 
tW rvptrtitioo of sinck contractions is of about tlio Mme fret|uency iu all 
(bar niiiTenienis. \\ hat that frec)uency is, and nhclher it t<> cxaetiy ideiiti- 
ral in all tbeM movements, b not at pnsent perhaps absolutely determined : 
b(t OBTtam mrkinjp on the my<)>craphic tracing of thew uoveweutti and 
olltar Iwu eeem to mdicaie that ii is about I J a second. 

I BL 7%e itijiuenee o/ Ike tond. It might be iniagioed lhal a muscle which, 
«bcfi loaded with a given weight and stimulated bv a current of a given 
iairtuity, had coniracietl to a certain extent, woul<f only contract M half 
lluU rxt«ut wbeii loaded ailh twice the weight and stimulated with the huoh! 
ttfliahia. Such, howi-ver. is not neoesurity ilie case ; the lieight to which 
tW weight b ni6vt\ may lie in thv second Inatanoe as great, or even greater, 
ikan in thv fint. That b to say. the neeistance ofTcfeil t<> ilio coniractioD 
sttuallr auiimentd tlte ooatiaction ; the tensiou of thi- muscular fibre iucreosea 
ite Csnlity wttli which tho csploMvc chaiigex nstulting in a oontrnctiou take 
fhra. And wc have other evidence that anything which ti-nds to stretch 
the muacnhir fibres ; that luiv tennioti of the mu*cutnr ttbrvH, whether during 
Mt or during contraction. increaM« the motalMlism of the muMlc. There 
Kof cvtirv, a limit tii thi* favorable action of the resistance. Aj the load 
cNitimits to be incrtaM'd, tho height of the contraction is diminbhu'l, aiul at 
Isai a point b reached at whicli the muscle ii> unable 'oven when the stimulus 
ibosra b ihasiroogeMt poaiibU<) to lift the loiwl at all. 

la a musclSTMwed as a machine wr have to dcjil. mH merely with the 
W^bl of the contraction— that if, with tho amount of xhortcniitg — but with 
'•wnrit dtmek Aod this is measure*) by multiply inj; the tiiimber of units 

LM^t to which tlw load a raised into the nuiiiber of nnitu of weight of 





















tbe load. Hence, it ia obvious fVom th« foregoing observatioaa that the wor 
done moat be Inr^ly tlepciKleiii on tlie weight itwtf Thus, there b n certuin 
wcijfht ijf lotid with whi<:!i, in any given luuule Btirauliit^l hv a i^veu 
BtiiniiliiH, the incut work will lie done, aa may foo Men iVom ih« follnwiDg 
examfile : 

Ijnil. Ill eni.iiiiii«* 

Haiubi or oonmcatm. In inlUIuiMna . 
WwliU'JiM, III grmni'inllUniuLrai .... 

i 8S. The ttijlumi^ 0/ Iht mxe and form of the mvtele. Since all liuown 
mutciiliir liliTTfl arc much ehorier than the wavo-l?ngth of a contraction, it 
is ohviouH ihsc (he lon^'«r the tilin? ihe grenter wit! bo ihe sborlening ciiu»ed 
by the mine contnictiori wiive ; the i>realer will be the heighl of (he con- 
Iraetion with the mtnv itiiitiiiluH. Hence, in n niuecle of pariillel tibree, the 
hd^bt to which tlie louil in rained nii the result of a giren fttimulus applied 
to Its nerve, will dejiend mi the tenj,'lh of ihe fil)r«e, while the nMisinium 
weiirht of load <:ii|)ttbli< nf lining lilted will ilepend on (he number of the 
fibres, ^imt the loud i.-< dintriliulcil among them, uf two uiusclee, tliereCore, 
of equal length (iind of the mme nunlity) the ranet work will be dune by 
that whirh hnn (bn lnrg<-r numlM^r ol librai ; that ia (o aar, the 6bree. being 
of e>|iial width, which ha* thr ^reiitiT Hcctional area, iiud of two musclea 
with eijtial MOlionnl arcu.". the niont work will he d<ioe by that which ia the 
loufj^r. If the two muKch-K iirc unrcjiml both in length mid actional nrea, 
the work done will hu th«; grcntor in the one wbith hiia the larger bulk, 
whii'h contain" (he grvntcr niimher of cubic unilit. In xpi-aking. ihcrrfnre^ 
of the work which cnn Iw done by a muscle, we mny uki- il-> n Miindaril a 
cubic unit of bulk : or, the dpccilic grnvity of the mu.idc being the Mimo, n 
nnit of weight 

Wo lourn, then, from (he foregoing paragraphs that the work done by a 
niui'cte' nerve prepanilion will dei^end, not only on the nctivity nf the nern 
and muscle as detenuined by iheir own irritability, but tiho ou the chnmcler 
and mode of applteutlou of the Rlirnulus: on the kind of con traction (whether 
8 single eiia^ni, or a sKiivly re)>eated or a rapitlly repe&led tetanna) o« (he 
load itself; and 'ui the »mi and form of (he muscle. Taking (he iiioel Ihror- 
able circuniNlanci-ti, vix., a well-nourikhed, lively preparation — a maximum 
uiniuliiM caiuinga rnpid tetunux and an appropria(e load — we may deter 
mint? the maxininni work done by a given weight of muscle. «ay one granirne. 
Thift in thii i:nM! nf ihc niuHcU-i* of the frog has been estimated at about four 
grani-nietre» fur one gramme of niuide. 


*i 83. A muscle- nerve pret>aration at the time that it is rcmored from the 
body [KMUMaci a certain ilet;r^<e of irritability ; it rc^^ponds by a contrat-tiou 
of a ct^rtain iiniouDt (o ■ atiniuluH of a certain slren^'lh applied to (he nerve 
or to the muscle. After u nhilc^ the exact period, depeu<Iiag on a variety 
(if cireumstaiiccD, (he xnine Ktimuluo pmdueei^ a smaller contniction ; ■'.«., the 
irri(abili(y ol the prepanitiuu ha:> iliminlKlied. In other words, ibe muade 
or nerve or both have become jiurtiiillv " exhausted," and the exliaustion 
Buhwinently incrrn«ca, tbu luuiie stimuliin pnidiiciug smaller oun tract ious, 
until lit last all irrlUibility i* l<»t, no ^timiilnn, however Ktroug, pniducing 
any contraction, wlicihcr appliitl to the iKiri'e or din^itly to the muH-le ; tuid 
eventually the muFcIc, tus wc have mi:.a, become* rigid. The pnign^to of lhi» 
exhaustion it more rapid in the nerves than in the niusclca; for some time 




•the DtTW-tnink Km ctattd to raepoiid to even the «troD)i[fist slirnuluB. 
tractioDi niftv Iw obuincd hj apptrinf; iho stimulue directly to tlie diiib- 
«)& It ia much more rapid iti ihu wsnii-hlnuiled lliiin in lh« o<ild-l>liii>i]c<) 
■ni— bi TIm muscica and nervi^a of tbu former low thi^ir irritability when 
naDBTod from the body, tSter a period varyiog MCcorditiL' to droumntaiiocK, 
ftwB a few iDiDuta to two or three boun; thoae of cold- blooded luiiniiilii 
(or « Icut of an amphibian or a reptile) mav. onder f«vonblc conditiutiH, 
ivautia irritable for two, three, or even more ilaya. Tbi; duralitui of irrita- 
bilU; in warni-blaoded animaU m»r. however, be coiividerably pn>UMigod 
bjr ivduciug the temperature of the Dody before death- 

If with aocne thin \>odj a Bharfi blow be ttniclc acruM a miucle which linn 
•(Htf«d lato the later *i(agw of (•shaumioa n wheal laalin^ Tor ai-veral *ecr>ii<U U 
4«««loptd. Thu wheal appcani la bt- a cODtraction wave liinilcd iti tbi' pnrt 
atrttck, aad diaappearing very «towly without extending to Ihc nciubbnriu^ luua- 
•alar Mihetaitce. It haa been called an "ii/ta-inunfyar'' mutraclmn, because it 
■af ha bmaghl out evea when ordinary Mtimoli liaTeceaaed to produce any elTcrt. 
Il ■•¥. bowever. be accenpanted at it* bffpnning by an ordinary coutraction. It 
b nMWr produce<l in the livinic body on the pectoral and other mtuclea of per- 
ana anlMing from phthlab and other exliaujitirig diaeaaes. 

Tht# natural exhauniou and diniinutioo of {rrilnbility in mii»c)e# and 
■errea removed from the body may be modilied Imib in the rum of the aiue- 
de and of the nerve by a variety of drcumnljinoe*. Similarly, while the 
arrre aod muacle Mill remaio lu the body, the irritability of the one or of 
th» olbcr may be inodified eiilier in tlie way of inerca^c or of decrcR^e by 
eanain general influeucea, of which the niuat important are acveratice from 
iheccDirmI nervous ayMem and variatiooa in tem|>enilun), in blood-mpply 
tttd in functional activity. 

n* rffft<» of tefmnct from the etntrai nerwuu tfftietn. When a nerve, 
fudi, tor inauuifle, •• iJm aciatic, is divided in tUu. in the livins body, there 
», flist of all. olMwrvod a alight incrcAH- of irritebiliiy, noticeable eapcciftlly 
tmx llw eat end. but after a whilo the irritubiliiy dimtnbhee and gmdually 
fcyHiWra. Uuth the slight initinl incrcaw and the Bub«(]uent dccreate 
bpa •! the col ntd and advance cctitrifupnily toward the |Kiriphcral ter- 
■ftalinmi This ccniriln^al fcuUire of the Iom of irrilidnlity ih ofti'ii spoken 
<f M tbe Ritlcr-Valli law. In a mammal it may he tu<t or l\\TW ilavx : in 
tfrog, aa maJiT.orevcu more week^. boliire irriiabilltr hiu duiapiicurcil friiro 
the Derre-trunlt. It is mainlaine^I in tlie >imali laiid utpv-^cially in tbe intra- 
nntcalar) braodHa fin* Mill loiifjer periixie. 

Thb oentrifb^ Iocs of irritubility ia the forerunner in the i>eriphera] 
wrtioo of ibe divided nerve of airuetural chanif^ nbich proceed in a sini- 
W centril'uptl manner. The medulla Miflera ^uu))cea iumilar to thoae seen 
fa Dcm llbrea aA«r removal from tbe body; Its double contour and its 
ehanuitariatic indentations booDme mure marked; it breaks uti into small, 
imgvlar fracmenta or drops. Mingled witJi the fat particles of the m4Nlulla 
at aaan amaJl DUUi» of pnitcid material, which appear tii Ih- derived from 
iha proloplaam around tlw nuclei. Meanwhile the axis-cylinder also brealti 

Sinto IVai^nMtita, and the nuclei <>r the DMirili-mmu divide and multiply, 
r bitty (-KUiitituenla wbaoquently dc^-reoM- in amount, tbe prolcid material 
iacnaaiog or not dinnnishtne. aihI thus the contents of tbe neurilemma 
htavan each two uodm is reduced to a mass of protrid malcrial, in which 
tte f^agmeota of tbe aiisHjjliiider can no longer be reooniiaed. This man, 
tbich sUl) rMaina sonia tat globules, is studd^ with nudei. If no regcner* 
itioa tak<« place theeo nuclei, with ihfir proteid hc^l. eventually dinpjtear. 
Id the cctttrul porttoo of the divided ucrvir similar cbangen may be tracetl 



M tttV only M tbe next node of Ranvier. Beyond thk the oerre unielly 
remiiili* in H nunnul con il it ion. 

RweueriiLiun, n'hi-ji it iircuni, iit njipiirvutlr cnrriM] ant hy lliv pcrijihvrnl 
pvtwin of till! uxis-iyliuilrni of llii! iutjit't o<»itrul porlion. WIk'II tliv cul 
endu of the aurw an* clmw top-thcr the iisiK-oylimlont grawingout froiD the 
c^nlrnl [wrtion niii into uuA lii-twci'ii tliv *hnink(^ ncurilMQmBa of the 
IwHphrnil |H>rlinii ; hut iniicli iin<'i>rliiiiily »tiU cxii>l» u to the enact nnrt« 
wliicli the prolirrrnlcd n^^iiclfi iiml llic proleiil mntvrinl rcftirred to abore, 
fltid tliv iiUI nxi^'L-ylinilcrB of the pcnphornl p.irlioii respeoiively play io 
jfiviiic rieo tu the new stniclurc* of the rep'nprnlod tiltro. 

Saon a degCiieTatiun mnr bo uWrved to ^xteiid down to the very endings 
of the tierve ici l)ie mii§cle, iDeluding the end-plnte», but does uot at firsi 
atfect the inuBL-iiltir eiib«tnDee il<«lf. The iiiiiscfe, ihouith it bad h«l all its 
tien'oiiaelenieiiU, still reiiiaiDH irritahlo towani stimuli applied directly to 
itMlf: an additional pruof of the existance of an independent inux-'uLar 

For aonie tiin« th« irrilnhility or tho mtuclo. n w«U toward utimuli applied 
directly Ut ilnelf nc toward iboM- upplivtl ibrousb tbc iinpaiird ncrvu. •ceni* to bo 
ditniiiiabed : but after u u'liile a pvL-uliHr i-i>iiiliiloa (to wliidi we bnve already 
alluded, { 78)_ oeta in, in wliich Ihe muscle 1h found to bo oot eaally Bliinulaie<) by 
single induction -shocks but to rtvpond ritndily to tlie innke or break of a eon»lant 
current, [n Tact, it ia said lo bc<u)mv nvcn nxirc lenntive to tlio Utt«r mode of 
utimulation than it vru when lis nerve vtHa iuUi<.-t luid KiDCtJonally acUve. .4t the 
mme time it also beconiM more irritable toward direct mechanical dtiniuli. and 
Tery frequently fibrillar contmciiunH. more or Iom rhythmic and apparenily of 
Bpnntaneous origin, (hougli thc^ir cHUsntion is ohscure, moko their ap|>earanc«i 
TliiR plinkc of hci);bleiie(l seiisilivcnvaa of u musde.MpEicially to the constant 
current, nppenra to reach ii^ maximum lu man ui about tbe seveutb week alter 
nervoun impulses have tensed, owing to [lyury lo tbe aervea or nerToiu centre to 
mich the muscle. 

If the tnusciv thus dcprivoil of ila nervous elements bo left to il«elf iia 
irritability, however teetMl, woner or later diminishes; but if (be muscle be 
iwri'idieally thrown into contractions by tirtilieinl stimulation nilh the oou- 
Miuit current, the decline of irrilnhility and atlendnnl loss of nutritive power 
inav be poel{>oned for some conniderable time. But as far as onr esperieuce 
goce at present the arlitieial atinuilalion cannot fully replace the natural dae, 
and 9u»uer or later Itie muscle like the nerve suHere degeneration, loeet^ all 
irritability and uUimulely its place is taken by connective tissue. 

§ 84. Tiir iiijiuenK of (r-mpenilurc. We have already seen ibai sudden 
heat (and llie same might he said of cold when sufhciently intense), applied 
1(1 a limti«<l )iartof a nerve or muscle, as when the nerve or muscle is touched 
with H hut wire, will act as a stimulus. It is, however, much more difficult 
to generate nerv<iuK or muscular impnUea l>y cxjKNting a whule nerve or 
tDUscle tn a gradual rise <>{ lem[Jiirtiture. Thus, according to mott obflerras, 
R nerve bolonifiug to a niimcle' may be either cooled to 0* ('. or below, or 
heated to W C. or ercn 100° C, without discharging any n«rvoui> impulses, 
u shown hy the nbeeucc of contraction iu the attaclicil tnuscle. The con- 
tractions, niorvorer, may be alMint even wlicn the heating ba:< uot been very 

A muscle may be gradually cooled to 0° C. or below without any contrac- 
tion bein;; caused ; but when it » heated lo a limit, which in tne case of 
fr()|;'s musules is about 4.^^ C.. of mammalian muscles about 50" C, a sud- 
den change lakes place : the muscle fulls at the limiting temperature into a 
rigor mortis, which is initiated by a forcible contraction or at least sliortvning. 

< T1iaBeUon<irnldui<llie*laiiM(uary utnvirLlltr«<ouiiid(n«(liaRl«Hrp(intotio(ilioir«fk. 



M-xl<raic w«nntli, e. y., id the fro^- an lucmu of t«ni|Ji-m[i)ti.- u[i (u 
•oOM'wbBt below -lo^ C, ftvufs bolli niuscular and nervniu irritnbiliiy. All 
|(m molFCiiIar jtmcoees are ti«st«ne<l nitil fiidliuitnl : lli« oonirni-Uun it far 
* ipveo ctimulut greater aiit) nvore rapid, >. r.. of i>hon<T (|uni(i»n, mm) iirr- 
X"m impillw* are geiiented morv rauiily by »ltglil »tiriiuli. Owing to tlic 
<|aklcrmitf; of the cbcmical vhango*. ibc viipiilj- of new niiucriiil may prnve 
iiaoutlinrnt : benee muacl«4 and ttcrvM rcmovct from tliL* budy Wme thi'ir 
irrilBtnlitr mun' ni|>idly iil n hi^h limn at a low t<'iii|H'rnlure. 

Thr );r>(lual njijilicntuin of 4'uld tn a lu-rvi', f»|ic(-iiiUr wbcii tW tcnipera- 
tarv i* ihiH bmuglii near t<i 0° C., >tnckcii« all lli« iiiulcnilur girocfMes, so 
lltal (b« mm itf iH'n-iMis im^iulfo i» li-xci-ncil mid |iix>Ibn;;eiJ. llie vclocilT of 
ita patimgr Inriti}; niucli >tiniiiiiiibci). e. y.. (ntta 'lH metren to 1 metre |)er MCotuI 
At abiiui {)' C, ibr irritubililr of th« ni-rvc di«appear» allof^her. 

Wfa<-u a mitM'le u vx\».v*a to similar fold, <: 9., lu a tern) tern lure very 
lilltv alwiTe Kcro, llic eoiitrni:tiniiR are retnorkably prDlan;;ed : iliev ari; 
(liniiiii'luHl in bright nt llbc f^me timei bul not iu proporlioii to tbe iiicreaae 
itf tticir duration. ExjkimhI to a temperature ut'iero or b«[ow, niuM-ltn aioh 
loHtllHr irritabiliiy, wilbotit. however, imderKotu^ ri);or raorlia. AlW aii 
cspmirv of not inure titan a few eei-onda to a lemjienUurt.- not nm<-b below 
ibry may be mtored by Kraduiil wanutb tu »u irriliilik cotidilion, 
Uxiugb Ihey nuiy npitcar to bave been frown. Wlieii kc]>l froKvn, 
r, for aonie few luinuio. or when exputed for n IfM linir tu tcnipcra- 
tara* nf apveral degrees below iiero, ilietr irritability is ]K-riuaneiillv 
itHmytd, WlM>n al\«r tbn Ihey arc thawed ihey arc at firvt »uppK-, am), 
aa ve b«v« aeon, may )>e uituh to yiuld miiM-lu pliiMiii: but th<.'y ver>- 
ipwdily enter into rig<ir mortis of u lunM i>i\inoiincc<] cbaracl«r. 

1 8& Tlf I'nylii/Tiw 0/ biood-wupply. When a uiiaelo still within the hodv 

b ityrixtii by iiity nioBD* of lt» proper blood-«upnly, m when the hloud- 

vn«M gotag to it are ligntiirvd, tbe same i^adual loea of irrilabilily and 

tul ■npfliiiii of rii-nr ntiirlw nre ohsen'ed as in muscles ivmoved froin 

tb bodr. Thus if iKe alidoniinal iiurlu be ligntored, (hu miieelee of the 

kntr linba !<«« their irrilitbilily and tinally become rigid. ^k> also in sys- 

Hode dtatb, wheD the blood supply t<:i the miiacla is cut off by the oeasBtion 

of fhe dmilation, loss of irritabiliiy eiieuu, luid rigor mortia evoDtuallv 

r»|hiw*. In a human corpm the nuacla of tlie l>oily eiiU-r into rifpiT murii!' 

A m 6xrd order ; Brsi, thoae of the jaw and neck, then ihusM: of the trunk. 

MTt %hom of tbe anna, and la«tly those of the legs. Tbe rupiiliiy with 

tUeh ripH- motib ctomes en ufter death varies counderahly, Wxojt deter- 

■iaad tiotb by exiemal circumsluicea and by the iniemul i.»iii]i[ioa!> of the 

Wt. Tbu*, exifrnal warmth hnMcua and cold retard* ibe tmm,*!. AlVr 

(nat mtucular exertion, ns in hnnu^l auimal*. and when diiitb clowe^ 

•Mlin^ (li»*«»r», riiror morli^ in mort mm.« cumtv i>n rapidly. \t a i;encral 

nit, ii ttiuv Ih- Miid that the Inter it i« in making it;! appearance the more 

ffooouDcrrl il i», iind the longer it Instc: but there are many exception*. 

ad wbeit the >tiUi* i» n>c-ogiiiM-d a« boiiig fundamenially duo I0 a clotting of 

attain, it b eaar to undenlnml ihnt the amount of rigidity, ■'. f., the amount 

i/tbe r)ot, ana the rapidity nf the onset. ■■ «., the uiiiekiiesB with nhich 

>t«|palalioa tak« place, may vary independently. The rapidity of odh-I 

i&cr mutcular eser^^iK and wasting disease may, tierhaps, be in iiarl dejM'ud- 

won an iiH'Teaae of acid reaction, which ia produced tinder tnoee circum- 

*M(a U) the muscle, for thia leema lo be favorttble to the coagulation uf 

iWatutcIe plaama. When rigor mortis has once become ifaorougfaly ntab- 

b)M in a muscle through de|)rivalion of blood, it cannot be removed by 

uy tuh*eouetit supply of blood. Thus, where the abdomiital aorta ho* 

itnuinrd llgaiurtu until tlie lower limbs have beconte completely rigid, 



untying the lignliirc trill doi iv^tore tho miisolM to sn irritable coD<liti<ia: 
it feiiuply hnshrns the ilecom posit iuii of the deud tiaeues by eiipplyiii>; ihetD 
vilb uxygQa mid, in the ituic i>f thp mniDiDitl. wilh warmth aleu. A miucle, 
however, mny nciiiirt- us ti whole a certaio nmoiiiit of rigidity on account wf 
BOiueuf the fibres bpcoiiiing rigid, while the remainder, though (hey have 
lott iheir irritiibilily. have not yet advancerl intii riji-ir iJiHrtii*, At sucli » 
juncture ii renewiil of the bluod-siream may leaiore the irriluliiliiy of iltuM 
lilires which were not yet rigid, and ihua appear to do awuy wilh rigor 
mnrlia; yet, it appears that in sauh vanen Iht- tiliro which havr a<'tu(illy 
become ri>rid never regain their irritability, but und^r^o diiR-neratiiui. 

Mere liAi of irriiahilily, even thxiigh oumjiltrtf, if st<>[>pin)( *horl Df the 
Actual coagulation of the muj^cle )<iilHitun»>. may be with care removed. 
ThuD. if ■ Ktrcum of bUnvi he aent urtillcially through the vcffcU of » K-pn- 
ratctl (mtniinulian) niiiM^le, the irrilnbibty niay Ih- imiintftincd for a vcrv 
considomblc time. On Ht<>|)|)ing the artilicini circidntioii, the irritability 
dimiiii«hp« ntid in lime entirely dinappi^rv; if, however, the eimm Ik^ at 
once resumed, the irritability will Ih- recovered. By ivgulatiug the flow, 
(he irril«hilily mny he lowered and (up to a certain limit) ruiicd at pkiistirt, 
From iheeiioeb, however, of inlj'rfcrcnce with the normal b]o4xi-stivam thero 
is a gradual dimimiliim in the rcsponaet to stimuli, and ultimately the mus- 
cle KiBes all its irriuibilily iitid Mntmea rigid, however well the artitiiial 
circiilalion be ki^pt up. This fnilure is probably in great part doe lu the 
blood sent through the tissues not being in a perfectly normal L-undition ; but 
we have at present very little information on this point. Indeed, with 
re#])ect to the ^tiit/iVy of blocxl thus emeiitial to tlic maintenance or reAtore- 
lion of irritability, our knowledge is definite with regard to one factor onir, 
vii., the oxygen. If blood deprived of its onygen be sent through a muscle 
itmoved from the body, irritability, so far from being maintained, ^eeius 
mther to have it^ diiiappeanmce baHtened. In fact, il vem>u# bloud cun- 
tinncs lo lie driven through u miuele, the irritubilitv of the muscle is lost 
even more miiidly than in the entire abnenct! of hlooa. It would seem that 
venous blootl ii* more injurious than mine at all. If exbauv^on b« not 
carried loo far the muscle may, huwatver, be revived by a proper supply of 
oxygenated blood. 

Ine influence of blood-nipply cnnnot be so satisfactorily studied in the 
oaae of neim aa in the ease ol hium^Itv ; there can, however, be little doubt 
tliot tlie effects nre analogous. 

§ 86. TItr iiijtwnrr- oi Jiinrtinnnl arliribj. This, too, is more easily studied 
in (be case of musclcn than of nerves. 

When a muscle within ihc body is unused, it wastes ; when used it (within 
ccrtiiin limiU) grows. Both these facts show that the nutrition of a muscle 
is favorably aflecled by its functional activity. I'art of this may be an 
indirect effect of the increased blood-supply which occurs when a muitele 
contnietA. When a nerve going to a mitscie ia stiiuulalcd, the blood vawelii 
nf the muscle dilate. Hence at the time of the contraction mort bhiod 
flows through (be muscle, and this increased How continues for some little 
white ttA«r the uuntractioii of the muscle has ceased. But, apart from the 
blood -supply, it is jirobable that the exhaustion caused hy a ooutraetioii is 
imnteiliulely Ibtlowed by a reaction favorable to the nnlriuon of the muscle; 
and this i* a roMii, [Mwihly the chief reason, why a muscle is iucre«kM>d by 
use, that is to «ay, the ItMe of sulMtanoe and energy caused by the coiitnic- 
lion is subHK|ueiitly more than mode for by ini-rensed metabolism during the 
fallowing period of rest. 

Whether (here be n third factor, whether mu»:les for instance arc govcrued 
by >o-called trophic ncrx'ea which affect their nutrition directly in some other 



*ay than hy [iiSu«Dcin)[ cither tli«ir blood-siippi/ or tbeir aetivity, aiuM m 
wrai b* kn tiiiilf^-iitol. 

A aimelc, «v>-ii wiiliin the body, after prolaoK«<l action i* fatigued, •'. it., 
A MrmMr aiiaiuliM ix ivquirerl to ptMliice th« sami.' cuiUnitrliuii: in other 
woffik. Ua Irritabililv may Iw Itiwtiwsl by functional nativity. Wb(Hh«r 
fuartjuDal nrtiviiy, lb<'n-liirr, i< iiijiiniHi* or biini^fu-iiil ilci|Hiiibi on iCM amoiiiil 
in rvlaiifin to tb<' comlilion q( ihv muKck. It niiiv lii; here rcmurk^sl that tu 
a ntiacla bM-otim more anil more (btigucd, #lininli of «hort duration, Mich as 
leductioD-afaocks. looner h«c th«ir efficacy tlian do vtimuliofluiigdrdunitioD, 
tucfa M ibe break and make nf Iht- c^niitaiit curn-nt. 

IImi wnee of &tig»« of irhich, aRer iirolonged or unLieaal exortjon, we arc 
nMMemiu in our own b<idi«a, ii prcibably of complex orieiti. and its Dalure, 
hikm ihmt of the nonnnl luuBculnr ecitw of which we sliall bave to speak 
hsvaAcr, ia al preaenl ool thoroiiffhly umkralood. It seems to be ia the firM 
|d«ce tbe mult uf chaiigi^s in the iDUseles thoiDBclrGe. hut ia poauhly abo 
ewmd bjr changes in the nerroua apparatus conwrDi?<l iu muat-ular nclioo, 
aad ntMctally in thoae parta of tbe central n«r\'ou(i •j'sleni which are cod- 
oncxl ia the productiou uf voluntary iiupulaea. [n any oaae it cannot be 
ukrn na an ailoiuiite mciuure of tbe actual futisue of the muaclea ; for a 
■an who -■•y* he i!i iibaolutely cshauMed niuy, iitiJi-r ext-iicm«[it, pcrforni a 
my luge amiiuni of work uilh hit already weary uiuKtilcM. The vtill, in 
hcU niralv if cvi^r calln fnitb the grcaUH conlractiiiuii of whivh the niuccl« 
■n eapabfe. 

Awolul* (tcntpornry) cxbauttion of the mii»clo#, to that the strongeat 
■thauli product no coiilracitun, may be producnl even within the body by 
uMtiaS *iitniilaii<Hi : nwxvry lakm p)ac« on rmU Out of the body abwluU) 
tshttuKion lakca plan' n-udily. Hen.', alcr, itvovery may take place, 
Vbalber in any given aa»e it does occur or nut. ia determiDed by the aiumtot 
•d eoBinictMin atuing the exhaustion, and by the previous cnudilion of tbe 
Made. In all cases recorery it basleool by renewal {natural or artificial) 
«f iha bliHid-Alreain. 

Tbt BKtR rapidly ihe eootractiaQS follow eat-h other, tltc lew the iiilorval 
bitncn any two contractions, the more raiiid the exbauwiou. A certain 
nabar of ainuli* inductioD-^ooks rcpeateJ rniiidly, say cverr second or 
<Aanr, bring about •'simuMire Iom of irHlabiliiy more rapidly than the 
«as anmbw of aboclu repealed 1i>m rapidly, fur liiNtanw ewry 5 or 10 
wails, RcBM l«tanui ■• a ready mean.t uf pr>iihji'itig t^'x hiiuslion. 

!• axfaaiiMn) mu»cl4!« the I'hutticicy in much diniinislit-d : the tired muscle 
Miras Um n-ndily to Itn imiurnl U-uglh ihnn doc* tli<- I'mit one. 

The pxhauslitxi du« t» cunt nu-lt<m may be ihi' result either— of tbe con- 
■isMiitn of thr More nf ready ountrartilc material prcwnt <o tbe muscle; 
<4Hi tbr Bccnmulatiun iu tbe tiMiicof the proclucUof ibeact of oontraciJoD; 
«i «f both i)f these iwuet. 

TW rfMomtive influence of rest, in the caw of a miisclo removed from tbe 
limitation, may bt- explained by supposing that during the repoee. eitlier 
tti Bieraal chan^ea of the tissue manufHcturc new exp!i)t>ivc matenal out of 
Asopaiparalively raw material already pr«scni in the tibres, or the directly 
hnfiil pnnluols of the act uf coniracliuu undergo changes hv which they 
u» nMircrted into comjiAratively inert bmlies. A stream of fro>h blood 
«7 rxcft its reef>rative inllueooe not only by quickening tbe above two 
mat*, bui aim by oarryint: nfT the immediate waaie products while at the 
«M« linM II briitn now raw material, li in not known to what extent each 
•tthesa part* i* tOaynl. Thai iIh- proilitcta of contraction are exhauatiuK in 
tUroKcts, U sliown by the imiu that the iiiJM?ti<in of a a<dution <>( the 
aatdMXtraclivea into tbe vcwvls of a muscle produce* exhaustion, and that 



vxhaiisied inuBcl«* are iwovfrwl br the simple injection of inert snline 
foluttoue iiitn tUuir bloo<lve«ols. But tb« matter hw Doi ytl been fullr 
worked out. 

One iiuix)rtnnt clement brought by freab blood b oi^emi. This, u we 
have seen, i» mil ncc?<«Niry for llie tarrying iml f,{ Uie acturiTcAnmction, awj 
tct n et^e'iitinl to tb« maintciiaiice of irritiibility. Tito nxTgvn absorbed 
tnr Che mitn'k- npjiiireDtly ent«n in tome itet-uliurwuy into tlie fornmtiou uf 
tnat oomplvx irxploaivo niaterinl the de<^uiii[iiuiti(in'<>r which in the act of 
oontiaotioii. th<iiiph it jjives rise to caHxinic acid iind uthur piwduou of 
osidndoD, u Dot in ilwlf a pmcees nf direct oxidation. 

Thi: KxEBiiY OP Mt.>ot.i: ami Kkhvk. and the Natuhe or 
MlW-ULAR AND N'ERrotm AcriuK. 

§ 82. We may briefly revapitulaie »ori« of tho chief results arrived at iii 
thfi preoi'iling pngeii im followii : 

A inimciilur iimlraotinn ibH-tl' is MMiitially a tnu»loeation of moleoulm. n 
change of Ibrm, not of bulk. We cannot my. however, nnyibintc defliiiir &• 
to tlie nature of thi« triin«l(>cjition or lu to tlio way in nbich it h bnmehi 
about. For in»tiinec>vc cannot stiti«riii-Ioriiyexplnin the eoDiieetinii U-ttiivD 
the Htnation of n miisc-ular fibre niid u mtiiteiilur contTttetiou. Xritrlr all 
rapidly contracting musclee lire strinled. itnd we must aupixve tlint the 
BtriaCion m of Bonie use ; but it is not eweiiliHl to the carrying out of a eou- 
trnttion. for. as we shall see, the cunlraclion of a nun-Atrinled mtiacle is 
fumUiineutally the Manu' ti» that of a tiiriated iiiti«;le. Hut whatever be the 
exact nny in ivhioh the tiant^ioeation a ejected, it U in w^me way or other 
the result of n chemical cliango, (if an cxplnMv*! deconijKNiition of cenain 
part« of the t]iii>ck- KiilMlancc. Tho vni'rg>' which is expended in the 
niechaDiral work done by the muscle hiu< Itx Knurce in the eoerf-y latent in 
the muscle substance and set free by thai cxplonioii. Concemiiif; the tuHiire 
of that explosion we only know nl preecnt that it rmulis in the producli'jn 
of earbonie scid mid in an increase of ihc acid rcai'tinn, and lliai beat ii> set 
fVee.afi well as the specitic muscular energy. There la s general pnnillelism 
belwceu the extent of metabotiani uihiug pisce and the amouul ot eDer;gy act 
free; the greater the development of carbonic acid, the lai^r b tliccan- 
Iraction and the higher tlie temperature. 

It i» important to remcnitier thal.iui we have already uived, relnxalioo, the 
return to llie orfgiual k-nglli, i.n an ciiAeutial |>ari ol' the wnole cuntrn'tion no 
Ins thnn ihe yhdripiiing itjtelf. It Ik true that llie return to thv original 
Uinglb i]> H»»i9ti.-d by lh<- afri'lohiiig exerli-d bv the load, and in the cww nf 
aiUBclcs within the living budy ** nci'iired 1>y the action of aiitOgoniMie 
muscles or b^' vnrioux nnatomical relalidUH ; but the fact that the cotDptete* 
ncMand rapidity uf the return arc ilopciident on tlie cmiditian of the muscle, 
that is, on tne complex chuigt^ within the nnucle making up wbit we call 
its nutrition, the tired muscle retuxiug much more slowly than the untireil 
muscle, shows that the rnl&xntion is due in Ihc niaiu tii intrinsic proceMU 
going on in ihe muscle itself, proccsecs which n'e might chnmcteriie aa the 
reverse of lh«e of contraction. lu fact, to )>ut the matter Ibrcibly. adopting 
the it lustration used in g57, and regarding rclaxnliomutt change of molecult* 
(Vwm a " formatidU " uf one hundred in two lines of fifty each lo a formation 
of t«n columns each ten deep, it would be possible lo sup|>ort the tbesit that 
the rrally active foreo in muscle arc those striving to maintain the latter 
formation in columns, and thai the falling into iloubtc lines, that ts to aav 
the pontraetion, is Ihe mult of these forces ceasing to act ; in other wortf$ 




Umi iIm mMiinuMd atotc of tlw miiftcvlnr fibn> U what iokv hccnilod Um 
wUural lUte, tli«t ihc rclaxcl t-otulitUiti i* ntily hrou^'hl a\x>in »I tbn cxpctiw 
of ckaogM cnuHlcratrtiii); lite nnliirni [ondt'iicice of l}ic tiltro. Wilhout gofn^ 
■D Ihr M tliis, bowi-ver, we may still rpco||;niz« th&l iwth cuiilnwtion nnd 
nlazsUMi era the rmilt uf chnn^n which, niiof ihcy sccin to be of a cheitiicnl 
BHun in ibc iiiiv <.'iu«, nrr pmlMibly «o it) the other aJau. A>i<l thoUf;h in the 

iafai^Ma nf exact knowk<d);e il in (laiigerotis to speculnte, ne way iiuncioe 
thai ihtOT chemical events leiuliog to relaxation or elongation w of an 
ofio^U ttt BOtafonUtic cluinii-ter li> ihoae whoee issue ia coDtractiou. 
It luH not boen possible hitherto to draw up a complete equalioa between 
iW lalcBt enericy of the nislerial and the two fbrnis of actual enei^ set 
frw. bwU anil luovenM^uU I1ie pro^wrtioa of enerji^y Kiveu out aa lieat to 
that taking on tJi« form of work varies under different circuniiitauc«a : and 
it w<wM Bppou- tliiit iiu ihe whole a niuM^lc wuuld nut be much more i;lBoieiit 
tkaa a ttcam-eugiue in nwgiecl to the ronvenUm of rhcmical uctiuu into 
BM^aaiod work, were it not that in wann-hlocidetl aniiutilH tlie liMt );iven 
«nt b Dot, ai in tli« 8teaiu-eui;iii«. in«rc Iom, hut by k>'i>pii)g iiji tht- Miimal 
KapcmoK nrrea tnanj auhttiiliarr purpuM*. It might Ix' iiup|>tNH.Hl that ill 
aoMUfVcUoD by whidi work a actually doi», as RomptrttI with the Mow 
oaMtaetfcHi wh«n uo work i* doue. ibm >« a diminuiion of the increuM of 
tuipmturr (-urr«w|ii>ndlng to tli« timouDl of work d<>n<'. that i» to »y. that 
Ik* BWchonit-al work i* ili<ne at lb*- vxpcnM of energy which olherwis)- would 
ft D«it a* boat. ProWhk- as this nuiy ttvn, it has nut yot been expvri- 
SMMaJly verilWd. 

Of lh« exact Datiin* of the chemical chan^-^ which underlie a mutcular 
naUactkui we know viyry little, the must importaol fact bein^;. thai the ooii- 
indjoa m not th« outcome of a dirccl oxidation, hut the splitting up or 
tzplaitve d«ooinpontioi) of some complex suiiMaiice or Auhttaocea. The 
■Mil* dott ooDHine oxyi^n, and the pmducttt of muscular awtabolism are 
btW nd prodncU of oxidation, but the oxy){i>M ap|>eara to be introduced 
Kt It tiie niutnent of expl<itii<iu but ai some earlier date. As to the leal 
•Mm of th» exploBire material ne are as vet in the dark : we An uui know 
It (ertain whellier we ought to R-fcui^l it bh a sin^cli; suWtaiice ' in the 
ctmieal tenae) or as a mixture of more «ub*(Aiic» than one. We may, 
tnvvtr. pvrbapi be allowed pruvitionally to speak of it at all event* a* a 
ai|tk Mbataooe and to call it " cxmlraciile aiaterial," or we may ndo|>t a 
Mm vUeh hat lieen suggettei) and aill it inayn. 

W« iImII hare ooowon to i>i>int out taler on. that the hving stitwtance of 
ante nil* it abb lo aiaoutactiire and lo lodi^ in the tubetaiice of the ocU 
aWtaly eooakiarabk qiiaiitilicii at lat whcichy the cell becomn a fat cell. 
ibhl ao Jbrmed and lo<)gcd being sub«c<(uently by some means or other 
fcthafgnl from tliecell. Wo shall also have occasion to point out that in a 
■—■hit siuilar way the living material of certain gland cells nuiuulactum 
■■I 1m)(M id itacif ourtain nubetanece which, when the cell "secr«t«»," 
taimfi man or leas change and are ejected frum the cell. Theae suhataocea 
Mar to be produolaof the activity of llie living subataoce of the cell, and 
tobf *o telatod to that living substance that, though discontinuous with it 
oi urrrly lodged in it they are still capable of beiug mi iuHuenccd by it as 
h aai k i y o change more or teea aud<Wii. more or luu profound. And we 
^,ttao^oo theaaalof^of thenfiucelhiaud gland cells.auppnee that the 
hncnbaUuee of the muade roanufacturca and ludgtu iu itself this con- 
taw* taaMrlal or inggen which ia capoblo of lK<ing »» iidluenoed by the 
liiiiy aubMaDco aj to ui>dergo an «xp»(«ive decomiNMittou. But we here 
•Mwltli a difficulty. 
■ he tniMcular tlhre aa a whole in emineotly a niiro^cenouit proteid body : 



th« rniiiiculiir fibres of tfiv hoily riirni tlio greater [lurL uf the wliolc pmicid 
BUUK of the body. MiinHiv«r ihi; onltnnrj ooiitiiiutMl mcUboliMa of tb« 
roiiKulnr fibrv m ■ whole is «»i-nimllv ii uilrogciiotts meubolisiD : m wv 
Bbflll baveto point out luter on, th« muscles uiidoubiodljsupplyagrent i>art 
of that Urge oitrogenous waste which appears in the urine as iin^: th« 
nitm);eiioug metaboliitm of the muscle during the twenty-four hour« must 
lherffi.>ri? be con^idernble, and under ceriflin circumetaii(;ea, as for inMUDce 
during fever, this nitroceiiouB metsboligm may be still fbrther larftely 

On the other band, as we have already nhf>wn, there can tte no doubt lliat 
the act of L-outraciiou, the explosive decouipoaitiun of the tiio)^ii. iloe* not 
in«reaBe the nitro^uous metabolism of the muscle. 8hall we oonclude ihcn 
thai the inogeti ih ofiseutially a noo-nitroftenouB body lod^l in the nitn>' 
nQouf miiaJle ^ubniaucey Not ouly have we no positive evidi^icc uf thb, 
out the mmlugy lietween tontraelion ami ri|{or mortis is directly »p[>o>eil to 
lucl) a vi«iv ; for it U aliu<>«t impimtble to mist the voncluiiiou tluil thv >tu6r 
which givcjt riiw to the niyiwin I'lot, thu carbonic acid, and lactic acid or 
Ptlier Bcid- producing viibntaHOM of ri^or mortis, iii the same vliilT which 
giTC* rise to thi- trarbonic acid and Int-tic acid or otlicr add- producing sub- 
stances of n contraction. The dittcrynco Imwwn the two sc«ms to bo that in 
tli« conlractioii the nitrogenous product of the decomposition of the inojgMi 
does not ap|)car as mlid myosin, hut anumes the form of some soluble 
proteid. The imimrtant fact conceniing the two aclx. Hgor mortis and con- 
traction, is that, whilti the gn-at non- nitrogenous proiluct of the dccon posit ion 
of the inogen, m. carbonic acid, is simple waste matter containing no energy, 
fit only to be cast out of the l>ody nt once fand the same is nearly true of th* 
other non-nitrogenous product, lai'tic acid ). the nitrogenous produet being a 
proteid is '.till a body containing much onei^iy. whioh in the cu»e of tin* living 
muKcle may aAcr the contraction lie utilized by the mu^dc itmdf or, being 
carried awav into the blood -stream, bv ff>me other [larta of the body. 

But if ihU view be correct the ordinary melaboli.->ni gning on while ih« 
muscle in al re&t must diflbr in kind an well aa. and |X'rha|i» more thiin. in 
degree fn>m the nietftlwIiHin of contraction ; for thn furiner, a* wt have just 
nid, is (vM-ntially a nitrogenous luetabolisju largely contributing to tlw niiro 
genoiis waste of the bo(iy at large. 

Whether in the muscle at n-wt this nitrogenous mctalxdism it confined to 
that part of the inuncle in which the iimgen in lodged and docs not involve 
tlio inogcn itself. »t whether the iiio]^n an well as the n»l of the fibre (inder 
goes metahotism when the mnnclc is at rest, going olf in puflv, ao to apeak, 
instead of in a largo explosion, its nitrogcnouo factore being at tliesame time 
involved in the change, are •[ueetions u.*liich we cannot at prcoent settle. 

$ 88. While in muscle the chemical events are so pmminent thai we 
cannot help coneidoring a muscular contraction lo be ctwcntially a rbemical 
nroceas, with electrical changes as attendant phenomena only, the ease in dif- 
HKtit witli nerves. Here the electrical phenomena completely overabadow 
the chemical. Our knowledge of the chemistry of nerves is at preeent of the 
tcaiilieat, and the little we know as to the eheudcal chaii]t;es of nervous sub- 
•tanoe b gitini-il bv the study of the central nervous or^ns rather lliau of 
the nerve*. We iioil that the JrHlahility of the former is closely dependeni 
on an atlurpiate lupply uf oxygen, and we may infer from thin that in nervoua 
as in musciilamubataiiceauibtabolinm.orin the main an oicidalive character, 
b tlw real cause of the development of L'nergy ; and the axi^-cylinder, which 
as we have seen is matt probably the active element uf a nerve-fibn.', na* 
donblcdly resembles in many of iu eheniiual featurc:> the substance of a 
muscular Rbre. But we Imvc as yet no satiifactory experimental cvidctncc 


the pMMf^ of • nervous inipul»e aIoiik a oerve b th« rwull, like iht 
eootncckn of a maBculBrfibre.orcl>einicalcJmDgt«,aii<l like it ncooinpuikd 
bjr aa crolntioD of beaL On the other hand, the electric pbenonieiui arc no 
pVDiniiM-nt that Aonie have bceu ieiii|iie<l to reftHnl u iiervuiiii impiilxo lu 
■aaninllv an Hwtrical chaugo. But it ihukI be reniomhertyl i)inl tbi.- uotiml 
•oamr IM ft«e in a utm'uua iinpiilao if, wi to njiciik, inHigDificuDt, no tlmt 
chllWiul fihaaita ttiu iiliichl to be n-oignixc)! b_v tn<? incnriM at pitaoot at our 
di^jMil MtniM limply Muflire to pmvitle all (he i-iH-rgv net Im*. On thv otlivr 
imiui. the rnlc of' Imiutniiwion of a nervouo impiilHi, puttine aeidp other 
telBraa, M aJoot aufllcim to prorc that it is nomelhiiiK quite djflercmt from 
M onliiMTT electric cum?«t. 

Tbr ininiiu* ilt*po«iliun of ihu cml-platoi, an<l their rcmnrkable annlogr 
with the elvctric organ* which arc foiiDd in certain animalB, haa suggc^tM 
th* new that Ihr jNUMige »t' a nvr^-oui impulse from the nerve fibre iDto the 
nuuvalar mbitanoo ie •>(' the nature of an electric (lisebarge. But ibeM 
■Mttra are too difficult and too abetrufie to bo discuawd here. 

tt nay, however. )>« worlh nhilo to remind th« render thiit in every cod- 
tnrtioDof a luurcuiar libro. the actual change of lurm U preccdeil by invisible 
tlaagn pruiaigat«cl all over the libro and occupyin)* the laleiil j>eriod. aod 
llal tbci* fBangea reaenibie in their fcaturee the nervous iiupuUe of whiob 
tbrr are. fo lo fpeak. ihe eoutinualion rntlier than the coniraetion of which 
t^y nn* the forerunu«rB and lo which they give rise. So that a muacle.evei) 
fMuiif aaid« the risible i«miinatious of Ihe nerve, b AiudsmeDtaliy a 
■Mill sad a ncm bMidaa. 

Oa SoHB OriiER Forms or Coktractilk Tib»vr. 

Jlain, Smcolh or UnttriaUil Mtumtar Tunie. 

t W. This, in vertebrates at nil ovcnt«, rar«Iy occurs in isolated maoseaor 
aaRba, aa dam striated muscular tiwue, but is usnally found laking pari In 
litMniolure of complex orifabs. such for iiietanee as the intestines ; hence 
tW inveMi|[atii>n of its properties i^ beset with cuaiiy diflicukiea. 

It ii mually arranged in sbeels, composed of flattened bundlca or bauda 
h«ad InKBtlwr by connective liiHue earrying hloodvea^eU, lympbatiua, and 
tmn. SDiDe of these buudles or baD<ls may be split up into ^inallor batid* 
aailarlr untied to each other by o'ninective listiue, but in inaiiv cnM« thu 
•Ua ^oet being ibiu is made ui> directly nl' small bauds, h^ach tniall 
imi is oompowii of a ouniber of elenieiiiary fibre* nr tilire i-elU, nhidi in a 
nnaiti aetiac ar« analofroui to the atrial^ elementary iibr(r:<, hut in many 
Mieetf diOer uldcly fmrn tbein. 

Eadi uiWrtaleil tlinneDturv fibre is a luiuute i>bject, from 60 „ to '200 ^ in 
impk and fmru A ^ to 10 /• tn breadth : it is therrforci. iti «iz«. of a wlmlly 
wnmt nnler froB) a Ktriatod fibre. [Fig- 4.S.I It is futiform or epindle- 
^pr<l, •otnvwhal fiatli-iKil in the mi<ldTr ami tapering to a jxiint at the 
Md*. ahich In vume <■■■««> are branclivd; but the exact form of the (ibrc 
aiii (UHor according as the muscle is in a Mate of oootraction or relusation. 
Hidirny between tbo two cndo and in the centre of the fusiform body lies 
■ uelaiu. which in a numml randition is elliptical in outline, with its long 
■SB Inni; lengthwiie. but which under the influenoe of reogeala ia vary 
^^ Utto b eeowe rod-shaped ; hence in prepared specimens the pnseooe of Iheae 
b Mifca p ed nuclei u very cbaracteTctttic of plain mu^ular tiauie. 
H 1W Buoleus baa the ordinary characters of a nucleus, and rery fre- 
H fMMly two nucleoli are coospicuouo. Around the nuoleui b gather«<l a 




UuMiK Akirhw: I. fn>m ihv 

pupQIMl arlorr ; <t.Bllhniit ; b. 
wllti Rcollc Mid. i;frani * loanch 
or thvaalvrinMIbUl ; a, iiucJoi of 
(be Bbni (mwdUlwl SM llniei I, | 

nmll '(onutiiy of grnnulnr jirotuplajiin, like tlmt around the niiolei of k 
Uintetl fibre, and this u C(>(iliiiut.-il alori>: the uxU of the fibre for somo 
(Ibtlimce from vticb jHtle of the nucleufl, gnid- 
tinlly (n]>«riiig uwav. and so formint; a Blender 
grniiiilnr crn-v in the median portioD of the fibre. 

Th<- n»i iif tb« fibre, fi>nnin)( its chief iNirt, is 
cumjiuMd uf II tnuiHiiurcnl but sonteulinl refrucrlive 
RuWtitnoe, whieh i:< either homo^ciicouiiurexhibiia 
n delicate loiigttiidionl libnllutinn ; tliiit i» tiit 
muRclo •uljBtnntc of the fibre nml <;orni«fK>n>li> lo 
ttiG ti>u«cl« eiitwtnncc of lh« 9triiili.>d librv, btit U 
not striateil. Sometimct the whole fibre it tbrofrn 
into n »erice of tr«ni»vprw wrinklw, wbicb give 
it a eirinted appcnrnnco, but this in n very dif- 
ferent Btrinlion from thiit producml bj an alterna- 
tion of dim anil bright bandi. No »m'h allerna- 
doD of ban<l» if lo be feen in tho plain miiBciilnr 
fibre; the whole of the eubelance of the fibre 
around the nucleus and cure is homntfeneoua. or 
at leaat exbibiis no diflereutialion beyond that 
into fibrillie and intertlbrillar xubstance, and even 
this distinction ia doubtful. 

The fibre has a sharfi clear outline but is not 
limited by any diiitinct sheath comeapondiug to 
the sarcolemma, at least according to mo«t ob- 
It ia obrioue that the plain muscular Bbre i» a nucleated cell, the oell oub- 
stance of which has become diRcreDtialed into contractile sub«tauce. the cell 
otherwise being but slightly changed : whcrNU the niiich larger slrialcl fibre 
is either a nutnlier »t' cclU fu>-ed together or a ucll which has undergone 
multiplication in i>o far thai its nucleus hn» given rise to several nuclei, but 
in trhich no diri»ion of cell »ul»lance has taken place. 

A number of such fuHifonn nucWied cells or libree or fibre cells are 
united logellicr, not by connective tissue but by a |>eculiar proleid cement 
aabnaooe into a tial band or bundle, the laperinj; end uf one Bbre dovetail- 
ing in between the bodies of otiier Hbre^. 8u lun|{ as this cement eubsuinee 
is intact it ia very ditiiculi tu i^nlate an individual fibre, but various reagents 
will dttoolve or la^iwn ihi.H ceiueni. and then the fibres se|}arate. 

Small flat bandA tliu« formeil of fibres oeoiented together are variously 
amneed by mciiiia of cunnective tissue, sometimes into a plexus, sometimes 
into thicker birgt-r bands, which in turn may be bound uji. as we have luiid. 
into shccl» of varying thicknoM. 

In the pIfxuB, of cnunn', the lumda run in various directions, but in tlic 
Rhe«ls or meinbruiio' they follow i<>r l)ii> most part the sntiie direction, and n 
thin tninsvciw section of a winwwhnt thick sheet presents a number of 
smaller or larger areas, oorrt«ponding to the smaller or larger bands which 
are e»it acroe«. The limits ol each arcii arc more or less clearly drlim-fl by 
the connectire liseiic in which bluodvcsietB may bo seen, the nrcji itself being 
mnpoeei) of a number of oval iuiltiii»i, the soctionis of l.hc flattened indi- 
vidoftl fibree; in hardened specimens the outlines may from mutual pmaure 
appear polygonal. In the centre of some of these sections of fibres the 
nucleus may be seen, but it will, of course, he abseut from those fibres in 
which the plane of section has passed eitlier above or below the nucleus. 
When a tliin sheet of plain muscle is spread out or leased oui under the 
mierovrope, the baiKls may also be recoguixed. and at the torn ends of some 



of Ifcc Iwncb tlie imlivUlual fibrec nur Iw >ceu prujcctiag nder the fashion of 

BloodnMeh mud lymphuioi are nrriwi by lh« conDoctive tinuc, uid form 
owitUry networks and Ivmtihatic pWxu»n> round (h« ainiillvr bands. 

1 M. Thtt anaiig«aM-(if <■/ llw norvm it) unmriatcd muscle difRtra from ihat 

in (tfiaivd muncJe. WhcnMic in Mrinlci) miudc mcdiillated tibree ooiuin); 

dina tnta tltv anterior mnUi nf #{)4nai nerves iiredominale. in plain muitcle 

OW ■xdllUaUd fibrv« urc iD<wt abuodnul ; in fact the nervw gaiDg to plain 

OismIm Mv not only smnll but are nlinoet exclufiively (.■omtmaed of uvii* 

nHdollMad fibfee aud conic to iIr- miisclefl frum tbe Bo-cul]e<i lyntpaLlieiic 

mum. Pawng ■ut') the coanectivc tiwuc betweftn the bundlea th« nerve*) 

•iiiidt>aDd,ji>iiiin)^ ngmin, fonn b plexus around tbe buudie«; thai is tAiuiy, a 

t«ig conxiftiHK of a few, or perhaps only one axis-vvliuder, coming from 

bfaocb will mn alougside of or join a itiniilar «mall twig »>miiig from 

Itmich ; ibe individual ax ia-cy linden, however, d» noi thcjaiwlvM 

Kriim sut-b prinmry plexuiu, in which u few mrdulbiuul tibrw 

H« pnaeol amoD); tbe iion-miKliillaied tibi^, arc given ofl'Mill finer, " inler- 

Mfiluie" plexuses oiiwtAliag excliisivclv of nun -mcdiillaiod f;brc« : thm 

fb »»e e ths smaller bundle* nf rou»ctifar fibre*. The branches of those 

flkmmm majr oonaiat of a lingk axi»-cylinil<-r, or may even be (ilamenla cor- 

Mpoadins to several or a few only of the librillie nf which an axis-cylinder 

i> Mppneeo tn be coAiposm). From thwc intvrmwiiacc plexuses ore ;>iven ofl* 

■i(ie (brills or vcrv small tiiiodlt* of Rbnllir, which running; iu tbe ceraeni 

■fafance between ibv iti<lividual libru form n Kiie network around ilie indi- 

titaal 6bn», which network dilfers frcini the plexuses just spitktu of, ina.4- 

nneh M sotuc of tli« fil»nivnl« composing it nppear to o<ialeK«. The ultimate 

MlbiK of this network has not yet been conclusively traced ; but it *eem> 

■ntaible that fibrils from live network lenuiuate in imiall knobf or oirellings 

tfiaf en tbe subsUuice uf the muM-ular l!breii, somewhat Jtdi-r the fn»hion of 

■imile end-plfllea. 

A timilar temiiDation uf nerven in a pk'xiu or network is met with in 
mW tisaues, and is not cimtined to uun-ni«dullaud fibre). A mc^liillated 
fln may end in a plexus, and when it does ao loses Jinit its medulU and 
nAis^flentiy it* neurilemma, the picxu* becoming uUinint<tIy like (hat formed 
ha Dun-mtdullntcil fibre nml con»i.'>liug of attcnusictt axis-cyiinilers with 
uiokmin^ nnd Htmrliniiv with wuctci. at the nodal points. 

itl. As far n« we kimw, plain nui »cii hi r tissue in its chetuical features 
nmaliln strinlt^ muscular tiwuc. It cinltiins nibumin. Aoine formn of 
dthslio. and anieeeduts of myosin which u|>on tlie death of the fibres 
Mine mronn ; for plain muscular tissue after death heoornes ri^'id. losing 
h WenribilitT and probably becoming' acid, ihouj^b the aetttity \* nut M 
■vfcnl as in ftrialcd muscle. Kreatin has also been found, m well as 
fl^fogva, and, indeed, it swais probable that the ftbole metabolisoi of ptab 
nmtar tisaue is fundanwntally tbe same as that of the tttriated mueoka. 

t n. In tlieir {general physioal feaUiru plain muscular fibres nko reeemble 
^risioi fibres, aiw) like tneni they are irritable and contracltlc : when sUinu- 
htol ibey riinlraet. Tbe fibres vary in natural length in ditforont •ituations, 
ikss of the bloddveiMla, for iiwtjiuce, being shorter and mouivr than thoM 
W the intmtiu« ; but in iW name vituation the fibres may also he found in 
*• af two diflereul rvMiditions. In the one ouc the tibna are long and thin, 
h lh« Dthrr onse they arr reducr<l in length, it may he to one-half or even 
*f •ae-thirr), ami are c«)rr«wpoudingly tliioker. hroiuler, and Ins poinicxt nt 
Asiadf, their total bulk remniuiiit; unBlCered. In the former case they are 
nknd or elongated, in ihe inlter caw tbey are conlractctl. 
Til* bets of the ootilractioD of plain muscular tissue may be studieal in 



tin inUMin«, tbe miiacular coat of which coiiHists of an uttter thin aheel 
oompoaed of fibrea ajid bundla of tibree di9jioi«<i lonfptuiliiiiillv. ninl of on 
iunerniucb iliicker sheet of flbres dispoBe^l uircularlir; m the uratera similar 
«rnui]^tii<.'rii of two coatA oblaiu^ 

If a mechaDJcal or electrical (or, iiidted. imv uiher) ftiniuluK he braufiht 
to bear <mi a [tan of a fre^h. living, still wurm iiiluiliiie (the >mall iuKwIim: 
is th? Kitt to work wilh) a circular cijriU'ticiiiiii i» Mxn to take place nt the 
»IKit iiliniulated: tlic iniisliiie »eeiu» nifiiHMl in ringwJM;, n» if tied miind wilh 
an inviitiblf coni. mid llie [larl »ii CDiistriitcd, previously vascular and red, 
becoueB pnlu and bl<KiilIra». Thr individual librcs of ibe cm-ular oooil in 
the region stimnliited have ruch htnyime :<h()rtcr, nod the total effeei of ibe 
BhorteniD); of the mullitude of fibres all having the same circular di8|>06iti«ia 
is to coDiilrict or narrow the lumen or lube af the ioteetine. The longitudi- 
nallv dispoiied fibres of the outer lon);i[uiliDat coat will at the eame time 
aimilarlv contract ui i^horl«D in a loDjfitiidtnal ilirecliitn. but (his coal Iwio); 
relatively much lliiutier than tbe circular coat, the lonKiludiiial coolractiou 
in allojiitfiher oveti*hadowed by the circular cunUacliun. A similar mode of 
»iniracti<m u also aeeu uheu the ureter is oimilarly stimulated. 

Tliv contrnction thuit induced in preceded by a very Iniix latent (teriod and 
lu»t> a very coniiidi^rnhle time, iu fact, several seooiitb, after which relaxa- 
tiiin (lowly takni jilace. We may »ay tlieo thnt over die Hrculnrly diitpor 
fibres of tbe iiitentiiie (or ureter) at the spot in queittioii iheri' lins pawcdj 
conlmction-wavc remarkable, fur it« long lateJit tn-riod nnd for the tlowiii 
of it* dovcl"[)mcnt. the wave being propH^tcd Jrom fibre to fibra. From 
tbe »pot so directly stimulatnl the cx»ntraetion may piw also as a wave (with 
a len^'lb of I cm. and a velocity of from 'iV to ■in millimetres a second in 
the ureter), along tbe circular cont both iipaard* and downward*. The 
loofptudinal 6bres at the sput stimulatefi ari>, ns we have nid, also thrown 
into contractions of altogether ainiilnr character, and a wave of contraction 
war tbiu also travel longitudinally along the longitudiual coal butb upwards 
and ilowun-ania. It is evident, liuwever. tluit the nave of contraction, of 
which we are now ii|)eai(iiig. u. in one rt^jieet, dillereut from tbe wave of 
ciintraetiou lrcate<I of in dealing with tilriaietl miUK'le. In the latter i'AM 
the ci>ntraet ion- wave i.-> a sinijile wave propa^iUid along the individual fibre, 
niid starting from tbe I'mt-philo or, in the ciim> of din-ct stimulation, from 
the ])art of the fibn- first ailectiil by the otimtilus ; wc have no i-vidcnc*^ that 
the c-untniction of one film- can communicate conlractinn to neighboring 
6bres, or, indeed, in nnv way inHucnce neighboring fibres. In iho case of 
tlM inUAine or urel«r tltc wave w complex, being the sum of the cuntmcti<Hi- 
WSTCS of several fibres engaged in <liliercnl phases, and is propagated from 
flbre to fibre, both in the direction of the fibres, an when the whole circum- 
ference of the inteetiue is engaged in tbe contraction, or wlien the wave 
travels longitudinally along the longitudinal coal, and also in a direction al 
right angles t<i the axes of the librea. as when the con tract ion -wave travels 
lengthways along the circular coat of the intestine, or when it paaies acrots 
u breadth of lite longitudinal coat ; that is to say. the changes leading to 
Ooniraction aiv communicated tint only in a dire<a manner across the cement 
■ubslance uniting ihir fibri-s nf a liundtr, hut also in an indirect mantKr, 
probably bv nieaimof nervi- fibri^i (Vom bundle to bundle acniwt the connvctive 
tissue between them. Moreover, it is obvious that even tbe oont ruction -wa\-v 
whidi i}n»^ iilorig a single unslriatcd Khre dificrs from that pamiiig alone a 
frtrialed Kbrv, in the very great length both of its latent jieriod and of the 
duration of its contraction. lieiice, much more •.■VBit than in the ciue of ■ 
Striated muicle. the whole of each fibre must be occupied by the contraction- 



v«v*, ud. iodAet), be in nearly tli« mine phase o( tlie coDlractivn nt tbe 

\^*an* of DODLraolioD tbiu puwiiiji aliinc U»e circular and loiii-iluduia) 
k ■>f ibe iniesiirw! raoBtiiute irtiat b (-allt<il pemialiic at-tioo. 
jk« xhv <i>iitracti<JDi of vtrimlMl uiU)M:Ii.- the coutniclioua uf plain niuecles 

\t b» »t*nin] hy ttimulKtiuti of uiu-vtn ic^ng tu the part, the nerrea sup- 
|i}ilif plain niiiMaUr tilMie. ruiinin); fur tlie most [tart, u ne tiave said, in 
tbir*»w)e(l *yn>p«lbetic kynteni. but being, ox ni- iiball M-r. iiltiiuutelx c»u- 
DRWd witb thr kpinnl cnril or brain. Hi-iv, Ii<iwev<:r. wi- runiu upuo au 
Ifiiilllil dUlinrlHrn bHwm-n ibv ntrialnl nkclttal niuoi.'U'H, ami the pluiu 
■wlw of tlM' vMconu Af a ^ncrnl niliv ibc AHt-liil niuiu;lt» art; thn>wn 
iUm cvintnaninD only by n«rvou' impnli>e« rracbine them ubin^ thoJr nerriM; 
ifMUuMMU tnuvvRicnis of tho i^kclctiil nuiBclra. ibat h. contraction* nrlalng 
nuof changes in the musclca lh«inM)v«8 are rstrcnicly rare, and whcii tboy 
genir atr abnormal ; au-called " cramps '' for Instancf . which are pnilvngvtl 
Kinir i.-iint rati ions of skeletal inutclea lodependeDt of tlio will. tli(>U);fa tbeir 
Kttmae* w larvelj due to tbe ooudiiion of the muscle itself, genernlly the 
mull (if overnork, are probably ai'tually started by ncrv<iu» impultee reach- 
bctbcBi truiu without. Un llw other baud, the plain muaclcs of tbe viscera, 
(f ^ blflstJiw. uteni*. and ureti^r, fur iitMunc«, and uf the bloodvcMeU very 
bi^wntly fill) into coulractioiia and ao carry out movements of the organs 
u> whirfa ihey belong iguile {nd^JcndcDtly of the central nervous aystem. 
Tltar (irgiaoi exhibit " 9j>ontimeou» " niovcmenU <]uite apart from tlie will, 
ipirapttn from tbc tvntral nur^'nun *y#ten), and under favorable circum- 
tiBtm continue to do tht* for »i>m« time after thev bav4- been entirely isolated 
■d rmuvnl from the Univ. 80 slight, indeed, ii the connection betweem 
■hanaranaitt of oi^ns and part* ^lupplinl nilb pluin miii'i-iilur fibrea and 
inW, lluit thcae muKtilar tibrea have ometiince been called involuotaiy 
aoitiB: but this name ■• undesirable. since some muwlM GOOneting eiitirvly 
dftma moacular librea (e.g., tlie ciliary muHclea by vbioh tbe eye is bccoiu- 
MataJ for riewing objects at ditl^renl diatancw) are directly under tbe 
iMiimwe of the irill. and some muaclea conipoeed of striated Kbrea (c. y., 
iha* of the heart) are wholly removed fhint tlie influence of the irill. 

Va ihall bt&i siuily. Imweror, the facta relating to the movements of parts 
fnriiM with plain iniiacular fi bras, when we come to oonaider the parts 

UId* the skeletal mu»clc», vdioec iwr^'ous element* have t>een rendered 

fcHtiooally iDcn|iable (i 78), plain muscles are muoh more iwnHitive to the 

■king and breaking of a constant current than to induction nhurks ; a 

~1|irat, kIwu very bnof, like that of an induciion-iJiock, produce* little or 


Thc plain iiiuxrlfla iMm to be remnrknbly aufccnlible to the iiiHiicnt-cs uf 
lm[irratiire. When exposed to low Umpi-tiitun^ tiicy rcndily low ihc (inwer 
*f minrttDg : thus the movements of the intcMJnc nri' »iiid to ccim;' at n 
ImpamUire below \it° ('. Vnriatii>n< In tcmperaiuro have aU'> very nmrked 
•fnt nn tlwi duration and extent of the contractions. Aaaocialcl probably 
tah thi> susceptibility iii ibo rapidity witb which plain muscular libra, even 
b eoU-blooded vertebrates. lo»e tlieir irritability after removal from the 
M* and severance fmrn their blood-supply. Thus while, an we have seen, 
Ikticeleial muaclea of a frog can be e3C[)eriitiented upon for many lioun (or 
nw fit two or three dava) after removal from tlie lutdy. and the skeletal 
■■ ■tia of a manmal fi>r a much lees but alill comitlurable time, it !• ■ 
WUffnf rrry gnM dilficullr to im.-cuiv the c<intinuu»cv of luovemeoi* of 
AtiuMtine or utherotgans supplied with plain iuu>culnr librni. even in the 
■Msf Um ftog. for any long |icriu<t after removal from the body. 



TIm contrnoiton nf nlnin muttrtilitr fibres is, u w« said, very ilnw 
dvwlopmeiit iiiii) very long in it» ilurttlion, orcn wh«B sUrtmJ liy n ni'tiiirii- 
tmry atimuluR, such ru n einglc inductimi-shoclc. Tho contriK-tum :illor h 
MiiauUtion often ImU so long w (o rniso tho qimtion, wluttber irhRt liii* been 
produced a not n single contraction but a tctttniis. TebiniiE, how^riT. thiit 
IK, the luaion of n eeriei^ of contritctions. weins to be of rim occurrence, 
lhou;;h probably it may be indoceil in plain muscular tiaasuo: but the eadt 
of leianus are gained by a kind of contraction which, ran or ni lead not 
prominent in skeletal nuiecle. beconiea of great importance in plain musculST 
tisaue by a kind of coiilracliuu call«d a (onie contraotion. l^ie subject is 
on« not without difficultiett, but tt would ap(>ear that a plain muscular fibre 
inay remain for a very considerable time in a state of oontractJuu. the 
amount of «liurt«oiny thui maiiitaiTied bein;; either sniull or i^rcau ; it t« Iheu 
said to l>e in a ttLale of tunic contraction. Thin ta eapcciallr netm in the c»»e 
of tbu pluin muHciiIitr tiiuiue iif lh<! nrtt^riu*, and wc shall nave to return tv 
tb!« matter in di-aling with the oirenlnlion. 

Till- inusnilnr liivmi^ nhich enters' into the ooniiU'uctton of the Ikcart is of 
a peciilinr nature, bi-in^ on the on« hand iitriutcd and on the other in aftinB 
nisneet* Mmiliir Ui plain muscular tiMUO, but thi» we Mhall considvr in dcalii 
witn tho bmrt itself. 

Ciliartf .VoweHiwif. 

^ 93. Nearly all the iDovemeot« of the body which are not due to phyiic 
causes, such as gravity, the diHiiftion of liqnida, etc., are carried out by mus- 
elee, either striated or plain ; but some small and important etiecu in ibe 
way of movement are produced by the action of cilia, and by those cbaugcs 
of pruloplasin which are <-alled aniiebiiid. 

Cilia nro generally n|>peii<lai[t!.H of epithelial cellit. An epifhrlinm cnn*ii)ti 
of a number of cellit nrrangefl in a layer, ono, two, or more celU deep, the cell 
bodies of the coiKtttucnt kkW* being in contiict with each other or united 
mcnly bv n minimal amouiU of wmeiit onWlanee, not «panilc«l by nn 
aj>preciable quantity of intercellular material. As a rule, no conoc^rtire 
tosue or bloodvcasef pni«M between the cells, but t)ie layer of cell* resU on 
« basis of vascular connclive tissue, from which it is usually separated by a 
more or lens definite bnscrnenl membrune. and from the bloodvenolsof whjeb 
its cells draw their nourishment. The cells vary in tbrm, nod the coll body 
round the nucleus may be protoplasmic in appearance or mav he diHenenti- 
aled in various ways, An epithelium bearing cilia is eafled a ciliaieil 
epithelium. Various passages of the body, such as, in the mammal, parts 
of the nasal chambers and of the respiralory and generative passages, are 
lined witJi ciliated epithelium, and by the action of cilia fluid couiuiniiig 
rarioin panielm und ttt^uemllv nior« or less viacid is driven outward along 
the pamagen tnwnrd the exterior of the body. 

A typical epithelium cell, .-luch nn may be found in the trachea, is gvne* 
rally sumewhiil wedgushajied with its broad end circular or rather polygonal 
in outline, forming purl of the frcR surface of the rpitbcliuni, and wilh tie 
narrow end, whieli miiy be n blunt point or may be somewhat hniiiched and 
irrvRiilar. plunged among small subjacent cells of tho cpilhclinm. or renching 
to the ciuiticctive lii»uc. Iielow. 

The cell body is. over the greater purl of its <'Xt«nt, composed of proto- 
|>lasm <Tilh the usual gniniilar iip)>cnrHnce. At nbout the lowcrthird of tfa« 
cell is pluced. wilh ile long aiiis vertical, an oval nnclens, having the ordi- 
nary cliaraclere of n nucleus. 80 far the ciliated cell resembles an ordinary 
epithelium cell ; but ilie free sur&ce of the cell is forioed by a layer 


kysliM trnospareut soroewluit rvl'niciiv« (uUunw whinb, whtm ih« nil is 

MP. M unuftl. ill profile, mppt^in n n hyiilinc rpfrnrtivo bnEi<l or bonier. 

VroiB U)i« b<iT<lt>r ihi'rc |inij««t ouiniiril n VAiiiibln niiiiihi.T, IC t<> -t'.), tklU 

nttr iBpmnfc liair-liko tilftmeoM, Tnn'ine i» l<'ngih, but gvmi-rally nboiit ii 

•(tiuUT or ft tliini u long U Uio eolt ibwlt'; thcw arv the i-ilia. liiinKtliatcly 

Mu« llii* hy«lini:! lM>nlvr iW orll Fulwiuictt often «xhibil» more or Imr ilis- 

tbetly ■ luaKitu-liiuil ftrmtiuti, lini.- linos pM§ing down from ibe hyaline 

V lowHnf the lower part of the: cell euUtetici' mund the niicloiu. Tim 

bordar itaelf asuallr cKhibiti^ a striatiaii as if it n-ero split up into 

■rh block corresponding to one of ibe cilia, nod c«re(ul examitia- 

liM loMfa to the conclusion that ( he hyaline Imrder ia really ooinpoaed of tlie 

Ibtd tbiokar baeal parts of the cilia. 

Hi* mail body has no distinct external luenibrane or envelope, and its sub- 
KMCf is in close cuntact with that of its iiei|;hbor», beiuK nnited to them 
albcr by B tbin layer of Mine ceiueiil substaooe. or bv the siuiple cohesion 
«f ibHr rutieclive surfiices. At all events the oetlfl do cnhere laif^ly 
ii(Hbcr, aii'l it 'm dilficull to obtain an itolntcd livinf; cell. thou)[h tlie cells 
uy be evily *cparaivU from each other when dead br the help of diMooial- 
iif lluMii. WbMi a cell in obuitued is»]ut«l in a living state, it u very 
twiacatlT fwund to hare Imi iu ncd)pi fhii\v. and to hari; become more or 
^Jb htnjtpberictl ur oven Htibcrii-al ; undi-r the Utnal cxiditiuns, and fre«i| 
^|Bb tlw Mpport of its ncigiibon. the cell body change* it* f»rm. 

^rksgnMralcharactenjuKt'liwrilmlnreooRinion toall ciliated cpitbeliiiui 
(ilk Ml lbs cell)) in diircrciil niluntiouH vary in certain |)articular«. nivh as 
Asritrl form of the cell IicmIv, the number and length of the cilia, etc. 

I H. (~iliar}- actinii, in lliv ionn in which il is moM common, in mammals 
ud. iodei-d. vi-rtcbrsle*, consists in tlw cilium ( ■'. r.. th<^ tsfierinp tilamvnt 
ifiikto of alxtvc I being at one tnomeat straight or vertical, at the next 

w t b«ia;c beni <loivn suddenly into a houk or Dii-kle form, and then more 
4mh returning to the straight erect ]>oailion. WIteu the cilia are vigorous 
Ail double nwremeni is repeated with very great rapidity. «(• rapidly that 
4r indiridnal movements cannot be seen : it is only wlieo, by reason of 
favun, the aotioa becomes slow that the moveraeat Itself can be seen ; wliat 
itsMo iithtinriTC b simply tbe efltrt of tl>e movemenL The miiverucnis 
ttsBslow hnvv lM-enc»unied at about eiubt (double nuyvetnenis> in aseciind; 
imMkly when rigonxn they are leiNuiteci from twelve to twenty tinuv a 

IV flrxiot) lake* ntim' in one dircctiim only, aixl all the cilta of each 
mI and. indrvil. of all the cell* nf tbe name epilheliiini ni'ivc in the safllO 
AiMfioo. Moro')vi>r, the Mtmc direction >■ maintnimil itiiring Uie whole litiB 
rflheepttheliuoi; thuo iho cilia nf th<^ epiihelinm of (hit trachm and bmn- 
■Ual oaaagaa more during the whole of life in »ueh > way ss to drive the 
JaU Ijrlng opon them upward toward th<- mouth; a« ftir as we know, in 
rsias, or at least in mamiDals, the dirvction ts not ai»(l cannot by any 
be rweneil. 

TleBexion it rm- rapid. Uiil the return to (he erect |>i>^ition is mneb 
ikmt; hence the total etiect of the blow, supposing the ciliiim and the cell 
)*)|« Used, is to drive the thin layer of lliiid in which the cilium is working, 
•kl which always exists over the epithelium, and any {)articlf» whidi nuiy 
Wfinstini; in that Huid in tite same direction as that in which the blow ia 
fina. If (he cell be not attached but Hoatin^ frv« tbe eflect of tbe blow 
aav bs tu drive the cell iLwIf backnanl; and when perfectly freali ciliated 
rfiibiiuni is b»aed out and examineil in an enen fluid, such us nurmal 
alia* fciliitiuu. isolated cells or amall jft^ups of cells may be ween rowing 
Asodves about as it were bv the action of their cilia. 



All th« dim of a od) mov«, a» we liave juttt Mid, to tilt mow dtTtntioil, 
bill net <iuile nt lite aaoi* time. If nv cnll llio siclv of the oell townril whkb 
the viliii bdiii the front of the c<:!l nud th« ornxMite n-vin th« back, tlit- dlU 
Ht the bnck move n tritlt- bcf^irc thiM« at toe front. e» (lint ihv movement 
runt) over the cell in tlii; dircctiun of the ixioveineDt itself. HimilnrlT, taking 
nay oDe cell, the ciliu of the c«lls behiixl it move slightly before. And th* 
ciltn of the L'clle in front of it slightlr iifker, ile uwn cina move. Hence, in 
tht» wny, aloD); a whole elretch of epithelium, the inoveineDt or bending of 
the cilia sweeps over ibe snrfiice in rip|)]cs or waves, very niueh as. when the 
win<t blows, siriiilnr wnves of bending sweep over a field of com or (all grtM. 
By this arraii;;emeiU the elRtacy of the moveiueiit i* secured, and a staoily 
stream of 6util carryiii;; tiurllclea is ilriven over the surface iu a uniform 
coiiiiniied ilireetion: if the eilta of separate cells, and atill more if the 
segiarate cilia of eueh cell, moved iiule))endently of the otliers, all that would 
be girudiieed would bo a leriea of niiuute " wubblM." of tu little use (or drir- 
inj; the lluid dcfiiiilL-lv onward a» the ufTorla of a boat'* crew all ruwinjic out 
of lime an for ]ini[H.-llinu[ the boat. 

Swift bending nud nliiwer i>lniij;1ilcMiiig in the form of eiliari' movement 
generally net with in the cilint<'d epUbeliinii of mammalH and. indc^], of 
vertebntteii ; bill nmong the iitverU'liruii^ vcv find other kiiidii nf movonicot, 
such ii> a irt ami fro moveineiil. c(|iially rapid in Imth din-ytionx, a i-urk-ecrtw 
movement, a Himple uiiduliitory moTement, and many others. lo each caw 
the kind of movement seems adapted to secure' a snecial t-od. Thu« even in 
the mammal while the one-sided blow of the eilin of ihe cpilhclial cells 
Bocurea S How of tlnid over the opithelhim. ihe tail of the i'i>erninlazoon, 
vhieh is prnctieally a siuffle cilium, by movinj; to nod-fro in an iindulalory 
liashioD drives ibe head of tbe speruiato/.oon onward in a straight line, like 
a boat driveu by a single oar worked at tbe steru. 

Why and exactly liow ihe cilium t>f tbe upitbebal cells beads swiftly ami 
itmifcbtens slowly, nlway* nctinj; in the same direction, is a nroblem difficult 
at proont tii aiiNweT fully. Some have thought that the body of the cell is 
conirnctile, or eonlnins coutrtictile mcchnuinmii pulling ujk»i the cilia, which 
arc thui' riiuplc pawivc pupp*'t» in the hands of ihe oellii. But there is no 
satisfnetory evidence for such n view. On tlic whole tbe evidence U in fnvvr 
of the view that the action is carried out by the cilium itaelf. ihiil the Ix-nding 
is a coDtraction of tbe cilium. and that the slraightoniDg corre.<|H>tids to the 
relaxation of a muscular Hbre. But even then (he exact maaner in wbich 
the conlraction bends nud the relaxation strnightens tbe tilnraent is not fijlly 
explained. We hnve no positive evidence that a longitudinal half, tbe iDside 
we mit>ht say. of the tilnineiit is conlructile. and the other half, the outside, 
eiaiilie, a suppoMtiou which has been made to explnin the bending and 
Stmi};htL-ning. In fact, no adeipiate explanation of the niatler has as yet 
been given, and it is really only un general grouuds we conclude that the 
action is au edeci of cuntnictility. 

In the vertebrate animal dliu an-, lu far a.« ive know, whollr independent 
of ihe lu-'rvous system, and their movement ia probably c«nsefeea. Iu aucb 
nnimnb, however, ns infusoria, hydrnxun, etc., the movements iu a ciliary 
tract may ollei) be seen to s[oj> and to gu on ugaiu, to be now fast itow alow, 
according (o the needs of the economy, and, ns it almost seems, acoonllng to 
the wilt of the creature; indeed, in some of thew: aiiimnls the ciltnry move- 
ments nre clearly under the iritliicnce of the nervous system. 

Olieervations with gnlvnnic currents, constant und iuterruptcd, have uol 
led lo any satisfactory results, and, as far iw wc know nt prcsenl. ciltnry 
action i.i moat airecli.-<l by ehan^ea of temperature and chemical media. 
Moderate heat ouickens the niovemeuts, but a rise of temperature beyond a 
certain limit {about 40' C. jn ibe case of the pharyngeal membrane of the 


from) hnamt* Injariout : colil raUnb. Very Hiluto alknliw «re fitvonibU!, 
BCW* u* iajuriou*. An csccw of earhoiiic nciJ m mn nbofim or oxvgitn 
ditsiiaUM* or arnvt* th<> movcmeiiu, nthft u-mjxinirily i>r [>crni»i>rtitly, 
toooHiig 10 tb* Icogtii of the •xponiro. Chloroform or pthor in sligl'it 
* ~~~ldmlldriMiorwq>ta(ls thttMUoD t«iii()oninl]r, in L-xcna kills inil dis- 

AwrhtHrl J/otemenb. 

tM. Tlic Khiti* blood -rorpUKl«s. m we hare aaid (_i3fi), atv sbl« of 
iboMKlvM to dkuii'e iheir form uid by repeated change* of form i« move 
(MB pUm to place. Kiich laovemcDtH of tM aubstance of the corpuselei on 
(^M RRKeboid. siucc ihey clowlj- resemble and appear to be idcDtieal fn 
wtaiTT Willi the niovemenu executed by tlie aniceba and limilar orftiinivott. 
IW DinrciucDi uf ihc eiiiloplosn] of tlie vegetable cell Means al»o to be of ilic 
■me kind. 

Tbr aiH'pba obangn ita form (and ibifta its jtlwe) by throwing out pro* 
jcrtinni of ita wbManoe, cnllei) {iM-uitopiHliu which uuiy bo blunt and abort. 
MWil hiilginga lu it vtn, or may be t«o loug and tbiii a^ to be men filammta, 
• may br '>f an inifrotedialc cniimcter. A« «« watch the outline ul' tJio 
bslnie cvtoMrv we mny *ec n [woiidopodium bi!giniiin){ by a flight bulging 
rftha oatline: the bulging incn-ntw by the tiTighlxiring pi>rhons of ihi' 
td/mn moTing iniu it, iIh- movcRK'ni iiiidcr ihc niirrorcopo reniindiii); one 
rf iba fl<nriiw of melted ghm. Af the jicoudopodium grows larger and 
Mfia the whole thickneac of the eotccurc at the spot, ibe graotike of (he 
mSmn ri«t be wen ftreamiug into il. foraiioe a core of endoaare in the 
■idilk of li>e bulging of ec(oear«. The peetidoixHlium mny continue tit 
pw largar and larger at tlie cxpenae of the r^t uf the body, nud eveutunlly 
ik wbcilp of lhi> amn-ba including ihe nucleua may, lu » were, hiivr 
fMad into the iiwudoptHliuiu: the body of the aoweba will now ncctipv 
Aa bIm* of the paeudoiioitiiini iuateod of it« old place; in other words, il 
«(llw cbMngina ita fonn hare aha ebang«d itd plane. 

Daring aU t£s>« movementa, and during all »iniiliir nmaO>oid movem«-nt*. 
iWkalk uf the oiganiam vill, a* far a* can be aNCLTtniuiil, have reinainc«l 
Mckaagnl: the ihroaingoiit a fwi'iidutiadiiiin in nnedirrction U nccnm|>anie(l 
bsmrmipondiiig rttraclion of the nody in other dircrtimw- If. a* N>me- 
liDin ha{>]rRe, the i>r^ni«ni throwa Mit nwiid>i|KHlia in varimx directions at 
ll> Hne time, tbe main boily from nhicli the perudiipotlia prnjccl is i^uced 
iidileluieaB ; from being n vplu-ricnl tump, lor instance, il b<-cnn>ca a bmnched 
CIk. The moreoent it hmiighc nltout not by incrcar« or decrease of nub- 
Mum Iwl by nere tranalocntion of particles ; a particle which at one nM>meut 
W ia one pawUon nwves into a new [xjeition. several particles thus nioriitg 
ttaird the aarae point cause a bulging at thai |N>ini, and several pariidea 
■uriof away from the same |>oinl cause a retraction at that ptint ; but no 
t*« futielea get nearer to each olher m as to occupy together Ibm spacp and 
tlai had to oandenaotton of substauee. or get furt^ tVoin each other h> a.i 
teiecupT mote apace nnd thus lead to iocreme of bulk. 

la tBu rMpact, in that there is no change uf bulk but only a shifting of 
(■Rklca in tncir relative position to each other, the snin-butd movement 
MHtbteaa muacular Mmlrairti'io; but in other reapecls the two kind* of 
■amaal seem diff)-n>ui, and the (|U«Mi«« ariaea, hare we the right to apeak 
xt (he aabounce which can oulv exeoutc niti<i-1md niovementa m beiitg eou- 

Wa naT, if we admit that contractility ia at bottom simply the power of 
4ifiaw ifie relative poailion of pnrticlte. nnd (hat niu^cnlar contraition t* n 
ifaraujze<l fTw nf contraction. In n plain muscular fibre (which we may 



tuk« ukiinpler itmti tb<^ Atrtuied muMle) the ahiftlng of nartides is special- 
ised ill the trni- ilint it tiiu iilmiiyisdeniiiM nlatioB to t&e loDg axis of liie 
fibre : when t\u- RUtv. coiitraciH » curtain number of nartiolo umiiue a nev 
nwition by moving nl riglil aiiglisi tn the King iixii> iif the fibre, and ihe fibre 
in cdtiwi^uiMRT lin'onie* vJiorler anil brotiJer. lu n wbit« blood 'Curputcle, 
UUKcbn, or other urgnuiMii fxeniting umo-boi'l miiv^mcnlii, the tliiAiiitf of tite 
particles ia not limitod to taiy axis «l' itu- bmly of tbe or^nnivm ; nl the immt 
moment one pnrLicl« or ono sot of piiriiclot inav be moving in one diroctiun. 
mill nnolher pnrl!i.'l« or nnutlier sel of particles in lUiolncr ilireclion. A 
pMudojHHliuin. fbort and brand, or long, tJiin aiid lilamcntoiis, may be ihriM 
out from any part of tlio surface of the body and in any direction ; and a 

Sreviously existing pseudopoiliiim may be sborLeiied. or be wholly dram 
Bck into tbe siibsLance of the body. 

In tlie plain nmscle fibre tbe fact that tbe shifting is speeialixed in rolation 
to the long axis of tbe fibre, KMCemUtes that in a conlrsctioD tbe shortening, 
due to tbe particles moving at right angles to the long axis of the fibre, 
should be followed by wbal we have called relaxation due to the particles 
moving back to take up a {tositiuii in tbe long axis ; and we have several 
timet) insisted on relaxaiion being an eosential part of tbe total aci of con- 
Iraction. If no sucb moveuient In tbu direction of relaxation took place, 
tbe fibre would by rejwuted cnntracllona be tlatleiied out into a broad, thin 
film al right angles to Its ongtiml long nxb, and would ihuti become u»el««. 
A spherical while bloiHl-curpiiicle luay, by rv|>eaied contract ions, r. e., aimeboid 
niovemeuta, tmiiHlorm Itself into such a broad thin lilm; btit in such a euo- 
dition il i» not useluo. It niuy remain in that cmidition for mime lime, ami 
by further eontracliuiia, /. i-., am<oboid mnvcTnenta, may awiuDie otlMir shapes 
or reviu't to the »])liericid form. 

So long nji we nnrrow our iileu of conlrai'tilitv to wlml we Me in a muKCular 
tibre, and understand by contraction a movement of particles in relation lo 
a delinite axis, necessarily followed by a reversal of the movement in tbe 
form of relaxation, we shall lind a diliiciiliy in speaking of the euljslance of 
the amixba or of the white blood 'Corpuscle as being coiilnictile. If. however, 
we conceive of contractility as being essentially tbe power of sbiftius tJie 
position of particles in any direction, without change of bulk (tbe shifting 
being due to inirinsio moleculiir cbange^ abuui which we know little aare 
that chemical decompowtions are concerned in the inatler), we may speak of 
the substance of tbe oniceba and while blood -corpuscle as being contructile, 
and of muscular contracdoti uh being a sjiecialized kind of eonlractiou. 

llie protoplasm of the amoeba or of u uhile corj>usole is, as we bare Mud, 
of a contialency which we for want of l>etier tenuit call iiemi-solid or mu^ 
tinid. Consequently when no tnteniat cbunges are prompting its ]ianicl«t Co 
more to this or that direction, the influeiiiex iif the surrounding will tend tO 
give the body, ii» ihey will nthi-r fluid nr M-mi-ftuld drops, a apherirnl form. 
Hence the naturitl form of the nhitt* ccrpiiMcIc iti mure or leas spherii'al. If, 
under the influence of K>me stimuhm inte.riml or exlenud, some oT the 
particles are stirred to »bifl their place, emieboid mnvenieiits follow, and the 
■pherical form is lo«t. If. however, all the oitrticlus wero stirred lo move 
wtlb equal energy, they would oeutralin^ cacti other's action, no protmnoa 
or rctractioD would take place at any point of the surliico, and tbe body 
would remain a sphere. Honco in extreme stimulation, in what in the 
OKHcle corrffiponils to complete tetanus, the form of the body is the same as 
Id rvst ; and the tctaiiiied sphere would not be apnreciably smaller than tbe 
sphere at rest, lor that would imply change of oiilk, but this as we have 
teen does not lako place. This result shows strikingly the diflerence between 
the mneral contractility of tbe a]u<eba, and the sjiecial contractility of the 



tM. Ik ibc prcrexliug rhii{itfr wo have denll witli tb«! pro|>«riieei>rii«rTe« 
pitf lo niHCK». ih*- ii«r\-c* wliich we citllott motor, ami linvc iiicidGUtally 
HUiHl of Othif nen-f* which wr ciilli-d rrnmry. liulb tfa^ic kinds of tieri-ce 
vtoowiMtttl witli (l)i- brnii) iind »|>iiinl curd, ami fonii pnrt of the general 
■fmoj ajvtrDi. Wv nhall hnvp to study hcrciiftcr in d<;iail the hrtiin and 
4iuJ ctiro ; IniI tlir ncrvuits »_V(U'm inlervcncs ei> ropenlcHlly in the procpt«efi 
dfriid out hy other Umum thut it will he deeirnkte, before |)roce«diu|; 
faltkcr, tu diM-tiM tOBM of it« mora general features. 

Tht oervmu ayfrteni iv)iMiBlB(l) of the brnin and ^irnil cord [Via. 44] form* 
i^loprtlier Ibe erreiiron/'imtl Oirit nr erntml iiemiu lyt'ein, (2) of the iMrivv 
fwlKf f^ih lliikL axis to nearly alt jtarla of ihv bodv, thwe which are 
«H«AmI with the Hfiiiial c-anl h«iD^ culled tfiiu-il and tliowt Hhich are cuu- 
with the brain, tiiihlo tl»e eraniuni, being called emniW, and (3> of 
ftta distributed along the nerves in varioua paria of the body, 
bf tpitial cord obviouHly oonalsis of a number of veii^nieiila or nietamerca, 
ving tu niorewiiiai aloog its usis, each metaraere giving off on cai^ aid* 
■ [air nt Bi>iiuil uervcH ; and a Hiniilur divi.-iun into nurtaiuo-rfti may lit- trnocd 
klhe hraiu, though \em di^linRtly, linci^ iIm: cranial uervv* tirv arrungtd in 
amatr ■omcwhM dJfiiBrail frvm ihiil uf tho spinul ucrvce. Wv may take ■ 
diA apinal metAin«r«, r«(>reBeiit«d diagrunimalicalty in Fig. 45, as illus- 
tnnu ihc general features of Um n«rToiU system ; and since the half on 
<w aw of ilie median line reeetnblee the half on the other ude we may deal 
«ilh oae lateral half only. 

EMxh spinal nerve arises by two roots. The metamere of the oeotral ner- 
IW tytUm i.' consists, as we slioll hereafter see, of ^ray matter Or in the 
iHmur and whit« matter M' on the outside. Fmm the anterior part 
tf (ny matter is given off the anterior nerve root A and from the posterior 
luo posterior iK-rve root P. The Utter naaaea into a spelling or ^an- 
0, " the ganglion of the |MiMerior root, ' or more shortly " Uie uniial 
"; the anterior rout di>e> not pit-w into thi» nuigliou. Ueyona the 
.^ _.j tfat roots join 11 form the ui^rvt' trunk .V. Wc ihall later un giro 
isvidtoc* thiil Utv nerve lihrra ci)m|H>tting ihc pcaitcrior riHit /'are. a» ikt 
kvc know at pri-M'nt. exdntivcly ciccupinl in currying ncrvoiui im)>uhNa 
fiaa ll>v tiMuts of llw iHHiy to the central uerromi fy>t<-ni, and thai the f\hm 
•Vpodng tl>c anterior rwA A arr similarly occupied in carrying impulwcs 
fca thr n-nlral nerrous system to the several tissues: lluit in to say, the 
iwaer ia ninde up of ssiuory fibres, or, i since the imnuhvs |wwing along 
Aon m the ceolral systom may give rise to effects otlier tlian iwnMitions) 
tfittmi Abree, while the Utter ia made up of tiiotor, or (.since the impulsiw 
fnisf along them from the central nervous system may produoe eflocts 
■ than movements), (ffemit 6br«s. Tlie nerve trunk N is oonsciitcntly 
pnl nerve oorapoaed of aSerent and efferent fibre;^ 
I far the greater |Murt of this mixed nerve, dividing into various brnuchet, 
»dNirifaated i .V) to the skin nud the skeletal luiiAcles, some of the librtt 
'■nier) ending in muscular tibres (JIf ). others (iteiiaory) ending in cpithrlial 
■*IU($) mnitected with the ukin, which we shall oanaMer hereailer under 

[VW. M.— l^KH fKttnn OR Ham or mc CiixknHi;ii '>i> Cmu»ki.i.i,-)i, unit «r twk l^w* 
Vjimui «l^ «iori.L» obiahuat*. *v«) tu« Asntuon Bir»rjict or tue t-rixii Cnu-. to Siio* 
Tia UoDK iw Omii>iii or tiik Siixti, NcKris frov iiir. srtmi. i'okb. tsn the ciukiii. Xrrt 
rMW mil RixKoirTili; DntiW, n, .i; nrrbnil Iit'iiiliphnn ; A, rlHht halfof cpnhrll'un: n.m^lallii 
tXAtntlfm: atomhli li> trniiirrnciibllc mam. Ihc poni VanilU ; r. r*. (he uplnikt ounl. (Iiuvliigii* 
cnrloal ini) IdnitxT vnlBtitiuiiiUi, knd ll*i>jliiU'd MniJtMtiuiu ; «. (lip lauditniulnii, fdnntil ligr (ha 
«ltiiilist«l nvuof Ihu limbuuid mtnl oamii 1 loa. lb* Kvnrnl cniilnl ncrvn . artiln^ from tbe 
hue tl Uic bnilii xnil the ulilc* of lh« niedull* oblFini^u. Bulou itioc. on cACb «l<k. arc Ibc roau 
er Urifin* oT iHi; ^v^n^l ni*nrcv, vTn k'Rl. 'IrTwl LuieiTeit. wa'l Mi^t^l In «nn^ ot IbOHv lliv <lntihl« 
icM «i> be iBtn, >nil (Iw nvllliiR nr eiidhIIkii on tlii> poalr-rlmr mn. n, «, ine ■1III1I17 or bnohtel 
Ilium. Ibtnipd bji the ftnii luuvt ivtvicnl and Dm ilonoJ iiilaiil nerroi ; L Ihc liunlaT |ilai** : ^ itw 
Mwml ptcxtH. (ImnM br (hiUut lumbar nrrv* ami llnl fmir lari^ hutyot : I, ■hiiuta idtrVoTlb* 
•IwiUiar ih« cord oat ap««i,UHl Willi UBfMtloo or tht tiBftincnisin ilflnUralai-iiD wlil«U fuiiwm 


tk^iMnwofrnworycpilfarliml cvlU. whiknihcm, .V, alter iltviding into minul« 
UmiAm Attd Armiag tilexuMV ri><), in unys aot jrct detiniUily <)ct«rriiiDe<l, 
to IMIM> ■■ccitled witb Ibr skin mtul >kv!piii) miiMln. &[orp)iol(ig»t« ili*- 
tingviili tbo pBfts which ^ to tunn the skin, skclctiil mutclra, <-tc., n» nturi'ifu, 
fno lite W&iimAniV |iim» which pi to form the vitcvra. Wr mny, nccurd- 
h^j. atll Utia nuiin pan of thi- spinnl n«rve the toauUie division <if the 

Sw* <lA«r ih? miscd n«rve .V leaves tiie spinnl canal it gWee nff n small 
InaA r, which under ihe name of (white) ramtu mnimHuiVvjiiJ'. joins one 
(f B longiludinal series of yiiny/iVi t^i cunsiiicuitus in the tboms lu the inaio 
tmfilktiie chain. This Uranch is iltstiiied to supply the viscera, and raij;bt, 
iliRftK be called tite »pt<tnek»ie divisiDii of the spinal nerve. We may say 
M ton, witbout eotering into dvtails, that the whole of the eytnpathetJo 
mliB, with its gannlia plucujwo, aiid nvrvee, ut to be rej^rded as a develop- 
MM or vipAiuion of the vi«c«ral or splauchnte diviaioi» of certain spinal 
Btms. By Di«uiM of thi« sv*t«ni splaachnic fibm from the central rwrvoua 
tnCm «n distributed tu tbe tuaucs of tb« viw^ra. *)tne of them <>ii tli«ir 
Mj pasriuc tbraagb swoudary ganglia «, and, it niny bi-. l^rtinrv gutiglia. 
IWnsj*. wesliall see, orrlain ncrVi^ or fibnwwhirh do not run 
la ikr aympnthflic syMf oi, aiwl y«-t itn> ilistribiilisl (o tbe vi.-ii-tira and an 
'iplaMDQle" in naturf'. We cnnnut, [brrvfore, iikc tb« word •yni]ialh«lio 
l*4nMI« all the Kbn> which nrv sphinchnic in nature. On the othiT hand, 
lla~i|)4anoliiii<- iM.-r%'«i"of tli« anatomist form n part only of tfauoidanchnic 
ifMn in ibv idiovo mow, ihc t^rm thus used is limiic'l to partiruhtr nvrres 
« Ibtiplanchnio mteiii distrihutcil to the nlHlonteii : and (he double use of 
tkiffin splanchnic might lead to confusion. The dilfiuullv may, ]iorhn(«, 
bntidea by call in^ the splanchnic nerrca of the anatomist " abdominal 
^IsodiBte." The majority of these splancbnic libra seem to be efferent in 
nsuir. i^arrii-inf; tmpiilaeb front lbs central nerroufl system to the tissues, 
aaMcitdin]; in plain muscular fibrw(mr others in other ways (x); but some 
rflhaSbres are nllereni and ciinvey impul»«« from tbe viscera to the central 
■VTHs iyst«U), and it it probable thai sotne ofiheae begin or end in epitbe- 
U ndU of tltc visoem it). 

V« shall have occnsi'Xi in tli« nest chapter to speak uf nerves which 
pWB ibe bI'VHiveasels of tli4' Wly, the aCHMlled va»omi>tor iicrvm. A eor- 
(i^diai iif th«4', namely, ibe Ktw-MHS(rMitor ncrvtv or fibre* are branches 
<f ibesplanchniiT division* oflho cvrebm Kpinnl nerren, aiul.iia we shall see, 
At Taii>.OOQStri('tor nervm nf |h<' «ikel<Hnl muscles, okin, aod Other part* nip- 
"""' bgrWBUitic nervw, after nmuingfor winn- distnncw in the splnndinic 
'm ( I'), turn uide (r. r and r. m) and join the eomatic division, tbe 
I qf which tlu-v necompanvnn their way to the Usfuea whose bloodvoosels 

iiO*«y »Mr- ■ 

SSMS J. ■innnvrMfKUtii'ilicnnthihrcnrd, iDihow Um fffniiorihspareKBBasrbNBK la 

t»mi0rttti otiUr ■atuBiKT /r.«(iDii»airikiiicp&n>.Biul>i»iiwnwnitaaneo(ihs<asl:Bad 
ftUMtr 'iiir n«uuf « [«lre< t[4iial nccrw jprlaftng Ihon utiMn [ 

fHC ' mi Nimvtxir * ■D-nnnornn (Mhal Vuaa, ifttmj, irwhliQiiwiMr 

'qftal camt J tiiuno*. /'faialarlamnl tiRBnaniHi oa ilut poiwnar n»l. .V « bolt tiem, V 
*B*l mm* fTCfM, «>4loalii W (krlttsl ui aiuuiUc iuukIv, .VuiiuUcMiiiKiry tail o lurltuie, Xln 
^t^V*- r tli w d arm mhlM ami Runnuinlcknii janliis UiasmiiBlton of lh« tnotaUiaae 
•IMl,*arf poaam so •* I" Id •Uffil]' Uir inoreriliUat pkOtUi'D 9. Urm ■■ F'lo Um ptrtptMnl 
pai>a V wHt mill* in n itlsathnic iuumIcl f irtawtiiilc wauy tnU or nrlboc, < oUior pcwtbls 
FS^aSi from 1 !• flTm nA Ihr (nrbfiu nm« r r <i[n)r luiiut iiiwiiiialiaBil wtilfib 
I toctaanl inHiiKl tlMtplniil ninl.ii4>] pinlyniiHHi. ■>. in otmnetdon with tM«|4nal 
\.mtaj/t*j (■aiin>ilw<otiaMnclu(>atraii>ilie midcI« (•■'ja^bUadTtaalt In oauln |iu1i^ toi 
.talS* ll«li>. :b.ta««rnir*l*Mili.-(taln anlilnc ihii fUcUa a( >b« SSrlM 1 Thn linnl- 
• ((IksetksrnMtOTMUas nnn> i.* c' an not sbovB, 



We Imvv iMwii (§ 6H) thai a uerve ),">■>■)! 1" » 'ouvcle b cotDpoacd ofneiTe- 
fihrei, chietl}' m«diillated, snmc, liowever. Iieinj: non-iii6cliillaM(], bMiai) 
toj^tber hf cnunei-iive tiaaiie. The same deecriplion faolds vooti tor llie 
whale Boiuatic divlsioti >if eacti of tbe sjunal nerves. The «piancDi)ic <livisioii 
also consists of luedulliileil and noti-medullaieil libren Unuml lojtelbcr by ma- 
nectivc tiaoufr, bul in it tbe noa-Rie<Iu Hated Rbra^ pre|>onderate, Mime bmncbe* 
a|i|ienriflg to oontaiii banllv auy tuedullaied fibres at all. Tbe ouu nie>lul- 
laled Hbrea which are found in the soniatie divisioo appear lo bo tibn-K wbich 
have joiuf d that diviHitin fmiii thct splaDcbme divUiou. Su pfimiiKiit arr 
iioii-niedtiMiiled filire* in nplanchiiic nerve* ami lieiice in the Nvnipubetic 
Nyalem that tbi-v nrt; »iiniiirinift> called 9yni|iutbetic tlbru. 

W« hn\f. Mild tbuL ibi* axiii cylinder, whether (if a medulla led or dod- 
medullaied fibre, in to )»• ci>iK-<itlvred ii» a lung drawn-odt pnM.'CNi uf ■ neire 
i-oll. Nerve crIU are liiiind in thn^ Diain *ittiation». 1. In the i^-nlral dot- 
volt* «yi>toni, tbn brain, anil Kpiiml curd. 'J. In the wvcral ganglin placed 
along the counN- of the ncrvcti, both the spinal {pmglia, and the ganglia of 
ihosnlfliichiiic oraymptitliriir "y^ti-ni. 'i. At the Icnninntionii nf nrr\'» in 
certain tiffiun. .Snme of tbcMir bitter nrcr lo hv- rvgardcd a» ^ninll, more or 
IcH terminal, eonglia, and similar minute ^uglia coDiti»ling uf Ino or three 
cells only arc found i'rciiucntly aloo^ the ci>ur»? of x planciinic norvca and 
occasionally along the coureo of spinal nvr^'es; Mich celU really, tbereforo, 
bcloDg to the wcnnd grnup. Rut be»id«» tbi«, in rertuio vitnaliona. as ibr 
inelance in certain »rgnn« of the skin, and in the organ* of special eeoee. 
nerves, j^nerally allercnt or sensory in nature, either actually end in, or at 
tbeir termination ar« connected with, cells which appear lo bo of a nerroua 
nature; such cells form a distinct calei^ory by themselves. 

Uence nlaun its whole course a nen-e consists esclnsively of nerve fibna 
(and the ooniicctive liMue lupporling them}, except in tbe central nerrout 
syiten from which it vprJngn m tbe ganglia, great ajul amall, through wlucfa 
il puttt, or which an; alta<'bi-d lo il at one part or another of ita oouiw, io 
boib of which sitoiUinns nerve crll» are found, and at ita terniiuatioii wbcn- 
ib fibres niav cod in nerve celli>. 

Jjlipniiiiiiii 1 1 niiiiii I Till MiDiii.Knr i(;ji>iiiiui(OMiii: fivni-ioR ItKiT nr 0»K or ni« 

a, tum* Mot fntvniig thv a>ngtloii ^ i, libra lisilnu llie NUDitUon lojoln Ibtnoiud ((tnal Ddrrv, 
<HH<i»»r<lrn llimrii ir»i f ihi- (snctloii ; •(. |inni.i1|«l i|nnip,if nrrvDCVlli, wttti 6bim fi^in ikua 
ft«B *iiKiii|pi III" mIK jirobiility tu iinli« Ihv loitutiii'IIn*nr roiiiMnR (irrrc ninM br T-^hapt^ 

Tlie features of these nerve cells diHer in these several siluations. T)>e 
eharacters of the terminal cell» wbii-h, an we have »«id, are chicDy evaaory. 



idI ibr Mmctiir« of (he bniin nml npiiml eon], w<> •hall sludr in detail Inter 
!«. W« nwy hero ronlinv <Hir lUtemioii to ihr norvo »IU of the }rnii<jlii> 
■■I ti Minitt of tho bninil fi'Uiiri.ii <>f llic ncrv<7 colU of the epinnl cx>ni. 

)tT. Sftiitiil ijaHi/lia. Whcn ■ longiliiilinal skIJod of ii »|>innl gaii^'lioii 
Iltuaiit»-i) uniivr n l»w iM)w«r, tl»c libra nf lh« {lostorior root ns llicy tint«r 
tkpn^lion «rc ohm-rvnl ta sprond out and {inn batween r«lativvly \aTgK 
nl nHMpi<^uiiti>>ty titiuknlcd c«ll>, which an- to a large extent arrnuKifl iit 
piM>. «oiii«nliBl nll4T (he fnaliioa of a bunrb nf grapes. [Fijt. 4<> j These 
wt tW flcrTf cisIIb; tUry h«v« frv^giiputly ■ diameter of abuiic IIM)^, I>ut 
MT bt fiill lafK^r or may be much ininlkr. In a inuuvvrse ■evltiut it will 
WvlMTntil that A lnri;i' compact maas of ihne lvIIs liea on the outer ride of 
AfgUflion, nii>) that the raoeiDoec ^roupa on the iiiiter ride ar« smaller. A 
'ly of (woiwctive tinae ratrryiiiR bloodreaseb and lympbntic* run* 
Uie pntipa, UiA paauDs iiit<i each K/oup runa beinevn the oclln and 
and a thick wrapping oTeooiWctiva tuaue cmtiuutMU with tlie sbcmtta 
lb« u«rve fcurrvutidi iiiid fornu a aheath for the wboli? piiiBlion. 
Each i>f the nerve celk — (.-nDxliouic celk, aa they arc culled — «xainin<Kl 
r a hi|;h«r jHiwer, ei(J>er after having been laolatecl or in an ttde(|Uat«ly 
■ad nepsrad aectioD, will presetii tbo fullovring fieatuna : 
eell ooniMtSof a kH hudtf nbich is, normally, poorahniH-d (Fig. I7], 
a bfMul end iu which U ]ilucci] tlic nucleu*. and a narrow «>nd whiCB 
out itiKi a (udk, and is eventually cuu- 
lined oii a* a nrrve libre. The xiibHtaoee of 
Af cdl hotly in of Ibc kiwi uhicb we call 
MygnuiaUr protoplum; Mmirtimea there 
> w ap^raniw of fibrillatiun. the fibrillA 

niii varioUB riirocliotu in the body of 
I and beiitg gathered together in a 
kapladitwl dirvction in the stalk. Some- 
tioM iIm! cell body immediately aro4ind the 
Mcltu* api>ears of a different i^'rain fntm that 
MUtr tlHt stalk, and n<>t untrequently oenr 
At gueleOB !■ an a|tK"'Ki't*^i> cf discrete pig- 
Mat yranules imbedded la tJie protoplasm. 

tW ntitJevi. like the nuclei of nearly all 
■mealli.ia brKcand contpicuous, and when 
ittoomal eumliiioa is remarkably clear and 
nAirtirr', though it appears to consist like 
<(Wr BDclei uf a nuclear membrane aii<l nei- 
^rt and Dudcar jntervtiliul material. Kven 
am nnupiciiotis, perliapa, is a very large 
H>rriml. liigbly n'fnictive nveifoliu: occaaioaally more than one atieleoliu 

i^miODdiitg tk» ocU body is a dtttinct tUfnlh or eit/tnik oontiatin^ of a 
■nKaurnt. hyaline, or faintly fibrillatcd nwnibnine, lined on (be Inude by 
ia» Miferar by two layers ot flat, |Milygunnl, niiclmK^l epitMioid cella or 
Mub; that is to aay, ctlla whieh rriNiniliU' e|>ith<;lium i-eli>, bnt differ not 
•aljia being cilrem«ly llnlieocH. buialsoin the evil IhkIv Uiini; Iranoformed 
h* untinarr graiHilar protoplasm into n anav tntmparetil dilferciitiiited 
WWrial. In ataim.ll ii|>e<-imen8 the niielei of tlti-sc plnt>-e are very cmopicu- 
<aa Undtr normal condition:! this •hciith i^ in chwe (.-ontaet with the wlinle 
Wj of the cell, but in harth'nixl nnd prvparod specimens the ivll body is 
•wrtmia iM'U shrunk awiiy from the 'heath, leaving a apac* between them. 
OHHiaaally till' cell liody while remaining at(a<-hed to ttlfllbeatb at three or 
tmot mora potuta is reiraeted elsewhere, and accordingly assumes a more 

•rtsiimist or * PvaiTOioi oakhiJ' 

(ixn: Kkkvs Ctu, 
A,u«(inlln(UB«le: B.soMnUac 


or lev Uellate form : but ihU aitiBcml ooudilion must not be oonfouixled 
with the Datuml branched fi>riu which, as we tliali aee, other kinds of nerve 
oell* iMwewL 

Wnen > section is made through a hardened ganglion, tlie plane of the 
MCtion psMiffi ihroiifch the stallci nf few only of the ceils, ajxl that rareljr for 
nnr grcnt distance aJooj; tlie stalk, since in the oase of many of the celb the 
«t«1lc is luoro or less curved and ci>nsc>|uetilty runs nut of the plane of sec- 
tion ; but ill properly iwlatuil cell* we tun itee that in aianv eases, and we 
liavo rensoOM tu bdiovc that in all caat^ thi- stalk of the oell b, as vre liare 
nid, cnnttiiiivd on into ii ntirve fibre. As the cell body narrows ioto tlie 
ttalk scvcrul nuclei niiike tlicir npiMmiraDce, lodged on it; these nre. small 
emnulnr niictd, wholly unlike the nucleus of the cell body itM'lf, and more 
like, ihoiii'h not (|iiilij lik<', the nuclei of the neurilemma of ■ m-rve. Ther 
are probnoly of tbo «imc nature as the Inttcr; nml, indood. ii* wi- trace ihc 
luirrowiiig stalk <lowiivriir(I n fine ddiwii*- shwith. which, if jin^rnt. is at 
least not oIivIook over (h« cell body, makes ilii iipixTiirnncr, nnil n little further 
on, between this ^hcalli. which i# now deiirly n m'uritcmma, and the Ftalk of 
the cell body, which hns by this time become a cylinder of unifomi width 
and is now obviously an axis-cylinder, n larcr of medulla, very line at ti»t, 
but rapidly thickening, is established. Tlie stalk of the nerve cell thus 
becoraeb an ordinary racdnllated nerve fibre. The sheath of the cell is con* 
tintied also on to the nerve fibre, uot as was once thought ne the neurilonnna. 
but as that special sheath of connective (isei'.t< »f which we have already 
auoken (§(>!<) as Uenl6*e sheath, and which ultimntely becomes fused with 
tiie connective tissue of the nerve. 

At some variable distance from the oell l]ie nen,'e fibre bears the firat 
node, and either at this or some early sucoeedinji node the fibre divides into 
two; iM we have Mxn, diviaion of a medullated nerve 6bre alwavn takca 
place at a node. The two diviiii<,itis thiis arising run in opposite diret-'lions, 
fonning in this way a T-piccc: and whilv one division runs in one direction 
toward ihc iMWtcrior root, tin- lUlior runs in an oppnsite direction toiranl the 
nerve trunk. The nerve cell is ihtw. ns it werv, u «ide picc« Bllttclie<l to a 
fibre passing through the ganglion on its wtiy from the posterior root to the 
nerve trunk. It cannot be said that in any one f^in^lion this connection has 
been traced in the case of every nerve cell of clie ganglion ; hut thv more 
care w tHkeii, and the mora successful the preparation, the greater is the 
number of cells which may be isolnt«l with their r(«j>ective T-picces ; so 
that we may conclude that, normally, every coll of a ganglion is connoctod 
on the one £and with a fibre of the posterior root, and on the other hand 
with a fibre of the nerve trunk. We have reasons further to believe that 
every fibre of the posterior root in passing through the ganglion on its way to 
the mUed nerve trunk is thus connected with a nerve cell ; but this has heen 
caUed in ((uesttoa. In certain animal" — for instance, certain fishes — the cells 
of the spinal );anglia are not pearshaped. but oval or fusiform, and each 
narrow end ia prolouj^d into a nerve hbre, one end thus being connected 
with the puelenur root and the other with the nerve trunk. In such a traae 
the nerve cell in simply a liirtct i-n large men t of the axis-cylinder, with a 
nucleus placed in the eiiiarjcenient. The nerve cells above descrilieil are 
simihtr eolartfemcnts, also hearing nuclei, placed not directly in tlie courae 
of the axis-eylinder, but on nnc side, and connected with the axis-cylinder 
by the croM-]>ie(« of the T-i)i<-ce. Hence the ordinary ganglion cell is 
sjwken of u* being unipolar, tno»e of fishes being culle<l bipolar. [Pig. -48.] 

In examining spinal ganglia celU are sometimes found which bear no trace 
of any pructw connecting them with a nerve libro. Bucb cells are spoken 
of as npolnr. It is possible that such a cell may W a young ncl) whicli has 



k » M«> MUsir r«IK <r1ik ilNlr pfDloovulm*. (MtB Um Mltalw honi or ih« tnv iDiilM or iba 
•IMd iMl . r. tmw nil altli M* toii(i«ii«4 Wn. IhMi (In uwrionitiBl* <tf tb* ftoUl iikI auditor 
MtB In Om ■—nn aiidnniliw [uutiua of the ox ; a. cell vail; t.cell ecntdui; r, iilKinmiai il, 
■AMir. pnlsai^uo* lbrnila« iW tbwib af Ibt Dbr*: /. nam ilbrv: a, ntrrv nil rmm th» 
iriMMa »wml>«> <if ■■■ : r. laatlar fell ftnin the iplnal ronl : macnlllal UO lUuntun. 

iM. Tbegiuig)i«<irth« 'p/'inrAnir Bystcm, liko the «{>inal KftDel>>< ronaiat 
*rienre«du Uid Hbm imIwHdci) in connpctlvo tiwiit-, irbicb.liowever, m 
«(>kaWTUl<l len compftii tiatur« in lh<!iii tUitn in the Hpiial KtmsUa. As 
kr ■ the duincten of tbeir nuclei, ilie nMureof thoir cell siil>atance. and 
AtpaKSMioD of B sli«ath ur« coticenie<l. what haa been snid concemiug the 
MtTC orila of apioal ^^n^lia holds, in genernl. t[ood for those of splaiiehuie 
(iwlbi: »nd, iiMJeed. in certain Kiiuglia nf the B[ilaiichnie >v»t«tn connected 
Mo the rranial nerves the nerve cells Atipnar to be whollv like tlwwc of 
fiwU i^atiglia. In most splniu-hnic f^iin^lia, howe\'er, in t^oK which nre 
piMnliT allied lympiilhetic i^aiix'Hii, two iinjior- 
(■t dHfennca may be obM-rvod l)«lwe«D whnt 
n may call the <-tinraotcri8tic iicrv* cell of the 
^Ineknic ganj^ion and the cell of (be ipiDal 

u th« lirsi plaw. while tbt- nrrvc cell of the 
^inal gangliii hu one proocM only, the ncnrc 
fill vt th4> KplnncUnic gnn^lin may bnre, and 
^inaptly ha>, tw«, ihrre, or even fonr or tire 
it ii a muitifojar rell. [Fig. 49.] 
iIm viwfind pUoi'. while these proccBBtfl of 
•pUnchnti- ei"'?""') cell arc continued uti ns 
libraw, aa U tiu- nnglc process of the Bpinnl 
mil. ihri nerve nbrea n formed nre, iu 
of mi»t of tlic proceosea of a cell, and 
MWtinim in the case of all the ptoeMMS, Don- 
BMUillatM) librr«, nnd remain non-meditUkled as 
hr af the^ can be truced. In aunie iiiHtailMi one procMi beconwt at a little 
teanM miin (he cell a tnedollated Hhre, while the other proceaea become 
■■hOMlu Hated 6brea : and we nre led to Iwl'un'e tlm( in this case the medul- 
filtre is proceeding fo the <^ell on ii« way from llie central nen'otu 

SnujTB !lEaVE CUX, tMM 

ll^>^^nlu•l Vimlvub Oou'umi 
iir A Form or 8ii Momim, 
i»«cnllM<aLI Aftei Buu.) 



mtcm, and lluit the Don-niedultated librw are proceedini; Jrom ih« cell ' 
taeir way lo m»re [leripherally [ilaced parts ; ilie nerve cell seems lo »rve u 
II crntra for the diviniun of n«rve fibres, and also fur the cIibd]^ fVom ni«dul- 
Intcd In DDii-UMfdu Hated fibres. 

[r ci)iiiH.'i|tK'Uc-e of iU tbus poswwiug mvotaI procesMS. the splauchnic 
gnnclion <-cM !:> more or lew irre^lar and oft«D alar-like in form, in otitrMl 
ro tbr pi'iir Khu|ie nf tb« »i>iniil gangliun cell. But iu cN-rutin .situation* in 
cerUiin auimnl* — lor iiiatiintv, in (he fVu^' — iti many of lli<- );angliu nf the 
abdomm. uid in thi^ umiill nui};lia iu llie heart, puar-;*hapfM) i>pliini-hn>c 
ganglion cclli^ arc nint wilb. In mich euees the nucleated shwilh w ilintinrtlr 
ncar-tt]i&rM.'i) iirbnllodd-ihniHMl.aml thi' liir^ir c>niiH|>ini'>ii» nni'li'ii:! i* pla<»H, n« 
ID llic Bpiiifil gntigllon ftll, mar ihe hnwil i-nd. Inn ih« cell Mib«it«nc« of tbe 
cell is gathered nt thi- «tnlk, n»t into ii t>iii-_di- librc. hut into two fibres, one 
of wliidi in etrnighl and tbu olfat-r twiwU-'l K|)irally round tbe utrnigbl oae. 
T\w tiro libm run for somr di»tanw tojnitlier in the «ann! funnel -shaped pro- 
longation of the nucleated sbealh of tin; cell, hiil eventiiaiK separate, each 
fibre acf|uiring a »henth (sheath of Henle) of itn own. fienerally, if not 
always, one Hbre, usuiilly ibe straight one, becnniM a mediillated fibre, while 
the other, usually the twisted or spiral one, i* continued as a uon-medn Hated 
libre. While within the common nucleated abeath both fibres, eapedally tbe 
Hpiral one, liear nuclei of the snme cburacteras those seen iu a oorrespouding 
riiluation in the spinal ganglion cell. It hiis been uiaintatnetl that the atraighl 
mill npiral libros take orimn from diHi^rent part* of the nerve cell, but UtU 
bnn not been definitely proved. 

In the wntlla of the iniestiiie, in connection with splanchnic nerrev, are 
found [K^culiar nerve cells fumiiiig what are known as the plexuses of Meias- 
ncr and Autrbach, but ue shall postpone for llie present any dcacription of 
thrac or of other peculiar aplanchnii.- cells. 

§ 99. In the eerUral n«rvou» mjfti-nt nerve celln are fotind in the so-called 
jroji matttr only, tbuy mtf alwont from the while tnatfrr. In iho gray maUer 
of tlte spinal cord, in tbe pnrln .-iiiokon of ns the niilcrior comua, wc meet 
with remarkable nerve oclln of the following cliarucier;. Th« oelU are large, 
varying in diameter from oO^ to 140/'. nnJcach coiiai»t8 of a cell body sur- 
rcHiiiding a large conspicuous rcfraclivu nucleus, in which is placed an even 
still more conspicuous nucleolus. The nucleus resembles the nuclei of the 
ganglion cells already deHcribnl, and tJie cell body, like the cell body of tbe 
ganglioo cells, is composed of finely granular piotoplasni. oflen fibrillated, 
though generally obscurely so; frequently a yellowish-brown pigmi^ut is 
depiwitfJ in a jiart of tbe eell body not far fn>m the nucleua. Tbe cell bodr 
is prnlonged wimetimes into two or three only, but generally into several 
procewoi, which appear more dislinctly librlllat^l than the more oentral 
partM of ihi- ei.*ll bmly. These proceseeH ar« of iui> kinds. One proocia, and. 
apparently, "Ue only, hut in tJie case of tbe cells nf thi- anterior curuti, 
always one, i» prolnugud a^ a thin nnbranched band, which n<liiiiiH a fairly 
uniform dinmcle.r fur a <-i)n9iderable dlstaiioe from tht! ci^ll, and when suc- 
oessfully traced is found Hooner or later to RCjuire a nKilulln and to become 
the axis-cylinder of a ncrv-e fibre; tbe proccMce which ibii* pan out from 
the gray matter of the anterior curnu through the while mnttor form the 
anterior rools of the spinal nerve. Such a pruccM ix uccordingly called the 
run»^liiuii-r proKJif. The other pmcowft* of the cril rapidly branch, and so 
divide IdIo very delicate tilanicnts which are soon lost lo view iu tbe aub- 
•laBee of the gray nialler. Indeed, the gray matter is parlly made up of a 
plexus uf delicate tiiaments arising, on the one hand, from thedivinoD of 
procCMSS of tbe nerve cells, and on the other, from the division of ifae axis- 
vylioden of fibree running in ilie gray matter. 




TWceltt ■ Dfit HirroiiniM like the ganglii>ii cell bj^aHislinct sheath. Aa 
*r ifcall mr laur on. nhile tnatint; in detail of the ceiitnil nervous syHtem, 
kU iki nvn'oup rlcnirnw of chL< spinal cord are supported by a network or 
yy w tf rk of delivnte peculiar liaHie called ngtiroflia, aiialofptus to and 
Mm| Btuch lite nine function m Kiit diHereot in origin and nature from 
cHMlttva tiaua. TIub neurofjlia forms a ahcolh to ihe nerve cell and to 
|lt|>nBMa, M well ns to ihe nerve fibres runnin); both in the white and tbo 
piTBdilter; li en ce within the eeiilral nervous Bjelem the fibres, whether 
■MilnlUtcd ur no, po asc no Mrparate neurilemma: tubular sheaths of tlvc 
pfarofUa give the axis-cylinder and nicdullA all the suppuri they need. 

All Ike nerve celb Dftbe anierior cuniu probably poase«s lui axiii cylinder 
mem, and other e«iU similarly prnv><led ntlh an axis cylindi-r pmcnui lire 
land in oUwr parti of tbe gray matter. But in reriaiu parts, o*. for iiwtaiicc, 
btlw |RMWrior comu, many of the oella appear to poiaew no axi^rylindcr 

Cs; In aueh«Mtaall the procMtei appear to bmnch out rapiilly into lino 
nt«L Except for thi« abaenue, apparent or real, of iia axis -cylinder 
fraoaa, Mch cwlls rOMUiblu in iheir iceneml liBatumt the celU of tbo ontsrior 
(■nUithoagli thay aro getwmllv somenhai smaller. Sjitqikiug gvoarslly 
ikmat feature of the ner^'e ccfhi of the central nervmiK «y*teni nf distia- 
fined from the ganglion cells is the remarkable nay in which (heir pro- 
MMsbmneb nlT into a number of delicate lilamcnta, oorr(»|innding to th« 
dsDtala tlainenla or (ibnllir in which at lU termination in (he ticeuee the 
tiit-crliiuler fd' ■ werw oftvn ends. 

i idO. PmcD tbe alxive dcecri|itioti« it ia obvious that in the spinal cNird 
maUdl ai repnwnling (he (vnlnd ncrroiin syMem we may at proiieint cou- 
iM oataslfM, iMviug the brain tor later study) aSeront tibrw < hbres of the 
pauior root) an io some way by meona of the gray mailer brought into 
OMictian with efi^rent 6bres (iibrca of the anterior rnut j ; in other word*. 
iklMfaMi oord ia a ctoiire unitini; afl^rent and eOtrent fibrvn. The npitial 
pOfM am tkot centres in thi? tteiine ; the nerve cellti oompiMiiiig tin.' ganglia 
maaiply rvlnys on ih« aStnnt fdirc* uf tho pouvriur root, they have no 
(MdMjad whatever with i-tTvrcnt flbroa, ibey are conn«-ml uitti lihr«» of 
a* kind only. Conoeroing the ganglia of the Hplaiiehnic Kynteni we eaniiot 
bill cwMa make at present a p<Htitiri; stalument, but the evidpn<-e to fur at 
MrdkpoHl pointa to the ooncluntnn that iu tJiem as in the ipinal ganglia 
vdl aerve call belongs to fibre* of »im' function only, that whore several pro- 
lof a cell an^ prolonged into nerve fibr«, thi«« fibr«« have all the MIID« 
>, tbe nerro cell being, lu in the apinnl ganglia, a mere relay. We 
I ■Wiihitofy evidence thnl in a gnnglinn the fibres snringing from or 
id wilb one cell join nnolhiT cell so n* to convert the ganglion into 
joining tugulber cells, wbuae nerve fibres have dilfcrent liiiictions. 
r shall ban* later flo to bring forward evidence that tbe nucleated cell 
\»ij iif a nerve ell in a ganglion or e)»«wbcre i» in some way or other con* 
td with iIm- outrilion. the growth and repair of the nerve Hbres umnsing 
I it. Bcaidm thir nutritive function the multipularcellnof tbesplaaiailiio 
ipprar to serve the purpose ■ if multiplying the tracts along which 
B« impulses may nassL An impulse, for instouce. reaching a multip'ilnr 
I line of the proxiuiul (■ympalhelic ganglia along one Dhre or pmoen 
tre in very many casea being a medullated &br«) <«n pOM out of the 
■D various directions akxig several proeeasea or fibr«a, which, in tbe 
ity of CMMs, if not alw«ya,are non-mcdu Noted llbrta. Thux theM' nerve 
lOrgansof distnlnitiou for iinpubes of the wime kind. Wlnu further 
liana of the imniiLM« thtu imsalng tlirough tliem ibeae ganglia may 
t about we do not kn«n-. 
I only in aome few iittiaiicea that vre have any indications, and tliose of 


vittidratrn froni the stiinuluH, or tlir movenieDt U colcuUml Ki push ur wipe 
Bff ay the auuulus. In other words, a cenain pitrpme is evident In Ike refflei 
act km. 

Thus in all cases, exc«pt perhara the very wmpleM, ifae rmiremenu aall«l 
fivrl)) by a rv&vx action are exceeoipgly coniplt-x cutiiiiarvH nith t\>a» which 
result IKiii) tli« direct iititimlation of a motor trunk. Wheit tho piTtphcnl 
Htmup of a divided Miativ nerve b siiiniilnted with the iaterruptcd nurmit. 
the mosclcit of the )e)i are at i)n<-e thrown into tetanus, cviiitinue in the fawt 
rigid iiinilitiim diiriD)^ the )NiitM|;e uf the current, nnd nrlii\ inimii|iiit4!Jy on 
the mrr(-nt l)rii)){ nhiit otf. Wlw-.n (he «amc cunejit U iipiilicd for n iieociiKl 
onlj, tu the i>kin nf the llnnk ofit hraiidcw hn^, iho 1«|; io dntwn u|i und tbt 
fixit nijiidly ■wept over the fpot irrilitlei), in if to vii\>r nwny ihe irritnlinsi 
hilt ihi« movirmr'nt \r a complex one. rt«|iiiring tho (iinirmction of imrticulic 
miiKltti in a dcRniir BniuiTiio:, with a ciirvfuIlT Adjtiitod pmportitHi iMtweca 
Ihe aniuiinlH of mnlriiciinn of the individuiiC nm»rlce. And this complax 
movemenl. lhii> tialanc^l niid arranged i>cric» of contractions, innr be reneal«il 
more than once as the result of a sin);le filinuilation of llw «kin. W hen S 
deep breath ii caiwed by a dash of cxild water, the same eoordiiiaUNl aad 
carefully iirrnnged aeries of eoutradions it also seen to result, as part nf a 
reHex action, from a simple stinuilue. Aud toany more examples mjglii h« 

In such esMs as these, the complexity may he iD part due to the fact that 
thesitmuluB u applied (o terminal sensory organs oud not directly to a nerve- 
trunk, As we ijJiall see in speaking; of the senses, the impulstu which sie 
geaeralad bv the application of a stimulus to a sensory orsau are more ooia- 
pl«X than tJiose which result from the direct stiinulntion of a seiwory uerve- 
trunk. Keverliieleu. r«flex actionti of ^i«at if not of e<(uwl complexity twf 
be induced by stiniuti apj>1i<^d <lirvctly u> a nerve-trunk. We art-. t)i«rcAnk 
oblijtcd to conclude that in a reflex action, the proc<*»e» which are originnKd 
in tite <vntn- hy the arrival of even itimplc impiilM* hIoiik afivront itvrvA 
may be highly ooinplex ; and that it t* the ^vMWtitutiiui nnd condition of tbf 
cmtre which determine)* the complexity and character of the movemMlU 
which are cfliNted. In other uorils, a contn> concerned in ii rvllex action it 
to lie regarded m oonsiitutiuK a sort of molvcular machinery, the charadtr 
of tho rcaulttng movementa being dotorminei) by iIh- nature of the machinery 
Ml going and its condition at the time being, the chnntder nnd antount w 
tho aflerent impiilseM deterniiiiing exactly what jinrta of and how far lb* 
central machinery is thrown into action, 

Throughout Ihe above we have purposely us«d the word centre, avoiiliof 
tlw mention of uerve cells. Hut iiuaoubiedly the pari of the spinal eora 
AVting OS centm of reHex action is situated in tlte uray matter, which gray 
matter is chamcterixed by the presence of uer^'e cella ; undouhiedly also [lie 
etlerent fibres are coniiecied with the afTereni libres by means of cells, cer- 
tainly by the eelle uf the anterior oomu described in $ !>!* aii<) pruhuhly also 
by other cellf< in tho na8terii>r curnu or elsewhere. Hn that ii n-tlex nition t* 
carried on undoubteoly tfirouffh cdls,. Hut it docs not follow that a cvllular 
mechaiiisui is eeseiitial in the sense at nil eveiitji tiiat the unelei of the evils 
have anything to do with the matter, or even that ibe most iniporinnt of the 
mnleviilar processes <H)iistiinting Um change* taking places in n cenin- during 
n rellex iicliim an- cjirn^'d mit onir hy the cell suliftanc*' imuuxiialclv sar- 
roiiiKliiig iht! nuclei. The jiowcr of carrying out a reflex action in proluibly 
contingent on tli« natun- nnd arrangement of a xis-cyi indent, a»>l of the 
branching mstrrinl hy which in a nerve centre tho alfetvnt and efferent nxi»- 
cylinder* arc joioeil togi-ther, the nuclei intervening only so far as they have 
to do with tho growth and repair of the nervous material. 



Mirmil impalws, nisy mil forth it cuiivuImvo liluf cuuf;hing,in which n verj 
Ivyi auinbvr or niutcln xrc thrown into rioletil contrftcliuna; vberMB lIh- 
not tiiBtirl of (he hnir wiih oilier eurliiccn of the hotly mny produce no 
(ktltra cflisct at atl. Similarly, whilo in the brainlcfe but otherwise iiarmal 
ftvfti ■light touch lU) the skui of the Hnnk will produce uolhin^ but a fuint 
titt of the underlvin^ muitcl^ tiie Bame touch on the same part of a frog 
ptMMl will) slfychiiiue will produre violent tasting teianic contntclions of 
MVlt di the mutctee of the body. Motor inipulses. at ire have bc«d, travel 
tbof OMlor nnrreit «ttliout any ^ttM. expenditure of eoergy. and probably 
widmt IncreaMiiK lluil espeudJItiru » tbey proeii-^d ; and [W same is ai>pa- 
nHlT iW CTur with allvreiil impulH» paunne alonj; aft'en-ni n«rv«). Wheti, 
hw V rr, in u n:f)i-x mti'iii alli^reiil impulses reach the nerve oeuira, a cliSDjte 
fallwMtDrv Btul uw)^iitiid« of the iiupulM« lak«s pinoo. It is uot that in 
iWMrr« ectiin.- Ihe alfi>rvut impulse* sn simply turned aside »r reflected 
bill riltcvnt impuliMX: aud hence the name " rellcx " uctinn is a bod one. 
It n rather that lh« nllStreni impnitea ad afreah, at it wen.-, tu a Mimulua to 
Ibanrv contiv, producing nccnrding to circnmstancea and cvHidiiions cither 
■ Ira >cak vflintvnl inipulMa oraintiltituileof utrong one*. Thv nerve rcnire 
Btt W rvgardeil m a callcoiion of c xpluaive chargi« ready to be dUcbnrged 
■il M> lo atari oHervtit impulmy along cvitain vtlm-nt ncrvcv, and thote 
ikmtarvaoarraUMd rim) w rcJatnl ^l crtntn ttfli-rcnt uerris, that alli;reiit 
isjalHa loichinr ua ocntre along thom ii(Tvn:> may in one t'iuw dwchnrge a 
Iff anljr of the cnargot, and so give rim to fwhle movonionU. and in nnutlMr 
^ttiBlAmtffi a very large numbor, and eo give rise lo large and violent 
Mnmnta. In a reflex aolioD th«i (h« number. inlen«iiy, chnracler. nnti 
ttuflntlon of the eOerent inpuleea, and so the kind and amount of raove- 
■nt, will depend i^htefly on what takes place in the eciilre. and this will, in 
Hro, ibfwnd, on the one baud, tin ihe cunditioo uf the i^enire. and, ou ihe 
mWt.oh il*e qiectal relatiooi nf the oeulre of Ur- afTen-Jil iinpultiee. 
At tilt ttme lime we ore able Ut recognize in uiunt tuDi-x notions a certain 
between ihe Mrenglh i<f ihe utimuluH, or the niaguitudi; of the aller- 
impuhea and the extent nf the movi^mrnt or tbc magnitude of the etlVrenl 
The nerro-ocn Ire remaining in the unmv ronditiuu. the sironger 
iraan inimeroua atftrcnt impnUcs will give ri^ t» the more forcible or 
■or* KimprahrnMiTe niciviMnentH. Thu«, if a flank of a hrainlen iVog lie 
nn lightly tuuchfci, the onl^- reflex movement which is vifihle is a nligbl 
ttiidiiDg of tbo niuaclm lying inimtvliately tindnrnralh the spot of skin 
itiaaklMl. If Ihe stimulus Ik- int-rvnsc-d, ih« iDovoments will sptvwl to the 
Ukfrkg nf (lie ■aim- ojde, which fn:(|tiently will execute a niovemenl ealcu* 
hud lu puab ta wipe awny the rtimulu*. Ry forcibly pinching the santc 
^>if skin, orotkerwis'- inrrcnj>ing the stimulus, the rt^iilling movemenlp 
aai In- led to rnibran^ ihv forr-leg of the same side, then the opivwile side, 
•M Gaally. almiwt all th«- inusclee of the body. In other word*, the disturb- 
I RioiBg in Um' cvntre. confined when Ihe stimulus is slight to a small 
of ifae centre, overflows, su U> siieak. nbeii the stimulus ia increased, to 
pane of the eenirv. and thus throws impulses into a larger and larger 
tt of e&rent nerves. 
Wt laay Mid. without going more fully into the subjeet here, thai in mon 
ntrxai^oua a sjiectal reialion may be observed h«tweeu the jiart stimulale<l 
' tke resulting mureraeoi. In the simplBSt eases nf reflex action thb rela- 
ii turrely of such a kind thai the muaoJca tbrowu into action are tbwe 
I by a motor uerve which b tli« ftiDow of tbe sensory nerve, the 
latiiMt of whiHi calls forth the moveittent. In the more complex reflex 
iiiM of the brnJuleai fnig, and in other cawa, the relation is of aucfa a kind 
tbe raaulting movemeiii heai» an adufAatioit to llic stiniulua : tbe foot i» 



withdrawn rrom the slitnultu, or the 
In other wo: 



renient is ai]eulftt4!d to push or 
a c«riBin purpow is evident in the rvBez 

awftv the stimii 


Thus ill nil cnsee, eioept perhaps tlie very Mtnpleat, the inovenienu unlM 
forih hy a reBex action are exceediii);ly complex cDiupnred «iih thoM' which 
rtnilt from the direct atimulation of a motor Inink. When Ihe f)eH|>h<^raI 
B|iiui[> (if a divided sciatic nerve is sliniulaied with the inlerrupted etirreni, 
ihe itiuiiHes of the leg are at oiiee thri^vrii inln tetuuui>. continue iti ih« ^stne 
rigid Liindiii'tu (luriii); il>e puiMky:e of the current, aiid relax iinmediabely on 
the curreiil bein^ abut oS*. When the Miiuie current u applied for a aecoad 
ouly, lo the skin uf the flajilc of a bminlenii {nig. the left iiamurn up uihI the 
foot mpidly Nwrpt iivur the «pi>t irritated, tu if t» wipe away llie irritation : 
but thi* niovemi-nt \» a complex one, nyjiiiring tlie (■oiitnictiuu of jittTticular 
hiumIm in It defiiiilu *ei|ut:iiM!, with a cnrefullv udjuflcal (irojiortiou bctwcail 
the Binouiitu of contraction of the individual nnMtcloi. And thtf complex 
movement, thi* biilancnl and nrnin^i Hcrioi of coniraotiomt, mav ht rcpmitcd 
tuurv thiu) onov la tlit- rcsidl of a *inglc MimulalioD of thv slcin. W hen A 
deep bnutth i» oiu^'.d by a dni>h of coh) water, the Minie cnonlinntcd nntl 
cnrciwlly nrniiiged Hcrit* of coiilrnclioni' ij« also w«n lo nviill. n> part of a 
rcflax action, finom a simple stimulus. An<l many more oximiplM might b« 

In such cams iis thesis, the complexity may be in pari due lo the fact that 
the stimulus is applied lo terminal tvuf^rf organs mid not diric<ctly (o ii uerve- 
truuk. As we shall see in speiiking of the senMs, the impulses which are 
generated W the application of a stiiuiihis to n sensory organ are more com- 
plex than those which result from the direct stimulation of a sensory iierve- 
tnink. Nevertheless, reHex actions of great if not of equal complexity mar 
be induced by stimuli applied directly to a nerve-trunk. We are, therefore, 
obliged to conclude that in ii rutlex actioti. the |>rocucie« which are origiuaic<l 
in the reiitrn br the arrival of even simple impulua along oflitreni ncn-a> 
may Ix) highly complex ; and Ihul it i» the couMitntion nnacondition of the 
centre which determine* the complexity and chnriieter of the movements 
which are elTecied. In other nords, a Mtutre cuncerned in a rtdlcx aciion is 
to be r^nrded as constituting a sort of niulecular raachinorr. the character 
of the mulling movements liemg detr:rminc<l hr the nature of the machinery 
Mt going and its ondrtiou nt the lime being, the chariicter and amnuni of 
|]ie aRi-rent impntm-s determining exactly what |>arts of nnd hoir far the 
ccnlntl machinery is thr-iwn into iietioD. 

Throughout the above wo have purtMisely used the word centre, av')iding 
the mention of ner^'e cells. Itut um)i>nblcdlr the part of the spinal cord 
acting as centres of rcllex action is situated in the gray matter, which gray 
mailer is chanicteri/^d by the prciience of nerve cells; undoubbodlr also the 
eflerent fibre# are connected with the atleivnt libres by means of cells, eer- 
taiiily by the cells of the anterior cuniu (le«cril>e(i in !i ti!> and probably also 
by other cells in the jx'iAti-rior eornu or eiaeivhere. So that a retlex acliou b 
carried on undoubtedly Ihrougli celk Dot it docs not follow that a cellular 
m«chanism t< cwentiul in the sense at all eveuU that the nuclei of the cells 
have uiythiog to do wilJi the matter, or even that Die niosl importam of the 
tDolet'ular proceiKii conntituling the chanKca taking plai-e* in a centre during 
a rellcx action ore carnal out only by the cell Hul(siant« luimediaiclv mir- 
rounding the nuclei. The power of eiirrying out a reflex action in ]>n)liahly 
routingtmt on the nature and nrranjiement of axiii-cvlindcrt, and of the 
lininching material by which in ii nerve (centre the alVrrcnt nnd eHi-'ivnt axis- 
cylindcri are joincil Ingethcr, the nuclei inl^-rvwiiiig only so far as Ihey have 
10 do with the growth and repair of the nervous material. 


: 101. Aidamatif iKii&nM. Efforeoi iin|)ulM» froquently iiiiie frmu the 
~ I tad vpioal cnrd mi)<l su give ri«c lo mnrpmcntfl without Mag ubvioutlj: 
by ftnjr BtiinuUtiuii. Sucb louvciovnts bit *pcikfti uF na HuloitiKtiv 
auft. Th« d&fvnt ioipulMs in xucb cuws tire started bj chaDgw 
I Bwva ccnire irKich tirv tuA tbi.* immediute r«Hilt of lti« nrrivxl At tlic 
lOMUv of «llen-Dt impulse* from wiihoiiE. Hiit irliich appcitr to ariu* in 
mv* OADltx' itwlf. CliHDi^ of Ihis kind may r«i-tir rlirthmicslly : lliue, 
llhall te*, we tikve rcaMn lo thinit ttml in n cerlttin part of the mt-diilU 
. cluuiKfa of the o^rvotiB materia), recurring; rhythmically, lead to 
kythmiv dwrltarKv alone c«riaio nervM of ei&renl imputic* wherry 
I conneoted wtlli llii< cbcei nr« riiytbinically thruwn iuto soliun and it 
_ . nically r«peaioil brealhinv is brought about. And otli^r Kimilnr rhyth- 
Htaioiniilio inovt:iii«iitt< may m atrri^ti out br other parts of tli« spinal cord. 
Pnn Ibo bmiii itself a much mure varied ami npfiar^uily irrt.-|{ulur di«- 
ttgpat rtlirviil iiii])ii)»t«. net lh« obviuiia nvull of any iminvUiaivl^' for?- 
fill illtTeiii impuliMtt, and t)M-rff»ni not formiiijt part of reAex actiona, it 
WJ atintnon, miidtitiitinjt what we apcalc of as vulition, eflereui iinpulsM 
ikatuiiiib); being called voliltunni or voluntary itopuUe*. The npinal oord 
qwifRMn lite limin dow not appear aipuhl« of «zAoiiting thiM! voluntary 
BMonmi* : but to Xhm au1>J4«t w« tludl retuni when •m come to ii[ioak »f 
iWnnual aarvoiu nyvtem in detail. 

Wtmid juRt now that th«rc i* no antisfaciwy ev!i)cnoo that t)i« ganiili* of 
ibifUiichnic •nrMnm «vcr ad w (M.-ntrc8 of ra flex action. TIm eruleiio*, 
iuiriv, that tnow ganglia may Mrvc as conlra of rhythmie Mitomatlc 
■MOM at firf>t eight of »»mc stirngth. Several organs of ihd 1>odr 
sing naecular tij«ue, the most notabln being the heart, are during Vitt 
'\ IB riiytfamic autotnalic iuovenieDt«. and in niiinv cato* oonlinne thtf* 
inis aA«r renMVal frf>m the body. In nearly all titeae caaea (rau){lia 
vtpnacnt in oonnectlou with the mutu.'ulur tiMM«: and the preaeooe axul 
nMd euulitjon of th«n puiiiiia t-am nt all evenu in many ouea in tone 
«iti«ent«al to (hi- due |iprformBn(« of (he riiythmic auiontalio niovemi-nla. 
bjnd, it ha* brvn ihmitihi thai the iDovementa in rjueition are DMilly due 
biW rhythmic auiimialtc generation iu the cell* of thcai- ganglia of uiTerout 
■ifalm which paaHngdowo to (he a|>proprial« muwular fibrt* call forth 
kr ifcrtliraic movameDt. WIku wv come lo otiidy tlicao mi>vemci)t« in detail, 
Wifaall find nMoiu for coming to the conclusion that this view in not sup- 
|Mlal by luieqttMc «vi(l«ocfi ; and, indeed, though it i* perhaps immacurc to 
•iki a dogmatic ateiWMMit, alt tlw evidence goes, aa m« have alrcailyMid, 
titfew tbat i1k- great use of tlw ganglia of the snlanc!hDic ^sleu, like that 
rflbtlpiltal ganglia, is connectmTwith the nutrition of the nerves, and tbat 
Aaaanifllam do no* like the central nervous system act aa centm eitlicr 
Mt«atic or reflex. 

f 108. Inkibiliiry nenf. We have said that the fibrea of the anterior 
nNiboutd be calM eflerent rather than motor, becau» thou);h they all 
any inpiilaea outa'ard from (he central nervous aysteni l<> the tiwttw, the 
tataUa vhich they cany do nut in all casea lead to tlie eoutractton of miu- 
(w Cbrva. Some of titeae eifervtit l)br«« are distributed to j^laodular ttruo- 
>Mm, ftir instaoM U> the aalivary glanda, and impulses pusaing along these 
lad Id changea In opiibdlal eelu and their surroundings whereby, without 
uymucnlar oonlrai-tion necvMMrily inlerveniDg, xecretion u brought about; 
tkt sdioD of tboM libret of accrbiiou we shall study in coniteciion with 

BaHia (his ihert are efferent fihre)> going to muMuIar tinue or at all 
enats tu musmlar orgaiw, (he inipulM* piii<iiin>[ alung which, so far from 
Miimif almtit innN-nrnr I'ontractiun. diminisli, hinder, or Mop moveniculB 


already in proeress. Thus, if when the heart is beatin); regularly, that is 
to Miy, wheii me muscular fibres which make up the greater part of the 
heart are rhythmically contracting, the branches of the pneumogaatric nerre 
going U) the heart he. adequately stimulated, for instance with the interrupted 
current, the heart will stop beating ; and that not because the muscles of 
the heart are thrown into a continued tetanus, the rhythmic alternation of 
contraction and relaxation being replaced bv sustained coatraction, but be- 
cause contraction disappears altogether, alt the muscular fibres of the heart 
remaining for a considerable time in complete relaxation and the whole heart 
being quite flaccid. If a weaker stimulus be employed the beat may not be 
actually stopped but slowed or weakened. And, as we shall see, there aie 
many other cases where the stimulation of efferent fibres hinders, weakens, 
or altogether stops a movement already in progress. Such an effect is called 
au inhibition, and the fibres stimulation of which produces the effect aic 
called " inhibitory " fibres. 

The phenomena of inhibition are not, however, confined to sucb cases u 
the heart, where the etferent nerves are connected with muaculu- tisBue& 
Thus the activity of a secreting gland may \t^ inhibited, as for instanoe whm 
emotion stops the secretion of saliva, and the mouth becomes dry from fear. 
In this instance, however, it is probable that inhibition is brought about not 
bv inhibitory impulses passing to the gland and arresting secretion in the 
gland itf^lf, but rather by an arrest, in the central nervous system, of the 
nervous impulses which, normulty, passing down to the gland, excite it u 
we shall see to action. And, indeed, as we shall see lat«r on, there are many 
illustrations of the fact that ntferent impulses reaching a nervous oratre, 
instead of stimulating it to activity, may stop or inhibit an activity preri- 
ously going on. In fact it ti< probable, though not actually proved m every 
case, that wherever in any tisiue, cnei^y is being set free, nervous impulsn 
brought to bear on the tissue may affect the rate or amount of the energy 
set free in two different Wat's ; on the one hand, they may increase or quicken 
the setting free of energy, and on the other hand, they may slacken, ninder, 
or inhibit the ^letting free of energy. And in at all eventa a large nnmber 
of eases it is possible to produce the one effect by means of one set of nerve 
fibrcH, and the other effect hy another set of nerve fibres. We shall have 
occasion, however, to study the several instances of this double action in the 
appropriate jtluces. It is sufHcient fur us at the present to recognize that a 
nervous impulse passing along a nerve fibre need not always set free energy 
when it reaches its goal, it may hinder or stop the setting free of energy and 
is then calle<l an inhibitory- impulse. 

The blood, ns we have nid, is tlic inlenial luedimn on which the 
tiatt lire ; from it these drair their food and axvgea, Ut it tber give up ilio 
ptdmU or vme inattere which the}' Ibriu. Yhe tiaauM, with toiiic fuw 
aaif&out, MTt tntreraed l>r, and ihua the eJeraeolB of the tiaiuei Humuwled 
h, Mtvorks of mtuute lliin-wstled lubee. the ra/iiflarii bloodvetneU. Tlie 
timmiuar Mriuled tuuscle fibre, for iostaiiee. ia surnHiiideil by cnpillariM. 
nmaf in the (vnmevtive (iaaiie otileitle but iluiM; lo the aarcolemma, nrrangan 
biMKcrk with uKirt- or leM n?ctaugular nit'.ibeN. Thriu- cupillnrtm urv 
dtNd tub<« nith <NjntiniiuuK nidti, and the hhmd, nbich, nit nc xltnll ttx, u 
flMmallf Hrcamiog through tbem, a at a whole »>iili(i«d lo tJicir channela 
ml iom But cacapv fn>m theiu. The elementa of the tiwtiM lie out«iile tin 
HulkriM «od forai ettravimcular xMrit, nf iliHbmit forin nnd «iie in tliC 
diMat ti«UM. uirroiifiiU.ll hjr I'ttpillury nHworlu. Hut the nali» of the 
afQUnia an •» (liin and of nuch n nutiirr thul certain of the const itii elite 
iftW blnid pim frtiiu ihe inlrrior tif the rapitlan' thrr>ii)^h the rap) I In ry 
nil III the clcnicnls of tbt- Iimuo ouUid* tlio capillary, and siniilarlr certain 
•f iht cuostiluentfi of the tissue, to wit, certain sutwtanoes the result of tlte 
■rtiimltiiii coolinually K'^inK on in the liaeiie, paaa from the tiwue i>iit<iide 
llNi;af>illarTUir<>uyh tlte <:apillary wall into the blood flowiiig throujih tbe 
afilhrj. Thua u we have already nid, $ 13, there ia a coDliuual int«r- 
daim of matenal between the blood in the capillary and the elciaeudt of 
ikuaite outside the capillary, the Irniph acting aa middleman. By UiU 
bhtthiaxv the tifuue liv« on the blood, and the blood \a aflected iiy il« 
(Mife tbnHi);!) the tiMue. In the aruull aruriea which end in, aud in the 
«*U niiM which Itejcin lu the capillance, a dmilar interchange take* place : 
ta the amount of iiitcrchajice diminishea us, paatlng in each direction from 
IW capUario, thu wall* of the arteries and veiux become thicker; and 
iKkH, in all but tlu' minute veinH luid arlerin, the intrn'hange is m Miiall 
ika ii may prBclically be ncgU'Clod- It in in the cnpilhinnt (and minute 
antria and Tcin^j that the bui<iiieM> of the blond Lt itntin^ it i» in ihi.'w that 
tW inierclianp.- Inkm |>tnoe: an<l the olijecl of thr vnu'iilar mcchnniiim is to 
nan the blooil to tl>.>n- ihroiij^h tht-ve in n nianner IkwI ailuplcd for currying 
« tUi bt«rchaiiuc under varying ctrcumstanoca. The ii«n of the art«nw la 
ii the main aimpTy to carry the bluod in n auitablc mauucr from the heart to 
thi apillnrici. t^e uae of the veina ia in the main aimply to carry tlic blood 
hn the capillaries back to the heart, and the uae of lh« heart is in the 
•ain viBply to drive the blood in a suitable iDaaitor through tlic arteriee 
<M« the ca[Hllaric8 and from the capillnrim back along the vcitta to itself 
■pin. The structure of these several p«n« is tidttpt«d to these several uaaa. 

Tht Sirvtiiift of ArUriet, C'-apillarta, and I'eiiu. 

}10S. On tom«Jt»t»rtM of mnfKWtfw (wti/-. The hrarl and bloodvaaeli 
ut, broailly speaking, made up partly of iniwcular liaMe with its appropriate 



nervous elenienie, mid parlly ufcciiAiH vurielim of the imut- known n« con- 
nvclive tii»ue. We nha)) have di xpcnk of Momv of ih- ftwlun^ of counective 
tiuMO of i-ihynulo^iftil )iii|Hir(nii('i^ whi-ii nc cnint' to dcul wiili tho Irniphiitic 
Sfsloni. for lliio synlwii w iiitimuU'lv iimormtct) with ooimi-clivi; liauv. But 
an iiiWH'iatkiii rnilv Ii-m <-1>w OxUli^ lictwwn llio blixjilvnitrh mid oonncctiw 
lisxip : for ojiintntivc ti«<iii- not nnly ontm Inr^ly. in ono or otiier of iu 
fonnM. into iho viruciurr of th<i blood vrsvlo, but nUu torrn:* * sort of bed bulh 
for Ibc Inr^r vctwln on tlicir way to and from llio several tisf ilea aud orgaiu 
and for Ibc siniillor rcwde, including thtr cnpillarics, u-iibin each tiasuc and 
or^nn ; ii>di.<vd. n cupillarr may bo regarded as a minute tubular [WMage 
hollowed out in the vi>i]Rcctive tissue whlrb binds together the elenienu of a 
ti»eue. It will bo dmrabK thorefbrc, to point out at ouce a few of the 
chnractc^rs of cunncctive lissup. 

Tlie coBDCClive liwuc of tbe adult body is derived from certain imviiblutic 
i-elU of the embryo and cDDsietS eseeiUially of certain celU, nbitdi do not He 
in close contact niib eacb other as do liie celU nf i^pittieliuni, but am 
if[iafated by more or lest) inler-cellular luaterinl nhicli tuny in <x'rtnin c«Ma 
be fluid or semi fluid but which is {(enerally wHd, and in oitiiinioiity ojiokca 
of as matrir. [n mu»l fonuB of connective tiwuo the matrix in rclutivvU- ao 
abundant and proruini'iit. that the (%1U, or mmeetivf H/trw. rorpuitciM as tWy 
art' callcil, become incouiipir'nousi; and, speaking gon^trally, the value of 
cnnn«ctive ligsue to the body degMtnclit innoh mora on tho ([ualitJes of tbe 
Rintrix ihiiu on tbe activity of the connective lL-«ue corpneolm. 

Tbe kind of coiincclivo tStnur, itomclinii'H cjilb^d " loose conncctivu tissue," 
which wrajw round and fnrmn ii WI for thi; bloodvessels, cunsista of an 
irregular iDCuhwork formed by tiitorlncing bundles of various snes wbidi 
leave bctwucn llicni ipacM of ver>- variable form niid aiie, eonie being n>ere 
chinks or clen«, uthcfs being larger but generally Haltened paawges. all cou- 
laiuiog lymph and having as we shall »ee s)>ecial connections with ibo 
Iviiipfaalie vessels. The larger spaoee are someiiiuee called "areolar," and 
i)ii» kind of connective tissue is aometiines spoken of aa" areolar ti»iu«." 
When a itnmll portion of this tissue is leased out carefully under the niicr»- 
scope, the larger butidli'a may be Hejiaraled into liner oundlM, and each 
biiitdle. nbidi gi'iieriilly pumui-^ n navy ourxe, has a fibrillated apjitnmnu; 
W if made up uf (?x(^t.itia^d y tim: fibrilltc; treated with linie-watcr or haryta- 
waitr the bunillendfiartually njilit up into fine wavy fibrillicof lott than 1 (■ iii 
dinmetcr, a aulMtancc of tt iieirultar nature which iirevioiMlvcciucutcd tbe 
(ibriihe tiiftether being dii9olv<«l out from belwuen th<!iii. Wlion a mass of 
micb libritln i* bnikil with water, llicy beoonie converted into ^tnlin. n sub- 
Htancv containing, like proteid material, carbon, nitrogen, hydrogen, and 
oxygen, with a siiinll ijunntily of "ulpbur, but diflcrinjj from ]>ri)tt^id material 
both in its percentage, compwition, and in it« proi>crlie». A remarkable and 
well-known feature of gvUiin i* that its solutions while fluid at a tempernturo 
nfliailing waltT or Iciw, become solid or a"j(illy " at lower temperatures. The 
untouched (ibrillic. In their natural condition, bohavo as we shall se« in 
B|>eaking of tbe digestion of connective tissue, somewhat iliiTerenlly from 
prepared gelatin : ihe natural Hbrilla, therefore, docs iiot consist of gelatin, 
unt of a substance which by boiling is readily converted into gelatin. The 
subetanco soluble in lime- or baryta-water, which cements a number of 
Bbrillae into a bundle. up|ieat« to be allied to a body, of which ve shall 
speak lat«r on, called mucin. Since the fibrillie form by far the greater jMrt 
of tbe matrix of connective titwiie, a ijuautjty of this tissue wl>en boiled 
seeniB almost entirely <Hinverled into gelatin. 

In collective tixaue, Uien. a number of exceediuu;1y line gelatin! ferou« 
fihrillui ore ceinenteil together into a fine microHcopiu bundle, end a auinbcr 



•f tbtM finer buiiilk« muy be aitnilarl}' cetDetitetl tocether or aiiuply appowl 
HfitWt to fnnii l»r)i;«r buDdl«e ; Mtue of the bundlee U leut «p|)«Br more- 
•nr 1.1 be dr-tinnl by ■ ile)ic«tc tnin!t|iar«nl ^alh of a Minewhat peculiar 
oiUtT. A tiiinilirr of these buiKllM, tinall and In rev, are arranged aan 
wihaotk, (hi- irD'gular tpacn of nbieb are oi^upieO by Iviiipb. On lh« 
«ln<i ibr tiiiiiiMtv rnnani iho ipiiCMi or b«tnw:ii llto )>viKli<-s wh^^re titvw 
m a iiifuBilti)!!, iil\r» lyiii)f in nitimlr tpuctd hullnwe<l out in ihi- ii-inoiit or 
pMnd Nibkiitnc)- uiiitior ibv binKlIra, aro rmiiiil the i-nDUiM'tivi! (twiK- cor* 
fchfc I'jich >if thcM- it a ri-ll niQtiiiitiiiu "f ii mic]i-ii>, trritcnilly oval or 
ilwpf r . •urriiuitili.ll by it pnitoplai'mH' ovll body u»iinlly inv^'uhir iti lurni. 
Majt Kinirliii)i.-a invrvty xpindli- fhit|icd. bill nxm Tttf^ueutly dnlindly 
kwM or iii-llatc. and iH-iirly hIwmt* inuoh HatiitKi) in ■ plaiw rorre- 
ifNtdin).' to tbr ilirrvtion of the fibrv*. or buadlc* of the Rinlrix. Although 
■ or hnvc mid lbi> librillir ara ccnmud toscth^ into ■ buitdic, nch Kbrifla 
mtia* iiilRdriitly dixtinct to hav* a roareoil rolractm- vlK-c< uii raya of 
%ld lUliDg upon or traiwinitml ihrough tbr ttmiti'. «u thai iho bundW 
iffor while and opaque ; ht-nco this titwutf, and specially n morv dense fi>rui 
(< it. it toraelimo s]>oki-n of me irhilo tibrou* tiemio. Oirinz bi this onority 
ik nofr df limle connective linue corpuBclcw arc not rctinily visible id the 
MUinl nxulituiu of (h« tiHue. They may, however, U.^ brouglit (o view by 
ikaclko of dilute acid «uch as acetio acid. L'mler the intliieiiee of lbi>) 
mIocIi flbr^lta swelb out. and the swollen tibrilliv prcv^ng u|>i>n each other 
na* Id rcfnct li^ht so mush M befbte. Hod thua become more trnnspnreni, 
niyiDWPh as an opaque maes of ttripa of tringhui beooinn tmnepareni when 
iWtffiia are swollen by bojliiijf ; ihia incnaaeof irannpnrcncy aJlows lli« 
■wpamn, whieh are not mrullen nul rather •hrunkeii aixl made mor« opaque 
fcf ibr artitm n( llie arid, to become visible. The prcwnoe of these oor- 
fad* nay nltm be rovcali>d by lh<! ui«: of MUch Muiuing rea^ccnu a«. whil« 
■M 4ainio^ ibo fihrillatol matrix, ftain the nuclei and the proioplanmlc 
kiCa of tbtt ciirptivJoK 

BmUm time hmnchrd irregtitiir-llnttrned oonnwtive timiio cor^iUHclea. 
«kMi do Dot oalurnlly exhibit any nnio-boid moreinentf, Icucucvte*. exbib- 
iuagmmor Inam-tivc moTcments. are fiitind in Iho spncoa of llMtianw, 
kftUer with cnrpitw-leaof a third kind remariinblo frxmi the la?]^ cnartr 
fmaaWa «itb which the cell Nihalance ii etudtlod, and known na " fdaama- 

(lot. When eonnectire liwiie ia rendered tnin«pare»t by the action of 
•iilnr acetic arid, there come into rieir befldes the <»rpiiiie]ee, a number of 
Ua« iGfletvut I'nHn the ([^laiiiiiferous fibres not only in not beins swollen 
•adiOKlered tranapareut by the action of (he acid, but also by tneir slae, 
thlinly acuity number, clear bold outline, and sharply ctirvetl oourw. The 
Amwjr much ia uie, aoine licin)t very fine »> as to appear mere lioea, 
vkQi Mben are very )arj;e with a diutin<.-t double outline. Whether small 
vbiye cwb 6bre is a linvlo llbre, mx a bundle, and cannot be split up, like 
albviirHnill bundle at the ordinary matrix, into fibrillie. ^ol only id 
thiir nxirvF iharply i-urrcd unlike tlx.- gently aweeplng outlinea of the gela- 
liaifmius fihree, but iltcy divide and aiinntamoae fte«ly, thus furmiDg Dct* 
•wi* of vnrvtnic shape : the gelatiuifemus fibrillie. a» the other band. uev«r 
diriia. aiwl tlie Bundlea int«rlaee into a network rather than anastomuae. 

Tie Bumbrr of tbvvo librea occurring in fonincctive iiwue varv much (b 
difcent «i(UBlionii, and ia aone pliiii% a.*, for instance, in the li^mfntmm 
■aricr t4 certain anim^ iMBrly ihc whole liii:<uc ih ct>mii(ii«d of lar|^ librea 
(f tha kind, having in the man a yellow color, (he oniinary gelatinilcrous 
ihiv biiiig redurca to a miniinuni. In nich a ttttualiou a remarkable phy> 
<Wcku«ctar of tbtoe fibrei it catJly reeogniiMMl ; ihey are in a high degree 



GxtMwi1)l« Mid elaMic; hence lliey are fret|uetillj' called e^aW>>jt'i>'^>: lt»»Bl 
ihvtr )'i-tlowUh nolor thev are sometimes oalled fellow elastic fibres. The 
whitr grlntinifi'rouH iibrilfwi, uu tbe contrary, pMseas vary liille ex(«n>it>ility 
or olairticity. 

WIk-ii a {Hirtton nf HKiuoentiiiu diiuIi% \a frettl hy iirolonged boiliug fv>ra 
th<! n-mniiiil of gclBtiniliiroii* fibrt« mixed iiji wilh ilio velluw claolic inaU- 
rial, tbs Inll'.T t« limiul on cbemiail tn-iiiineiit to yi«l(l a mibtiiaim called 
tlattiti, nhicli very clowly nveinblts [iruteid matter m clemtDtarr cotuno- 
sUton, excvpt llint it contain* no fulphur, and wbicli yet probably diftera 
wid«ly IVom it in nntiirv. 

Conneclivo tiwuc Ibwi con»xti> of a matrix of iuexlciisiblc in«la»tio irhile 
navy );GlatiiiifrrouH tibrilUv, ccmcnU-il inm bundlr* (iht- bundl» Xitat^ 
arranKeil. in Io<«o coiiiiecitrc tiAtic, in irregular mt^hunrlci) nilli which are 
ttwociated in varyitii; abundnncc anastnnnMiiiig euHcd ypllow clashc tibrea, 
flud auion^ which arc embedded limnclirii coniictivc tietuc ciirgnifcle!!. I^U- 
ooejUs aod pluma cells are itl«a found in th« raMbn or aroolie of the dimIi- 
work. We may oou- r«lurn to the striicttirc of the b1ood<r«Mela. 

% 107. (^tpUlarie*. A capillary if, iis vc wid abttve. a tubular psfsage 
liollotved out ID counective timue. Without e|)cc)ul prejMralion all inat can 
be K«n under the microscope is the outline of the wall 
(ni>.U. of tbe capillarv, shoirinj' under hi);h powent a double 

\ \ contour. and marked with oval nuclei which arelodced 

in the wall at inU-rval». and which project aonieirOBt 
into the lumen or canni of the vessel. IF iff. 51] Wbea, 
however, the tis^'Ue coutalninK the capillaries u treated 
vflih a weak eoUiltou of silver nitrate, and after being 
thoroughlv washed b exposed to light the wall of tho 
oapiUnry U seen to be marke4l uut oy thin black line* 
into »pitidlc-«lm|)ed areon, da\-«ituling into each other, 
and mi rrlaliil lo (lie nuclei in the wall, that each nu- 
cleus occupie:< about lh<- ocntrc of an area. Krom thi> 
and from other liicU vrv concludv that ihe laipillary 
wall i» built of Hal luxifnrm nucleated plates cemented 
together at their cdsrs by some cement subalancc^ 
which more readily abaorbs and retains silver nitrate 
than do the plales themselves, and hence aAer irtAt* 
mcni uilh llic silver salt shows in tbe form of black 
lines the silver which has been absorbed, and suddenly 
reduced. Kach plale is u Halteoed nucleated c«ll. the 
cell body of whicn, except ti)r a remnant of undiilV-rni- 
tialed protoplasm round ihe nucleus, haa becuimr con- 
vened into transpareiU. diOereotiated material. Sinoo 
the cells, except )br the minimum of ocnK-ni i>uhi>ianoe 
botwceti tlicm, are in dose coiilaet with each i>iher, 
wcmiglit Rpeakof them asformiiifc ana'pitliutium ; but 
on account of their cell InHly boiut; reducnl to a more 
plate,and(>tiaecountof their connection both hv origin 
and nature with mcNoblaHic conncctivp ti<vtiv corpua- 
IHm, it is convenient to speak "f ihi-m ns rpH/irlioid a-Uf or plnto^ They are 
■pmelimes R|>okcn of as rndothrliat cells or plates. In a small capillary tbe 
widtli of one of these epithelioid ))lal<« al its widest part, where Iho nucleus 
lies, may be of nearly the wtmc size ns the rircumfervncc of the even-distended 
capillary ; the cells consequent! v arc placed not side by side, but more or len 
altarnate with each other, and their nuclei priiject alternately into the liinien 
of the TCiML The larger capillaric» may, however, be su wide that two or 




Hratimiiror * uvi>r.i- 
nu. triKii Tkutub't 
Hfia Sonmon ft Ni- 
laiTS uj' SiLvn. 
d. CMt. >. Thdr nil- 




i-ellii lie iikore or l^se abrcasL OuUide the CKiHtlnrv, U'liich is tbus 

ft Ikto whJ dclicale menilinine. a m«re {latcliwork of thin epithelioid cells 

OMBottal toK«tJ»or, i» alnava fuunil tk certain nniouiit of couuective tintiue, 

tlw wall of Uie capillar/ furniing at places jkan of llie witllfl >if the lymph- 

boUiM eannective tiwiieqncta, aiid at oltier places Imiujj uiiitt^<) by cetui^nl 

aataml tn the buixllt*, bands, or alwets of tbe same coiiitcciive lusuc. Not 

itaf>«|ijmtly, in youuii; iimmka, branched counective lisnne c(trpu»c:les He 

•i[*ia utd rtntiraor u CAj^llBrv, fonw uf tW i>ri>cesiet of the ckII beiiij; sitai'lied 

U> tho KUlaidi,' of tbc rpitlx'liiiid iilaliv of t^i> eit[tillary. Kvcii in llic rapilla- 

of aocb a Uiatie as niuscle, tW ni-lwurk i>f ciipillaric:! i-nilirii<-iii^ a nius- 

flbra b alwavR surmuixli-d by a crtAiti ihuii^h sonictitnrg' a miiall 

•MMai aaW of nmm-clive linue ; iiidwd, nhcrcver capiltnntii nin. tliey nro 

aOMatpaainl. mt wv haw wiid, by coonertivp tiiwu«, to itint overywheru all 

0**r lb*? b«dy Uie blmxJ in tbc capillnry i« «c|ii>riit«d frnin the lymph in th« 

tfttcr* of the c>onnectivo tissue br iiolhiii)f more thati the oiceetli ugly thin 

Wiw of the cemented epithelioid plates, ll must he added, however, lliat 

th* ifiaees in the cuoDeclivo tbsue are lbeim>elvca fometimefl lined by similar 

wuliclioiii platea, of which we slinll have to treftt in sfteakiog of the lym- 

|M(KB, ttt that in placw tbe partition between tlw blood and tlieM lymph 

mar Im' a double one, aod consbt of two layen of thin plut«t. 

Ife KDJ ciiae, howovcr, the [lartitJon U an exceexliii^-ly thin one. and no |ior- 

nniMi that it alhm-s nii Hile<iiiately rapid iuterchau)^ of inntenul lietwi.i'n 

lWbto«lai>d the lymph. As wu ithall pri-rt-'ntly M^e. not ufily tluid.t— that 

ii^mtten in wliilioo — arc able to piura thr»U);h the riurtitiou into the lymph, 

UtinUct eurpusetm Wh rod wid while, ea|>ecially tlie latter may, in ovrtain 

cinanMUnc**. niabf Iheir way thniugh, and m> paae from the inurior of tho 

■fiBatr IdIo the Irniph »pace« ixitxide. It is probable, however, that then 

mkt ueir way chivtly. if not cxvlitiiirelv. through the cement lines, and 

■IMJally at ihe point where the <«inenl linc» of three or more cells meat 

(DMlier, and where the cement Fub»ljiDc« exists in larger amount than elafr- 

TW «te of (be capillaries is variable. In some regions of tbe bodj, for 
OHUiiet, in the Iudk^. the capillaries arc, on the whulo, wider than in other 
nti'ias, fur iiRiaucc. the xkin ; and all the minute vessels joining arteriea to 
wisi and pfwwMint; the structural featurra jiist described — that ia, bdag 
mil! spill arte* — will out always have the $au>e size, even iu the rante region 
<l (W Dody ; tbe artrrr may gire rise to Uiffe capillaries which branch into 
•■all QBpiUnrMM, and these iniir again join into lar^ecapillariee before uniting 
tifctn raiiH. Thus one i-api^larr outy be so narrow tnut a single (mamma- 
Su) red oorpuaclo passe* through it with diliieulty, whereas anuliier vapiil- 
hr? may he ttid* enough to afford rotim for two or three such corpuscle* to 
tr- i>i. Itt-viiles (hi*, ilu' same capillary, may, in Ihe living boily, 

ii i:ii frxiii time m time. At one mi>meni, as when (lie etiininoe on 

tt utrrwl rii\r is blm-kcl, or when liIrnMl. fur Home mason or another, ceasea 
lalow iDt>> it. (he ciiiiilhirv may Ik- i.-nipty and eollaiwed, its walU in eon- 
tut and its lumen nholishol or nciirlr so; and, in liawes taken from ihc 
■bbl budy and preparwl for niicmtcoitical examination, tbe capillaries are 
smmlly thu« cm|>(y of blood and (-iilliiji*"), »i (hat they can be seen with 
etCnilty, appeanuK as (hoy then do as ulinu»t mere tine* with swellingd at 
>iu«rvalii comspoiulini; Ut tlie nuclei of iho eoostituoiK celU, At anotbar 
(IBS. as when blood is flowing into it a( high prwetm-. the capillary may bo 
viddy diitnidfi). In the variations in calibre, the walls of the capillary 
fJsj ■ paHTv |iart : the maleriul of the eirithclioid phites is extcnsihk*, and 
lis fnman of tho bl<Kid within the capillary diBlen4ls the wa)U, aotl the 
~ baing also elastic, tbe walls shrink and colUpae when the prewire 




ia itnovcd. being iiMwtcf) in this by thv prMsurc oT \ht lymph in (he ipM«» 
OUlnd« tlic cnptUtiry. ItnC iHifidcs thi», in i> vnung nniinnl, itt all wcntf, Um 
citpillnry wnll is, to » oi^rltiiii cxtpni, cvnirnuiito ; thi: <:{utbelioid ci-Ili', which 
ihtrii a[>|M-nr lo cont«iii a liti't'O imiutinc of iimliftl-ienlinUxl protoplaixii. »n-m 
able, iiii()<.T the intlticnco tif Mliiiiiili. to vhati^ tlirir fiimi. piiMiii); t'mni n 
loiigirr aikI narrower nhape lo a fllvirtcr and hruiidpr otic, and (nii» iiiHucndng 
ih? calibre of the iiibc ot* whioh lli«y Ibnn the weiIIh. How far f\ich an aclivv 
chaii^'c of form lakes place in the cnpillariot uf the adult body haa not yet 
been <letiiiilclv determiited. 

Tlie ^iruQlure of the eapiDary then seems adapted lo two ends- In tke 
firel place, ilu walla lieiiin penueablu iire adapted for cnrryioK out that im- 
portant iuterfhaiixc between the blond uud liaatie. which, aa we have more 
than nuoe Mid, laltcs place uliuiwt oxduMvely in the cunillary rejijioiM. In 
tbcsec-ond pluru, the extenBibiltiyundelHAtiiity nf lut wallit permit it to adapt 
■U ealibru lu tho amomit ami r>iri.-e witli which the bWd ii> llnwing into iu 

^ 106. Arlm^. The wall nfmmintUi^ artrrtj, i. c, nf one whiuh imHHin abuul 
to breulc up inlu capiliaricv, and which i:< •onieliniM i^pokcn of iu> an (irtm'«t, 
coiuiitt* uf thtt following parts : 

(Ptd. u. 



1, ■twlkMlnfUTT ', ^ Ummiaun voaicl ; 3. «sn«r raiilllnnw : 4. Hiier cB|41l«tla a. Mruciurekio 
nmbniie Mill wlUi waan i>ii«lvl. rt>[im(ntoll*e o/ Ihe tantca vitliiu: b, uuold of Uie biuku^t 
Mf»««IU; I', iiuckl wlihlu tlin miiaII artciy, larbjti* apiionaiiillig lo ui mdoUwlliuiii A nuclei tu 

Fbl ^— aiUU. AaiEKT Tn SaoH iiiK V<iiiui-i l.trt;iT!i uuicii I'DHi-itn n* IVauo. ■, tniiy 
tfetSmn ;;ft. InUmal cImUi- luuiD*;f.rJrp>ilaruiiuculnr fibrrt ariliemlil>ll«ri>at:it. ib«vonn*ctlt>*- 
danaiHUHrcpM— tunica •dTnillU>iLuiM«'«i«»>Mi'iv*. «!''■■ b? iSUiliiuif,) 

There ia within n lining of fnHifono epithelioid oelts. very eimil»r to thnw 
of a capillary and aimilarly ccmmted together into a membrane t^'>^- S-]- 

lirac (liBiticicr of tbne fueiform cells, irhich «re Mmoiimee very narrow, 

!■ pIacwT luirnlli-l in tlii! axis of tlio artny. 

Oauitit' tbu> ipiilii-lHiiil liniiif; uoiaea * iliin trenitpBrent aM-ueturelew or 

finely lihrillali'd mrmhmiie. Aeeii tii an itpticfti or other secti'm of lh« ftttm* 
_ a* a mrrc liiir, wliirli ivrviw hi> a fiu|>|x>rlii)i; m«tu)>r«n«, baiaciDcnl inciubranc, 
■ W mtTfirtna finrpria, for i1m> «pi(lt«lHii(l velllt. Tin* inl-iDtiniiw \* similar in 
^U^niiii->l nnliin' nncl in pmixiriin In tittt olrurtii.' fibnu foiiiiil in con inactive 
^flfair. aoil licniv U »|Kik<'n of an the tloMie memhrnnc. Tliv f [lithi-ttoid colli 
^^Sd tW clultc fi>«ml>nin<- t<ip?lh*r arc often cfiukvn of m» forming tbo inntr 

mtt (ttmiVn i'n(iui) uf thp artrrr. 

IVi'ni)>|iril inmaverwly in n antn or Ipm clutinctlj wpirsl manner round 
lUi iiibrr niut, and imbedded in n Kmiill c^uanlily ol eonnective tiwue. tie a 
nitnber <if [ilaiii musetilnr fibre*. nrrnni.'''<l id the i>malle«l arteries in a einijle 
Uftr, in the larger but itill »iiiiil1 iiitcrie* in mora than one layer, liiia 
iwtna in tkese arteriea ihe mUlille or niiisctibir eoaL ( tiini'iM mMia). Outude 
Am nuMuhir coat come* the external eoat {lunifu esiinui) conaiMing of con- 
nctiva liHue ilie buudlee of which are disposed for the moat pari I'>n}{ituili- 
DillT And contain a nitmlior uf eunne«tive-tinue corpiudea and u relatively 
brp number of elsHtic librra. This outer cuat ia continuouH with the coa- 
Mtivr-ltMue \yiA in which the artery lies. 

A uioule sKery then dilfeni from a eapillary. In ihi? ihickncw of lUt walls 
vkmhr (be pertneabilitv tu cbaraetvrjstie uf the cupillary i^ tt> u gn-at extent 
hH. ia the itintiuet development of elulic elemeuti, tbc! Gla*l<e rocmbranr of 
A«iutf coat, and the clastie librvn uf the outer eoat, vhervhy eliulic >juali- 
ti« wt definitely ntureil tu the walk of the veinel. and laHlv and chiefly by 
iWMtmiee >4 diriincl muscular eleroento. It ia obvioiix, that while by tho 
<lnwfiMPl of ela)>ltc clenx-'ntii, pimve rlinngM of calibre have a grealer 
mpttkan in the capillary, active ehan|.'c« in calibte, irhich in tbe capil* 
jnrm al best doubtliil. arc ujsured to the artery by llie muscular elementiL 
Hmi these trnnsvenbely digpnoed muscular fibres contract, they must narrow 
ih calibre of ihc artery and may do that against even rery eonsiderable 
tWraal prc»ure: when tliey relax, Ihey allow the internal preaaure which 
■naiM. ut diHieiid ihe veuel and tenipomrily to increase the calibre. 

nbeii Ruch i> Hmall anery break* up iniu capillanftt tlie niuiicular fibrca 
uA flattie nicmbrarie dtwopear, the remnant uf the niiMculnr coal being 
noMiBtit coiilinueil fi-r a shorl diittunce in thi- furm of a single libri' stnig> 
(liwtD a i>]iiml fiu<hi"u muud the artery toward tlie capillary, and all that 
altsii the epithelioid lining of tlic inner coat with a little oonDcctive tiMiie 
■•nnment the outer coat. 

i 108. Tha toryer artrritt rcMinble tbe minute arteries in to far that their 
■dia maj h(> cons>(lere<l n* eompoeed of Ihrre voate, but rjich of \iuxe coats 
iiif • miirv itT lew ounplvx nature, and the minor detail* of their struc-ture 
ilh in dillrnrnt artorie*. 

biMieh an artery as the carotid or radial, the three coats have the fblEow- 
■jtmeral characters [Fig. -MiJ. 

iW inner eoat is composed of a lining of epitbeJioid cells resting not on n 

■a^ delicate basement membrane, but on an elastic layer of some thick- 

>■. I iMWistilj||, diielly of a so-called " fenealrated " elantic membrane or of 

M« ihao itne ttich ntembrane, together with some amount at fine elastic 

laad in some enses at all events a small uuBDtily of white conneclive 

L A " fen<-«trated " membrane is a membrane conipnewd of the Mine 

am a* the elimtic fibres, perforated imeKidarly with bolea. and more nr 

l^aarkvd with indicatioosol fibrH; it may be reyanled aa a felinork of 

•latii: fibn*. fused or beaten out, as it were in a UMrv or K-m mmplete mem- 

Wua. BDina of Uw meidm of llie feltwork remaining us ** fenestne " and 

and ^A 



tncwof thellbna being xtill hfi. Suc-li ri-ncAlrkted nciiibnats, »ntnc thick, 
•OIU4 thin, occur hut!) in tliv iinK-r niid riiiil<ll(> ooaCa of tho Uw^r url^rius ; 
Dti'l ill dm iiini'T cant, ti»iinliy iinmctiiitolr iindpr th« e|>ilhvii<ml lining, ibei* 
is in niu«t Inr^v tirtvri«« n vooNpicuoiis mcmhrnun of tliis kiiiJ, sometimes to 
thick nit tn give n wry distinct iloubic ojlline in mentions of the arlcrr even 
umlor nioilernlc powcre. nrn«filh this there tnny be other eimilsr fenestniied 
membrnncs, or u felt of tinv cl«tic fibres held together hf a very siuall 
({iiiintily of white coDOCctive tiwue. In iho norta, and in some other arteiiee, 
tlie cpitholioii) mIU rat imraeilialQly not oa an elaatio membrane but i>q h 
thin layer of eo-called " iiub-epiihelioid *' tteauc, which cun^isla of oi>iiii«ctivc- 
licBiie cor|>u8f!e§ imbedded in a homogeneous or very faintly 6brilla(ed 
matrix or };round eub^lam.'e. 

The epUbelioid <.-ella are diiposed loni;itudiiiallr. that is, with ttieir loi 
diiiiii^iers parallel to the Kxis uf the artery, and a similar hmgiludia 
armtigi-ment obtains to a greater or \tss cjttent iu the undprlyiiic elnitlir ele- 
mentA. When utler death the arteries, emptied of bloml. bei-ome narrowed 
or cotutric'ted by the r-oii tract ion of the muKCiilar element of the middio 
colli, lh« inner coat is throwu into longitudinal wrinkle* or fotdi. M UiKl io 
tniiiitvi-rr>u necliuiiM of an artery in thin condition the inner (wal hai • dianwy 
t«riiitic ptiekereil appejirance. 

The inner cout in .lomewhat delicate, and eunily torn, »t that in injiirin to 
arlcriiv, an ndieu nn artery in forcibly ligatured, it in ant to be brokeJi. 

The middle ctmt, which in gcnernlly ninny time* tnick«r than the inner 
coat, <im»ixl» of clnNtic Inyere an<l mn»cruiar htyer* plnircd in more or lem 
regular alternation. The muscular biyert L-nnsist of band* of plain muscular 
libn» placed tniiisvenely and united together by a very itmiill amount of 
white connective tiseuc. The ela«tic layer* eonsiot of somcwhnl (bick fenes- 
trated membranes or of feltworks of elastic fibres ninning on the whole 
loDfpludinally, but not uufiequenlly more or leas ublii^uely; these are aUo 
bound tof^ther by a aiuall quaulity of while coniiectire tiineue. 

The ou[«r coat eonaista of feltworks of eltietic fibres, or in fome iostancee 
of ftDeelraied inembrauee, diftpueed chiefly lougitiidiDally, and aeparated by 
buodlee of ordinary white connective tUieue, which become more and more 
Itredominant in the outer portions of the coat. In many arteriea bund* of 
j>)uin mn!>eulHr fihrr» ore pre!<ent in this coat also, and then run for the moat 
\»n but not excliixively in a longitiiiliual ilireetiuu. 

Bloodvci«iel» for the noun.ihmeiit of the tiiniie of the walls (mm wuorun) 
are procrnt in the larger arterieii, beiug iu<i»t abundant in tlie outer cont, but 
penotraling for »ome dint luice into the middle coat. Nervex, eonaia^ngcbioBy 
of noD-iDcdullat<t<l fibre*, may he iraired through ihe outer coat into the 
middle coat wberv they apptrar to end in connection wtib the muscular libree. 

Lastiv, in iJie case <if mwt larger nrteritv, the bed of eonncotivc tinsue lO 
which the artery run*, t; fomicil into n more or lew distinct shnith. In this 
•bealh, tlic white connective tiiwic is much more abundant than are tbe 
rellow elastic elements, so thnt the sh<-iith i' far lens clastic than the artery. 
Hence, when an artery and it' sheath are cooi|dctely cut acroe*, (hb artery 
is, bv elastic shrioking. retracted within its sheath. 

Tlie nut important structural features of a largo artery may then be 
Bummed up, by saying that the artery conMsle of a thin inuer cuat onosisling 
of an eiiitheliind lining reeling on an elastic basia of no ooutipicuoiu thick- 
nan, of a thick mi<ldji'! coat consisting partly of muscular fihrw disposed for 
^e moat part tranHvcrxely, and partly of stout elaatie elemeutA, tliia coat 
beEog the tliiektat and must im|>oriant of all three coats, and of an outer 
coat of variable Ihieknec^ cou^intinK chiL.'fly of elastic eleueota ioiermixod 
with an increasing aiuouiit uf white connective tissue. 





rteriM powow the uhore fealum.- It n>aj furthpr he «ai(i, that as n 

nile lli« Minfctilnr ctemeni bean a lurger [Toiwrtion lu the clastic 

io the (lualler tliao in the larger arterif«, that is to eav. (he itiiialUr 

Otarin kn more cboapicuoii^lv museular. aod the lar^r arteries more coii- 

il^ODCNMljr elastic It rauat W n?iiieiiihered, huwrever. that the several arteries 

vf IImj boily difler coiisidenihly in minor ledlures. siich as llie relative die- 

poattiun ftnd UDount of tuuscttlar aud eluiic eieiuenu in the middle coat, 

tlM amount of miwcular ibsue in the outer coal, and Die proportion of white 

ovavctivo Umup prcxent and the like; iu llie aorta Tor imtanee, a vonMder< 

able quantUjr of while n>nti*«iivo tiMiu« U pre*eiii in (be middle and, indeed, 

b ill* laner coal, a» well tu i» the outer coat. I-eavJog the*e (unaller dilfer- 

neca on one aide wo may tmj. that while all thnM^ couih, but cw])edBlly Um 

teporUDl middI<^ coat, ooDtribute to kIvc- nii nrtcry it» chflmclcrintic elaHtio 

■ Ml k iw. by virtiH- nf which it expands remlily under iiilcriiiil |>r(«.-<iire, and 

■riab again wbvo the pm»tiro w rvmoved, it i* (h« niiddk coiK which 1>y 

■laMef lira abtiiidnnt circularly dispoced inu^ciilur tihriv, now through tliv 

(■inrtioii »{ thow tihres narrows and conslricti!. now through their rclaxa- 

Am famiilfl thf widening of the vessel. The iinporlaDce ut ihe inner cunt 

a fmbably cenlrMl in the epithelioid lining ; in ircatine of blood (^ 'i'i) we 

«« RMon to think that the bloodvesets exerted a mariied, though obscure 

iilMMe oo tfae blood BtreaniinK lhrotif;h them ; that inlluence in all proba- 

tA; IB eflteied by ihe e[Hthcli<)id nelk The elastic elements of the inner 

(Ml are pnbably chiefly of value in jwnnittiuK this coat to follow the 

iImm of the nxkre important middle coal. The outer coat while increasing 

lb* wutic power of Ihe whole vewel, in especially useful, by means of iu 

nail blond vesae Is. in (-onveying nourisbmeut to the middle cuut. 

illO. The m'iM. Thc)« vary in diflVrent purm of the itody to very 
■iJily, that it is difficult to eive a gcneml dncription »f strurlurc suitable 
bxDvnnsi It mav Ih- ui«l, huwevvr, ihal ihry dilTer from arteries in having 
Wtth tfainnrr walls, and in ihusc walls containing rclnlively much more 
■Ut* otiDDeclive litduc and much lew yellow elastic tissue. 

A large vein [kdvcsbcs like an arlcry an inner coat consisting of an epitho- 
M lining, the celts of which are eliorter and broader than iu the cornv 

riding artery, resting on an elastic basis, which is leu conspicuous than in 
EMTMpoodiiig artery, and conaiMB of a tine feltwork of tihrw rather than 
afaulrated menibraue, and ci>niain« mure white connective lifsue. 

laa medium med vein auch as the sikphena vein it is porsihle Io disljn- 
|iUi outside the inner coal, a middle and an outer coaL The former 
eaMUof white conueetive tiMiue. with a scanty supply of elaalio Sbrea; il 
Hnuias, aometimea iu couMdeiable ijunntiiy, plain rotiscular 6hres, the 
kmdka nf which form a meabwurk, with the m«»hep disposed for the iDnu 
fan trannertely. The latter consists also of white coiiucvtivc ti«*ue with 
■W elastic fibrta running lnOfritudinally and <)hli<|Uely, plain Ku»c»lar 
flms being sonietiniM |irtM-»l and wlien prevent diajHMNHl chKfly in a longi- 
laiim,\ direction. Small vasii vusonim arc pro«util in the outer ouat and 
Ottnd into the middle eOBL In many large vein* lliero in no sharp diMinc- 
lisB betwcvn a middle and ouir'r i-oai ; the uhnlc wrapping round the inner 
Mt cennile of white connivlivc with n vniiublc (|uautily of clastic liHUc, 
ud i^f muscular fihre* which luu chiedy longitudiunlly or obli>|ucly and 
•kick may be very scanty, or vhicb as in the vena portie may be abuitdant. 
TW Mructure of the v«'ins iu fact varies very widely; on the wlmle tl^y 
Hy be said to be cliennels. the walls of which are elastic enough to adapt 
iMMlrcs to considerable variations in tlie ()uaiitiiy of blood passbg ihrtiugh 
Iha, wilbout poasewiDg, as do the arteries, a great store of elaMk ]H>uer to 
■*■! fTtat variations in prcuure. and which are not so uniformly muscular 



and ooiitractil« ax nre tlie iirteri(!!'. - And we ahull see Utnt this [:«iierul char* 
aoter uf paaaive channels is adapted tu the work which iht.- vuiti« Imve (o do. 
Tht* (:«Dcral chai'acl«r, however, U modified io certain situntiuii* (o m«et 
purtieiiitir wanls ; tbu!> while the vein4 of the bones and of ihi: hriiiu are 
devtiM of mtiituuiar fibres, uthera such m tlie v<-rin |>i)rl:i' mny be very niuv 
I'ular; and in .■niriie veioH such iio llia-x; iif th« cxtri'tiiitic^ ii c'l.invtdcrahk 
<(ijHiilitv tif eliL->ti<' liHiio io ]ire>wDt. 

A minutK vfin jiint einergiii){ I'runi i-a^iitlikrics dill'ors very litllv from an 
artery of i.-iirfV9piiiiding siw; it is of riiiJivr wider bora, hiu ikcidvdly I(m 
muMciiIar and vluvtic (i#iio, and ihn c pillmlioid rails arc shorter and broader. 

Many veins, eciiennlly thosv of (he limbs, are providi;!) witli valves [Fin. 
&i ami 'io\. which arc pouch-like folds of the inner coni, the muulh of we 
pouch looking away from the uipillnries toward the heart. The wall of each 
valve cunKii^ts ofa fining of cpilhi-lioid colls uii the inside and on the outside, 
and bcCweoD the two a Inycr of while connective tissue sirenf^chened with a 
few elastic libres and somewhat thicker than the connective-tissue baeis of 
the epithelioid lining of lUe veins geDerally. The valves may occur sin^^l/ 
or may lie iw» or even three abreast. The veins of the viscera, those oftba 
cenlml nervous system and lU membraiiM, aad of the boDed, do not poMcaa 

TimvtTii VjLTisorRK- Alter Dalton-I 

lattlac lilt t9y laWnl rbaanel. 

i)it>wm of Mend 
AMr Dil.TOW.] 

SUl. The details of the Alructni-i- <if the fiifi^uliar muscular tis«i« forming 
tbe grcaU'r part of the heart we nhall n^ierve to a later seotjon : but we may 
here sar that the iiilerior of thf heart ia lined with a membrane (frido- 
Mftiiwwi) ciirrCBpiindinK to the innur i-oat of the bloodvessels, and consistioK 
of u lavcr i)f epithelioid cells, which, however, are shorter and broader than 
in (he Moodvntwls. being polygonal rather than fuHifurm, resting on a con- 
nective tissue basin in wbiob are present elastic fibres and in places plain 
muscular fibres. 

The valves of the heart, like thow- of the vein^-. arc liilds of (his lining 
roCtnbraae. sirenglhcncil by a cmatderablc development or(<onnectivc tisane. 
In (he middle of tbe ihin frw border of each of the srmilunar valves of (he 
aorUi and pulmonsn- iirtcry biiiidlefl of this connective liKiiie, meeting 
(ogMher, are mixed with i-artili^ cells to form a small nodule of flbro- 
carlilaice called the rorfmi ar'intii. 

In the auriculovenlricolar valve* muiiL-ular Bbres pass in among the ooo- 
neelive ttwue fir sonw liulc distance from the attached border. 

In one mipect the endocardium dijfont from the inner coat of tbe Idood- 
reseebt; the conneeiive (issue in it licar* bloodvea^ela and lytu{diatira. In 

rtATintss or vascular APi-AKATrs. 183 

tbfOM nf ihci auriculo- ventricular t»1vm littat lilondvcBeb of ibo tad<h 
ariiun irAVnno the whole ralve, but in Uiq caae of Utc setnlluiiiir valvw 
•up thort w-*r lh<' Atutdwd bonier, m that tlic greater purt ii)' tbc vuItv ii 

J/inn t'raturf* ef the Apparalut, 

ills. W« IDB7 Di>« raw* briefly in r<>vi»w mime nf the mnin fMtunw of 
lU Mvuttl pans of toe vn»niliir appiimlui, heart, nrtcriM. veinc, aad 

The heart ta n niUHiilnr {>iim|>— tbat is, a pump th« forcv of whnw Urokw 
pMpplinl by the iTininu'tion of muKtilar fibres nnrltin]; inlennitleolly, the 
■trans bchi): repvalcit n> many tim«s (in iiiaii about T'i timea) a mioute- 
[1 ii an ron^ruclr*! ami funitshed wilh valvea in such a way that al each 
itn>ki il ilrives a ceriaiu iiuanlity uf bloMi with a certain force and a certain 
a|>idity frwu the left wniriclp inro the aorta and so ini<> ilie arlerio*, receiv- 
b|;durio|; the stroke and the interval lielwi-cn that dtnike and the next the 
anrquHUtily of hlouil t'mni ihe veius into ihe ri([tit auricle. We omit for 
ani'licily'!) take the |H)lm<>tinry circ^uluiton by wliii^h the aarae mianlity of 
Um k driven at the llI^tkc fnim thu ri^ilit vciUnde into the lunpt and 
itciivtd into the Ittl nuHclc. Tlit.- rliyihra of the lieiit. thai U the fre^iiiency 
of NpMilku) of the alr»ke). aod tin.- cliaracter9< t>T each heal or «trok«, are 
drinmiaed by chanxv* lakinj: pinoc in the tuMum nf the heart itMlf, thouf^b 
tlvi air aW tiitlurnof^l by cauMs uorkiiit: from witboitL 

Vtf •rli-riv* tin tulws, with rctattvelv :<toul uhIIk. bninching from the 
Mfta all ovfrr the body. The (tonnliiulion of tbi-ir udIIh. ax n'C have rttfo. 
•pdatly of the rDiddleGnul,givi,w the ancric* two client propi^rliea. In 
ibtlini plaor they an- tfry r/'utie, in thi- iK-nw thitl ihcy will mrvlcb rrwlily, 
koih IfDj^hwaVi and eroaswtae, when pulled, niKt return nuulily to their 
fcmvr aize and abape vhen ibe (hiU is taken ofl". If fluid he driven into one 
foJ uf a piece of artery, the other end of which is lied, the arierr will swell 
oai til B very |;reet extenl, hut returo immediately to il» former calibre when 
ihtlaid ia let out. 'I1ib elufiiciiy is. m v« have aeen, chiefly due to ilie 
flMiie eJrmeuta in the ooatit. elniuic Diembranea and leltworks, but the miu- 
nilnibns, being ibenuelvee abn elastic, conlrthule to the result. By reuou 
rf Iblr MMOiIiig Hich stout, elastic walls ibi? nrteriw when empty do not 
MiDipw, iKit ntmnin iw o|>eo tulien. In the second place tbe nrli««. by virtue 
ifllitir mutoiilar elemeata, are ranlrarii/'- : when itimulaieil either diTts:llv, 
tthfmfiviag an elvctrio or ntcchtmical •timuluit lu the arterial walla, or 
Wn(Uy,i)y luoans of the Mvcallml vaxo-niotor nenm, which we A»\i have 
la Nady prMvnlly, the urli-rii-a shrink in calibm, Uie i-ircnlarly dispowd 
"awllii' fibtta contract iuL'. iiml Mi, in proixirti'in t4> the amount of tbcir 
iTClractMD, Darroaiii); ihnlumcn or bori' of the vctvel. The i'»iiLmi'tiou of 
■Wr arterial louacular tibn'o, like that of ult plain, iion-nlriuUil muM'iitar 
IIW. b eluw and l<mj;-<>->niinuvd. with a long Ut^'nt jM^od. ii^ com|iar«>l 
«uk the conlmction of Hkelrtnl Mrialeil mu-HMilnr AbrvM. Ovrin); ta thig 
■■nfair eleim-nt in the arierini wall«. the calibre of an artery may he very 
tun* or very wide, or in an intermediate condition hdmwo the two, 
adlbvr very nanuw nor very wide, according aa the muscular libru* are verv 
wuit niniracted or not conlrncted at all. or only moderately eonlrac*4Ml. 
V| have furllier aeen thai, while thi- relative projtortion ol eloMic awl 
Maoplar elvmenU diHers in <lil1ereDl arteries, as a general rule the clMli« 
iImhoU predominate in (he I arcer arteries and the tnuaoular elentents In 
(btmaller ■itvrii-i.x tliiU ihc I ■r>,'er arteries mav be spoken of a« eniittcntly 
abitic, or a* r«{><-<-ially uveful im accKWint of tbeir elastic proMrlic:>. and tba 
Mnaltrr artrriw n» eminently muscular, nr lu etpcciallj useful on occiiunt of 
thnr iBuw;ular pto|>t'rti<«. Tbui, in the minute arteries which are just ^uaa- 



iog into C^IUrin the niiiKiilnr i-iml, though ctiiii]inff() nfton of n single 
layer, and thst •oinclimM nn imiH'rii^ot imc, of miiiiciiliir Itbrat, in ii miicti 
Diore (^ODHpictiftiiB anil imptirtjint (mrt of thcnrlcrial wnlllhaii tlmt furniKhcd 
by th« otnxtic <■!(.■ iiK-iiu. 

The arttirw* brnmhing out fn>m n nitiglc Hurln down m niullitiidinou* 
capillarir* in murty i-vi-ry pnri of the body diminish in htire m ll»cy ilivi<)c. 
Whera un nrlvry dividt^ into two or gives olT n branch, though the bore of 
ODch division i* len thuii thiil of the am-ry Ixtfore the division or brandiiog. 
the two together nr(> grcntcr: th»t is to say, the united wclioDal area of tbe 
branehes is greater Uian the wctional area of the trunk. Henoe. tbe aec- 
lional area of the arterial bed through uhicb tbe blood Aova goa on iocrcM- 
iug frDEu tbenorla tolhecapillariee. If all the artorinl braochcv were throwa 
together into one channel, this would lorm a hollow cone with iu apex at 
the itoria and its base at the capillaries. The united sectional area of tlte 
capillnriea may be taken as several hundred times that of the tectimial area 
of tbe aorta, ho greatly duen tht.- arterial bed widen out. 

Tbe capillariee arv^ channels i>f variubk' but e:(«'ediiigly vinali utA. Tlw 
thin !>heet of cemented epithelioid |)hiti.i> which fonn.n the only irnll of a 
cnpillani' is elaitic. permitting thi^ rhannel ofli'nil by thr Miino capillary to 
dilfcr much id width at iliflt-ri-nt tiincN to widen whun hluiMl and blood* 
corpu^tclcn ar«! being pri-NX-d through it. and to narrow again wben the 
prr«8un? is loncned or cut olf. I'hc Minic thin sheet porniitt wntor and sub- 
sta»i;ps, including canes, in solution to pics through il«elf from the blt>od Lo 
the ti«ue outside the cnpillnry, nnd from tho tissue to the bliiod. and thu§ 
carries on the interchange of malcrial between the blood and the tisautt. In 
certain cireumsiance*. nl all events, white nnd even red corpuscles may also 
pass thn>ugh the wall lo the lis.sne outside. 

The minute arlerics and veins with which the capillaries are coulinuous 
allow of a similar interchange of lualerial. the more ou the smaller they are. 

The wuIIh of tbe vein* are thinner, iveuker, aud 1cm elastic than thoac of 
the arteries, and |iOH«e.-4t a very variahle aiunuiit of niuacntar tiwuc; ihcy 
oollap«(.- when the vetus am i-m|>ty. Though all veiu.H are more or lent elaMic 
uhI lonie veins ar«> ilistinrily niuncutar, thu veinii as a whole cannot, like tint 
artericVi be charactcrixed «« eminenllv elH.'>tic and conlnictile tul>v*; ihcy 
■re nlJier to Iw rcgunlcil ii;< nimplc cfiuuni'li> for couvcying lh« hkmd from 
th« capillaries to tbe heart, having just sit much ehutieily an will enable 
tfaem to aeconimoilatc ihenixelvi-ti to the ijnnnlity of blond piuning through 
Ihem, the same vein l>cing nt one lime full and distended and nl another 
time empty and shrunk, and only giflol with any i;reat amount of muscalar 
oontractility in s]>eciul cases for »]>eeiat reasons. The united sectional ari» 
of the veins, like thai of the arteries, diminishes from iho capillaries to the 
beart ; but the united sectional area of the venncavie at their junclton with 
the right auricle ia greater than, nearly twice as great as, that of tlie aorta 
at its origin. The total capacity alao of the veins is much greater tlian iJiat 
of the artcrim. Tbe veim aluue can hold the total masa of blood which iu 
life is distributed ovtr bolh nrterim and veins. Indeed, nearly the whole 
blood is cnjiahle of being received by what is merely a pirt of^ tbe venous 
iystem, vix., tbe vena porUe and iijt branches. 

The Mais Facts op thk Circulation. 

$ 113. BcJbre we attempt lo study in detail tbe Rorkitig of iheoe aeverm) 
pans of tbe mccluinism, it will bo well, even nt the ri^k of »ome Aiture repi- 
tttion, to take a very bri«f rarvi^ of tone of the nlivni pointit. 



Al tacb (mU i>f tho heart, which in miin ia ivi>piUi<<I nimut I'i liroee a 
jtoatr. ibr cotiiniolion or ctbIoIc of lh« veniricteii drives a cerlaio ijiiuntUy 
I'STblml. iMxilwblj' Binoiiniing to abmit 180 c.c. (4 lo (I ok.), wiib very ifreal 
1m iatn the aurta (awl ihe aaioe <iuanlit_v of blond willi l«w force into the 
pliniiaarjr an«ry). Tli* diKharge of blond f^om ibe ventrirfe into ihe 
HTla » trry rainil. and tlie time taiteD u|i by it a, a>) we sbatl itee, niui-h lea* 
ihiB ibr iiin« wliii-b iiit«rTen» between it and the next diMrhar^ of the next 
hat- 8n ifaat tlio Aov from iht< hesrt into lh« arteries 'u iwm dialincUy 
iMtfvkleui, •udilcrii r»{iii) discburjices alt^niating with relatively b>iig iiiler- 
nlidurinK wbtch lh<< iirU-riai receive do bUxul rnim thf heiirt. 

AlMch brai of tbv heart jiirt a» uiiii'h bloml fluux, un we ibnll aeo, from 
ib( mill inin ilkc right aiindr an OMuipc* from lliv left ventricle into Ihv 
tMta; hat, aa wc «hiU iiUo ree, thi« inHow ia mudi tlower, lukoa a longer 
tee, ihan the dbcbarg* (ram th« WDtricle. 

Wbro the finger U plncT<t on an nrten- in the living body a sense of rtsist* 
iOc» i* felt, and ihi* rv«i!>iiincc tevm* to be incrcnsed at intcn.'als, conwpond- 
ilf la the hMirt-bcata, ihv arlfr>' nt eueli hcnrt-Ix-nt being felt lo rise up or 
aatnil under the fingor, coiutituling what ne shall HtU'Iy hercuilWr aa the 
fit In cprtntn tirU'ri** this pol»e may be eG«n by the eye. When the 
fapr ia nniilsrly plaivd oti n cur ree ponding vein rery tittio reaislanoe is felt, 
mA.muU'r ordinary circunlslaDOe^ no pube can be perceived by the touch 
•r bt Ihe ^e. 

nlwa an artery is »evered, the How of blood from the proximal cut enil, 
itaM Uw heart side, ia not ciuable, but comes in jets. correepondinK to the 
iMK-beala. though the tl»w duw n<'t cenM" beiweeti ihe jela. 'llie blond U 
•MMJ mth conmderable furoe, ami may in a lurj|:<^ arlery uf a Inr^e animal 
m^mneA nut lo the di«lanc« of some fecL The lurjicer Ihe artery and the 
■mr W tbf heart, the greater the furn: with which the blood ijttiics, aiul 
ik aon narked the iiilerRiillenceof tb« flow. The flow from thp dirtnl cut 
Miihat awav frtiiu the heart, may be rcry flight, or may inko place with 
■Milrnihle turn and marked iiiKrmiltcnce, aeconling to the amount of 
alhlwal coRiniu»i(-alion. 

Wbto a CO rrcfpi Hiding vein i« aevcrod, tho flow of blood, which la chiefly 
6m tlM ilifllal cut i-nd. that in connection with the capillarim. is not jerked 
bn raDtinuous : the bloiMl coniea out with companilively little foree, and 
'•tU* up" rather thnn " »puTts oiil." The flow frwii the proximal cut end, 
ikd ta the heart Mde, may amouut to nolhtni; at all. or may t>e Hli|;ht. or 
t b* eDBfltderBliIe, depending on the preeeooe or abociice of valves and the 
Laf collateral couimunii-atiou- 
I an orlery is liuauire)! the veswl awella on the proximal side, lowanl 
Ibbovt. and the thrubbiu^- of the pulte may lie felt right up to the li^-M> 
m. On the diMal tide the veiu^l is empty and Hhrtiuk, and no pulae can 
hUt in it ohImb tlwre be free cullaleral communication. 

Wbm a rein la liffatunil the veMvl iiwellii i>n the diilul i<i<[o, away from 
tb heart, but no puuc is fell ; while ou Ihe proximal t>i<ie. toward the lieort, 
liirmptv and collaptfl unloM there h« liro free collateral riimmunicatioO. 

1 114. When the interior of an artery — fur inatancc, tho carotid — is 
in oomrauntcaliou with a long glaitt tnbe uf not Ina groat a Imre, bold 
Jly, tl>o blo«<]. immediately u|)on the oommu mention being elfeclvd, 

She Mm to rt)»b into and to fill the tulie for a certain diflance, forming 
a mlumn of hltxHl of a certain heighL The column risca not sleiwlily, 
^ by Im|», each Inp corn* |>»n< ling to a heart-ttcnt, and each leap being 
tlhoii ita prtsir«e»or: antl thta gooi* on, the incn-nso in the height of the 
Da at rui-h heart-beat each time diminiahing. until nt laitt the oulumn 



ceases tu rise aud remains fur a while at a mean level, above and below which 
it uscillatea with slight excursions at each heait-beat. 

To introduce such a tube an artery— say the carotid of a rabbit-^is Iftid bare, 
ligatured at a convenient spot. /' Fig. 6ti, and further temporarily closed a little 
distance lower down nearer the heart by a small pair of " bull dog" forceps, bd, 
or by a ligature which can be easily slipped. A longitudinal incision is now made 
in the artery between the forceps. M, and the ligature /' (only the drop or two of 
blood which happens to remain inclosed between the two being lost) ; the end of 
the tube, represented by c in the figure, is introduced into the artery and secnred 
by the ligature I. The interior of the tube is now in free communication with lie 
interior of the artery, but the latter ia by means of the forceps at present shut off 
from the heart. On removing the forceps a direct communication is at onceeitab- 
lished between the lube and the artery below ; in consequence the blood from the 
heart flows through [he artery into the tube. 

This experiment shows that the blood as it is flowing into the carotid ii 
exerting a cuDsideritble pres.''ure on the walls of the artery. At the moment 
when the forceps are removed there is nothing but the ordinary pressure of 
the atmosphere to counterba lance this pressure within the artery, and con- 
sequently a quantity of blood is pressed out into the tube ; and this goes on 
until the column of blood in the tube reache:^ such a height that its weight ii 
equal to the pressure within the artery, whereupon no more blood escapes. 
The whole column continues [o he raised a little at each heart-beat, butsinks 
a.'' much during the interval between each two beats, and thus oscillates, as 
we have said, above and below a mean level. In a rabbit this column nf 
blood will generally have the height of about !)0 cm. (■! feet) ; that is to say. 
the pressure which the blood exerts on the walls of the carotid of a rabbit is 
equal to the pressure exerted by a column of rabbit's blood 90 em, high. 
This is equal to the pressure of a column of water about 95 cm. high, and Kv 
the pressure of a column of mercury about 70 mm. high. 

If a like tuite be siniilarly introduced into a corresponding vein — say the 
Jugular vein — it will be found that the column of blood, similarly formed in 
the tube, will be a very low one, not more than a very few centimetres high.anA 
that while the level of the rolunm may vary a good deal, owing, aa we shalL 
»:c later, to the influence of the respiratory movements, there will not, as iw- 
the artery, be oscillations corresponding to the heart-beats. 

We learn, then, from this simple esiwriment, that in the carotid of tb^ 
rabbit the blood while it flows through that vessel is exerting a considerable 
mean pressure on the arterial \v;al1^, equivalent to that of a column of mer^ 
cury about Til mm. high, but that in the jugular vein the blood exerts on 
the venous wnlls a very slight mean pressure, equivalent to that of a column 
of mercury 'i or 4 mm. hifrii. We speak of this mean pressure exerted by 
the blood on the wiills of the bloi>dveBsels as blood-prensure, and we say that 
the bliM)d- pressure in the carotid of the rabbit is very high (70 mm. Hg.), 
while thai in the jugular vein is very low (only 3 or 4 mm. Hg.). 

It) the nonuiil state of things the blood flows through the carotid to the 
arterial branches beyond, and through the jugular vein toward the heart; 
the pressure excrlcfl by the blood on the artery or on the vein is a latent 
pressure on the walls of the artery and vein, respectively. In the above ex- 
])eriment the pressure measured is not exactly tbis, but the pressure exerted 
at the end of the artery (or of the vein) where the tube is attached. We 
might directly measure the lateral pressure in the carotid by somewhat 
moaifving the procedure described above. We might c<mnect the carotid 
with a tube the end of which wa-s not straight, but made in the form of a 
T-piece, and might introiiiice the T-piece in such a way that the blood 
should flow along one liuib (the vertical limb) of the T-piece from the 

ArroMM NIK iHVBRmiTUHi UiiMit'nt 

M •■ ■)(•* fteM-lwDd rmvt l« wdo, ob ■■■ tBluvBd mta. Ibc afoUil uim. *l*ai|iwt bv Ite 
M. arUkiteMcauMTMljIaaliir lUiMr, T»a •rivnr tiw b(i>ii t1palun<1 •! T •■■d IW |(UM 
r kM ■■■■• IMta)iii>*>l Iniii ihrwurir IkImmii ilir lltnilniTraii'l ilx lVi*n|aM. uHlaHwrtil 

^ ' •- t>.l1lBca aiiimlail •uluUiMi cf laUuin i«rUiBaw nr • oMUiai oT 

ma^ >( t|i, sr. lira, u»1 (■■BbtoiiT Ivlna ralaw) ur luovrrd at pliBUan*. 

naalalMu ikn> Itt iIib ii»tK p.' ncuUUd k; Ika iduup C" IMO Ite lub* l, A iiiliicc. ■Hh ■ mofr 



proximnl to the dUlul part of the cAixiiid, and at tbe »in« time by tb« oUwr 
(bonzoutal) limb nt' the T-piece iiilti th« luaiii upHj^bt part of itio gla« 
lul>e. Tlic tubulin ii)' l>Iti(icl ill tbu tube would then \>f a an-asarv t>f lh» 
pressure which thi* bhioil aa it iH llowing along thu carotid it ^-sorting on ■ 
portion of iu wuIIh correvpondiiig to the mouth oftbL- hnrizontal limb of the 
T-piece. If we wt'te to inlroduw inio tlie Hurts, Kt the pinco of origin of the 
carotid, a •imiUr (larger) T-pirn:, aiid to connect the glum lube with the 
borizdiilal limb of the T-pivn by » piece of cImiSc tubing of the nmc length 
and borv ok the carotid, llio column of blood rinng tip in the tube would be I 
the memurc of the lalenil preesnre exerted by tbe blood on the walls of the 
torta at the origin nf the carotid artery and ttnnBinitted to the rigid glafv 
tube through n certain length of elastic tubing. And. indeed, what i^H 
tnciieiireil in the experiment previously described i» not the lateral preaauJ^H 
in ibe cjirolid itself at tbe spot where the glass tube in introduced, but this ' 
lateral pret»ure of the aorta at tbe origin of the carotid modified bv tlM 
influences exerted by the length of the carotid between its origin ami Ibe 
apot where the tube is introduced. 

§ 115. Such an cxixrinient as the one deei-ribed b»A ihe diaadvantagea 
tliat tbi.> animal is tviitkt-ne'l by the loait of the bl»oiI which goe« to form the 
column in the lube, and ihut the hloiHl in ihi- tulK- noon clotv. and w> bring* 
the exjieriment to an cod. Blood-pretciure may be mure conveniently aiudicd 
by connecting the interior of the artery (or vein I with a mercury gauge or 
DUDonietcr (Pig- 06) the proximal ileiicendiiig limb of which, m, ik tilled 
above the mercury with fonic iniioeuoun fluid, ba in alto the tube connecting 
tli« manonielcr with the artery. Using such nn iniilrunicni, we should 
observe very much the Mime fnct* na in the more simple experiment, 

Imniediniely that communicnti'in i» «*tnbli!«hed between tbe interior of 
the artery and the manometer, blood ruithi')> from- the former intu the Intler. 
driving some of the meri:ury from the descending limb, m, into the n^icending 
limb, wi', and thus cauuiug the level of the mercury in the aacetidiug limb to 
rise rapidly. This ri«! is marked by jerks corresponding with the heart- 
beats. Having reaeheil a certain level, the nmrcury ceases to rise anr more. 
It doea not. however, rvmiiin ubfululely at redt, but undergoee oscilfatious; 
it kee|i.H risring and falling. Eiich nse, wbicli U very slight compared with 
the total height t<i which the mercury has risen, ha.H the i&me rhytbin aa ibe 
Ryiitole of the ventricle, similarly, each fall cornatjionclii with the diastole. 

If a float, swimming on the lop of thi! mercury in the aiicen<Iing limb of 
the manometrr, nnil bearing a brush or other marker, be brought to hfnx on 
a travelling surface, some ■'ucb tracing as that rcpreaented in Fig. 57 will be 
dcscribcil. t^vch of the smaller curvi» (p/)i corrc*|ionds to a heart-bent, 
the rise corresponding to ihc systole and the fall to liie diastole of the veu- 

eocli, BBT te iub«Uiutv4 Silt llio IwHIr unil ■lUi'lin] si r". Tlll^ iti<1>h>1, I> in uuuijr nvimil* ■ 
more tadTCDlcDi plan- Tbe mi-- ' lonnri.i'iwi uiiii ihc Iim-Ich mtit 1, iiml iw itopaDek e aUli ilw 

BunoiutUir.or U'bleb « lathi' I <. :iiilI>, bqiI tifac aiipjiart Tbv nwr- 

mrrlnlliiSMaiiillDB lliDb U'. >. :i,>^< ii>> 11 > < nxl ailaclinl in which 1* DUad 

wUbUieiicap. wraiSEoa ihc iuuMIbk •urtaucr. Tlic «I>in|.oL at the ciul al tbt tubal bM «n 
enaiifanwtn ahoua oti » lar^nr waloul the rliilii hand miliar cunier. 

n«4anMvlla|luto not (ho inauciindat Hill] ihg mbalboing nmuplalal}' Hlled tiimit It* irbela 
lanfUl Wllb fluid to ibe exoliulmi of all air, thn mnuta « la ail«d wlih ftuld, (llppeil lula Ibo opoa 
mi ot Iha thick -vallfil Iiiitia-njIiUt lube i. unUl It mtou tbe tubs ( (wboaa poritko wnblu tlia 
iDdla-nblsr (iilw U ikown hr the itiillnl llnnV and 1* Ibaii •viTimlj' Dxsd In Itila p«alllni by iIm 

Tbt •idpi'Mkir t aud f* an anr npcoM. aad the proauni bniilc talHil or (luld drfTOD Is bjr U» 
tritniir until Ihe mcreaiy tn lb« uunoncMir t> ralMd in lh« iVi]iilmI belglit The rlamp r" Ii then 
Blnatd aiut tin loreeia M nuioml Irani the adefT- T^ pmaan: ur Ebc XiioeA in Ibe earottd m U 
' la eonsqiMne* Iinuijbi lu I've lhn-<U(h ( u[idii tb* nieiriir) lii llie maoomvter, 




trid*. Tlitf' laripir iiodulttions (r r) in the tracing, irhioh are retipirntor; 
In origia. will M dbciiastd h«n>«ller. In Fig. oH are given tiro tnciu^pR 

1^ X, 

nt^Hlto ovm* )• V arv U>r rolawiiTC*. Tti*i|«M IKnn r (n r vmbmi'ca n rcrfdntiay and*- 
M« 1Wln<ilai9>ukiiqnvB»dcc.B<>4U>B lrn«uliulll«TWIiialiittucUKiwrn>|iM(illr M«l 

nha fromltbe rarotid of a rabbit ; in ili« lower curve the reci>nliiig mirfiire 
iiinndlia^ inon; rapidlv lliuii iii tlie umier rurve: utbemi«e iliv curves iire 
ittaMd repeat the Jteneral f«tur«t of Ui« curve from tlie dog. 

no. M. 


liiflnnrKBmiac Cnrai meat rai C^ion* or B>MfT. nix lau "*■"* 
in uo HUM Uittom Bbcdsm. 

fl—yltw ^ rxfirriHtrnt. In a CHrotiil. or other bloodvMM], |iroparti] at ex* 
(UmJ, ■ Rdnall RIM* lube, of »utUbU- liori'. called a amata a introduced by Ibe 
Brihod tleaoitied atiove. Aiid ia suliw<]UFDtly ouniiecled, by eacaos of a aliorl 
rwoaf India rubber tubing { Figi. M >), aikI s Iciulfn or other lube < which U al 
«n^lrlllil« and yet ool exiciuihic. willi lhi> i)nii-en<lins Itnih. m. of ihc nuuin- 
«M<crot mtrcury cauiir. The cnnulit, (ubr. anil <ltiici.-ii<liii); limb of the nianu* 
twan all filled with toine fluid, which tenil* lu {irrtent clotting of the hlood, 
innc chnaen bpinK generally a atroiig tolutloii («[». ^r, |i>S3) of aoiliiim bicar- 
•, Uii other Hums oiaj ha cbo««n. In order to avoid Iom of blooil. a quao- 
' flulil i* iiijrtMd into ibe flexible tube auffieient lo nuBO tbe morcory in the 
( limb of the manometer to a 1»vf1 a rery little Iwlow irhni niny be 
■d gn«Mtd at iw the irnibabic meiiii [ircMure. When llie (oref|M M are 

h\, the prMHire of Ibe bl'iod in tbe carotid in irannniiiied Ihrougb Ihr 

luiUr tnW u> the muioBieter, the lrv«l of the mercury iii the lucciKliiie limb 
«f ehkh falU a little, oraioks a lillle al finil, or uiay du iivilher, aecorJing lu 
lb MkfTvM «iib nhieh itic prubable riivaii prrwaiire hnn been guooied. anil on- 
llnai In eihiblt tbe chiraetetinllc oM-ilUll'init until thu experiment U brought to 

u ml by iba Miioil ilotiinx or otbnririM;. 
ITneli^p of the im<iv«<ii 

_ . ^ iiv«<incnli of ibe oitumn of mercury in tbe manometer may 

wukra riihmm a mnohed surface of a revolving cylinder (Fig. )l>. or by m«anii 
«f abnuh and lok on a oiniinuoui roll of tiaper, aa in the more C"ai|ilcx kvaiO' 



S 116. B^ iht help at Uio taanAtuot«r a])pl!«d to various art«r»eei ntid vt 
vn iMrn Uic folluwiuic tiu-i^: 

1. Till' iiii-uii 1>lii<iil-['ri'!«<iinr la liigli iu ull tlie arit-rioi, tiui i* greater in 
llic lurgiT nrtcrit^ iiritrcr llii? h^-nrl tlinri in lli« miiEillur urieries I'lirthi-r tfum 
the hmirt: il iliuiiiii.-'liot, ill fnci, ulong the urterinl Lnicl frutn ihe liuirt 
l»vriiKl (Iu- (-ii|>illnrii-9'. 

'J. Till- nicnn Wniid jircMuru id luw in lln- *'dii» but, io grrali-r in tin' 
emalkr leina near<-r lh(> iiipilliiric* tliun in llic Inrgvr vi-i:i» imrtr ttir UiMtt, 
diniioishing. in fiicL, Oom the i-apillariof lowiirvl (he Iiviiri. 1» tliu largo 
veins near tlic heart it may bo ifj-ilix-r. thai i* to rny. the pri'S^ure ol' hlmti 
ID the vein bcarini^ on the proximal dctudiiJitig limb of the ninnomclcr ma]r 
be leas llinn the pr^MUrc of tb<< alnio^phtrc uii ihi' sHCfiiidinc iliital limb, eo 
that when coiuniiinication in nindo Wwccd ihe inieriur of tna vein and the 
wunomeler, the nterivtiry lunkt in lh« distal and rises in tbe proaiiual limb, 
being nuk.'ked tip Mwanl the vein. 



■--a ■ 

tjCDWM't XvaooRirii roa kaamnjiu tin a CViNTtvunis Kou. up I'atu. 

Thti tnanomctor cannot well bv apniied ui the capillarioa, but wo maT 
ipcamirc tbe bloml-premtirv in the cnpilhine« in an imlirbct war. It is well 
knnn-n that when any portion of the skin in prerned upon, it becoin« pal« 
and bloodless ; tiiio is due to the preasiire driving the bliHjd out of the ca]>il- 
lariea and miautc veawls and prevenliu); niiy frtvh blimd t^ntcrtng into lb«D). 
By earvrtilly inveetiicittiog the iimouni of prtmnre mxiitfiiry to prevent tb« 
bli^xl eiili^riiiK ll>^ eapillarii« and miniii<< nrt^riux of |h<< nt-b of tbe frog'a 
foot, or of (he nkin bi>uvulh the oail itrelMwhcrv in nmn. the iuternnl pr<«- 
Hire which thtt hbHHl id exerciiiiug on tht? walla of lh« capillariea and minute 



■llfja awl v«itu mav be Rpproxiinaiclr <l«termiaoiJ. In the froR's web 
bMD fuuiid to lie e(|iiul to about 7 or 11 mm. of merciiry. lo tlie 
tb* capillarT liltKxI-gtre&tui^ n naturally higher lliaii thi* aiid maj 
!•( ilowa at fruin 'JO to ^U rtini. It is. tlieivforv, c»»»i(l«mble, beiiiK 
ptawr llian thm iii lliv vvmn lUonKh \tf» itian lliai iu ihe Brl«ri«a^ 

JL Tliprp bi llius K oniiiiitiifl di-cliuL' of bliiiMi-pn-BMire Trnm tlie nxil of 
tk aurla. llinxigli thv arli^ncii. t'lijiilliirirs, hdiI vi-iti.-t Iu lliv tigltX aiirirl«. 
Vrfiod, bi>«rvrr, iiii I'xiiniiniiiinii tliiil tbe mint nmrkt^l Inll of [iritc^nre 
lU* |>la<v bi-t<iti.-rti tin- kiiihII ntte rim un lUu utiv xiilir of the nipilliiruv am) 
Ibtwiall t*riiu OD iIm> ntlier, iIm' i-iirvo iif {imviin- IkJiij; itomcwliril of tiie 
tm given ill Pig. t>0, wlik'li » >iiii{>ly iiK^nilftl li> tlmw thw fact gnii>liinilly 
mi bat nM bMO ranMriirtei) by exact ni«ii»iin-miiiU>. 

Fill. cu. 

I'MOIUI* or niJUnlVPBBMtTlta. 

/*. tcH|iliemln4tealmliiiili(Knnte*.<w|il1lrulei.aD4 vdai); V.Miu. 

i In tW art«Ti» thk meuo pmaure b niarked by oadllations cam- 
In tbe tienrt beats, each wcillatiou coosMtiiiii; of a riwe (iDcrease of 
in abote tlie nictm) eorratpondiiiK to Ibe systole of tlie veiitriol«. 
by a Call (dfcreaaeof prctwire below tlie moan) eorRS{ionding tu 

idiMtoM of the vvutricle. 
Vum owdllatioDH. nhkb yn may .-jirak nf iia the pulse, an- lurgcvt and 
■M CM^iinwua ill the l«rg« arteric* iK-iir lliu lioiirt. dimiiiiiih fnni (ho heart 
Wiwd ibt capillarioi, niid iire, iiiiik-r uriliniiry (lircuiimtuiii-'uii, vrholty hIumiI 
fha iba Ttina alnng tbcir nbolc exirut frvim the mpillnrim lo tlii^ hcnrt, 

ObriDualy a ^rvat obangv Iaki9 pliin- in tlint piirliim nf thr i-irviiliitioti 
vUdloamprion the mpillariiv, the iiiiuiiU^ arli-rii-n li-iidin)i; to am) ihc minuto 
*tJH laadmg away from llio capilliirii.^, luid nhich w- miiy apvak of n» the 
'pwiplmsl rf^on.*' It is hen- that n great drop of pmviiro tnkM plaec ; it 
iikftalwi that thr p^ilse diMpmare. 

|UT. If lite neb of n lixiga fixit be ciaminni with a tnicnwcope. the 
bliul, aa jiidgt*! of hy the nwvemvnts of the corpuBclcs, is sevii to be pnssin),' 
in a DuotuiuiMis rtn-iim from the small arteries through the ea[^llaries to the 
im». The vidoeity is giealcr in tlie arteries iIibii in the vv'im, and greater 
ii belli llian in tlie capinnries. In the nrleries fuiut puliuitiunB. ^ynehronoDS 
ailk iba heart's bent, nre freipiently visible ; b4it these dirapjtenr in tliv 
■nillariea, in whtvh Ihe llow is even, that it, not brokeo by piilsalioRs. and 
t^ iTeDDceB of flow is continued ou alon;t the veins as far as we enn irnco 
iImo. Nut infre<(ueiitlT vnriiilii>n-i in velocity and io the distribution of 
lb*h|nud, due tocauM* whieh will l>e hereafter ilit«uai«d. are witiwBsed from 
liawif) liine. 


The chRraclcr of fho tlow ihmugh the smaller cspillnrira is wry Tmriabl«. 
8oiiietiin«« the curpiiecW nre seen prntsint; through the i-hnnii«l in siDf^le 6k 
with great ref^iilariiy; nl riiher liiues ttiey inar be lew luid far betn'e«ti. 
twnie uf the capilliiric^, as we li&ve said in ^ 107, are wide eai>u]{b to permil 
two or more carpiiBcle« abreaat. lu k1) caaee llie blnod aa it paasos ihrou;^ 
ttie cspillary Airetcbea and ex|)iiii<!s the walla. Sunieiimcv a corpuscle uuiy 
remain aiaiiuiiary at Ihe eiiirHiice itilo a i-a|iillartr, ihe chauoel itself botng 
for some little distance enlirt-ly live frcnn Gur|iuioles. Saraetime* many 
corputteJes will appear to rvmaiu uratiuuary in one or mon vapillaric* for ■ 
brief period aud then in niiive oa uKaiii. Any one of ihettc coitililioiu 
readily \vtMti inlo iinulher; and, cii|>i.'cially with a aamewhat feeble cireula- 
tiim, itialniii'CAof all of them may )ie«eeR in the name lli^ld of tbe niicrniH'opc. 
It in only «lii-ii tbe vt^itN.'li' of the w<:b arc uHumially full i>f hUiod that all 
the cniiillnriw r-an he «cn vaiinlly filled with corpuscle:!. Tbo long, oval rod 
ourpu»cle inovra wJlli iv long axis parallel to ihc stream, oceaeionnlly 
mUttin/^Dii iu lung axis, niid ■i>inrl!me«, in the ]nr;gcr channels, on ir^ short 
axis. The flcxibilily and rlnxtiiiiy of a Rorpusclo are well seen when it » 
being driven into a capillary narrower thtin itself, or wben it bccomva tetn- 
pornrily lodged al the angle between two diverging channels. 

Thno ana ntber phenomena, on which we »tiall dwell Inter on, may lie 
readily seen in the web of the fn>g's foot or in ihe stretched -out tongue or in 
the niewntery of the frog; sad e»entially similar phenomena may be 
observed in the mesentery or other transparent tissue of » msmmal. All 
over the body, wherever eapillaries are present, the corpuscles and tbe 
plauna are being driven in a eonlinuous and llinugh somewhat irregular yet 
on the whide Meady flow ihron^h channels so minute that tbe poasage U 
maniftBtly attended with cousiderable dilUculliea. 

It is obviouH that the peculiar ebaracien of Ihe flnw through Ihe minute 
arl^irie*, capillnriia, and veinn affonL* an explanation of the ffieat change 
taking place in thi- |icri|iheni] rt^ginn between lh« arterial flow and the 
venous fluw. The muted Mretinnal area of tin* capillaritv tt, n.* we have seen, 
BOiDO faundrvils of times grvnier than the sectinnul tin-a of the aorta; but 
this nnic<^il wclionnl area is nindc tip of thousandH of minute piuwigca, 
varying in mmi fnim ■> U> '.'(I u. some ot them, tlien-fore. being in an undis- 
leaded condition, smaller than the diameter of a red c(jr[Hiscle, Kven were 
tiw blood a simple liquid free from all eorpiiccles. ihcw extremely miniile 
piWUflfii would occn«i(iu an enormous amount of friction, anil thus present a 
oontaderable o!>stacle or rvaiatttuee to the How of blood through ibom. StjII 
greater must be tbe friction and reftisinuce oceasiontu) by tbe ncliial blood 
with its Tvd and white corpuscles. The blood in fact meets with great difG- 
eultiee in its pasan^'e through ihe peripheral region, and somelinies, aa we 
ahall aee, the Iriciiou aii<l resistance are so great in the peripheral reoaela of 
ihia or that area ttial no bJmid pa^tiea through them at all, and an amat of 
tlie Jitiw lakes place iu the nrea. 

Tbe nwiHtauce t<> the (l><w of bloud thus caused by the friction f^uerated 
in Ml many minute pawagen i» one of the moet important ph_\-sioal fiuita in tbe 
drculation. In the large art«rie« the friction is small ; it increases gradually 
M tbcy dividi', but nn-rivM iu chief and most imporluut addition in the 
minute art<iriv» ttn<l mpillnriv*, it ix relatively greati-r in the minute arteries 
than in the ciipilliirii-* nn accoiinl of tin- IIdw being more rapiil iu the fnrmer, 
for friciinn diniinii>h<« riipidty with a iliminiilion iu the rale of tlow. We 
may speak "f it as tbe " i>eri[iheral Irietion," and the roixtancu which it 
oflersus Ihe "|>eripheral resiniance." It need perhaps hanlly W mid that 
this pheripheral resistance not only op|Hisc» the flow of blood Uirough the 
c*|^Iartue and minute arteries thonisvlves where it is generated, but, working 

THE Mais wxcra of tok cibcdj-atjos. 


■ckvard Rlvng the whole irurial iyittftin, has to b« uveroome by th« h«irt 
1 «acli ■jraloJv of Ui« ventricle. 

JlgdraHlie Priaeiplr* of fh^ CirttutntloH. 

8. In ifav drrulntinii, th«n. ihc fotlowing* three Gictx of fuDdnnwital 
taiiM MTt net wiib : 

Ttw >jr*iuJe n( the vcDlricIc, driving at intervals a certnin tjuaDtilr of 
Uood. with K eortaiii foixw, into the tiorUi. 
3. Tb»|Mripbnal rtsistance just detcribed. 

S. A km; MnKch of elastic tubing (the arleriee>, reaching from the 

to tlu! region of peripheral resisuiDC«. 

<m tfanc fnds wo titaj explain the main phenomena of the circulatiou, 

Aith «« have previously sketched, on purely physical piiadpl«s without 

U<r arptal to the »{)ecial pn>perti«a of liviuK tiasuis, beyood the provisioD 

Uai tKr veoirirle remains c»]>aDle of (pMvd rhythmical con tractions, that lh« 

■fkrial walls retain tlieir elasticity, and that the friciiou betwoeu the blood 

u4 Ih* lininj; of the peripheral vessels remains tlie same ; nc niuy thus 

nyUo the htgb prasurc and pulsatile flow iu the arteries, the steatly streuin 

luMffb tbe capillarM«, the low presanre and the unilnrm pulscltMS lloir in 

(bniBa. aod nnally the continued flow of the blood tVom the aorta to lh< 

moiIm air the vean cavir. 

AH ibe atHive phenonH-na in fart are the simple nviiItM nf iin iiitrrnillteot 
firw(lilte that uf the sys't'Lilc of the vrjilricle) working in a cl<.iM-d circuit 
*f Ismching tulMs, wi iirningul that while the iudiviHiiiil tubes lirel 
^iamili in calibre (fmni ihr heart to the cnpillnrie*) anil then incrvusc 
Am (h« capillarifv td the hrurt). the area of the bed lint increoHw and 
Wi dimtnishts. tlie tubes to;^iher thus forminf; two conee placed base to 
it the capillaries, wilh their apic.'cs converging to the heart, aud pro- 
at their conjointed bases a conspicuous peripheral reaistaiifv, tlio 
cm one side, the arterial, bdtig eminently eluittic, and on the other, lh« 
, affiwdioff a (tee aud easy panage for the blood. It is the peripheral 
aae ({or tbe reaistaoee oftVred by the friction in the larner vmmIs may, 
•hso nniDared with this, be practically ueglecl«d), reacting through tlie 
•Wc walls of the arteriea upun tlie intermtlteut force of the hiuirt, which 
pirn the drculatiou of the blood its t)cculiar fcaturu. 

iU9. Virtumtlatuet ilftirmmiuQ Ihr. charaeirr of lAe fiow. When fluid 
k dfivfO t>r an iDiermittent force, as by n piinip, through a [lerrnctly rigid 
M^ soeh aa n glnas one for a fy*t«m of xuch lulim), there nu-apvs at eavb 
mb of the pump from the di*tal end of tbi.' tube (nr .ivi>lem of 1u1m») just 
■ ■aeh fluid AH cutirt it at the proxiiiinl end. What bnpiiciM is very like 
ah* woald hapjien if, wilh a wide glsn tube completely Bllixl wilh biliinrd- 
Uls lying in a row. an additional bail were puabcd in nt one end ; each 
hsD would )ir p(i»li<Hl on in turn a tl»fp further and the last ball at the 
hither end «i>uhl tumble ont. The eacape, morvovor, takes place at the 
—«» lime «a the entrance. 

Ihi* rcanlt remains the §anie when any resistance to tbe flow is introduoed 
Mo the tube, as for instance when the end of the tiit)e is n.irrowed- ThA 
: of the pump remaining >he same, the introduction of the resistauoe 
•btedly Icawns tlie ijiiantity of fluid issuing al the distal end at each 
s, Imt it at the same time let*«iis tbe quantity entering at tbe proximal 
lh« iolluw and outflow remain cijual to each other, and slill occur at 
saw time. 
la an alattic tube, such as an India-ratiher one (or in a system of suoh 
nW). whose aectional area is suflirientiv great to oJler but little reuatanoe 

13 " 


Ik iIh- |>rogr«M of ihe iluul, the flour ciiused br an iDtermiUeal force b rIw 
inli'rnuttcut. The outfluw beJOK uearly as t-oAv as the ioSow, tlie elulidlf 
of till- \>flllii (>r thf tuW i> H-anvlv iit «)l talletl inio (lUy. The Lube behant 

SnctH'til))' Itk).' H rigi<l iuIk'. \Vbi;ii, h»w«ver, auliickiit rmMaDce u intn- 
ucc<l into liny iitirl of tke voiinto, the lltiiil being unnbte to pnat by ibt 
mwlancv m ntfHmr ni> it eautn tJw tube fmn) i}i« |iunii>, lenilfl to acminiiliie 
on thi> nroxiniiil inilo of iIhi nxiialaiu'iv Thi* it u Able to ilu by ex[i<in(lia( 
tbeeinstic wuli* of tbitliibv. Atuivh Mrukoof the fHimp n vertnin ()iuuil)l}' 
of fluid ctitcn' tli« tube at l)ie pruxiuwl cud. Of iImh only n fV«<-lioa cu 
pBA tJirough t)i« reMctiincc duriag the »troli«. At ttic iw>m«ni whw thi 
Mrokc CM8W, th« rait »til) nrmainM on (he |ir(>xinuii aide til' the nvislUM, 
tlK elastic tube having «xpaud«d to reoeivi; it. During tb« inivrAiil bvlwwa 
tiiia and the next Rtroke, um dietendnl elanlic lulxi, Hnviag to rrtum in !tt 
natural tuidulanded condition, prcnn on lhi» extra ({uanttty of Huid whidi 
il coiitaina and tends to driro it past tlie mistnncw. 

Thiia. in lh« rigid lube (and in the oln^tic tube withotil the reoitaocf) 
tliere ie«iic&. f'runi the diolal end of iho tube at each stroke, just as nnifa 
fluid as eniere it at the proximal end, while between the strokes then !■ 
perftet (juiet. In tha elaslic lube with reustiuice, on the ountrari-. the qiuu- 
titr wHioh jMxto the renalaace is only a I'rauiiou of thai which euienilit 
tiilte fnun the pump at anyone stroke, the remainder or a portion of tlw 
reinnindcr <'(mtiuiii»K l*> [>sm durinjt thv iuler^'al between the strokes. U 
Uut fonuer ruav. Llie tube u uo fuller at the end of the stroke than at tW 
b^innin)! ; in the latter caae there in an necuniulation of fluid between ibe 
pomp and the nsiHtuum, and a eorreiipmditi}; distension nf thai part of ibe 
tube at the rtiBC of earh »lriikt! — an nci'timiilatiun and dislciiBtitu, liowever< 
which 20 on diniiniohiiie during ihir iiitcrvul hrtwevn that Mtriike and tb^ 
next. The nniminl nf fluid ihiiii remaiuin); ufter the Htruke will depend uO 
tke amount of n-»i»Ca»pe in rclnliim In ili<; force of the sLroko mm on ll>* 
tliateiuiibility of thit luhr ; and cbr amount which jiaflMM tbo mistance Wnr^ 
the next rtroke will ilcpviiit on the drgriv of elnstJc rottction of which tl»* 
tube is capable. Thus, if l)i« miRtnnco be very iiinsiderabic in relation t^ 
the force of ihu rtrokc. and the tul>e vtrry di«tcn«iblc, o«ly a »miiil n>nioav' 
die Saul will [lOW the rc«i«(iu)ce. the gn-nier [Hirt remaining lodge*! betwve** 
the pumn and the rwaistanoe. If the elastic roactioii be grent, a larife po^' 
tiun of Ihis will be pmed on through the mistanoe before the next stroke 
conies. In uther wunU. the greater tbe resistance (in relation to the for^ 
of the stroke^, and the more the elastic force ia brought into play, the lei^ 
iulermittent, the more nearly continuous, will be tbe Bow on Ihe far side<» 
tke resistance. 

If Ihe first stroke be succee<led by a second stroke before its tpiautity of 
fluid has all passed by the resistance, there will be an ailditioual accumula' 
tion of fluid uD the near side of the resistance, an adililJonat dbteurion of 
tbe tube, an ad<Utional strain on its elastic powers, and, in con*er]iieiice, tbtr 
flow hetneen this second stroke and llie tfaini will be even niont miirki-d thUL 
that b«iweeu tbe first and second, though all three strnkcM rn-ri' of ilw sani* 
fom, the addition being due to the extra aiuouiit of diuttic (•<nx called int» 
plav. In fact, it u> PviiH-nt ihut, if then.- 1h' a sufficient store iif eliu^ic power 
to lall back u|>uu. by i^oniinually repealing the strokea a state of thin|f< will 
be at la*t arnvwl ut in which ifie plastic force, callc*) into play by the coa- 
dnually tncn-iuiiug dinicnxiou oi' ilxi tube on tlie near side m trie reeiuanoe* 
will befuRicii'iit l<> drive thnnigh llie raualauoe, between each two siroksa* 
jtlst a» much fluid iw cnlcm the nirar end of the syalem al eneh stroke. Ik* 
olber words, the elastic renclioii of ilu- wnlU of tlie tulx; will ha?e OODVMtcA 
the iut«riQitt«iit uuo a ooutinuMia How. Tbe flow on the br aide c 


IM [« in lh!s <-«M not tlie •/!>«¥< reeull of the strokes of i)iv ]iuii]|>. All 
v» nf ihc pump ie epenl. 6ret iu getting up, and afterward iii keopiiij; 
i^ tlio ilieleo^ion of the Uibe on the near eide of tl>G resistance; (ho immft- 
Kte caiiac of the coDtiououa How lies in the disteiiMon of the tul)c nhiob 
his it to eoipt}' itself into the far side i>f the resistonee at suob a rui« that 
dtschar][«8 tlimuifh the rrais(aii<-e dnriii^ a stroke and in th<! viiccecding 
l«ri kI Just la luucti as it recirivui frum (he pump liy thi? ilrokc itiitlf. 
Hiis id exactly uhat Inkm plm-^ in the viiscuiur avfllein. The friction iu 
p minuie artc-ritv and ciipillntie* pr<4eiil)i a coiini<MrruliI(! rexuilaiiw to the 
f/n of hloiHl through ijieni iiito thi* Kiunll veins. Iu coni«-r|uence of tliis 
UatMice the ibroe of thr ht-iirt')! heiit m «pMit in niiiintainiiig the whoU of 
te arla^rial pyoiem in a ilntv of grent di>Et'n>i>in ; ihr nrlerinl wiillii are put 
t^Mif iiu tli« Htretch br tbe preHura of ihi.^ hliiuil thrust into (1r-iii bv the 
t|ar«trd olroko of the heart ; this U (lie prtroiiro wliich wo Bpuko of above 
I bluHl-pnwiiire. The ureatly dii^leudtd iirtrriul qretcm in. br the elastic 
MolKMi of lis elastic walls, eontiuually lending lo rmptv itself by uvertlow- 
p% ikmuf^h the capillnrtes into the venous svMt'ni ; and it ovcrtlows »t such 
tnUi ihni juBl ne much titoixl i>aai«s from the nrteries to the veii)» durlug 
Mi ajstole and iia sucL-eediug diastole as enters the aorta at each sfelole. 



Aatnu*t Sirnm. 
— „il. ball clMI'* inlxtn n(«tMiil ih* trtmal •jitem, bnuicblni*! X nii'l V. and (ndlns 
*kn^ninr |i<Tl|>lwnl mMtaim. lacli>llnii(hocai>lllkrl«^(rblchBi«iinlutol br olUav IoomIt 
'*'^IMU jtvm bI tpiinc* i*» |«ru iiliaoii u dilated tn llie ngmr. Tlw ea|4UiiTlgi air galliond 
*'MUi tmim (j-tiiB. ibiulol. H'hKb icnnlnaWaatU. WaMr I* drlrtn into the anntal vj»\ma 
I'T** "" '■ er ail i-laMt* fe*|t<yrii>«D <» anr o(hcT ream drpimpi, C1aliiiaB» ptu«<J on Ibn iindl' 
"'''Mar, (•, p". W'li(-n llivw Dlani[atanll«lili-iird, Uiruiljr accaa Ibaltir aatiir it'Oa ttiaanarlat 
'"'•••■aBMitalalliR'iialinii;4IMrd parla niird wini iirODg*, whif h e An a raiuldanbt* nitat' 
^*<killO*ar I<ildUm<ti|ibtbaln. Wtttn Ib( plDin|danDlilaaK<! HtcHiild pwaca. lalUi OMtcfa 
"■MtNutra^ Hiimifh ilio iindllaHd litbM> Tliiu. Iiy ll|[hltaIuK or louMitii( lh« elamt* tba 
'"Mmt' naliiaiun mtf In Intrt— <l or dIjnIoMml M jjwjnw. 

'**.<• llMtfiariai -hie. aiKiai V. oa iho nnon* ilitc, iMiwanetcncan be altaobed. Aiatnd* 
^■Mtt I «iid f I, bj nmiiii or riaini*. Itw nuir i>r dald ttt^ an ait^vy add team a vidn, ondar 
"^tcMIBwk awr l« «t«tnO. M fa. fa. and t^r. t|ih]iiiia«n|ibi may be appBtd. 

IIMI, ladeeil, the tniportant Incls of tbe circuliitioii which we have not iu> 
T*i i>udtti) may In roughly bm Hicccwfully iroitnled on an nrlificial model. 

Fig. 61, ill whioli an elastic syringe reprefieoCs ibe heart, a'loii(f pi«v 
dasiic liidia-rubWr tubing the arteries, anoilier pie<.-e uf Iiibin;^ ttie veins, 
and a number of Hiuallcr (.-ounecting pieces the minute arteries and onpil- 
lari«e. If these connecting {liecea be uutde at Ant aomcwlint wide, so sa to 
oSer no great resistance ti< ihc tluw tVuin the artitidal nrlerii^ to the artificial 
vdns, but Iw eo arranged that thev maj be made narrow by the .tcrewiuK -up 
of clainporotherwiiic, it i^ pouibli; tti illuHtrutc the behavior of the vascular 
luechamain wben iJie i>eripliural resiAtancL- in lt«s ttinii umiul (and &• vv »)iall 
•e« later on it is poMible in the living organism either to reduce or to iiicrcajc 
wtiat tnay be considered as the norinnl jieriplieral nwiAiancft), and to conijwre 
that behavior with the WhMvior uf the inecbaiiium wbon the pt-riphcral 
n«i«tauce ia iucreaMd. 

TIh! wliole apparatUK being placed Bat on n table.KO as to avoid dilTerenocs 
in level in dillerc.nt parta of it, and with water, but so ns not to distviid the 
tubing, the iwa iniui<>inet«ra attached, one (A) to the arterial si<lv of the 
tubing and the other (V) to the vchoub side, ought to show the mercury 
■landing at eipinl heights in both Mmlw of both iu^irumcnls, since nuthiae 
but the pressure of the atmosphere is bearing on the fluid in the tubes, ana 
tat equally 

that equally all o\'er. 

J pieces b 
reaistiince being verv little, we imitate a ventricular beat by ihi? stroke of the 

he conni'cting pieces being fn>oly open, that is to say, the peripheral 

pump, we aliall observt: the following : Almost inimediatefy after the stroke 
the ntercury in the arterial manometer will rise, but will at once fall again, 
and very shortly afterward the mercury in the venous tube will in a similar 
loaiuier rise and fall. If we repeal the? stnikes with a ni>i too rapid rhythm, 
eaoh stroke having the same furoe, and make, h^ may by a iiimple contrivance 
be eflevted. the two manometers write du the Katue i«coi-diug surface, ne shall 
obtuu curves like those of Fig. 62, A and V. At each utroke of the pump 

no. an 

TaAOirai T*SB( PMM AR Annnnii. 9rniuni, with rax FKHiruniAi KnoBrunx Suuur. 
A,ut«U: V. Tvuoui nuiunnoler- TlitiOiiure, ui wntiocc, !• m t ■nullwMSle Ikan tboror- 

n«poiidina r%. <y. 

the mercury in the arterial manoineten riaet, but forthwith fnllt again to or 
nearly to tlto l>a»o line; no mean arterial prcMum, or very litth^ in •■tabliibcd, 
The cionieoi* of the ventricle ("yringiO thrown into the arterial »v*t*tm dis- 
bsnd it, but the jiMmgo through the jieriphcml region is no free that an cQiial 
quantity of fluid pas*v« through to the veins inimedintelv. and hence the 
iDorcurv nl once falls. But the fluid thux pnxfing casilv into the veins dis* 
taoda tteao too, and the mercury in th<nr manometer rfsce too. but only to 
&U Bguii, as a corresponding quantity i^ines from the ends of the veins into 
tbe basio. which »ervo!i as an artilicial auricle. Now introduce " peripheral 
fesMtonoo" by screwing up the clamps on the connecting tubes, and set tbe 


^■i[>to «Drk again u bcfure. With Uw liret vtroko th« nwrmry in tbe 
wuwil Mnowrttw (Fig. 68. A') riw ks before, but inHeadaffiUUiiff rapidly 
t bSk alowlf. becBiiw it now uk«a ■ longer (imfi for a quantity of flui^ 
iqMl ta thai wliidi hns Wn thrun into th« arterial snum or tl)i> veutrica- 
«^i«ka Id |HUa llirt>ii)(li the narroireiJ |icri|ili«ra) region. Defore ibe mirre 



twaw T<as9 raoH ui AimnatL Scmc, wim nrx PranmiL tUMmuta OmnKiuHa. 
A'. HMrlal ; V>, nnoaa iia mill nil 

bwUIni til tbr baw lin«. boforo the arterial i^vtem has had lime to dia- 

thai]gc lhniu)[b ibi- narnivroil iH<ri[ib?ml rpgioa aa roitoh lluii) as it receinjd 

I^M tha TTOtrirl)', a woiiii) Ktrukv <lnvr» more fluid into the urterieA, dis- 

Mtfiac ibrm tbi* limi- inori* ihnn it ilid before, aiul raitiiiijt lite luereury to 

a ffill ht);h«-r l«Vfl. A thini, a foiirtli. itnd suoeeeding Mriike- ginxiuce tbe 

■airrflcrt, cxcejit tliHt tbe tulililionul Jveigfat to which tbe uifreurv h roitHHl 

•t taeb (trc^v becomes at each 'trxke le«s and )i?s8, uulii a ntatv i>f Iblii)^ is 

nocfctd ill whieb the mercury, briof; uu the fnll wbei) ibe ntruke lalcvn {>[ac«, 

ft bf tb« Mnike raiMii juHt as bi);b as it wa« before, and tlieii )i«f(intiiuj; to 

Ua|P^ is aicaiu raised just as bi^cb, and so nil. Witb i.-Ath siii'c«<diiig 

Mnlw the arterial ByUem has becooK mure and Riom dixleixleil ; but the 

■en ilisiMKled it is the Kreaier ia tbe elastic reutriiun brougbt iuto play : this 

flMcr clastic lettctinn more aiid mora overcoaKS tbe obstacle proaoDt«() by 

la* fcHpbrral mietance and driv» the fluid more and inoro rapidly tbrouKii 

tht i«npberal refcion. At laMt tb« iirtcrial systam !■ so distandoo, aiid tLe 

faftc of llie elastie rcmotioii Mt ffreal, tbat durinc the sirokv and tbe sucoeeil* 

m( iaurval just ua mucli fluid ]>aNN,x> ibraugh tbe peripliemi r^^ion M oiitara 

tb> ■ftJ'rtm Mt (he ■ln>kir. In ntlier vrimls, the rcpratt^l ttruk'* have catab- 

bbtd a menu anrrinl iirawiire which, lit ibc |H>itil where the mnnometor 

ii sAsad, is raised sligtilly at eneb vMitneular Hroku and falls slightly 

b<t«m 1^ strokes. 

Iteaiag now u> tbe vcn<Mis maiKviocter, Fig. 6S V ', w» observe ibiu each 



Ctmlcc nf the pump [>^}<iLlcca on itiin much less ofTort than it dit) Iwfon L_ 
intriKluclioii of the iiicrcuwd ])criphcml raeiitAnce. The iiiercurr. inntewl^ 
diftinoUy rising aiwl faUiDg at ench Htroke. now shows nothing more th>n 
v«rv gentle uuduUtions ; it fe«lB to n very slight degree onlr the dirf^i plfe<4 
of the ventricular stroke; it ia simply raised slightly nbore the base line, 
and rcmitinB lairly steady at this level. Tlie sli;;!it riae marks the nieMl 
prenare exerted by the fluid at the place of attaclioient of the manometer. 
This tDefln " venous " protHure ia a continuation ul' the mean arterial preeuure 
BO obvious in the arterial nmnonaeter, but a much leu tlian that because a 
large part nf the arterial mean pressure has been exi>eiideil in driving the 
fluid past the periphera! reeistant-e. What reiuatDx i*. hciw«ver, ttultideiit to 
drive the fluid aloiiji; the wide venous tubing; ri^ht t<> llie upcn end. 

Tliud ihii aritfifial niiidcl may be made to illuntrat*! liovr il comi:* about 
that ibe bli)iii] ttiivi* in the artdrie* at a nOativrly high pn^3t«ure. which at 
aach ventrioulnr )>yst<d« in mi»ed (lightly iilii)Vi\ lux) at ■■Jkch diikdolc falls 
slightly t>ejiiw, a cttrtitiii nicjin lcvl^l, and llowii in thi^ vi-ini> at a much lower 
prt^Mure, which iiutt not tihi)W thu immcdi.itc i'iret:l« of each heart-hwit. 

If two ma nomut •.■»>, instead of une. were atlAcheil Irt the arlfriiil *y»lcm, 
one near the pump and (he othor further ofl'. close to the peHpheml miM- 
anct, the prrasuiv shown by the near mnnomolcr would hf fuund U> be grralcr 
than that shown by the far one. The pressure at the far point l* l«M 
becaHio some of the pressure exerlod at the near point has been uwd to drive 
tlie Huid from the near ]ioint to the far one. .'Similarly on ihe venous ude, a 
luaDomotor placed close to the peripheral region would show a higher prea- 
aure ibaD that shown by one further off, beeaiise il is the pressure still remain- 
ing iu the veins near the eapillariee which, assisted, as we shall see, by other 
cv«nts, drives the bloud onward to the larger veins. The blood-pressure is 
nt ilM highest at the root of the aorta, and al irjt hiwott at th« mouths of the 
Tcnii; cnviL', luid is falling all tbe way from une point to the uthi-r, because 
all the way it i.-> beting usi-d up to move the blool from one point tn the otlier. 
The great drop of prewure i», a^ we have said, in tlie pcrijiherai n^on, 
because more work has to be dono in driving tlic l>l<x>d through this rvgimi 
than in drlviiig the blood from the heart to this region, or from this region 
to the heart. 

Tbe manometer on the arterial side of the model shows, as we have seea, 
an (^'illation of pressure, a pulse due to each heart-l>eat, and the same pulse 
nay be felt by placing a finger, or rendered visible by placing a light lever, 
on the arterial tube. It may fbrther be seen that this pulse is most marked 
DMTMt tlie pump, and becomes fainter us we paw to the periphery; but we 
must reserve the features of the pulsa for a sjiei-ial study. On the venoiia 
side of the miwlel no pulse can be detected by tbe manometer or bv tbe 
Soger, provided that the [leripheral re*i»tancebeadoi{uatc If tbeperipWrol 
NMStaocc be iliminished, aif tiv uiiKCrewing the ctamjvt, tbeti, as ueoeaaarily 
follows from what bus gixie biifore, the pnlxe psjiseii o\-er on to tlM veixxM 
side; and. ns w'l- iihall have uccneinn to putnt out later on, tn the living 
organism tlw (>crij>b«'rHl nvistancu in {mrticular an>ai> may beat linKtao 
much lessened that a distinct pulsation anpcJin in thv win*. 

If in tlie model, when tho pump !■ in lull swing, and arlvrial pNifun.' well 
eMabltiiied. ibe arlerial tube be pricked or cut, or the sninll xidn tulw a 
be opi-ned, the water iiill gij*h out in jets, as dues blood from a cut artery tn 
the livin/ iMidy ; whereas, if the venous tulie i>e similarly pricked or nil, or 
the small lulie r t>e ojieoeit, the water will simply ooze out or well up, as 
does bliKxl fnrni a vein in tbe living body. If the arterial tube be ligatured, 
it will swell on tin- puniji Bide aud shrink on the jteripberal side; if the 
venous tube W ligatured, jt will swell on tlie side Dearwt the capillaries and 


•Kriak on the atber sidv. In short, the dead iHDdol will tliuw all tli« niiila 
fbrta of lh« circuliition which w« have as yet described. 

{ m. Id tbc- livinc lioily. hi>wever. there ore certain bel[is l« titv oircalii- 
tioa which oaniiot be iiniimed by *v<-h n roodd wilhuut intmdnciug great 
•ad UiMledrRble coiupIinaiuiiB ; bul ttine diietl)' ittri-vt the How iilniig tlio 

TIm TviDS uv in nuuir placm provided vith valvts so t'nnatrudod as to 

oAr little or no naiMance to ilie llnw from the cii|Mll«rios to tliv liparc, but 

aallv to block a reitirn lowanl lh« eaplllarirs. Hencv may cxtvra*] 

n Drought t'< War urHiii ii vein U-nds to help the blood to mnvo for- 

lownrd the Itrnrt. In tbt.- various mo vera en tn carried out bv the 

1 mitK-li-f, [>u<:h an exleninl prcmiire is brought to bear on many of 

vriii*. and 1m-dc«- tht-sc niovcnients imi«t the circulation. Even juiiiaive 

KioTrini-nla nf the limbn have n nmiltir ef^t. So, also, the in ov emeu is of 

the alintentarr canal, carried out by means of jdain muHOUlar tissue, promote 

ihe 6u* aliMig the veins coming fnini that canal, and when we eouie to deal 

vtlh tbr spleen we shall see ihat ihe plain muscular fibres which are so 

■htiadatit in that organ in mnie animids, serve by rhythiuieal contractiona 

toPsnip Ihe blood re^ularlr away iVurn the spleeu along tbeipleuic veins. 

Wlwo we t!oni« to deal n'lth respinilion, ue shall see that each enlargement 
rflJM cbeu constituting lui iDi>|iiniiiou tends to draw the bl»o<l tiiwanl the 
that, and each return i>r reiracliou of the cliesi walls in expiration lends to 
Mrs the bhiud away frotn the chnt. The nrrangenienl i>f the valvi-» nf the 
ban cauaea thin actiun of the rt^iiiradiry pump li> prriniuU' the How of blood 
io Ike dlrvctioti uf (l>e normal circiilaliun ; and, inilc^il, nen? ihr hciirl per- 
iuljr iDntinnl<M>, tlie working of this rir«piraiorv ptimp atone would li.'iid to 
itin t)if> btood from the venit oavie tlirom^h the heart iuio the nortu, and so 
In ksMt op the circiilalioii ; the force so exerted, however, would, without 
iktiia of llie iK-art, b« able to overcome s verv »iuall part only of ihe resist- 
lon ta Ihe capillaries and snull vessels of the lungs, and so would prove 
idiislly inefTectual. 

Tbefe are, then, several heljM to the flow along the veins, but it must be 

imnabered that, however useful, they are helps ooIt. and not the real cause 

tl thi> cimilaliou. The real came of the flow is tlte ventricular stroke, and 

liii i* iofficient to drive the bliMnl from the tel\ veiilricle tu the right auricle, 

when every muscle of tlie Ixidy i.i at nnl aii<l hmtlhing ii> for a while 

1, when, tlterefore, all tlte hcl]i« we are speaking of urc wanting. 

CCVrcHMMtoiuvi DettrmiHmg the Rale of (Ac Flow. 
i 132. We aaj now nun on to consider briefly the rate at which the blood 
Of through the vfmelt>. and fim the rate of flow in fA«r artfrie*. 
Vhen even a small artery is severed, a ronsidcrnble qiiantily of blood 
faapn tr\na the proximal cut end in a very short sjiaee uf time. Thai is to 
■t, ihe blood moves in tlie arterira from the iiearl lo the capillaries with a 
Tfty ninaidemble velocity. By various methods, this velocity of the blood- 
annir ha* been measured at diflerent parts of the arterial systein: llie 
■»oli>, owinK to iinpeifi'<-lio<u» in tlte meibods employed, cannot be regarded 
m Mtldaii'irily exact, iHit may be Bi-cefneil as approximately true. They 
sluiw that the vd'M-itv of the arterial >tivani u. greutnt in ihr largest aiteriea 
acar the heart, and liiniini^lxv from Ihe hmn toward the cajiillari(«. TbuiL 
ba UtYT artery of n Inrgi- atiiinal.sucfa a»th« carotid of a dog or hone, and 
ji rshab^ in the carotid of ii niiiti, thi- I>Ioih1 Howm ai t)ic rate of SOU or oOO 
■u. a irroud. In ibi< very tmull arteries Ihe rale i* probably only m ftw 


yfrthaiii. The bicmndmiaiiTnelcr nf Vnifamann. [t'ig.SI.] An •Hrry— '. y.. » 
carotid— in rlnmpod in two pliCM. ntid dividi-d bclwecii thrclonip*. TwocanulM, 
of s b<)r<! an iiMirly e4unl ni riuMible to tbut urtbo urterv. or of ■ Icddwd Irotf. mre 
Inaetti-il iii ilie two i-nds. Tbe two cauulie iiri- cotiiiecieJ by mi'iuu of two siop- 
coclCD. whii'h work togtxher. wiili Ibe two endit of a long ^last lube. b«i)t in iltD 
Rhnpo of It U. and filled nilh nnrmnl inlino Holutinn. r>r wilh a calorri) inn<icui>a* 
fluid. The clnmpK on the uricrv lieini; rnlciwud, « turn of the stoficiwk* pennit* 
tbe blood to ealvt the proximuf end of ibe lone U'lul^i along which it MMirae*. 
driTing tbe fluid out Into ib« arterj' throuub tlie dUlnl «iiil. Attached to the 
tube !■ a graduiil^d scale, by ii)e«ns of wbiiili Ihe vclociiv wiih which iho blood 
llovra along the l<ib( mny bo rpod ofl'. Even vupjiwiiig the cnnulie xa he of tbe 
•ame borp im Ihr iirlorv. it in evident that tbe oenditioiis of the flow ibrouch ihe 
tube are BUch w will only aduiit of the result tliuii gained being coutldere a »« an 
approximative eitimatlaa of the real veloolty lu the artery llselT. 

I Flo. M. 






VnumASir*! HjoiiniioianiicriEu. 
"nn ronlaJ [■mumi i-i <1<d ln<tnimaii( an Inwrlvl hi ilii- i-ot gn<ti of* rein or MHrr. Rjrl 
dMpIc utameninclil of n dbulilo uoiixick Iho bloal-ciiiTciil can Lc mule l-i T'Uk ImniadlMcty 
UuDivli tlw i"aiT*n* am, •■ 111 A, or (n )dM [littiugb ilioBailiiaMU-thapod tube, w lull.] 

The rheomeler (Slrorauhr) of T.iidnig. Thii cornuo* of two glan bulb*. J nixt 
B, Kir. C5,GamiiiunicatinK Hbovc with eueh other Hnri with the common tube '*, 
by which ^ey can be filled. Their I'lwi-r end* arc llxed in the metal d)«c b. 
Wbii-h can be mftde to ruUte, through two right anglea. round the lorrt^r dine B. 
In Ihe upper dlftc are two hole?, a and b. cnnlinaon* wlib A aod B rtejiectively, 
and in the lower di*c are Iwo nimiliir hole*, a' and h'. limilHrly continuous with 
tbe tub«e G nnd //. Hence, in the ptwition of the dliirs tthown in the flgure. the 
labe (1 i" conlinuou* throueh the two diao* with the bulb J, and the luhe // 
vilb the Ifulb B. On luming tlie diK- D thtbii):b two ri^jht anplei. tbe tube Q 
beoonea contlnoou* with R insieud of A. and the tube fl with A Jmlead of B. 
There b a further armngemeni. omitied fioni the fiKuro for tbe ntkeof oimplieitjr, 
bv which when the dii>e />iii turned Lhrou;:h one iniilend of two right anflea from 
eilbcr of (he alHire poiiitioiiii. fl brevniw directly cuiilinuoiiii with H, boib being 
campletely shut olT from the bulb*. 



Tb* niila hT llie iub« H and O an oiute (o fit exnclly into tmi c«du1» iiwrttd 
I lb* i«» cni enib of Ibe »,nttj ubnut to ti« eiptvi mealed upon, and Uavio); a 
I BMrlf *(|iia1 u jiOMibl« t(> Umt of tti« artery. 




Lrwvti>> Svaomnu did t DiAi.aAXiMttc IlKranarrtnoK or Tiik i*xt. 

Ttt sirtbod of experimcDlin^ Ih ho follows ; The dim* D, liciiig pl«c«d in thv 
IHmiillal* pontion. tn ibai u and h nrp liotli cut olT from «' and b', tin- bulb .1 
ii DM whb pun olive nil up l'> thi.' mnrk x. and Ibc bulb B, tlie rrst of A. aud 
Itejuncilon C, viib JclilriDnli'd blood; aad V M tbcn clampnl. Tbe tube* II 
ni'itntiao Bll«il with dclibtiiiiit«d b1u<Hl, ami U inaWod into tbe canul* 
if tt( tMlral, B into thai of the i>eritib«rBl, end of tiiv iirt«r>-. On rcmuviDic 
Aadmn from tlw arWry the blood Bom lbrouj;li O to //, mid an bark into tbe 
•fifty. Tbe obavtrraiioD now brgins by taniltig the due D into thr poailioa 
•km ia the (iiture; ibe blood tbrii fltwi inln .1. drinng tbi- oil there I'lmtaini^il 
«tWfor« It into iIm bulb B, iu tbv dircclioD of tbr nnon-. Ibe dofibrliMied blood 
"' — \j pnwBt In B poaunc by H inlu tin.' iirtrrj. and au into tbe nataoi. At 
HMftit tbat Ihc blood la an-n la irae to Ibe mark x, ttie disc Dw with all 
lie fsptilitv tunieil Ibrougb two ri|t;bi noglea : and thiia the bulb B. now 
J ftlltd viib oil, placr<l jn commii nidation nilh O. Tbe blood-rtreum DOW 
lira tbe nil hack iiilo .f . aitd tliu new blood in .1 tbrouicb II into ibe arler^. 
Xumm'a 1.1 ibi- nil ban wholly tvtuinvd lo ita original [Haitioii. the iltM {a agnm 
Rrii ind A raiev taorr placed ia conmunlcallon with O, and the oil onc« 

ma- , :r<>m A to It. j^hd tbts la repeated aeveral tinici. jndrcd eenerally 

■bJ Utr i-li'iiinK if lb« blood (It ih«> ailmixttire nf tbo oil with Ibr bloud iiuta an 
tu Ibr eiiicriEnrnt. Tbiia tbo (low nf bl<)o<t i* uied Iu fill uttcrtiat«ly Willi 
' HT «dl tbe ainiv of the iMilb A, whuac caviiy a* far ■■ the maik x biu Wen 
,' MMHured ; boni-L' if ibu imiubct of linitn in aay j|;lve» time tlie dUc D 
ke lurneil nxind bi- kuowD, the uuinbcr of line* A baa beoa filled b alao 
a, aad tbn> ilio quaniity of blooil wbti-h baa paatod in thai time througb 
Hia connrftt-d with ihe tube O in directly meanurcd. For instance, an p- 
;lluit ih<- 'piNKlily hrUI by Ihc Uiilb J when tille'I up to the mark z iaSce,, 

,, tj,„{ |',„g, ti,^ moment of allowiog Ibe dxtX li c.c. of b1'>od tn b<f in 

it<« to the monienl when tbeCKa{>e of Ibe laat !^ c,c. fmra the artery 
. ;... . *■■ eoniplcte. M) Hconda bad elatwrd. dnrinc »bich time A ex. 
'kal been recvived ten timea into tbe tube from tbe arte/y (all but tbetaatG c.c. 



W\it)( rcluriietl inti> ihe dit>(al |>ortioD of the artery), obviously 0.5 c.c. of blood 
liHil Hl>^^'t^<l t'miu the pruiimkl a«ctiuD of the anerj id one Mcood. Heoce, up- 
)>iniiii>; ilint tW diameter uf the caDulK'(and of the nrtery , the; being the bum] 
were 2 mm., with area Ibt-refure of 3.14 wguare mm., an outflow tbroueh the tec- 
liiiii iif (t.f) i-.o. <>r .MHi cm. in h lecond would give (?"'') a Telocity of about ISt 
mm. ill H niHiinil. 

'I'lic linnmilHi'liometer of Viemrdi [Fig. 66] is constructed on the principle of 
iiii'iiHuriti); the vt'locitv of Ihe current bv observing the amount of deviation nudet- 
>I<iiLit by u )H>iidiiliim. the tree end of irbich b»nga loosely ia the stream. A sqnsn 
or reotangutar chamber, une side of which is of iIm 
anil marked with a graduated scale in the form ot *a 
an- iif a circle, is coonected by means of two slwrt 
tuliea i(ith the two cut ends of an artery ; tiie blood 
ciitige>|uently Howh from the proximal (centrml) px- 
lion of the artery through the chamber into the disti] 
^H II '' -^t I )'«>i'tion of the artery. Within the chamber and wf 

^\ '^ '\^^\ I l«'inW fri>m its roof is a short pendulum, which when 

I ''jiji^J^^M f ||],> b!iH>d-»tream is cut off from the chamber huigi 

miitionkwH in a vertical position, but when the blood 
is allowed to flow through the chamber, is driven b; 
the fon'e of the current out of its position of rest. Tbi 
iiriiiliiliiiii in i>o |i1m'tit lliMt a murker attached to its free end travels close to [be 
joiii-r HiirfiiiT of till' glitMi nidf aUDig tlie arc of the graduated side. Hence tlie 
himiiuiit iif deviulioh fMUi u vertical position may easily be read off on the ictle 
(rum (111- ouliiile. The graduation of the scale having been carried out by eiperi' 
iiii'iitlii^' nitli HircnuiH of known velocity, the velocity can at once be calcalited 
lioiiL [lii> iiiiiiMiiil of ilevialion. 

All iiiiilnimeiil liiiMi-d on the siime |>riiK'iplc has been invented byCbauveanud 
ii»i>tovi-d liv l.orli't, Kif;. tiT. In Ilii^i the part which correeponds to the pend alum 
ill N'iri'oiill'i' iiiKtruno'iit is prolonged onteide the chamber, and thus the portion 
ullliiii till' rliHinlii'r is iiiBik' to form the fhort arm of a lever, the fulcrum of whiti 
in 111 ilie point nhiTi- ilie wall of the chiimlier is traversed, and the long arm oi 

n I yi VI M nitMi LI i; ^ii V i>k- 

■ PIII'l. 11. I'. »11< Mil to '11-11-^ ] 

Kii., 67. 

1! 1 ^IMAi-lllOll.n.Jl Ml^ f'llA^'VKAU AM> LliRTET. 

» Nii'li iiiiijn In on(Hi<]<', A soniewliat wide tube, the wall of which is at one poiD* 
i'iiiii|io?>i'<l i>f nil I III lilt riiUKiT iiiembranc, is Introduced between the two cut ^**? 
Ill 111! til ii-r> , \ hnin lij-lii K'vcr pierces the India rubber membrane. The Aot* 
ixiiiiiiiliil HI 111 III lliin IfViT jirojirliiig within the tube is moved on its fuleruni »" 
ilu' hidiii iiililiir riiij: liy llie cnrrciit of blood passing through the lube, ^"^ 
jiu'-ati'i ihv u-loi-iiy of lli'e current, the larger being the eicursion of the lever- 


n> BMnnila <iT tb* ihitrt anii glT« ri»e to fxMTMpoiuliiig iiioir«nirnli in the 
Iffrito dlractkm at the loag um buu)d« ilie tube, and ititac, hj ni«iiis of u 
BWlW MUcbMl to tilt end of ibr long arm, nirty bv dir<>i:tlr iriiicriticil »n ti 
NCMliaf MufiiCr, Thin iniitriiRivnl i* vrr^ wall iwh|ic«(l Tor nfa^trliiK chmiffra 
It tW t«Ificlt]r of till' flow. In drtcrmininK kctditl vvlocilics, for whicli |>ur)>i(te 
h tai to be exfiertnraullr gnuluat«d, it U not k> tueftil. 

la tbt capUiarw, llifl mio ia Rtowmt of all. In lh<> w«l> nf ihv frag th« 
Im u iudgeil Ur tho movement of the md corptisclfw mny \k diroctljr 
■■MfM ua<ler the microeeope br me«ti8 <>r n mk-romvter, anil i» fuuml to 
U iboul half ■ millimelrv io a wmad ; but this it pmlitiMy a tour t-slitnnttf, 
or* h m ofilr when th« rircnlstion ia somewhnt slow, slovrvr [nrrhiiiw thin 
ilal oQffht Ut he cotiaidered the normal rale, that the red coriNifclea cnti Iw 
ditiliMljr seeB. In the mummnl th« mle has been (Miniated at ibout <J.7j^ 
lAliaaMrM * »ecoa'l. but U pmbubly ()Liiclcer than even ihia. 

At nnnts tAe rein*, llie flow b verj aIuw in the small veins eiuert;ii)t; from 
Aa(H|dTlann, but JncreueiM these join into larger truuk;*, <intil iu « larj^e 
WD. rtirh aa ibe iuK>ilar <if the diij;, the rut* is ai>out 200 tnm a »ec()ii<l. 

ilSS. It will lie neci). tliMi. that the vcliidtj of the tb>w i.-> in itiTenw 
fnfOrtkM) to the width nf the bt-d, Ui the united nectional nrtOM nf the 
HML It i> grMlr*t at the aiirta, it diminuht* aloD); the arlerial xyKtcm to 
tb» (Kpillarki. to the imiicd baaei of theconw «|H>ktii of in § 112, wliere it 
iltwi,BiKl fimm theniv inenttmi again along thv. venotu avRleni. 

XaA, EimIhhI. it ix tbi" width i>f the bed, and thi> nl»n«. which tl«tcrmi»es 
ibevowrW ve|i)eil_vi>ril)c flow nt variou* [)artii of the ayrtem. The »lownc« 
it Ike flaw ill ibe niplliiriea u not due to there Iteiiig »o much more friction 
htWir narrow cbanii«U tbnn in the wider mnaU nf the larp-r arierif*. 
r« lW [•eripfaeml reeisiance atusctl by tho IriotiuD in the capilinriu> and 
•■all arleriea ia «ii obuaele not only to the flow of blo<xl thrciti>;h ibe»e xmail 
nawb where the rCMMaoee b actually generated, but also tn tlte escape of 
thg bliNxl fVoni the Urge into tlie small arlcried. and indec<l from (be nenrt 
iMtlW Iwve arteries. It eserta ita influence alont; the whole arterial iraet. 
Aail !i \t i^viouH ilini if it were this peripheral rrsialanoe which cheeked 
tbf flini in the cnpillnriM, then could be no recovery of velocity along the 
now* tract. 

lit lilood ia flowing through a cloaeil aratera of tubea, the blooilreiHeK under 
tkr influence of one propelling fi>n-e, the svstole of the ventricle, fbr tliis is 
llw li>rfe which dri<rc* the bliHHl from ^-vutriett? to auricle, though, an we have 
■■■.iltaetlaDWmialifierl in thi- >eveml parU of Ihesyatem. In xiich a >y>tem 
AtaiM <)aantity nf fluid muni gum each aecllon of the «)-*ti<in at the wim« 
!(■(, nthrrwiai- ihen- would Iw a block nt one place and a deficiency at 
i»<tkrr. If, for in«tanev. a fluid is ma<le to flow by some one Ibroe, premurc^ 
M fravlir ibrough a tulw A (Fig. W) with nn eHl«r;g«aH-n( B, it i» obrioui 
iW the *ame quantity of fluid miL<t pan 
<^n^b tbe taction h os \»bk* through the 
wii* a in lh« mme tttne— for insinnce. » 
wa*4. Othcrviec, if leas panea thrmigh b 
tJaa a, tbe fliiid wuuld aceumtilate in B, or 
V*M«. B would be emptied. In the same 
'< juU ea much lausl y»^ tn the nntc tinte 

■ifh tlie aeciioB c u paasea through a or 
t". ikit if ju"( ft* many particle* of water 

hm U' get through the unTnui teetiim a in the «ame time n* tbey have to 
(H ihruugli the br'vi>!er 'eeiiiin v. they mutt move <)nirki-r lhfi<iii;h a than 
linM^b c, or more nlowly thmiigh c ihnn thrutigh m. Fur lh» oamr r<-iuion 
flawing along a river impelled hy ana fbrc« — vix.. that of gravity — 

FU. S1L 


nisltea ntpidly ihitiuiijh a "nnrrovf" nni] flows sluegUlily wlieii ilic rivor 
widens oui iiiio a " bruail." The flow tbrotigb B will be iimilarly 9lack<*»cd 
if B, instead of beioft simply a smgh enlarge men I of tlic tulie A, couslstK of 
a number of small liibeti hraiioliiu^ out from A, wilti a uuiied wHlioiial nrra 
neater Uiau the seclioiwl area of A. fr) i-aeh of auch smmll tulxw. nl tbo 
nn« c, for instuiire, the Row will be ^lawer thitu at a, wlierc the *ranll tubci> 
branch out from A, or at h, wliere they join RKsin to form n MR^le labo. 
Heiicv it is thai iho blood rushes swiflly through Lh<- nrliu-i», tarrm slowljr 
through the citgiillarius, but ipiickeiis il* |inco i^aiii in ttie vdi». 

An apparent wnlradii'tion to thiH principle t-tint tliv rat^ of flow in depoo- 
dont ou the widlli of the bed Ls srcri in the emu wlivrv, the fluid having 
allemativu mutra, one of the route* U temporarily widcmxl. Suppose a tuM 
A dividing into two brnncbes of equal length x and y which unite again to 
form the tube T. Suppose, to stnrt with, that J; and y are nf equal diameter; 
then tlio resistance oHi^rcd by each bein^ equal, the tli>w nill be equally 
rapid through the two. being juet to rapid that as mucli fluid dbmcs ta a 
eiven lime tbrotij^h r and y together a;^ pas8L« thmugh A or tnrough f. 
But Don' suppose II to be widened ; the widening will diminish the re«i!taDoe 
ofler«d by y. nnd in cotiseqaeooe, supposing that no material chnnge lake* 
place in the pra^ui'e or furct> which is driving the fluid along, more fluid nitl 
now \Mae alonj; t^ in a Kiven time than did before ; that is to say, the raptdi^ 
of the flow in ,v *^'>11 h^ incn-ased. It will be increased at the expense of the 
flow thruu);h ^, since it will still hold good that the flow through f and y 
together is equal to the flow through .4 and through I'. We shall hare 
occasion later on to point out that u vmall arlery, or a set of small artertee, 
Diay lie more or Inat suddenly widened without materi<llv affecting the 
general bhMKl-jjrWMUr^ which is ilriving the blood through the artery or set 
of ait«'rii». In such caaea the flow of blooil l.hrongh thi- widt-nvd artery or 
arteries is lor the lime bein;^ increased in rapidity, not only in »{utc of, but 
actually in consequence of. the artery beinK widened. 

[t must be understood in fact that this dependence of lite rapidity of tlie 
Sow on the width of the bed applies to the general rate of flow of the whole 
circulation, and that, besides the above instance, other special and trmporary 
varttilions occur due to particular circumstances. Thus cJianges of pressure 
may alter the rnjiidity of flow. The cause of the How through l)i« whole 
system is the prmsnrc of the ventrtt^ular systole mauitesied as what we have 
Qklled blood- pre»u re. At each point alou^ the system nearer the left 
veotxiole, and therefore f\irlbcr from the right auricle, the pressure is greater 
than at a point further fVoni the left veutricTe and so nearer the right aurirle ; 
it is this aitTcrenoc of prewure which id the real cause of the flow from the 
WW p(^nt li> tlic other; and other things being equal the rapidity of the flow 
will depend on the umounl of the diiPcrence of pn!*ture. Uence. temporary 
or local variatiorm in rapiditv of flow way he cau*cii by the eatai)li»lunent 
ftf IciDitorar}- or local diflcrcnccs of prewure. For (example, at any point 
«l<mg the arterial itystem the How is incrcjiixil in rajiidity during the tern* 

Sorary incri'ase of preeture due to the ventricular ayntole, i. r^ the puUe, and 
iminishcd during the sulmcqueiit Icmpnniry dccrcn»i% the increaie and 
deorease being the more marked the n<Mrcr the point to the heart. And we 
•liaU probnbly meet Inter on with other mstnncefl. 

S IS4. Time of Ifie ftitirv Mmiil. It is obvious from ihu for^>ing that a 
red corpuscle in j>erforming the whole circuit, in travilling Irom the lel\ 
venlricle back to the left ventricle, would spend a large portion of it* limo 
in the eapillarivs. uiinule arteries, and vetne. The eniirc time taken up in 
the whole cin-uil has been approximately attimaled by measuring the time it 
takes for an ca»ily recoguiied clieuical substance at^r itijectioD into the 





Jnnkr nin of one aide to «ppesr in lh« blood of ilie jugular v«io of the 

Wlii1«MBklI')iunllti« (if blood an* being ilrawn at fiei)U«Dtl7 r«i)eaf«d iut«rriilB 
A«fn thp jufnlar vein of iin^Hiclc. or wlillf Uieblowl from the voin Uboing allovc^l 
«0 bll in a uiiiiutr Klrraui on in ahaotbrnt paper cnverinK loatti traTrlUug xurfacc, 
tfa Imn nit mrli aa putamiiim rrrrncyiniiJi' (or iinrfcrably loiJiutn frrrric^rnniile ■« 
BMtiag nora innoruoiii) b injectPil iiii'o tlie jugular vrin of theotlit'r nide. If Uie 
siwfl of tb« Injecltod be Doled, and ibo time nder Ibe Injection into one aide at 
«i|iidi vniltaco of the pratVRca of (be iron aalt can bv detected in tho aaniple of 
l>too <l fron llic Tpio of the fltber lidr ))« nntod, tbi* Ki*^*" tbr time it baa taken ibe 
«aU tm pflrCwm Ibe cin-uit ; and on the «uppwiitiun that mere difTuiiioB doea not 

anlwUly aifrct Ibc n>«uli, tbe time nblcb it takca tbc blood lo perform tlte tame 

dftaH i« ihenby girvn. 

In the hone Hub time baa been experinieDlallr detenoined at about 30 
■MMwb moA ia the dog at about IG eecuada. In man it ia ]>robablv from 20 
10 35 wteuoda. 

TtkloK the mio of flow ilirou(;b tb« capillaries at about I iniu. a second it 
•uM tue ■ oorpuiwlc as lou^ a time lo net ihrouifU about 20 miti. of capil- 
bm na to perforin (he wbole ciriMiit. Ileo<«, if aiir corpuscle bad iu iu 
cinBlt to poaB ibroui^b 10 iiiiu. of rapillariiis. balf ibe abole time of ila 
jmef would be spent in the narrow obuiinelR uf the capillarieiL Iniuinticb 
aiW iMir]nee0 served by ibe bluod are ebietljr carried uut i» the c-apillariv*, 
it ii oWiouslf uf Btlvaiilage tbat iU atair in them should be |>ruliiii^il. 
Hon, bnwerer, the avera)|:v leiiEtli of a capilWy is sbout O.S mm., nlK>ut 
UfaieKind isspeui in tbe atpillaries of the lIsHuex and another half tecond 
is the oapillMries of the lunjpt. 

iUtSi We BIST now briefly fuiuniariM' tlio broud f«iturt» of the dreulH' 
oco, vhicli Kc bavr wen may be explained on purely ph)>i«it nrindples, it 
biWuKiinex) Ihat the ventricle delivers a eerlnin quanlUy of blond nilh a 
(ffUui force int'> ih* aorta al regular intervals, and tliat the physical pro|>- 
ettki of th« btoodvcen-ls remain the eame. 

Ws bare seen that owing to tho poriphervl rvcislanee ofl'ered by the cap)'' 
IniaaadKnall vnseI»lhedi>Fvteflectof ibe ventricular stroke is to establisb 
to tlie artAries a mean arterial premiire which is greatest at the root of tbe 
aorta and diminishes lowsrd the small arieries, some of it bcinj* useil up to 
4rffs ibe blood from the aorta to the small arteries, but which retains at tbe 
n|>M of the small arteria euffldeiit power lo drive through tbe small 
sttHin.capillanci'. and reins jusi as much blood as is beioE thrown into the 
aula by the ventrirular strukt-. We have seen, further, that iu the large 
ift«i« at eaeb stroke ibe proauro lUiti and fnlla a little above and belov 
tisHMan, tbu-- omstiluiitig tbe puW, but ihai thti vxm dbtension with tla 
•okuteat recoil dtminisbca along tlie arterial ltbci and liuallr vaimlua ; it 
diaiaUies and vaulBhes beoiuise it loo, like the wliole force uf tlie ventricular 
Hnlw, of a fraction of which it i* the cxprcMtioti, in i»ed up in eatabliohing 
tka nam pranure: we «hall, however, coiinder ngnin later on the «jiecial 
falaras of ihU pulse. We havi; sura, further, ibnt tbe laak of driving tbe 
Uwd through thi* ]H'ripl>i.-nil rmslnnee of tbe sniall arlerii.ii and canilTaries 
nOMiiBea much of this im-an pmuiure, which ooiuequently t* much \v» in 
■Wsmtll teioH than in ibo en rrc« ponding rmall arterii.v, but ihat sullicienl 
HBahv l» drive the blinx), even without tl>e help of tbe auxiliary agenU 
*Ueb arv generally in action, from the small vetos right back to the auricle. 
Ui^^ wtliav* seen Ibnt while tbe aliovo ia ihe cause of the Bow from 
vnlnde to auricle, lh>- cban^iing rale of the How, the diuiininbin^ nwiftncsa 
ia ths arterini, the sluf^fpoh crawl through the ciipillarice, Ibe incrcnung 



qoicknesB through the veins are determined by ibe cliUigtDg wliJlh ot tbe 
Tuoultr " bed," 

Befiire vre proceed to cunsider any ftirllier dnnilH lu lo ih"- |iht>iii)TOi.*iw iif 
the Boir tlirbUjih the veaieU, we aiuu turu iiiiulo tu fttutly tliv hi«rt. 


^ 126. 'I'lie heart » a vitlvulnr piiiii|> which works on inecbsiiiciil ]trincU 
)>te:d. bill ihe motive (wwcr of which is supplied by tbe contraetiuu of it* 
niuaouhir 6brci. Its Bt-lioii conso<]uoiilly presents probleiuii which ate piinly 
Riecbaiii<nl and partly vital. lie>;arded lut a pump, its eflects are determiii«il 
by Ihe fre'iueiiry ul' the beats, by tite force of each bent, liy the vluiracUr of 
oavh beat — m bether, lor ioatance. slow aiui liiiiti-rinx. <>r Minldeii and Mhar|i — 
and by the quantity of fluid ejected at each beat. Ilen{«, with a given 
frttqucuey, force, ana character uf lieal. and a given quantity i^bctMl at vach 
h<'tii, the pi-obleiiiB which have to be deiili tviih uiv for the miitit inrt 
iticchaiiictil. Tlie viinl prubleiuB are I'hictty coiinecie<l ivilh tlic c-humv which 
(letcnuiiie the frci|ueucy, fiirce, nnd cliaruut^r of the bcMit. The qiinniity 
eivctml III wich liuil i* govrrned iiiore by the iitnto of tins r«l of the Iwdy 
loan hv ihiit of the heart Ilnelf. 

The Phnwmena of the Normal Beat 

The vuibk movenimts. When tbe chest of n iiianinml is opened anil arti* 
ficbil reapimtiiiii kept up tbe heart may he watetied beatinff- Owinjc to tb« 
ivinoval of the ctiait-wall, what ia aeeix is not abwlulety identind with what 
tak«« phtcc within tbe intact chest, but tlie main eventa are tlie lamc in both 
ewes. A complete beat of the whole heart or catdiac cycle, may be obwrv«d 
to take place a» t'ollnw^ : 

The grvot vetni>, inferior and superior renn cavic, and pidmouary reina 
are seen, while full of blood, to contract in the nuighburhood of the bean ; 
the contrnctioii runs in a peristaltic wave toward tbe auricles, increasing in 
inieiiHity as it j^oes. Arrived st the auricles, which nre then full of blood, 
the wave suddenly spreado, at a nitc totj rapid to be fairly jud>,'ed by the eye, 
over tbe whole of those organs, which accordingly contract with a sudden 
(harp fytitole. In the systole, the walls of tbe auricles press toward the 
auriciilo-ventricular orifices, and the auricular appendn^'cs arc drawn inward, 
Wcuniiug timallcr and paler. I>urinK the auHoulitr systole, tlie ventrioloi 
may be iteen to become turgid. Then follows, as it were imrueUiately, the 
the v<'ntncuhir «ystule, during which the ventricles become more conical. 
Held Wlwi-en the fingerii tbey are felt to become tense and hard. A» On 

Kitolc progn«M>i, the aorta aii<l pulmonary arteries expand and elongnio, 
e apex u tiltcid tilighlly upwanl, and llie heart Iwidta Homewhal on ita long 
azii, moving frnm tne \t(t and behind toward the front and right »o that 
more of the left, ventricle beoonie* da^layetl. Ait the MVNtolo given way to 
Ibe •uoceeding ilitwtolc. thp vpntricl™ n-sunie iJitir firevniu!t form and pOM- 
tion, the norla and pulmomiry nrirry shrink aud MlK>rli^n, the heart tnmi 
back toward the left, and thnu the cvcln is I'^iniplrifW. 

Ill tbe normal l>cat, the two venincleM are |H'rlci-lly nvnobronout in action, 
they contract at the same time and relax at ili" :<nmc lime, and the two 
Uindee are similarly synchronous in action. It has Wm maintttim-d, how- 
•rer, that the synchranism may at times tint be [lerlect. 

Beibre we atlempt to study in detail the several [wirts of thia complicated 
•orica of will be convenient Intake a rapid survey of what is taking 
plao« within the heart during such a cycle. 



I UT. Thf oirtiioe rgtlf, IVe tany lake aa ilie end of ifa« cycle the moment 
HvWb the vcolrkW liitvint: mptipil th«ir (.■onteois have relaxed and 
nCnnriJ (•> tbc diaslolic or rt^lin^' [vi«jiiiiii nnd form. At ihiit inoni^nt the 
kbtd k flowing frc«h- with n fair rapidity, but h« we have aeeu at a very low 
pmtn, ihrodgh the venv l-svh- into (he riKlit auricle < we inuy I'uiitiiMi 
Mfflnt at firat lo (he ri>,'ht side), am) ^iiir« ihtftv a now ocithing lo kmp 
lt*liwiM|nd valve shut, ^iii>e uf Ihis bliiod j)r<>biil>lv KmU ita nay into itu) 
nnliM* abo. Thia guea on for aome Hltle lime, aaJ iheu comt* ihr nharp, 
Awt n«toI« of lh« auricle, whJeh, since U heuiioii ai> wo have mmmi iw> a wave 
if cninctioD ninniiit; forwarxl ulimg ilic emb «r the row cnvio, driviw Um) 
Uoij net baekwanl iu(i> iho vciii.-> Imi Kinvanl iiidi (he vfiotriclti: thifl end 
b fclthar aeeurvd by thf liivt thai (h« ayttolv bti* bchiml it un (hi- veniiua 
MlJw fmwurv ul' ihc blixid in (be rcin», incrtuuiiiit: an no have Eevo back- 
Mnl Inward tlie cafiilliirU^, aiid before i( tbt^ ivlatively empty cavitv of lb« 
muide in wbich the ]>rw»iiire ui at fintt very low. By the eomplotc oon- 
tflKtMO of the auricular wall* (li<- oi<mplclo or nearly complete emptying of 
thttaTft* i* imturvd. Nn valvi-fl an- prtvcnt io the mouth of the eutterior 
*nacava, for (he^ arc not ntx-dtd ; and the imperfect Eustachian valve at 
ifenovtli of th*- inferior vena cava cannot bo of any gmt use in the adult, 
'i in its BU'Tv <lt-vclo|x<(l mate in the fo-tiis it hail an important funeti'iD 
' the blood of the inferior vena cava thrmi^h (lie fommen ovale 
; anriclfk Tbe valvee in tbc '-orouary vein ari-, howercr, probably 
' DM in pT\-<rcn(int; n rertns in(o that vessel. 
A* llie blooil \a being driven by the .-itiriciilar systole Into the rentiicle, a 
irflut current ia protmblv tel up, by which the blood, passing along the 
I of the ventricle, |>elB net ween iheiu and the flap« of tbc triiiiAjml valve 
B iMtda to flo»t these up, IFigt. t>9, TO.j It is further probable (hat tbfi 
' ntax current, continuing komewhat later than (be niin inii> (ho vvn- 
', h tufficient (II hrinz the flaiiH into ap|witiilion, without any regurgitation 
inu likC snricle, at the eroac <>f ihc auricuUir avfiole, before the ventricular 




7io. 70. 

PuiiatM w ViLTD -ir illl (lutil. AHk Itiunh 

mute haa beyiiit. According to wme authoiv, however, the cloeure of (he 
nln m vflected, at the very beg^nntne of (be vcn(ricular svHole, bv the 
Matrmctiua of the papillary mn«cle«; the churrUe tcndiue» of a papillary 

cU are attached tu the adjnoiTni edge* of two Hajs. »i> that (lie shortening 

^ • moacle (end« tu bring lh<M edgoa iolu apposition. 



The mirit^iilnr avHtolc is n" we Imre Htii] immcdiKtvly folio' 
t]ie ventricle. Whether th« contrnclinti of the vmtrii-ular vniiie (which ks 
we fhitll a'« ia n «iinnl« though prulungv.! contraction antl not a tctunus) 
begin? Kt one point una swiHtlr tnivels over Ibo rest of the Hbres, or )>eeiiia 
alfovcr the ventricle ut unce, ie n >(neeti()n not at present definitely #eUled; 
but ill any cose the wrnllB exerl on the contentM it preesure which in aoon 
brought to bear on the whole conlcnte uid very rapidly rises to a maxitouio. 
ITie only effeel of tliis iiicrenaiug iiilru-ventriculiir pmcure llpoD the vnlve 
ia to render the valve more and ruore tense, and in consequence more tecure, 
llie cbordot tendiaie (llie slackeoinj; of which through the change of form of 
the ventricle is pmbably obviated by a regulative coiitraeiion >if the impillar^ 
ntuscles) at the eam« time preventing the valve from beinj^ inverted or cv«a 
bulging largely into the auricle, and indeed, accur<ling to onuie uhoerven, 
kiKiping the ralvular aheet actually convex to the ventricular cavity, br I 
which tuean» ibi; complete emptying of the ventricle is inore fullr eJlecWo. < 
[Fipi. tJO, 70-1 Thtt connection, to which we have juM rderreil, of the chordte | 
of tlie Mimv pnpillan* inuxcle with the ndjaoent etjgee of two tia\», ntiHi iiMttU i 
in kvi;piu^ the HiipK in more complete appiiiitiou. Moreover ihii extreme 
bordcn^ of the vaiv<9, oul*ide ihc attach men Li of the chordiK, are oxomnvtly 1 
thin, so that when the valve i:< closed, ihete thin ;iiirti<iuii an? prcn>cd flat 
together bsek to buck ; bencc, while the tougher wnlral piirl» ol the vslve» 
bear the force of the ventricular tynUih, the iip|>ntcd thin memhranou* 
edge*. pmMul togvahcr hy the blood, niort- cuiupletcly Mccuru the cloewre of 
the orilice. 

At the cimi men cement of the vontricular syHlolo the semilnDar vslves of i 
the nulmonarv artery arc ckifcil, and nnr kept elwcd by the high prcsnire ot ' 
the nlood in the artery. Ae, however, the ventricle continue* to pre» with 
greater and greater force on it« contents, making the ventricle bard ai>d 
teoBe to the touch, the pressure within the ventricle becomes greater than 
that in the pulmonary artery and thin greater preeeure forces open the wmi- 
lunar valves and allows the esca[>e of the contents into the artery. The 
ventricular arstole nuiy he seen and felt in the expiiseil heart to he of wmie | 
dnraliou ; it i» xtning enough and long enough to empty the ventricle com* 
]>lelcly ; indeed, n* wc ehslTsee, it pniliably lusts hinger than the diseliargtti 
of blood. Ml that lliere is a brief period <)uring which tlie ventricle is riaptr: 
but yet contracted. 

I>iiring the ventricular systole the .wmiliinar valviw are prtascd outwnni 
towan) but not close to the arterial walln, reflux enrn'nl» protmbly keeping 
tbeiD in an intermediate position, so tbiiC their orifice fornui an e<()iii lateral 
triangle with curved sides ; they thus offer litlh- ohi>tneIe to the escape uf 
blooa from the cavity of the ventricle. The ventricle n» we have seen pro-, 
pels the blood with great furce and rapidity into the pulmonary artery, and! 
the whole contents are i^|>eeilily t^oc1«d. How, when a force which is driving 
a fluid with great rnpidiiy along ft closed channel suddenly ceases to act. the, 
fluid, by its momentum, conlinuee to move onward aAer the force has ceased ;: 
in coDEequence of this « negative pressure makes its sppeanncc in the rear: 
of the fluid, uid. sucking the fluid back again, seU up a reflux current. Sol 
when the last portions of blood leave the ventricle a negative pressure makes' 
its apMArutce behind them, and leads to a reflux current fnim the ar1«ry 
toward the ventricle. This alone would be suflieient to bring the valreii 
Kweiber ; and, in the opinion of some, is tlie real cause of the closure of tht, 
vdv4« ; others, however, as we idiall nee later on, mainlniu that su1)se<p)eut lo' 
tbi* reflux due lo mere negative preaaure a somewhat later reflux, in which 
the elastic reaction of the arli-rmi walU in cuiiri^rncd. mure cumplet<'ly (ills 
and rvndent tense llie pocketx, cauniug their free margins to con>e into close 




od Irai omUuit. «oi) thus eoliv«ly blocks tlte my. Tim corpora Arnotii 
■■I ii iIm etntn. mkI th« tliiu ineuibniiiouii teabiona or luuulw an bn>ii)^t 
■Wtim amavition. As in tbe tni^ua]>iil valv(«.aa here, while the iiittHura 
4f llvbhioa ■ bont* bj ilie tAu^bcr bu'lies of i)ie iwreral vfth-M, eii«h two 
duD idjMHii luniilw, prettied to;^tber br tliv bliiol aL-iing no both nidca of 
lbaa.Bl* kcM in ci>i»|ili!lf cuiiloct, n'tlbotil nnr Mraiii being put ujioa thuin ; 
iitUi wftf u* orifice ia cbdol iti » iiuutt eflincni itinDnt-r. 

nn»l«Baai4«|iwtef6and«tion rorthcmw put hnrnt'l by BrQckv Ibitt durinc 
ilttHlrioiUf (TKUile the flaps are prene<t bjuk ll*t nxainst tlir arliTii! witlt!>. uiicf 
li itt ou« of tM Kuri* coinpl«teljr cover tip lfa« orifiMi* of the corutiurj- Hrirries, 
■ ikti Uw flow «f blood from tbc aorta ioto ihe ooronarf arlerioa can ukc plaL-e 
«lf darinc lb« vanlricnlar clia*lo)e or at tfa* "nrf beginning of th« ayatolv. aoil 
Malal)<larlngihf «7«tole ila«lf. 

Tbt vootriciiiar ■r«to]« now ywM olT. tbe mitMulKr wnll« reliix, ibo 
taDUide nrtitnu to it8 pnvioas form Ktid positiun, aiid tiit? cyd« is onoe 

What tliui Uiko pUee in th« rivht tidti tnkr» ninety in the teft side also, 
tWi it ihe Hnic Kiddon »bnrp uiriouUr ayHtfilc Wginnin^; »t the roi>l« of 
the pilmuoary vcin». lb<' kkhp «y>Uile of tho venlricli?. but, n« n'e ithni] see, 
"M murh Hi'irc |H>wiirfiil wild I'xvrting niiurh rioi'p fi>rce ; tho mitral Talv« 
w'tik iu iwu fla^ig n4-la exactl;- like tlii! trictispid valve, and tbe aotioD of the 
wilnnar valvm of ibc aorta simply rc|Mtata that of the v«jv« of the 
pafanaarjr arter?. 

Wc tmT now proceed to sludv some of the oardia« eventa in deuil. 

fW. IV rJtaivfr of fartH. 'I'lie exftct detemiinulion of the chan^ in 
Un nd poailioii of tbe heart, especially of the veiitriclcs, during n wdiao 
tjek b au«ud«() with difficullios- 

7W vmtrielea. f<>r ini>lanov. are c'>ntinuallv cbaoging their form ; they 
(faug* wbik llwir cavitico are l>eiii)i tilleil I'rom thu auricles, lliev chan^ 
nVk i1m oiaifmctioD of their wiilU i-* iMiinjc up the prwaure on dicir con. 
Kan, Umj ehaiw* while under ihe iiil1ii(-n<<e of that pnwure tbeJr oont4«ta 
bitag dbdiargM imo tbo imeritv. lunl they cbiui)^ wlico, their cBviliM 
hanig bosn enipti«d, tbi-ir mii«.-nliir tnitl» relax. 

. Wa may tnk*- it f»r icninteil itiiU the intenml ejivitics are oblitcraied by 
tb( qntou. for it a probable Ibat pmciir-iilly tlte nhotc oonlcou are driven 
•01 tt cacb struko, and probulily ido each citvity is emptied from ii» apox 
maanl iha mouth of lb« nrli^ry. 

VTitb ragard to cbtiiijji-s in oxterniil form, there sMou do doubt that the 
wle-ton'te iliiuiMiter is much leaseawd. It Mti-ms also clear that the fro»l-to- 
kack dtanteter b grciilrr diiHttg lh« nhole time nl' the »y»tole than during 
thciiaKule, the incrcow Lakin;; |>Iii(M! during tlw finl part of tbe sy»to1c. u 
i%bl lever be {ttaccl on (tit- sorlnce of the heart of a mammal. tl)L> chesl 
hinsg baao opened and arlilicial respiration beinj; kept un, some such curve 
« thu raptCMnied in Fig. 7 1 is obtained. 'Die rise of tho lever in dcMribing 
mA a curve is duo to the elevation of iho part of tbe fr-int turfac? of lli« 
heart on whicli Ihe lover ia resting, ^^uch an clevnti'Xi iui)<ht be caused, 
«ipMially if the lever avre placed near the apes, by Ihe heiirl being " tilted " 
' ntii the ayatule. but oiily a siimll portion at most of ibe rise can 
. Ill tbia cause : the rise is perhaps best aoen when tbe lever ia 
. ui lUc middle (loriiiii) uf the ventricle, and inusl be chieHy due to an 
I ia thr fr'ini-li>-Uick diumeler of tbe ventricle during llie heal, Wu 
dwniaa ihit curve later on iu oonuevtiou with other eurvee and may 
•|tly aty that the iiurt uf the curve IWtm b' to </ probably oorresmn^ 
lathe actoai ajntole of the ventricle, Ihal ia to the lioie during which the 




Gbr«a of ilie ventrit^le are iiDd«rKoiu|t contriictitm, the suilden full from <£ 
(iiiH'iiH r«]>reKDtiug the relaxntion whii-li i'onm tlic Orel purt of lli« <)i»>tale. 
If (hU iuterpretulion of ihe curve fie eurreet, it U ukviouii llinL the froui'to- 
bitck diameter ia K'^»'>r duniifr the whule of the nvslitle ilmii ti 1* during , 
diuatole, siiwe tlie lever t.i raueil U]> all thin time. 



Cnon iuvi9(o Bnn nvciiMt. Tar Ivsisn-rciiLK cuuve hjhui M VmiuTiixai r*a Sannnv 

Tilis increase of (he froDC-to-bacIt dinmeter oonibinc<l uith a decrease of 
the »i'k--to-eide diameter has fur u rotult a chaoge in the form of the Mclioa 
of the bnso of the ventricles. I>uriiiK the diajitulc thin hiis somewhat ibe 
form of ail ellipse with the lon^; axis from side to ude. but with the fr<><it 
part of the ellipse much more tunvex ihaii the bock, wnoe the back siirfsc* 
of tbe veDtriclee is soiueMlmt llatiencd. DuriuK ihosyMnle Ibis elli|M>e is by 
the short«Diiig of the siik-lo aiile diaint-ter luji) the increiue of the fniiiMo- 
back diameter cimverUil iiilo a ti).'itrc: much mure Dearly ri'aeuibliiix a cirrJe. 
It ii> iir^tM), moreover, ihat the uhole uf the bii-ii: i> const rii-lol. and that lite 
greater dficiency "('the iiurioiihi-vrutriridar x'ulven U ihurtrliy secured. 

An Ut the bchaviur of the long diameler frum ban; Ui afiex «bgH.-rv<:ri arc 
not acr(«d. Some maitilaiii thai it in Khurleiieil, n:ut tithere that it u prac- 
tically iinchaDgvil. If iiiiy ■>hi'rlcnitig dm* lake plarv, it iiiuttt hv largely 
conipennuted by the clongatioii of tbe gnmt vvmcN, which, lu iilalcd above, 
may be MtMi in aii iQ»|>ectioii of tbe healing hcnrt. For (here i» evidfocr 
that the apex, though ns we have neon it i» during the aysttdo «omcwba( 
twisted round aiid at the same tiiDo brought closer to the chMt-wall, does 

I "Rw Tenia*) oi tnilua ennai llnH (icxincrii of elrr In} inlrudUMO inio ilili niul many ulWr 
eUTTWUVOf <u* fat tbe burpotD-f uiLiuurlDx luiuor Ihr nnt\-r. A mii>|il<*U' I'linu iliuuld eiblMI 
sn "abvelMS" Una. TliU hiht Ut iln^n Ity jiilnwitiii ih^ U-vt^r^ nmuatfnl t'tt E.h<^ nivrliiivitl bgl 
icmalntiWBl mt. toiurk ullli 1k |<:<1ii[ <m ihv monlliix •urfaco tti Id wison : n atnttalil line, tlip 
■liiiiiwi UEic, I# ibiu 4c«ct11jh1. anil nia) betlmwn tvSipear aAcr Oit^ oiirvu tiHiir H inue. aurl nuj 
b* pUcAd BU-n ur tn*a>rKtily brlrjw Uicvunv. Wluin a lunlnK-6>[lt or ulhi-r llinv-iuaikDt li> luol 
tbvUni^nr (tif ij]-nk"tTijir^k.r .-.r n i;nriln«^^i in*-"!!;-!! t>»< c>nnw if iIjd liiiilriK-'irk will «4vitf m 40 
StaclWB titiv. Af: liiu bn-[i iriro <rilltiE •iifftti?!.- iliinilil rt- hrdiisht t<*(\ imncli 

SfOAlUun ihuT i^j. i< luvc: ix^m <in<: iTiIni ■>f ihv ptiitv ulik'b It liclHlrcd bi 

aiuti if tlicluvv-.- . . ijilv mnrnl n' ■ iIl. ,..i r ..( rliu 1m tt will (l»<-rib« • wcnuail 

nf ■ olrriv lUir ri^Mirr til itliijila Itr* mi t^' '<i H^tffiuiii •ifniM Tiv nudv louf 

E«ioai[h to cm luili IIil- ciitv* rniil ilic >ii< ' <it: cimy nr nitici Uni^iniirklni 

Ifakei Wberv UilaUiIruwii- H}' itidvIi^ iTir^ ' ' ^ l[>I iiTt<l forfaiil ^linlbit vv^mmli 

oT rlrclw nujr t» liruwu lti(T>u«li iiiluT .• tin' liii» <i. 0. / lu Kie ;i won Ibn) 

4nwu. Tht dittJ>n« tM.<twrrii inv tv>< '' vhu- l»i rjuiitunT) uri Uw tunlrii^-lhTk 

0SI1C or DtbDr Uiiiocurrc. oroQ lli« nlivcb^i - n,.! ,r irio* ni'tv t>,- ilmwia oi> lUn inicliitf ancf 

lumuuval ttoiD Ibu ntunlliit; liuimnuiut in liiu loUouii^i: *aj i TuKi' i> inirof «>ii>[iaB«. incliiu 
pdntt «r wlik'h an lixnl iiui m far ifian M Dii' IitiuiIi ■.•! [)iu li>vi*r uvl In ihu e>|«r4nirni. 
iMaNiPod ttnnt Ua axil tc> lla uruinf i">JLii l^i iikrj^n- •<< \Ui- ruEiiiiimMi^ eI^ipI Uic imviliinn mi tbv 
mttncof ilicMnirvof tin: cln-lcnf ubn-ii r itir |>r>.'vi<iii-lF ilniMti <'i]rtnl liniH Umnt a 

•KKiMiK- Thniucli it^ orati.iT Omv a Jr ' < iTk- hiivlkvA. [Iy Vorg^rte imp |kj4nt nf tbe 

eoDpaM oil I 111* line iiui riii.iJnu ii niium : i -. ' ■ iiiM or CKHnnI a •ci;iiiv<t( '>( a ffrtl* ina;i b* 

ontwn ■!> K* I'l r<ii piriv |."ii' 'i ' ii' -nrrv itu: ;^;4lj Imi Jnlr>«l. ikTiilnl«'i ibi' nli«4<k>«4i hfiponhM oiiir 

kloe. Siicli aacciDijni oj ii> iir luwl for Uie tmmc git^ri"^'*'^ "^ 'l><^ nrt^liinl \ttiv atifl may 

nnnibrror nui^li H^rnnr'i- "I'll '• 'I'lmo 



bM doD^ iti [HMition up or dowo — J. «., iu tJie lotifi iixU oi tlto body. If 
iairabliii or iIi>k u needle be tbiuHt tfanmicb ibc fhtHi-utill m Ibai ita iioiiit 
fliiDp* i[il)> ibe n|>ex of tlie heart, ihouxb tbo uevdio (piiviini, itM IkwI 
MW neitber up our down, fts il would do if iu poiitl in tbu apvx moved 
d«*n M ti|i. 

Bnadly ape«kiiig, (ben, dtiriuE sj'sUtle the v<uilHcl*x> uiidvnjn n dlmiDiilioQ 
tt bul vulufuD, njiijil Ut ibe voltime uf cxkiIviiIb diM'bargvd Into Uh) grvat 
imit{tor tb' wmllv tlwnuvlvts, like nil tiiU!«uUir ittruclum, niUiii Uieir 
nliS* dariaK contractiuu, **ve for i'linngni wliicli ninv take pliicc in the 
qoutitf of blood cKintiiiDrd iii ibvir bUH>ilv»M'!i>. nr of lyni|>h in cbt.i iiiler- 
■nmkr t|wot«), vrbilc tiwy iind«rgn a chunsc nf form whiih mov be 
ilMrilMd a» that from a ronghly bemisphcricariigiira wilh un irrcgularly 
tUlMiad irction t» n iiii>r>' rvtruliir com- with a circular biiw. 

fill. I'-inUar imi>ul*r. If (Ih- haiiil Id- plitircd oti ih? cbcat, R shock or 
llfalM will be fell Ki rncb iM.'at. mid on I'xnmiimiion ihis iiDpulse, " CArdiao 
bfviK" <ii)l be limnd l» Ih< >yiii-lironoii8 with thi- s)-«lolf of tbo vontricle. 
In mm, the cardiac inip4iUp niciy \vt must dislinclty fell in the fillfa cuetid 
intfipac*, alMUt an inch lioluw und a tittle to tli« meditiii «ide of the lell 
■fftfc Id an animal (he wime impulte iiiny also be felt iu ttnoUier way — 
rit, by makiui; nn incision throuch (he diuiilimgin from the abduinen, aod 
phnntC (be fin^vr between the cheM-wall and the apex. It ibeu can be di»- 
(intllT rccuentied a» the retiull of (he hardeiiin); of the ventricle during the 
■iNiH. Atid the impulse which is feU on the outside i>f the cheM it chielly 
lM«Act of the same hardeuini^ uf the itatiunury |>"r(iou of (he vetitricio In 
amaa with tlie cb(«t wall, tmuimitted thruuith the che«t-wull to (he Rugvi, 
la Mm dacfid elate, during dia!>lole, the apex is (iu a atmidin;; )i<i»iti»n. nl 
karti ■( (bin )Hiiiil iti contact with the cheit-wtti], lyin^ Wini-en it and the 
MhaUy nviMaiit (ttaphrazin. During the »y>t<>lc, wliilc being briiiight 
cMwr to the chnt-aairby (be lihiug of iW ventricle and by the move- 
Ifl ihr frrnit iwd to the right, of which wc hnvc nlrcadv tipoken. it 
ly gmwB Iciiw and hanl. The vcntriclw. in executing ificir «yttale, 
l/i cuntnict agaiiiKt n-«i«tnncc. They have to pru(lu«^ within (heir 
anvm pretMirrs greater than those in the noria and pulniuiiiiry arteries, 
(■yoctifclr. Thin ii. iit fact, tltc object of the •yctolf; Hence, during the 
•idl avtfote, (be ventricular portion of the hmrt beoomca suddenly (eme, 
acamnat id Iheaame way hs a bladder full of fluid would hcconie (eose and 
hwd aban fbrciblr Mguee/^x). The sudden pressure eser(ed by (he ventricle 
tW tww ii ata suadenly tense and hard, aided by the closer coo(ac( of (be 

Ti "tlh tbe ebea^waII Iwhich, however, by {(self withou( the hardening 
tonuacliuu wouUl be lOdutficieDt to produce tbe efl^t), gives au itupuM 
ar ihM-lt Intb to the cbcet-nall ajid to the diaphragm, which may he felt 
rmlily both uu (he cheat- wall, and also through the diaifhragiu when tliv 
aUomni i> o|icued and the tini^er iuicrted. If the miidilk-ation of (bo 
tfj^^uaiiti Bph (of w hieb au nhull s|)eak in dttaliug. later on, with the i>uU«), 
ba cardiograph. \k placed on (be spot where tbe impulse it felt u>net 
'. Um \t\KT t* N-trn to be raiwd during tlie HVMute of Ibe ventrtdt^, 
All again a.-< the syttule |ia.-uie9 away, very much aa if it were placed 
lh« heart dirvdly. A Inicing may thun be obtuiiM^l laee Fi^, 77), uf 
ir« aball have to ^-ak more I'ully immediately (itee ^ W.\\. If tbe 
of the lever be placed. ni>t un (hv exact •«>( of (he imimlse, hut ut a 
iHancv from it, (he lever will be >/epreue>' during tbe iyatole. While 
*pnl of ini|iulH- ilM'lf the roniact of the ventricle U incraaacd duriug 
, away fri'in the «(>»( the vi'niricle rctirci from the uhe«l-wull (hy th- 
ilJoD of ita rigbl-to-leli dinnicter), and hence, by the mettinMiuul 
tttackainilt of (be pericardium, dmws the che*t-wall alUr it. 

»n t- 



S 130. 'Hie *OHnd* of the hmrt. \Vli«n the ear u applied La llie vIicbI. 
eiilior cHrectly or hy lueaiis of a, Htetliwcope, two •ounds are Wari), the ftnt 
a cttinfiuraiively loiit;, dull, boomiug snund. ihe second a short, atiarp. *uc)(l«a 
one. Between i\\v liral and eecDud ooundu the interval of l!nie i« wry «liort — 
loo vhort ti> be uiensui-able— Itiit between the fUMond nud the nco«>'<lin^' tint 
pound there i^; a dtstima piiiise. Tlic ^uiidH linv<- lit.-«o liknxsl |« tin* pro- 
niinvifltioTi nf llie sylUlilcs lulili d(l|i, ah thtit the inrdbr cycle, lu far a* the 
«i>iind« nn'. ooncenit-il, iiui^ht Ih* n-piisteDt^cl by: IQbh. iViy, piiiiov. 

Tiir tffouil mund. whlc^h U cbiiri niid ithttrp, prt^cnCii iii> didipulltts. It is 
oiinclilciil ill jiriini of liino wiib the cli»iiiv nf (he wmiliiQur riilve*. and it 
h««nl t<i th(- iKiit lulvHiitn^t uvi^r ihu a^ciiiid righl ooEal carlilafru cl<we to il« 
junction with ihe ftcrniiRi — i. r., at tba imiiit where the imrtic arch niiii«C 
n(^»ri?«r to Ihr ■iirra(«, and to which snimd* ^nvrHt4.t) at th« aoriic orifice 
iTDuld be bent cDndiiclvd. Itii oharuntcn ar« such u WDiitd belong to a 
sound genemtod by memhratie* lik« the semilunar vakte bein>; suddenly 
made tense, and »o thrown ittl» vibrations. It is obscured and altered, or 
replaced by " a murmur." irhcii the semilunar ralvcs arc allecled by diaeaw; 
and may ix nrlilicinlly obliterate!, n murmur taking its place, by pasaing a 
wire down thv arteries and hoolcint; up the auitic valves. There cau be no 
doubt, ill fart, that the second sound is due li> the semilunar valves being 
thrown into vibrations at their sudden closure. The sound heard at the 
■econd right costal caititage is chiefly that f^norated by the aortic valve*, 
and murmurs or other alterations in the sound cauited by chaii^is in the 
aortic valves are beard nioit clearly at this bjmH. But even here ihv sound 
ia nut excluMvely of aoriic ort).;iii, ii>r in certain cases in which the semibinar 
valvm on the two sidea of the heart are not wholly syuchronuuii in aiuion tbe 
»>iund heard here i^ double i " twlu plicated second sound "), one hdiig due to 
the aorta, and miv to iht^ pulmonary artery. Wlien lh« sound is listened to 
DD the lel\ «i<lc of the; sternum at the 3>nme Invel, the pulmonary artcrr is sup- 
|ioecd to have thccbiff sharr In produciii); what is hejird.and changes in tbe 
Bound beard more clearly hem than on the right side are talten as indicati mm 
of mischief in thu milmomiry valves. 

The jir*l Konnri. longtT, duller, and of a more " b'wming " character than 
the oecond, hcartl with grenteKt di'tinctneM nt lh« s)>ot where the cardiac 
impulse is felt, nnwenix many diflicuhin' in the way of a complete explana- 
tion. It is hcanl diKtinctlr when the ehi'^l-wallo are removed. The cardiac 
itnpulse, therefore, can have little or nothing to do with it. In piiint of lime 
It 19 coincident with the >^ystole nf the ventrioUv. and may be heard to the 
greatest advantage al the spot of the cardiac impulse — thai ih to say, at tbe 
plac« where the ventricles come nearest to the snrlace, and to which si>uuds 
generate<l in the ventricle would be best cnuduetHl, 

It ii more closely etjincidcnl with the cloxuiv and eonseipient vibrations of 
the auriculo'Ventriculiir valves than with the entire systole; for, on the one 
hand, it dies away beliirelbeseooud sound begins, whereas, as we shall see, the 
acttinl st-stole lasts nit to, if not beyond, the etosure of the semilunar valvct; 
aihl.oniheotherhaiid, the Hurioulo-ventricular valve ceases to beteiucand to 
vjbrnir tm soon na the contonia of the ventricle are driven out. Thin aue^^tf 
that the sound b caused by the sudden tension of the auriculo-renlncular 
valve*, and thi* riew U !tup|M)rted by the facts that the sound i» obscured, 
altered, or n-plBir«<l by ninruiiim when tbe trimiitpid or miira) valre» are diB> 
eR(e<l, and (hat the r/iund is also altered, or, according tu some ot>M*rven, 
wholly ilonc away wiih, when blood i* [wvenied I'roiu entering the vcn* 
tridee by ligature of the vatiir cava). On the other baml, tlu; sound has Dol 
thai sharp chamclcr which iiue would fxjiis:! in a »)und geiu'ratnl br tbe 
Ttbration of membranes xiicli us the valves in <iiicMiuo, but in its booming 





<nMUiua ratb«r itti|ci;rau a luuflculHr souimI. Further, acconliDK to some 

(mMrvrrv. the Buiitxl, iboucb ■i>iii«wbiit motlifici). mny Blil) l>o hcanl wheu 

ibe Wkc fcins mn (-btiti|KHl an tluil lui IiIchhI <riiti-r> itir v«niric)i*. iiml. imlM'il, 

nor b*! rrcuciiiM^l in the fi'w bviil* aivtm by n iiiiiniiiiMlian vcnlrii'lii nipiily 

rut <iut nf thf living IhmIv 1>r an loraiJoD ciirrivl W- 1 on' tin; miri<-iil<> ven- 

(rirular rin^. Hcni^ tU- view liiu Itcon ndoplctl that tlii* lirvt miiiMl it n 

ntnculRr »i>uii<l. Iti (ljfcii8>iii^' itif ni(MCuUrw>itnd »f aki-l'-lnl musclo (wo 

illOX Wtfwto mi»i>n» l» •li'tniM tlif view ihal I his foiinH nas gwertWd by 

Um rvpoUcd indivi'luitl »iiiiiilp coDtrnctioix nhidi mniif^ iii> ihfl tctaana, Uiil 

Imbcb cormpondm) in lotw to llie nunilx'r tit' lltiiai.- aimjiV ra>t)tnctioii8 rt- 

pMitnl io A woiind, and to ndopt the view thtii ihv s'tiind nna renlty due to a 

n-fvlition of ui)i.-iti>i>l IMMiong oi'ciirniiK in n muscle iluriu^ llie cuiitnujtion. 

Nu«. ibcT«ntricular:^y»(ule isuiidoubleilly a»im|)lec<)ntra<.-tiuii.a prolontp^] 

nmple mntnu-liou, wA a letanua. mtd therefore uii<Ier the old view of the 

Mtiiin- nf a inTwcular soiiiiil. could not pnjiluce such a sound ; but. acceptiug 

tktHihrr vic-w.nnd n^lleclint; how cixuplox must be the eouneof theavHtolic 

mvf iif roll trai.-l ton <iver the twiiied fibres of the ventricle, w« tball nut fiitd 

pnl dirtit'ultv in impiMBiug ibat tliul wave iti capable lu iu pnignn of pro* 

^ariiii; 'ui-h t(<)H.-tili<>iu>i{f uni-'|uiil tMisinns lu luighl give rw to ii"mii««ulitr 

wiimI." and ri>fi»cc|urnltj in n-j^inling ihe fint toanti iii> mninly •>) cmutit. 

A< -iich n vii-w nf Ibe origin of the nound, w« fhould cxptM-'t lo find 

•■ if ihc niUMulnr lihnf, mid w) the luitureof tioiiml d(![ieiidi'iit on 

t!*' .jjniiiuv ■■r Hirid prrwnt in the ventricular nivilivf, and h<nce nn)dilird 

bf t>i,-alur« >if the iiwiil vrinj. nnd *till more hv the total removnl of tlm 

auricir' itifh llip vnlve*. \\V may add ihnl y,v »hi)iitd 

rijrri 111 f^nil it iiii'ititini by the eecnjie of bhiod IVdid the ventricle* into the 

anrriri during; the syBtole iiwlf. Hnil niit,'ht rr^^rd this m eiplaining nhy it 

ifaiaway bc^n* the venini-le ha.-, eeutud to wiilfncl. 

MMTorn*. "i-i'iuK thni the auriculo-venlrieiilar valves innU be thrown into 
■Mm irtuion nl the oiufI of Ihe venlricuhir ^vitiole. vrliJcb. aa we have aeon, 
it ArttloMiJ with eoiisiderBhle raimlily, not far removed at all event* fti>ni 
At npMitr with whicii tfa« teuiilunar valreit are el<iiw<), a rapidliv. ihertr- 
far, npabV of giving rive to ribraiiun> of the valves iideijunte to pmdure 
■ mand. it iadirtii-iilt to <«enpe Ibe condu^imi that the eliiinirc <if thivv ralve* 
■Ml abo irnenttr a tiiund. whieli in ii normally be^tiug heiirl ix mingled 
(a MO* «av wilb tb« Mund of mtitcular origin, allliough tbv car eannot 
dUKt Ibe muiure. 

If we accept lhi> view, thai ibe Miund Lu of itoiible origin, partly " miiBcu- 
Uf." jMrtly " valvular." I»>lh eauiMrn being dependent on tbe tension of the 
tnirteular cavilic*. wf can pt-rhaii* more euity uiitlorstand hon- it i« that 
Ikr wirninl fint round is nl limes to larsriy, indi-cd w« niay say so com- 
(llttly, altered nnd oWrured in disetifes <>l the nuriculn-venlrieiilnr valvea. 

^celhe lett vi-ntriele foimf (Ik- entire tell apes ofthelieiirl. the iiturmiin 
tctther ehnBgesuf tbe lirst si<und heard most diftlinelly at I tie i<|>ot of cardiac 
ittpulw belong to tbe tiiilral vnlve of itie lel\ ventriele. Monnunt genemteil 
b the tricii^Did vatve of the riphi ventiicle tirv beard wore dbtinctJy In th« 
wdiu line oelow the end of ibe Kemuui. 

Kuiloenrtiiae PrtMUre. 


f m. Sinee lh« heart oxbis for i1m> pur|iaM of vxerling presMire on the 
Utni within its rat-ilie*. hv which premurc (be eirenlntion of the blood is 
(it«t(d. the etudv of the e^anicters of this rndocardiae pressure poawsMa 
fital intvtrsl. t'nfonunately. ihe iibHTvalion of thia pressure la stieoded 



witli );TPat r]ifl]ciilli«i. The ordinary mercury iiianr>iueltir wliicli m on user 
ill studying tlio prcmiri? in tlic iirlerica fails uit wheu applitN) ui ilie lieart. 
It ti true tliut a loit^* canula, or lube open ai (he «Dfl, lillad vriili sorliurn 
carbonate solutiiii. may Iw inirixiuccd into the jujtular vein anil wi Kliniiefl 
dnno iuto eiiber the riglil aurit-le ur ihe ri]j|ii venirii^le, or may 1h« iiimilarly 
Intrniluoo'] into Ibe (.-aroiid artm* and with <-nrf ulipjied dowu thnut){li liii' 
oortn, put the soniilunar valves, icii') Iho left vt^ilnrle, and baviiig been 
tbua liilroduued may, like the ordinary caoula uned in studying arU-nal 

1>reururc ($ ll.O), be broiigbt inui c()iiueci)i>ii with a niert-ury mnnoinoteT. 
n [biji way, nit in the ca^ of an arlury, a prapbic rtniord may uc 'ibtiiinvd o( 
tbu chnnjjcs of |irc«ure lakiiijc {)lace in thither of the nb»vo thret cavitJM. 
But tile diniiges in llic vcDlririilar carici«< are m grvat aint raptd, that the 
inertia of iht: mrrcurv, an evil in tlw cn»o of an iirtery, mmcs w) Iar),'*ly into 
piny that ihc curve (l(Hcribvd by the flout on tlio mercury is far from beiag 
ail accurate n-cord of tbc chaTigcit of prcsMire in llic cavity. 

The mcrt-iiry nmiionwlcr may. htiwcvcr, be wade to yicfd vnliialde reeiill* 
by ad opt in (I the ingenious conirivanc* of convening the ordinary mnnomei«r 
iolo u niiixiruuin or a minimum inlrument. 

Tile priiKi|>te of tbe maxiniuu mnnaineler, F\g. 72, uonitiiiO in (lie inlroduetion 
into ttii; tulie leading fVoni ibe heart to tli<.> mercury' eoluntn, <i( n (mudrficd cap- 
aod'ball) valve, opening, like tlic aortic aeaiiliiiiar valve«, eu^ly frani tbe hcan. 


Till! MtituiH Uxaeanna or 0*u> mid <".i i^ 

At ' ■ contwoUMi U auili; sriih Ihcliil* iMdlni lo tbe hMrC Wbrn the •pn;v<UBp t Ic eioavd, 
Ibt mlTB r (•mil* liibi nrlluii, *n(l llio luilrumcnl. ID llio poililon of Ui* rain ilwun la tb* l^nk 
l> a iMxlmiim nutnoniitUf, lly rvivnliiii iIhi illnicilloii of t li !• niii>«n«(1 Inlii a nlnlmum nuu»- 
Omrtn. Wliirn t Imptnad, llic (arlHUims uf |<r«Mun ■» miiitcJw) Blong a. nod Uie UMmpRil Uioi 
Mtt llfc* an •mil iiui] iiuuiOQiDler. 

bat cloMDg firmly nhen iliiid atlttmptc t» return to the heart. Tbe liighmt pres- 
Hire it that which dritra Ihe lungect column of fluid Tiwtt the voire, raining the 
mercury ouluma lo a currtHpoiiding height. Since thii culumn, oan? the 
valve, cannot return, the mercury reinaiDs at the height lo whiuh It niu raised 
hy it anil tbu> iccotd- the Biaximum preanurc By r«ver«ing the direction of the 
lairo, tile manometer i* convert<<d from a maximum into a minimum instrumeiit. 

TTw mnximum manometer applied to the cavity of either ventricle or of 
tbe right auricle, gives a rcoorJ of the highest pressure reached within thiit 


nrliT, ami thr niinitiium mauoincler aiinilnrly iliowtt the hiweu prvwure 
utrifi, (liiriDb' il>c lime tltiii lbs iiuttrtiiuetil in np(ilieil. 

TWni««tntuiii iTi&ii»met<>r itiusemployMJ tliow.-rtlint the maxitnum jiroi- 
HTMO llic Uti vciilriclr t> (Iminctir (^reurcr thuu Itie mcsii urewiuK in the 
MUfllifi ortlitiBry ntPriniry niMKHDcicr ImviD); previiiunly giveu lti« [hita- 
dunl rpMili. due In tlx' ittenia or Ihf iiH>n-ury, l!int U)C iii«nn jin^Muro ta 
ibt IrA vtintrkl^ iiiit,'lit \tf li-w iIirii in lli<- iionn ^ thut llir nnixiinimi jiro- 
■itin Um Hfcht TOiilrii-l<- ii Ir^t ihiiii in lh<' left, iiii'l ill lliu right nurivlc b 
4111 Imil la Uivdofc. lor «'xiuii|>lc, the iiri-Miirp in ihr left vciiiridi* nwcbM 
luiimum nrnlxiiil 140 iiiiii. : iiii'riiiryi, in ihv right vciilricio of about 60 
Mi.uul in iIh' rii^ht aiirii'h- ol'iilimit 'i^O mm. 

Hal lb* chief inimMt ntlnchi^ in the miiiiiniim (irvH^iirr oWrvnl ; fur ihfl 
oiiiMiiu ttwiKHnotfr nv>r>l^ ii uryliif prcmiirc? in (he cAvilieaul'the hnut— 
iL t. ibmw tbst tbe prwMirt- in ihi-m mny fail bclxn thtit of ihc iitmmpherc. 
Tbnio lb* IcA WDtrklp (iif thi- d<%'i n minimum |irt»<ure v.iTviii}; from — 
Ut* — 20 IBID. ttMy hv rcncbiil, tin- minimum of thv ri|;hl ventricle being 
lh«B — 17 to — 16 nim„ iihi) uf Ihe righl niirii-Ie from — 12 to — IT mm? 
hitof this dimiDUtion of prCMiire in the ctirdiav cat-itiee luuy be due, as 
•ill b* I'Xplnined in « Inter part of tliie trurk. \'i the iui>iratiou of lh« (borax 
ii ite ft«pir«l<>ry movenM-nt*. Bill even wlieii Ui« tlionix i» opened, and 
Biiicnl mpintitw kept up. uniter which circuinslaDcn do such mpirati'm 
ubi plu«, a ncftalive pn'&Hire i^ «till uhwrved, the ptvasure in the left veii- 
trirlr Jllll tinkiiiK o^ l<"^' *^ — '^^ t^'Ri- Now, what ibe instrument uctuallv 
ik^iis thai at ituoie lime or other during tlie number uf bentM which took 
pbf* while tbe instrument wu applied i and thes« mar lutw been very few) 
Ihf fMMUR In tbe ventricle lonk »o many mm Ih-Iow thatof tbeatmoflphere 
nhi* mTTBlivf |>irM>iin.- is olimrved when the heart iti Wating nuiti- regu- 
,nc\t U-nt Wing exactiv like iho wlhrre, we may infer that a nt.-gativ« 
Of* im-un at s»nn- p<!ri<Hl or lahcr of ench canliiu' i-vflo. Itut tho 
roiiK-ni ■ibvlinii'ly givcd ii* no inl'orminion w to the exact phaec of the 
hwiB iihirh the ncg"tive pnwiiri' iM-curv; to thu point Its wvll M to tho 
iaaurtnnrr of (hi> iii-gntiTe jircsurr "c jhtill return pnwently, 

\\M The diHiruIlir* duo to tlic iiicriia of the mercury may he obviated 
kf (ilcipting the nx'lhixj of Chauveiiii iinil Marvy which cuii*i<t« in inti*i>- 
Htiif in ■ largo aniittiil iucb as a horce, through a bloodvcaeel into a cavity 
Wlhr hnirl, a tulw ending in nn olu#lie bag i t'ig. 7-t, A ) fashioned »i>inclhing 
Kk( • wmimI, both tulw and )>ag Ixting tilled nith air, and the tube being 
naotcMd wiih a recording "inmbuiir." 

A taW of appropriate corvniurr. A. A, Fig. 73. la ftimioheil at ita and with on 
*laiti«ba]C or ''ani^utla" -i. Whi-n it ii ili-nirrd to cxplurc nimultaneoualy Uotli 
diritl* and veninele, the mund i- I'liniinhed vith two ninpulla- with tiro amall 
•tMlr l>*g*> on« at the extreme end and the other at such a diatance that when 
tbf fannvr u within thr cavity of the ventricle tbe latter i« in the cavity of the 
•■kir, Huefa an iaatraiDOOt iaijiokenof ann ''cardiac souad." Knrh "aiupolla" 
mnicam by a aeporate air-tiglu tulw with an air-tight tambour (V'\g '-i, U) 
'»cb a levrr rml*. mi thai aiijr iiri-^ure on the aiiipulla b cuiuinuiiical«(l to 
irity of ilH re>t|H<rtiTe tiiinbiiur, the lever of which is raiwd in jfojiortloR. 
two anpullB> are iiaeit thr writin); |»'iniit of biith leven arc brought to bnr 
I tmmt fvconling furfaee pxiictly niidrracstli each irther. The tobe U core- 
'iMroHarei) through the right j'l^iilar veta into the rijchi side nt the heart 
lb* hrviT t ventricular I ani|>iilla lo (iiitly \n the cavity ol' the litcht ventriola, 
I tcawrijarntly the UJ>i>«r (nurivulnr) ani|>ul1a in the cavity oflhc riirht aurici*. 
(loanraihl prvTi-ureon Mtlicr aiu|iullri Ibrn cauw iniweiniMili'nriliv eurm|H>i>diaf[ 
When tlir preaMre, fur instaoce, on the aiupulla ia the aurkle in iDcroaaeJ, 

' n^ kanikan am In t* nail tuvt mnvlf a> Innaari i irhich kin tn^ olBcnvd. aad OM ai 
Hp>4««n Itrm ■ tus« ai^ln of n**a 



With grwii (liffimltioB, The onlmary m«rcury muiionieter which \a m tiBemT 
in ituih'ing tlu- pn^^iine iu the artvrie* failH us wbcu npjiHoil in iho heart. 
It i« tnir ihsl II long cuiiiila. or lube open iit the eiiil, filkd with fto^lium 
citrWiintn :i'>hili<in, may bi: iiurniliicuil iutu the ju)culnr vein hdiI ita vlifiped 
(l>>vrn iiil'> i^lliT i\\v right nnricle or the rl^ht vtmtHt'lc, or may be i>iiailiirij 
iuir^xbiccul tnli) the rnmtii] tirt«ry lun) vtiln I'ltn* iilipTieil Hnti'ti tlirnugh th« 
sortn, piwt the scniiltiniir vnlvM, into the \ett vcntru'lo, ami linviag httn 
thtXi intro<)i]CiC<) mny, like llie unlinnry miiiiln iiwrl in ■lintying nrlcruil 
pmaon ($ lI-'>), be brought into (wnnt'ctinn with ■ roemirv minKimcter. 
In this wity, nf in tlio caw; of nn itrtcry, ii ^riipbir n^cord niny be obtninetl of 
the changes of premure taking pUiM in cither nf tlic nbor<i tbr«e cavitiM. 
Dili the chtiiige» in the ventricn]:ir caviliiM nrc to gnwl nnd rapid, thnt the 
inertia of the mercurr, nn evil in the ctuc of nn artory, cnniM m largn^ly into 
play that the curv« describod by the float ou the mercury is far fruni being 
nu accurate reoord of the changes of promire in the cavity. 

The mcrciirr mnnoinel^T niay, howerer, be made to yield vabiable mulls 
by sdoptiiii; the iiigonioUB contrivance of converting the oritinary inauometer 
into a manioiuio or a minimiiin iDtriimeat. 

The principle of the maxiniuin tnniKimvler, t'ig. 7:2. conamts in Lbe introdiietioa 
into the tulip ImdinK fnim tlie heart to the imrrcury column, uf a (mwlilieil cnjr- 
anil-bnll) valve, openlug. like the aortic Miniluuur vatvea. easily from the h«an, 

no. Ii 

TiiK HiiiKiH UutoHsm or OvLis «)n> oivix 

At » • oaMiecQon l> awlu Miili tlie lulio laullnclQ Ibehoin. Wlicn the lercixlapiii * l« Clowfl. 
IktnlrofoiiMliitaBrtloii.anillliD limlruiiiviil, Iii iliv innlUuu of lliu nlr* tltaan la ItW SfUl^ 
It • iin ii n« u ni muunneUr, Ur nnnliis ilii- dircciloii of i' u l> convcrici) iMu ■ rnlalmwin nuuk- 
DiBiAor. Wlu-ii tlio^wsad, Ibe vulnUuui ur iircatiirc aru copiDfvd almif u. sad Uic ttuUanunt Uwn 
Mb Ilk* nn ontlEiMT aananKMr. 

but cloalng flriair wlien fluid atlcnpt* to return tn tlio hearL The liighott praa- 
•ure is tliai whicli drive* the longeat column of Ruii! {>iuit the vaWc, raiting tha 
mercury L'olumn to a corrMponiling height. Since ibu column, oncv pa«( thB 
valve, cnnimt return, the mercury remalas at the heiglii to which It win raised 
liy it ant) iUuh reconin llie iimviiiiuin prMxure, lly reversing the direccitin of the 
valve, the munoineter ia converted from a maximum into a minimum iiittiuaienU 

The iDBiciinum manamelvr applied to the cavity of cither vcDlriele or of 
ibe right auricle, gives a record of iho higbi^<t pKuiire renchod within thni 



artr, uxl th<> tniiiiiiiuiii itiAiioincipr iiiinilnrly >li'>«r8 tb« lowMt |)r*mira 
imHwI, durinj; iltc tiiii« tKiit ili« iti*tritn>cnl W opplitvi. 

Thr mkiiriiuiii maiioiRftiT iIiih mi)|»I«v«<I dinwrthat ihv mitximttni ]>rM- 
■I* lu the toA v4-nirii'l« » >lt»iincllj grcnlcr Ihno Iho menn prcmure in tht 
■■rtiilbr onltnan' mvreury iiiniuk racier Iinvinc previously giveii ihe |iuni- 
iniai malt, due to iIm- inonia uf lh« nier<-ury, that the mcnn prcesurc in 
(blifl mitmte nii^'lil Ix- leiii' ilmn in lli<> uorta'. thnt ihe niniiimim proft- 
Mnin Ihv ri^l)t retilrirle b tfiSB tfawi in iW l«ft. iiod in ihe H^ht auricle is 
Mill Urn. In (tie dot;, fur exiiiDpl«, the pressure in ttie left \-eiilriele reiichoa 
latiimiiin 'ifatratit 1-10 mm. I nicreury), in the rij^lit Teiitricie of nbout 60 
M^ Aiid Id iIw Tight niirit'le of nbout 'i<) mtn. 

Dm the rfaief inlervKi Htlncltfe to llie niiiiiiiiiiiii prwaiire uWrved ; for lh« 
afainsn nanonieter nsH>rtl' u ne^iliit presgitre in the eavilieanftiie liean— 
i(L.«bm> lliAt ihe pre*«iir« in l\wm may fall beluu ijjitt uf tli« atmiupli«re. 
Tbiln Uie left ventrifle (of iIm* ci-ifii n oiiuiiiiiitn |iivsHurc varyiiijr from — 
VlU — 20 IDID. (UHT be reuelivit, l)i« iiiiiiiiitiim of th<^ ri|;lit v«D(riel« beinjr 
fioa — 17 lo — 16 mm.. ainl uf ilw HkIiI auHi-le from — 12 m — 1" mm. 
E^nof Ibi* ilimiDUtion nf ]ir«Biir« in the ciinline i^vitin may he iluc, a* 
■til W npliUDetl iD a ialer parioniiiu worlc.t^ the ttamralioti (ij'th« thomx 
ii lla lOfiiratory nxivinteni*. Bin uvea when iht' thorax i* upeiieil, itiid 
arliftfial n>pinil>o<i kv|K up. under whieli cin-iiini'runi«« no i>iieh anpiration 
tabi place, a n«^tiv*- pivwurv i> riill •iImitv<'<I, the pri'miirc in the lefl vcn- 
iriflr«lill linking n» Ion m» — 'li mm, Now, whiil the in»tritmrnt actiiiillv 
abuii i* that at i>om<- linn- or other Htiriuji tlio nnnibiT nf beittx whii'h took 
plat* vliila thv iiutrunirnl wan npplir<l i iind ihive ninr haw bc«n very lew) 
ihifniiw in the v«nlrid<t!uiMkf>o mnnr mm In-low ihiil of tb<^ atmnfphvrv 
9btn: tbi- ncftnlive tirmxtiri' in iilui<rvi-d when the heart a ln-ntinj; <|iiile re^u. 
Itflt, i-arh iM-ut being exnelly like tlie i>lher«. we miiy infer thnt a ne|;Dlive 
«tv iMxiirf at Kidie period or olber of eaeh eardiac cycle. Itut tlw 
DSiTDt obviously f,'ivefi u* nn information as to the exact phiLse of ihfl 

til whkh the oeKalive pre»ure ncenr»i (o ihia pojol as well as (n the 
on if ihis ne^rative preaaure we bHaII returD prvaeotly. 

I US. the dilficiilliefi due to the inertia uf ihe oKrcurr may bo obviated 
by iiloptlax the mcthitd of Cliuiiveiiu lujil Marer wliit-h conttiiU in iutro- 
Mrip^ in a iarye animal such as a horse. tbrou([h a bloodresMl into a cavity 
«ftbe benrl, a tube ending in an ehutii- Imik ' ^ig- 78, A> fashioncit something 
likt a miiixl, tioih iul>e and liaj; beiny filled with air, imd the tuln; being 
mmtcu^ «ilh a recordinif "lumWur." 

) labe of siifiropriHle curvature, A. ft, Pip. T^, is lbrn!«Iied at its end with an 
klisj; !•! '■aBipiilln'-r, Wlifn it i« il.*ir(.I lo explore simultaneously botli 
it aitil Tvfiirlrli', (lii> Hiund i* riiiiii>hi-il with two ninpu11«> with two small 
*(aulc iMfi*. one at the extreme cnil Hiiil the other SI inch a ilblancr tliat when 
ibc f'TTRpr ta within Ihe i-Mviiy of the ventrii-le the latter is in the cavity of the 
Mr- I IB iaitriiuient iii*iinkenora«a "csr<lia<: sound.'' Each "ampulla" 

(DC. by a MjianiU' iiir lijilit tulie vith an air-tiKht tamUiur (Fijc 7-E, D) 

•« •Uifli a Ii'K-r r<Bts, vi ihul uny ptnaure on the ampulla ii oJtumuaii.'itli'il lo 
(br (arhy nf its resiiective la'ulH>nr, the lever of irhli-'h ii raittd in profiortion. 
I iwp aoipullie are usi-il ttit- writing points of botb levers sre brought to bear 
Fsamr reeurdinjt >urli*i'i' rinctly underneath cacli other. The tube t* nre- 
'{fliraduatol ihroueh the ri|{hl jiiRutsr vein Into the riitht siilc of tbr heart 
IllMkrwer {ventiicularl an)]Millii is (nirly hi the Cavity of the richi renlrU-ts^ 
iMSMnawtl^ the upfier tauricuhkrl ampulla in the cavity of the riclit suriclv. 
■BBtof piv«uroon either ampulla then caiiMt inovemeots of the c«rrr«pi>ii'lina 
WbMi the prcwure. Tor inslsace. uniboiunpullainUioaorickiit incmumT 

*tb— WMat t wamobs nxMlitrnrt nmlv >• lawaiMai aUoh Imv* )■«■ u trvsJ. and bMh 
<—Wihwwa a— a toiye nus U w al ■— 




tfa« Hiiricolar l«vtr i* rniif il and drocribpa on Ui« r«corcliii|{ nirikec u ■«ern<linK 
CDivr: Klirn Ilic |iirsiiiirc ii liik«n ofl' Ihe curve tl«»cen<la; and to alio ir lib die 
T* lit rifle. 

The "iKiiind'' miiy In n iiimilnr munnvr he rpiiHUr iitlmilurei] ihrougti ihp 
carotid nrivn- itilo tliv /^ vfntririr and the cbunKn ukiiig pinve in ihui chnml; 
a1«> ciplotrd. 





MiMT** TAaaiii'K «'iTii Cakdi*c Mi'miv 

A- A >Liniile isTtllAP totiurl viicli lu Enaf be lihd Ibr cxplormUoti ut llw Itft nfU'iclo. Itw iort3£m 
• olltii' iiuii'illn >1 llii> villi i* t>( III! 11 liiiI!ii'itiM>cr, ttn>ti'l)vil uiut aii ii|i*ii fnniwuiirk iitlli imrlnUle 
nppiflti gljuTciinit bt'luiv. ITii: long iu1« ^ wrvn lo [iitnxliici' 11 Into ihu cavllf Btilcli It liitBlnd 

R Tilt utnlwiii. I'lio cnrUl cliainlii'r m In <nrigiv<l 111 mi nli-tlghl iiiBiiiicr irilh Ihr IndU-mM** 
c, bcarLiijE & ihlii Qicliil pUle n'lu vlilcli h atlvh^ Hit Itvcr I iiio%inie *>" the bliict A, Tbe itlHikB 
UuiUiiir iMii W iiliicol liy incmiiof Ihc i.-l*iii|ifViil*ii)' lieidOliiu Itiu iii'ilglil r. Tlin lii'Ua-nililivt 
liibr rxtvn lociiiiiivot Ihr Inii.'rl'itortliounit'iiirvltiipr n1(b ihoarltyornivuminillii uf.t or mil h 
Mnr olhoi CBVlir. Siipiitnliii! liini ilio tube ( vttn connci'lril * lUi b. kiiy jiremun; «■»(■«•! on ^ wuuld 
CMi« Itw >u4(«f tbo Umlnurlu rite anil Uia point af lti« Ivvvr woulil b» jirnjiutllciiiiild}' mliwl. 

WIk'ii lliLi inHtniRK'nl ia iipplir-'I (o tliv right ntiriclo iin<t vrntriclr' Knn« 
ituch rvcori) t* uliiaiiic^l nil ihiit i^liown iii Fig, 7 1, whrrc the ui)p«r curve i» t 
trnciiig Itikrn I'nim ihc right iiiiriclc Bin! the Inwrr ciirvo from the right 
vciilriclc of Iho hi,ir»«.'. Iwih curve* liiJHg tJiki'ii simultaneously on the smne 

In ihno curvu lliv tisc^ uf tho lever indicatefl prcwure exerlcd upoD the 
corrciwiiding aniiniUii. niid the upper curvo from the right niiriclo shon-s 
tbp sudden bripf |>rcs<iir<' ib) pxcrlcd by the ■uddcn and brief auricular 
syetole. The lower curve froin the righl ventricle ^howit ihnt the preanire 
exerted by Ihe veutriciilar sVfilule beginii nituoat immedistely after the auricu- 
lar BVfllole. increflBee very rapidly indeed, so that the lever risee in alniixt • 
elraight line up lu c, is coiiliuued lor eoiue ounaidernblfi time, ami then 
ftlls very rapidly lo reaoh the base line. Itul it may be duubted wlwtber 
ifae iDBlruineut can be tnuted lo tell much more than tbio. The prasure 
noorded by each lever is the pressure exerted on the imipuUa, and ihb 
nay coniinue lo be exertc<l after all hlmiil hm \ttren i)ii><-harged from 
cavity, the nulls of the emptied ca^nly eliieing round and prci«iiij[ un 
amiMilla. Uut. iia Me ohall presently M-e. it j^ of gniit inien«t to i)e<ermiiM<r 
Dot only the furcu and duration of the prevaure exerted by ibe ventricular 

Ttric n«A«T. 

Flo- -I 

,but alio wbetber or do tlie Gbrea continue cmlriict^d iiti<l i-x*'rlitig 
■n for RD npprvcinble lime after ibe blooil has been force<l oui o( the 
miir. Tb« figure. nii>reover, it i>eeil banlly 
WaiM. dwa uot by ilftclf tfive any iRfurtnu- 
liga ■• lo tbe relative ainuuiils of pivwure «s- 
ttbd tw the auricle and veiitrid« rMpeclively. 
liihorarve ilie auricular lever nixa almiit 
Ufwhifth a* lli« ventricular lever; Iml vn^ 
■Ml not luAr ftuni tliw ibat the aurit-iiUr 
<nkc ii half aa »Iroug ut the veatrioilar 
Asko; tba fomtcr in amogoH mi ux !•> n»>v>- 
nnth BDre nawlily, to be much more friivicivf 
IIm the lalliT. The iiwiruiiKritt. it i* [rui-. 
iMf be cspcrinienlally gra<liiu(r-i], ami ninv 
ikil be u(«d li'i ilctrnuiiti; lln' nclunl ■ramitil 
rfuraailte; but fur ihU jMirjirHO if iiot uhnlly 
■mclor^. W«> may a<l<] dial ihi.' irrt'^u- 
hMn Men on thu wiitnnilnr vurvc ilun'iig 
(b mtriralnr «yMoI«. ami un the nuriculnr 
nitr Bt itic xiini« limv, hiivu givi-ii ri»c la 
fluuh iletiate, uni] ncnl n«t be ilitcuwvil here. 
0> die nbole, thv tnethod, though useful for 

Jlnug a gnif>liie T>ew of ihe fcrira of eveniB nithin the canllar cavilira 
ung a canlioc' cycle, the «hort auricular promure. the long* eon tinned ven* 
tncaltf fn^nn, lafling nearly half the nholi- period, atid the $iibHx|UGnt 

KlniiT \i ( ■ ■■ ■ ■■ r. I, r iinifui! or 
tat. Boi^' uii anil 



n-a*a* or bDociuiuc |-uo*uaa; Pxia Ltrr Vixtatcu or tmo. 
Xa<tnratr«mllkC.II,*liHim>Mil}liniUuN. boul. Tlw Mlvn tu tM* aa^ IM fiirMKaiaa 



d«Keiil lit' tlie k-ver i.'linii^v» In rnli'. liMimiiinj; Inw rapid, c<>riv«pou<l' 

end of ilie oultltiu iVom tht- vt-iitriHc ; )>iit thii> m imt n-rUiiii. iind. in>k>c<l, 

Um exacl internrelHtkin ur Ihin pnn nf ih<- nirro i« r«i>i>cislly difficult. 

Ute oeape rrum the vuniricl^ iw mptd nnd fi^rciUlf ; tht^ rtnw c<'ii>cs fiid- 
4001}". Hence, a» wc hnvc ntrr«ily »iati-d, S I'J". nwinp Ui the mlutan of 
bloml teudiiif; U> move "n bv virtup nf im iiiprlin iillcr the pr'iiTlling force 
IiMCMMhI ti> net, n ticentivi- ;>rx«»iire m»kc» its appcuninre bchinil the column 
of blrxKl ilWharKfil friini tlic vcnlricte. iind us eoon its the culiiinii is Indgvil 
ill till- iKirlu IchiIk |i> ji irllpx toward the ventride. Thii retliix wnuld nf 
ilH-lf liiivo llic cflbct of oliwiitg ihc vnlves even vrere the tiurtn ii rigid lube. 
But the iiortn i« extensible and elnstic and the efl^(-l« of ihc movement uf 
the column of fluid arc combined with the effecls of the movement of lb* 
trterial nails ; the clastic action of the arterial n-alU, in a manner nhioh "« 
shall di«cim later on in dealing with the pulM>, also leads to a reflux. It lias 
been iirgeil that the reflux due to the negative pmnin of tbe were move- 
tnent of the column of blood being more rapid, occurs independently of uixl 
earlier than the reflux due to the elastic recoil, the former closing the valves, 
the latter securin;; iheir complete closure. Be thin a<> or no the valves are 
probably clo^d almost imme<]iately after llie escape of the ventricular ma- 
tents, though observers nre um afreet) upon this |*tiint. some urging that the 
valves are not closed until so late a period as the puint rf, just tu. relaxaiioa 
U about to beigin. In the curves we are now wmsiileriug, n notch, futluwcd 
by a t4w, or at least a more ur less abrupt diunge in the course of the curve 
■te'. is aointiinics observed in that narlnf the curve nhich intervenes between 
tJio int lurge Tvfe and ibe Rnnt sudden fall : atitl thi.s secondary rise has btt.-» 
taken to indii'ate the oloaiire of the nemilunnr viilvc:>. Soraetimcxi tw<> such 
notch (V and iH-aksnreaeen, and theni-ciirn'ni!*- nf the two ha* )>c«n attributed 
to a want nl yyncbmniym in cliv dunure <>f the pulmonAr}- and aortic semi- 
lunar valve«. the tatter closlnj^ some little lime before the former. But it is 
by no means clear that these notches and peaks are thus due to the closure 
of the valves: they may pomihiy have another origin, they arc not alwaya 
pmeiit, and indeed it dues not seom certain thai the chisiug of the valves 
should necessarily make an impress on the ventricular curve. 

^ 134. In the |)erf<irruanee of the ventricle then <aml wliat has been said 
of the led ventricle applia> also ti> the right ventricle) there appear to be 
four stages : 

1. A mpid"gelting u)i" of pressure within the ventricle, all the valves 
being as yet cli>sed: this continues until the pressure wiihiu the veutricle, 
becoming j^rcaier than that in the aorta. thn>w* oiwn the aortic valves. 

'2. The <vcn|ie of the contents of the ventricle into the aorta, the oontrac- 
tion« of the ventricular walls still continuing. 

:!. Further mninletiunce of the contraction for some little time after the 
main body, at all events, of the cuntenLx bare paawd th« aortic valvos; by 
this the compktc emptying of the ventricle Miaiut nasured. 

4. f^ddcn and rapid rvTiiXBtion of the ventricular walls. 

These four events together nmko up a large |K>rlion, and tu « quickly 
be«ling heart the greater portion, of the wholo cardiac cTcle. 

Meanwhile, that ts during the lime froin t/' to u. blood has been flowing 
from the j^reat veins into the anricio : during the interval from h' to d Douo 
of ihifl can pass into the ventricle since this is slill contracte<l. but with th« 
oomniencenient of relaxation fnmi >' onward there is no longer any obstacle; 
on the oonlrary, as ue shall see, an induc«menl for the blood to pass from 
the auricle into the vciilritle. 

For n brief time, as we have seen, there is probably an unbroken flow 
from the great veins (pulmonary or vens cavic) tbroujjb the auricle into Die 

ide, lt»diii){ ii> m Mvftdy l>ui aliglit in««aM of tlie frouMo-back diam* 

bi > »Jt]cht |>r<i«ure of ibe a]iex on ibe cbc«t-inill, nml in a xlight 

bicrtaM iir inim-vriiiriciilar ]>rcMur«, cmiemlljr Hlmnu in the curve nr the 

riovljr bmtlng Itiwrt i>f tlii' bon>e(Fiy. li). lu Pig. 76 the suilili-n riw i!uG 

luthv ventrkular »p(i}lo im precwk^H by a riw fc luIlow«d hfn (all. forming 

Ibo*. a* It wen', a *lii>iil<k-r im tb« curve. ThU hiw l»p<in iiil('r|>rolixl u» inili- 

(aitag tbr aliarj) Iriinnii-nt aiirkolnr kvhKiU-; tlic Huildvii iiijci-tioii of llt« 

aaricular coDti-uia into tlic v<intridi- iiirn.-iiv:s tbo fronl'lo-back diatn«tcT of 

tU natriclc, anil tlw iiiuiiiuiiUini >'!' ib^ rtipiil •tr»kv being coneidcrablo, tbo 

Uvn i* in MU-ti ca«e carriod Um> far furwar^f, mt tlinl tbc riM u Ibllowcd hy a 

bU. pTQituciag a notch. A fimilnr thougli eomcnhat diflcrvnt shoulder is 

■Iv ttm tn ibn cnnliogntra Fig. 77. In the curve of ventrimlar |)reMUT« 

tabs by moaiut of the cardiac Miind (Fig. 74) iheni it a rituilar leinpnniiiT 

iHraM A^ in the vi>otHi.iilar prrssiire coincident nith the auricular iitroke o, 

•ad in i1m> " pi<U)U " pressure curve of lli« rapidly beating heart (Fin-T.i.A) 

that b a ninilar thotilder 6 Jti»l preceding the ti^ of the veotriculur systole. 

Tk amtirnf; of ibe lasl curve is, bovrever. doubtful, for io tbc siniihtr curve 

otiht iBon alowly beating h«art (Fi^. 75, B) it occun inimediuiL-ly al\er ibe 

niniliiin of ihe ventricle, eume lime ii^lore the nccurrt-nee of iIil- ntiriciiiar 

vnlola. aod )<■ tDany mrven takvti by ih« tuime methixi h ahttent uluigeiber. 

m ftact nuiininK. tberefure. of lli« tibouldvr b in the other curvea niuni l>e 

Mstiinwni iindn-ided. 

t lis. \V>- liiiV4' Mlill «i coimider tbo DC)(ativo prcMure abonii br chc mini- 
■an nanomi-U'r. Thi> iuHlrumeitt, an we have Mid, merely •hnws that the 
fnmnn in the virntridc (nr aurtcle) beoumea oegativu at ft^mo pbaae or Other 
af the canliac cycle, Ixit ilovx nni tell ui Ln which pbaie it occur*. 

}i<im there are tno iriiv> in which irucli a negative prwduro might nriginata. 
Id Iha flni place, a» ne have just Hxn, u negative prewurc makcM its npjwar- 
aaea in the rear of Ibc colomn of blrHHl driven from the ventricle into ihe 
aota with great suddenness and rapidity. But this negative pressure, ns we 
hiTt ako Mxa, fulluws the column iaio the aorta ]>a«t llic semilunar valves, 
aad in pan ai all event* determine* the closure of tbc semilunar tnlves- 
Utwe if thifl i> tbc negative prrasurc which the minimum manometer 
fteanlik it ouaht tn I>e abonn not only wlicn the end of tbc tube conueetetl 
vU ibo nuuiuiueter is in the cavity of the ventricle, but uIm when the tube 
M •Upfwd nut of iJie ventricle just {>asl the semiluuar valves. W'bttu ibe 
tA»t Bowewr, la in the latter eitiialiun tbe manometer does not shuu' the 
«Me Bisrked negative pmMire that it does when Ihe tube is in the vetilricle; 
(he nmaiirr pnMure which (lecura in the aorta at each beat h iusuffideiit to 
mdace Mich an elferl on tbe minimum nianoineier lu is produced when the 
B«ot i* in the \-enirieIe. iieucv we infer tiiat tbe uegaiive prewute 
by tlw minimum uiaiioineler u not produivd in tbi.i nny. ^^ e may, 
rmr, outidude that tbi; .'«niiltinar vah-ee are cloHeil In-fore thi* negntive 
\n oinkta ita ap|wanuice in tlie ventricle; otlK-rnis-, iiowever pmiluivd, 
il wiMild l>e traikMnittcd from tbe interior of tbe veutricio through the upcii 
talm to the root of tbc aorta lieyond. 

But tliere is another event which might give ri« to a n»ativc pfwsure. 
Tha rrlaxation of the vetilricular walU in, a« lite ciirvcH (Pigx. 7-^, 76, 77) 
4feir, a rajnd prooeas, something (piile dinlincl frMn tbe mcro tilling gf tho 
iwtrirulnr cavitica with hlooi) from tbc anrieteai and, though cumo bava 
4ijii Hd III the view, it tniiy be urged tluit lhi:i return of the ventricle from 
in mklnuled (and empUeil) oindilinn to itM noroiul form wmild devi-iop a 
■^aiin> praauro. This return io proiMbly niniplv llw total mult of the 
mrs of each Hbre or tibre cell to it# nniurul comfitiou, tlmiigb some have 
ojgw) that the extra quantity of blood thrown into tbo ooro&ary artrrita at 




the E}-slot(> help* to anfoUi the ventricles aoinoirbat in ibc wnv ihnt fliiM 
(Irivpii Wlweeo tlie tvo walls of a. clou ble-wal led c»1Iiijjm>(1 balfur mip vrill 
unl'tilil ii^ 

Ai'cepuug the return of the veutricle« to their nurmst form ii> ibi* cnuM 
of ihe lu-eiiiive prawure (au<l it miiy l)<> rerunrkfil thni Ihi; rpliirn of lb« 
thick-v>alleil \etl veDtricle oaturatly exerts n K<^riiit-r ni.-gutiv« [irowtin- than 
the tbiii-K'uIled right ventricle), it in itbvioiis that tJie iieguiivf jinittnirD vill 
aBrixt the circulation by Duckinjc the hlmn) which hiw mMiiiitbilr li«eii acca- 
niiilated in the aiirli-le iVom that cavity iiifi the ventri(!1l^, the aiiriiiilo vcti- 
trietilar valvun easily )(iv)iix way. At ihf Hanie timf^ thi« vcrv flow from the 
auTicli- will at once put an end lii thi^ UL*gative prvwurp, which nbvioui^lv can 
Ih: i)f brief (luratiun •mir. It may further bi* urgvd iu :iup|>ort of this vtow, 
thai evGii when l\w thorax in i)p<-Heil, *o that thi; nt^piralorv niovemcnta caa 
ii(> loii^r act lounri) producing a iiegiiliv« nrewiircr in the auricle and fireat 
v«-iii» < S 1-11 ), a tnitiimuni ninnonictcr placi-i) in lh« right nuHcle sli(>w» fre- 
quently oil prtwiirc at nil ilhnt ir, a prt^mrcciinal it> ihal orih«attn(»pher«l 
KD<I unmet inic» a drdih<tly nc^tivc nrcmiire. .Sdoinj; that the blood under 
thp>c nrcunMlanfra i» being driven along the great vvina by a )>ref«ir« which 
though low is alnayx abovo that of th« atmotphere, w« may uuuclude ihal 
the negative previirf produced in die vcntriclo ix the cause of this IdweriuK 
of the prewurc in the auricle, ihotigli it it unable to make itself felt ahiii); 
the greitt veins. 

§ 136. Th« •liiration of Ihf trrernl phntfr. We may, lirat of all, dbtin)fuUh 
certain main pliaiteH: [\ ) Tbesyatoleof theauriuW VSj The systole, proper, 
of llie vfBtrieleB, during which their fibres are in a state nf contraction, Itut' 
inn to '/ in FlgB. 75, Ttt. 77. (:1) Tbe dijiHtole of Ihe vent rides— that u to 
Bay. ilie time intenp-eDing between ibeir llbres eeaaiufi to contract and cnw 
Diencing to contract again. To tliew we may i>erha[s add t4) The iiaui(c »r 
rcsil iif the whole heart, comprising the [leriml Irom the ejidollhc rvlaxatioa 
of the veiilriclw to the Id^inning of lUe systole of the auricles ; iluring thia 
lime the wnll# are undergwtig no active change*. Dcitbi-r rt>ntrnctiug nor 
relnxing. their cavities Iwiug simply piusively filM by the inllux of blood. 

The mere inspection of nrnuwl nay wrie? of cardiac curves, howeviT tnkea 
— Ihoae. for instance, which wc hnw just i)i*CUMcd — will show, apart from 
any accurate measurements, ihnt the svslole "f the ntiricles is always very 
brief, that llie systiile of ths vcntricUs is alwuys very prolongwl— always 
Qccupviui,' a conBidcrablc portion of the whi>!c cycle- -and that the diastole uf 
ll»e whole heart, reckoued from the end either of the systole or of Ihe relaxa- 
tion of the veiilricle, is very various, tx'ing in <]uickly beating bearta very 
ahurl and in slowly beating hearts decidedly lunger. 

When we desire to arrive at more complete mensuremenis, wc are obliged 
to make me ^>f calculations based on various data; and theee give only 
approximate results. Naturally, the most interest ia attached to the dura- 
tion of eveuta iu tbe human heart. 

T1i« datum which perha|M ha§ been most largely used is tbe interval 
between the beginning of the Hrst and the occuiTenee iif the second sound. 
Thitt may be iletermim-d nith approximate correctness, and ia found to vaiy 
from O-Sftl to 11.327 w^imd, occupying from At) to 4G per cent. i>f the nbule 
|ier[t>d, and tiring fairly ouiniant tor <li8erent rates of heiiri-beai. That i» to 
aay, in a rapiilly iH-nliug lii-url it ii the juuses wbicli are nhortencd, and not 
the duniliiin nf tliv aeliud hi-at*. 

Tbe Dbaerver, iMtenine to (he sounds of the heart, make* a •ii(uaJ at eJich eveiiL 
•<■ a rvcurdiii]( Mirlace, lue dtflrrencn in time litlwci-n tbe niaila being lOMunired 
kby BmnB iir the tihralions of u lutiitii;-t'ork recurded on the tame aarface. I)r 

imutice it is fuuod [Nmible to reduce tli« errorsof obaerratJoa within very smalt 




Xow. wKikiCTrr beihv exnd cmiMiiiun of ihv tir»t »i>i]n<I, ii in ani)oul>lcdly 

11 «illi ihi- Kvxtoli- of lh« vpiitm'U**, thi>ii<!li tii<s<ili!v llw iicluiil com- 

Dtni of iu Imiiiiilii^ aiiilihir nuir Ix* iili^lilly iH'tiimi ihc itctntil iicgin- 

Tiin^ nf ilir tiiiiKCiiliir cotiirmcltniia. i^imiliirly ihc nrciirrvncv of the tecciDd 

■juntl, whidi, iiit wr h»v<- -vu. U (H-rminly due in llir clinsiirc- nl' the ■enii- 

loDftr Tilim, hiu )>ct.'fi litkvii !•> tnttrk lln- cliwc nl' (he veiitriciilar »vst>ile. 

And iin tkU ■D|>|NN>i(iuD Ihv intonal hrtnci-R the hc^iiiniiiif; of tlie tint aud 

llw iicrum-iiri' of tl>e i^cniKl tumnd hns l)c<n M-iiHnictl lu inilioiitin); »|>pr<>xi- 

ouilrty lilt' iliinitiiiii uf thr v-cntri<:(il«r rvfIoIc — ■'. c, ihv pvritKl during wliicli 

ih* trnlririiliir fil>rii> arv coiiinictiiig. \Vt> liiivv, howover, orj^d abuvc ihat 

tli« vmlni-lri fttill rvniain coDirnctcol fur ii brief period n^er ibe valvn are 

tk»l: if tlii» viv«T 1m> cwrrccl, llicn tbp iwcond cuuiid dms not mnrk the end 

tf tkf fifiole, UMJ the duraiiiMi of tbe sjHtole is milwr longer that tbe time 

■imi above. 

ibf I lot ertiii nation of lb« tcnaralf diirnliou of eucb of the thrue jieriutU (d' 
tbt iFiilricuIar Bvatolt' — vii., the ]>t^iliii^ up ut' lb« prtsaure, the <lUcharge of 
tb( niiit«nl£. nnd tb«- reiiiainiiij- eniplieil but cuiuracled — is mibjec't tn no 
BuA unnrtainty ihiit ii ueeA not be ioBistcd ou iii-re; it may, buwcvcr, be 
ml tkat, ruuKbly ajieakiiiK. «^:>L-b phiue occupies probuhly iibout 0. 1 wound. 
In li«uri tumtini: 72 timcii a iniiiui^, uriiieh mar t>e tukeD as tbe normal 
nif, Mcb i.tiiin: ciirdiiii: cycle would la^l abiiut 6>^ d^Muiid. ami taking 0.'^ 
mod a* ibc duratioii of ibe venlrietilur ByHiokMbc deduct Juii of tbU wiuild 
Invr a^ wctiud for tbu whole diaalole of (hu vciiirii-le. iiicludiii); il.-i n^laxti- 
Unn. tlir Intlrr orcupyiiiK ubotit or sumowhiil Wji iliaii 0.1 iu.t?i>iid. In thu 
liatr part of tbiii period iht'ru occunt Ibe M'stole of tlir aiiricln, tlii; cxucl 
duruii'i of wbicb it a ditlii-iilt to dcterniiiip, it being ban] t» aity wlu-n it 
mlly U>'ina. btil vrlii«b, if tbv cviitrnction of the grau v«iiis b« iucludul, 
luy [Thara be taken ns la«titt);. "U no Mvemue, 0.1 wond. The " |iuB«ire 
bimal,*' iberefore, during which nHther iiiiric^ nor ventricle are undci^iiiig 
BMfaUiufM, lasts about 0.4 hocoikI, and tbe alji»olut« paiii»e or rest during 
viich iMritber auricle nor ventricle are contracting or relaxing, about 0.3 
■cowl: if. however, a longer period be allotted to the ventricular eyslole, 
lUw perioiU muat be proportionately Hhurleiied. Tlie iVBtote of tbe ventricle 
Mloiraao iinmediaiely upon that of ibv auricles, that practically uo interral 
aiirt» between the two evenli. 

The duration of tbe iteveral phases may. for convenience luike, be arranged 
is s lalnilar form m folloun; but in reading the table the foregoing; remarks 
■t la tbe appruKiRiale or even uDcerlaiii character of some of the dalA must 
W Imnw In raim). 

^tfole of vetitr(c)« belore the opening nf die Minilunnr 
Talvei, while picMure ia atill getting up {probnltly ralhrr 

iMthaa) Il.l 

beaiNr of blood into aorta (about) 0,1 

Cb«tinu«d ooairactlon of tbe emptied Tentriele Ipoaslbljr 

rather mure tliant 0,1 

Total *y«l«la of the ventrit'le (probably tailivr nxxg 

IHaabile uf both aarii'le Rn<l vMilricte. neillM'r oontracting, 
••r '* paaaive Inlvrvul " (pn>l>ahlv rather leas than) . . 0.4 I 

Ryatole nf auricle ^abtxit or leM tlmn) IM j 

lKa*(i>l« or vciilricle. iiiclu'linj: rrt>xiiti"n and filliiiir. up to 
lb« txf inning uf the vcnuiuulur ivsiolr ((irotiably tiiilicr 
Ina Ihao) 



Total cardiac cycle 





! 137- We mny iww bricfl)r nninintiilitU' l]w main fitcte coiinecloc) willi tlx 
posnge of bliHMl through the liritrt. Thi- right auricle ilitring il> din»litl«, 
by the rclitxnlinD of iu imisculur dhm, nntl bv lli« liict (hat nil bnckwnni 
preAuro frum rbc vriitrii-Ie is rcinovixl by the closiug ofUM) tricuspid vnlrea, 
uHon but Unit; ri-siftdticc to (he ingrivs »t' blood from the veins. On lbs 
other bncid, the lilood in the tninks of buth the BU[>crior miil liirorior vena 
cava i» under n prcMUre, which, though diminishing b>«-ard the heart, re- 
luains higher thuti the pretaure obtaining iii the ititerior of the auricle ; (be 
blood in cotiwjijciice dows into the empty auricle, its prourcse in the case of 
lh« superior vodb mva bcinj* atdisted by gravity. At each inspiration thb 
tiow (as wcchall aee in ^pealciitg of respiration ) is favored by the dimiiuitioD 
of prcflBurc ill the heart aud great ves««ls caused bv the reepiralory loove- 
nients. Before this How liau gone on very lon^. the diastole of the ventricle 
be};iii6, 'H» cavity dilates, the IhipA of the tricuspid valve fall back, and blood 
for fiouie little tirne tloiva In itu unbroken stieaiu from the vena- m\x into 
ibe ventricle. In n »liori limii. howevtr. probubiy before very much i>luud 
h»H hud time M enter the- vcntrii'k-, the auricie id full ; and furthnith ita 
Hharp sudden sysiok- tnko place. Partly by rea^in of the buckwan) pr«B- 
jiuru ill the veiun. which incnruofs rupidly from the heart towmni the cupib 
Inricn, and which, at foinir diataiici- IVoiii thi- heart, in OMinted by tin- proenoo 
of vulvi-s ill ihr vtnoNit triinkf, but Mill miin> from thi.- fact that the xvrioU; 
begins at ihi? grrat veiuN thrmM-Ives and spreads thence over the auricle, the 
Ibfxw of llie auricular oonlnielimi i> £|>ent in driving the bigod, not liack 
into the reins, but into the ventricle, where ihe pri-wum in utill excceflingly 
Ii>w. Whether there u any backward How at all iritu the great vcIr«. or 
vhethor by the progressive character of the systole the flow of blood oon- 
tiuuee, io to speak, to follow up the systole without break, so tbnl the Mreain 
Irani the veins into the auricle is really cuutiniioue, is at present doubtful; 
though a slight positive wave of pressure synchronous with the auricular 
ayaUile, travelling backward along the great vcina, baa been observed, at least 
in OUHB where the heart la beating vigorously. 

The ventricle thus being tilled by the auricular svaiote, the play of th« 
tricuspid valves described above cornea iniu action, tlie auricular iysiole is 
iblluwed by that of the ventricle, and the jire^urc within the vetitricle, cut 
<dr frQm the auricle by tht- iricii^pid valves, in brou^-ht to bear ou the pul* 
monary leinibiDar valven and the I'libimu of blood on the other aide of tritno 
vatrea. Aa noon aa by the rapidly inereti^dn^ shortening of the ventricular 
fibnn the prc^aure nitliin the ventricle beouiuea greater than that tu the pub 
uionnry artery, the iiemilunar valven open and the alill continuing nyatolv 
duobareCH the contonts of the ventricle into that ve^isul. 

As the ventricle thui> ra|>idly and lorcihlv einptien itni-lf. either the trnnjucut 
Dcgative prauurc which innkra it« aj>pearance in the rear of the i-jected colunia 
4>f blood, or the eln»tic action of the aortic wall*. IcuJh tu a rellux of blood 
lowanl the ventricle, the eft'ect of which, however, is to close l)ie iwniiluiiar 
volvw* and tlni# to i>hut off thu blood in the dwteiided arlericri from tlio 
emptiefl vQiilricle. Kither iinme<lialely at or more probably fi}mv little time 
■Aer this dooingof the valves the venirieulnr Kv»iole emlif and relaxation 
bt^iDs; then once aum the cavity of the ventnclo bueomtw unfohlcd and 
finally divtciKlcl by the influx of blo<Kl, a negative prexiure devolopc^l bv 
the relaxation probably niiliiig ihc How from the auricle nnd greal wins. 

Utiring the whole of this time ^e left eid« bag with still grotMr eaotgy 
been eJteoutiug the same inanceuTn^ AtlhesaniQ time thai tha von» cavn 


•n Uioy (be riKht iiuricle, the pultnoniu-jr veim are fillioi; llie left ■iiriclv. 
Al l^mne time thai die risKt auricle ia cMntrai-tin];, itie left auricle it coR- 
ITUtiDi; Uw. The BTBtole of tlie left v^eotncle \a syDcbrnnous witli thrtt uf 
Uttcunt \-rtiLri(;le, Imt executed wiili frailer foree; siul tlte flow of blood 
a gnnn) •■n ilie iHt liile by the iiiitrul aod aortk valree in th« aamc war 
ilni it is on tlic right by tbe lricuj»j>iil valves ani) the viUves of the pul- 
murT arwy- 

"Hftati in a givcu |)erio(), but pi-rluiDS the must importaut factor of nil in 
ih dtUnuinatiiiQ of the nork of llie vasciilur niecliuDisni, the <|Uttntity 
qstted from the renlricle iulo the noria at i?acli systole, cannot as vet be said 

The Wort Oow. 

)18& W« can muiMire with apiirosioinlivc exactness the intrn-rcntrii'ular 
in. tbo U-iiglh of Mcb «yBlolc, and the number of tinKv the systole ia 

tobtTe Iieen aecuralely determined ; we are largely ublijjed to fall back oo 
nlealationa liavinf^ inanv sourcee of error. The jceueral result of soioe of 
ihaamlculaiioosgivca aFiout ItSO cramuia (<j oxa.) u the quantity of blood 
vlitb it driven from each ventricle at each eysu>le iu a fiill-j^rown man of 
I sice and weight, but Ibiii e«tiraale k probably tui> bi;;li. 

Im tb« dog tlifl iiuauiil^ liBB been vi|ietiiu»n tally <lei«nnined. by allowing (be 
fcauitoddlver iia eonteobi iliroujcb one branch or the aorta, all oibera being 
"p^T^ or blocked, into • reooiviT. (he contents of wliich are at iotervnl*. by an 
Upaloai coBlrivjini:*, rriiirni-rl in the right auricle. Tha time takon ta fill the 
nniw aitd tbc [luuilwr »f Wata eiccuted during ihiil time hviag aoted, the 
annn quantitT aitict«d at a beat la tbiuciveii. It ia found to vary very widely. 

VatttM Betbovi have been adopted lor cal(;ulatiag the average amonnt of 
Und ijected at each rantrictilar Hystolc. Tlie almpleAt method U to meaaare the 
oifadtj of the rfcmlly rpmavcd and m vet not rigid ventricle, flllod with blood 
•Mf 1 rirrware e>iua1 to tbo calculated nwnfe prea*uro in the veoitricle. On 
At ■ >ii that tbe whole cunienta of t£e T«alricle are iMMtcd at each 

■fi: -juld give the i]naallty driren Into tbe aorta ul each Htruke. The 

w«tbwl« arc ret; indirect. 

It ii CTHleat that exactly the came ijuantity must inue at a beat from each 
fntride: ibr if tbe right ventricle at eaih beat gave out rather leae than 
ll> kft, after a certain number of l>eatA tbe whole of the bkwd would be 
plLiiil in the svstemic circulation. Similarly, if tbe left ventricle gave 
Ml !■■ than tbe right, all the blood would soon be crowded into tbe lunjf*. 
1W tun that the pr«aaure in the right ventricle ia »o mucb leM tlian that in 
(he left (prabably 30 or 40 mm. aa comimrHl with 200 mm. of mercury), is 
Att. not Iu dlflbraioes in tlie tfuautilv of blixid in the cavities, but to the liitct 
tbal ibn ]>rri|>licnil redttance whidi baa to be overcome in the lungs b so 
smefa I^ than that in t^ iwM of the body. 

Il moat be mnemWred that though it ia »>' nilvaninjei^ to nwuik «f an 
tnrage rjnnntity tjerted at vach atnike, it ia more than pn>bablc that thai 
^•aaiiiy may vary witliin very wide llmila. Taking, hawcvvr, 180 grammes 
» Ibe r|u«ntity. in man, tjecteil at each stroke at a pnxauiv of 2-V> mm.' of 
OMTury, which ia oquivaieni to 3.21 melren of bloud, this meaiia that lite 
Ul Teatricle e capable at its systole of lifting 180 grammes 3.21 melna 
y^ i. a., it does 57H gramme-metres of work at each benU Supporing llx- 
Mft lo beat 72 timex a niinuta, this would give for tbe day's work of tbe 
Ul v«Btrid« nearly (JiMXX) kilogram in«>metrcs. Calculatingtlwworkof lbs 
fifU reotricle at one-fourlb iTiat of the left, the work of the whole h«an 

< A Wall caOmaM I* |art«Hlr UkcQ kuv^ 



would nmouiit lo 75,000 kiiograuime-melres, which ia jii«t ubotil the aniotint 
of work tlciiu ill (111' nHveiit ol' Sijowdon by a tolerubly heavy iubd. 

A cnlciiliitiun of more [intcliciil value- U the lollowiDg. Taking the 
riuatitity of bUiod n* i*i n( ihe hmly wei^ihl.. the bloud nf a man weighing 
76 kilus would Iw about A7G0 grniiiiiivM. If 180 ajaminea leA ibe veolricle 
•t each beat, a ciunntity C(|UivuIi:iit to the whole blood n-ould paoa ifarougb 
the heart in 3*2 beale, *.«., in k«t than half a minute. 

Tiis Pruiii. 

^ 138. We have seen that (he arteries, though always dislcnded. undergo 
at each systole of the ventricle a ti?mporar}' additional disteunoo. a Icmfuirarv 
additioual expansion s« that uheD the tinker is placed on an artery. *iich ua 
the radial, on inlerniillvnl |>reature on the linger, comio); and going with the 

Fro. IS. 

n«1t tmm MuioHirrn. 
in* flalloued Inlic 111 tlw f^irm Of • liaop t* ami)- ttinl u uiio md, vhflo Ihc al>»t tn» •nd U 
•KmIknI Ma law, Thu liiUilur of llm liilir. ttlM wltli iiilril. Ittuniufhl. hf lurvuof ■ inteooi)- 
ntnltic Mdluia oniboniitv Kiliilloii, liiro ninnrrili.n wtih nn aMcrT. In mui'h tbe Hmc hajmId llie 
(■■I tit Uio Dtimi; DiaiuuuelQi. Tht luvrcue vf [ircBurc lu tbe aner} Uilug tiuminliwil lo u« 
ImUowIiDop, UiuUluflnlKhUn tt, aDdc>'iTM[ianillDirly nKn«> tb« Bllwb*d t«itr. 

beat of the heart, h fell, and wbeu a lt):ht lever is ]>laci-d on tbc nrterr, Iho 
lever i* raited al «ach boat, falliuE hetwt^en. 

Thi* intermittent L-ximnsion which wc call the pulw, corrwprmding to the 
jerking outflow "f hlood tVinn a severed artery, is im-wnt in the artenc» only, 
DeiDiF, except under panit'ulnr circumNtnncca, aWnt from the vrius and 
cafiillBricM. The es]Hui»]on i* fn-iucnlh- vinhlc to tbc eye, unit in some 
cases, us where an artery has a hend, may cniifc n certain amount of loco* 
motion of the Tnsel, 



iitatyonrj iucivntt of preoHire wliicb is tlte cauM of the temporary 
01 oxiMiiMOD makes ilself fell, as we faavo seen, in the ourra of 


IiusRiH (M > BrnvnuoaiiArii iDiiiA>AN*n. 
II1|H<IIIH |auM uc oflilncd n that Uie ■aUlptjliiE tctrnmiaj'bedliptoTod. d tin nuall 

»(if UMknrtalimiiiMtMdpabitil. Tlw* an rominunlaiWd w uid nu«- 
I If tt* ln«t « wlilcli iBona roaiid ib> Bzwl fdnt /, Tbe live 'nd or (hit lenr BoiiUi b tight 
■MMr <rUtk iwHoaftMnpottanlud Tt« |iai«r Si plKvd bvocaUt two mull 
•( IMM <■ ■ ioSm abMi «■ t« rotolod bj ausoi of rtock-xirk ociaUJn*d la Uw bpt k. 
1kt|i9«rltihai«a«i(1totniTeUt>anllbrmm*. nttrnw gnAuiua lnoiuioa(TTaT)talmiBlM 
• ta* M Ih* ifAliB * tV niMiia of a MBm. and t>)r iMt Ihd pnmuf pul oq Um iirUfy (nn b* Ntfu- 
■■a tkt ItfW* OMpaltr Ik* |uIm mtanaaviM llttjr ItmM. 

MnU pWBW lalcciii bv ihr mrrcnry mnmimclcr ; but the ini-rtJa of the 
[jmrcoto th« epCL-ial vhiu-uctcn of ctu:h incrt^uec bot'oming visible. 

HiBit'i t!riiTn»mR>rli. 

VXb*kOTiitaw<ii|irr'n'V*i>iii*<>M'i>'<i i»tbo«m. lt,if(tiia>klcfefaiiiipiNi tadlaluMtrt 
te adfutl^ niarkla« tiii-i I. : II, rlnrkiAck ; l\ iMtfenl ymtm vpM ■faloh tradaK tt 
,MMn«HllH ft ttui 1 1 iif I ml ■ftii r>l>lilt 1 



In Fick'« fprine Diiini>iiiel<T (Fig. 78), in whii-Ii titc invrcMo of prcMUtv 
unfolil* a cunofl iipriuK iiml mi movt» n hver, the inrTtia » much Ivm, uul 
MtiafiuiUinr tmcingit may be Uikcn l>r \hif iiiiitriimettt. Oilier inetrumoaU 
bsve aIko men cl«vU«(l tor roounJing ihc spocinl characters of each incr, 

» AfkcJ-ii 

I-i'i*> "nuoKii nnoi TiiE Raciji. aitkut ur sum. 
Tba Tvnioil curTEd lluo, L.glTw tba na«]i>EHtiIviiilior««riltiit; luira iii«l«iib*n Uia Hm^ 
•nol psiwr KU mntloiila*. Th* <iitm4 InUmpLcil Uno ihuw Itnr ittirlanM (tam tne iwottia In 
aiDO «< th* chlcl plum at the pulw-WAni, tIk. ;g — commenMmont uid A eiul ut vrawton of 
wiair. p. piCKlicnllc uoteta. d. dlcfoUc noteb. C, ifleniilc cmi n, INMt^kKitlo nM. /. Um 
iM^rMlc nolcb. ThtM BM «l|ll*liied tn Iha Wxt lal« ■>□. 

of pnaeure or of \h\: cxiiimeion of the iirterv which ii> the result of lliat 
tneMaaei The eiui«8t sod nioet comnmn method of regiaterioK the ex[>aiuion 
of aa art«rj is that of simpi)' bringing a light lever to b«ar on the iiut«i()« 
of 111* artery. 



BI>B rubber puiDp, .. .' :i . i: . >iiuciiini-nl. to |irtircnl* nsanrl<A"l <.-iim.iit: t,f,f. uv Icrrn 
nMosiiii kciiui tuba, *t liiiermb «1 3) cm. ufiubliis: C.drom upon iitJeb uuliif Ii maA»-. II, 
fliockiwivk 111 rvroUc itrum.) 

A lever s^ially ailaplcd to reconi a pitlw traciiiz u called a sphygnio- 
granli, the iostniRMUit gcoenlly comprising a itniiill Iruvolling tvcordioR 
Mrtace ou which tha Uver wrHea. Thorv are many diflvrvnl fbmia of sphy^ 



tMpipb, bui llie g<>tienil nlnn of nnictun^ in th« samr. Fig. 79 ri>pr«KDtfi 
ID « duf runnwtic form the cakuUhI P^* of (he »phygnio^«pb, ItDown ss 
pii4geaa'« Tum] Fig. S2, Marvy'ii, which is id moro corhdod use]. The 
iainumt is gMOrally n[i{>lt(il to tho nxlinl iirtrrv bccniiee the ana offonJa 
• (■inn[«imp))OTt {*> Ibc Aili'mtii <>f tbo k-Vf-r, nnd because the position of 

pm. t& 


ftiM ravm na^BM> st a Hun or ^JiiT'inoaurnic Lxnw-plkndMtnicrTalaol Vem 
^■M*Mtarakiii(*ncOjallClubelnIoiihlchfliUi)Ufan<dbTthoMdd«nMRitwc>(«puia|>. Tbe 
^■»*«>* It mMlllliK nuu krA to itclu. u InJIoUrt bf lh« umn a*«r Uip pninaor (a* Bml neond- 
iQA<lf«lv««i«L TlMiMM v«mc>lllnndnwiift<an thaMinimltorilioieT«nl|iiliiiu7'«m<r« 
■*<telMlB|Ajik DOnv litlDvr, ouh tmoiplQla TtbfMloa of wUcti aceui«i> 1 JO aeiaBd. ftUowUi* 
^tab*Baa*nn<Hblchl«ul«upbjtb*miT«lnpMl4>lans3a(Tni.orib*tublBc Tbo««T« 
^■n>MW«<tftoMf>nntbark«dilMkl*nit of Um mUm : tkli la tiullcaittl by Ue dtrMiloii of 
^ ■*•» II win be obKtTDd iliai In ll» wan dtauui tera VL Itic nOeelod wan. tiNT&w tol • 
■^MAaumlo tivpel, bfoOBiM nawl Willi lh> |iriinu7 Hun. iKnni MaKST.) 

tk ulfrr, n«Hr to tbe lurfncc aii<t with tbe Aipimrt of the radtus b«lo«r ao 
ilat Mlc^iute prewure can be brought to bt-nr by the lover od the artery, » 
fcrcnble for niakine obwrvatiomt. It vuu, of cuurao, be applictl to other 
amritm. When ap[iiit)il to cIm radial ortvrr lomo such tntcing a» that 
4mM in Fig. 81 in obliiiiiccl. At acb bcvl bi-itt Iho lever rises rapidly and 
Ami hiU mote gnulually in n Hdc vrbich U more nr le» uneven. 



S 140. Wc have now to study the nnUirc ivDd characUrs of ihi' pul«« in 
greater detail. 

W« rnny fnr at once, und indeed have alreadv incidentally eccn, that llie 
pulse is eBSpniinlly due to the Hction of ptiyeical cuiieeB; it is the phyHcal 
result of the sudden injection of the conleote uf the ventricle intn the elxatic 
tubes called arteries; its more imporiani features may be explained on 
physical principles and may be illustrated by m«atiB of an artificial model 
[Fijr. 82], 

If two levers be placed on the arterial tubes of an artl6cial model Fig. 
61 &a., iS".(r., one near to the pump, and the other near to the peripheral 
reiUtance, with a conuderable length of tubing Ixiween them, and both 
leireni be made to write oa a reo<brdiug surface, one iniDiMliiitelv below the 
orhvr, mi that their curves can he more easily oomporeil, the fullowiug facts 
muv be ob.ierved, when the pump in Met to work regularly. They an- i>vrhn[M 
still better neeii if a numher of levers be similarly arrangeo nt ilitlcnmt 
di.ilunc^ from the pump ha in Fig. 8.1. 

At eiieh »t.rolc<! »!' the pump, Midi lever rises until it rctncbn< a maximum 
(Pig. 8.S, la, '2ti. i.-[c.") and ihi'u fall* again, thus d(«cribing a curve- The file 
is due Ui ihe i'xpiitiiii<)ii iif tin- part nf the lulio under tho lever, and tho fall 
IM due to that part i>f the lulw> n-liiriirng after the expansion to its prc\Hou» 
calibre. The curve in, thi'refi>re, the eurve of the expausioD (and relorn) of 
th« tube at the point an which the lever rests. We may call it the pulse- 
curve. It is obvious Ihttt the expansion |ins«c« by the lever in the form of a 
wave. At one moment tho lever is at mt ; the tube beneath it is simply 
distended to the normal amount indicative of the mean prasurc which at 
the tjme obtaius in the arterial tubes of the model; at tlie next moment the 
pulse expansion reachw the lever, and the lever begins to rise ; it continues 
to rise until the top uf the wave reaches it, after which it falU again undl 
finally it comes to rest, the wave having completely pacsed by. 

1^. KL 


A sovon DiKTRxwHUic i(KrKi»xv(iiTi'H< riF t fruc-wAV* N«q]ra ovu m Aktuit. 

It may perhaps be as well at once to warn the reader ihut the figure which 
we call the pulse-curre is not a leprcnonl^ttion af the pulw-wai-e ilMlf; it n 
^mply a repieMniation of the movenient», up and down, of the piece of ihp 
wair of the tubing at the spot on whieh the lever nste ijun'n^ M4 linu that 
the wave is passing over that spot. We may roughly repreM.'nt the wave in 

ihiiiHiiiii Pie< M in vrbicb tho wnvu «boira l>r tho i)i>tt«d liito i* pM«ing 
«MlM lab* («D(Mni in it mudilion of ruet hv the tliivk double lint') in Iho 
JiNdloB fromHbi C It must, however, (>e remeitiberecl tbnt tho irnvo 
itaiSpind is a mueh aborur ware ihao is the pulse-ware in reality (that 
Uk m w* BbBlI aae. about (1 nwtrw loi^), i. «., oocupia a smaller length 
WtM arterial airM«ni from thv heart /f toward the capillariw C 

Tbe curre* below A*. 1'. Z repreaont, in a similarly <tia{;raiDm8tic fluhioB, 
iktcorret deacribed, durio)* the passage of lli« wave, by leran plocttl on 
ibt points 1', y. t. At X the j-roiilcr part of the vrave has already p Moe d 
atoUie lerer, whi«fa durinff its passage haa already described tbe greater 
)Mt of its curve. sIiovd by ibe thick line, and has only now to describe the 
Mall fan. Hbown by the <loiied line. eornM[M)i)diug to the remainder of the 
an* m>m Jf lu //. At I'lhe lev«r i^ at the xuiniuit of tbe ware. At JT 
ds lerer baa only described u Hniall pun of the tieKinning of tbe wave, vis., 
bm C to X. tbe rest of the curve, us sliown by the dotted line, liarin? yet to 

Bvi to retora to tbe OMisideraticm of Via. 8^. 

t liL The rise of each lever i* soiitcwliat sudden, but the fall is more 
psdual, and is generally murkei! with Home irrcfrularititra whic^h we shall 
niv pnacDily. The Hmc u *tiil<U-ti bcn'Aiii'C tho sharp iitrDlce of the pump 
— Uwily drives a (jnantity uf tliiiil into the tubing and «•> »ttd>l(tiilv expands 
itilabe; tlte fall u more t;nidiinl because the elastic rutt-tion of the walla 
rfiha tab*, wbic-b htin-j* nbont the return of the tube to its foroMir calibre 
lAirlW expanding jxtwcr of the pump has ceased, is more gradual in its 

Tbaa Aaturai, the Rud<lenn<M nf the rise or up-etroke. and the more 
pailaal slope of the fall or dnwn-Hlroke, arw seen ako in natural pulse-curves 
Iskearrooi living arteries (Figs.81, 85. etc. 1. 
Uied, lira didereuee between the uf>-«lri>ke 
nri ibe down-strvike is even more marked 
ia ibr latter than in the former, the (k-livery 
(/ blood iVom the veotride being more rapid 
Ikia tbe iMue of water from a pump an onli- 
Birilr worked. 

It may here be noted tliai ibe imtual lixe 
<f fb« curve, that k the amount uf exciiniion 
<f ibi lover, ilcpeuibi in part (an does aluo to 
Sgrat axtent Ui« form of tlte curve) on the 
la awi l of prcMure cxcrtiNl by the lever on 
Ik labe. ir ibe lover only juHt tonrhcs the 
tub* ID lu upaoded aute, the rim will be 
NigBMauit. If. iMi tho other hand, the 
bnr ba praned down two firmly, the tube 
haath will not bt^ able to cx'paDd as it. 
Hlaiise wovld. and the rite of the lever 
■fli be proportionately diniiiiUhed. There 
btcertun prasure which must be exerted 
hr tbe lerer on tbe tube, tbe exact amount 
■bjRsdtng on tbe expansive power of the 
taUifand on the pressure exerted by tlie fluid in the tube, in order that tbe 
■ndig nay be best marked. This is shown in Fig. M5 in which are given 
thne trwdngs taken from the same radial artery witli the Kauie inatruraeat; 
in Iba lower curve the prewtire of tlie lever is too great, in the upper enrve 
H» mall, to bring out the i-haniut«ni seen meat distinctly in tJie middle 
<WTt with a medium presaure. 

PM. Ul 


Pci«i TsiaiAH i-Bos inn >4>U R^ 
lUAt, AsTUr rxpKi IHrnman 


iTbB Icltenmni sxiiUnsd In ■ IsMr 
■■ft of Uio (Ml.) 



Fia ««. 

Fro. M. 

li 142. It will be obttrred tliat ia Tig. 83, eurre I., wliteb is nearer 
|iiim{t. tiaes biglier, and rises more rupinly than curve II., wbiob ia fiit 
away from Ibe )Hmi{> ; tbal h t(> sny, al the lever Airther awnr froiD ifi? 
pump, tlie expautiioii U Uta hdiI take* place miire tloirljr ibmn at tbo lever 
Dearer the pump. Simil»r]}- in curve IV. tbe rise is sUll IcM, itnd takes 
place still lew rapidly limn in 11., and tbc wmc cbange is teen Ktill miir« 
marked in V. a* conipnn'd «ilti IV. ]ii fuel, if a number of Irvi-rw «i-re 
plae«d at ciuul diKtaiii-es nioiig tli<- arterial tubing of tbc model and the 
model were vrorklni^ profNTlv. with iiu iiili'ijiiiilp jHTiphcnil n.wlam'o, w« 
mi^bt irar'f out step hy step bow the rxpimiiioii, m* it tnivi-lleil nhmg the 
tube, gnt IcH niid Ici>e in amounl and itl lh<? «enie tira*^ Ivcciime more gradual 
in Its development, Ihc curve becoming lower and more flattened out, until 
in Uic nciglitiorhood of the artificial capillaries there wni> bnrdly iinr trac«S 
of it left. In other words, we might trace out step by et«p tbe graJua] dia- 
apmaranco of the pulse. 

The same changes, the aame gradual lowering and Hattening of the curv* 
may be seen iu natunil piil^e'trnciDgs, na for insunce in Pig. im, which it a 

a tracing from the dorsalia pedi* arlenr, 
ooiupared with the tracing from the radial 
artery. Fig. 85. taken from the ean>e indi- 
viduiil with the same tnalmnieut on the 
same ocenuon. litis feature in, of course, 
not ubvious in all puls^ourves taken from 
diflerenl iudividuals with diHerent iti^lni- 
ments and under varied circumtitauc-es; 
but if a series of curves from diderent 
Brtcric* were carefully tukt« under tlie same conditions it nouhl Iw found 
that the notlic tracing In higli*^r and more sudden thiin the carotid tracing, 
which, agnin, is higher and more sudden than ilic mdial tracing— the tibial 
trat^'ing being in turn »till lower and more flnttcne<l. The pulse-cnrvc diw 
ont hy becoming lower and lower and man? and more flntlenod out. 

And a little consideration will show us that this niual bo so. Tbe systole 
of the ventricle driven a quantity of blood into the already full aorta. Tbe 
sudden injection of thi* ijunnliiy of blood cspauds the portion of tbe aorta 
next to me heart, the part immediately ailjaccnl to the semilunar valves 
beginning to expand lirst, and the expnneiou traTclling ihenoe on to tbe end 
of this portion. In ihetsme war the expansion travels on from this portion 
through all the sueoeeding portions of tbe arterial system. For the total 
expansion required to make room fi>r the new quantity of blood is not pro- 
viaed by that jiorlion atone of the aorta into which tbe blood is aelually 
received: it is supplied by the whole arterial system; the old ijunnlity of 
blood which is replaced by the new in this first |>ortion has to find mom for 
itself in tbe reet of tbe nrterinl B|Mice. As the expansion travels onward, 
however, the ijiergntc of pressure which each portion transmits in tbe suc> 
ceeding portion will be less than that which it received thtm the nrecediug 
porliou. For the whole increase of prt^uure due to llie systole of the ven- 
tricle baa to be distributed over the whule of the arterial system ; tlie general 
mean arterial preMura ia. as we have seeu, maintained by repeated sysiolof. 
and any one systole baa to make il^ euutriliutifin to that mean prcMore : (lie 
increase of pressure which starts l>om the ventricle nmst, therefore. Icavc 
behind at each stage of its progrcM a fraction of itself; that is to Htr. the 
expansion is continually growing lew, as the pul.w travels from tbc neart 
to Uk capillaries. Moreovtir, wbde the expunnioi] of tbe norta next to the 
BmK is. so to speak, the direct etfectof thvM-ntolcof the ventricle, the expan- 
sion of tlw more diilaul artery i* thu cDivt of the systole transmitted by tbe 

' the elastic reaclion of the arterial trncl betwMU Ihe bmrt am) the 
auawnery: utd uaet this eladk mftimi in «Iuwer in i)i-\-eloiin)eiit tlian 
lb* kUmI antole, ibe ezpanaion of tlie mmv dixtant bhit}' in tluwrr lliau 
tkM «f 1^ lorta, iIm up^vlroke of the ptibe-curvc i» In* MiddcD, udJ the 
«W« palK-«urT« is niure Hatti-iiisi. 

n* object of tbe mtiilc b tn mpplr a fiinlribiili'>n to lliv mcBa prcaHir*, 
uJlb* pubebui cwcillntioci aborc aiiil hi-lon thiit ineiiii prcfRun — im OMil- 
lUiMwIiicIa (liininulm from tlic hnrt onminis hiding diimprd by the elARtlc 
mill «f til* artrriiv, ■nd po, Uttlv l>y little, colt Tcrtcd itita mvaa pmaure 
nXil ia tli« cKpillnms llic ibmu prasRura alone ramniiM — the oenllatioiw 
ianne A'amppt^mi. 

(143. If tn tikc mo<lel the {Hiints of ibo two lerere at dilli-nMil di»tniir«» 
ftm ibr pump bv niaced cxiittly one under the other ud the rceordJng eiir- 
fctt,il i« obviuuB tnat, the levcre being alike cxeept for their poeilion on th« 
laht.ur difitreiK'e id time between tlie movenienta of the two lerera will be 
^•n bv ui interval between the beginuin;^ of the curves they deiwribe, the 
KMding surface bHng made to travel suliicieiilly rapidly. 

If the novcmeuta of the lirn levers be thus compared, it will be tffio that 
6t far lever (Fijij. sy II. i oommenc-es later than the near one (Kii;. So I.) ; 
dc further a|)art ih« two levers are, the greater is the interval in time 
\tdina their curves. Compare the series I. to VI. (Fi{[. K3). This nieatift 
iiai ibt^ wave of espausioa, (he pulse-wave lakes some timt; to tmvcl along 
l&(Ub& In ilw same way it would be found that the rise of tlie near lever 
bnaaone ftaetion of a sccuml itHcr the .iirukc of the pump. 

The veloci^ with which the »u]Hi-wavf tnivcis depcuil* chiofly on the 
uwunt of risidily poaieMml l>y Itie tubing. Thv morv extensible (with cor- 
npOodlM Mutio reactinuj tlio lube, the slower i* the nave ; tho more ridd 
lkttnbebeeam«i>.tl)C ftster tbcwnve travels; in a perfectly rigid tul>r, whnl 
btWflaftic lube would Itc iIk pulse, beeomes a more Ehoek travelling with 
nrrgTMl rmpidity. The width of the tube is of much less influence, though 
■RMttng to MiDG observere the wave travels more ilowlv in the wider tuliw. 
The rate at which the normal (mke-wsve travels in tKe human body has 
kwn vaHoti'ly estimated at from 10 to 5 metrra per Mcond. In all proba- 
Ully the lower estimate is the more correct oue : bat it must be re«ieiiib«n(l 
thit (he nilo may vary verv cooaiderably under iliflerent condiliona. Aooord- 
ilgloall observers the velocity of the wave in pnariinii from the (jroin ta tlie 
bat is gTftater than in na^ioK from the axilla In the wrist 1 1! metres againat 
i mttnt). This U proiwbly due t.i tin- fact that the lonionil artery with ila 
taB eh w ia more ri};id than thu axillurA- and in bnmchi-^ So also in the 
I of ohildreu, ll>e wave traveU mor>e slowly than in the more ri^d 
I of the adall. 'I1i« velocity in al»o increiued by circuni;)tAiicea which 
baijrtta and decretued by thinv which Icmiii the mean nncrtal preaanre, 
met with incmsiiii; urcwun; the arturiiil witll.t become more, and with 
dldRiilliog pTBMure, Itm rifpd. Pnitiahly. aUn, the velocity t>f lh<- ]>tihie- 
•nv (lepeD<ls OQ ooiMlition»«f thearlfrinl wall*, which wecnnitot ndcciunttly 
^Mribt u mere difTert'im* in rigiililr. In exiierimt-nliug with artificial 
it ia found that different c|tuilit>cs of Indui-rubbar give rno to very 

mulu. ' 

I muM bo ulccn not to oonfmind the progms of ibe pnlte-wnve^i. e., 
rf tha fXpanioD of the art^rrial wal Is. with I he actual onward morenu-iit of 
lb btum) iunl^ The pitW-wave travels over llic moving blood somewhat as n 
npidly moving nattinil nave travels alone a iluggi»hly flowing river. ThiM 
iiila tfa« velocity of the pu)se>-wave is 6 or powibly even 10 metre* per 
1, that of tho current of the bhKid is not more than luilf a metrv per 
I vren iii (he lar^ arteries, and is still Ices in the smaller ooei. 



^ 144. Referring ojritin Im the ntulinn a'ivcn above luit to r«i;nn] lUo pulse- 
curve as a picture af the puliK-wavv, we miiv new sdi) that llio imlMr-wttve b 
«r very conaidentble U-tijcili. It' tv'i; know how luii)[ it iakir> lor the |>ulse- 
tritve tu ptaa ov«r iidv [H>iiil in thii nriorit^ luid huw fam il i« travel I i tig. w« 
can euMJIy calculate the k-nglli nf the wave:. In an (inliitarr jiuUe-curve the 
arlerj', uwiiig tn iho Hlnw return, i» nrrn nut to rc;(aia tliu valilirc which it luul 
before the nxrianbtion, until jii»t iu> ihc wxt vxpauvion t)e^iis — tliat i» to «j, 
the pubc-wavv tiikm the whole time of n uunlinc cycle, vii. : -fisiht seoond to 
paw l>y ihtj kvi-r. Taking the velocity "f llie inil»-wnvc a* 6 metere j>w 
■econd Uie le4>gth ofthc wave will be /slhs uf 6 moirea — or nearly A metraa. 
And even if we took a »iaaller estimate, by enppo«ine that t4)« real ftzpaa- 
flion nod return of the art«ry at any point Inok much lew time. t*y tV^i' 
Mcnnd, the length of the piil«e-wave would still be more than 'Z nieLn». But 
even in the tallest man the caitillarieH furthest from the beni't, thoKi in the 
ti|w of the toes, are not '2 melrefl distant from the heart. In other woril^ the 
Mlgtb of the pul»e-wavL- is much greater than the whole length of the arte- 
risTeyBtem, bo that the beginning of each wave has become lust in the Hmnll 
arteries and caiiiltariea some time before the end of it has finally passed away 
from the beginning of the anrliu 

We muBl now n^tuni to the conaiileration of certain special feaiiires in the 
pulse, which from the indication)! they give or auggeat of the eundilion of llie 
vascular system are ol\uu of eri^at iniereat. 

049. Ditrotism. In nearlr all pulite-tracinga, tbe curreof tlw expannoD 
anil recoil of the artery im broken by lito, tiiree, or several anialler eleraliona 
and deprea«ion»; «ecoiidurv wavin are imposed ujun the nindnmeuta) or 
primary wav& In the spWgmogruphic tracing fVntn the carotid, i-lg. 87, 

no. a. 

rvi««.TNACi)iw raoK C*aonii Aktieiit or IIultiiv Mas (ftom HonW. 
a, DDmnwoconiMI of upuulon oTBrtcrr. J, lununlt oftlieDninte. C, dlcnU; teconOur waT«, 
Aii^dluMlaMiMadaTT war*: p.Qouh prtetdlnf tliliL D.'upnodlimiMaailuy unTa. TtMimtva 
■bnali llMlof ■ nndnpDHt with un daulile TlbnUon* Id B Mooiiil, 

and in manv of ibo other tracings given, thcM cecimdary elevations ar« 
tuarke^l, as /{, f, />. When one such seoondarv elevation only is con^icu- 
ouR, so that the piiUe-eurve presents two notabto creets only, iha primary 
creit and a aeoondary one, the nuUe U said to be "dicrotic"; wnen two 
wcoodary creats are prominent, tne pu Ise is often called " tricrotic " ; where 
Mrcral, " polycrotic' As a general rule, the secondary el evatinns appear 
only on the deacending Hnib of the primary wave as in mml of the curves 
given, and the curve i* then spoken of aa " katacrotic." Sameliine», how- 
ever, the Srtl cl«vniion or cns<t i* not the highest but appear) on Ute aicend- 
tng portion of the main curve; Hiii'h a curve in apakeu of at "aDacrotio." 

or tbeae aeoondary elevations the moM freiuent, eonspicuoua, and impor- 



iMt b ih* one which uppeara w>iii« nj down on the dewmding ltntl>, nnd !• 
Mrbd C on Fix- ^~ itnd an mcMt uf the curvw hera given. It in nion: or 
luiJiitiiiiHr viiuble on all sphysmogmmf, and amy be mnmi in (Imjuv of the 
MTU ■* well ss of oUier itrtcrica. SomeliiDen it is m slight «< to be hnr<lly 
_i[liiilJhlr U other timos it muv be so marked «a to givp rim to a roally 
■Ut |iulM(Pig. 89), !.<;, ■ puW which oao )m fHt as dotible by the 





M- M-Aitnii>Tii^Vaii.H'Mii 41-11 Thvctiu ri-'U nil Mcwii!!!) AaltL lAniurtaa.) 
fta ■ -T*I> U*4liD or MlBKIl' tlll-IKITBN I-I It •IIIIIL Puw OT Man, «TfTlloi<l (ClVf,) 

hfif ; httMre it has been called the tliervtu^ ok'vutiiiii or the dicrotic ware, 

t Dotrh pr(>cr>]ing the clevntioii hv'we spoken of as the "dicrotic notch." 

Abfr it nor any other secondsry mvatioDi can lie raawnbed in the 

Mitft of blood- presBu re taken with a niaimmeter. Thi:* mnr l"> rxpliiitied, 

iVt have said $ 13!}, by the fact that the tnovcincnis of thu incrcunr 

Ama are too BlufEgisb to reproduce theee liner vanutione ; but dicmtiim t* 

in compicuoiM by its ahMOce in the tracin){« ^vcn by mora del iceloty 

'■^fpnttve iiMtmmeiila. Moreover, when the normal piilm? i» fcU by the 

V. Ridsl persons BikI theiuselvei imabk- !■> deloel any dicrollnm. But 

it (lo«« n-allv exirii iu the nunnikl pulse is ahonn by the ftu-t thai it 

toparp in a iaa*t unmbdukahlt^ manner in the tracing oblained bv allowing 

nt UojI to afMirt dtrm-tly fr»in an ojiL-ncd tmall artery, itucb as tKe dorsalia 

, friv, upon a rrconling lurlacc 

Um runstwit and consplcuouti than the dicrottP wrav4>, but vet apfteering 
'* I BMt •phvgR>ogr*inR, ix an devntiDn which appear* hi^lier up on this 
jBoiIine hmh of the main nave ; il in markeal R in Fig 87, and on several 
rda other ciini-a*. and i* frequently called the pre-dipro(ie wave ; it may 
tkuBW very nromiaent. Somctiinoa other atoondary wavr*. uneii called 
"fatdienitic. ' are »eeii following the dicrotic wave, a* iit D in Fig. ^7, and 
■■elher rurres; but thcM aronot ofttn pmH'nl, snd imuully, nven when 
pMnl, iDPomptFU04i». 

When tracing* are taken from mveral nrlcriea, or Irom tlie same artery 
tadir dtfltont coDititionn of the body, thcM aeoondnrT waves are found l» 
nij Terr oMHiderably, giving rite to many dwracteristic ibrma of pulse- 
eirrr. Were we able with certainty lo trace hnck the wveral featurcaof the 
111 their rmpective uiuses ; an adequate examination of sphygno* 
hie tracings would undoubtedly disclwe much valualde infornuitiflti 
cnuiig the contlitiou of the body presenling ihem. Unfortunately, the 
pnU«n of the origin of these teooDdiiry waves is a n>oet dilBcult and' oin- 
fbienv: so mueh ao, that the detailed interpretation of a sphygmograpbic 
Inaojt b still in n»<itit coses extremely uDoertain. 

\ m. The chief intenst attaches tu the nature and meaning of lite dicrotic 
•atn In general, the main cotidiiiuns favoring dicroiimu are (1) a highly 
■ niwilili and elastic anenal null, (2) s\ cuminiraiivcly lnw mean pressure, 
letfing the oxtensilde and eluAlic reactimi of the arterial wall fre^ M>opo to 
act aiM (3) ■ sufficiently vigorous and sufficiently rapid Uroke of the ren- 
Hiek. 'The developmait of the dicrotic wave niay prol*ably be explained as 



At eiicli heat the lime durbijc which Uic coiireuu of the left v«>Dlr 
iDJei'leil iulo tbe aurta is, ai ive have neeti (^ I3ii), verr hri«r. The ex]Mii- 
MOD of the aorla u very ■ik1iI«u, tunl thu oenMliou of tnat cxpannoa U aln 
very wuddeii. 

Now, wh«n fttiul Li b<,^iig driven with own > Rtciiilv prrK^iire through an 
^Ulie tube or it .■'viitcim iif diutic tiilMW, Icvora plucoii oil thi- lubo will 
detcribc ctirvc ludiniting vnriiitionsin Iho (linmc'Ierof tholtibo,)f iheinHow 
Into the tube be Hudiluiily slo[i|io<l, lu by Hhnrply turning a stop-cock ; and a 
cotnparisoR of IcveTS puiood at JiffOTeiil distancea from the stop-cock will 
show that thcxe vanatioas of dtamel«r travel donm tJic ttibo from the stop- 
cock ill the form of waves. The lever near t)i« stop-cock will first of all (all. 
but Bpeodilr begin to rise again, and this subsequenl rise will be followed by 
another thil, afler which there tnnj be one or more siiccceding rises and fnllft— • 
that is, oscilliitions — with decreasing amplitTido), until the fluid comes to rest. 
The levers further from the ston-cock will describe curves, similar to the 
above in ibrm but of lesa amplitude, aud it will be found that tbeee occur 
nmewhat later in time, the more ^ the furlher the lever is from tbe stop- 
cock. UbviouHly these waves are generated at or near tbe stop-tywk, am) 
tnvel thence along the tubing. 

We may infer that nt each licat of the heart aimilur warea would be 
frenerated at the rmit nf the uorta u[>on the xudilen enuuiliou of tlie How from 
tbe ventricle, and would travel theuee along the elantic arierie-. Tbe fai^ 
liiat each beat in rapidly nucci-eded hy another, ntiil that the How which *ud- 
denly ceases ia aliu, by the uutiire of the ventricular stroke, siiddvnly mt' 
ented, may render tlie wavia more complicaUid, hut will not changv loeir 
«wentinl nature. 

The exact intenirelatinn of the generation of th<'«o waves b [wrhaiM not 
without difficulty, but two factors seem of especial importance. In the firtt 
place, as we have already more than once srtid, when a rapid flow is suddenlr 
stopped a negative pressure makes its appearance behiud the column of fluia. 
In n rigid tube this simply lcn<ts to a reflux of Huid. In an elastic tube its 
elleci^ are complicated i>v the second factor, the elastic action aud inertia of 
the walls of the tube. Upon the sudden ceMuiliou of the tluw, the expanMoii 
of the tube, or as we may nt once say. of the aorta, ceases, the vensel beg;iiia 
to shrink, and the lever placed on it» waliii. tut from .1 onward in tite pube- 
curre. This abrinking i« in part due to the etastii- reaction of the walU of 
U)e aorta, but la inereaaed by the " suotion " action of (be nirgative preM^I 
apokea uf above. In thus shrinking, however, under theac cumbin*^ cwimH 
tne aorta, through the Inertia of iltt walU, nvenihoots the mark, it in carrietl 
beyond ita imtural calibre — i.e.. the diameter it wuuld ]>(MU»ti if leli to itcclf 
with (ho prcMure innide am) uulcide euual ; it i<hrink;i ttiu much, and ooitae- 
•e<)ueii(lr hcciiu ngnin Ut expand. This sucomlnry expansion (taking for 
simplicity sake a pulac-curve lu which the so called prc-dicrotic wave. B, is 
ftbaoat or inconspicuous) ciui<w« the necoiidarv riw of the lover up (o C— tbat 
IB, the dicrotic nse. In thus cxgnindriig again, tlie aorta lends to draw bock 
toward the heart the column of blood which by loss of momentum had come 
to rest, or, indc«d, under the intlucncB of the negative prcasuie s))okeD of 
above, was already undergoing a roHiix. In this secondary expansion, more- 
over, tlie aorta is oy tbe inertia of its walla, aided by that of the blood, again 
carried, so to speak, beyond its mark, so that no sooner has it become ex- 
panded and filled with iluid to a uertain extent than it again begins to shrink 
ae from Oooward. And thi» .shrinking may in a siintJiir luantier to the firvl 
be followed by a furllier expansion and sbriukiug. giving rise to a poctt- 
dicrotic wave, or it may be to poet-dicndic wavei. And the »ucoeMn\-o 
changes thus inauKurate<l at the root of (be aiirta travel na »> mniij 



riH|(tte utorUI ayatvin. iliminlshiiig H tbrr go. It irilt lie olwcrvvd Uinl 
brtSFJavclotmient uf the«- wave* n certain quality in lh« walk of Um tubing 
■ iwrrwary. Ttu> tnlw niiul ItPHichaspnanPwrawIiviint mtauop«n liiiDen; 
tkrvaUi niMt be '>f Huch a kind that tii« tube romniiw open wben emptv — 
i t, ■bea the atiiuwph«rlc prcautv i« equal inxiilo and outside — «K tlint w)i«o 
il thriBkl too mtlcli it expands eigain in stiiving li> rc-;!Ain its natural calibre. 
1k> *e bavt* Men to be a cbaracteristic oF the arteries. A (x>]Iapaib)e liitie 
•f lUl BWQibraiie will not »hi>w the pbetionicna; Hiich a tube n'beii ilii- iiu>j>- 
Mcfc ■> tarunl i-ollaieea and ciiipttea iifeif. conlinuiD^ to be collaftfieil witli- 
gd >iiT diort tu ex iMud aj{ain. 

Is llie above ex plaitaliun no nM-ntion baa been made of the cloaiue of tlie 
•MiluDar valvro ; we almll Imve lo >.\vak of these a little later on in refer- 
ni| lo the pr^v^licnitiv wave, ami biiall M'e tliui, nmler the view w<- have juat 
|i(*ii, tho clgting uf lite fieDiilitnar valves is to be regunli-d rather a» the 
tttCt tlMn iho cauw of ibc dii-mtie nave. Manjr auihom, however, givo no 
hRnntation of th« dicrnttc wave diflerent from tJiat deliiitol nbiive. Thus, 
kbliabl tlifll ibo primarv sbrinlciiig I'runi A onward, being brouglit to hear 
MlWcolamn of blood already come to nat, in face of the great prcwure id 
fiwl.driim the blmid Imck ngainst the *eniiliinar valrcw. iliiin cimiug them, 
ni that the imiMCt of tlie nilunin of IiIihhI ajruiiist ihn valves tttmrie a new 
nn of cxpanawD, which relnrorcintr ihn natural tiniduiicy of the ehutU- 
nib to exgiand again after thi-ir pritmirv nbriuktng, pniduen the dicrolie 
■m C On this vi*-w, it i» lli" blowl drivi-n baek from ihr valves which 
•ifMik the arti-ry ; on iIm- view given nlmvc, it is iho oxpaiiding artery which 
4i»s tlic hI'X"! twck tinrnrd ihr vnlnw, 

Uonover. quite other virn» hnvc been or arc held cuncorning this dicrotic 
nra Art^>^dinK to many nulh'irv, il is what i* ciillcil a " reflected " wave. 
Tbw.*)ien the lube of the artitieial luodcl bearing two levers is blocked just 
kinad ibeiar lerer, lbs primary wave beeen tobeaooompanied byasccoiMl 
aant which al the &r kver b seen doee to, and often fiiaed into, the primary 
ant (Fig. f*3, \'I. <■'), hut al the near lever is at some distance from it 
(Pi|.83,l. i'). lieiu^ the further from il the longer tlie interval b«tnt«n the 
mm aaij the bli>ck in the tuht?. The second wave is evidently the primary 
••*« rtAeded at the block and imvelling backward toward the pimip. ft 
tkm. of eouiae, (MWCa the far lever liefure the near one. And it has been 
m^Kii that the dicrotic wave nf the tmliw is really audi a reflected wave, 
Mulnl riilM-r St tlw iDiniite arierius and i-apillariea, or at the points of bifiir- 
Bttiwof the krger arterie*. and liavidling backward to the aoilA. Dot if 
lib mr^tba c»V. the ilistanci^ l>ctwe(-n the primary erMt and the dicnitic 
<pM oaglit to be Ion in arteriei more diitunt from Ihan in those nearer to 
ibtbmrt, JDSt M in tbo Hrliltcial •cbenie the ri-tlecteil wave is fused with a 
|*iury wave near the block (Fig. 83. VI. •> a. a'), but bcoomes more mid 
HR trparattd from it the l\irtlier back toward ihv. pump wa trace it i Fig. 
I3,L 1 ir. ')'). N»w. ihi^ is not the caae with the ilicrotic wave, i'areful 

iimneiiis show that the distance between the primary and dicrotic crtata 
■ ■tier grCBter. or certnioty not Ims, in the xmnllcr or more distant artvrice 
tbn in the larger or nearer ones. This feature indeed prnve« that the 
difMie wave cannot be due to reflection at the peripherr. or. indeed, in niiy 
nf ■ Teimcrade wave. Uendee, tbe multitudinous peripheral division woul^ 
ndtr ooe large periphically rejected wave impooible. Again, the more 
^iQy the primary wave is obliterated, or at least diminished, on its way to 
■b peripbery, the las conspieuoiis should be the dicrotic wave. (lenoe 
bunwed exictnubilily and increased elasUc reaction of the arterial walla 
■dick tend touaeup rapidly the priiuari,- wave.ahould also lessen thedtcruiie 

■ \>v;i.AR MECHAX19M. 

;■ 1 -..jt::- 7 : raa th«e conilitioiis, as we havD said, are favnr 

..::■-. : ;hr liiiTniii' wave. 

■< . rluit? sv,<i till' other conditions which favor dicrotUin 

i:» \;v.".,'. :."..#<,' whidi would favor such a developmeat of 

'.-.- 13 !.i» '.-t.>:: di'^'rilKil above, and their absence would be 

.I !.■ ■; -t^ka; '.I'sui'h wuves. ThiiH dicrotiaiii is Icaa marked 

v- -..' ' 1?:-''^' of old people) than in healthy elastic ones; 

. :., , wa-j ■> so naUilv nor shrinks so readily, and hence 

1,1.; ■ ,■ '. -■* '■? siu'h s*fondary waves. Again, dicrotism is 

. 1 ■■ I .. -['v.i', irtt'rial jiresiure is low than wheti it is high; 

, .. . ■ ,*. -1 - : uvd wheu absetit, or increased whoii sliebtly 

; -.■ , i; ' rf way or another, the mean prusnure. Row, 

v.. • ■> : ^'1. :'.••: iruries are kept continuallv much ex]Hinded. 

.• "< w .-n:M.'i; 'f further exiianeion ; that is to say, are, 

....1. ' :<iu'- !ii ::ll:^ii[i<.>naI expansion due to the systole is not 

. ,1 > t <•« ^-ll■:■.^^'v tor the arterial walls to swing backward 

•i. 1,,. tii.t nu^f a Itss tendency to the development of 

., -. ^^ U.I ii- mail pn'ssure is low, the oppusit« slate of 

- ..., . x,,i., 1 ■.■iir>f. chat the ventricular stroke is ade<juat«iy 

. ,»»..- hihl; in, n.'[ to diminisherl cardiac force, but to 

. , i-i:i;iiv . : !n' rvliitively empty but highly distCD!<ible 

> I ,.,..:i.i, i;ni, -iiiliti,: r.ipjdlv back, eiitci^ uj>on a secoDtl- 

1, ,. ... <...! -ivii .1 third. 

. .....< 'I 'ill <,.ii> be applied to uxpluiii why sometimes 

., ^,. ......^'.i 1 .1 :'arti<.'ular artery ubilG it remains little 

■. -!■ 111. [u t'xiierinieuting with an artiticial tubing; 

. . , ■■ ,.\'.. i'lsical I'hnrapters of which remain ihe 

■ ■. •.--tiA-.y .uid the secoiidury wiivw retain the same 

..ii;; :■■-■ tubing, .-avf i)nly that both gradually 

,..,..1. i> .11!. 1 ill the natural circulatiou, when the 

. . „ ' I I :.':iii ihroiigbuut, the jiulse curve, as a rule. 

.... ., ,i..-K-;irs througbijut, save that it is gradually 

,.-,-.■ »iiv to mtbsiiiute for the first section of the 

..,.-.,'■ ■-■.■ -.iliiui;; this at the stroke of the pump, on 

.,., i..„ ■! -Ii.'w neither primary nor secondary ex - 

. i:.., .■;..■ .'[' the pump's Stroke Would be transmitted 

;,,.i . Mvti.'ii. and liert the primury and ^coiidary 

• .'\ '.it'Lti. This is an extreme case, but the same 

,. . I 1 -.■. iii;ri.t' ill putwiiig from a more rigid, that is, 
, . . .11 .i.iir. !.. K le^s rigiil, more cxtc-nsibic and elastic 

i 1.. ^,.i;irv t<xpansions, in spite of the general dauip- 

,.,..% ;i, i.-iiac. Similarly in the living body a pulse- 

> .I'liu'Iling along arteries in which the mean 

' ...1..1 !■.■ ilivivlun.' practically somewhat rigid, is not 

. . '.,, [III.' wry markedly dicrotic when it conieij to a 

. .. ....] .1. 'iii'iiii pressure 1:; low (and we shall soe pres- 

, I.. 1 1 . iiiid the walls iif which arc therefore for 

. , > ,. ,.' .i'..>[vii-^il>lt.' than the rest. 
. . I. 'i i.-.i'1'viiiion made above (^ 141 ) that the curve 

■ K- :.'■ nniiilii'd by llic jtressure exerted by the 

. . , i;i,i ib:Lt hcni'i', ill the saniL> artery and with the 

. .. ii.ii.. and cvfti tilt; sjiecial features of the curve 

n. .i' |.ivs.*ure with which the lever is pressed 

V ;:._,^ \w amount of dierotism apparenl in a pulise 

...>..!!■ i\trted by the lever. In Fig. 6'>. for 





iiMlnnn!, th* dlentie wnvc 1* nxtre erident in tbo mUMl* tlian in tbe upper 

1 147. T\w pro-<llcrotic wnvi' (mnrkfr) !i on Fig. t^7, and on wveral otlier 
flf lhi> puU«^urva>, which prt-ccdi-* Ihc dicrotic wsva and is still nwre 
vvriililr thxn thai vfsvo, Ih-idi iu)mciimc» slight or even invisible and some- 
tiuMi onoRpiciiDUH, Una given rue Ui rauch conirovenir. Id th« iiitorpretati»n 
of UiN ilicnitiu ware givvu io Uto prccMliQg paragraph it was staled that the 
nrgntivn prrMur^ 'kvcluj>rd on the wsMtiun of the How in the rear of the 
cohmtti of hlix)d, led by itMlf (o a reflux toward the veniricle: nni) it ha* 
been suggeet^ that at this reHiix mcclinf; and cloeiuir the seniiluoaf ralvc* 
■tKfbt n RDiall wave of expansion b«t<>re the larger dicrotic ware bu hwi 
tinKf Io develop itself, On this view tbe nniiliitur vmlvea wouhl be actiinlly 
cIimmI l>ef<ife the oecurreflee of tbe Mcondary dicrotic expansion of the 
artehnl vinlls, thixiKb tbe larjcer, more powt^rfnl reflux of tliio laUr event 
iDiut rvtider tbe cliMure more complete, and in doing ta [ximitilv givra riee 
to tbd Moond sound. Accordini;. Iiowerer, to lite tecond viviv glvat in the 
Mne Mimgrapb, which reKanbi (be reflux due to the vjiriuliing of the 
mtlery in face uf (lie ^ratt prt-Mttrc in front art firmlir chMine Ibe soniilunar 
vmlvet, uxJ an ibtu startiii); tbe scctMidury dicmtic wavu ot cx|Mnsion, itie 
firm doaiDg of tbe temliuniu- valve* nust Uike place before the boginniug. 
iMt (Itirini the developmeul of the dicrotic wave ; il is mill pomJhlc. however, 
even on tnie view, m od the other, to iiU]>piN(C that an antix'cdeDt rvflux, due 
to the negative prenure wci-oeding the ucmatioii of flow from the ventricle, 
doMa lb« va]v4« and slarti tbe p^^di<'rl>tic wave. But the matter is one not 
ytl bcvrind the (tage of controvervy. 

g 14&. Ill ao anftrcrotte yulu- the lirat rise is not tbe highest, bnt a second 
rise t II. Kig. aH) which follows aiul in Mpnnitcl from it by a notch is hif[hcr 
Umn, or at lewt aa high, aa llaalf. Sucb an aiiarcrolio wave, tJiougfa it may 
MMiMtina be proiluoed tem|H>rHrily in healthy persons, is senerally ama- 
dhtted wltb disnued conditions, usually such in which (he arterieB are ab* 
noniially riKid. In dt-Hi-rihing tbe vctilricular aysiole, wc spoke of tbe 

iinwHirv within the vt-otriili' as reaching its maximum jnst before the open- 
Dg uf the seniihinar valvcn ; and ibis is apparently the uuruial event ; but 
then are <:urves which seem to show Ihai after Ibe linti sudden rim of 
prawuru wbi«b opeu» tbe valves, followed by a brief lenening of pniKuro, 
which appears on (be curve us a notch, the pr««ieure tuay again riae.and that 
to a |Kiint higher than before. AihI a similar curve is xoinetimed deecribed 
by tbd frunt-to-back diameter of tbe ventricle. The syslule o|ieiu tbe valve 
■• it wvtt with a burst ; thia is followed by a slight relajxto. and then the 
systiile, strvDgtbeuing again, dischargee tbe whole uftla' ventricular contents 
inlii tbe aurta and su bringti about a tardy maximum exiiiuiaton. And what 
is tbii* started in Ibe at*na travels onward over the arterial Mvstem. It is 
ditficnlt U> »ce bow tbeae anacrotic events can lie priHluceil, except by a 
certain irregularity in tl>e ventricular systole; aiHl, indi-cd, the iinacrotic 
pulac in rn-i|iii:ully awuciatitl with some disease or defect of tlu^ ventricle. 

( 14S. I'l Hom fiuhf. l-'nder ct-rtHin i'iri-umstance!< the puW may be car- 
rierl on frtmi th<i arleriiii thn^iKb iIk- CHpilliirii-x into the veins. Thus, as we 
•ball see Inter •>». whi-n iht- Hnliviiry ^^liuid ia aeltvcly K'crcting, the blood 
nmy iw>ir from the gland through iIh; vcini> in a rapid pulsating stream. 
T]>r nrrvoii* vvcnis wbieh give ru« to tbo secretion of stilivii, lead al [be 
tame time, by the agcnry of vasomotor ocrvce, of whieh we will presently 
•peak, to n dilatali'iii of the xmall arli-tii-a of the gland. When the gland is 
at rrst tile minute arteries arv, u wc sbnll kc, sonicw but constricted and uar- 
rnwnl, and thus contribute largely to the peHpberal resistance in ibe part ; 
tliia iwripberal recistaaco throws into actio«i the elastic projwrtkti of tbe 


email arteries leailing ti) the gland, and the remnant of the pulse reaching 
these arteries is, as we Ijefore explnined, tinally deatruved. When the minute 
arteries are dilated, their widened ehanuets allow the blood to flow more 
«aidi!.v ihrouj^h them and with less friction ; the peripheral resistance vhich 
they normally offer is thus lessened. In consequence of this the elasticitv of 
the walh of the small arteries is brought into play to a less extent duu 
before, nnd these small arteries cease to do their share in destroying the 
pulse which comes down to them from the larger arteries. As in the cue of 
the arliHeial model, where the " peripheral " tuning is kept open, not enough 
elasticity is brought into play to couvert the intermittent arterial flow into a 
continuous one, and the pulse which reaches the arteries of the gland paaKS 
on through them and through the capillaries, and is continued on into the 
veins. A similar venous pulse is also sometimes seen in other organs. 

fureful Inieings of the great veins in the neighborhood of the heart show 
elevations and depressions, which appear due to the variations of in tra-cardiac 
(nuriciiUr) pressure, and which may, perhaps, be spoken of aa constituting 
a " vcuoua pulse." though they have a quite difierent origin from the venous 
pulse just descrihetl iu the salivary gland ; but at present they need further 
elucidiition. In casea, however, of insufficiency of^ the tricuspid valves, the 
systole of the ventricle makes itself distinctly felt in the great veins ; and 1 
distention travelling backward from the heart becomes very visible in the 
veins of the neck. This is simiettmes spoken of as a venous pulse. 

Variations ()f pressure in the great veins, due to the respiratory move- 
ments, are also sometimes spoken of as a venous pulse; the nature of these 
variations will be exp1aiuc<l in treating of respiration. 

The Regulation and Auaitatios ok the Vawui-ah Mechamsh. 

Tile Jte/jiihitioii of the Beat of the Heart. 

§ 150, So far the facts with which we have had to deal, with the exception 
of the heart's heat itself, have been simply physical facts. All the essential 
phenomena which we have studied may be reproduced on a dead model. 
Buch an unvarying mechanical vascular system would, however, be uaeless to 
a living body whose actions were at all complicated. The prominent feature 
of a living mechanism is the [>ower of adapting itself to changes in its 
internal and external circumstances. In such a system as we have sketched 
above there would be but scanty |><>wer of adaptation. The well-constructed 
machine might work with beautiful regularity ; but its regularity would be 
its destruction. The same quantity of bloo<l would always flow in the same 
steadv stream through each and even' tissue and organ, irrespective of local 
an<l general wants. The brain ann the stomach, whether at work and 
needing much, or at re.-^t and needing little, would receive their ration of 
bloiwl, allotted with a pernicious monotony. Just the same amount of blood 
would pus.' througli the skin on the hotten as on the coldest day. The 
canon of the life of every part fur the whole period of its existence would 
be furnished by the iiihoni diameter of its bloodvessels, and by the unvarying 
motive power of the heart. 

Such a rigid system, however, does not exist in actual living beings. The 
vascular mechani.«m iu all animals in which it is present is capable of local 
and general modifications, adapting it to local and ceneral changes of cir- 
cumstance. Tliei* modilicalions fall into two great classes: 

1. Changes in the heart's beat. These, being central, have of course a 
general effect ; they influence or may influence the whole body. 



1. Oiaii|;» in llie peripbentl rewlimre, due to variations in tlie celihn- of 
iji« niioiite arteri«v, lirouybi about by tJie ageucjr of tbeir couirarlil« luiiv- 
itiUr coaU. TIkm cbangai mny be dtber local, aflbctine a uarlictilur 
vuctilar area only, ur genenJ, atfiKUiig all or nearlj all ihe Dloutlva»els of 
tbe body. 

Theae two da«e8 of «v«dI« are cbiefty governed by (be ncrrou* tvMeni. It 
)• by ineaiia of lli« ii«rvoU)i •rctcm thiit tl;u liciirt'* Ixtul imil the ciilihrA of 
tbo minute oriemti are bmiigbt into n-lntion wiili ciicli otber.eixl with almost 
vvorv [«n of the IkiiIv. It ii by int.<nns uf lliv nvrvous «yatviii scliog ciihrr 
Ob tM heart or ud tbe »inal) iirt«rM«. or on IkiiIi, tlint it change of drcnm- 
MaocM Bfieting citiwr the whole or a port of (hi- lioiiv is mvt by c^nijiciwitinj; 
or ngulativc cliaiigci> in ibe (low of blood. It i* by niiL-»nc of tbi- nervous 
tjfUim ibal an orgnn Ims a more full supply of blood when at work than 
when at net, that the lide of blood ihrcuch lli« «kin rises and ebbs nilh tbe 
rift and (all of the (eniperaluTe of the air. that the work of the heart la 
tctppered to meet the strain of overfull arleriee, aud that the arterial gates 
• ipTD and Hbut as ibe force of the central puni|i waxee and W8u«8. The 
study of these changes ljecoiiie«,tbei«fore,b> a iar^e extent a study of uervoua 
art inns. 

The drcutalioD mar abu Iw modifled by events not belunj^n^ to either of 
the above two classes. I1iu», in thin or ibat peripheral area, obaiigivi in iJie 
capillary walls and the waltn of the minute arteries and veins may lead to 
an increase of tlie tendencv of thL- blond cirouuclea to adhere to Ih*! vu.-H'nlar 
walls, and to, i|uile apart from any diauj/e in the calibre of tli<! blood v<rtte Ik, 
may lead to increase of ihi^ periplx^nil moxtttnce. Thin is wen in un vxtreme 
cKM ill in dam mat ion, Inti may [Hjwibly intervene to a Uw extent in the 
nnlinary mndilion of the circulation, unit niuy al»o be under the iuHuence 
I ihu nrrvouB system. Further, any deciilwi chunge in lb* quantity of 
actually in circulation must aUo inrtiience thir working of the vascular 
ninisni. But both lho« phnngcs arc iinim|H>nant compiirod with the 
two kiiulfi of chiin);t'8. Ilciice, the two nn»l ini{H>rlHnt problems for 
us tit Mudy nr^'. 1. how the nervous system regulates tlit^ bent of the heart, 
anil 'J, how lid' iicr\'uu!- system regulates the calibra of tbe bloodv^sels. We 
will finst cNiimitler the former problem. 

<i 16L It will be netmaary now lo take up certain points tyiiiceniing the 
minute Hnicture of tiM heart, which we had previously jxwtjMtned ; and 
iinre much of mit knowlcilgt^ nf liie nervuus mechanisti) of th« b<«t of the 
benrt i» drrivtsd from expcriincntH on tbe hearts of cold' blooded nriimiils, 
iiiof« particularly of the fru^. it will be dtwrablc to consider tbew as well as 
the tnatHtnalinn hi-«rl. 

t iir<lt<tr iiMi'fulnr tU'iir. The vcntrii-le i)f the frog'n heart is composwl of 
miiiolc i»j>iii<n<-KhB|>ctl tibn« or fihre-oell*. vuch i-oniAining a uiiclciis tn its 
middle, mid tapering i<> n pout itt each end ; Koim^timiit, honevcr, tbi.': end is 
forked or even branched. Th«Me filtr>^ «r tilinf-ocll*. in fact, resemble plain 
eular librt» save that ibey are somevrhal iarvvr and that their substance 

Wriatnl. The strialion is duo, like the striation of a Ktrialed muscle 
t. 111 alternate dim and bright tHtuds, hut is rarely so distinct as in a 
rial rtbre: it is ver}- apt to be obscured hy the prownce of dispersed 
ilinlinrt granules, which, in msny cases at all uvenle, are of a fatty nature. 
Like th*- ])lai» oiutculur fibre, tb« cardiac muscular tibre has no dtetinct 



A ntinilwr of tbew fi1ir«a are jniiied br oenwnt Bill»Uui«e infi tinuJI 
Uiuillt«, aiid iheee bundlefl are, by cbehelpot connective lisBue wbicb cam» 
DO klocMlveawls, woven iuto an iiitricale network or B[ioDge-woric, which 
forn» tli« greater part of tbe wall i>l' Itie vealricl«. Imnitidiateljr undvr At 
[WricKrdiM coating, oooMatiug of a layer of e]>illi«li<:iiil {ilatea raUng on a 
fioanectivii-tinue aiaa, tbe mutcalar tbsue fornu a lliin coiitinuoua ■baet, boi 
wilbin thw it Kpnads out inta a sponge work, tbe n>e«beM vf wliioh pniwDt a 
Iiibyriiitli of i>iuwik«« voiitinuouH witb the caritjr of the vi^niriclr. Tbe baa 
of this spoDge-work, varying in tbleknea* ani], ibougb iipimrvtitlv irrvgular, 
amogea on a definite tvMna, oonmt of buudl«» or miiKuUr lil^rw united 
br oonnwtive tJMiiv, ana are coated with tho itanic endocardi*] racmbnuc 
(flat epitheliwd plitt<'« ratling »u a connective- iimuo bam*) that Htm tbe 
cavity of the ventricle nitd, indeed, tlw whole interior of the henrt. Thr 
cavity of the ventricle, in other wotcIm, opon» out into a Inbyrinlh of jwii'Mgiii 
reaching nearly to tbe surface of the ventricle. Wh^n the veniriele ■ 
dilated or reluxc<d, blood flows freely into am) fills this Inbyrinib, batbing 
tho ban of the sponge-work, whicli, in the a)«ence of capillBriea, de|wnd oo 
thu hloud for their nourishment. When the voiiiricic contracto. the blixvl 
i* driven out of this Inbyrinth a« well as out of the central cavity. Ht-iior. 
the ventricle wbon dilalod and full of blood is of a deep red color, «hi-ii 
oontracled and empty is extremely pale, having little more than tbe color of 
thr muscular fibres themselves, which, like siriated fibrea, puMcsa in their 
own aniMiiance a certain amount of hicmoglubiii or of myohiSfnatiu. 

The much thinner waits of the auricle OoiuiBt of a much Ibiiinnr network 
of similar librcM uuiit-d by a relatively lat^r quantitr of coniKclive ttnue 
into a thin sIhwI, with the pericardial membrane on tbe outside mod tbe 
cadocnnliHl metubrane on the inside. Tlie libra* bnv« in the auricle a much 
groHtor tendency to be branched, and many, oaaning to be tpindlo^baped, 
become nlmoxi tttctlale. Among the obwurcly nLriate<l but atill striated 
fibres arc found ordinary plain mu*i!ular HbnM which incrcaie in relative 
ourabor along the rmitii of tho veitis, rimw c«vmi, and pulmoiialce, until at 
80HM litth' dintancv from the )it-jirt jilain muscular 6bres only arc found. 
Bloodvenots are absent from the walla of tbe aurieW aW, 

In Um bulbil" nrl(■^i•uu^ mixed up with mtii-h conncclive and elastic 
liasue, are found fu*ir<irii) fihro' which clo'e to the vcntHole >m striated und 
form a thick layer, but at A certain distance from the ventricle luee their 
atrialion. or ratbor become miied with plain muscular iSbree, and form a 
thinner layer. 

$ 1$8. Ju tbe namnal. both the ventricles and the auricles are formed of 

buiHlIeaof muscular tissue, bound together by connective tissue, and arranged 

mon wpeciallv in the ventrictee in a very complex system of aheela or bands 

ibpoeed as spirals, and in other ways, the details of wbicb need out detain 

_^ In ibe auricular Appendices and elsewhere, tbe bundles form irregular 

■networks projecting into the cavities. 

The ounneciive tiaoue binding the muscular fibred t4;^ther, unlike the 
atfnspoodiug ootinective timuc tu the frog's heart, is well supplied with 
bloo<)vcsMils belonging to the coixmnry aiy*tcm. This ouiincdivc tivuc forms 
on tbe inner surface of the cavities a couliouous sheet, tbe connective- tissue 
basU of the fiat epithelioid cclU of ihe endocurlium, and on the outside of 
the heart the viaocrat tayi-r of the pitricanlium. 

The hintoliigical unit of tbi^e miiKt^ular bundles is neitlier a fibre nor a 
fusiform fibro-ecll, but a more or let* columnar or prismatic nucleated cell 
generally provided with <mc or awn short, broad prooessw. [F\g. 90.] The 
nucleua, wnich is oval and in general rv^emblos one of the nuclei of a #tnaled 
fibl«, b placed in about tlie middle of tbe cell with it» long axis in the line 



■ir nil lIUHi. MUlK IK i UfHal' 
ntimti. »ni.titi%. On lbs ttshl, (ha 
IlulUur ll>« ■g|».-«la vrlb wllh Ui^ 
iiucIpI on i-iMHliil Moicwlul 41a- 

of tbi' luDg (liiiDxtttT af iIk- cell. The coll IkmIv, wbicli is nut liixiiiiind by 

any ilvfiiiile niirruti-mmii, \* KtrinUNl, tti»ii);h (riiocuroly <o, ncriMS tbu tuBg 

■licinntrr iir tho c«ll. llio Ririaliuus m in n 

skeUul musok Kbre being diH> to iho tUivrna- 

Una of dim mmI bright baixla. As in lli« fn^'* 

bmrl, i;rutiul0' are IWi^nenlly abundant. <th' 

acriiriii^ ihe stnatimi, whicli iiHlecd tven in the 

abdCfM^eot' umntileB ia never so disliticl as in 

ili«flbn8<»l'skel«Ml miuclw- Sucbucell is at 

«ftrh end joiiieil by reinent Biih«laiic« to HimiUr 

oelU, no<l a n>«t •>( mcU celU i-imstituicfl n 

Mitliac "{rmriitary fibre. Heni.-^, a cardiac 

flbra b II fibn- !<triMt«<). but wtthoiii iinr<!i>lomma, 

mm] divt<)r<l by tiartiuon* of reJiieiit 6iib«tBnoo 

tnu> M>tiH>» bat rlou^itvd ilivi«(<>iu or culls, each 

anntainiti^ a nuclMW. Many of tli« nib in a 

tibro bavv a uliort bmod, Ulvral pruceai. Buob 

It prac«M b uniti-<l by cMnent Mibn«Doe to m 

lirailar pr»i;tw> of n wll twionging to an 

adjoining tibre: and by tbo uninu of a number 

of tJirM |iroocHu-«. H nniitb«r of parallel fibm 

ar<* forni^Nl into i\ uxixrirbat oluw nvtwork. 

Kacb buDtlle of thu carditu' miidcular tiwuu in 

thus itcelf a iiatwork. THmo bundlca ara 

Airlbvr wovirn into ni-tworks br oonnoctive 

liaeu« ill which run car>illarioe anil liirgor blood- 

veaaels ; aiid dhoeu <>r oiindira comiMMed of such 

notworlu atv arraii^'^d, tw we have said, in a complex manner both in th« 

auricle and ventricle. Hencu, the miucular dub^iunoe of the mammalian 

hnirt is, at boitoni, on exoeediogly complex network, the elem4:nt of which 

i« a wtniewfaal branched nncleatetl striated coll. U may Iw rvmarkud Ibat 

tbe " tnusculi pectinali " of the auricle and tho " coliimnLV carnca; " uf tli« 

vvntricle suggeil Ibe orixin of the inammaliau hunrt fn)ii] a iniiw4ibir 

Ubvrinili like that of the iWi|t*s ventricle. 

At ibi' cifinuienceiuvnt of tne great arterieii thin [icoulinr eardiac muscular 
tMMue onucH abruj>ily. beinff refilamd by tbn ordinarv iitructurei of an anery. 
but tbc •triuted miimiular Bbrea of the anricle may lir traood for aome du- 
taocv al»n|[ bitfh the veiitt oavie aatl venie [lulmonalcs. 

tTniler tb« endonmlitini are frmwintly prw^nt ordinary plain muscular 
flbrw. and in koidc cawii )>«cul!ar ciOl* arc tuund in this situalion, the uelU 
nf ['urkiiij'-, which »r>- intcreitlinf; ninrpholngicallv becaUK the budy of the 
ndl anxiad the nucleus is nriliiiary clunr protoplasm, while the outside b 
■iriaiM] lubatanoe. Plain muHcular fibri-a arc wiid al*u to snread frum the 
oadiinintium for a ccrlnio clistMtc« into the nuricti to- ventricular valves. 

ilSS. Tlui nrrTTM of tho kimrt. The diMribution of nerves in the heeut 
varii-a n guttil Ai»\ in diflerent vcrli-hral>- animals, but neverlhele^ a k;eneml 
)>lai) i> tniit« uT IwH evident. The vrrtclirate heart may be rcpirdetl m» a 
muaculnr lube (a niiiglu IuIm>, if lor the m'>riient we disrettanl the complexity 
(if a double rircnlation occurring in tlie hi;;her noimals) divided iuio ■ wrlea 
(if ciiaitilipn. sinus vetioeus (or junnioii of great veins) — auriele, rejitriole, 
and bulhud (or cuuus) arteriosus. The nervm (with the exception of a Hmall 
or-Tvc which in aotoe animals reaches the he«rt by the aorta) enter the heart 
at the vut'iuB end nf this tube, at the sinus renoaiu, and pa^ on toward ibe 
arterial md, diminishing in amount as tbey proceed and •lUappeunng at tin 
aorta. ( InDoected with ibe nerve tibree thus paniog to the heart are grou|n, 




At ench beat llie time durip); which the <.'ont«nU of tlie left wutricle are 
injecwil iiilo (he aurta U, tu we hnvt leeu (.^ 13t>). very brief. The expnu- 
sion of the aorta b very sud^ten, and the ocaiaiian of that cxpaimon is alao 
very >u<)den. 

^ow, wlioti lliiiil U l)«iiijt dri\Mti tvith o^t'o n stviuly preniire tbrtHigh an 
elastic tubt! or n syattm o£ ehmtic tiibvH, levcnt placed On the lube will 
de*cril>o curvtw iiidiating VArintictnii in the dtnmctvrof th« (iibclf lUc iiifluw 
int<.i the tube bo vuddcnly Rtop[)cd, u* by sharply turning a etop-cock ; and a 
comjntriitoo of Icvcn plovud at diflcront distancn ffx»iD lb« »top-cock will 
ahavr thill thoie variaUoiM of diamuter trav«l down the tube from the stop- 
cock in tho form of wavoa. The lever near the stop-cock will lirstof nil Dul, 
but t>pce<lily begin to rlsa iignin, and this subflcqueot rise will bn followed by 
anqlticr thil.afler which there mny be one or more ancceeding rises and fnll«— 
thiit is. oscillfitions — vi-ich dccreaaing amplitude% unt^l the fluid conior tn rest. 
The lot-ore further from the slop-cock will describe curves, similar lo th« 
aIiovc in form but of tese amplitude, and it will bo found that these MMrtir 
somewlial Inter in time, the more so the further the lever is trom the stop' 
cock. Obviously Ihese waves are genemted at or near the stop-eock. and 
travel thence al<in^' tlie tubing. 

We may infer that at each beat nf the heart similar wavea would be 
geoeraitMl at the rout uf tlie aurta upon the sudden cessation of the San- IJroiu 
the ventricle, and ivoulil travel thenc« along the einittie arteries. The facia 
tJutt each beat is rapidly succeeded by another, and that the flow wliivh sud- 
denly ceusex is also, by the nature of the ventricular atruke, suddenly geo- 
eralcil. may render the wuvoi more complicated, but will not change Uieir 
essential nature. 

Tlic exni-i interpretation of the gencnttion of th««o wavex is perbajM not 
without diflieulty, uul two factors Mxm of esneciul importance. In Ihv first 
place, iia we have already more than once said, when a rapid flow isauddenlv 
stopped n negative pretaurc makes its appearance behind the column of fluid. 
Id a rigid tube this umply tends to a reflux of fluid. In an elastic tube iti= 
eflocte are complicated oy the second factor, the ela^itic action and inertia of 
the walls of the tube. Upon the sudden oeeeatioD of ihe flow, the axptttisioit 
of tlie lube, or as we may ut once say, of the aorta, ceases, the veeael becilia 
to shrink, and the lever placed on il^ walls, as from .1 onward in the pube- 
curve. This shrinking is in part due to the elastic reactiim of the walb of 
the aorta, hut is increued by the " suction " action of the negative iirtHoie 
siioken of above. In thus shrinking, however, under these oumbined cutseft. 
the aorta, through the im-rtia of ila walls, overshoota the mark, it is carrie<l 
beyond its natural calibre — i.e., the diameter it would poase w if left to iudf 
with the pretturc inxidu and outaide ^ual ; it shrinlu too rou<Ji, and ooiuse- 
*e(]uently beeins again Co expand. Thii> secondary expatuion i^ taking for 
simplicity take a nulMi-eurve m which t)i*^ ho called pre-dicrotic wave, B, is 
ubtHMil or inconapicuouN ) cau^tc* the HM;uudarv ri»o nf the lever up to 6^— that 
is, the dicnitic rim.*. In thu^i cxpunding nsiiin, thv aorta leiida to draw back 
toward llio heart the (Hiliimri i>f blood wliicl) by Iom of momentum had oomo 
to nvl, or, indeed, under the influvncc «f tho negative preasure ()>oken of 
above, wim alrviidy undcrgi>inf^ ■ reflux. In thin sccnndary expaneion, more- 
over, the aorta is by tho incrii-i of ii.-< wulU, aidud by thai of the blood, again 
oarriet), w to jjK-nk. beyond ila mark, wi ihnt no sooner hiis il become ex- 
panded and filled with fluid ft a certain extent than it again Itegins to shrink 
u from '_' imwnrd. And thi* shrinking may in n similar manner lo the first 
be followed by a further expansion and shrinkint', giving rise to a |Mist- 
dicrolic wave, or it may be lo post-dicrotic waves. A.OU the Mocotsivi- 
changes thus inaugurated at the root of the aurta travel aa so many waves 





kliMS the vtariaJ mt«iii, dimiiiisliiiif; ns tkey go. It will be oboen'et) ihat 
fitr ibw ileTetoiiiiUMit of tl>p«e itnvee a oorUuu quality iu iho iralls of Uie tubing 
ta WTiC t— TV. ThetulwiniiM licaucb fts powMSeB when at rcfll an o|)ei) luuten; 
lh« walls uuK be of such a kind thtX the lube- reniaiiia open wlten eiuptv — 
L *,. wheo Uw atinca|iberic pmaure is equal innidc and •nilaide — A that vdeti 
it ahriala too macb it exptUMlR again in Mrivinj^ to re^^n U» naiiiral <-iili1>rc. 
Thi> w« have K*a lo be a cfaaraeteriBtic of the arteriea. A culliifMJbU- lube 
of lb'' '-.lae will not ibtm ib^ |>li«uotiK-na ; audi a ttilw wlioii ihcxtup- 

eoek ' .1 1 i-ollnpws and cuijitit* ibH^lf. vouliniiiug ii> be cDlltiiAii] witlf 
out Msv «Dwft U> ci|inDil nuulD. 

In tfw above ri|tlBiiHti»fi nu meutioii had been made of tli« clnainL' of the 
Mialliinir valvw; tv« •ball hnve in ^lenk of lb««! ii litllo Inter nti in rvfor- 
ring to ibe ppn^icrotio wave, und nball wee that, under lh« vi«w we hiive just 
giwB, iht c\tMag uf the !>eiiiilLiiiar valves b to bo rci^rdiNt rather lu tliv 
•flbcl tban tli« cauw of the dii:ti>tic wave. Maay nulbont. buwevitr, give no 
fanaravetatlon uf Ibe dicrotic wave diflenut fnim ihiit detailetl above. Tbus, 
h it beld tbat Ibe primary tlirinking Ironi .-I onwani, being brougbc to bear 
«■> tW (Mlamn of blood alnady come to rest, in bee of tbo gnat preatnre in 
fVtnt, drivt* ibe blood back aeainM tba wmilunar valves, thus clwiof* litem, 
aod that the iaipncl of ttic eolumn uf blood against tbe valves siarU n new 
war* of espaniion, nhicli ifinforcini; the uaturnt tendency of tbc oImUc 
wsJIa to expand again aficr lliHr prlranrv ehritikint;. produces the dierotle 
mn C On this view, it if the blood dnvcn beck from the valves whicb 
•xpUMb tbe artery ; on the view given abure, it is the expanding artery which 
dmtrrs ibe blo<id baek townrd ibe valveH. 

MoteovtT. fjuite olber views have been or are held ooneemini; ibiai dicrotic 
wa%-c. AevirdioK t" many authora, it is wlial k called a " ivtifcied " wnvc. 
Tlma, «brn lite lube nf the artifteial niodcl bearing tnu lev(irt< is blocked jnat 
bwyunl tbr far lever, ibe primary wnvu is wen to beaoconiiuinW byafecond 
waw, wbteb at the far lever in wi-n rlotw tu, ami often fusecl into, the priniair 
wan (Fig. h3, VI. a'), but at the itcar tever is at some distance from it 
(Fy. H3. I, »'). living the further IW)ai it tbo longer the interval between Ibe 
Urrr atxl ibe block in the lube. Tlu) seennd wave t* evidently the primarv 
wave reflected at tbo block and travelling linckward toward the pump, ft 
thaa, nf eour^, pospes the far lever before the near one. And it bai) beon 
ATfon) that the dierolie wave uf tlie nuUc is really sueii a reHectetl wave, 
•tertnl either at the minute artfries and capillaHe*. or at the points uf bifur- 
«atioo of ibe larv'er arteries, and travelling hnckward to the norta. But if 
tUs wervlbe eaw. ihe distanee between the iirimary cmt ami the dierulic 
cXHt ougbt to be less in arteries more distnnl fmui than in iboae nearer to 
tlM* Iwnrt, just as in the artificial scheme the reflected wave ia fined with a 
primary wave oear the bl<»ek (Fig. i<^, VI. H o. n'), but becomes more and 
man sefanued from it the further hack loward the pump ite tract.' it < Fife. 
A3, L 1 M. <>'). Now. this is not the caw with the dierolie wave, f'an-ful 
imawirrmrnts abow that tite dislam-e between the primtiry and dlcmtic c-rcsla 
>• aillMr gmter, or ecrtainly not leas, in the Knvaller or more distant arteriea 
than in the Inrger or nearer oitea. Thin feature indeed prove* tbat iba 
dicrotic wave canniM l>« due lo reflection at the |ti-ripherv, or, iniltx^il. in any 
way a retrogrado wave. Besidea. the niullitadJnous |ieriplieral division wuultl 
mtder one large periphically rvAecied wave impoasibfe. .\fn>in, the more 
rapMly ibe primary wave i« ublilerated. or at leiitt diminulwd, <>» its way to 
tba ptripbery, tbi^' Iom oooapioiiou* should be the dierotio wave. Henc* 
iaoaMM exienfibility and Inereased elastic rtnctioit of the arterial wxlla 
vbfafc tcod to Use up rapidly i)h- |)rimary nave,*li€iuld nlso IcMen ibe dierulia 




vmw, Btil DM n nmtlcr of fact Uinw conditions, ih we have Mid. ure fnTur- 
mblc U> ihc proniiiicntT of the dicrwlic wave. 

Od tlie other hand, thitw nnd thv otWr condilioRE which fiivor dicrotiain 
in the pulso aro cinctli' tho»c which would favor such a develofiiDeat of 
gc'ondiii'T waves ns hoe dcvd dcH^rituHl nbove, and their absence would b« 
unfavoriihio to the ocrurrcnco of eiich wave*. Thus dicrotism in les iiiur][«d 
ID rigid arteries Tsuch ns thoM of old noopio) tban in healthy elastic ODU; 
tiw rigid wall neither expands so readilj- nor Bhrinlu so readilj, aod heme 
does not so rendily give riw to such secondary waves. Af^in. dicrotiaiD ia 
more marked when the mean arterial prcssure is low than when il is bigh ; 
indeed, dicroiism may be induced when absent, or inoreased when slisluly 
marked, by diminifihing, in one way or another, [he mean pressure. Now, 
when the prenaure is hJKb. the ai'teries are kept cuntinuallv niueb expnnd«d, 
and are therefore the le&s capable of liirther ex]»ausion ; tliut ia to ny, ar». 
so iar, more ri^id. Uence ine additional expausioD due to the aystolo ia iioC 
vcrv great ; there in a lew teodeooy for the arterial wulU to awiog backward 
waa forward, so to speak, and hence a lens tendency w the dcvelapm«ni of 
Mcondary waves. When the mean preasuro is low. tb« opposite itata of 
things exitiiH ; tiuppuainj,'. of counte, that tlie ventricular etn>ke i* actcquMcly 
vigftroutt ( the luw prcwure beiti^- duo. not tu diininiiihed cardiac force, but f > 
(liminixhud |>tripfaeral resiataiiOL-). the relatively empty but highly di.-xriii^iblc 
irtvry in rapidly expanded, and. fallinf; rapidly back, cnlcrt ujkjh k wcond- 
arv (dicrotic/ expansion, and rvuu ii third. 

Moreover, the .name principlis may bi^ anpliod U) explain why anmctimc* 
dicnilivni will apiwar murk<.-d in ii pHriii-iilar artery while it remains little 
narked in the nwt of the Hystem. In *!X|iirrin)cD[ing with an artificial tubing 
euch as the arterial nitxlel, the physical cbimictcn of which remain the 
■anio throughout, bulb thu |)riRinry and the sccoodary wnv» relaio the same 
obaracters as they travel along the tubing, save only that both gnulually 
diminish toward the periphery ; and in the natural circulation, when tlie 
vascular conditions are fairly uniform throughout, the pulse curve, as a rul«, 
poaMsses the same general characters throughout, tave that it is gradually 
•• damped off." Bui suppose we were to substitute for the lirat section of the 
tubing a piece of perfectly riKi<l tubing ; this at the stroke of the pump, uu 
account of its being rigid, would show neither primary nor secondary ex- 
pansion, but the expanding force of the putup's Htroke would be traniuilled 
through it lu the second elastic secljon. and here the primary and aeoondary 
wavM would ut once become evident. This is au extreme case, but the aame 
thing would be aeeu to a leas decree in passing from a more rigid, that ia, 
lam cxtctuiible aD<l elastic wotJon, to a less ri^d, more extensible and elaxtlc 
Mction; the primary and secondary expam^ion^, iu npice of the veneral dump- 
ing «flVt, would suddenly increase. Similarly in the living Doily a pulito- 
ciirve which, no long aa it U travelling along arteriu in which tlw nu-AH 
prcsaure ia high, and which are therefore praulicully ^mewbut rigid, is not 
markedly dicrotic, may l)ec(imti very markedly tlicroiic when it <umn to a 
|Hkrtini1iir artery in wbidi the mean ]>reMture U low (auil nc shall kc pres- 
ently that nuch a case may occur), and the walls of which arc Ihervforc for 
tltc time ttcing relatively more diiiteniiible ihau Uie r«cL 

littslly, wo may recall Uic observation made above (§ 141) that llio curve 
of expaiieion of an elastic tube is motlified by the preseura exerted by (he 
lever emplovod to nK.'or<l it, nnd that bciicc, in the same artOfy mid with the 
same in^trnmcnt, the nine, form, and even the special fcjiiures nf the curve 
vary according to ihe amount of pnwmrc with which the lever is pmssvd 
u{".>n the artery. Accordingly tlic amount of dicrotlum apparent in a pulse 
may bo modified by the prcmurc exerted hy the lever. In Fig, 80, for 


TOE rULSK. 289 

iaaiBMtt, l)ie dicrotti' wave it moro ovidont iu Hw muldlo tluiii iti tlic U|>per 

$ 147. Tbv pr»-<licn>tic wmvv (nmrkctl A on Pljr. HI, nod od seveml other 

of tbr pulw-^tmcs), which pit-Mdcv iho dicrotic wave mid u still mure 

Tarisblv Ihmi thai wkvo, beiug soniviinii-s slight or oven invisible niid soiue- 

timM ooHpKilMH, has given nw to miifh controversy- In the iot«ri>retatioD 

of tlM £erntio irav« given in the nrcccdiii]; imni^riiph it wu slatM] tlmt the 

OMBlIr* praMure developed on the eesaatioo of the flow iu lh« rear of the 

CDMBUiar blood, kd bjr iuelf to a retlui toward ilic ventricle; and it hn* 

hrra 9afgm,ted that at thif reflux meeting and elosins the aemiluaar valvi.» 

•buta a BOiall wave of ezpnnsiou before the larxer dicrotic wave )uu> bail 

tisM to develop ii«eir On thia view the seiniluiiarvaJvei would be actuull}' 

dflMd Ikefore the ocetirreoce of the seoondary dicrotic expansion of the 

arl«n»l nails, though the larfft^r, more |M>wer(ul reflux of thi* lat«r event 

mnu rvuder tlw tlmure n>ore L-oinplete, uud iu duiug so prxvihlv gives rise 

to ibm peoond muud. Aecordinu;. however, to tiie aeicoitd view xivui ia the 

MUM Mragraph, which regard* the reflux due lo the Kbrinlciug of the 

arterjr to fooe of the great pntwire iu front as Krinly closinz the semilunar 

■BlTaa,«lid U thus starting tlie semniUir}- dierutio wave ofexpaDiion, the 

film dMiag of the somliiinar valvCM must take place bofbra the bc^nning, 

Ml dariiu the dev«)i>po>enl i>f the dicmtic wbv<> ; it is Mill poi^blc, however, 

ima OB tail view, a* on the otluir, to mpjiotu; that au antccttdcal refiux, due 

t* A« iMeative preanira wioccediDg the c'cssation of fluv from the ventriele, 

dotes U>» valvM and Utrts the pr^icrollc vravc. But iliv matter is one not 

jM bevond tht' flago of coniroverey. 

)t40. In an anarcrotii- y\i\fV the lint rise is not the high4«t, but a seeund 
rm 11, Fig. Ml which f<>lliivt:> and is sijpnnitrt! from it by n notch u higher 
tkBB,or at least as high, as ileolf. Such an anari-rolie wave, though it may 
■wdoes be produced ieni|xintrily iu healthy pentoiM, is generally MW 
(bud with diseased eundiiioits, usually such in which the arteries are ab- 
Mnally f^^i- Iu des«rribing the ventricular iyutule, w« spoke of the 
■■m* vUbin tlie ventricle as reaching its tuaximuin just before the open* 
■gof tba ■emiliinar valves; and this is appareutly the nornuil event ; Imt 
iWn are ctirvea whicli seem to show that aller the fimt suihluo rise of 
fnpurs which opens the valves, fullowei) by a brief Uwcning of pressun, 
efcich appcara on the curve us a notch, the preeaun: may again risc,nml thai 
Its putBl higher than liefure. And u similar curve is •nmeiimri) il««cribed 
\if the Auot-to-hai-k diaincter of the ventricle. The tiyalole opens the valve 

■ ilvSf* with a hunt : this i* followed by a slight relapse, and then the 
ntdt, stimgthoning a^in, discbatget the wholt^ of llie vriitrici>lar conleolt 
klalM aorta and »u brings about a tardy maximum ctjinniinn. And what 

■ tliin tlarteil in the nuiiM tranll onward ovrr the Btlerial system. It is 
<Unih to ter hiiw tltew anacrotic ercnts cnii Iw pnxliiM-d. excupt by a 
Riiaih irrrgulantj io Lbs vcairiailar •vsiolv; uid. indeed, the anacrotic 
pobt is fn-i|uenily Hwoeialed with some iliMtnw.- or defect of iliit ventricle. 

iU9' l'ri*ou4 pultr. Unitor n'rtain (-ireum»tnncn ilie pulse may be car- 
■W •■ from the arteries ihrriiigh tbr uipillnrics into ihc veins. Thus, as mc 
liall sea later on, when th« salivary eland is actively Meriting, the blond 
nnyiiaue from the gland through the veins in a rapid pulsating etn.-nui. 
Tfat aerroua events which ^ivc rise to the secretion of ualiva, lead at the 
•Bs tline, by the agency ol vasomotor nerves, of wfatrh we wtll prcHcntly 
i|nk,t» a dilatation of the small arteries of the glai>d. When the gland ts 
Ufrst \iw ininuiv arteries are. as we shall see, somew hat ooustricled and nar- 
iMtd. and thus contribute largely to the peripheral resislanoe in Ihe part ; 
Iki* psripberal rtsistaure throws iuto action tbc elastic pm|ienics of tlie 

240 THK VASCfl.AR UKCHASISM. ^^^^^^P^ 

SRUlI tutcrif* loAiliii^ to lUv )clai><), nml l)ie ri^miiiint (if the |)iit>e renctiiiig 
tliCM' nrU'-ric's i,*, lis wc Ix'forv ex|)l)iiiM'il. tiiinlly (K-ntriivol. Wlii-ii tht? miauie 
nrtvrit^ nn; ililiiti>i), tlieir nideiinl cliunutils nllnw tlio Muml (o lti>w iitoro 
c3«i1v ihrotij^h ttiviii iiiiil with leav frii;ttou ; Ibc {H-ri|)hcral n'^iiitiiiirr wliirh 
thi-y normiilly itffvr in llms Jf.-wticil. In Gpn*v<^ucn«- of tbU tlu) daolicitv of 
thcirall» of lliv Hmnll iirtcrii^ m brought into })Uy to » Icn «xU.-iiI tWu 
beforo. tind tlien? «iiii>11 BrterieM cotMO to <)o tlifir ahnro in dcstrojri'^ ^ 
pulse wliirh oonics dnwti to tboin from the lnrfi:('r ancrim. As in th« case of 
the artitidal niod<;l, where thu " |>i;ri|ihrriil " lulling i« kept "]ii;ii. n»l <'tniiigli 
«liuticity i« tiroiight into jility to convert Ihc intermit t«ni Krieriiil How into m 
continuous one. nnd the jiiilw which rnichcs the 3irt«ri«B of the giniiil peuncJ 
on through them nnd through the ni^illiirics, iiad U <:oiitinucd un into the* 
v«iiia. A Bimilnr vcdous pulee ii also '•onietimea seen in other orvaus. 

I'arvful trneingH of the grent veins in the nenghborhood of llie liearl shnw 
elevations and deprcanons, which appear due to liic varialtansof iotra-cardtsc 
(nuricular) prewure. and which may, perliaps. be spoken of as cooslitultny 
n " v<<nnu!i pulse." though tliey have a quite ditferent origiu from the vraoue 
pillie just dcHcribe-l in the salivan- glaml ; but at present they Deed further 
eluciiMtinn. Iii uiises, however, of insutiicieney or tJie tricuifKd valves, the 
•v«lolv of thi^ ventricle makee itoelf disliuctly felt in the great veiits ; uiil a 
^fisliMiiion travvlliiJi: backward from the heart beoomee very vUible in the 
veiiiH of thv neck. This i* xotuelttncii :<poken of lu n venoUM ptibie. 

Vnrintion!) of preixure in the ^reat veiii», due to the rcKpirnlorr mor^ 
nienls, arr nlno mnietttuea iipoken of an a reuoti* palw; tJiv nnlare (if ihew 
variation* will bn uxplaiucd in treuliug of rcspintioit. 

The Redulatiox akd AoArrATioy or the Vascular MecnANtoM. 
b The Itfyufatlon o/ the Bmt of the Heart 

§ ISO. !v> Gir tlic fiu-ts with which w« have hnd to d«nl, with the exevptioa 
cf tlw heart's beat itaclf, have l>eei) simply physical facts. All the ^vMntiftl 
pbenomcna which we have studied iriay he rrjiroducFd on a dead modfll. 
Such an unvarying mechnnicid vascular system would, bonevor, be itaelenio 
a living body whose aclionn wen? at all complicated. The promiodnt CwtoK 
of a living mechanism is the power of adapting itself to cbangea to iu 
internal and external circumstances. In such a svstem as we have sketched 
alMive there would be but scanty poircr of adsptittiun. The well-construcMd 
machine mi^hl work with beautiful regularily : hut its regularitr would be 
Ha tleBtructioD. Tht? Dame quaniitj of blow] would always How in the ttme 
•teody BlroaiD through each and everv tissue nnd ori;un, irrespective of local 
auil general nanta. The brain and the stuTuacli, whether at work awl 
mtvling much, or at rest and needing little, would receive thetr ration of 
IdiHM). allotted with a pernicious monotony. Just the same amount of blood 
would imns, through the skin i>u the hottest lui on the coldest day. The 
oaoon of the life of «very part fur the whole period of its exittence would 
he funii.-*hed by the inborn diameter uf iia blood veateli), and by the uuvaryiog 
motive power uf the heart. 

8uch a rigid svslem. however, does not exitit lu actual li\'inf; beings. The 
vascular mf'hniii.'U] in all imimabi in which ic is present is capable of local 
and general modifKntiouM. adapting it to local and nocral changa of cir- 
eiimetaiics. Tbv»' Ri»diticntir>n!< fall into Iwn great duns : 

1. Changes in the bearl's beat. These, being central, hareof eoursom 
general edbct ; they influence or may influence the whole body, 




'2. Cluuig«a in ihv [icripboral n«ii>iiiuc«, <lut' lo varinttuii-a in the culihre i>l' 
Um miootr iiri«ri<«, brouglil abuut by Hut agtacy oT tbdr contractile tnii*- 
vnlar o<uit«. TIk-m ctuuigM n»y m either luca), HfliM-tiuv a uarticiilar 
vawulnr «m uuly, or g«Dcnl, iflectiiig all or nearly all ihe olooilvotitelt of 
the body. 

TIkm twodaaMs of events arechieHy ^vernrd by the nervoiu «yMo(ii. It 
it bjr BMUs of th« iKrvouB «\vtcn) thnt ibi: h(-nrl'» iHrnt nii'i llie <.'nlibr« uf 
iba uiaiile artcrice iirc brougiil into rolalioii with onvti nlher.aDd with almoM 
•vcnr ]art of llie Wly. It in by mtviu of the ntni-oiiF »yntm acting cither 
on lb« heart or on the bdwII arteries, or un both, Ihnt a change of circiini- 
wumrtB aJStctinz either th« whole or a part of the l>ody is met by compeiiwiling 
or rt^litive cliaOf^CB in ibe flow of bloo<i. It is by nicaiie of thv n^'rviius 
mytUta lliat an orfcan bu a more full supply of blooil when at work thitu 
wkeo At r«M, that the tide nf blouil (hroucli the sltiD riaea nod ebb« with ihe 
riw and fall of the tttiiiitralure of the air. thai the work of the heart ia 
leiapered to nieel the strain uf overfull arteries, and that the arterial ^•atee 
open and ihut u> the furue of titc central pump waxes and wanee. The 
■tody '-f theae ebaDgea becotges. therefore, to a large extent a study of oervoua 

The cimilaliou otay aim hr. iDmlified bv eventa not belonguig to either of 
the abow two Flamn. Thug, in tbii or ifiai peripheral area, Hianges in the 
otpillary walla and the walU of the minute artenea and veina may lead lo 
■a inciuw of tl>r (vndencv of the blo<Kl corpuiK'Iea bi adhere lo the vascular 
valll. and to, quite n|>art from any cbnnj^ m the culihrt) iif ibti bloudviawdf, 
nay Wd tn increiue of iho [icriplicrnl n-nt^tanoe. Tlii* in wen in an exlrvni<r 
catc in influRimalton. hui may puwility mt«rvvne to a Inic extent in the 
unliuary oiindilioD of Ihe circulation, anil may aVi hd un<h-r the inHum^v 
of the uervous system. Further, any decided chan);r in tlie (juantily of 
blood aclnallv in cirrulutiuu 0111.M also iolluencc the working- of llie vasmlur 
mechanism. Due Ixnb lhe»-- chaii),-<h^ are unimportant compared with tlte 
other two kindH of i-hiinun). Hence, the (ho nioil important problems for 
u» to study Hre, I, how the nervous syiitem re^ihttai the beat of tbe heart, 
•ad 2, buw the nervoui' »yi>ti-in regulateA tlu! cnlibre of ilw bloodveasela. Wo 
«t1l Rrvl conai)ier the fomter problem. 

Tkf llUtobtyi/ of thf Hrart. 

% Ul. It will b« neccMary dow to take up certain {>ntnt* coDcerning the 
■ninute ■tro«-((ire of ibe heart, which we hnil previously {loriponed : ami 
■inct much of our knowle^))^ of the nervous m«-hani"m of the bent of the 
hisrt is derived from eK|>criiiH'Dt« on the heartJi of I'old-bloodeil animals, 
niorv particularly of the frog, it will be dciirabic to coniiiler these as well as 
the mamnialiaii heart. 

t ittdi/t^ rnvteaiar tisme. The ventricle of the frog's heart H composed of 
miDMla «}>il>d]e-«haped Hbres or fibre-cells, each coninining a nucleus in its 
middle, and tapering to a |>iint at each end ; foinelimes, however, tbe end la 
ferfccd or even hraneWd. Tbeae fibres or fibre-cells, id lact, resemble plain 
ataamlar flbres m\-« that they are somewhat larger and that their nibtitance 
Is striated. Tbe Mriaiion ts due, like the strialion of a striated museic 
Ibre, 111 allvmato dim nnd bright ImmU, but is rarely so dintinct tis in a 
•kclrial lihrr; it ts very apt to lie obscurei! by (he presence of dispersed 
dWtinrl grttTmlfH. which, in niiuiy ciuat ut all events, are of a fiuty nature 
I.ikr ihf ptoiu muscular fibre, the ear<llae miiHculnr fibre has oo dUtinet 


2 12 


A number of ibcM librim nre jninecl bv coment MulkWiuiM Eoto rruII 
buniilcfl, nnd tl»i>i:biiiiclli.-a are. by lh<- belp uf CMiiucctivv tittniv which cttrri» 
no blood v<-«M!t>, wuvon into an intricnU^ network or sponge-woric, wtiicll 
forms the ercnicr piiri uf iho null of thi; veiilriclri. Iraiii«Nlial«)y uiKler tb« 
pericArtlmfcnnting, cuiMxliiig of n Inyt-r of upiihclioid pbilcs restinj; on a 
couocclive'tisiur- bnvix, Llic niuHciilitr liscui; fornit! a tbin continuous »b«ec. but 
within this it spread* out iQto n (jKiiigD work, the iik'»)i<« of which nreecDt » 
labrrintli uf paMSg«s continuoiii> with tho cnvlly of the Tentriclc. Tlie bars 
of thiit apon^fvwork. varring in ihickncva nnil, llioiigh ■p|>ni'cntly irrejcutar, 
urriiu);ed on a dutinile erslcm, congist. uf bundle* of niuHcubtr fliir«A united 
by conuective tissue, and nre coated wilb the same (.'iidoeardial lui-mltfane 
(Ant epithelioid plates rvsiing on a connective- tissue basis) that liuu the, 
cavity of tbe ventricle and, indeed, ilie whole interior of the bean. ThM 
cnviiy of tbe ventricle, in other words, opena out into a labyrinth of iias-^iges' 
rciiching nearly to the eurface of the ventricle. When the ventricle is 
dilated or relaxed, blood llowa ft¥«]v into and fllte ihia labyrinth, bathing 
ibc ban of the apiin^ work, which, lu tbe atiHeuc^ of eapillarirai, deiH-rnl mi 
this blond for their nouriahment. When the ventricle contrant*, the Moodj 
ifl driven out of this liibyriutb an well at »ii( of the central cavity. H«aeeJ 
tbe vcDtricle when dilated and full of blood i» of a deep ml colrjr, wbe4i 
oontmclod and empty it extretnely pale, having littlki more than the color of 
the muKular fibre* ibemMlveH, which, likr MrintiMl fibm, posKMi in their 
ovn Rubetanco a aerttuii amouut of hKnioglobin or uf myohntmatin. 

The much ihiiini-r wall* of the nuricio coii»i*l "f ii mwcb thinner nctworU 
of similar libr<« tmitti] by a relatively larger i)uantily of connective tiasilS* 
intOsUliD Rhcvt, with the jH^ricardinl racnibranft on the outside »»d tbe 
endooaidiaJ membrane on the insiilc. The fibres bave lo tbe aurieJe a much 
snater tendency to bo branched, ntkI many, ecasing to be spindle-ebaped^ 
Moome almost stellate. Among the obscurely stjiated but still Mriated* 
fibm are found ordinary plain inuBculnr fibres wbiob iDcrease in relative 
number along the roots of tlie veins, veme cav%, and pnlraoDales, until at 
•one little diat^mce from the be^rt plain muscular mtn» only are found. 
BloodviMiels are absent from the walls of the auricles also. 

In the bulbus arteriosus, mixed np with much eoonective and elastic 
tinue, are found fusiform 6bres which close In the ventricle are tiriat^td and 
form n thick layer, but at a certain diiilunce fmm tbe ventricle Iohi; their 
Htriation, or rather become mixed with plain miMculor librw. and form a 
thinner l«j-er. 

S 163. In the mammal, both the veiilricltH mid the auriclm nra (brmed of « 
bundles of musculnniMiie,l)[)und together by coiincclivc tiMuc.aad arranged] 
mora etpeoially in the veiitricl<« in a very comjilex Jiys[«ni of aheeti or bundai 
diapOMa us spiraU, and in othi-r ways, the details of which need not delaio 
ua. In the auricular appendices and elsovherc. the bundles form irregular 
networks projecting into the cavities. 

The connective tiMiic binding the muscular lihru' togolher, unlike tbe 
oonespunding connective tissue in the frog's hciirt, is tvell supplied with 
bloodvessels uolongiDg to the eoronary system. This cunneetive tissue fornn i 
uu the inner surface of the cavities a continuous sheet, the connective -tbdue 
baMH of the flat epithelioid cells of the endocardium, and on the outride of 
the heart the visceral layer of the pericardium. 

The bUiologiea] unit of these muscular bundles U neither a llbrc nor a 
fuiifunn libre-oell. but a more or lew columnar or priamatic nucleated cell 
generally provided with one or more short, bnmd procebses. [Fik. ^0.] The 
nucleus, wlii eh is oval and in general rewmhlesoueofthenucleiuf a^tnatcd 
fibre, is placed In about tbe mi<MIe of the cell with its long axis in the line 



irvi ai 

or iiiK Hurt, a*» ix t Uiwii- 
ti.'MMI. MiTI»*, On ihr rliU. tfec 
limliior ihc KfaiBte oslli wiib ibdr 
nutttl an alilMlal tonivwhal <1la- 

tt Ibt hmg iliaiwur of ihe «e)l. The c«ll bixlv, whicli ie iiot boiiwled \if 

WIT ilefinito Mrculcmmii. ia uriBl^l, thauKh uWureljr ao, 8<iroaa the loDg 

diaiuKrf of t\tt cell, tlie niHiiUuiu an in ii 

•kakul Btncltf Itbn btiiit; ilm- to itie sltenis- 

tioD of ditt Uti brigbl ImikU. A.i in iIk- frott'it 

iMUt* gnuiihw an tn^ioi-filly nlximlniK. olt- 

■c ii r iiif Ui« •thxtion, Mhicli idiIm-iI uvrn id th« 

ahMDOtof gntRiitM is ntvor to ilimiiu-l an iii 

thm 6br?t ul' akrlvuil idumIm. Such ■ ortl in ui 

«aeh Mid joined hy cemrat wibstAtict tn »iinilnr 

fidli, ■0(1 ■ n>n of i>ucb cell* mnfilitiilrK ii 

cardtkc <'li-ii><.'riliiry fi)>rc. Ilniiie, s cardiac 

6bf«MafibrvalriBtr<l, hill n'i(h<Hit wircoloinina. 

■ed diirided by partiiioni of ninviit »iilNitaiii-i.- 

bibi MHWK'lial elon gated diviMom or <-pll>.4-H<:h 

aMtaJniniE a nacleua. Many of tlic m*!!* in a 

flbra faavo a ahon broad, lateral proocos. Su<!h 

m [nom a la unile«l by ceiii«Dt mbetaiwa to • 

■iiallar fuvii^eitt of a coll WIoDg;ing to an 

•djotniui; libre; and by the union uf a number 

4ir t)M«« iTiK'fw. a number of parallel librca 

■n> loni»i'<l into a ntnewhai oIu«e neiwork. 

flarb iMimllr of ibe cardia« muscular tinue is 

titu* itH-lf a Mtwork. TiieM bundlet are 

tofthrr woven into nelworictt by connective 

tianii ID which nin capillariai and lar^r blood- 

vaaah; and ibiv-i* <ir b II ml lt« composed of auch 

Ol»Bfb arc nrriiii^o), k> w« hare said, in n oomplox manner both iu llie 

auricle sod vi-nlriHo. Heno.v thv tiiu»ciilnr xtibilnniv of the mammalian 

hnrt is, at holl'im, an exceedingly complex notwork, the element of which 

iiBBMMwhat branched nucleated »Inatoil cell. It may be remarkMl that 

■kf>**iilusculi peclinati " of the auricle and the "columaie canK«"of the 

*«a(ric)e aoKK^t t)ie origin of the mammalian hearl from a niuacuiar 

labrrtoth like thai of the iroe'a ventricle. 

At the eummencenient of tlie F;reiit arteries this peculiar cardiac muscular 
tiwiip cmu>e# abruptly, being replaced by the ordinary structurei of an arlery, 
faai tfae stniiied inuwular nbrea of the auricle may be traeed f>ir mime dis- 
uaea along both the venw carte and reoie putmoDalea. 

Uadar the endooardiuin are freaiieotlj preaeot onltnarv plaiii muscular 
flbrea. and in some ea«es peculiar cells are fuimd iu this silualjon. the evils 
flf Puricinj/-, which ure inteiestiug nmrpliologit'ullr hecaose the body of tlu 
call an>utid the nueleus is aniioary elear protO|>lasni, while the outside is 
•Iriatfd (iilmtaiice. Plain miucular fibrM are said also tn iiiirrEul from the 
andof rdium for a oeriatu distance tni'i the aiiriculo-venlriruliir ralves. 

I US. TKf Hfrif nf the hearl. The dintribiition of wrvca in the heart 
Tarios a good daal in diirereni vertebrate animali, but tirvcnhalMa a general 
fiho is HKww or Icm eridunt. The vert«brnU- limrl may be r^ardad aa a 
■MPCfllar tubo (a *ingle tube, if for the monirntwo diaregnnl the oonplexily 
«f ■ double circulation occurring in the highor animals) divided into a series 
«f obanibtrs, sinus venosus (or junction of great vaitu)— auricle, ventricle. 
■wl bulbus <or mnus) arterioHiSL The nerves (with thu eioeption i^a small 
asm whirii in some animiiU ranches the hoart by the aorta) outer Ihe heart 
al ibe voiMMa end of (his tube, at the sinus vonosus. and pass on toward Die 
aitcina) end, dimini«htng in amount as tbuy proceed and disappearing al the 
ODtuiect«i with tJie iMin-e 6bra» thus passing to the heart are group*. 



■mailer nr grvAier, of D«rv« wHi^ Tbwe, like (lie mm fibres, are moat 
abunilaiil at tl>c vctious end (uppMrlng on tin; iK-rv« branches before tlicw 
actually mnvh the heart), a« a rule, become fewer toirard ibe nrlerial end. 
Mid finally disn{)pear, m tlint (aceordiog to mwit (>b«erven; at tbu bulbu* 
(oODUi) artrriiieue they are entirely abMtt. 

Th«M) colleclii>ii» of iK-rve imiIIn or ennglia may ht arranged io grou] 
aceonlin^; to tbeir [toMlinn. In nuinv lower vericl>ra(e0 tber« b a i£at[D< 
riug or collar of gitnglin nl the jiin<<tiiiri of the 8inu« veiiosua witli tl»e aiirielt^' 
where the prinuliTe circular di»p<uiti»n of muscular fibres is mainiuiiiMl ; 
and there if a Hinilar ganglionic nillar at the juiictjou of the auricle with 
the veniriclc. where nlxo there \» HiRiilarly retained a circular diaptMition of 
the muBciilnr tibree forming ihe so-ealk-d mnaiit nurieulari*. And. imleMl, 
iu all vertebrale* two similar eotlcclions of ganglia are more or letn iliatinctly 
proeiit. There are ganglia at the junclioii of the sinue with the aiiriek- nnit 
along tbe entering nerve branches : theee maybe called ihu oiiiuo gaiifilia. 
Tliere are i>lher ganglia at the jiinclioii of the auricle ajid ventrick ; 
may hv nailed the auriculo vciiiricular ganglia. Ue^dc* tll(«<^ Iwo grou, 
tbcri! an- aim) ganglia overthe auricle in cunneotion with nervtw passing frvim 
the Mnu.-> l<> the veniriclc. 

IvHiitlv.aii a general rule. Ihe main nerve branehea and the ganglia are not 
plunged dee]> into the suItstaTice of the bean, but are placed auperftdalljr 
immediately u»d<'r the jieriiardial layer. From the eell.-< and nervw so eitu- 
nted finer brancheit ami lihrm |iaH» lo the ^bstanoe of ihe lieart. 

til the frog land other aniphihia) llie arrangvnicnt ditlere somewhat from 
the above jilun, and therefore needii a special deacrijitiim. 

The only nervea going lo tlie heart of the fmg are Ihe two vagi, riKht and 
left, which may be leen niniiitig along the two tuporior venoi cavie, and 
becoming Ium 1u view at the siniie, where tliey ihm from the surface tu 
deeper part*. Kach vagus is not, however, simply a vagua neire, but, im 
we aliull sec, contains tibroe derived from tlie splanchnic or Hyui[>atltetic sj» 
tem. Ae tlie nerves appnwch the sinus, gruups of nerve cell* becooM 
nbtindanl ii> ooniiectiun with the fibres, and as the fibres spread out nt tb* 
dnus many ganglia are ocaltered among them, forming what ia emlled •■» 
whole the o'liu^ rjitnijUon , or the 'i<iHplio» of llemai: 

From the HinuH the two vagi, leavini; iheir po-<ilion under llic [lericnrdium, 
plunge ititu the heart and run alon;; the bepcum between the auricles, on ibe 
left ndc of the seuluni — one. the auleriur nerve, ptiniiing near«r th« fnini ef 
tlie heart than the other, llie posterior. Several gruu|Di of cells or small 
ganglia are cunncded with the two " septal " nerves thus pa»>ing along tlie 

The nerves reaching the auHculo-Tenlriciilur ring on the anterior tide of 
the heart end in iwii ganglia lying at the \uun! of the two large surKiulo- 
ventrieiilar valvea. 

Front ih<«c two ganglia AiWr/crVf^oji^io, or the i>iineiiya-t<eii(n'cM&iryaHj7/t>i. 
nerve fibres pass into ibe suhstanco of the vcniricle. Nerve cells mar t>e 
traced on tbc (ibrm going to Ibe ventricle for oome little distance, Imt tot a 
ItUle difflnnce only ; over the emler giart of the ventricle, the lower twu- 
ihirds, for instance, the nerve 6brfs are free from nerve cells. 

Thus, in the fro^' ihero are two main ganglia— sinus or liemak'a gangUoo, 
auriculo-venlrieulitr or Itidder's ganglia. From lUe former there pass, on 
the one hand, ^'altered librcs, in connection wilh which are amall groupt* of 
oclb. to Ihe auriculnr vralls, and to the sinus walls ; and, on the other hiiod. 
llie two main nerves running along [lie eepiitni, tn ciuinection wilh which 
are omall gaii];lia which may lie enlled "seplul " gauuliu. From the latter, 
Bidder* ganglia, fibres uDaccompanietl, except fora uTiort distance, by nerve 




to lb» Mihttitnor of tbo vrnlricle, Hn<l jxiwibly to tliv bulliu* 

In Ui« mKmnial tlw nrmnf^Ricnt nppeara to conform nioro cliwuly tn lh« 
g wn i« l plnti dncribt-il uliovv. Tito «i-vcnil vtinlinc ncn'n. from thp HjinjiK- 
tbttio cnun, lo^etlicr irilti ttniiii-liM frum the viigiis, includtug Hbrm from ilia 
rwomnt Inrytifsenl, rnrm the supcrlicial and deep card iiic plcxuMs below 
•ad beoeHth the urch of Ihc aortx. From these plexuora fibres nr« dia- 
tribaied to tin supenorveDB cuva nod tu the pulniuiiary veins, and thence lo 
ttw mrii>u« jtmrta of the lienrt. Gaofflm are abundant on the euperior rena 
oiTM and are also found on lli« pulmonary veins, in llie vralls of tne aurielea. 
in lh« auric-ulo-veiilrieular Kr<WTe, and in the bnaal portion of the vonlriclet; 
further. aLxnrdiui; to wme obserTers, in L-ontrast m the fru;;'^ hearl, u num- 
bor of *mall ^itn^lia may be observed over a \^rge part of the veiiindc fur 
4oim luKurd ih(- ajH-x. Tbo auricular ^ptum, nl lea^i in iu cunlrul partt. 
id fnv fruni jjaiiulia. The nerv«« and gauglia lt« for lh« most part superli- 
ciailj imnuiliatiny undvr the pi-ricardimn. 

!■ i1h> frog th* libmi furmiii^ the vagUK nvrves an lb«y nin alone ihe 
•Mfrior TriUi cSTiv nrr (-ompDwd of uiid n(in-m«dullntcd finm, 
tht lut«T tmng chifflr. if nm. uhollv, di-rivcd iV'im tho iiilanchnic or lym- 

CktiMic ■yatrni. MMulUtwl Hbn-*. with ■ larger pnipirtion of non-iiiRduU 
I»tI ffbmt, an' f"unil in tlir g>'pliil ni^r^'w riinnlni; In BiddcrV gnniflia. but 
i1m> fin« fibtt-^ nhicli (mw from Itiddcr's ^iinKlia to llir «ub«lunoo of ihe tc«- 
l/ict« an- ficluMi-ely nuniiK-d'illeilod Son*. Thi- iicrvo cells Jn the siDtu 
(;■&«)*> and alou}; ih« c«ds of (lit- vagus ii«rv(«, us wHI ns some of the mIU 
cif iJh> ^ii;;ltu M:Hlter«H over the Kcpliim. nr« of the kind prariituiljr (§ 96} 
dorriheal as iipirul e«Itf. The coll$ compneing Bidder's Kunt^lia, at well M 
maoT nf the celU in the seplum. are said to be bipolar and ru^iiform. 

In the mnmmnl tli« fibret puasinK to the heart are al«o meilullated und 
afNi-Rir>lulIatr<l. Some uf tlic raedoUnted flbrM are nf Hne calibre, muy Ite 
tracnl back to thi^ vniciu. ami up|H.-ar to be Rhn^ of wliich vrc *liull (penk 
nrcMinilr a* inhibitory. (Ilher* of the uiC'diil]nle<l fibres urv of larger call* 
on. aiM sum* of tlxvK at ull events upiieur to be aeiuory, or at ti-aal allcnut 
in ftiBCtloti. Of till- uon-mealullulvd libres, itome may be lnui->l luck aloiig 
the ccnlUc ai'rvr* |o ihr infmnr rvrvicul gnnzlion, und nri' of thv kind we 
»li«ll speak of us augnM-nling. In cmtnut to Uie frig, many uf thr tibr<« in 
th* voairicta (wlicro thev lie rtufi' itndt-r the pericardium) are mmlullatcd. 
■ad it b probable thai tbrsi- art- uflVrenl Hbrvf^ 

Tb« eMf (nrmiuji the rnrioii* ganglia XTUltCTed over tbo miimmnlian heart 
■nr. pertu4«. h^ elasMd af unipoliir und multipolar, the fi>rmvr being ape- 
ctally mnn«oie<l with medulUted libres, the one cImm being praniincnl in one 
•bawon. the other in nuolli«r. 

TAf liewlnfitneitt of the Ntrrmat Rfit. 

Tba heart of u miinirnal or of a warm bliwitlvil anininl gvnemlly 
U> h«M within a fen minutin uftor bviii/ rvmured from tb« bwly in 
tbr iinlinnry way, the liisirt* of nnwiy-born animilii uoniinuing, liowcvvr, to 
tvBi for a tongvr tittiv ihaii thiMp of adult«. Hunee, though by spcoial pro- 
caationa and by mcam of an arltlicial circulation of blood, an Nolatvd 
nuimmaliun lionrt wny lit* prnfcrvi'd in a puUatin^ coudittoo for a niui*h 
Inoyrf linw; our Itnunli-il^i- of lb" exarl naturv and of the cniMU of tbo 
«anl(ac l>«at i* ai yel vry largoly bavod oti the study of tliv hearts of ixild- 
htwtA^ animals, wliich will conltQiio tu bral tot hours, or undc^r fnvorablo 
<iiTt*iiaM(anoM enit for d»y«. aAer they havr been remiive<l fMm the body 



witti only ordinary care. We have r*iisou to think that Uic meclianixru by 
which the bent i« c-arHcd ou varies in some of its Becuodary featurvs ia clifTer- 
em kinds of animala ; that ihe hearts, for insuin^e, of llie eel, the snake. lh« 
tortoiwi, and the frog, difTer iti some minor details of hehavior, boili finin 
Mch othrr mid I'roni the hiril and the luaintiial ; but we may, at Gr«t at all 
evenlH, tiikc lh<> hmrt uf the fmg iis illutttnitiuK the nmiii and iinportsni 
truths coiiocruiiig ihi; cuiiim and incchanisin of the beat. 

In HiucIyiiigclMely the phoiiomeiia of tliel>i-iit vt iLe Iienrt il becoiives nect«nry 
to oliiaiti a grajihic recurd u( vurtoiia movrmnils. 

I, [ii tlic (tQg or Dllirr coldlilomlcil nnimnl ■ lii()it IrTOf may be plMvd dirirctif 
on the vcntrtdc {<>r on an iiuricli'. rlo.), iind ohurisn of totm. due eiUit-r to dislMI- 
lioo by th« influx of blood or to ihe ivmole. will tuu»e luovi-mcnts of Ihe levw, 
wbicli may bo recorded on a travelling tiirfncc. The «ame mtlhods, an we bavt 
•een, may be applied lu tlie nininmnlinn hciirt. 

3. Or. nil in C.iiukcll'« mrthod. the bntit may be fixeil by n clamp rarerulty ad- 
jiiatfd araund the •uriciild-rcutricular Krimve. while ihe apex of tlie Tcotricle and 
aome portion of one aurii-le are attached liy ibrtiidH to liori/Antal levers placed 
respectively nbOTc and below the lieatt. The anricte nnd the ventricle each in iia 
sVKlolc piitlH nt the Irver attached lo it, and the limea and eitrnt of Ibe oonlrac- 
ttoni niny I bun be recorded. 

3. A record of «ndo-cardiac preaaure may be taken lu the frog or lorioise. as in 
the tuauimal, by nieanH of an appropriate manometer. And in tliose animals, at 
all CTcnls, it is cnsy to kec^p up sn iiTliReial circulation. A csnuU i* inimduvcd 
inin the oinna reooKUs luid nnothrr into the ventricle through llie nurtn. Seiuin 
or dilute blood (or noy other lluid which it may be denired ta employ) is driven 
by moderate pressure ibrough ihe former ; to the latter is attached a tub« con- 
nected by meaos of a side piece with a small mercury mnnometer. So long a* 
tlM exit-tabs is open at the end fluid flow* freely throu);h the hriut and appaimlua. 
Upon cloiiog Ihe exit-lube at its far end the force of the vcniricular systole is 
brtrashi to bear on tha muiomel4)r. ibe Index of which reaisien in tlie usual way 
the movements of the mercarv cotunin, Newell Msrttu hu* succeeded In apply- 
ing a moditlcation of this metliod to the mammalian lieiiri. 

4. The movcmenis of ihe ventricle may bo regipiicred by inirodueing into it 
IbrDUgh the auriculo-veniriculnr orifice n ■o-called "perfuiion'' ranuln, Figs. 91 

and 'Jn ]., with a double lube, one inside the other, and tying 
F^-91- ibe rentrlcle on to the esnula at the aurfculo-voBtriciilar 

ETOOve, or at any level bclon that which may b« desired. 
The blood or other fluid is driven nt nn udequate prennurc 
ihtuLieU the tube a, outers ibe vi-oiricle. und returns by ihc 
lube b. lib he cuniieeied with a niauometer ss lu method 3, 
the mnvemcnis of the ventricle niny be registered. 

&. In ihe appnmtnsof Itoy, Fig. 92, II., the exil-tabe is 
free, but the ventricle (the luime method mny be ndonlcd for 
Uie whole heart) is placed m an airtight chamber filled with 
oil, or partly uilh norniid saline si)1uii>>u and partly with oil 
By means of the Inhe A the interior of the chamber a is ooii- 
linuoiu with that of a tniiill cylinder e in which a pUloti */. 
■erured by a thin tlexibli' aniniul membninc works up ana 
down. The pislon sgain liesr^ una lever ebr mean* uf which 
its movement* may be rcgiatcrcd. When Ihe veulrlcte con- 
A PurnatDi C*K\i.^ Iraels, nnd by conlriicling dimlni*he* in rolunie, there is n 
letBCuing of presHure in the interior of ihe chamber; this is 
limitsmilied to the cylinder, nnd ihe pisioti correspondingly rises, carrying with it 
Ihe lever. Aa ihe veniricle suliMqiicntly becomes distended the pWMwre In ibe 
ekambrr is incicnsed, nnd the iii*i»n und lever (.ink. In this way varialiona In 
the volumu of the vrntrirlo mny lie reiorded, wilhuut noy great interference with 
Om flow of blood or tluid Uirou't'h it. 

The heart of the fro^. as we have just said, will rontiuue to beat for hourv 
afler removal from ihe body even alter the cavities have been cleared of 
blood, and, indeed, when they are almoet etupty of all fluid. The l>eais tlius 




cmirird out ■!« in all iiu|>»nant rM|iocts idcntiml with th« l»rA1»«x«:uir(] by 
th* bout in iu tiunn»l coattittoii wlthtu the living ludv. Hoooc vn- mity 
loftr that Ibr litul of tlic haul » ui Mitmnutic ■cti'iii ; ihc aiuHtiliir mti- 
t iaci ia w which coiigiitiil« lh« beat tre due to ctiiiM-s which arifc Rpunla- 
OMHMly in lh« Itmrt iueir. 

II rw, ta. I 

t MMiM mute tint IMn ItaCt rmtili'lc n, «ntrmn<p; b.«i](-lul«. < . wall oT notriclt: fi. 

KloTikpiMmlai mulUM br lluklll. a, (kuDlnr llUtd wtlll wIIik •iiliillun iiid nil. «cmlalii- 
llfc imiiWto * iMcntoforfUMoucaiiula/. ti,iBbe1iadIiittooTllui]i'rc.liiHUtiIiiiiuTaplMan 

tn th« frog'* honrt, u in Uiitt of tlic mnmnml. $ I'JO. ihrri' it> a dirtioel 
iwftiico of tnrniU which ia ihr miik- whi-ther tlw heart be removed from, or 
WniU io ill normal coodition withiti, the body. Fim cone* tlw beat of 
lit MDus Tcnoeiis, precr<lr<l by n titonr or !<■» jhcriBisliic «>ntnictton of the 
iirg» wins leading into it, next lbllon» tlw oharp beat of the two auricles 
VfHittt, then otrmea the longer benl of th<! ventricle, and lastly, lh« cycle ia 

■plated by tlie beat of the biilbus arlerioeus, which does not, lilte the 
Jiau norta, simply recoil by elualic refleli»n after diatentJOD by tb6 
_ 'Jcular Mrtike but canioa out n diHlinci muscular contrMtJoD pMeing io 
iwtve (htm the venlrii-tb outward. 

Wbon lb« ii«art in dyiti^ oeosee to beat, the oeveral niovenienta ceuK, aa a 
mle, in an order the inverw of ilic alMve. Omiltio]; ibe bulbus urteriosus, 
■ hkh aometimtit exhibits i^real rhyttiinioal power, we may say that first the 
Ttatriole faib. then the auricle* fuil, and htnly (he aiituti vtmasua ikila. 

The heart aAer it had c«aaed tu beat >ii>uniune«Mi»ly n-tuainit for aoow time 
iiritable — that i», rapubk-uf executinj; a beat, or a ihorl wTica of beata, vbeu 
■tinulaied cither mcchiiDi rally, a* by touching it wilh a blunt iiccdlv or dec- 
Itiially by an iixluciino xhuclc or in other wav«. Thu artilii'iid l>ont to called 
fcrib maT b« in Us muin feuturcn kli-iitical with the natural Ih.'AI, all the divi* 
■ioaii>r tlie ht-urt taking jiarl in ihp tii-jil.aitd ihom-iiucncxtol'evfni* bring tho 
an* a* in th« nntural beat. Thun when the (inu» in |>riokvd ihv beat of the 
MBM may be fdlluwnl by a Wal of [he auricle* and of tho vcntriclo; and 
trtn mhvo ifaa r«nlHcl« u Ntimu luted , lh« dircrlly following boat of tlie ven- 
liicl* may Iw MeOM<l«d by n i-omplrte Iwat of tti<> whole heart. 

UacWr nirtain circumstADOoa, how»v«r, tiM< divtAon directlv stimulaicd ia 


aUy the 


tbe onljr III10 tu Iwitt: n-hrn the v<Milride is pncked tbr iustaiic« it kIodb 
beatii, or uhcn thti tinug is pricked it nirtiio hcalK T)ie reeiilu ol' ittimiilBtioo 
moreover may iliR'cr iiceordin;; to lli« conditioD of ihe bean and accurding 
to tbe niirliutilur i|mt to which tbe etimulus is apfiliod. 

Wilt) nu incretising Iusb of irrilabilily, tbe response to atiaiiilatioD cmms 
ID the Kveml divisioDs in tlie sanie order as that of the failure of iIm natunil 
beat — tbe ventricle cea«« to respoiitl drat, tlieii tbe auriclai, and lasllv tbe 
uiiuB veoosufi, which frequently reepundtt to slimulatiou long allcr ibe < 
divuious have ceased to make any »ij;ii. 

It woiihl ap}>ear us if the s'mu.^ veiia«u«. euriclcii, and veiitriol« fbrmedS 
d(MC«ndin){ ^ri«« in rtf»i)>ecl Ui ihiiir irriliibrlily utid In rhr [inwor thrr P«m4 
of carrriii); oti MpiinianeiiUE rhythmic hcjil«, the »inii* being the matt pat«llf 
Thill i» aW ^len in tbe foll'uvrrig exjMrimoiitK : 

lo order that the frog's heart may hi--iil iiA-cr reinnval from the body with 
Uie nwircKt nppn>ach in rapidity, regultiritr, and cndurancfi to the normal 
c'ltidiiinii, the removal must l>e carrictl out so that the excited heart dill 
rotaiiiK the itntif vcnwiix inl.nrt. 

When the inciiion is corricd through the aiirides so as lo leavv lliv sinus 
venoeus behind in tbe body, the rvaiilt ie dilferoiit The iiuut vcnoeus beats 
forcibly and n?giilarly. having Fiiflered hanily any interruption fmm the 
operation. The excised heart, however, remains, in the majority of cases, 
for some time motionless. Stimulated by a prick «r an induction -sliock, it 
will give perhape one, two, or several beats, and then cornea lo r«et. lu tiie 
majority of cases, however, the animal having previously been in a rigorous 
condition, it will after a while recommence its »|K>ntaneoas beating, tlte systole 
of the ventricle following that of the auricles; but the rhylhni of Iwal will 
not bo the same aa that nf the sluiin veuosaa lefl in the body, but will be 
slower, and thi^ lieniv will not coiitiuiKi to go on for so long a tiRx- a» will 
those of a heart mill retaining the nnus venosiis. 

When the incision is carried through the aiiriculo-vtaitriculnr groove, so 
as to leave the auricles and sinus venosu? within the body, and to isolato ihs 
TCiulrlcle only, the renult^ are i^itnilnr but more umrkeil. Tbo sinus and 
auricles beal regularly and vigorously, with tlioir proper Mouence, but the 
ventricle, after a few rapid contraclionsdue to the incision acting as a stlinu- 
las, generally remains f<>r a lung time (|iiie^oent, W'h^u Mliniulaled. hoiv- 
vrer, the ventricle will give one. two, or several beatn, niiil after a while, in 
many ciM^^ at lea^t, will eventually set up a apootanenui puUation with an 
Indeiwndent rhythm : and this may Inst for some couMidcrable time, but tbe 
beats are not ito regular and will not go on for so long a time m will those 
of a ventricle to which the aurioiea are still attached. 

If a transverse incinion be curried through the ventricle at ahrmt Ita upper 
third, leaving t)io hone of the ventricle still attached to tbe auricle*, the [lor- 
tlon of (he heart Irft in tin- body will go on piil.-uttiug rojiularlv, with the 
ordinary setjuftncn of sinus, nurides, vuntricV, but tbo iHvlatw] lower two* 
tliirds of the ventricle will not heal spontanoously at all hnwover long it be 
U-tL Moreover, in rt:>)>on«: ^J a single stimuhts such as an induction shock 
or a Ktntle prick it gives, not as in the <-ni<c of the itntiru ventricle, when 
sUmulaled at the base or of the ventricle to which the auricles arc attached, 
a serica of beats, bat a simple l>eat. 

Lastlv. in complete the olory we may add that when the heart t> bisecteil 
longttuiiinally, each half continues to l>eat aponluneiKisIy, witli an indepen- 
dent rliythni. mi that the beats of the two halves are not iKCeaaarily -vM' 
chronouH, and this iMUiinuani'e of s|xinlaneo(tp pulsations after longituiHnal 
bieet'tlon may be SL-en in (lie conjoined auricles and ventricle, or in the iso- 
Intcd auricles, or in tbe isolated but entire venlriole. MureoN-er, the auricle 



imf he dividrd in many wan and yet luiny of lh<> »0|pii«iits will r<iiilinutf 
bsiing: unall i>\w^ er«n mmy W neen iindcr ibe niit.-ruBCO)>c |Milmiii);. 
fnUy. k B* tmv, but ilMinclly and rhvthmii-nlly. 

b thcM expenmenu, tl)«ti, ili« variouB pariB of ihi> fro^'n Iwart alw form. 
H rvnb tmt power of 8|>oiiianeouB iml^'atiou, a dncvnHins serin: siniM 
nSGN*, •uncles entire ventricle. lo«»r jwrlioDs of Ttrn(ncl«. Ilie )ut exhibit 
lif asdtr (irdinMr)- circumBtuicM no B|)i-iniaoeauB pulmlion^ at all. 

i IM. Mow we have seen <§ i53) tlint these parU form to ■ certain extent 
■ MDikr (kaoatMlinf; aeria m nyarJii ihe preaence ofjianKiia : ai leaHt bo for 
tki the nojtlii are verr numeroiiB it) ilw itinuH veoosus. that the)- occur in 
tW Mrieles, and that wliilc Itiddur'a f[0»)clia are preeuit at the junction of 
tW mMride with the aurM:l«^ ganglia are wholly absent from Ihe rest of 
iW natriele. Hence, on tho aMumplion (which we have already, g 100, 
iwg namm to doubt) thai (h<: nerve cflU of ganglia are aimilar id general 
AactiMU I0 Ihe nerve rclln of the ci-nlnil ncrroun «yMem, ihe view very nalu- 
aHj pnaata Etaelf that thr rhrthmic niHintani-ouH heat of the heiirl of the 
#•{ !• doe iQ iImi ■[HintaiMyHiii pMicrali^^n in the gaoglioDic nerve cells of 
rlnllmie imrfur impulMii which puvitii: down to the niiMCular Bbn« nf the 
Nnnt pana auMS rhythmic contnicti'<nB of (hrw (!bn-«. ihn M-i^urncc and 
aMioBtian »f the beating of the ■cvcriil diviiinn» of the hcnri lifin^ the 
mAtoft coiinlination Wtwcrn the scvcnil ganglia in n&gard K" ihe p-nera- 
l^if iBi|i<il«M. Under this view ihecsnliac muKciilar Itbre Dimply rrajiondt 
l<tbe aolor irii{>iil«ea nsacfiing it along ite motor nerve fibr« in the ■nmi- war 
» Um •kel'-inl maseiilnr fibre rmiMindi to the tnnlor iinpulsee rcnching it 
ilmg ila HNXor avrvt' tihrt- : in bolh caaee the museiilar nbrc is, as it wcrv, 
1 pMtve inntniRM-nl in the handf iif tbe molor nerve, or rather of the nervous 
nain- i ganglion or spinal cord ) from which ibe motor nerve proceeds. And 
ii» Tww. thus baaed on the fact >if ilic frog'ri heart, ba* benn extended to the 
kaitinf (vertebrate) aaiiuaL< generally. 
Tkrra ai* rvtwona. however, which shmr tlint this view ia not tenable. 
For laaiaae*, the lower two-thinl*. or tower ihini, or i-ven lh« mere tip of 
Or frps'a vcfltHolc — tluit ijt to mij. {Mrt* which are ni)mitl<-d not to onniain 
wr*e etll*. luity, hy R]iei'iiil nieiinn, l>e indiicol to carry on for a coiiiidorable 
ttBsa rhjcibmic beat, which in it* main fcHitir<» ■• iib-ntiral with ibe 'pM)- 
taaMoa baiat of the ventri<:lo of the intact hesirt. If mi-h a ]iiirl of iho fnig'a 
nntride be tied on to the end of a ]>erfii>ion canuU (Pig, 91 ). the portion 
•^ the ventrinilnr cavily Monging to the pari mnv he sdei)ualely disteiidei) 
Mil at ibo *»itii- time l>e " fed " with a suitable fluid. «iieh as blo'^i'), niude In 
'ibmugh the eaniila; il will then be found that the portion of ventriclo 
atcd will, nfler a prelim in iirr pi-rii>d of qiiieseeiice, C!>mmence to boat, 
Rally «[Htntaneniis]y. and will continue a-> beating for a long period of 
It mar be sui<l thai in this ease ibe di^lentinn of the cavitv anil the 
ily of hliKnl or other tlutd acts a* a aiiniuluB ; but if ao the stimulus is a 
'nuous one, or at least not a rhythmic one, and yet the beat u mnst rega- 
Then, apiin, lite reliictaiice of ibe ventricle to rxenile apontaneoii* rhytbmic 
1 1> til n certain rxteni |<oculiar to the fro;. Ttie ventricle of the tortoiiM), 
oManoe. the grenD-r pin of the MitMlancc of which in n* tree from nerva 
I a> U that »f the frit^. will heal iiiK)ninneogiily ithen iaolnttMl from iho 
I nilli grimt turn- ami for n limv' titni', Kiirther. n mere Htrip of tbi* 
ibr niUK'ti' ti»'.i'-. ifki-pi gi'iillv e^ttcnded and Cixitinunlly riioisteiiod 
I hhmd i>r other -iiiiabic llnid. Hill e inliniie In bmt njnnlanoutly with 
'irrral rv^ulnrity I'nr cvi'n 'tiiv»,i-«|v>eiiillv if tli^-MriCM bo started 
b pivliiiiinarr application of ind>i<iion-flio<-lif Hiythmtcally repMtwI. 
fn runnei-tiiKi with ihi* >pir*iifiii we mar call atlenliofl to the fact that the 



cntvlinc fUliiciilar fibru i* not wholly like the Hkclvtal lutttcular i 
inanj n^ped* iIkt niulriictimi iir lii-iil of the fornivr is in i1« very luilutc <til'- 
fcrcnt fivin itic coiilnictioii of thii lutlcr; ihc Hinncr canoot be coiisiderwi. 
like the laitcr, u mere in«(runu-nt in the hamis of lh« nolor nrrvc (ihtv. 
TIm^ IV-jiturc nf the bcitt or contrsclivn -f t^rdinc mitfcW mny be rtudieU o« 
th« isolated mill (luieccent vcnlriclfl. or part of llie ventricle of ihe frue. 
When HiK'h n ventrielo is stiniiilsteil by u eingli.- r<timulu«, such rs » HUgTc 
in dilution -shock or a single louoli willi a blunl ni'edle. a bent moy or may 
not result. If it follows it ivseiubles, in all its (■^iieral feature* »( leaM. a 
spontaneous beat. Ueiweeu the application of ilie stimulus atid ili»' firei 
appearance of any coptraction iu u very long latent period, varying aecordiDg 
to ctrouttistaDces, but in a viKiirous iVesh frog's ventricle bein^; abouC O.-i 
Mcond. The beat itself lastH a variable but vensideralrle time, rising «loKly 
to a ntaxiniuiu and declininx slonly aKain. Of course, when the bent is 
reconled by means of a light lever placed uti the ventricle, what the iradng 
altowfl is really the im-reai« io ihe froni-io-bKck diameter of the ventricle 
durJDfc Ihe beat — that in to say, uoo of the rciiilfn of thci eonlnic-tion of the 
inrdiae llhri'!' — and givM, la an indirect manner only, the cxt^t of the cuD- 
traction nf the filin-x thcmM-Ivt-n ; ami the Mime u the cniie with the oilier 
methods of rocorditig ihn mnveiD<:nli( of the whole venlnclc. Wr may,liow- 
cver, study in a more direct way ibe contrnclioii of a few fihrm by taking a 
slip of the ventricle (and for this purjioM the tortoise i» prefembh- ti> tlic 
frog) and siisiH^^ndiiig it to n lever after the fashion of n nnm-le- nerve |)re|<*- 
mtion. We then get a curve of eontraclion, chamcterixed by a long latent 
period, a slow long-conlioueil rise, and a slow long-continued fall— a con- 
tmclinn, in fact, mora like that of n plain muscular fibre than of n skcJetali 
muscular tibre. In the tortoise Ihe contraction is particularly long, tlte oon-' 
traction of even the skeletal muscles being long in thai animal ; it is InM 
long, but still lonu. in the f'tog ; sliorter still, but yet loug as compared niih 
ihe skeletal muscles, in the mammal. 

The heal of the ventricle, then, is a tingle but relatively slow, uiolon^ed' 
eonlraction wave Hwe«ping over the iieculiar cardiae muHcIe-c«li, paesiug 
through the cement suiutance from cell to cell idoug the Rbn, from Hbre to 
fibre along thi; bundle, and from bumlle t^i bundle over the laliyrinth of the 
ventricular walls. 

Like the e«se of the skeletal muscle, this Mngle contraction is accompanied 
by an electric chung<r. a current of action. The intact ventricle Si res* Is, a*, 
wo have nlrcjidy Mid ($ 65), iwK^leclric, but t«ch pari just as it is about la 
enter inUtastalo of eontriiclion iH-oomes negative toward the mt. Hean, 
when the electrode!- of a galvnniiMn-ler arc phiccd on two points, A. fi, of lb* 
•iirfaoo of tli<- ventrirle, a ilijiliiihiv variation of the galvanomcler needle i* 
seen just a>a U-ai, natural or about to occur, i^upposing llint the 
wave of eontraetion reache" A first, this will become negative toward the rest 
of the ventricle, including Jt, but when the wave some time afterward rmcfaei 
B, h will become negative toward iho rest of the ventricle, inclading A. 
Compare § fJT. 

The beat of the auricles, thai of the sinus venosus, and that of the bulbui 
Uieriosus are similar in ibeir main features to ihul of the ventriule, so that 
the whole beat may be consi<lered In be a wave of contraction sweeping 
Uirough the heart from sinus to bulbus; but Ihe arrangement of fibre» til 
nich that this beat u cut up into sections in such a way thai the sinus, Iha 
auricles, the ventricle, and the bulbus have each a beat, so to speak, to them- 
•elves. In a normal state of things these n'verul uart* of the whole beat 
follow each other in the secjuciice we have deM-ribtsl, hui under abnormal 
oonditiona the seijueuce nuiy hi: revcnted, or oue rcclion may beat while tb< 



or Um scverml wclioiM nwv bcuL out of lime itilb vach 

fe fiir, tko dmcHpiino nf 
tat iliirm fmtn llial of a «k« 


th« c^nlrncliou which ia lli« fouoHfttioD of tlw 
k«Ietal luiitcle in de)>ree only; but now oMnw an 
b^rtuil iliflereDM. WIteii we tttiiuiitate a skeletal muscle with » strung 
Miuhia we fiei it \trg^ cnnimction ; trbcii we apply h o'eitk itliniulus wc gti 
■ *>ll coDtraniiiti ; uitliiii certain limits (we ^ 7'J) the contniclion is pro- 
ptiiunal to i)ie •limuhiB. Tliis isi doi thi^ chso wiili the quiescent ventricle 
It bran. Wheu we npply a »tnuig imluction-ahiick wo get a beul of a our- 
ma Mjwagih ; if we now upply a wcitk ubitck. no ^i either no lieni at all or 
q«W U •tnMtjt > beat na with the glroDgiT riiiiiuluv. That la lu say. tho 
■uniltidv of tbe In'nt <Ie[ieDd« on lli« conitiiinn nf thi:! ri-iiiricl« 'or liearl), 
aitot na the magniluile of U)c itliniuliis. If Ihf miinuliis t:uii viir the veit- 
tridf i>p to l>eiil at all, llut brat i* ihr Ihi>I which the ventricle lU the time 
aa utitniplith; the ttimiilu* either proclucc* it« maximum cfTcct or iinoe at 
tIL U would weni m if the stimulus dow iiot pmOuco a oonimctiou in ihe 
«nir war that It doea when it is hmugbt to bciir od a skdutal niuoule, but 
athrt *ti» up tbc be«n in Huch a way os to enikble it to execute a spon- 
tumuthnt, which, without Ihe extra slirotilus, it couM not briog aboiiL 
Aid this » further illustmtcd by the fact that when a rcntrtdo is beuling 
rbnimiatlly. eitlier ■pMitaneously or as the result of rhythmic «titDuluti<>n, 
ihrkind of sObcl produced by a now etimuhis thrown in will dojieuil upon 
ihianet phnae of the cycle of the bent at which it is thrown in. If it b 
ttnnt in just m a relaxation is taking place, a l>eiit fullows pram a lii rely, 
Kdar* the next btnt would naturally follow, this premature beat being obvi- 
miy produced by the siimuliis. Itut if it be thrown in just as a contraction 
i> biglflniiig, no premalure bt-al followH; the ventricle <toe£ not seem to feel 
til itimulus at nil. Tht-rt.' L-> a jxnuil •litriii}; which the ventricle is insen- 
■iUsloBtiinnIi, and that hnwrvi-r itnmg; ihio jKrioi] ii> cjillcrd tlie"reA«0- 
period. (There in, it mny Im mentiuiml, a similar ratVactory period 
muscle, but it is of cxceeilirigly short diimli[>n.) From this it 
lliHt, when a succowion of stimuli repeated nt n certain rate are sent 
llie ventricle, tbc number of beats doca not corrcs|iond to the number of 
ttinuli : H>mc of the •limuli foiling in ri-fractory periods are ioeflcciive and 
— Wc« no heal. Hence, also, it is iliflicult if not impotsible to produce a 
tetanua of the ventricle, to fiieo n iiuinber of beats into one. And tlier« 
■Olhtt faclf tending to show that the contraction of a cardiac muscular 
ffven when induced hy nrtilicial stimulation, is of a peculiar nature, 
hat the analogy with the contraction of a skeletal muscular libre, in- 
by motor im|HilM« reaching it along its nerve, does nut bold gotMl. 

and other conf^ideratioiig, taken together with the facts already nien- 
', that portions of cardiac mitbcular (istue in which guiigHoiiic celh> are 
tfttaialy not prcseni. can in vari'ios animals be indiicni. either eawly or 
•ttli iliraralty, to execute rhythmic boats w hich have all the appearance of 
bsiag Hioalaneoiis in nature, leiul uh to conclude that tbe beat uf the heart 
BMI ibr mull of rhrthniic impultea pmceediu^ fruu) tbe cells of thi.- ganglia 
lS|aMitc muscular tibrE«. but i^ mainly tbe result uf cluuiges taking; pUc* 
fa tfca moKuIar tisane itself. Ami here we inay cnll attention to tlie |>eculiar 
Uulos^fal features of cardiac uiutcular tjisue ; ih^Migb so far diflerenliatad 
I* In be striated, its cellular ooostluition and its " pnuopluMuie " features, 
iKluHiu)^ the obfcuritr of the striation. Dhow tliat tbc diirereiitiation ia iucom- 
pbte. Sow, ooe attribute of uuilifrrreniinti'd prioionlial protoplasm is the 
puerr nf •[■ontaoeouH tnovciueni. 

t U6. We have, moreover, evidence that it '» the ninsctilar tissue, and not 
■W amngeuent of ganglia and nerves, which is primarily concerned iu 





ntniniaininj; the remarkable neqtience of sluii^ heal, aurictc beat, uti<t tea- 
trick- Ileal, ThU h jwrhaps l)yiter seen in ihe bean 'iT che lortwise than in 
that of the fru)>. 

In tliia animal llie iiervea paniiiK IVom tbe sinua to tbe reatricle maj be 
divided, or ibe several a*")?!'^ nm}' be re*(H!etiveIy removed, and ret the 
normal ee<|ueiii'e i^ maitiiuiiteil. On the other linni), we Dnd that inieriereitce 
with tiie museulnr xib^tiinoe of th« niirii-le, whea rnrrit-d to ii otrtaiu ext«Dl. 
prevents the bf ul ol' ih« uuricK^ pn-ttiiig <ivvr lo ilif veutricic, hu that th<:*cqi)ence 
IS broken adur ihc niiricle beat. If, for inxLanw, the aiiriclt' he cut ihrnusb 
until oiily n narrow bridge i>f iiniticl^ be Irft (.itiincL'tin^ the part of the 
■nricle adjoining ihv siniif with the [Mrt luljmiiinjc the aiiriculo-vcniriculu' 
ring, or if lhi« purl Im- C'iniprc»*(^d with n clump, a Klutr of tbingit maj he 
brought abiiul in ii hifb fvrry sci-ond honi <inlv, or cvnrv third beat only, of 
the *1DU« nnd nnriclc is followoil by a bi'iit of tfic vinitride : and then, if th« 
bridge bo still further nurrowed or the L-Iiimp screwed tiehl<ir. ihi* vcniricle 
doc* not nl all follow in ils bent tbe 'eqiiorice of ainiii Hiiit luirii-tc. thmigh it 
may nftpr a while eet up an indeimndrnL rhythm of il» own. This ex|H>ri> 
meiit I'liggwJ*. nnd other facw flnp|>nrt, the view ibnt lh« normnl »ei]"cnoe it 
mainlninrd ni^ follovvH ; The beat begins in the sinuf (incliidin)* the uuds of 
thi> veins) ; thv coniraction wave, bet;iniiing at the ends of the vein». travels 
over the muscular tissue of the sitina, and reaching tbe auricle starts a cun- 
trnction in that iiegment of tbe heart : similarly the coniraetion wave of che 
Biiriculnr beat reaching the ventricle «tarU a ventricular beat, which in luni 
in tike fashion ciana tbe beat of tbe bulbu». And in hearta in a certain con- 
diliou it is pos^ble hy stimuluiioii to reverse thin sequenee, or lo produce, by 
alternate stimulation. lui ulieruiition nf a normal and a reversed aeqaeDoa; 
thus in the heart ofihe «kate, in a ocriain conditiou, meohanioal slimiilatioD 
of llie bulbus bv iiidiaiting a brni of the bulbu« wilUtarl a sequenw of tb* 
bulkiiH, TvnlHcle, nnrielc, and Riuiin. nnd similar ■liniulntion '^f the ainnf wilt 
produce n normal fiequ^iipa of sinus, ntiricle. vcnlricli>, tind Imlbu*. 

It nould. pitrh»|)s, be prt-mntiirc to iiisjfl that the m-rvous vlenieiita do not 
Intprrune in any way i" the mninlunanuc of thi" si.«|u<'ncc : but the evidence 
•howv tliat they iirr not ihi? main fnctof, nnd we have at prcwuC no snliifue- 
tory iDdicntioiis .)f ihe way in which they d" or iniiy int«rronc, » 

Two iiuestion* iialurnlly Bugp?Bts theniseK'ee here. The lint is. Why d'»ea 
the cardiac cvcle begin with the sinus beat? \Vc have pi\!vii>iislv, ^ l->4, 
given llie evidence ihnt the sinus has a greater poteiiliality of beating than 
the other parts ; iu nnd by itself it heals more reiidily and with a quicker 
rhythm than the other parls. When wc ask the further question. Why baa it 
this greater imlentialiiy ? the only answer we can at pivaeut give is that it u 
inburu in the subttance of the (inns. The problem is somewhat of the same 
kind OB why the heart of one animal hoaia so much quicker than that of 
amitber. All we can say at pn^eiit i* thai the rale is the outcome of the 
molecular constitution of liwuv, without Wing able lo detine that uiul«culAr 

Till' soonnd •(itration i*. Why doM not the cnntrncliou wave starting at tbe 
ninua spreiul m a coiitinuonit wave over thfl whole heart? why i» it broken 
lip into j«iuuK Ix-al, aiiricio ImuiI. venlriok be*l? We may here mil In ndnd 
the fact inenliom-'l iii S IM of tb^i existence, mon- or U««i mnrki.'d in all 
hearta and well m^-u in the hciirl of tbe lorlniae. of a niu.<rular rine or collar 
between tbe muii* ami the auricle, ami ()f n ximilar ring hrtwecn Ine auricle 
and v**nlrif|e. The muscular tiwue in lbt»e ring* swim* to he of a wmenlial 
diHvn-tit nature from ihe muHodar timue fortniiig the body of the sinus, or 
of the nuricle. or of the ventricle. If wp suppnec that this timue has a low 
t-o lid II cling power, it may oflVr oudicienl rwialaiice to the progren of the 




The (Jiivemmait of the tfetxrt-btat bi/ the Nervou* SgiUm, 

ctAiruttun lo prrtoit lite «iDU» ruri'SHmple lo cum out or to be far on ia 
llw dr% rln|)i»«iit "t'ila hcul, bpfuretbe auricle be^iDs \u beat (uiil thus bitect, 
•o tu tpmli. tb« Ileal wbich otJi«rwiee would bo ooinmon to the two), atid yet 
Dot nflcr ao much nftiatance na to jirovpot the cmintction nave iMw&iDj; ulli- 
■Mlalr (A from ihi' linua to ihc auricle. We may ia the tortoise bv carelul 
dUDptiie or Kctton of the auricle in ila middle, by which an obstude to the 
fantractiou wave ia introiluccd, bisect the eiiicto auricular beat into luo Ifeiitn, 
OOB or the |i*n between the ftinuti and the oluttacle, aod another heluecii the 
afa»Ca«:Ie and the wotricular. We may thus coniuder the breakiujc up the 
priroitivv uubrukeit periualic wave of o-iUraciiou from »i>ius li> bulTiuit fi he 
du« lo the iti trod uc lion uf Iwtue ul' louer (.-ouductiuf; jiuwcr at thi; Junction* 
mt Hm Mveral pana. 

We dn tux My liiat tbii ia the coiuplcte Mlution of the nroblem, but it Vt, 

Ht oflkn an apiwnxlmate aolutioo ; aod hen^ u.h olaewlicra we haw no 
Mtilfiwtary vvinlence of nervou* elenient l>eiu)c luaiu facLore in thv matti.*.r. 

la the above wc have dealt chietly with th« heart of the cold-blooded 
Miinal. but at far na wu know the tame ouiicJuHoiis hold good for the 
aMmnaltiui lieart alto. 

Tbe c|u«(iioti iiow arise*. If the jpuiglin are not the prime caote of the 
bctftn'a rbrlhmie t>eat. or of the niainleDance of the normal ee<)ueuce. what 
parpow cfo iher terve? Rut licforc weevvn itt(cn]{it lo nnxwer this iiucfllion 
m* Mint <]c«l wilb the nervou( mcchnnitms by which the Ih-hI of the heart, 
tfaoa sriaiDK aponlaneously within the tintjrs of the heart itself, \% modiSed 
umI re^latetl to meet the rc(|iiircnK'iit8 of the r««t of the body. 

^% 197. Il will becooTCnient lo be^in with the hcnri of the fruj;. which u« 
> have teca v conotcted with lite ecnirat nervoui* sytteni through aiid 
llwnrfbfa govenied by the two va|^ nervits. each of which though afipareotly 
a liBSle nerve rontaint, ae we »hflll tee, fibree of <liHcrciit oriein aii<i natarc. 
If while the beal# of th^i heart of a frog are being carefully rogi»tere<l an 
ialcrtu|Aeil uurrenl of ntoderutc strength be sent through one of the vaui. 
lb* twa/t ii teen to stop beating. It rcniiuns for a lime in diastole, perfectly 
■liliiiillrii umI iJacc-id ; all the niUKrulnr libree of the MVeral cbaniberft are 
fgr tba time lii'iug in a Hate of relaicution. The heart has been inhililni 
Int Umi impuleea devceodiug dowu the vagus from tbe jMut of tike nrnrv 

If ihK duralioti of the stimulation be shurt and the mietigth of the current 

t, \\»« •taiiddill may c^itiiinue alter the current hat lieeu abut ofl'; the 

it* abni they r<-ap|Mwr arv generally at fir^t feeble and iafretiueiit, but 

reach or even i,"' Iwyond their previouit vigor and frei^uency. If tbe 

dnratioB of tlie current l>v vtiry h'og, the heart may recuninu-nce heating 

vUklhe rtimolntion i* Mill going on, but the lHat>nre leeblcand iiitWguent 

ittMigb sradually increating in Ktrength and frcijuvncy. The vircrl of tbe 

Mtnolatloa ia at its maximum at or tnou aftrr the rommeuceuicnt of the 

spftlicBlioii of the stimulus, grudunlty di.-('lining afterward ; but even at the 

(M uf ft Very stimulation the beala luay Mill be tew in fiircv or in 

ftVfatBCY, or in loth, than they wen before tli« oerra whs stimulated, and 

"■ the removal of the current may show etgna of recover}- by an iiK-reasw iu 

toKe and fm|iteney. Tbe cfloct is not produced instantiuieoii!<Iy ; if on tbe 

emve the pciiiit be exactly markeil when the current ia thrown in, as al on 

Flit. S'L, It will fre<|ueDtlr be found that one beat at least occurs afler the 

timvni ha* pMr!«d into l^c Dert'e ; tl»e developmeot of that beat has taken 


place before itie ia)|>ulM« (ItMeiidiii)^ iIh- vngiis hsvo b>H time to ii^ct tbe 

The slitimlua ne«<) i»i>l nciMMMtrilr \>r tho interrupted curreul ; median icu I, 
ctieniieal, itr (hernial mimiilutKin ot iho vagus will also produce inhil>ilinn ; 
bill ill order lu ^'t a iitnrki-il ett'erl it it lUwmble tn make use ut not a singU 
iiervouainiuulte bulascriM«rDervoiiB irapulseB; tlius it iadillieult toobUiin 
any recognizable remit bjr employ ios ■ Nnf;le iiidu<-iii)tt-^b»ck «f niudoraie 
inteitnt^ only. A* we shall eve later on "natural" uerrous impulses 
docendiiig the viigun from the central nervous system, and staru-d there, 
by aHerent iinpuls<v or otherwise, us jxris of a reflex net, may produce 



■IB nwrlulliaUiiuM wlikb lli«tlRi«TTupial curnni «•• iliniuBlBioiIianRuat qf wlwnii nit 
•liut off. Tlir UtDP-nurkar tvl'>« msikii Mniinili Thi' Uwtt w«iv r^l^•*tn•l by nnpcndlBS Uw 
ventricle rroBBClampUIMtivl to lticnurteinilalU(TlilD(a lIcHI leTor lo Ilu^Up e< Uw VdiONte. 

Tlie stimulus may be applied )to any part of the< courm of the vagus from 
high up iu the ueck right down to the sinus; indeed, very marked r«Bull9 are 
oIitAiiiml by applyinc the electrodes directly to the sinus where as we have 
M«n the two nerves plunge into the substance of the heart. The Biiinulim 
ninr aluo he applied to either vagus, though tn the frog, and some other oiii- 
iiinU, one vagua is aometJntes more powerful than the other. Thus, it not 
unfre(|ently hap|>cns tJial even strong stimulation of the vagus on one side 
praduoos no change of the rhythm, while even ntoderate stimulation of the 
ni^rvi' on the olhi^r side of the net;k brings the heart to a stand^ill at onoe. 

If duriiii: the inhibition the ventricle or otlter part of tht- hnirl Ix* ntimu- 
lated ilirc^ctly, fur inittanoe mt.vhauically by the prick of a needle, a Wat 
may fullon' ; that is to tny, the irapiil«ai dectoiuiding tli« vafcus, while inhibit- 
inc ihc spontaneous boat*, have not wholly abollthed the actual irritability 
uf the furdiac tiRHUc«. 

With u current of oven moderate inlemitv, Kuch a current for ini^tAnoe as 
wmild produce a marked totouus of a muai-V-iiurve preparation. I he stand- 
still i; complete, that is to say, a certain numlwr of beats are entirely 
droppeil; but with a weak current the inhibiciitn i« partial only, the Iteart 
doe* not stand absolutely still but the beats arc slowed, the intervals between 
tlieni being prolonged, or weakened only without much blowing, or hnth 
slowed and weakened. Sometimes the slowing and sonietimM the weakening 
is tbo more conspicuous result. 

It Kinietimes happens that, when in the frog the vagus is stimulated io the 
nedt. tlie eflbct is very diOerent from that junt deacriiMd; for the beats are 
iaoiMied in frequency, though they may be at 6ret diminished in force. 
And, oocAiHonaily, the beats are increased both in fon^ nud in frequency ; 




iW rvNiU b BuicnwatatioD, not iuhibttton. Bui this !■ due tn tho fnci thnt 
a Uw ftw the va^^ alone the i^reater {wrt of iu nnirae is a tuu«d tierve 
■■4 onaiMiM flbm uther tbnn ibone of the vhrva jtja\>t^r. 

\ 1S& ir we eKHiiiiiii; lli« \amit uvrve cIml-Iv. Irnciiic it up tu tlte bntiii, 
*m finil ihni jiul as ihc nrrvi- biu iijvn.'ti) (he crsniiim, jiidl where it paasM 
IkfDVfti ibe gmngliuii ( (i. i'. Pig. Vi), oertalu fibn« puM into it Ctom iba 

1^. M. 

ftMMUitM' RamauuiitrKm n» ra* Ooomm o# CicutclAcianrrDB rtiaci ui ths Fm*. 

rAtmutir t^» lud tiiftiMm. I?. I'. gmgUiMi itf wt. O. Uii« oT onnliU nil. 1^. ncni 

VMt. 11. uBiUi. tli^tdi*t)»»i w l nwTg. A.rc wpntor mutjMnt. % ijaiikibatlc iMrm In 

■■fe. « r. |«MrtUii a< iTinpalhFlIc 0tn/I1iiii with rttmt ttntfifa HDdlOf l.r. lutn cnni*) nliiw 

t Mt C— !«■ gingUna Tbn mi -if ilw fmm ftlaiiir thB(TacTi> mink O' aptitiif biile 

I wlllt lb* Sn> (ptiwl iiwvv- </>ai>UnahBlrsia«ll(aior UiaMQODi] iiiiiial imrc 
>K r OToalw i>r ViMaanft Xi^ ■utoli«lin>(i«iT. iT"' itiUnoliaic fuifUaanf iliu ibinl tiiiiutl 
■••<• iit. IhIM •«<imI a*n«. r c. nmiu (.■miiiiiviiluiin. 

Til ■■III lit lh>a'i(inMili>cnhn«l« ■tbmu l>f IIif llilak tiluk llriv. rtaer m*y bv (laovl tlvin 
••«■•) «MdtTlb«aalalMi nwlof thcUilnl ipliul Mrn^thiousli iba mnu* maunu&lcaiB lii Uw 
•w^imIIw ff4M*ito vwalloii 0<" aiHa Uhbm l>r tta •Mond laoallaa O" tba •snulnc trf VIm»> 
■«Mi Hw Rnt mKMiHi 47 (# ift« iwilntl irmpalbiUc .%*nd n by Ibe n^ Uunlr to iln wfvilor 

*TBpalbaiic D«m) uf lite Douk, S3, of llie rurlhar ioufineotioiia of wbiob w« 
tlwltpcak pfOHotly. 

Ttm }k'm$ tba fluc^ w« uay expect that we abuuld set infTerfut nwilta 
MMnUi^{H w«atiiniilatetH')il>fl vaj^m io the craniuiD befur« it wan )oiiii>d 



by lli« ayiuputbeiic. i^2] tbe lympathetio fibres before tb&yjoln the voiiud. 
>»il I .i) tho va^iifl trunk coulaioiiifc the ronl vn^uB and Ui« BjnifMitbelic fibre* 
adtlud. Wbai we have previousl,r dwcribed are tlio ordinary resiili* of 
aiiinutBliuK tbe mixed iruuk, and Uieae, an we bave said, are uottibolty 
ooiiMiuit, utuugh UHually and in tb« maiu moHl distinct inlubitun' nsulu 
fulton . 

If wc Hiimidnle Ihe aym|iatbvti(r in llic neck, us at Si/, Fig. 93, cutting tbe 
nervv bolun, >»> us U> bluck all inijmlses I'roiu pajiiinjj dowunanl. aiid uuly 
klluw inipulieit to iitm u|i Id ibi- vuguti nod tb«DC« down tbe mixed vagu* 
trunk U) tbe beurt, vr<- gi't very reninrkuble reiulla. The beat of tbe heart, 
iiwtcad at being inliibiicil, \i aiigmcuted ; iIr- bcutt* are increaaed either in 
frequency or iu fnrec, ur most f^eiicrally both in fr«<jUGiicy and in form. 
Tbe 9tbcl it), [wrliap*. Wnt Men when the heart hvfure nlimulation i« Ifeatiug 
elowly ami fiwbly ; uixm stimiilalion of ihe ttrvic*! »yDi]iathetic tbe b«at# 
at onct imjirovc in vigor and frcaiiwicv ; indci-d, a fiwirt which, for on« 
ntflwiu or Biiothf<r, has almnst ccaeet) to beat may, by profivr vlimuintion <tf 
the symjiatbtrtic, be cnlk'd back into vigorous activity. 

If, on the other hand, wvAliinulalc iTic vngus before it bae been joined by 
the sympathetic tibrcH (and to insure the result not being raairad by any 
escape of tbe etimiiluling curreni on U} the sympathetic fibres* it if noresmry 
to atinmlate (he va^'us within the cranium), we get pure and cooslnnt inhibi- 
tory resultii, the boats arc for a lime wholl}' abulisned, or are slowed, or ar« 
weakened, or are both slowed and weakened. 

Obviously, then, the heart of the frog is supplied through the vagus by 
two seta of fibres coming from the cenlrHl nervous eyatem. the one by the 
vagus proper and tlie othyr by the cervical sympaibelic nerve, and these two 
seta liave opposite and ftntugoiiisiic etlecta ujiun the heart. We find ujxin 
examiuatiiiu ibat w« can make the follotviug utaiemenla coucerning them : 

Tile one i>et, (bow belonging to the vagun pr()|ier, are inhibitory ; they 
wcjikcn Iht' iiy»t<ilc and prolong the iliaelolc. the <-IIi.'ct with a strong stimula- 
liuii bring comjilcte. so that the Iicnrt is for a lime bnmght to a atandstill. 
Hometiinoi the slovring, eomotimes the weakening is the more prumincriiU 
When the nerve and the heart arc in good condition it needs only a slight 
stimulus, n wenk ciiirvnt, lo produce a marked effect ; and it may l>e meii- 
tioned tbnt the more vigorous the heart, the more rapidly it in beating, tlie 
easier i* it to briii]; about inhibition. Alth^nigh. us we have said, the effect 
is at its niaiiiuiim a»on after the beginning of stimulation, a very prolonged 
inhibition may be j>rodueed by prolonged stimulation : indeed, by rhythmi- 
cal stiniulaiion of the vagua tbe heart may be kept perfectly quiescent for a 
very louj{ time and yet beat vigorously u|n>u the cca&ation of tbe sUmalus. In 
otiier wurdH, the mechanism «f inhihitiou^lhat is, the fibres of the vagua 
and the |iart or tiulHitauce of the heart u[ion which these act to produce infaibt- 
tion, whati-ver that jiart or Aiibstanee may lie — are not readily exliauaicd. 
Further, the inhibition whi-ii it cauva in, Vre'iiiently at all evenly, followed 
by a period of rencli»n, (luring which the heari for a while beats more vig- 
orwisly and rapidly than bcror*'. lnd<:cd, the total eftect of stimulating tbe 
vagus fihrvs is not (o ex hau:<l the hnart, but rather to strengthen it ; and by 
repealed inhibitions cnrvtiilly adminialervd, a fcubly )>vatiug hcajt may M 
nursv<l into vigi>raus activity. 

The other set, tb<Mc joining tbe vagus from tbe synipnthctic, are " aug- 
mentor" or "accelerating" fibres: tbe latter name is the more common, but 
Ihe fbnner is more aecumte, since the effect of stinnihiting these fibres is to 
increase not only (he rapidity but the force of the beat; not only b tlie 
diastole shortened, but the systole is strengtbeoed, sometimes the one reauli 
and sonMtimes tlie other being tin nor« prominent. In contrast with ttie 



I of the ragu* fibre*, ■ numcnhiitalroOKitiiTiiiliilioii J* rt<iuim3 to nrcMliice 
»a effett : ih*- lini« retjuirvd fur tltc mnxTniuiD eHucL to lie pnxlucira w also 
tvmarkatiU lun^. Moreover, Ht all event*, tn ilie cuM of a heart in vhkh 
tb« ctrrulntttui i# not mnintaiiK^), nnd wliich i» therefore cut olf from it» 
ounumi nulrilivc diipply, tlir MUciTM'nior tibrv* nr>' far !««■ etinilv ■■xhnii«ted 
tiuui arr th<* inhibitory Abnt. tinnv. when in fiich H heart ooih Uti of 
fibnw are Miniulatcd together, a* when ihv vngiin trunk in the Deck m ttlma- 
Ut«tl, Ow 6nt rfle«ls prochiccd nrc thiwe of iRhihitJon ; bill tbiwv on cxm- 
linuetl ttiroalatioti mar become miicil with ibiMe uf auffmcntiilioii. nnd 
fioallv the latter alon« remain. Lottly. the contmst it oompletml by iho 
fart thai the auf;menlAlion re»iiltii)j; from the slimutaMon of the ermpathetic 

■ m fella«ed bv » period of reaction in vbich the beats are feebler ; in other 
wwda. aiigioeotatiun n followed by exliaustion; aiu), iDileied, hr repeated 
atimalation of ibcM rrnpntlielic fibres a fairly vif>DrouB bloodleaF ^ean may 
bv reiluoed to a venr ieeble coiiditiou. 

By waiching the eifecU uf atirotilMing the sympatbetic uerve at various 
poiata uf iu coune we may trace thew nugmeDtor fibrw from their junction 
wilk Ibe Tsgiu dowu the abort aympalbetic of the ueek ilimujib ilie first 

■ apjanchnic or aympathctic ganglion connected with the fint «ninal nerve IV' 
< rig. 94 >, through one or both the loofw of ihe iinnulua of Vieunieii*. .4m. V, 
duoagb the Mcood ganglion cw)niii>cted with tlie i^cond npinnl nerve. &", 
to tk* ibinl gM^lloa cooiMctvl with third »pinal itcrve. fw'", and theuoe 
thraagk Ibe nuniia nMomiinican* or viM^'ml branch of that ganglion, r.c, 
to lb* tblrd apjiud nerre. III, by the anterior mni i>f which itiey reach the 
apioB l oora. 

I IW. Both aeti of Bbrc* may then Ixi traced to the oentml nervous ays- 
nm : ud we find aoconlingly ihul the hfArl may be inhibited or augmented 
Wdcttoim inpuUee, which are Marled in the nervous aystem either by 
mMmvot tmpulaes as part of a reflex act or otherwise, and which paaa to the 
basft by the inhibitory or by the augmenting tract. 
Tbo*. if the medulla oblonjjata. or a particular part of the medulla oblon- 

C, wbicfa ia apecially connected with the vagus nerve, Iw «timulaicd, the 
t i> iiibibiied : if, for iiiMance, a needle be tnrutt into this part, the h««rt 
ataocU aiill. Tliia region in qutMion may be stirred intoaitiun in n " rt-tirs " 
■MUMrbvaflcreni impulses reaching it mim various pnria of the boily. Thus, 
tf tWabJoiDenof a fri>gl>e laid bare, nnd t!i« intetitine Iteslnick nharplywith 
lb* hftodlv of a tcwljnl. the lituirt will Miuid Mill in dianlolc with all the phe- 
B WnW Mi iif vafcus iohibiliun. If the ncrvi metenUriei, or the connections of 
tbM* nerves with the spinal ooni, tie stimulated with the interrupted ciirrvnt, 
euttiao inhibition is similarlr prodm-cd. Tf in these two experiments both 
f«gi an> (livi<led, or the tncoullR obh'ngatn i* dwlroyol. inhibition is not 
{wmhohI. however much either the inlcHtine or the mesctiteric nerves be 
rinBulaled. This shnws that (he phcnomeim arc caiuwl In* impiiUes asc«nd- 
tiif along the mesenteric nerve* to the inealulln. and to alleclinj; n portion of 
tiuil r>f|:ao as to give rise l>y roflci action to impulses which descend the 
nfi as inhibitory impiil*es. The jwrtinn <if the medulla thus mediating 
Wwntp the atlercnt and eSerent impulses may be spoken of as the rardio- 
UkOi i k r y er^iln-. 

1ts0ex inhibition through one vagus may be brought about by stimulation 
flf tbe c«Dtral end of the other. In general the alinienlary tract seems la 
dner niooection with the cardio-inhioitory centre than other parts of the 
hdy : and if the peritouewl surface of the inieslioe l>c intlnmed, very gentle 
MMalalion of the inflamed surface will produce marked inhibition. But 
a|ifiarratlv Ntimuli, if stifBciently powerful, will through reDex action nro- 
■loee inhibition, whatever tie the ]hu-1 of the body to which they ue appned. 



Thu», LTU^tiin^' a frog'ti foot irill Atop the heart, and ailequKte MimuUiion of 
niofit ulIbrv'Qi iicrvea nill prcdiice some aniounl ul' inliibiiian. 

TIte detaila of tlie reflev ehiiin ati<l the portion of the i-entro oonnnm) in 
itie iJerelopment of augmenting iiTi|)ulM« have not been worked iml so fullr 
an in the cnse of inlilbiCdrv im|>ulM.'». hut there can b«i lit(l<- iloubl that lh« 
former, like the liillt-r. are govL-riied by thi; (.'ciiLnil imtvuuh hvtU-wi, 

i:I60. Si> t'lir we buve bi-en deullnft with thr heart of the fmg, but the 
main fad>> wbieli nx* bavc- eljiied re^rding inhibition and nugmcnintion of 
the lifurt-heiit a|i|>]y hIbo to other v^iebrntc! nnimaln, inchiding mnminak; 
and, iixleed, wo meet similar phenuntciia in tlw hcorla of invertebrate 

If in II mammal the ht-Art be esnnacd to vieir by openinj^ the thorax, and 
the vngnN nerve be t'timtiliile'l in tnc nrek, the heart lony bo se«n (o stand 
still in (linstole, with all the pari* flaccid and nt rest, if the onrreni em- 
ployed Im- twa weiik, the result a« in the frog m not an actual arrest, hut a 
Hlowinc or wenkeninf; of ihc beaU. If a liuht lever be placed od the heart 
a graphic record of the i^tindetill or of ihc slowing of the complete or incoai- 
plcte inhibition mav be obtained. The reaiilt of etimnlating the vaguti is 
also veil »howii on the blood pressure eiirve, the eflect of complete i.'arHiiie 
inhibition on blood-jireeanre oeing most striking, If, while a traeing of 
nrlerinl picture is being taken, the beat of the heart be suddenly nrrmied. 
eome fiuch curve oh that represented in Fig. 96 will be obtained. It trill Ih.- 

riu. Mk 

TaxrnmSaov\%n Jilt«!ti or CtMHMi tsHontioK ■>!■ Bino)>*yu»nmx. Fnut a EUarnr. 
I. Ihr maiKt oil ilip ilgnul lino w)i*n Ih« current !■ Itiruwii Intd, niiil y. utiut olT tmm Iha niftii. 
nui UuiC'iuukct bBlaw mnrb Koniili, Ihe htmrt. lu it CKqucMlf thv eao In tha nbMt. Imbubc 

obaenred that two builn follow the application of the current marked by the 
point a, which currenponds tu the signal -r ou the line below. Then fur a 
apace of time no heals at all ore aeeu, the next beat b taking place alinuit 
inimediiilely al\vr ibc Hhuttiug off the current at y. Iiumediately oiler the 
Wt lival fotliming a there u a sudden fall of the hlood-preeeure. At thv 
pule*- due tu Lh<! Iiwl fvstiile the arterial ti\->tt-in la ill itja niaxiiuuni of diirieu- 
tion ; j'firthwith the eliiaiic reiii'tioR of the arteriid walls pi'opels tlie blood for- 
waid inlu the vein*, and, ihere Iwing no fresh lliiid iiijci-Ied from the heart, 
ihe fall of the mercury in unbroken, being nipiil al iirwt, but alower afterwanl, 
w llie elsnic force of the nrtcriid wall* u more and more uiwd up. With the 
reluniing beats the preMuru corresjnndingly riac* in encccwive leMpa uuUI 
the normal mean preasura ia regained. The sii» of these rvtumiug leapt of 
the uiereury may seem dispronorlionalely large, but it miMt be remembered 
tliat by far the greater port of the force of the (trat few strukea of the heart 





m mimmIwI En dbuodiog the artvrU] sjsl«in, s rrisII portion <Hily of tlw 
blima whieb is «j«<4vd into iW urteries paoring on into th<i vriiu. A* lh« 
aruriAl prcwnre ri»M, rioiv niid iiiun- blood pamm at «-HL-h I>«hI through the 
eapiHann. and the riae of tho prtaaure at each bent bwomcs Ivts aim Icbh, 
until at Ia«t the whola maUota of the ventricle poM it eneh stroki- into the 
win*, ajxl the maaa arminl preMurv is «tablishcHl. To thi« it may Iw 
•ddcO that, aa we have ttVD, tiw force of the individual bcnU mar he eom»- 
what greater aft«r than before inhibition. Bcaider, wlwo the raerc^irrmano- 
laKer ■• uacd, the inertia of the mercury lends to magnify the rffects <il' the 
initial beau. 

In the mamma] mhibition may be brought about by iiDnuteea paseing 
•iuog flbra which, starting io tlie medulla oblungats, run doirn over the 
ragiM nerve and r«ach Ibe heart by tlte cardiac nerves. Ii would appear. 
bowvrcr, tfaat the iuhibilor}' fibn^ do not belou); to the villus proijer, but 
lean Ibe central nervous sys[«ni by Ibe suinal avi-essary ner^'e. Thuit if the 
RWO of tb« »j>iuai tuxeaaary be divided, tnoie of the va«us proper being left 
tntact. the «pinal acoeaury likrea tn the vagiDt trunlt iKgenerate, and when 
this laka place »tiniulaiiou of the tu^ud trunk faila to product; the ordiiinrr 
inhibilitrr rlTectii. In th« manimni, a* in thu frotc, inhibition may bu brought 
ab>Mt nik imly by artificial ntiinulation of thr voguK trunk, but by tiliniula- 
tioo in a redcx manner or othvrwiiic of the carilio-inliibilorr oe.nlre. Thu.t 
Um fainting which often follow* ujwn a I>low on th« »toin»cli ix a repetition 
nf tlM rvult just nientioned u obtained on the froc by striking the stomach 
or atimulaung the oerri roeMntcrid. Ho also ihr fninting, complete or 
partial, ithich ncoomnanics teTare pain or mental emotion, is an illustration 
nf <»nliac inhilntion by tho vagus. In fact, cardiac inhibition so far from 
baang a uiera laboratory experiment entera rcpealcdiy into the erery-ilay 
trorkinK of our own organism as well as that of other living bdogs. 

Indee<) there is some reason fur lliinkiuK tbal the eentral nervous system 
by means of the cardiac inhibitory ttbrea keejM as il were a coniiuual retn nn 
tM heart, for, in the dog at least, section of both vagi causa* a quickening 
of the heart's beat. 

In lb« dog the atigmentor llhres (Fig. 96) leave the apiiiul con.1 by the 
aotrrior roots of the second and third <lorta] nerves, ])owibly aba to some 
extent by the fourth and liftb, jitua along the rami (ummunlcanles of those 
Bervsa to the ganglion >tcllatuRi, fir^t tlioracic ganglion, or respectively to 
saa or other of tho ganglia forming [mrl of tin- thoracic .iplandinio or 
vvnpathrtic chain immediately below, and thenco upnanl through th« 
aonolu* of Vicuiwvns.tnuiiug along one or other or L>oth loo[)«. to the inferior 
Ma t ka l ganglion. Tneir further course to the heart i* along the nerve* 
sprini^ing oiDwr from the inlbrior corvical ganglion or from the loop of 
Viaiaaens dim-tlv. Their exact path from the ganglia in fact teem* Io vary 
ia dlSrsnt individuals. 

Tbe path of the augmentor fibres has not been worked out »o fully in 
•Unr BMmnuila as in the dog. but it is moat probable that in all ca^es they 
bare the sninal cord by ihe anterior roots of the ^cond and third donal 
aarres < possibly also by the fourth and tiftJi) and. pawing up tbe sympathetic 
ehaia to ilie gaoflion stellatuni and annulus of Vieussens, proceed to tho 
bout by nerves branching off IVom some part or other of tbe annulus or 
froai tbe lower and middle cervical ganglia. 

Tbe oflbcts of stimulating these augiueutor fibres iu the mammal are, tn 

MMral, the aame as tliuse witnessed in the frog. In the mammal us in the 

tnf Iraplilars along iboN; augmentor fibre* may \>t ur^innliHl in thi- citilral 

1 nai I inn srstcin, and that pr<>biibly in various waySL That jialpilaiion uf the 

1^ bnrt akich is so conspicuouii an efled of cvrUiin emotiono is protmbly due 



to the aiiddeii poeilive boUod of augmmling impulH«. thuuj^li il ma; poadbljr 
be rlue. lu pari at Itinst, to snddMl wtthtlrimni of iiormat, coDtiouoiM, tonic, 
luul inhibitor}' impulses. 

IiixiHiMiaaTii' KiTtiJannimoK or laa cui> 
iirjiL iHiriiiiioBV t>o Atjoatma Pibnb 


II1B upper poitioii of Ui> titan npnasnU 
U>g InhltilLoiy, tbfi lower l)w wisnuDior Abrai, 
T.Yv., raotaoT the new; rJip.Xe.. rcnu«if Um 
■l^nitl ncrauory: boUi drawn •my dhjft 
iDfttlullr. (iJ.RaiiRllos jnsulan: u.Tt.Vc-. 
^[ikIIuu tniiii'l ngt : ^p-Af., i|4iib1 a mn wy 
liunk : Kxl J1|i. Ar . cilmuil ipliuil w c«»i.ifT j 
ISr><Ac.. Iniemal (plnalaucnaurr; Vr., tnink 
of v*tiu> iivrvB : 11.'',, bninchBiiroliii; lolinut-. 
C.lji)r««rtlMlt}mi«thi!«li<: (i.C Inner cwrvt- 
Ml vuigUoD : X.tb.. futwlavlan arury ; Aa.V, 
JUmiilluor Vtmmam: O.W. >Tb.<), fUfUoB 
■fcllatum or am ihoiulc ssdrIIoo ; U.Th*. 
n.Th.'. o.Tb.i. Hcond. tbltis. kiiil latinli Ik^ 
raiUccttnilla: n.II., [>.I11., I>1V.,I> V. Mcond, 
Ihltil. fbnnb. uid nnii ihcirnr)cii4iAlDtrr«>: 
ijt., TKiDui cummuiilnuu : n.v.. ii«na Kal>' 
dlacj lawlnt 10 licatl inipeitca raoa M**) 
fraoi nrvlnl (uigUbti unl Itoui tlic uinuliH 
of V'leaaciui 

Tlw labltdtoTT flbra*, Aowa hf lilncl Ilnr. 
run In Ui« iipp« imtduUur tnuu. <a ibo 
■l*nkl ■cotMOty. b; the Inlenwl bnacb of 
itiu >4>iniU kMKaiory. |M>t ibe MnRMoo Iranel 
vuKi' iiliiug Iho iRink <■( Uin nKiu. kud M by 
limncbn la ihc lUperlar nna can aiul Uw 

Till' >iii|(in>'ii|i)r nbm. alfo •hown t>r tdMk 
line. iBH [n>iii (Iwiiidiuileoidli)' ibeuMstor 
Kvit^uF Ettr *4<i-i*ijii Aiiii ihjnl ihara^c nfrrvn 
.jitHiilily ii\f rroin itoiinii and anii u In^i- 
.'ndfl ti> brukiii black lliio). paai the Mwoil 
uid i)t>i tHiollHivi thoracic (■iiirlla tiy tli» u^ 
iiiilut III VlsuHriB l« Uia lowrr nnlokl tu^ 
rUuii. 0(1111 wbtncc m kIm (kuni tb* uioulai 
ItwK, thrj' lan alnng llw cartlac ntrro ta 

In tlio RiunmBi tben as in the hog, (lie heart !» g»vciti«<t bjr two fels uf 
avntt, tbi> on« ■nlagonietic to the ol]i«r. lii the dug llic moU of tl>o «j>insl 
ncixetoTj Dcrre, bf which inhibitory &bn» leave the (X-ntntl nervous sTsiem, 


Amoog tbwe are fibres of line 
be usom) linwa the tniok of the 

^HHJ^^BbUrIj of medullated fibres. 

raguB, ftkmji tbr hnin<-b«9 t:iiinf; to tbe bmrt, right i)i>w» to tbe beart ilself. 
TImk mn Kb llUle doubr tbcit Hicse rootultiitoi) fibm of line calibre are tbe 
inUbilorr flbm of th« va^nia, noil inilr<^l Un-n' \» evitlenoe whicli r«uders it 
pmliable tbit tin: iiihihUorv tibra of tb« bi-nrt arr nlwByi> metlulbted fibres 
«t fiM CftObrf, H liHi cuntiiiiif a« modulUtiil librr# rif;l>t ilown to the beart, 
bat •waltnllf loao thtir medullx in th<< hrnn itM-IC. 

Tb« nucrior root* of tbe tocond nti'l thin) ilorMl iMin,'m. nod the (ithiu) 
tmal eofDraanicanla* belonging to th«Di. which. a« n*u hava jtwt swa. contain 
ia th» dog augmenlor fihrw, alsci consist osclnRively of mod u I lit led lihita. 
Bat tbft n«rr«s which convcT tbe augmenting inipuJK* finni tbo |nin>r 
c ar TifJ noglion or from the anuuluB of \'ieiiMcn9 to the bmrt coniuM of 
aott-KiedallaMd Sbra, Hence, the augmentor fibroe must bave lost tbdr 
Mtdulla and become contiitaouii with non-medullnle<l Rhnt somewhere in 
tWr cuurw alontc the ivinpathetic cbaiu. It \a probable that the chnng« 
oecan in tbe^'anj-lion Bt«llaliim aiid lower cervical x''>')Rfion, and it i» further 
probable that thi- ihant^? L-> cfll^-ied \>y the mediillato<l fibre pna§in|; into one 
flf Ibagaoitlioti celU, ami Bvluing ita meilulla, the iuipul»cfl which it coorova 
pMriDK out uf the nerve oell by one or more of the other procewn of tM 
e*ll wftkh ar* oontiiiuad on as non-mrdiillHti'<l iibres. Cf. § t»*. 

la lk« dog then thcM two sats of ni-rvc fibn«. antagonblic to each other 
to function, difler in Mnicture, lh« atigmi-iitor Kbres early lonng their 
Mtdulla and heneo being over n large part or lh«ir course mm -medu listed 
flbna. wbrmu th<- inhibitory Hbrea are in«lullat«d fibres whit;h lluiu^b they 
may paoa b^ or Ihruiiub g«iiglia (as the ganglion jngularc and (.-un^liou 
tmoci rasi) do not lose thfir medulla in ttiwc ganglia, but remaiu aa 
■srdullalea librts right down to tlie heart. And this dinereooe in Ktructnru 
afpeara lo hold goo*) for all muniinals, and is possibly true for verU-bratcs 

I in.' Tbe qnflKkn, what i» the exact nature of tbe change braught about 

by tbe inhibitory aud augmenting impnbfti reamctirely on their arrival at 

tbe beanT or, in olhor word*, by virtui^ of wliat events nroflnccd in the 

beait itself do tbe tmpuUvs of •>iic kind bring alKiul iuhibition, of the 

StlMr Itiad augmentation T b a very difficult one. which w« cannot attemtit 

to ill can ftillv here. We may if W please «]wak of an ** inhibitory mecli- 

ttimm " nlui-il in the ht-jirt itMlf, but we bavo no exact knowledge of ihe 

aUan of such a mecluuiicm. dtill los do we powow any wittiitactor>- inform- 

•lioa ■■ lo am augmenting mechanism. It has been »ugge«t«l that Mme of 

tbe paglia in the heart serve as such an iiihibibiri- (ut augmenting) 

■KUtusm ; but there ia evidence thai the inhibitory impulses prnduee their 

•Am by aettng directly on the muscolar fibres, or at all ovenu do nut pro- 

daca tbsir e^ct by acting exdiiaivelv on any ganglia. One evidence of 

this jttftd is sapplieil by tbe action of tne dniji atropine. 

If, eilher iu a frog or a mammal, or other animal, after the vwub ttbree 
Wic br«n pn>veil by (rial to produce upon Kitmulation tbe usual inhibitory 
efct*, a ■mall quantity of atropine be intnKlnced into lite circulation Cwlien 
ih* •iperimsot b conducted on a liviii); animal, ur be applied in a ncalc 
snlutirai to (he heart iiiK^lf when the ex|ierimeut b eonduoted, a» iu (he i-*»e an oxi-iiaHl l>eart or after ilie rircu)atioD baa ceased), it wil) al^er 
a 4wt tinve he fotind not only tliai the Hlimiilution, Die application of a 
cnrmt for inMance, which previously when iipplii-'i to the vagus produce"! 
Barktil inhihilion now producci no inhibition, but even thai the i>lr(inmi 
NiSNilu*, the strongest current appli<i) to t)io villus will wholly faif to 
sftvt ibe heart, provided thai there tw no 0Ma|>C of mrrent on to the cardiac 



tiMUM ibvmsdvts ; under the inHtioncs? of even n nnall iwv of ntro))in?, ibe 
BtrongM slimulation of the vngii>s will not p^^duc« ilaiiijslill or npprcaablc 
slowmg ur weakening of the k-nl. 

Hon it tnighl be suppoeed thut the atropine producer this remnrkable etTwt 
by acting on some gnngliooic or other mecbanism intervening belive«n ibe 
va(;uB librei and ihe cardiac muscular tissue: but we have evidence that the 
atropine acts either on tlie muscular tiaeue itself or on the verjr eodingB of the 
nerves in the muBcnlar fibres. We have said. § 155, that a properly prepared 
Htrip of tbe venlricle of the tortoise will execute for n loii^; time spoutAiteoua 
rhytbiuic contracliuns. it will go on " beating " for a long time. A strip of 
the auricle will exhibit the same pheaoiueini even etill more retidilv. If now 
while auch a strip froui the auricle ie saliafnctonly beating a f^utle inter- 
rupteil Diirrent he pan^t^l through It, it will Htop U-ating ; tbe current iuhibits 
the s|)ciu[aiieoui beats; a very j^itle iiiternipKit curn-^t mu>l Iw u!>ed, 
olhurwim: the eflbct 1* obacured by ibn mon^ direct stiniulatin^ m-tion of the 
currvnt. If now the xtriii hi' gently bathed with n wenk nobilioii of alri>pine 
no Much inhibitory clK^t is prudiiceii hy Ihe intiTnipi<'d rnm^nt ; ihi' Iteata 
go on ri-gardtetiH uf thi; urtion of the current. Thi; ititi-rp relation of thU 
expfrimi-jil in that in the first case the iiilernipled citrrcnt slimuUtrd tho 
fiiK termination i>f the inbihittiry iibres in the muacnlar strip, and tbnt in 
tbe second caw- the alrcipino pr<iiim«d smne ofiect eith^rr on lh«e line librcw, 
or on their connections with the muncuUr sulislanoc or on tbe actual mns- 
cular sub«t»nro iUclf by virtue of which they ceased to act. But if this be 
so, if the entnc inhibitory ctlcct« tttw produced alike by etimulating tbe vaRua 
trunk, and Btimulatiug the vorv cndnigi of the nerva in tbe muscles of tbe 
heart, if not tbe actual muscular tiesiie itself, then there is no need to 6up- 
p(«e the existence of any special inhibitory mecbaaism placed between tbe 
tibrc8 in the VBg;us branches and tbe cardiac muscular tiasiie. 

Till.' action < f atro|)in« on the heart is. so ti> apeak, com)d«m«Dlcd by ttie 
action of muacarini;, the active principle of many imiNoiioua mnnbroora*. If 
a small iiuuntitv of mtiscarino be introiluced into the circulation. orapplM 
directly U> the ficart, tbe beats bwrjuie *l'iw and fetible, and if thedoM be 
adequate the heart is brought to a coniptet<r iiliindiitill. The fflect it in vonie 
respects like that of powerful »timulatinn of the vaguf, but tho staiiil^till is 
much more complete, the ellecl is much more prul'i'urid. Now if. in a frog, 
tic heart be brought t" n flandiilill hy a d<i»e of m»»cj»riiie, tbe application of 
an adetjuate <|iianiily of nlropini- will bring back the beal# to quite their 
ni>rmal strength. The one drug Is a* far tui tho heart is concerned (and, 
indeed, in many other respects) the antidote of the other. And, as in tbe 
aae of atropine, so in the case uf muscarine, there is evidence that the drug 
acts not on any ganglionic mechanisms but on tbe cardiac tissue itself. 

Tbe conclusion tbat inhibition is the result of changes in the cardiac llssne 
itself may »en'e to explain why in inhibition sometimet) the slowing Mime- 
tiroes the weakening b tbe more prominent. When the itibtbilorv impulse*, 
by rcawHi of particular fibres l>eii)g atfected or otherwise, are brought to 
bear dti«fly on ihooe [lart^ uf the heart, such as the ainun, which pu»»e«lng 
higher rhythmic ixitejiLiality (tutt ^ 156) deiermiue the Ae^uence and set the 
rale of rhvthm, it iii thti raiv which i» moat markedly airi'i^led. Wlivn, on 
tbe other bBn<l, ihr^ inhihitory tnipnlnes fall chiefly on llic paria {i><w<i>e>ing 
lower rhythmic potentiality, Ine nuwt markc<l i-Heet is a diminution in tlie 
force of ibo coniractiona. 

There is no ade(|uatc evidence then that tho citnliac ganglia act n» an 
inhibitory iuecbani*m in tho sense that they prmhicG imiKirtaiit changes in 
the nature of the impulse* reaching them along vagus inhibitory Iibres before 
tJiose impulses puss on to the muscular tivue. We may add tlial there is 




H in; 

ftmilftrly no MlMjuate BvidcDoi- ihat nDV of the ganglin act ns xii " nu^mt- 
iBg " uodutiUni. We have piTvioiHly iwn, $$ lu'i, 1-06, rca«oiie for thioking 
iIm nogUa nrv Dot ccniras for tbd ori^oulinii or reeiilntion of the gpoutaiiA- 
iiiM liMli Tbe qucBtioii ifaeo ariipw, what are Uicir fimdionaT To this 
i|ilHliaa «« rnuiiot at present fyn a wholly luitisfacloiT aoBwer. 

TTmi inblliilory RbrM reiuuin, bb we have Mea, niMlullated libm until tbcy 
i««rl) ihc bdArl, btil it would apjK^r that tb^ lose thdr medulla, somewhere, 
in tbe h«»ri before tJi«v actually reai-h the tnusculkr tiwuc, and it is probable 
that the luM takes place in cuDiiecliou with aowe uf the cardiac gaDglia 
much in the Mioe way thai tbe auj^eutiuK librea loae their medulla in Ibe 
ganglia of lh« rrBipathetio obaio ; but we do not know whiil is tbe pbyai- 
olopal effect or Uw purpoae of this Ion of the medulla, aud we caunot 
MppoM that tilt* i* iJk aole or eveu chief use of the ^njilitu Coinddenl 
with ibr luM of tbe iiwduUii nn inrreaie of fibres fretjueutlr lake* place, 
Bvorv than one non-iiirdu Hated fibre lea<niig a uervi? cell into which one 
aaadullaied fibn t«ter> ; an<l we uajr auppow that ihla ntoile of branoltJag 
baa ninoMa am fulfilled by tbe mere divuion of a fibre. Then awaio bearing 
in awM Ibt nutritive or " (mphio " function of the apinal ganglia alluded to 
in i 100, w« may luppn-e that the cAnUac ganglia arc ia wme way coDcemad 
ID tike nutrition of the cardiac ii«rv« &hr<«. Ittit our knowlodge is not yM 
Mttcieotly ripe to allow cxart itatciDmta to be mailv. 

Oiker Injla«neei Regulating or Modifying the Beat of tite Heart. 

i 169. Iniporlant as is tite regulation of tlie heart by ilie nervouji iTiileni, 
it ntMt be burae in miml that other inAuencee are or may be at work. The 
bwtnf the lieart niav. for iii*iiiiu>- h« modified by inflm-iit'ot bearing directly 
t» iIm tiiilritioD of the heart. Thv (iiwtiCM of the heart, like all other tissues, 
D«e*l an adequate sopplv of klixHl of a proper quality ; if the blood varyiu 
quality or i|uantily tne Val of the heart w oorretp'mdiiigly aflbcted. The 
U(C)M<1 fruc's heart, as we have aoon, cmliuiHa to Mutt fur some OOtuiderabla 
titoe, lluiugh apparently emptv of bknd. After a whilv, boirever, the beata 
dimlntsh and dimppear ; ami their diMppearanoo is greatlT barieoed by 
waafalng out the heart with a nornial saline lotutioo, wnieh wnen allowed to 
flow through the cavities of the heart readilv pemeaiea the tiiauei on account 
OiT tlM peculiar construction ($ ]ol) of tlie ventricular walU. If sue b a 
" wobed nut " nuicttcent heart be fed with a perfusion canula, in Ihr manner 
deecribtd (§ 155), with diluted blood (of the rabbit, sheep, etc.), it niay be 
iMIiiiiil to Amctional activity. A siniilar hut lew complete natotaiioD may 
be wftavMcd if sonim )w umhI i&Htead uf bliHHl ; and a heart fed r^[ularly 
with froth Mlppli<« of blood or eveu of ^rum may lie kept iMitlng fur a 
fWT gnat kngth of tin>c. In treating of tlie akt^lelal iiitiwliii we «aw that 
fal UMir caJr the exhaustion following upon withdrawal »f ibc blood^otrcam 
aaicht be attrilniud either to an inade<iuate xujiply of new ntilritive material 
and oxygeo, or to an accuiniilalion in the niuiu-iilar Hutkttancc of the proilucta 
of muscular tnetabolUm. or M Ixilh cnuMv combined. And the aiue cod- 
ndentioiM hold good for the ncn-ixiR and muwular itruc4ura of tbe beart, 
though the aubject hsc nt>t yet ttciu ^udicicntly well worked out to permit any 
vary definite MaleaienLs to be mn<le. It cwms probable, however, that an 
impoirtant flutor id the matter is the accuiutilntion in tlte muscular fibree 
maa bl the surroundiiii; lymiih of carbonic acid, and eepectally of the 

*T'Tf which give rise to tlie acid reaction. 

When the frug'i heart ia thus " fed " with various substancee the InterM* 
tng fiwt i« brought to light that ■ome Hibelonoes, sueh for instoDoe as verj 

:.■■!■•. such I'lir iiisiitiii.' 
■-..I-- '.■xjuiri^iiiii, thiti i^, 

Wiilllll U|)[H'!II' [Imi 

!■ .p rlivrliriiii' i'iiiitr;tr-- 

!■: Mill- lIllV iiri' Inll^i-r. 

■■■: illv ililiili's lii'VMinl [hi- 

'he veiiiricli'. w'nU t\i>- 

Miiiil. Fiirlli'-r, iri ili. 

• - .riiL'tlii'in'il tliL' rfl;i\;i' 

.'.■i]«irt.'nlly thi' vi'Uirirl-- 

; "i.-It'il wliiii ;i new lii-;lt 

•>- - I '.i: w.' shitll ,-[ii'!ik lit' ir) 

. anil [he aiiLniiiit i>t' [iii- 

■ M.::v lit' llii' vriilrii'li.', varii-> 

- -t7. 1-vilk-IIC.T tluit illlllliitiil V 

"a.^k' tltU Ionic cuiitriKiinn. 

'■! with siTiirn iir cvi-ri uiih 

i-'i h_v -tiiiiiiliiti'iti, lu'i' ;i|ii Ili 

-. s ^(ii L'rlUl[l^. This inU'i-niii- 

_ uniiljk' ii>c'iiiTV on iiiitriti"ii 

st'<|Ui'nl |ii'<Hliii'ti<>ti uf aliDiir- 

a" fiiriliai' inliTniiiii'in't's >t^-n 

,iii>iu- chi'inii'iil siilij'iuiK'i-- in 

■|U' lu-ni'['s ln'at l)v aulid;^ "ii 

-. 'I' liiilh. anil [liai [iriihiililv in 

^ ih*.- rhythm, nv thi- iiiiliviiinal 

-. ■ ■- ■[' ihc hcarl alsi> alli'cl its Ixai ; 

aiiiLiiiiit III' th<- <li»ti'ii(i<i]L 111' it.- 

. -. '. , liki' ihiJM' i)t' nriliiiaiv nuisih- 

■■,ii Ivy llif ii'.-isiarice whii'li thcv 

-.iii'i' lhi(i;;s ln'in^' tijual. vndiraii 

. , ■. a.- ill ixiliiiary niiisck'. tilt' limit 

.i-*i<i, am! an Dvcrl'iill ventricle "ill 

. [iriilialily tiuiptics it-dl' ciiiii[ili'ii-lv 

■ ]nanlily nt' 1>I I in the vciiiiiclc 

' ivs: lilt' i|naiiiity ilirown mit w^iiilil 

« 'iihl III' ('ifc'icil «iih ;:rcatct' I'nicv. 

■■;rii'lc i- .at the cinnnicnccnu-nl .if 

;-■ aiiiii'iihii' systiilc. the smrk nC the 

1 ■ '.•.■'■ is ill a measure triiveriieii liy thr 

•■■. nui'lianical ili^iis anil ilulirect iitr- 

■■. iieait's Inal til 111 i-]ircssnrc. When 

- lie resi-liiljce I'l the Velltlienlur -vslnle 

:(!. iiiiin.' Kliiiiit lliiws I ill the iiianiina- 

. ■.■.■\. I'.LTtli these eveiil,- iviiuhi itiere.i-e 

;'i; ex|ii'el tlial the itierease «iiuhl lie 

i^ «ell as ill the I'lPi'ei- «i' the iniliviilnal 

»e i| I li;ii| ilii-, < In the ciiiitrarv 

- ■■, may hi- |iiii alinnst in the liirni i>r a 
■.'.Verse laii'i In ihe arlei'ial [iresffUie : " 

'.'- 'IV a iliitiiiiiili'in. aiiil I'all nl' iires-iin- 
I'iiii*. li'i»tvei'. I'lilv hiihl» I'liiiil if ihe 



ra^ (ig iuuu'U If (Imw )>e previnusly dirliled, then io irhaUvor wny th« 
MtMiH-praMU* be nUsed — whether hv injet^tiiitc blood or clam(>iag the Horift, 
or iatnamtg the iierlpheml rtsiauuice. ihrouieh thut uoii»ii m' tb* vonomotor 
Dtrres wbien we shall harv to clfvcrilM.- ilim;(lr — i>r io wbktercr my it bo 
lawcKd, wtaudi clear and il4ft<l(yt invcmr rclniitjii betir«en blood-pretnare 
■sd pube-rate u olwerrcd. li 'n< Infvrn^i. iharvfove, thHl iiicrrnsol blmxl- 
fiw ufe cauM* a riowtni^ of th<- pi>l*r, wlton lh«^ vagi an- ititncl. bi-ctiiiw: [he 
fvnit'i- inhibitory c^ntro iti thr niviliillii U xtimulnltHJ by th'* Wt^h yrvMorr, 
cittwr dimply by ihv prrwun' obliiiiiing in tb« bloodvexmile of iIm- mriliilln, 
or ia aoOM indirect nianiMr, a»d this hrart in ooosmuence to a «crKiin extont 


Action I*. 


f 163. W» hav« seen r§ 108^ that all arleriM coolnin plain muacular 

ftbm, for tlie nivot nnrl circularly iliiijHinL-iI. and itiwt abundant in, or M»ne- 

timr* alin(»l rntirvly oonlint*! to, ibe iniddlu otiut. Wl^ biivc furtbtirseen 

that a* ibr nm-riea beeonM imnllvr the nimciiliir rlumcjit. tu> n rule. Innioaiu 

nkorvand mure prominent » Gonipiini] with tlu- olhvr Htrmciit*, niilil, in the 

Bunuir artvrieii. the middio cont onsiota almost entirelr of a series of plain 

Biw^br fibres nrAp|)C<t nrniind tht- iiilcrnnl coat. Kervc tihn-*, of whote 

aaiiin' and muree we abtill prcatnilly »|>cnk. are distribute] Innn-'ly to the 

atVno>,and a]>pi.iir (o end cbicHy in line ]>Il>xurgs around thci nmsnilnr fibre, 

Wl dirir exact temiinatiunit have not a* yet boon clearly niiuii; out. By 

ntcfcaaical, el«clrical, or other uimulntioii, litis muscular coat may, in tho 

livBS artery, W iniule to contract. l>iiriu^ thin cnutraotiou, which has the 

tlinr chamcier lx.-liiui{int; to tbe contructioua of all plain luuade, the calibre 

U thr vomoI is iliraiuiiihHl. The veins also, a« ue have wen. poasen min- 

(alv «temeDt>, but ihnr vary in iimoiint and dlMribution very much more 

iatbeveing than in tbe anfrir:>. MimI vdoit, bovrercr, are oontraclile, and 

■avrary in calibre acconliiij; la the cunitition of their muscular oleoieuts. 

Viki are also mpplic*) with ticrv«s. It will l>e of adviintage, however, bi 

omUar aeparaloly the liltlc n<! l(iH>vr cMicerning the chiuigca in the veins, 

aail \o ODDnQe ouraelvn at pm>ciit to the change* in tbe nrtcTie«. 

If the web of a frne's foot be watched under the micmmnpe, nnv individual 
Mallanary will be found to vary coDnidcrnbly in calibre from time to time, 
Uv ■oaMtinwa narrowed and aometintc* dilated ; and tbrso changes may 
Hhl place without any obvious changes either id th« heart-ltcat or in tbe 

rnl circulation ; they ar« clearly changes of the arterr itaolf. Diiriog 
Darrowiuit. which i* obviously due to a cootnwtJOD of tbe muscular coot 
<f the artery, ihc cHpillarics fed by the artery and the veins intonhicb th«S 
Ind become leaa filled with blood and paler. During the widening, which 
aSRqwnds to Ute relaxnlMXi of the muscular ooat. the tame parte are fuller 
rf bUisd and redder, (t ia obvious that, the pfeesure at the entrance into 
■aripTai artery reDisiiiine the uiue. moro blood will enter the artery when 
iwutioa takes place, and consequently the rcfttatanoe oBered by the artery 
iidiBfailalied, ana lees when contraction uccura and tbe resiaiauce t» conso- 
ipmly incrensea) ; the blood flows in the direction of least reaislnnce. 

TW extent aixi intensitr of tlie narmniug or nidcniiig. the ooaatriction or 
Alin which mar thus be observed in ibe frog's wel>, >'ary very Inr^ly. 
VuiMiooB of Alighl extent, either more or less r<^lar and rhythmic or 
fal^plar. occur oven wIm'u the animal ix njiparentiy ■ubjected lo no diaiurb- 
fag liases, and may be ojwken of as ^MuUneous ; mrger changei may follow 



events occiirriii^ in v&rioUB pRits of the bodr ; while ns the mull of exp«ri- 
meolal iiit«rfeivnci? llie srt«ri«B may become either eonslrictml, in eonie ca««e 
almoflt t'> obUteration, or dilaled until tliej* tic^uire double or toon tlmti 
double tbeir normal dinmeler. Thit^ conBtriclioii or dilation mmr be 
brouffbt about not only by ireatnieni applied direotly to Ibe veb, but also 
bv cliaages aDecting tUe nerve of the leR or other parte of the body, 
lliua, Mcliori of the sciatic nerve is (tenerally followed by a wideuin^ wbieh 
mi^ be alight or which may be very marked, and which is sometimes [>re- 
oeded by a padding eunatriction ; while stimulation of the [leripheral Mump 
of the 4)ivtdeil nerve by an iut«rrupted current of moderate inteusit^' gener- 
ally given rise to conslriolion, often so great ns almost lu obliterate aotne of 
the miiiut« arterlM. 

Obviouifly. then, (he contractile mii^rular elements of the minute arteries 
of the wch of the frog'ii fool are capable by coutruction or relaxation of 
caujting dfcrrnw nr IncrMuwof thi? calibre of the artcrie*; and this cnudltion of 
Con«tricti()n ordilatton may br brought about through the agency of the uerve*. 
Inilci-fl, not only in the frog, but hIm), vud utill more so. In warm-blootlvd 
iinimnK have we cvi<U-ncv Inat in the CB»e of nearly all, if not all, the arU'riM 
of the bo<ly, the condition of the muKCular coat, and fo the cidibn- r.f the 
futery is governed by means of nerves; these nerve* have received the gvo- 
general name of mMimolor »(nw, 

S 164, If the car of a rabbit, preferably a light colored one, be held up 
before the light, n fairly conepicuoiis arierv will be seen ninning up tli« 
middle linear the ear accompanied by its broader and nwre obvious veins. 
If this artery be earefiilly watched it nill be found, in most inataacM. to be 
undergoing rhythmic changes uf calibre, constriction alternating with ililatMO. 
At one moment the artery ap|>enrB ns a delicate, hanlly visible, pale streak, 
the whole ear being at the same time pallid. Atler a while the arter}- slowlr 
widens out, becomes broad and red, the whole ear blushing, and many smab 
vessels previously invisible coming into view. Again the artery narrows and 
the blush fades away ; and this may be refteated at Humeuhnl irregular inter- 
vals of a minute, more or leM. The extent and regularity of the rhythm are 
usually markedly increased if the rabbit l>e held np by the ears for a short 
time provioui to the olwervatiun. Hiiutlarly rhythmic variations In the 
calibre of the arti-ri*^ have been oliserved In iwveral placM, t.y.,ln the 
vcanls of tile mesentery anil cloen'bere ; [irolmbly they are widely spreml. 

!y>motim<» no snch varintioni' are seen, the nrUrrv remain^* constant in n 
condition intermediate between the more extreme wiifening and extn-me nar- 
rowing just described. In fact, we may Rpeiik cf an artery as being at nnv 
given time in one of throe phaioa. It may be very constricted, in wbicli 
case its muscular fibre« are very much contractoi) ; or it may be dilaud, id 
which case its muscular fibres are ralaxcd ; or it may bo moderately con- 
stricted, the maseular fibres being cx>nlraeted to a certain extent, and remain- 
ing in such a condition that they may, on the one hand, pass into stnuiMr 
oanlrsclion, leading to marked constriction, or, on the other hand, into dis- 
tinct relaxation, lending to dilation. We have reason to think, as we shall 
see, that many arteries of tlie body are kept habitually, or at least for long 
periods together, iu this intermediate conoilion, nbicli is lire<]U«nt)y spoken 
of as tome conlraetion, or (okus, or arleriat lont. 

§ 165. If, now, in a vigorous rabbit, in which the heart is bouing with 
■dequate strength and the whole circulation is in a satisfactory condition, 
the cervical sympithetic nerve be divided un one side of the neck, remark- 
nblc changes mar be observed in the bluudvessels of the ear of the same «de. 
The arteriw and veins iriden. they together with the small vein* and the 
capillaries become full of blooil, mmiy veuels previously InvUble coiuc into 



"View, Um <rhole ear blufthM, mikI if ihi- rhythmic chnngc» described above 
««t« pcvriondj goio|; on, th>«o dow oeaae; unl, in cmiicqu^ooe of the «sira 
mppl^ of wmnn bloc^, tlw whole eur beooinm <li>tinctly irnrm«r. Now Oieee 
rliu>g«a uhe plsc«, or may take place, witlioiit nnr ■Ittrmtion in th<^ h«art- 
Ihsi or ill tbe |;e»cral circulation. Obviougly the arlcnr* nf llic viir have, iu 
iiiMmUllliliiii of tb« wctioo of the oerve. lost th« tonic c»ntrnninn whioh pre- 
riaadj exuced ; iheir muioular cohIji. previously fomewbnt. cotitraclitl. httve 
bMMlW quite relftXei), anil whatever rhythmic coDtmctions wi-rc pre- 
Tinodj going on Iiave ceaseil. The miire rnnrked the previous tonic conlrac- 
ttnn. UM ibe more vigorous tbe beArt-benta, hi that there is mn ii<lii]uaie 
Mpplr of blooil to Git tbe widened clianD«ls, tbe more striking the rMiilU. 
StHnettiDCi, ■• wh«n t)i« heart is feeble, or the preexist iufc tooic conUtaction b 
•Iwlii. tb« nection of th« nerve produce* no xm obvious chanee. 

If, bour, the upper Mgnient of tbe divided cervical sympaUielic aervo — 

tbM k^ tbt portion vt the nerrc pniinng upward to ibe bead and csr — be laid 

apaa dw eleeirodM of an induction machini.' amlaifcnile tmerrupled current 

b« Hitt through tbe aervc, new chanms lake phice in the hlixidvewela of th« 

tmt, A ■hiiri liniv after tbe application of the current, for iii this efTect there 

k a html period of very appreciable duration, tbo car grows [>aler and 

eeol ar , nany nnall vcskIs previoualy ixmipicuous become again inx-isible, 

tba maJB artery shrinks to the (hintmt i)ir>tid. iind the main retna become 

eami|MiDdinglr sniKll. When rhe current is »hui off from tbe nerve, theae 

«BhcU dill last some time, but eventually pan oR'; the ear rcddvnN, bluahes 

ooet mort. and indeed may become even reilder and bolter, writh the veoMla 

Bwn Blled with blood than before. Obviously the current hfu generated in 

tba emical sympatbeiic nerve impulses which, passing upward Ui the enr 

aad Boding ifaeir way to tlie muficutar coals of the arteries of the luir. have 

tbnea tbe niit*clM of thow^ omIk into forcible conlmctioDx, and have thus 

hna^t about a for<rible narrowing of the calibre of the arteries — a forcible 

tnmuietioa. Through ^h^^ narrovri.-<l vi>iu>lrivtctl arteriat lesN blood tinds its 

wvj, aad bcnor the [wlcntw and colitnm iif the ear. If the impulsee thus 

C'aied be vi-ry strong, the constriction of tbe arteriw may be so great 
Uw iniallMt iguantiiy oiily of blond can make ila way through them, and 
lieiarmay become almost btoodlen. If tbe impulM* be weak, the coustric- 
li<« bducM may be slight only ; and, indeed, by carclnl mnnipulatiou the 
■MTfl may be induced to send up to the ear impultiv only juici xulBciently 
Mn^ to restore the moderate tonic conetrictioD which existol before ibe 
aim wa? divided. 

We infer from lh«ee exjieriments that among the various nerve fibres 
■akiDtf up ibe cervical sympAtbetic, there are certain fibres which jMwiing 
apwafil tu the head become connected with the arteries of the mr, an<l that 
line tilirva are of ruch u kind thiit impuli^es };eneraled in them and jnmiug 
gfwsnl U- tbe ear, lend to marked cuuiraciion of the mu*cular fibre* of the 
ancrie*. and tliu.i produce eoiMrictiun. These fibres are vaaomotor fthn-a 
^ iw the bloodvewels of the ear. Fn>u the loc« of tone, ho frequently follow- 
H Bf section of tlw cervical iiympatlieiic, we may further infer that, normally 
H wiag life, imptibet of n giiitle kind arc eoiitinuall^ (lassin)- along thceo 
H Ara*. upward through thr r4;r\-ical aymjiathetic, which impulses, reaching 
P tk arteries of the ear, maintain tbe normal tone of thoee arteries. But, aa 
••■id, iheestMenceof this tone is not*o oointant, and tbfse tonic impiitses 
M not fo conepicuoits as tbe artificial constrictor iinpubea generated bj 
itimlalioo of the nerve. 

1166. Tbe above nviilts are obuined whatever be the region of tbo 
Mrrienl aynipatUetic which we divide or itimulate from Uk> upjier cervical 



^n);[1ii>ii In Ibe lower. We m«v. lh«^rcfor*, tlc«crib« ihwp viwomotnr im- 
pulse!! ua [iaBsii)g upward Irurn llic loner ccrvicnl ^ii^jlion nlone the cervical 
Myiii|)iilhei!i.', to the upjiirr mrvictil ganglion, rrom irhich iliev iwue br 
liniiK-hcA which uUiiimiely tiiid ihelr nav to (he car. Itut llitM« impulBes do 
not mart fnnti the Imkt cenricol gnnglion ; on ihe coDlran\ by repoitting 
ihe i'xnrriiii?i)t« »f ilivEjilon nnd HtiiuiiliilioH id a aeries iif iiuiiualh, nv mar 
tnict itic nnlh ol' ihrse imiiulHcs fntm the lower t-ervical ^iigtlon (Kig;- 97) 
ihroiigti iho annidu^ of Vietiswos lu ihe gaii^liuu lullatuni ur firM thoracic 

tiu«HA> lU.usraAtixa 710 Patih trr Vjv«<«<an«XToa Kiiiaai 
AixiKit TirE ctHrtcu STHfittHma a>i> (rin w) Tua ApommimU' 


Ami., >il<T)' ol«ar. 'i.L'.» . nipetlor orrrlotl puulWu; XIABpl.. 
ii[>)n' nuuurbni] |i*rt of al-lomlDii) a|iluioIiulc uarm: V.M.C «■>»- 
nuilor ivuiivtii iuviIiiIIh. 'fliv oilw raltmicn *n (h* mmt ta in 
PIr, W.)lin. TliB t«''» urihe oiDnriclor niitt* an ibowa hj tk* 
armwi. Ttu itoiiail lliiu Iti iliD tjilnal cofd. 8f^C ii to tndkaM !&• 
roiHBe (if tiiiuLHctDf lin]iul*a dona Ui* O0«il AolD Uie < 
(<uiilr«iii Uic iHMlulla. 

ganclion. aiid theuce either along ihe ramus commuuictuis (visceral branch) 
to ilifl unt4-rti>r rniii uf tbc second darutl nerve, and thus u> Ihe HpinnI cord, 
or lower down along the thorncic Hyinpaikeilu cliaiii, and lliciice by iXher 
rami com nniiii I'll iit*ii lo sonic other of the upper doraal nerve*, and ibu* 
to lh« spinal cnnl. The pulh talien by the*e vatiomolor iinpulw^ for ll>c 
Mr b in fact very Mniilar to that uf tht: ntignK'nior tibren for the hrart icf. 
FiR. 9(i) from the spiual cord up lo iho niniidiiH of Viciumnit and i« the 
lower oerviral ganglion ; hut there th'-y part company. \Vv can lhn:< tracei 
tlwoe iiDpulaes along the cerrica] svmjuithetic to the anterior root* of cvrtaia 
doiMl nerves, and through lh«ae to a particular part of tbo BPUial conl. 
vhfK we will for lh« present leave ihem. Wc may accordingly speak of 
vaaoiDotor fibres for tlu- car as pawing from tbo doraal ipinal cord to the 
ear along the track just marked out ; stimulation of iticw fibm at ihair 
origin in the spinal cord or at any part of their course (along tlie anterior 
raota of the second, third, or other upper iloreal nerves, viseemi brancbee 
of lho*e nervftv ganglion stcllatuni or upjier part of thoracic syiupatbetie 
cbain, annulus of Vieuasena, etc.) leads to constriction in the b'looavesseU 



of Um cat cl' thai nda; tand ■ection of ihne fibm at any part of tli« mme 
wnm uod* to nboluh nay prcviotitly txbtiii^ tonic ooiwtrictioti of the 
UoednsMb of tbo *ar. though tt)i« rllKt is not so coosbint or iiariliiog as 
tlwt iif rtliDakUon. 

6 167. W« nUMt now luni to another caae. In d«alin); n-ilti fliK«etion ire 
•ImU have to itudy tli« Mibmnxiltury salivary gLaiid. We may for tLe 
pCVMt ainply aay that this is a (•laudular inafs well supplied with blood- 
riaib,aad powcaJng tt double nervous supply. On the one hand it reeeiree 
flbm ftom the eervical ayinpnlhotiu. l-'i;;. Ot5 v.ei/m. (in lh« dog, in nhidi 
tlkc Hfecta which we are abotit to deacribe are bat wen, the vafcus and cervical 

rni. w. 

*«■>>■■ iTur Rtnaonittcui nr tiia BrnmixtuAav Glixd or m* Doa, vim tn KmvM *ki> 


TWiUmc^Idx ku tiNd mult (HI ■■Knliiul Ijlnf on it* tack, tint iIdcciiII IhB puti iIidwd tn Qtc 
afB*«adai Mon Ihnnuir oacfulntof Tt«r, ibeBKiuvlaet iioi kIv* Uie ciarl anuonlio] rvK- 
*««r tt> n*«Hl MnwMN*. 

»t^Hi«— lm»lltMy«l»jna. lnu>tbBdiici[—. Jml which aunolA bu bran Unl llwntb- 
MaHl (iHid and duet uo nutibuoii. aJ..!!/. Tlic Uiik'i'I tiniiicli i-rtlwMli oorvo. tl»«(*n sj. 
• fM^lattalcafw^ <*,f..rAf .rb r Thocliooli trmr>»l. I'bi (•!( (A. I", li rxxmllnc Roni Ik* 
tiM Mn«, •> (ft. r tt btcona Rin>)IiiL>d wlih Ibc tinituil i>.r., uiil ancnfard illnnclnc j«nii M 
At l> Iha lUiht alonf tlniliKt: ih* «nilliii»riuii of Ibv nirvptn nuDistiy wilh Ihr llninuil. n.l..t> 
■» (J Tim wlw I in> IT »"■>""■*'" I* "' — J-™' «— ^- a. cor "na ouiMUl krurj-. Iirn 
■bvof wMi4i, ■.•!•■ «.u«l r, ■u.p., IWB (o (be ■nlorkii luid powwlor t«n> of lb* yUnd, 
< ■■ tts Milwtot and ixMarlur Tdn* frum Uw«land, Atlllus lata r./.ttui Jugular t>Iii. r.i9iK.Tti« 
I i«(iB and (n>iF*UMU<i iniok*. g, frf, i. Tbe uppii nrrlotl aangUon. l*o bniiialic* of 
■iiK ■ ptdn (oj-t onr Ihs llulal utcrj. an dlilrlbutnl (a.ivKni.i alont tbo Iwn 
I Id Ih* aoMsm and (oU^or ronlcn» of Itivsland. 
Ha WW «a todinaw i>a dlwwllwi ukvit by iLeaEnKiiii Myulta dsrlni mztx iilaiulatkni pIU* 
nar nwuid (a IJic loaln br Um Ungual aiid dcaomd b; Ike cborda ljnii«iU. 

)*tBfaihrlic aro encJoewd in a c<>niin<iu sheath »o as to form what appean to 
Maiinclv trunk), which rea«h the gland in eoni|>aiiy with the arteries nip- 
plmgUivglMid (N.nwm. fm.). On die oth«r hand, it rcceivoi fibnv (W>ri a 
^alTBervv callnl ine chorda tympani (cA.fJ, which, springing from the 
VTWih cranial ( iWiid) nerre, crown' Uh- tympanum of the tuir (henoo the 
Mat) aitd. joining tbi^ lingual branch of the fiAh norvr. rum for «ome ilin- 
Uan m compaDy with Ihnl n" rvL-, and then ends partly on thi- tougtie, and 


TUe VASCULAR mkcuakish. 

partly in k small nerve which, leaving tlia linriMl nwre Itefore rcttchio); tht 
longucruM alnng tlie duct of the tubnudTwry gUod, mkI is lost in ihe 
ButMtaoce of the glmM) ; a small branch is also given 09" to the Bublioi;iial 

NoTc wiieii ihe clitirdu tympnai ia siniplv divided no verv rvin&rkable 
cUuiii;eti ulce place iu the bloodveesets of me gliind, but if t}ic peri|ih«ral 
eet;i>ic<il of the divided iiervi?, llinl still in counection with tli« ulaud, )» 
atiiuuliit«*l very luarkt-d tchuUs fullow. The suiall arteries <if the gluoA 
become Tcry much dilntei) and the wbole'glond becwoea Btisbed. (A»ki> 
tball ne Inttir ou tli*> gland ai the jiame time secretea aaliva conioudy, but 
thia doea not cuiicerii ua just now.) ChiiDijee in the calibre of the bloUiro- 
wIh are of cniirac nut *<> reinlily mcu in a compact glnnd a« in n iliiii pjctentled 
but if II fim- tiilit^ \>c [ilticeil in one uf tliv small veini> by which the blood 


rettirna from the gland, thv eBeotd ou iho bl(ir)ilvi>wi*lH of iftimulutin}; tbc 
cborda tym|iiiini Ikciihic very cbvicu?*. Before (ttmulation the Wood irickla 
wit in II thin nlow nin-ani of a dark rcnoua color; during atiniulation ibe 
bluod ni»h(9 out in ii rupid full streum, oilcii with a distinct pulsation and 
frc<|Ucnlty of n color which is still scnrlit and arterial in spile of the blood 
having IravcnK-d the capilluries of the glnnii ; the blood rushes so rapidly 
through the widened bloo<lveiwtels that it has not time to undergo cnrnpfetely 
that change from arteriiil to venous which normally occurs while the blood 
it travervitig the cKpillaries of the ginnd. This state of thing* may continue 
for SOBM time alter ihe sriuiulation haa ceawd, but before long the 6«w from 
the vans slaokeRs, the iHuiiiK blood liecoaiea darker and veooue, and 
eventually the circulation beftmea uonuul. 

Obviously the cborda tynipani contains Rbrea which vre war ii|>eak of aa 
" vasomotor," since stimulation »f them produces a change iu, and bring* about 
■ movenieni In the hliiuiive(«ela ; but the change produced ia of a cbaractvr 
the vm* opjMMtili; to that produced in the Moodvewivlit of the mr by simula- 
tion of the cervical sympiithelic. There stimulation of the nerve cmtued 
contmctiou of the niu«cutar fibres, constrict ton of the small arteries: here 
stimiilalion of the nerve cniist^ a widening of the arterien, which nidening 
is undoubtedly due to relaxation of the musailar tibra*. Hence we most 
distinguish b^wcen two kinds of vawniotor fibre, fibrea the rtimulation of 
which produces constriction, KOAo-eonttriclor (ibrus. and tibree the atimulalion 
of which causes the arteries to dilate, va»0'dUali>r fibres, the one kind being 
the antagonist of the other. 

The reader can hardly fail to be struck with the analogy between theae 
liro binds of vasomotor ^hres on the one hand, and the inhibitory and 
augOMntor fibrea of the heart on the other hand. The augmentor cardiac 
Hmta increase the rhythm and the forc« of the heart beats \ the vaso-oon- 
Kttiotor fibrea increase the coDtractionsof the muscular fibres of the arteries; 
the one works upon a rhythmically active tissue, the other upon a tiaiue whoM 
work is more or lea* continuous, but the etTeot is iu each case similar — an 
incieaM of the work. The uihibitnrr cardiac tibr«« slacken or Ntop th« 
rhythm of the heart and dEminish the tieat* : the vaso-dilator fibres diminish 
the previously existing coiitructinn of the muHciilur fibres of the artcrin so 
that these expand under the prewua- of the blood. 

We must uot attempt here to di*cuwi what is the exact nature of ihe pro- 
ctw by which the nenoux impulses poising down the fibres thus stop coo- 
traction and induce relaxation, but wo may wy that in ull prdhahility ibe 
proceee, whatever be its nature, is one which tnkc« pliue in the muscular 
fibre itself on the arrival of the nervous impulse, and that (hen^ is no need to 
pn-wppoM the existence of any special terminal inhibitory or dilating 
nervous mecbanism. We have repeatedly insisted that the relaxation of a 






fibrv i> a* tuuch a complex vital procns, i» u Irulir th« reeuit of 
DoUmu of iIm muHGular AubstiiDce, as llie ooiitractioii iMelf ; and 
tbwv ii A oricti tio rawoa wlir a uervuu* iiiipuNo >hoiil<l not Kuverti tlio 
liinwr u It doc* the lulter. AVl- tuay, jMrhiijw, ^i I'lirtlier aiiS M\y ilint 
rcUxatNOi need not b« cuuHd<er«() lu tbe iti«rc iiutloiiij^ of a citutrm-lina ; 
tb»t %h» actioo of dilator fibru in ool nMHwnrily Itmiie'l Ui ihc rrniuval of 
B prvvioudj cxipttuj^ cowiricliuii. We miiy iiiuigiiic n tiiuimilur tibri' lu 
—bjacl toUirnctiuool'tvo <>[i|Hitiiiig l<im» — ttiv uite vioiigntiiie. rvinxirig. or 
dOatiHI^ : th« otlicr vbortCDing, ■.■nuimcling. or ouiulrictiiig. When nviilhtr 
i» in acUoo, or «bni thv too ati; («ii]i{i(ill»it, tlio fibn it at rCHt, Deilhaf 
nlaxiDg RorcoDtnu-ti»g; nlx'u iiiieacUaluiiv, orwh«a one acts more pontes 
fullr tluui tliv othvr, itirii rrUxntioa, elougnlkiii, dilatiou. or otiivrwiae coii- 
trw^tun, sboru-uiii);. LviU'tric-tioD, u tli« mult ; wu liuvo )>rob»bly a* muctl 
riKht tu (uptww rt'ltixaltou tt> bo a iiitvasiry nntvi'eilcot of oonLriiction aa tO 
■uppMc couuacliou to be n uvccaaity uitocnJvnt of ivIaxatioD. 

( 168. Uut we rauBt ralurn to th« vaMunotor twrrm. The oerviod sjiDpa- 
tbAir (XiDtaitM vaaoconelm-tor fibres for the ear, and vk may now add for 
•tbtT rafioBtr alao of the head aod t'licc. TIiuh the brundiea of the oervtcal 
i|MtliMic. ijoinji tu the «ul>mnxillary inland of which we juat epoke (Fiff- 
n. *jtit. am.), euntsin vaeo-eonslriclor libnn for the Tewejs of Uw gland ; 
•llinuUiiun of tbeae fibres producw on the vessels of the jfland on elftcC 
exsctlT tbir opporile of that prudticed by BiimulatJDO of the ehorda tjrnipani. 
But l(> iki« paulicnlar point ire aball liave to return H'h«n we deal with the 
ylaad lu connection with dJ);ettiiou. A more importinii fact for our present 
parpOM b that the ecr\'ical evnipulheiic appenni U> ooniaiu only vii»o-4.-i>n- 
auiolor fibrea; if we put oude m exceplioiiul and doubtful the rvxult uf 
certain oheerrem who obialtied vaau dilator cdccLn in lliv nimilh and fnvc, 
v« any aay that in no re){iou lu nbich tht? libm of the crrviciil aympathctic 
•na distributed can any vavo-dilator avtion l>c observed a» the result of 
•tlinalation of the nerve at any [lart of il« course. In the chorda tynipani, 
Ml the other luind, the vuwniotor tibn^ are exchisivelr vnsudilalor fibres, 
and ihts is true both of the part of the nerve eudin;* in the Bubmaxillary 
■nd *ubtiD|[ual gland* and the mtt of tlin ending of the nerve in the tongue. 
i?(iliiulatioD of the cliorda lympani (a» far as the vosoiuolor lundiona of 
tba narre are iionccrned, lor it hoa, as we flhall »ee, other fuDciions) at any 
patftof lt> courae, frum ii» Icnviiig the facial nen-e tu its endings In the 
nogn« or gland, producee only vaso-dilator etleet». never vaso-constrictor 

Wkh many other oervee of the body tite case ia dilTerent. In the frog 
dhrliiMi of the sciaiU! aarn teada to a widening of the arteriui of the web 
«f tbt Cmx of the aane tide, and stiniulaiion of tlie peripheral end of the 
MTT* fiiscs a constriction of the vessels, which, if iht; Miinulatiou Iw strong, 
naty ba ao great that the web appears for the time licing lo Ih- deruid of 
blood. Abo ill a maromal diviHiou of tfai^ Kialic iutvc causes a Himtlar 
widnting of the small arteries of the akiu of the leg. Wheni the condilioii 
uf Um escalation can be readily examined, on, for iiutanee, in the linirloB 
Ulboftbe too. especially when these aro not pigmi'ntml, thevesscJs are seen 
to be •litalc«l and iitjecteil, ami a thennoneter placed between the loot shows 
a rise of teiii{ierature aiuouuting, it may Iw, to •vvemi degrees. If. morv- 
«>r«r. the peri|tli«nl end of the divided nerve be stimulated, the vcwels of 
the skin beootnv cvnttrictvd, the «kin growi pale, and the Iciuperature of the 
flat fclU- And very nmilar mulls are obtainctl in the fore-limb by diviuon 
tad •ufaMqacnt stimulation of tlw nerves of the brachial ]>lexus. 



The iiuunliiy of blood prtwot In ibp bloodvcaiela of the mamnal, thongh K 
niaj AODiclira^H be oburved directly, tutu rm)Uontly to be d^lcrinined indinctly. 
The (ompcrHtiirc nt' pasnivc i>triicturn> lubifCt Id cooling inllucnc**, ■u<^ll ut the 
nkin, i» tnrKply ilependcnl oii ihr Miipplv iil' bUtod ; the inotu nbunJanl the Miiipl* 
the wftnner i^i? pnrt. Ileiice. iu tl]«ae purts variutiuiis in the qiianiiiy <if blixKl 
may be inferred TrotTi Tmifttions of temperature: biil in dealing wilh more ik-iIvi^ 
Hi (ucturos there nre i>bviou»lf •ouroos of error in the imuibility of thr treatment 
adopted, ouch as the ■UmulBtion of a nerre, KiviiiK riito t'i an incrtuuc nf tcrnpert- 
lur« due tu increiuwd metaboli«m. indepwident i>f variHilooii iu blutKl-supplv. 

The <|uaD(iiy ut blood mav also be determined by Uie pktIiyimoffTttph. (o Uila 
InatTuinent a pari of the body. «u«h m the arm, is introduced iuto a cloaed cham- 
ber eilwi with Hniil, rx. gr.. a Inrge glas* tube, ihi- (ipeninK by which the arm ia 
inlroducL-d hthia securra with u ultiul cuniitcbnuc uieinhrnne. An inprtAao or 
d«crcac« of blood aeni Into the arm will lead to au iucrearie or dcicrcBM of the 
volume of the arm, and this will make ilacif fett by an increase or dimlnutiMi of 
preMUK in the Huiil of the ciosed chnrobct, whioh may be repimwed and meaa- 
urrd In the unual wiiy. Wo •hall have to iipcHk again of n luodilicntionof thla 
iiMlrumeat «'b«u w« are dealing with tile ktdiiey. 

^ far the reeults are quite like llioae obtained br division and atitnulation 
of the cervical sympalhetie, and we might infer lliut t.bu M.-iniii- ner%-e aiid 
hrachini plexui coDtain vaeK^eonsirictiir fibre* for the vectebi of the sktu of 
th<^ himl-Iioib and fore-Hmb, vnMi'dilaUir fibre« bdng abnot. But «oni^ 
tiiitra u iJi&Kiit revolt in obtninerl ; mi ntiniuliitinf; the divided acinlic nerve 
thv vcaMila of tlie fo"t an- not t-unatricttfl, but dilaluil — |>crhniionttielv iliUted. 
And this vn:«ii-diiiilor ailion is alnuttt sure to be nianili.-»l«'d when tlie nerve 
is divided, mid the pciiiihemi stump Bliranhiled Ajnu- dny» after diviiion, by 
nhich tim« comnicucing degeneration has l>egnn to interfere with the irrita- 
bilitjT of the ucrvo. For exiimple, if the sciatic be divided, nnd some days 
afterward, by which time the Hushing and increased Icmporniure of tbe foot 
foUowinji upon tbe aection bus wholly or largely passed away, the jKripheral 
Mump be atimulated with an interrupted current, a renewed Hualiiuj; and 
riae of teroperattire iit the result. We are led to conclude tliat the si-iatic 
nerve (and the aaine holds ^ood for the brachial plexus) oooiaina both \-B0o- 
oooatrictor and vaao-dilator fibres, and to interpret the varying rmilt a* dut 
to varialit'NH in the relative irritability of tbe two neu uf Hbrat. The con- 
Mriclor fibrca ap|)eur to predominnce in thuao ni-rvea, and henc« vonittrictjoo 
is th« more common nMiult of stimulation ; thv constrielor fibm also *PP*>r 
to be iDore readily alft-nled bv a tetaniMng current than the dilator nbrce. 
When the nerve after division coinmcnciv to d<«cneriite. the cnnclriptor 
libm lose their irritability earlier than tlit; dilator hurtv, so thai at n certain 
stage a stimulus, such ns the interrupted current, while it fails to atfect the 
OODStrictor fibres, readily throws into action tbe dilator fibres. The latter, 
indeed, in contract to ordinary motor nerves (§4-1), f\-tain their irritability 
after seotiou of the nerve for very many days. The result is, jxrhaps, even 
still more strikiuK if a Dteehani(»I rtimnliia, <uch as that uf " crimping " the 
nerve by rejieated Miips uith the teimon, be employed. Exposuic to a low 
temperature nj^in aeetua to deju^eas the eonstrictore more than tbe dilaioni ; 
lienoe, wbeu tbe leg is placed in ice-cold water stimulation of tbe sdatic, e\'en 
when tJie nerve lias be«n but recently divided, throws the dilator only into 
action and pniducea Hushing uf the ikXa with blood. Rhythmical Mioiuta- 
tlon, nioroovcr, of even a freshly divided nerve pmducta dilation. And 
there are other fticta which support the aauie view that the iivtatic itcrve 
(nnd bracbial plexu») ontnin^ Wh vaao-ooustriclor nnd vaao-dilator Bbrttf 
whii'h are diflcreiilly nflbclcd by diHereiil circumatani^c*. Wc may jmint 
out that tbe caae of the vagus of tbe frog is a vcr^- analogous one ; in it arc 
l>o(h canltac inhibitory (true vagus) ana cardiac augmenlor (tynipnthclic) 



ttbm. biit thi' funnier, like llit; vtw^eonHiicXor fibrtv in tbc scintic. arc 

fim)<(iuinBDl. nnJ vfivciiil nuuiDS nie raciuiretl h) altow Oto prcMDcv of Ihe 

In ll»o fplanchriio iMTre i iib'lominAl uplnnchnic) which tiipptu* fibrw to 
tlie tiliMxIufocU of wi targe a piirt of tho nliiloiitiniil vioccra, tbpra is abiiD- 
4mDl •vidvnn- of ihp preKiicc of vasn-comtriclor Hbres. but ibo prceencc uf 
TMO-ditnior fibn'c liiu uot yet been #hoiin. Division iif this nerve leads to 
■ wulroiug of tbe bloodvnwls of tlie iibiloniin&I vi*cern^»tiin illation of itie 
ncrvr In n con strict ion ; and, aa we shall we. lince tbc nnioiini of bloud- 

finib ibii* fpivenieti by lliis nerve is very large indeed, interference eillicr 
lo lJi« tine ilin<cti«n or llie uiber witb its vHBoniotor funetioiie produeea very 
rkoi nntlte, out only oii the cireulaiiuii in the abdomen, but on ibe whole 


In Dcrra jcoiog lo muadea voao dilKtor fibres preitomiiiate : indeed, in 
Umw the ^neeace of any raso-ootutrictor fibres ut all has not at pTesciil lieea 
Mtirfaetonly eaiablubMl. Wli«n a mu«cle (.'uutraclti there b alwayn an 
iBcnaaed flow nt blood Ihrou^ili tlio muacic; lliia oiny he in imrt a uvcre 
■Mchwiical reault of the diunge uf form, ilie ^liurteoiuj; atkd tliiekening of 
tbe 8bn* opeiiiag oui tbe mtnnte IiIoucIvvkwIh, hut in not wlirilly, luid prub- 
ably Dot nvtn lar;g«ly, tliim prirduct^l. A notable feature of va»onaotor 
flbiW M ibai, iu rerv iDnnr c*m« nl all «vrJilii, their action id not nflocud br 
■OmII or modcmti' d<Bc» of nrari *uc-ti ii« r<'iii]«r the niolor nervca of HtriaKa 
mwde |iowerl«». ThiJ». in a frog plaotx] niitlcr the inflnenct! of n motl«nit« 
■■iniiiH of umri, ftiinuIiUion of K nervv gi>ing to a miitcic will proditc* 
T— pmcior »0tc1« iinuccotnpiinifil ami iitioUcured by any eoDtraclion of the 
■riatvil fibm. By plncing a thin miiwrlo of a frog, auci as the mylo-liTokl, 
oiKkr tbe micnaconc, and witiching the calibre of the Kninll ariericK ano tbe 
draahuioa of the blixHi t]in»ij;h them while tbe nerve i^beinf- atimulated, the 
wUeniBg of ihv bloodvewveU aa the reault of the fltimulation mar be actually 
ofawmd. Tbia ex|)eriment appe«Ta not to aucceed Id a mauiuial ; and it hna 
bean anggeoled tliat wlivn a niniM-k- euntraeta soiue of the chemical pmilijeln 
ai tbe laMaboliam of the mmclc may. by direct action ou the minute bliHxI- 
apart from any mTviiuK ageiicv, lead to a widening uf thuae blomt- 
: tltia, however, ia doubtful. \^ ith regtird to vaxi-ciHiiilnc'tur tibrot, 
tba onlv •videnc* that thryexiot io niuitela) in that when the nvrvo of a 
nittcle It iltvidH the blooilvmvl« of the mutcic widvn, fouiewhat like blood* 
va«rk of the car aAcr division of the cervic*! ayiupnthctic. This euggcvta 
the pmonoe of vafir constrictor fibres carrying tnc Kind of influence which 
we cwlJn) Ionic, leading to an habitual laoaerste eonntriction ; it cannot, 
hamvnw, be ragarded by itself as conclusive evidonco; but we must not 
Jl BB il ibe (nalter here. 

Smakiog generally, llien, most if not all the arteries of the body are mp- 
pJiu Willi vasumoior libres niniiin^ in this or that nerve, the fibres being 
«itber Taso-MoMrictOr or vaau dilator, and Mime nerves containing one kind 
«f flbna only, some botli in varying jiropiirtion. Alinoai every nerve in the 
body, tbnvfitre, muy tie lu»k<.'d upon aa inllueueing a certain wt of bloix)- 

TOirb. M goterning a vaaeuliir area, the area heinj; large or small, and the 
|ov<fn(nmt being csehiKivcly roiutrictor or exclusively dilator, or mixed. 

TAe Orvne iff Va»o-fomitriet»r anti VatihdiMor FSirf*. 

i 189. Itoili the vaso-cou>triclor ami the va«r-dilali>r Sbrra have their 
urigin in the cvntrul nervous system, tbe «pinnl ct>rd, or the brain, but the 
I of tba two *ets apiwan lo be very differcot. 



111 lh« mnniniiil. bb far n« wf know iit jircscnl. nil ihe v-n*o<^>Mt rid rtrt 
JibrM fur tin.' whoK' Ixxly liikt^ liicir 'irigiti in t)ie miiMlf re^ii>ii of itie ttpioal' 
cord, or rather Iwivc ihiy spinal cnrcl hy llie iioivw Iwlongin^' In tLU nii<ldl« 
regioD. TiiiM in ilic iV>i Ihc vus» cinmtrifUir filtros nol onlj for tlip trunk 
but ri>r tlio limbs, iiciid, liicc, timl tail, IcKVc thi> fpinat coixi by tbe itnterior 
root« of the spinnl tiprvc§ rcnchini; from about the second doriul li> the second 
lumbnr nerve, bnlti inclusive. UuRiiini; in the cose of eneli nerve root to 
the mixed nerve trunk they ps«B hIod^ the vieceral branch, white rnoitis 
comniunicnus, to the L-haiu of Hplnnchotc Rnii|>liu lyini; in ihe ihorax utd 
abdomeD — the so-called thoradc and abdominal sympaltielic olicin (Fij;.97). 
From theee gSQclia they rea<^'b their deelination in various nuys. Thus^J 
tboee (foing to the head and neck paee upward through tbe annulus of 
Vieusaeus to the Imver cervical gatiglioti, and then<-c, as we hnvi* «eeii, up 
the cervical dyniiiaihelii;. Those for tbe abduminal vSaoera ihu* ofl* 'm bj 
■iotilar way to tht- abdomintil sphmuhiiiv iiervea, Kij;. 97, n6'/. 171/. TboMl 
dMiineil for the arm lake thdr way by thu retmrrent fihrei< (^rnv nini! cini* 
inunii-unli's) (Pig. 4S, r. v.), and so reach the nrrvcM nf the bracoiiil plesuN; 
wliilc lli(«e for the hind leg joiue in a itiinilar way ihrongh wini*- portion of J 
the nhdoininat )iym|<iilhclic be-iore they join the nerve* nf ihu ticJntic plt^xuiL-^ 
And the conslriclur fibre* of the skin ol tho trunk probiibty mtch thu ■pinnl 
ncrvw in which they nUiimitdr run in n niinitnr niaiinpr. All the vaso- 
constrictor Bhr». whatever iheir destiiinlion. Irnvc iht' spinal cord l>r the 
anterior rool« of spinal nqrvet. and then pae<iny: through the np|iro|irint« 
visceral branches, join the thoracic or nbdomtnal chaiimf spUnchnie ganglia. 
In these ganglia the fibres undert'o a remarkable change. Along the anterior 
root and along the visceral brancn they are medullated tibrcs, but long before 
tliev reach the bloodvee^ls for which they arc destined ihey become oon- 
Diedullated fibres; ihev appear to lose their inednlta in tbe »\g[em of 
uilauftiiiii- ganglia. We may add ttiai in the anterior roots am) along tbe 
viiceral branches, white rami ciuumimicantee, theie fibres are invariably of 
small diameter, not imin^ than 1.^ » to :i.6 u. 

^ 170. The courye of tb<- viu>o dilator fibru appears to bo a wholly ilifl^rciit 
one, though the delaiU have nj> Vfi been fully worked out in the caw of few- 
of tbe fibres only. It is cbieHy in ihv nirrves bflunging to ihe craiiinl aod 
ncral regions of lh<' central nervous system uiivnce, ns wc have nen, no 
vaso-conslrictor fibres are known to iwrn-. that the ononw of the vaso-dilator 
fibres has been succcsffully traced. Thus the vasodilator fibre* fiir the sub- 
maxillary gland running in the chunla tymnani may he tractvl, a* we bava 
seen, back to the facial or seventh iieri'e: and the continual ii>n oflbe chorda 
tyinpani along the lingual nerve to the tongue contains vasodilator librca 
for that organ; when the lingual is siiutulatciJ. the bloodvo»vU of the tongue 
dilate owing to the stimulaliou of tbe conjoined chorda tympani fibres. Tbe 
ramus tympanicua of tbe gloaso-pharjrogeal nerve contains vaso-dilator libr«B 
for the parotid gland, and it appears probable that the trigcniinal nerve 
oouuiiiis vn.*o-dilator fibres for the eye and nose and po<eibly fur otlier parts. 
Fu the anti-rior raoia of tbe »ec"nil and third sacral nerves run va«o-dilator 
fibrw whirb \>»s» into the wi-called ueri-i erl^tnlts, the nerves, stimulation of 
which, bv leading to a tvideiitng of the arteritis of tbe peuis brings about 
tbe en-rlion of that organ, the effevi l>eing uMisied by a simultaneuus bind- 
ranee to the venous untAow, Though vasodilator fibres are, as we have 
Been, present in tbe nervM of tbe limbu, and probably al^) in thuie of tbe 
trunk, the investigation of their several path* r» renderfti very difficult by 
the oiucumitant preeeiicc of vaso-eoiislrtclor labn-si. There are some reaaniis 
for thinking that the vaso dilator libre-* in tliiw nervev putKue a direct GOUne 
from tlie spinal cord throu<;h tlf lUitcHor sjunul roots, and thus afford a 



tnn with the coDilrirlor fibn.« of ibe nme n«rrw, whinh, at ire bare 
iBon. Mko > rmiiKblxMil niiinw.-. piiMiiti}: into the »pl»nchuic sysieni, l>ef<tre 
Ihty JMB tbv norve trunk. Our inl-irnniliuii. Iionev-Qr, U loo imfierl^i^t (o 
bUow an?' Vviy poeilivc HtmeOK^nl to be mu'le. Accepting; thU viow, how- 
*v«r, w« may say that while all the va<ri>'Coii<(riclrjr fibres, a.4 I'ur iis vic 
know, come from it iiarlii'iitar, lliiitigh consiilerable, pari of the sjiinal ruril 
•IhI pBW into ibe splaiirhiiio system uii their way to their Mveral deitiiiii- 
tioaa. ibe vaao-dilaior fibres arise from all parts of the jipinttl conl as well 
■a fr^Mn the inealulla obloo)^(a, aod puraue a mure or leu ilirecl omw to 
Ibeir (le4inKti»n. 

Kuribw. while the vaso-diluior libra, a* they leara the central ncrvnus 
antem. are. like the va*i-ci>itMri(.-tur llbriM. tint; inmlullated libr<», unlike the 
vaao-conHrietur* iher n-taiu Ibeir luvilulla for the ynuiler {Wrt of tlu'ir 
«oanv, and only Iom ii m-ar thvir lertuinatiou in the tiHiie wliow blovd- 
WHlt ibi'v Kri[)ply'. 

LaMlr, while in« riiM-con«tricl»r fibreii, a* in ih« cam nf the cervical 
■TRipalbvtic, of the ntdlDiiiinal >|iliinchuic, aui) of the ncrvni of the skin, 
ax»i] |irotMi]>ly tn nil iiwrs. utv mirinully in a ulato of moilctatv activity (ta 
Imw aa liwy mninin in i-onni-ction witb ttie oeiilral in-rvout nyslcni), llie 
Boomu aclirily maialainini: that nKHlerate coni*lriclioii which wo spoke of 
abnrv a« "toiic," the vavodilntim nppear to fioaiMi no such continued 
activity. i>ccttun of vaR»coiisi riclor hbr«-« lead* to loss of tone, diminutinn 
of cimrtrictioo, lA»ting, as we shall eoo. for some coniirleruble time: but 
aecliun of vaso dtlaion, nccordiu; at all events to must observeni. doe* not 
iimti in aDalot;ouD eonslrictioii or iliniiniilinn of dilation ; all that U obierved 
ia a tnasieoi increase of dilation due |tfub,tbly to the section acting as a 
tnuatnil stimulus tn the nerve at the plscv of section. But before we study 
tb* uaa made by the ceiiiral uen'ou^ syitem nf va»imotor ncrvt^ii, it will be 
bcac to cnn«ider briefly some teaturea of 

Ci 171. A <rery Utile coiuideration will show that vasomotor action is a 
■ Inpoftant factor in tbe circulation. In the lirst place the whole flow 
bloiNl in the body is nflnptGd to unil governed by what ire may call the 
fiMH-al iotu of the arteries of the body at large. In a aamal oooditiua 
of iIm budy a very ^*T\fe Dumber of tlic minute arteries of the bmly are in 
a state of toaie, i. «., of modwate, coiilrii<.-tion, and it \a iht narroniug due to 
thia eontraolioti which form* n lar^e item of that peripheral raei«tanoe which 
mm bave seen to be one of the k<'c^<» factors of blood -preasure. Tbe Donnal 
Munl b!(Kid-i)rui»ure, and, ttiert-fore, (he normal flow of Mood is in fact 
r Smodent on tbe " general lone" of the miuute arteriea. 
fe In tbe SKcnd p)ac« local vaitotnoior chauKea in the cundition of the minuta 
V sileriea. changa, i. «.,of any particular voneular urea, have very decided 
fflccts on the carviilation. Th«Ae changes, thouj^h lut-ul theuutelves, may 
bave HiecU which arc both local and ^neral. as the fuUowiug consideratiotu 
will elmw : 

Let IIS suppwr that tbe artery .4 i« in a condition of normal tone, is mid- 
way between psirvme conrtrielion and dilation. The tlow thr>Hii(b A is 
dm I mil lid by ilte rtvistanci' in A, and in the voseulur tract which it luji- 
plios. In relation to the miain iirienal preuiire, whicbaznin U dependent on 
tbe way in whit.-h the hi-arl in bentimc and on the poriphenil r<t*i»tanoe of 
■11 tbe small arteriet and capillarii'v, A included. If, while the heart and 
tbe rwt of tbe arteries remain unchanged, .1 bo const rtcted, tbe peripheral 

The ^«U of t'oMiiHoUtr Attioiu. 



Tn>!»tunr<' in .l.will nirri-ii:>r, mxl tbiti inrraiJN- 'if rtnttaDM Will Imd to kU 
iiicnni'c of lln- gcm-nil rirlcriiil )>r(-.'<i'urc. Sitiw. nt w« h«T« seen, § 119, U 
!r iirkTiiil |>ri.'N>iin- wliii;)i i% ilic imnicilliiti? cmwc of ihe (low from Xhv unprk-e 
to llic vrin*, thi» incrcnsc nf nricrial [irwmrc will lend to drive piore lUood 
from llic nrliTk-» inin th<f vtiiw, The c<>tistricUni] of A, hotrevcr, bv in- 
crcaciug l.hc r»iiiliint-<\ oji|)')Ki' nny increase of the flow through A iUvlf, in 
ftct will mitkc the tiov> through .4 lew than bcibre. The whole increase of 
difchnrgc from Ihr nrlcriul into tbt> venous FViilctii will take place through 
tbc iirtcrics in which the rreistance rcmaioe udl' hanged, tbut is, througll 
channels other thun A. Thus, ns lh« resiill of the constriction of any artery 
there occur (1) diminished flow through the arleiy itself, {1i increased gen- 
eral arterial preeeure, leading to (^) increased flow'tbri>ugh the other arteries. 
If, oo the other baud, A be dilated, while the heart and other nneries remain 
unchanged, the peripheral resistance in A is diniint^bed. Thin leads to « 
lowering of the general arterial preasiire. which in luro lends to drive leaa 
blood from the arteries into the veins. The ditaiion of .1, however, by 
diniiniBhiug the resiaiaucu, jjerinils. even «iili the lowt-red prei^ure. mors 
blood to ])ai« through A itself than before. Hence the dlniini^biMJ flow lelU 
ail the mure on the reiit of the flrteritrs in whirli iht- ret<i«tance rcniiiim 
unchanged. Thus, aa the ivkuU of the dilation uf any nrtvry. tliorc mu-ur 
(1) inert-used flow uf blood through thi' iirliTv it>elf, (li) diniiui»hi-d gciiemi 
prwiiure, and (3) diiuiniiihed IIoir through Ihr ni'ier urliritw. Whi'ro the 
artery ihun cunitiricted or dilated is --mall, iho Wal cllecl, tin- diminution or 
incnMe of tluw through itself, is much nu>rit jmirltrd tlmn the general cffi.t'lf, 
the diangu in blond -premurc and the tlow through other nrtcrici<. Wbcn, 
howdver, the area, ihi; arteries of n'bich arc alfcctcd, i* large, the genera] 
eflcclit arc very striking. Thus if wbilr n tniniie •4' ibc blood- prra* lire it 
being lukin by nienns of u roiinomclvr connected with the carotid artery, 
ifafl abdominnl splanchnic nerves be divided, n conspicuous but steady tall 
of prenure is obeerved, very similar to but more marked than that which is 
Men in Fig. ^if. The section of the ubdoniinul splanchnic nerves causea 
the mesenteric and other abdominal tirteries to dilate, and these being very 
nuuerouH, a larse amount of peripheral resistance Is taken away, and lli« 
blood preeeure JallK accordingly; a large increase of flow into the portal 
veiiis takt-a jilace, and the supply of blood lo the face, arms, luid legs ia pro* 
portioniiUy diminiBhed. It will be observed that the dilation of the artrriea 
Is not insianisneouH but somewhal gradual, as shown by the pretaiire sinking 
not abniplly hut viith a gentle curve. 

The general etlecls <iu nlmid-pressuie by vawimotor rhaDge» are ki marked 
that the manometer may be used to detect vasomotor action*. Thus, if the 
stimulation of a narticular nerve or any uther o|K-niiion leads to a marked 
rite of the mean iilood-preft^ure, uniicrompiinii-d by any changes in the he«n* 
beat, we may infer that constriction bat> taken place in the arteriec of tKxnc 
Conriderable vain'ular nrt-ii; and similarly, if the eHi-ct be a fall of blood- 
prewure, we may infi-r ihiit constriction him gtve:i nay to dilution. 

Vatomolor funtiieit of the Ventral Jicniwu Sutton, 

^ ITS. The central nervous Kysteni, to which we have i.niced the vasomotor 
OCTves, makes use of theeo nerves to regulate the flow of blood through tbe 
Tarii>us organs and parts of the body ; by ibe loeal elfecta thus produced il 
artiitB or otherwise influences the functional aetiviiv of this or that tisane ; by 
tbenueral eflfeota it secures the well-being of the body. 

Tm use of the vaeo-dilatur nerves, which is wore flm{ile tliou thai of the 


nwMUlriclofs «nw it ii|>pi-iLr» not in )i« c»mplt<-ntc<l I>r (lie |>r»jeiice of 
htUtiwI Utaw infliMiK-cs. in friMiiiitilly (.-unfliiii-umis bh pAit of n reilex act. 
HiB^whi'ii ISkh) is plneeH in lliif miHilti. atf«rciit itiiiKiliM?^, (*euorat«') in thai 
■Kn* of taste, give rite iii tW cniitrnl nervous system ta eflerent iinpiiUM, j 
■tich dM<wn<l tne chorAn iytD|Miii and other nerves tu the salivary i^landfl^ij 
ml, hr diluliii;; tlie tilnoctveescls, secure & copious How of blood ihrnuKh the ' 
|Iiadt, nhile, na vre sli*)! see Uler on. they excite ibeni to iH>r'rele. Tlw 
mlnof thii reflex actioo njipears to lie in tho iiieiliilU oblootcata, and tiiiijr 
b throVD into acliviiy not only by irupulites reaching it aliin^ the s|)ec-i6c 
w&imot Uste, but nbo by imputsoi puasiiit* iiliinK other chumeU: thiu, 
■DMkni ftartad tn t)>e hruio by the Bitrht of Ibod or otherwUe may cive riw! 
k iwfiiliM pttninit dowD kIohk the oentral aurvou* Byfltcm ilMlf t^ thai 
■daAi oblangHta. or eveata in the atomach nuy send iranutnes u|> the vagiNiJ 
Mr*«,orUiniulBiion of Olio kind or another may Miid impti1^4±i itp nlmoftl 
UTMBtiwit nerve, nnd the^^ various iiupuUoii n^ai-hin^ the mi-ilullii iaiiy,hfl 
MnMtkwi, thmvrinto aclivitv thvrttiiii-dilaior filinaorilicvhunla tyinpunlj 
nd (titer Kualngou* nervesi, »nil bring ubnui a l1iiT>hin);'if thrr aalivary gluudi, 
«hilt It tho (Uiie lime ihry ntUM- ibu ^Innds In KWreiv. 

Ibe irMu^ilator fibr<» i»i' the nervi crigenirti may !>« throwii into aclUlt^ 
hianitsr reflex way. the c^nlrv in this cn*i' l>cing ptac^l in thu himbiir or 
Inrwilorvl txirtion i>fth).< spinal wrd. though it is wwily thrown into luitivitj 
h iiiipuliMw d«Kending donrn the spinal i;i>ril from the brain; that such • 
nwie doce cxit>i. in shown by th<^ fact that wh«i in a dog the spinal cord it 
ONDfiliiely divided in ihe doreid rvjjioii, erection of tho penis may remlily bft 
t(M^ about hy Blimiilntion uf the sentient surftces. And otlior instancw 
■ijglit be ijuoted in which rnsi>^ilaiur fibres appear to be connected with a 
'tntn " atMin after their entrance into the nervous ayBiem. 

If. a* Mcm« pnilKible {$ in' I. the bloodveMftls of a tnuacle dilate hy vaan- 
maUtr action whenever the muscle U thrown into conlraeiton, either in a 
ftSex or voluntary movcniful, thr va»>-dilatur Bbret of the miiitcle would 
(MB to bo thrown into action by imjiiilM^ arising in the Npiiiiil cord not Air 
ftom the origin of the 'inlinary motor impnlxtt, and accompiuiying thuM 
Botiir IfnpalM along Uie motor avrre. 

i ITS. TheotMoftbe vnAo-conMrietorlibreallMfnewliaiinoreoninpliiMtm), 
(D account of tile exiKtrncc of tonic influcmcea; sincis the sam«! tilirra may, on 
iWitnn hand, by an incrtwMT in the imnulM* passing along them, bo tlie 
■wan* of ronftri<.-t>oD, and, on tlic other hand, by tho n'moval or diminution 
of the tonir inllucncw passing along them, be tJw incunK of dilation. We 
ka** alrvady trau.-<) all the vaso-canstrictor lihrM from the middle region of 
the spinal cord to the splanchnic system in the thorax and abdomen, from 
■beacr tbey {was (i) by the abdominal eplnnchuic and bv ibe hypogastrie 
a W TM to the vsMCra of the abdomen and pulvis (oonceniing the vaaumotor 
■■rvea of Ibe thoracic vi»oera mc know at present very little): (2) by th« 
wrvicnl sympnlhelic or cervical 'Splanchnic, a^ it might be called, to the skin 
id* I he liead and neck, the •alivary ^lauda and mouth, the eyee and other 
|Mna,and probably tbe brain, including ila membranes: \'-i) by the brachial 
md •ctniic pk'xuaea to the skin