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1 



I 
I 

If 



HUMAN PHYSIOLOGY, 



STATICAL AND DYNAMICAL; 



OK. 



THE CONDITIONS AND COURSE 



or THE 



LIFE OF MAN. 



JOHN WILLIAM DRAPER, M.D., LLD., 

rEOFESSOR OT CHBXI8TST AHD FSTSIftLOaT IK THE UIOTXBSnT OV KKW TOHK; 

ACTBOB OP A " BI8TOBT OP TBK mTBLLECTUAL DETILOFMEKT OP BtmOPE," 

"TUOnOBTS OX TBE PUTDKB CIVIL FOUCT OP AaCEHIGA," ETO.> ETC. 



WITH mSABLT 800 WOOD EXOBATIirQS. 



■ ETBMTU EDITIOX. 



NEW YORK: 
HABPEE & BROTHERS, PUBLISHERS. 

PBAVELIH BQUABE. 

1878. 
'1f 



&itdred» according to Act of Coogress, in the jeor one thotuand eight hondred and 
HARPER * 'fiitOTHtiAs,.: 

in the Clerk's Office of the District Court of the Southern District of New York. 






PBEFACE TO THE SEVENTH EDITION. 



AsoTHEn edition of this work being required, I take the opportunity 
of returning my thanks to the medical profession and the public for 
their continued favor. 

A recent and thorough examination of it enables mc to say that I be- 
lieve it will be found to present the Science of Physiology in its most 
modern form. 

It is intended to give an exposition of the Physiology of Man, con- 
sidered as on individual, and may be looked upon in that respect as a 
work complete in itsel£ 

But man is also a member of society, auJ, as has been remarked in 
previous editions. History is in truth only a branch of Physiology. 
This is the point of view from which I have regarded the subject in ray 
"History of the Intellectual Development of Europe," a work which, 
taken together with this, is Intended as a treatise on the entire range of 
human relations, individual and social. 

The remarkable favor with which that portion of the work has also 
been received, both in America and Kurope, several editions, transla- 
tioiw, and reprints having been called for in the course of a few months, 
satisfies me that tlio views here indicated meet with approval. 

For the cncouragemcat so shown to these works I again return my 
i^inccre thanks. 

.V<» York, 186A. 



7^34- 



PREFACE TO THE SECOND EDITION. 



Two 



aco the first edition of thig work 



was publislic'l, Sinco 
tl:&t time several thousand copies have been disjxised of; it lius been iii- 
trodnccd as a text-book in many of our medical schools, and 1ms been 
l^cry favorably received by the profession and the public. 

I have t}icTcforc felt it ncccssory to submit it to a careful examination, 
for the purpose of removing any errors it may contain, and improving it 
ns far as its present fonn admits. Tlio revision it has undergone will, I 
Iiopc, make it worthy of the continued patronage of those wlio have hith- 
erto shown it so much encouragement. 

In these corrections I liavc availed myself of many of tlio suggestions 
made in various reviews of the original work, and take this occasion to 
express my thanks for the consideration shown toward it botli in Amer- 
ica and Europe. No one knew better than myself how numerous were 
imperfections. The manner in which they liave been overlooked has 

red to convince me that those who were judges of the science, and 
could deal authoritatively witii it, were disposed to encourage any nt- 
tctnpt at its improvement, even though that attempt was mailed by 
many conspicuous shortcomings. 

For doubtless they saw that this book aimed at much more than was 
directly expressed upon its pages. To treat Ph^'siology as a branch of 
Pliysical Science ; to exclude from it all purely speculative doctrines and 
ideas, tlio relics of a philosophy (if such it can bo called) which flourislicd 
in the Middle Ages, though now fast dying out, and from which the more 
advanced subjects of liuman knowledge, such as Astronomy and Ciiem- 
istry, have long ago made themselves free — to do this, amounts, in reality, 
to a reorganization and reconstruction: a task of extreme dllBcullVt and 
for complete success demanding the conjoint labors of many philosophers 
and many physicians. 

At the beat, therefore, sucli an attempt, embracing tlic whole science, 
made by a single individual, mnst needs Ixj unsatisfactory, if any thing 
like a rigorous criticism bo appUcd. And yet it may be truly said that 
tiie interest of the medical profession at the present lirnc requires that 
EQch encouragement as this work lias received should bo extended to 
every ondortaking of the kind. I hope that the success which has in 



V] 



PBEFACE. 



this manner atlendctl my labors may prove an cnconragemcnt to othors 
to devote themselves with hotter results to a similar task. 

To physicians I would carncslly address myself, iu the hope of ob- 
taining ihcir continued aid and hearty patronage for every such attempt. 
I would ask them why it is that we never bear of empiricism in Natural 
Philosopliyi Kngiueering, Astronomy ? Is it not because the principles 
upon which those subjects rest have ceased to be speculative, and arc 
restricted to the demonstrative, the experimental, the practical? In 
Philosophy, sects only arise wlulc principles ore uncertain ; in 5Icdicinc. 
the quack only exists because there is a doubt. And considering the 
condition to whidi the medical prot'easion in our times lias come, consid- 
ering its decline in social estimation, and its shortcomings even in its 
own judgment — is it not the duty of every physician to inquii-c into the 
causes of sucli a state ? 

If a watch is (o be mended, or a steam-engine repaired, do wc not ap- 
ply the principles of common sense to the ease ? Who ever heard of sects 
among watchmakers, or quacks among enguiccrs? If we will ojdy apply 
ourselves in a riglit spirit to its study, thcro is nothing more mysterious 
or incomprehensible in a living organism than there is in such mcclianical 
contrivances. Tlicre is nothing in the structure of man which the intel- 
lect of man can not understand. It is this, indeed, which constitutes his 
cliief glory, and makes ]iim a worthy representative of the wisdom and 
power of his Crcalor. 

As in any mechanical contrivance, so in ourselves, imperfections and 
disarrangements can only be repaired by a knowledge of the conslruction 
of the parts, and their mamtcr of working. The practice of Medicine 
must rest on an exact Anatomy and a sound I'hysiology. As soon as 
it is brought to this, empiricism will disap^xjar of itself; it will need no 
legal enactments, no ethical codes for Its destruction. And for this rea- 
son, if there were no others, it is the bouudcu duty of every physician to 
encourage to the utmost within his own spliere of influence every attempt 
to realize such a state of things. Tlic encouragement which has been 
given to this book I regard as a token that these principles ore profound- 
ly recognized by the medical profession of our country. 

To students of Medicine I may be permitted, on this occasion, to say 
a few words. It was chiefly with the hope of influencing them, and 
guiding them into the paths of sclcntilic Pliysiology, that I was first in- 
duced to write this book. I would Impress on them the importance of 
cultivating habits of thought arising from the exact and practical sci- 
ences. A great revolution is iini>cnding over the profession to which 
they have devoted themselves. If they design lo take a leading posi- 
tion, not merely following It as an industrial pursuit, but regarding it as 
one of the most dignified and noble of human occupations, they must 



A 



PBEFACK. 



vu 



I 






prepare themselves in a manner consUfent with the nio<lc3 of thought 
that must pre\*aii in the times now fjuickl/ approaching. It may be too 
mach for us to expect that our contein]>orarics, who have been educated 
in the ideas of the past, shoukl unlearn so much of what they have learn- 
ed, should In so many things begin their studies again ; but we may de- 
maud a right preparation from tliose wlio are only now commencing, 
Ta offering to tliem this book» I do not present an untried work. It is 
the result of an exj>cricncc in tcacliing for many years, an attempt to set 
£arlh in plain language tfie great features of the science, aiid to give in 
sufficient detail a representation of the present state of Physiolog)'. For 
the purpose of facilitating its study, I have di\*idcd the whole subject 
into two branches, Statical and Uynamical, The expediency of tiiis has 
been impressed upon my attention hy the necessity of conforming the 
coarse of lectures of which these pages are an abstract, to the wants of 
a medical class. The physician ia chieHy concerned witli the conditions 
of life — tho organic functions, as digestion, respiration, accretion^ etc. 
The doctrines of development and the career of an organic fonn arc of 
less pressing interest ; but it was very soon found that other advantages 
TCTo derived from this subdivision, as might have been expected from its 
conformity to tlic usages of writers on other branches of Pliysical Science. 

To llic general reader I may remark that 1 have endeavored to carry 
oat in the ibllowing pages the spirit of what is contained in the preced- 
ing paragraphs. I have devoted more tlmn twenty years not merely to 
the study, but also to the experimental determination of physiological 
(piestions, of which only a summary could Jicre be offered. It was not 
jK>5siblc to give my own results more In detail In a formal text-hook on 
the entire science, bat it may not perhaps be improper here to say that 
opiniona sometimes delivered in a few lines have cost me many days, or 
even WTckfi, of expensive and laborious experiment. 

Among tho contemporary works I have used as authorities arc Dr. 
Carpentered dlficrcnt treatises, Todd and Bowman's Physiological Anat- 
omy, and Kirke's and Pagct's 1 land-hook. As respects monographs, tlie 
langnago of the autliors themselves has been employed wherever it was 
possible A list of \vood-cuts is annexed, in which reference is given to 
the sources from which those not original have teen derived. In tlio 
explanation of these engravings tlio description used is that of tho ftu- 
tbora themselves in most cases, and it is incorporated In tlic text, as, 
for instance, in Book I., Chapter XVII., in which, the engravings being 
from the \eurology of Leveill6 and Hirschfield, the accompany- 
iriptions arc merely translations from tlie French ; or, again, in 
Book II,, Chapter VII.. in I>r. Prichard's statements of tho methods ot 
examining the skulk With res]>cct to the orifpnal engravings, it will be 
many hare hocn obtained by tJie aid of microscopic photo^ 




Tin PBEFACE. 

nphj, the process having been so far improved by me as to be made very 
available for these uses. For several of the specimens from which pho- 
tographs have been taken I «m indebted to Mr. Abbott. 

In this work I have therefore endeavored to treat of man according to 
the methods accepted in Physical Science, but still of man as an individ- 
ual only. Physiology, however, in its most general acceptation, has an- 
other department connected with problems of the highest interest. ]^Ian 
must be studied not merely in the individual, but also in the race. 
There is an analogy between his advance from infancy through child- 
hood, youth, manhood, to old age, and his progress through the stages of 
dvilization. In the whole range of human study there are no topics of 
greater importance, or more profound, than those dealt with in this sec- 
ond department or division. It is abo capable of being treated in the 
same spirit and upon the same principles as the first. I have nearly 
completed a volume, which will serve as a companion to this, in which 
in that manner the subject is discussed, and the laws which preside over 
the career of nations established, and would bespeak for it the considera- 
tion of the reader. 

John W. Deapei*. 

Umperniy, iVew York^ July Isl, 1658. 



CONTENTS. 



BOOK L 

STATICAL PHYSIOLOGY. 

CONDITIONS OF LIFE. 

CHAPTER I. 

OwdWnw (^ Li/e.^'NatKn andSoureea of S*^Mances n^lied to th« BoJg.'— Annual Qtiantities 
rtftimL—Ta/Ue ^ Fhgaioiogitxd Standard. — ^^itjma£i do mot ereoM, tint tntntjorm .'iuLtlan- 
tgt.j—Pn>fiKrtieM tutd QmaHHtM of Afaitgrt neeirtd hy lig System.— Pn^Krtiu and t^anliltM 
e/ those it rt^ore*. — Ueat qf the Body arifes/rrfm Cvmbaatum.— Coofiitfj Agnrif* in an An- 
imal. — A«r*JW»qr of lUpuirtt ia the. Hl/Miem. — Phynait Anpect of Man. — Tkc HohI. — TSe Vital 
' ■" ' 'u — Inyxtrttmtx <if Physical Seienoa to Pht^tioti^ Paga 

CHAPTER II. 
OF FOOD. 

TV mOmaJ Svidit-itioiu of PSytiotogy.—Of Food : ita Sottrtta and Ciaanjkalim — ito Value oof 
ttsgt t he r deprndail on itt Ormponlioit. — Of M\lk: its Ornipotition^ tud Um of itx WiUtr, 
Om^ SuffOTt BtUtrr^ (tnd SaitM, — Varitttious in the Compotition of Miik. — Qf Brfui. — Cff 
^ D^U. — Of the tmbryonie Food of IXrdx. — yutritum of canirorvus and herbivoronm 

f^Ammai*. — Foodfrrmedby PiamtM and deHroyed by Animals. — Uta qfwixed Food and Otok' 
iitj.-~Abtol»ttAm(miitofFood Stf 

CHAPTER IIL 

OF DIGESTION. 

nsttrc-u-ixnco on nt«-TooexeTK; dioestiox. 

JKttn ^ DigutioL^Ths Mwtth, TtxA, StomacA.— TV S(t^vry Glfmdt.—DiJTrrent Kinds of 
SaStn — Proftertie* of mirtd Saltra : */« Quuntity, ChttifttmlilM, aad Funrttoms. — Rttation of 
UmSaBvary Glanda and KUttmyM. — Tht diyratirv Trnrt. — The StoinaeM, — Ci'ruttric Jtaae. — 
OryoHiiJor itM Preparation. — Afanmfr ofprodunrnj C^yjne. — Injhaec of th» Ntrvts. — Art]f%- 
Hal t>i0t»lion. — }*r^>araiioH and Propfrtiet ofPfjtsin. — IVyionai trndfinethnat IMri/iion* of 
lAtf StmmaeA inAnimal^ and in Man. — Ohject ofSlomnrA IHgrxtion. — Prptona. — Use of Salt. 
— JjiyvtibilityofvarioaaArtickavfFooii 40 

CHAPTER IV. 

OF CALORIFACIENT Oil INTESTINAL DIGESTION. 

tJ[iifftJiiion. — Strw^mrf of the fntrstine. — fiiiftstiit Fhmdt ^ tht /ulfstine. — 
TtsicK.— 7)ltf Kntnic Jwx. — Jto't of Lieitrrhihn, — Secretion of /Vyer'* 
dmcU. — Bile. — Ijigtstion of tin Carbohytbrttf* and llydrocarlotu. — Propcrtirji ami Vari*- 
iSm (tflMTiic AriiL — Doctrinr. if tht Effects ofAddtty aad AikaSitity of tht Di<ft»tivr Jmres, 
— IBmtmiiom of Intestinal IMytationffom the making of Wine. — Afai-iny of Bread. — Injtvenco 
ttfUtat over Fermtnts. — O/tipariMm of Gastric attd InteMtiiuU IMgtation. — Chartffes oftJk Ji^ 
tm^mt QmS€nt*.~-ne Faralltesidues , OT 



OONTEKTS. 



CHAPTER V. 

OP ABSORPTION. 
DoubU yietJionUm for Ahmjrption. — The Larteals and Tetiw. — Lacteal Absorption. — Dacrip- 
turn of a ViUu». — Analogic* in Plants. — Introduction of Fat hy the Villi. — TTie Oiyle. — 
Cauies of the Flow of C^yle. — IntermaBate Chcmge* on its Passage to the Bhod. — Action of 
Payer's Bodies. — Lymphatic Absorption. — Nature of Lymph. — Stntctvre of the Lymphatic 
System. — Comparison of Chyle^ Lymph, and Sermn. • — Function of the Lymphatic iSystem.-" 
production of Fibrin. — Cutaneous Absorption. — Causes of the Flow of Lymph. — Apparent •e- 
kcting poicer of the Absorbents. — Comtection of the Laeteals and Lymphatics mth the Locomo- 
tive and Respiratory Meduxniam Page 84 

CHAPTER VL 

ABSORPTION BY TUE BLOOD-VESSELS. 
Pro^ <f Absorption ty the Blood CapiSariet. — Ocatrs as a physical Necessity. — Nature of Cap- 
illary Attraction. — Its Hienomena in the Rise and BepresMon of Uquids. — Conditions for 
producing a Flouj in a Capillary 7W6e. — Passage of Ziepud* through minute Pores. — Generai 
PrtposiiioHS respecting Cap^ary Attraction. — Endosmosts and Exosmosis. — Jltey depend on 
Cc^nllary AttraeHon. — Force against which these Movements may take place.-~Illustrations of 
Miecting Power. — General llew of the entire Function of Absorption, hctealand venous.... 102 

CHAPTER VII. 
OF THE BLOOD. 
7^ Offices and Relation tf Blood in die System. — TTie Plasma and Cells. — General Properties 
and Composition tfthe Blood. — Qftantity in the Body. — Coagulation. — Blood-cells. — Their suC' 
eessire Forms. — Imperfect CelL — Htematin: its J Properties. — Nut^ter of Blood-cells. — Plas- 
pia : its Con^fOsUion, and Variations of its Ingredients. — AB/umen, /i&n'ii, Fat, Sugar. — iGn~ 
eral Irvp-edients of the Cells and Plasma compared. — Gases of the Blood. — Changes ocaaring 
daring the Circulation. — General Functions of the differeai Ii^redients if the Blood. — Introduc- 
tion of Orygen by the Cells. — Their transient Duration Ill 

CHAPTER Vm. 

OP THE CIRCULATION OF THE BLOOD. 
The Heart as a Machine. — Inadequacy of Harvey's doctrine of the (Xrculation. — Physical Prin- 
ciple of the Circulation ; applied in the ease of a Nucleated CeU, Pervious Tissue, Motion of 
Sop and of Blood. — Dependence ff the Circulation on Respiration. — Forms of Circulation ; 
Systemic, Pulmonaty, PortaL — Description of the Heart ; its Movements. — Their Force, Num~ 
ber, and Value. — Sounds of the Heart. — Cause of its Contractions. — Description of the Arte- 
ries, Capillaries, Veins. — Ei^ilanation of the Circulation of the Blood. — Facts tujymrting it. — 
The I u^st Breath 129 

CHAPTER EC 
OF RESPIRATION. 
Respiration introduces and removes aerial Substances. — Coalescence of Re^ratory and Urinary 
Organs in Fishes. — Physical and chemical Conditions of ResjAration.^-Interstitial Movements 
<lf Solids, liquids, and Gases. — Condition of EquiBhrvtm in the Diffusion tf Gases. — Can- 
denting Action of Metnbranes. — Forms of Respiratory Mechanism. — The Ijatgs <f Man.^~ 
Three Stages ia the Introduction of Air: Atmospheric Pressure, Diffusion of Gases, and 
Condensation by Membranes. — Exchange of Carbonic Add for Orygea. — Divisions of the Con- 
tents of the Lungs. — Variations in the earpired Air. — Removed of Water. — Effect qfirrespira- 
ble Gases. — Experiments ofBegnauU and Retsel. — Nervous Injhience amcemed in Re^tiration. 
— Results ofRe^nration 149 



Kwn, 



XI 



CHAPTER X. 
OP ANlMAt HEAT. 

i\t rl K^ m t i(m o/Or^atae Forms in tJlitnmi Varinl'tons nf Tftnprmlrtre. — AftfJianiKtn for rataiter- 
iabaeijfy tkne Variationt. — JJoKlcfnnait of' Unit t« PlanU at lienmtMlItM and /frjlwtMxwr, 
— A» Cimse it Oxidution, — Comtetiatt of Respiration and Ilntt. — Tem}>eratvn of Miui. — IHm 
/ticrr ^f Ilexiiittmce. — TTfte dtunut/ I'luiatiiuui i^' Ileal, — Conpcttion ly" thesf Variation* wcitk 
me PteritMiiritits. — Anmtal VnriaiMug of Utul. — Control uv«r thtm b^ Food, Clothing, ami 
6«r. — Source of' Animat lltai. — Kffif<t of Voria^inx in %ht Food and in the mfiirrd Me- 
, both at rtafKctM its yature awl liart/'actioH. — Ilybcmatiim. — Starvattm. — Artyfiiiailio- 
Jtetion of Tftuprruturt l>y Blood- Uttiaif. — /'rina/tJet of Jteduetion of Ttwfxraturt. — liadiO' 
•iw. — CoHiacL — Evoforaiion. — TUir Balance tcith the HeattMg ProasM*. — ZcW Varia- 
tioiu t/iminated by the Circulation. — CoHlnl by tAtt AVn-mu fyyjttftn. — ftg phyaml Xatiarr. — 
AUntrvpifm of Organic Bodiet... l*»ffb 176 

CHAPTEK XI. 

OP SECRETION. 

BCSOCfi, VCCOC8, AXD DEPATIC SECaSTIOMft. 

tJ^fKi 1^ Sfrrrtion. — Type of aerretin^ Mtrhnnism, — Fdtratitm ami CtB Action. — Qf Strata 
JUmfrrttnea and tkeir HeerHiont. — OfMuctMui AJembratteM and Ihtar Secretions. — Ofilfpnttc Sc' 
tn^OM. — Tha Iavct! Us Devc^pmtnt and Structure. — Sourct, Quantity, Comyorntion, i'tts, 
mad Flom oftht BiU. — EnatOKA ofbiBary Jnijrtxiicnts in tht Blond, — Proihtrtion ifSuytir and 
Fat in tAe Liver. — Changes nf tAe Blvod-cella in it. — General Summary (f tMt four f aid Anion 
oftltr [akct: it produat* Stuftr and Fat, tlisniuates JUie, in the Stat of the Jutal Jkttnu-tiuft 
<f oiti Ulood-fxUt^ andoftht Cotnpltiion ijfiiew Ones. — Qf the dttcxtesa Glaads. — ThSpJtai: 

fiuFrntaioiu : 189 

CUAPTEB XII. 

OP EXCRETION. 
THE nUXB, UILK, AXn CttTAirSODS KXCBGTrOXS. 
SrerMuNi and Eirretion. 

Qflh* Kiiinry: its Stmelurt and Fitttctiotti.— Thf Mulfnglitan Circulation. — The Crint : its fn- 
grtdimtr, their Variations and .*yourrtji. — Abnormal Substances in it. — 7^ IVatrr tmil Sail* 
fxmit by Fi/tratian. — the CiMs rrmarf vmisidistd BoiSes.'— Manner of Jltmoval of tlte Li'f>aU 
fnm tht Jlalfiiifhttm Sac. 
Of (k Mammary Gland: its StrarJurt. — Cohstrwa and JTtUc.—Iagttdients of Milk and t&eif 
VariutiiMM. — Jn/laenrt of Diet. — /ffftwry into the Origin if (he IngrtdimU of 0» Milk, itg Fat^ 
, Sails, .'^a^r. — Manner of Action of the. Gland hy Stnmtuge. 
|2ttn. — Slrvrtnrr of itn Fpulerma and Dtrma. — .SMloriftirous and Sihaeeeus GlantU. — 
-Hair. — fngralientM of Pcrnftiralion. — Eshaitition: its Amount. — OMisa of' ihr Vari- 
«tii Aeliaii of the Skvt. — !u Double Action.— Absorjitioa by the SIdn. — General Summury if 
file CUmbom FmcHons 213 



CHAPTEB Xm. 

OF DECAY AMD NUTHITION. 
Lorn of Wtiyht in Stiwation.—fntertlitial Dtnth.— Effect of A Botrojtiam, 
i'utrition: jYulnnan ybr lirpair and Nutrition fur BaiutdeliNg, itiustrattd in the cases (f Fai 
mul Bone respeetictly. 
Of Fat: Its Pee»harilies, mode* of Ocaarnnet, and Origin. — Inqwy tehUhtr Animals evfrform 
Fat — Artijieial Prvdurtion tfit. — Auiimls both colket it and aait it. — AcaunuhjtifM of it 
tipuuti yitrogeniseft Tissue. — Conditions of tt*r Fattening of Animals. — Summary of tht 
, DrjMisnt, ami manner of Hcmotat ^ Fat.— It* partial Osidatioiu.— Summary tf Its 
-yUfogamad Nutrition, 




Xll 



CONTENTS. 



QTAnm.' Tfu Shliim,---Stnictan amd CXemioil Qimpontian nf Btme. — S(mrta ttfiu Com- 
«CilHaiC«.— THe /Vkhm of Ov^fioOtiam.—Exptrmtmta on tkt Gnneth <>f B<»it,~lnflamot ^ 
PkjmealAymU on JJeetlepmaU and ytOrUton Vtft I 

CHAPTER XIV. 
or THE NERVOUS SYSTEM. 

DMriaw ^Ot SmmB ^fatam.~Cinbn>-^iimii amd Sgmpaikatc.—fTbfota onf Vaicmlir. 

&neNn mml fS^^HmM ^ Nerve fihru.—OMr^mtat ami Omtrifmgal—naie of QMd^niUiiij/. 

At ml am l aa l Ejram ia ati e m ^ the Strmt^tme oiw/ Fwiriiims ofNore Vemeles. — Thry diffttte Injht- 
«UH, or* Magawn» ^ font. — Kievtoa of Time imtndactdtttf RegiMtrritig (imt^, — Q^Ja- 
Hm WMMu ry to Nwe Actirity. — Xece*nty of liepair and liest. — Ekrlrkal EiaaMoAom of 
lAc FkmOieiu y P «i efa r. — Anatomical and Elfrlriral Staminatioiu offrte, 

AKtomitlic Xerve An. — CtUattd Strva Arc — Mmkifde Ara. — CommiMnre».~~Btyi*ttnitg Aorr 
Arc*. — Sauorimn. — J^/trnxtiai Are. 

Sm^^Mkma darmrf/rOM otrwbral Strmlmt rttptOimy IM* Soul — Ha vidipmilait KxitOemet and 
Im m ortaBty. 

Idraa v/ Time and Span. — Ofr^ntfw, ttdgtctivt^ and imprrtoKni OprratianM. — Vertiffta ^ Im- 
prauimu end ifutir Inlfrprttatvm. — FinUt Sattre ofKnevlaiyt. — JftMlal Emottona S58 



CILUTER XV. 

THE S r I N A L AXIS. 
Primitirt Dertlopmatt of Nernmt Sytem. — It* final Co'dtlion in iUffatnt Vtrttbrata. 
TKt Spitwl CWd: ii» SfrmttMrt, — Itn yfemhraacx. — Jta Thirtf-OM Piiira o/" AVrrr*. — Prtpv- 

liea o/tktir liaou. — Ftactioiu of iSe Oird. — Htitg Dixovtry. — TranitmitMtn <^ Jjimffittidaial 

and TrantrVM fmjlitfnctM. — Rf/lex Attion of tke Cord. — A'afiirv ofSfjiex Action. — Motor and 

Stnm/ r y Trartu of the CanL~~:immvKiry of its Fmtctitnu. 
Tin MednSa Oblongata : ita SlrwJurt attd Funrtions. 
71c Amu Vanta : ita Stnutnrc and Fum-tiaaM. 
Dr. Qtrpmter'a Viaea of tkt Analogy bctwtien tht Spinai Cord y T «rt«Ara/e» and the Ventral 

Cbrd tff Artiaiiates 39E 



CHAPTER XVL 

OP THE BRAIX. 

The linriM : ita Ptnrtvn . — lit Afotor and Sentory Pijrta^ Htmisphma, and Ommiaamta.— 
Tht Sfnxorimn. — Variationa <{f the Jlemiipherta in Sisa and Wtiyhl. — Jnttrymmtat Xatvre 
^ CerAmm, — 7%: Ctrd/^Un: ita .Sfmettira and Ftmctionx, — Cb-on£na<es nmaaUar Motiona, 
— CfannfufMB arith Amathmtfaa. — PhrmoloffS.-~-ComStion» of Action of Drms. 

^mmetricai DonUtnaa* oftha Brain. — Function of each Hat/\ ami of hath conjmntly. — Independ. 
atee and Jnanbordinatiim t^eack JJcni/^rre.- — ZknA/e Thvwjht. — Aiieraaie Thoogfit. — Sfnti~ 
wtatt ^ Pn-eziatanee. — Lota of JWotption <^' 7<im , 313 



?! 



CHAPTER Xni. 
OP THE CRANIAL NERVES AND TUB GREAT SYMPATHmc. 

EmmanitioH of tht Craniat Xerr^s. — Thf Thint Pitir, or Ocuh-motor. — Tht Fourth Pmr^ orPom 
tAftifi. — The Fifth I'air^or Tritjrmim. — The Sixth Pnir,or Abdncenttt. — If/mitraliona oftha 
Third, Foorth, Fifth, and Sixth I^iira. — Tia Seventh i\iir, or Faeiat. — IflHslration of the 
FtinaL-~'rheXinihrair,or Chaxf^ph'trymiraf.—Ittnalrationyiha GtataofAaryngmL—'Tha 
Tenth Pnir, or Pnatmogaatnc^— ilhutnttion <f tht Pn m a wpti atric—IUnatratkat t^ tht. I^aryn- 
geals.— The Ekverth /\n>, or Spwal Acvamsry.— TKa Tm^h l\dr^ or l/ypoffioaaaL—II- 
iutratian of the HyjnKjtosaal, 

Tha Phrtnic Nerve. 

Of the Great Sympathetic Syatem.—PoaUio»^ Stnictura, and OHffin iftKa Syn^Mithetir.—Ita R^ 
iitioH teith the Pnaano-jaatric^Ita Oimectien with the Sjnnat Syatem.'-Ju J^Lama.—lU 



CONTENTS. 



XI u 



' Cmgila.—Tiei/ are iZeserroW of Force.— Sitmmary of the Fmetimt of the SymjfMthetic.— 

I JSRiiCrartM oftkt SympatJMie.— The AlMiomwai PUjntMut.— T/te Solar y&nw.— 7%e i/eam- 

tarie /^(mwu..... Page 333 

CHAPTEn x^1^. 

OF TUB VdlCB, 
Origin of the Vifiir^ — Co«9*arat!ve PhtfMio/wjy of Noue, Song, Voiot. — Diutinctitm Utwrai Sonff 

*tmi Spfrrh. — TV I^ryiu, ttatl itt Artion in Siiiffi«y. — Mkiitr'm KrjitinuttioH ofOtt Aditm <^ 

Mtf Vanxl Orffavt. — Sftenkiiuj AnxmalA and M(iciiinea. 
A'dfurc ^ WortU wtd tkar conttitvaii Sonnda. — I'ourc/t and Cmtomait*, — Whiajferiig.—'t/te 

of the Vw:;^ ^ AvimaU, 
(^ Ujaymag**: thtir Duratiott, (%iracter, Ilialury. — Rfffistry t<f Soundx hy Wrifitig and Prixf- 

inff. — itiuieai Signa. — Afytltahelie Writing gjil 

dUrTER XIX. 

OF IIEARINO. 
71W SaiM* -■ Gaurat JUmarJcs v/mm, — /Vm Orifana of Setu<. — Xttxssilt/ of Ajtjxiraiiujor M« 

AppnaaticM tff Tint, Spacer l*rrsavrf^ Ttviprralmr, and Chtmical QuaJiiies, 
Of JJeitriny. — GateratStntetitTttftht Orrfon <if IlMruiy. — I'/it/aicnf PtaiHaritiai of Sototd*, In- 

tmnry, Ttmt of Vibrution, ami i^aalitif. — The Tyntjnimimy Codika^ and SomdraUcMr Camtit 

are Jar the Afprtnalton of ihtJie jiecuSaritir*. 
Strmetmn and t'vnrJvmt of tht Tj^mynvum, or JHeoMurtmail i^f Intamty. 
Stncturt of the Cofhlat-, its •Sfirat I^ituitia and Sra&r. — MuuureM the Ttme nf Wtratiom.'^Ac- 

tOtpSthmatt of /nterfertnte m rAe Sailat. — Otmparatiet Anatamg of the Cochlea. 
Stnchirt of the Simieireuiar Qmalt. — Thtjf txtttnate the Quaht^ of Somds. 
CUywiml/w Anjtomy tjftheA vdJlory Afeckvusm.— Itt IVogrtn in UevdopiotHL — Imjterfectioa 

^dk iJoctrine o/ Means and Ends , 359 



CHAPTEU XX. 

OF VISION. 

AmaL^ bHtetm Sonad and TJffkL-^ Comparative Anatomy <^ M^non. — Perception af Wan^k. 
— Str>tci*rt ^ Oeetii. — 6«e of Laura. — P^gtiwI I^ncij4e of the Organ t^' Vision. 

tkieription ofiktlbtman E^t. — Opticat Atiion ofilM Part*. — Sjtherieaiand Chromatic AbtrtO' 
lion^—Rocfiving Srreen of the Eye i» the bitde Fiymait. — Lotig and short ^ight^ and their 
Cbrrtetion. — UmiU of Tutoit art induded in tmt Octave. — limit in estimating the BnghtaeAM 

flight. 

jVgi w JfedkDiitm <^ the Eye: it* Strmeturt and Ftmctian*. — Maimer of Percejitian hy the 
Btlina. — The bhek Pigment abtorU ihe Ilityn. — Single and double lleion-^lMtnuiim of Jm* 
pmmiom*. — Oeidar Spectra. — Erttt Vimon.—Jdea of the SoHdily of Sodia. — Jfypothait of 
the Actiom if the Bedna. 

AeeewmMj Apparatme of the Eye. — T^e Ey^brovt. — Eyetidi. — Lofhrymat Apparatta, — MwcUa 
ofitmBatt 370 

CHAPTER XXL 

OF CEREBRjU. SIOllT OR INVERSE VISION, 
n vrSnary ITaoh ami cerebral Sight, — Inverte Vision depaide on the Vesttgee 
t triating in the Brain. 

CbnfttMNi of our percetring these ImprtMsions is (hat they mast be ejuat in Intensity to prtsfht 
SmetUieae.— 7W Methods ofaeoon^bhtHg this EiptuUxation : 1st, by re-^n/brcing the ohl Im~ 
pnseims ; id. f>y diminishing the preamt Sensations. 
AvpoKV of obi Imjtrtssiaas in Str^ Feoer, Death. — Artjfifiul Emergence (ffamek Vestiges fry 

Prolottde if Xitrogen, Opium, etc 
GnUnl Sight meed teteotogicaily to imdicaU the JmmortaSty oftheSouL „ 401 



XIT CONTENTS. 

CHAPTER yyiT 

OF TOUCH, AND THB DETZRMINATION OF PRESSURES AND TEMPERATURES. 

Fimctiong of the tactile Meehamsm : its Stneture. — Higiotu of different SennHvenesM, — Compar~ 

ative Phytiology of TovtA. — EMtimatt ofphyncal QuaBtie*. 
Perteptioii of Temperatmn. — Svbjeetioe SenaatioHt of Temperatart ^age 417 

CHAPTER XXXn. 

OF SMELLING, AND THE MEANS OF DISTINGUISHING GASEOUS AND VAPOROUS SUB- 
STANCES. 

Structtire of the Organ of SnuU. — It» proper Inatrument the Fv*t Pair of Nervea. — limited It&- 
ffion ofSmeU. — Oonditiam* of its perfect AcUor. — IAiratio>i of Odors. — l^eir LocaSxatiam. — 
Sabjectire Odors 423 

CHAPTER XXIV. 
OF TASTE. 
ConStionsfor Taste. — Structure ami FuKOitms of the To^ue. — Tactile and Gustative Seffions 
of the Tow;ue.—QMHpkaientarif T(utes.—Subfective Tastes 427 

CHAPTER XXV. 
OF ANIMAL MOTION. 

I aiiary and Muscular Motion. — Description of CSUa and the Manno' of Action. 

Muscular fibre : it* Fomu, Non-striated and Striated. — Muscle Juice. — Manner of Oontraetiom 
<f a Muscle : its «^l>f of Blood-vessels and Nerves. — Its Chemical Change during Activity. — 
Its Rise of Temperature. — Effect of Electrical Currents. — Duration of Contractility, 

Doctrine thai Mutek Contraction is the result of Muscle Disintegration. — Manner in which ordi- 
nary CohesioH is brought into play. — Manner ^ Sesttmitum. — JSanoval of the Heat and Oxi- 
diud Bodies. 

Bigor Mortis. — Oofoiectionqf Muscle for Locomotion. — OfStanSng. — Walking. — Ranmng. 431 



BOOK 11. 

DYNAMICAL PHYSIOLOGY. 
COURSE OF LIFE. 

CHAPTER I. 
OF THE PRINCIPLE OP ORGANIZATION, OR PLASTIC POWER. 
lUmarks on the Subdivision of Physiology. 
Career of an Organic Form. — Three Modes of Decdopment. 
Inquiry respecting the tpedal Principle ofOrganixation.—Itluatrationfrom the GrovthqfaPlant 

in Darkness and Light. — Inference retpecting Plastic Posoen its Nature and Prcperties. — 

Of the ordinary Growth of a Plant, and the Sources from which its Materials are derived. 
Behiion of all Organisms to each other. 
Correction of the Doctrine if a Plastic Power, from Considerations regarding the ImBviduaBty 

of a Plant. — Plants are Operations, not Individuals.^I^ytical ISu^ratton of this View. 
Qmdueion re^tecting the Nature of the Plastic Power : thatitts aotntinued Manifestaiionifan 

antecedent physical Inytression *W 




CONTENTS. XV 



CHAITEH IL 
OF TUB INFLUENCE OF POYSICAL AGENTS ON TOE onOAKIC SERIES. 
Of the Gf*>fTriiplitf o/ I*tanin : iktir horwutit/ omt rrrtl'-al Lofalisalion. — Injtumire of Jleal On or- 
jytUNc /A'jtfn'AWKw; uothiral and iMn-Maiejuil Cowtiliowi, — EffvSu of Variatuti^K in l/u Den$~ 
U9 t^ l^ Air, AlouturCf SoU SmBj^U, LemjtA t^ Day. — Utjbiiie iluMity of iltat rfpartd 

bjf JitJRtM. 

StnJar PttiyrbationM in the Spteiea of Pltnt*. — Lim$ Period* qf Time rvynrrdL — Seahr ^tth^ 

logitai OuntgtM, 
Imm 'a t PnUan of iMe JuvtMiiyatitm of tke I'arth's IHtioryfrow htr/oisil Flora. — Ttto ffrtat 

ItmMtritsI Kftocha: Chaitge in the CoHatilution 0/ Uie Air, and Lvai/Ualion vf Ormtxixmw 

tkro»fih Z^tiiK of tht £aTlh'4 Interior lUat. 
D^emtm UliretH tibr*^ ivui tjnuivul imprtusiona. — Iiwariai/k Cmes Mrry prtxittrt nhmpt 

CHm». 

ExUmmm tftbe fAovt Prindpka to the Catt 1^ Animah.—CaK ifftlte Iitca /w/hw*. 

6 'a K Wl / Arymmeni mppt/rttd by lie JCxttttelioM cf Form». — DenAymait is imdrr Mr In/luoKt o/* 
Lgaf. — HmUmenUtry Organe and £r«jw* (^ Vert/opmnt. — The Idui of Ihvthgitnmt by 
Lmk eomtu\t»i witk nataral FaetM. l*ago -ITS 



OP TOE ORGANIC CELL: 



CHATTER UL 

ITS DEVELOPMENT. REPRODrCTfON, AM) DIFFERENTIATION 
OP STBlTTimt: AND PlFSCTinN. 

SimpU aaJ Swfhntnl CWZt.— 77U Simjtte CeU: ila Pktrit and Functioim.— Tfie yurlraUd Celt.- 
ks Ptrtii and Fanelions, — Actiriiy of the yvdetu. — Other FormM of CtiU. — CV/i« aritt by 
Stf^-ofiyiita i ioH tmd UeprodiKtiot. — Rrprwlmiio* hy SiAdivUien tad Undogmonaly. 

17k JUimal CVtf.— /onw </ C3r//iiAir Tt^tve.—Formi of Vavyitbxr Ti$me.~ Spiral Hwd^, 
O^tnmtiKtkm of OS: — AapMnttom of new FtmctioML — Difftrfuliatim oflhf Animat Ctti— 
Dfpmyft M i*kynad CauttA. — imfiuenct of Ueat and Air. — Fpock of Diffrraitiation .... 4S2 
B CUAITER IV. 

OF IlEPRODIJCTION AND DEVELOPMENT. 
Mitfw Q^ Oryaaic JSetmifM .- thry totite from a timiltr CcH and deretop to differmt Pointa.^ 
Thmr /Meitiom by CtoMtifixition ii jictitioHB. — Drrriapmmt and IMfftrrMiatioH. — IJomoijatfms 
«m/ ffeieraymttie.—' They dtpend on phytii-al OtnditioM. — Th* njirvdiKtivB Sluie dote* IM^ 
ttkymmt. 
DtvAfmmd iefrvm (Ac General to the SptdaL — Law of Ton Dor. — Inrariabfe SeqanM bt 

»0r SsrmotMnmox : Iw. Dy Gmrratiim. — Osmjugatioa and Fiiamcnt$,'—The Sperm-etB: ito 
Pmimniom. — ^prrmatoma. — TV (.'mw-rr/f.- iu J'rvduclion. 
Ontm in tAi Osary.—/te Stnteliat.-~Corjmii Ij^enm. 

Orwm lA the (hidMrt. — MH&rrry Miua. — (iermnal ifenttiraite. — The CJlorioB. 
Otmm im the Ptrrma. — Mttijirana lJecid*a. — iVocoifO. — iMrrtopment of the Smhrj/o. — Typa 

tfSmiriHon. — (y ConrefUiov. — Qf filiation. — Qf Parturition. — hjtoevot tfboth PurtnlM. 
fit By Grmmtffion, — DuddMff of PUinte and Animalt. — Of Grafiiny, — Limit of tronimifiwi.^ 

Xnfi mn rr nf Trmtprmtmrt cm Gfmutalio-i, 
dAanatiotu tf Generation* — Itt Erptanation 005 

Vjit/te^— IFf^ tad Site <fthe Tmfml.— Wfvjkt and Sis* at mAetquoit Periodg.—Detekp- 
- -t^tUlnteilect.—MahaitytfMaM.~TaukKcy to Oimc—ilaxima <tf Phywical and Mm^ 



CHAITER V. 
THE CBowrn or man. 



^ 9alS»a^ 



XVI CONTESTS. 

Afenialand IVtyncal Decline. — itorlality at SffWaU PcriodM qf Li/k.^Coiiyiaratiee , 

h'vnctiofiji, and Moriatisy of tht ttro SextM, 
Afijjicitii £podn o/L^e.'-Oraihiai Chanyt m t/x ilatal QmaStut^—InJipBuIiml Jgrffw^y ^ 

t/>eSemL ri«»tt8 

CHAPTER VI, 

or SLEEr AND DEATH. 

Cuufi o/the Nftf*tUif/hr Sbrp. — lu DvmtitM aad Maimer ofAjtproadi. — Mmimer t^Au 

Mjr. — Gout (jA yi^-»leip.—/ncrto»ed WarauA rofMrnl — Comwte t im ^ Sbip <md t 

0/ DrMuia: their Origin atni Pkmomata. — SomttttmhmBawi, — Stgktmta^ 

Qf'Detilh.—Old Age.—Inttrnai Oiuns of£)KH>m.~DtatK I3 Acti^nt mdlyOld Ayt.—7h 

Uij^toenUk Kice.— / wa/ /N«oif»6i&(y BAl 

CnAPTER YU. 

ON TIIC tKFLUENCZ OP mTSICAL AOENTS ON TUE ASPECT AND FOKM OP HAM , 
OS BIS INTEL LECTU AX. QUALITIES. 

DifftTmcat ra Form, llahH*, md Color t/Mtm^—Ideai 7j(p« «f Mim^^ltt Atomt owl J 

— Cmmt* ^fAiTM Variation*. 
J>KUim ^' th» l/mtf ^ 0» //tnun Ban. — Doctriat of ita Ortglmfwm ma^ Omtrtt. 
£ifimiKM ofJIeat on Co»g>iaicm.—GmM ^ OSmoM ^'aridtiBW.— /h/Immi of JInti ilUttnUed 

fry tU coKf Q^ tka Imio-Em r o p tau, lir ifottgoU^ iAs Ataeriam ladioM, and ti>» AjHtxpu, — 

I}i*triinaitM <if OoKqJexion im titu TrofHOit Jidieu. 
I'ariatiniu in the Sletetan, — Four J/mirx a/" fzaatiniag the StvU. — Cjimet^iaii o/'th» fJkapt ^ 

the iihiii and Mommt ^ Uft. — Fhytieat Cutset of Varintion o/*iU SkmS, 
Lt/luoKt ff the Artion ofikclAver en Com/tkxioH. — It^Jiuetot (jf the Anion qfthe Jjkrfr cw liW 

Form of the ShUL — fia»t Form nf SkmU ari*i»y frvm Ijmb om wtU as High TvnjKraJtirtM. — 

DiMoppmranet of tkt Etd-haireJ and Bhir-ryed Men im Furope. 
Tie iMcUectmil iimiUia* of Nations.— -SyntAeiicat ifutdoftke Ariaiu.^Ama!ytical Mind of ttm 

Smrcpean. — Tftdr mpectice OmtrHmtionM to liwnan Ciritiattiofi. — Sftreod rf iVrr^rmmfrfrni 

MM M .^frica. — Sprtad if Ciristiamty in Amtrixi. — Mtumtr tfOte /Voyre«* ^'aJi iVoA'aat 

ill CSri/uotwn fitt 

dUlTim VUL 
SOCIAL MECHANICS. 

Cbmparatitt Soaolo^.^-OiMnecHon of Struchin and Ilahttr^Oonmciion t^Uittory and Jln$ 
iologjf. — In»ect Sodetg. — iJtaoarta'i Doctrine that Itue<ii art ,i Mffrrnnffi jY>oiiiif| ^« 
MtrMnixm tf liftjiMtryfbr iHtiwt^ Ruuok^ and C^Hlisation. 

TVohuY nf M»tn, — InJhtmtM of nrrawndiny CireumstanceA on him, — D^Jinitmeu ofhtM GtrttTt 

GiUtULlt, Facti of £uKoreA!( UibTOBT. — Introdtu^ion <fFyg}ttian Cirdisatiom into Furvpt.-' 
Tie Hegistry ^FacU bj Writing.— Egyptian Fhiloaophy in the Greek St^hooU.— Tfw /Vr«t«n 
Et»inrt: it» Ii^nBKA, — Analytical Quality (f (Ae Exn^mn Mind. — /ft/Wwa if the GrtJt 
ixhoolx on modtm IHnioMfhy. 

Origin of European Otmmave. — Ditroeery if tht Sindtt of Gibrabar.'—MaeaimaM Qwy a ^ p, 
— Iteeonntnction ^ Monarchy in Ftjypt. 

1%» Moma Empire: iu enntra&siny and driBtIng Pou>er.—FaO of Smvptam J\iganinm.~-^ 
flamnt^the Chrism Chun^,— The Sabhnih Day.— The ftrformattai. 

Jj^finenca of Mohammedastitm on Eunt/tt. — Tht Arab jihyrical Srienai. — Thf OiuadlH. — ZXn- 
covtry ofAtneriia by the Spaniard*. — Fall of tht Spantnh fencer, 

Tjitrr Mental Otaapet 11 Fumpe. — Diai^ipairanen of Credulity. — Phyriologieal Change €f En- 
rujifnnt. — FffrrI of Mohammedanism in changing the Centre of InteJlect ofEurapt. — Anafyl^ 
ieai lendcROf if the Eun^xan Mind. — Adoantagte rteutliny thervfrom , „. MS 




LIST OF ILLUSTRATIONS. 



, The lower Jaw..,..., ; Wilson il 

Scriioii orSlom&cli .Auilior 43 

, pi}:e«titt> Tmcl Harrison « «, 48 

Mticoiw Mumhmncof Stuiaacb Wibon £0 

Stmnach Follicles and Tubes Todil and J$u\rinan CO 

Section of Stomach Tubes " " H 

The HvilfK 61 

IN8««iro Trace uf Buctic .Wine Edwards 58 

Mncons Atvrobrnna of Bcotle* Stomach Photograph bv Author £8 

Digestive Tratt of Fowl " " 68 

Slomnch of Africao Oelricll Carier , , 69 

■* ofDonnoasc " fiO 

" of Cope nyriw " 69 

'* of Porcupine " 69 

" of Porpoise " 69 

" ofKaog«roo " 69 

" of a Rominant " B9 

Posterior View of human Stomach Rebtius CI 

Poterior View of DaodcQam Botirgcrv 68 

DiAgrnrn of Brunocr's Rlaudu Author 60 

I>ia(f;run of Folliclu of LieberkiUm " 69 

PenreriAi) Glandi .'..Thomsoa 70 

Section of IlcoiD Wall KoUiker 8S 

Villi of Monkey Camera Lucida hy Author &5 

Villi of Daodcoum Jinthor 86 

Villi of Jejiinam " » 85 

Section of VilU " «, 86 

■VtniofSqoirroI " «. 88 

». Prindjilc of Vcniuri « " 90 

W. Thoracis: Duct -WUbod 90 

I). Cbjle Corpascles with Illood-rellt „ Photof^raph hj Author 98 

n. " '* " Water Author 94 

Uv •• " " Acetic Acid " „ 94 

SI, Irjinpliaxict of Iat^u Intestine „ Boargciy , 07 

2i, Ty'tAgnm uf Lftupb Gland ^ Goodsir 07 

34, Rrolnlion of i>vmph Cells •* 97 

S7. Cafillar^ I>i'prvMion uf a Li(]uid Author 104 

Ift. Cafrtllary Klevation of a Liijaid " 104 

39. Paaaai^o of Water through a Creviee " lOS 

*0. EDdoaToomctcr " „ 106 

41. BolotrtltiK Power of a Membraue " 108 

43. Iloniwi B1oo(1.4-elU Photo^^raph bj Author 116 

4& Elliptic Blood^elU „... '* " 116 

4*. AaUu of Water on elliptic Cella " " UB 

«i. Action of Acetic Add •» " IIT 

Be|«ile Dlood-cellB « « IIT 

Hnnu Btood-crjitolf , ...Lchmaao 119 

A 



2 LIST OF ILLUSTRATIONS. 

VM. Mat 

40. Blood-crystals of Gainea-pig Lehmann 119 

49. Blood-ciTBtalfl of Squirrel " 120 

50. Stellated Blood-ceiU Photograph by Author 127 

51. Capillary Motion Anthor 131 

62. Motion in CelU " 132 

53. Circulation in Tradescantia " 183 

54. Diagram of Fish Circulation Milne Edwards 135 

65. Radimentary Heart Thomson 135 

56. Diagram of single Heart Roget 136 

57. Heart of Dagong Home 136 

56. Hnman Heart on right Side Wilson 136 

69. Htunan Heart on left Side " 137 

GO. Moscnlar Fibres of Heart Author 137 

61. Vessels of Mocous Membrane of Stomach " 143 

62. Vessels of Villi of Duodenum " 143 

63. Capillary Circulation of Fred's Foot Wagner 143 

64. White Corposclea in th& still Layer '* 143 

65. Valves of Veins open Rogct 143 

66. Valves of Veins shut " 143 

67. Diffhtion of Gases Author 153 

68. Diffusion through Earthenware " 153 

69. Diffusion through India-rubber " 15S 

70. Passage through Films '* 153 

71. Force of Filtration " 155 

72. Air Vesicles of Insect Fabricius 157 

78. Spiracle of Insect Photograph by Author. 157 

74. Air Sac of Fish Blasius. 167 

76. Lung of Reptile Flourens 158 

76. Lungs of Frag " 169 

77. Human Air-tubes y Wagner 160 

78. Heart and Lungs " 160 

79. Capillaries on Lungs Rathke 160 

80. Mechanism of Respiration Author 161 

81. Experiments on Respiration Regnault and Rcisct 170 

82. Hepatic Coecnm of Cray-fish Lcidy 198 

83. Bile-ducts entering the Duodenum Paxton 199 

84. Hepatic Veins in the Lobules of the Liver. Kieman 199 

86. Origin of Hepatic Veins " 200 

86. Origin of Bile^ncts " 200 

87. Hepatic Cells " 201 

88. Section of Kidney Wilson 215 

89. Diagram of Malpighian Corpuscle Kotliker 216 

90. Glomerulus of horse " 216 

91. Cilia on Uriuiferous Tube Bowman 216 

92. Diagram of Malpighian Circulation '* 217 

93. Malpighian Toft Isaacs 217 

94. Ruptured Malpighian Coil of Deer " 217 

95. Nucleated Cells on Coil " 217 

96. Development of Mammary Gland EoUiker 225 

97. Section of human Mamma 225 

98. Colostral Corpuscles Photograph by Author 2!!5 

99. Epidermis of Dog " " 235 

100. Section of Skin Kolliker 236 

101. Under Surface of Cuticle Todd and Bowman 286 

102. PapilUe of Palm '* " 285 

103. Skin of Palm « " 236 



LIST OP ILLUSTKATIONS. 



. Section of Hair TixlJ nm\ Di^vrmnn 2JS15 

. TrnnsTOTM Section o( Hair ....IMiotograph ty Autlor I'll? 

. SailoriparDus Glanil Wagner ay7 

, Fat-cell « Schwann LM6 

. AdifioAo and orcolor Ti»tu« ».>o Berrea 316 

. Trantvcna Scctiun uf Bonc Pbotognipb by Aotbor..... SM 

. Larnnic aad CunalicuU Author 354 

. Owifnoj; Canila;:c Kollikcr 255 

. (Httfyin^ Cartiliigc rhoto^^ftph by Author 2it> 

. OtsifnnK Femur Kolliker SiJO 

. AxisCrliadcr. Author 2fil 

. SuUirision of Nenre Fibres Kollikcr 2G'i 

. Xerre.«eU3 " M3 

. Bipolftr Nerve-cells ,. ** £M 

. Mulripokr NervD-cel) „ „... Author SOI 

. Utrre CcIU and Tubes Wagner 8C4 

, Nenro Cell* und Tiilw-t Purkinjc SG4 

. Donal Gan(;lioD uf Moii»o.,..„,. .Valeatin SOT 

, Simple Rniiimnlic Arc Aothor 277 

, Siiuplo cellutcd Arc ,.„ '• „ 278 

Multiplu Xerre Area '• t7fi 

. CtimmisMiirvd Arci •' 270 

. Nor^'i^os ^vBtctu of Larva of Sphinx Ligiistri..,. Newport 279 

, Kcrroax SvMeni of I'upa of Sphinx LifpuTri " 279 

, Nervoni Srttein of Iiimj'O of Sphinx Ligiwiri.... " 270 

, NVfvon* Svstem ofAsicrias Ticdenuinn... 270 

Nenroiu Srstctn of Patella Cnriur 279 

, Xtrvoiui System of Octn]>ufi " 270 

Kcr>oas System of Aplysia " 280 

. Regutcring Kervc Arc Aatbor. 281 

Sopfmssion of Centrifngal Branch ■* SSI 

InHuonlial Arc *' , 883 

Primitive Trace * BiAcbufT 293 

Oriftin of Uniin on .Spina! Cord '* 293 

Spinal Cord Phtrtop'aph from LevsiIIi< S9A 

Section of Spinal Cord " *• " 29ff 

Spinal Dura Mater «< " " 293 

Origin of anterior Itoou of Xcnes u « w 297 

Orifcin of poftterior Itoots " " •* 297 

Ori^n of both Rixiu „ " " •• 297 

Portion of Cord of Spirostrc[>l08 Xewport 801 

Front of Mudnlla Oblon^nta Pltoto;;rapli from LevcilK* SOri 

BACk of Medulla nhlonirnu •• " " 305 

Intcriitr of Mcdnlln and Pons '• " " 805 

Posterior View of Med alia Oblonpaia Todd and Bowman SOfl 

NcnwH Synicm of Lar%-a of Sphinx Ligiuiri ....NcwikwI 308 

(^n;lion of PoIyde^muB MacnUtni " ,., 309 

Oan^liun of (Vniiiicde •• , 313 

TbuTucic Portion of Cord of Sphinx L<t;|^tTi.... •• «.. SIS 

KMpiniorr and locomotive Ganglia " 318 

lUtcmal JRleril Fnce of Brain Photo;;niipli from LcveiUt.* 813 

Superior Afpcctof Brain " " " 818 

InttniH] lateral Face of Brain ** " " BIT 

BoMt of Brain Photograph hjr Author 817 

Diaitnun uf Brain Mayo ».«.... 818 

Tbo Motor Troa Bell »l» 



4 LIST OP ILLUSTIIA.TIOXS. 

«•■ rMt 

160. The Sensorr Tract Bell 320 

161. Nerves of the Orbit Photo;nT>ph from Leveille Sa* 

162. Nenes in the Orbital Cavity " " •* 33.> 

163. iJiagram of the Fifth N'cn-o " " '• 335 

161. Ganf*Uoii of Gosscr " " " 33.> 

16o. The Fifth Nerve " " " 336 

166. The inferior Maxillary '■ " " 33G 

167. The Facial Nerve " " « 337 

168. The GloftBO-pharyngcal Nene " " '■ 339 

169. Diagram of Anastomoses ■* " " 339 

170. The left PncumuKastric " " " 341 

171. Pulmonary Ganglia " •• " 342 

172. The inferior LanngcalH " *' " 342 

173. The II\-pog]o5sal Nene " " " S43 

174. The Phrenic Nene " " *' 344 

I7.'>. Relation of the Sinnpathctic and Sjmial ToUJ and Domnan 345 

17C. The Great Sympathetic Pholograjih from Leveille 848 

177. AWominol Plexuses , '■ " " 349 

178. The Solar Plexus *' " " 350 

179. The Mesenteric Plexuses " " " a-,0 

180. Spiracle of Insect Photograph bjr Author 352 

181. Profile of Larjnx Lcrcilli 354 

183. Posterior View of Larv-nx " 3.'>4 

183. External, middle, and internal Ear " 362 

184. Tympanic Cavity '• 362 

185. Facial in the Aqueduct of Follopius " 302 

180. Interior of Cochlea " 309 

187. Section of Cochlea '* 369 

188. Magnified Section of Cochlea " 370 

189. Cochlear Nene " 370 

100. Auditory Nene ; *' 370 

191. Ossicles and their Muscles " 370 

192. Tj-mpanic Face of Lab>Tinth " 374 

103. Cranial Face of Labyrinth *' 374 

194. Interior of Labyrinth •' 375 

195. Interior of Labj-rinth " 375 

196. Profile of Eye " 383 

197. Front View of Eye " 383 

198. Section of Eye " 383 

199. Veins of the Choroid " 385 

200. Arteries of the Choroid " 385 

201. Yellow Spot of Soemmcnug Soemmering 38<> 

202. Membrane of Jacob Jacob 390 

203. Simple Papilhc. ■. Todd and Bowman 420 

204. Com|K>und Papilla; Kollikcr 420 

205. Olfactorj- Ner\e Loveillft 424 

206. Olfactory Nene " 424 

207. The Tongue i Photograph from LcveilK- 42a 

208. Ciliated Cells Author 431 

200. Ciliated Animalcule Ehreuberg 432 

210. Hydra walking Tremblcy 432 

211. Striated muscular Fasciculi Photograph by Author 433 

212. Human Sarcolcmma Bowman 433 

218. Sarcolcmma of Fish " 433 

214. Ultimate muscular Fibre Photc^rniph by Author 433 

215. Uastnped muscular Fibre Author 435 



LIST OP ILLUSTRATION'S. 



B 



2lfl. Unstripcd Fibres in Acetic AciJ Author 4aj> 

217. Mttscle CelU Kolliker „ 485 

218. MuMTular FxM-icmli turn in IH-ws Bowman 43S 

210. TransviTse Section orimmun .Miucle " 43T 

2iO. Tnin»TCT»c Sociion of Miiiflcff Teal " 437 

221. Non-fittrilUtcd Iiiiwct FnHfiLuli ]MloUJ^^aph by Aatlior iSJ 

232. Noii-fibrillntcd Inwct FoMK-nJi .-» " » 487 

223. Coairnctinif MumJc of l)yti»cu» Bownirn 48d 

221. Nircotomma rnLied in Bullic Tudil and B^m-tooD 48$ 

22.*?. Faju'irulus roiitrnirlins .— " " i3& 

22B. l>t«intjtiti(>a of mutxriitar C«t>illaries Berrwi 489 

227. Mtufrilfir Ancric» ami Win)..... Kollikor 440 

228. Di-HritMition of miucultir Xcnce Bnnlacb 440 

229. VohiTiic of conlrnrlitig Musclo Autlior 4JS0 

33ft. ITuTmiUHfKTii'i Binnlts Ilatwili , 4M 

231. Conferva plomcrata Mohl 493 

J32. Simple Ceiliilar mfnue PIiotiWTtph by Author. 407 

253, MHrirnrmCelluliir Tissue ** " 497 

t3t. FihnKfflliiUr TiMnc ** " 4»7 

SpinU VcsseU of Camia " " 498 

Sjiml VcsrcU of Buiiaiio " " 498 

W(«i.)y Filire of Fine " " 498 

Yellow Fibrous Tissue Author 489 

\NTiiic Fibrooi Tiwuo " 499 

Areolar TfauiM " 41HI 

Devulupment of Frog ..Rusconi. 



237. 

r». 

310. 
311. 

:«. 

:i3. 

Zi4. 
245. 
SIS. 
347. 
24a. 
«49. 

2ao. 

Kl. 
552. 
2M- 

2;w. 

2M. 
2.17. 

2,W. 

2frf>. 

jni. 

2fi2. 

sra. 

2CI. 
2C5. 

2tUl. 
267. 




Fro;; filO 

Dcvclfpntutit )ir<''nit) Coui*h A 10 

DerDtof intent of In!««cU Straus Durckboim AlO 

Zyf^acxnii Qiiioinam Kiitxing fi15 

Tr!itii Arnold fliT 

I>e\-eln|>menc of Spcmmtazoc Wafni*ir A18 

Section of Orar>- Kotlikcr B21 

Section of Graafian Vesirle Von Bar D21 

Onint Bnrry fiSl 

Pinf^ram of Oraufiao V'csicto Kirkcs and Fapct £21 

Cxirymra Luten Pattcnoa and Muotgomorr G2tf 

Ovarian Otam S23 

OTHrian Ovnm o28 

(^{•mentation ofOrnin Bischoff fi24 

Kciimpntfliinn ofOrnm Kolliker and Bagg.. £34 

I'terinc Tube.* Weber „ 596 

Laycn of ttcnoinal Memhnne BtetcbolT 5S7 

Frimitlve Groore " 627 

Origin ofBrain '* 538 

I'rodiiction of Vessels , llTafnier KI9 

rrudtK-iton of Lympttatica Kolliker 539 

Rudtmenlnry Ucan Thomson 539 

Forlal fican Von Bdt 680 

lit lira budding Tremhley 684 

Newton Photograph from Prineipls SC8 

Atutrniian „...„ D'Uirillc. — Photograiihcd from rridurd SOS 

Aa«trttlian» D'Unillc.— " " " 564 

Bmlimin BranwUite.— " " " B73 

Oiioaa* " " " r.74 

KaiBtachaUiale " " " 57S 



G LIST OF ILLUSTRATION'S. 

*i«' rut 

272. Sac Indian Catlin. — Photograpbetl from Pricbard .IT". 

273. Cherokee Indian Catlin.— " " " 576 

274. California Indian Chora.— " " ** 676 

275. California Indians Choris.— " *' " 576 

276. Abyssinian D'Abbadie.— " " •' 677 

277. Native of Madajrascar " " " 677 

278. Native of Mozambi'jue •' " " 678 

279. iicgro of Guinea Aathor 670 

280. Philippine Negro Choris. — Photographed fromPrichard 579 

281. i^kcteton of Man, Chimpanzee, and Orang Photograph by Anther 681 

282. Skull of European Prichard 682 

283. Skull of Negro " 682 

28*. Skull of Chimpanzee " 582 

28r.. Skull of Orang " 582 

286. Caucasian SknU " 683 

287. Mongol Skull " 583 

288. Negro Sknll " 584 

289. Titicacan Skull •* 584 

290. Base of human Skull " 684 

291. Base of Orang Skull " 584 

292. Esquimaux Skull " 58."> 

293. Negro Skull Author flS7 

294. French Skull " .187 

295. Ccphnlic Ganglia Newport G07 

St9Q. Thoracic i'urtion of Ventral Cord " 6U7 



HUMAN PHYSIOLOGY, 



STATICAL AND DYNAMICAL. 



HUMAN PHYSIOLOGY. 



BOOK FinST. 



STATICAL PHYSIOLOGY. 

CONDmc»NS OF LITE. 



I 



CHAPTER I. 

nmStionii tifUp. — Xalvre oRdSovrtet t^ Sthttanrrx gujipUotlQ the DoJif. — AttatutHiMUititirs 
rtymmt — TitlU nf Pht/xiotiMiinU SttmdivdM.—Ainmnlt da not create^ tut trxmtj'ornt SfAnan- 
ttMn—PrefKrHei aud QwiHlitirA of Maittr* remrvd by ihr .^yxtfn. — I^mprrtits latd Qfiantififm 
l^tkoM it rritara. — Hmt t>f the fivdg arva/rvm Gufil/usthn,— G>o/i>ij At/nv^i^:* in an Ai*- 
imat. — Stcetnig of liffifiirs in the St/ntrtn, — P/ti/slail Aiyteti of Man. — 77rf Sou/. — T!ie Vital 
l*rimrifite. — ImportoHo: iff' } 'htfsi'-al Srirmx to S^ynotiyfjf. 

For tlic ranintenancc of the life of man thiYjo diomicnl conditions tnufit 
l»c complieJ with. He must be fumislicd with air, water, aiid combusti- 
ble matter. 

Under the same conditions, olao, all animals exist. Even in those 
whicJi flccrn to furnish us witli iustaiiccs of do|)arturc from this Tlirwiwidi. 
general rule, the exceptions arc ralhcr apparent tiian reah To '^**" of lift. 
biesthc, to drink, to eat, are tiic indispensable rcquiditoa of life. If there 
be amon^ injects some which seem never to take water, or among liahcs 
some which ne^'cr taste solid fuod, these peculiarities disappear as soon 
as we understand them properly. Where a high development has Ixxn 
attained, as in man, experience assures us that the same i^e^'itablc result 
awaits a ocs.iation of respiration for a few moments, nn abstinence from 
water fur a ie^ff hours, or from food for a few days. 

The supply of a part of thesu necessaries of life is adjusted to tlie ui^ 
gency of the want. The act of breathing is incapable of de- sonrw of imp. 
lay, but the air is accordingly every where present, and al- piy^f'"*!**"*!. 
vays fit for use. We can bear with thirst for a little time, and the earth 
hcTP and there furnishes her springs and other stores of water. But far 
otherwise is it in the obtaining of food. It la the lot of all animals io 
uouri^hment by labor, and even of men the larger proportion, botb 



10 EQUILIBKIUM OF UFE. 

in civilized and fiavoge countries, Bubmit to a hard destiny. To obtain 
their daily bread is the great object of life. 

What is the philosophical explanation of this necessity for a supply 
of air, of water, of food ? ^yhy is it that the system will bear so little 
delay ? 

The answer which Physiology gives to these questions is an answer 
Life dc 11.1s **^ ominous import, but the whole science is a commentary on 
on destnieiion its truth. The condition of life is death. No part of a liv- 
matenn . ^^^ mcchanism can act without wearing away, and for the 
continuance of its functions there is therefore an a^olute necessity for 
repair. 

It has been greatly to the detriment of physiology and the practice of 
medicine tliat this conception has not been thoroughly realized until late 
times. The aspect of identity which an animal presents is an illusion, 
hiding from us the true state of the case. It has been the fruitful source 
of errors which have retarded the progress of these sciences. What could 
their career possibly be when men had persuaded themselves that a liv- 
ing being possesses a capacity for resisting any cliange, and tliat organic 
structures never yield to external physical influences until after death ? 

But life, far from being a condition of immobility, is a condition of 
ceaseless change. An oi^nism, no matter of what grade it may be, is 
only a temporary form, which myriads of particles, passing through a de- 
terminate career, give rise to. It is like the flame of a lamp, which pre- 
sents for a long time the same aspect, being ceaselessly fed as it ceaselessly 
wastes away. But we never permit ourselves to be deceived by the sim- 
ulated unchangeableness which such a natural appearance offers. We 
recognize it as only a form arising from the course which the disappear- 
ing particles take. And so it is even with man. He is fed with more 
than a ton weight of material in a year, and in the same time wastes more 
than a ton away. 

There is, therefore, a general condition of equilibrium which every an- 
Conditinna of ™^ presents, depending upon its receipts and its wastes, a 
eqniliiiriumia proper knowledge of the conditions of which is at the fonnda- 
"*"* tion of Physiology. That we may approach this problem un- 

der its simplest form, iree it from all unnecessary complications, and make 
it of most interest to the special object of this book, the remarks now 
to be made will be confined to our own species, and, except when oth- 
erwise stated, to a condition of health, and to the adult period of life. 

To have a uniform standard of reference, we may assume one hundred 
and forty pounds as the weight of an adult healthy man. Now the con- 
stant consumption of food, water, and atmospheric air tends steadily to 
increase tliat weight, and even in a very short time a disturbance arising 
irom these sources would be perceptible, were there not some causes of 




I 



componsation. But even at'lcr a year, if a stale of Jiealrii is maintained, 
the weight may remain precisely what it was, and this may continue year 
lifter year in sucecssion. Tlio coiisumptiun of lar^ quantities of eolidi 
liqniil, and gaueous matter docs not therefore necesaariiy add to the 
weight. 

Tlicre nro two periods of life for which thi3 observation will not hold 
Tlicy arc infancy and old age, Diirmg the former tlie weight in- 
SC3 from day to day, and during tlic latter it slowly deeline*. 

If there be thus causes for the increase of weight of the living system, 
there arc also causes for its diminution. Setting aside the minor ones* 
these may he cliieHy cnnmcrated as loss l>v urine, by firccs, by transpired 
and expired matters. Ily transpired matlcrs, arc meant anch as escape 
under the form of Liquids and gases from the skin, and by expired mat- 
ters, vai>ors and gases escaping from the limgs. There is, therefore, a 
tendency to an increase and a tendeiicy to a diminution of llio weight, 
and, in the condition of equilibrium we are considering, these must bal- 
aneo one another. 

[f a man of iltc standard weight abstains from the taking of water and 
food, a good balance will pro^ e that in the 0001*86 of less than an hour he 
become liLrhtcr. If he still |>ersi9ts, it needs no instrument to detect 
.t ijt going on ; the eye j»erceives it, for emaciation ensues. 

1 low, then, is it possible for a li\-ing l)eing to continue at its standard, 
except the causes of Licreasc are precisely equal in effect to ihc causes 
of diniiimtion ? Overlooking minor ones, we may therefore assert Uiat 
the sum total of food, water, and atmospheric air taken m a given period 

time is precisely equal to the sum total of all the losses by urine, fic- 
transpired, and expired matters; for if the receipts were greater, the 
weight must incroase — if the losses were grcyiter, the weight must dimin- 
ish. Persistency in tliis respect proves equality, and the case is just as 
simple OS in the common afiiiirs of lite ; he who pays less than ho receives 
grows rich ; if his payments are more than his receipts, lio becomes jwor ; 
Imt his condition is unchanged if his payments and receipts are equal. 
Iitiaiicy, old age, and nuuihuod answer to these circumstances respect- 
ively. 

From tlic army and navy diet scales of France and England, which of 
course arc based u])on the recognized necessities of large Qamiityor 
Btunbers of men in active life, it is inferred tliat about 2i ""»""^i«i«<' 
poonds avoirdupois of drj* food per day arc required for each yror. 
individoal ; of this about three quarters arc vegetable and the rest animal. 
Al the close of an entire year the amount is upward of SOO {>ound3. 
Enumerating tinder the title of water all tlic various drinks — coffuc, tea, 
olcoliol, wine, &e. — its estimated quantity is .ibout 1500 pounds per an- 
nnm. That for oxygen may be token at 800 pounds. 



M 



12 ANNUAL REeSIPTS AND WASTE IN MAN. 

With these figuroe l^eforc as, we are able to see how the case stands. 
The food, water, and air which a man receives amotuit in the aggregate 
to more than 3000 pounds a year ; that is, to about a ton and a half, or to 
more than twenty tiroes liis weight. This enormous mass may well at- 
tract our attention to the expenditure of material which is required for 
supporting life. It reveals to us the fact that the old physiological doc- 
trine, that a living being is not influenced by external agents, is altogether 
a fallacy. A living being is the result and representative of change on a 
prodigious scale. 

The condition of wjuilibrium which has just been set forth, moreo\"er, 
QnantltTof leads to the conclusion that the aggregate weight of urine, 
iM^mm^'n m^ f*ces» transpired, and expired matter is the same for the 
year. Bamc period of time. In round numbers, we may take it at 

a ton and a half. 

It can not be questioned that the materials which are rendered back to 
the external world, after having subsen'cd the purpose of the animal and 
passed through its system, are compounds of those which were originally 
received as food, drink, and air, though they may have assumed in tlieir 
course other, and perhaps, in our estimation, viler forms. Recognizing 
as indisputable the physical fact that not an atom can be created any 
more than it can be destroyed, we should expect to discover in the sub- 
stances thus dismissed from the system every particle that had been 
taken in, 

"Wliat, then, is man ? Is he not a form, as is tlie flame of a lamp, the 
temporary result and representative of myriads of atoms that arc fast 
passing through states of change — a mechanism, the parts of which are 
unceasingly taken asunder and as unceasingly replaced ? The appear- 
ance of corporeal identity he presents year after year is only an illusion. 
He begins to die the moment he begins to breathe. One particle after 
another is removed away, interstitial death occurring even in the inmost 
recesses of the body. 

From these general considerations we infer that the essential condition 
Great extent of of life is wastc of the body ; and this not only of the body 
the ByBtem of ° ^^ *^** ^^ggi^gatc, but cven of cach of its particular parts, 
man. Whatever part it may be that is exercised is wearing away, 

and wherever there is activity there is death. And since parts that are 
dead are useless, or even injurious to the economy, the necessities simul- 
taneously arise for their removal and for repair. Much of the compli- 
cated mechanism of animal structures is for tlie accomplishment of this 
double duty. 

For an organic being to live, its parts must die. The amount of activ- 
ity it displays is measured by the amount of death, and in this regard 
every member of the animal series stands on the same leveL Here, at 



FTKED STANDARDS OP PHTSI0TJ30T. 



There has never Ixicn created such a timig as on 



Uifi very oiitspt of our science, we must (lipTtiisa the vulgar error lliat tho 
physical conditiona of cxUtenco vart' in different tribes* and that ntaii is 
not to be compared with lower fonus. We must steadily keep in view 
the interconnection of all, a doctrine whicli is the guidiug liglit of modem 
phyaiolog)', and which authoriiica us lo appcjd to the structure and func- 
tions of one animal for an explanation of the Stmctnro and functions of 
Tlie more steadily we keep before U3 this philosophicai con- 

'i^ition of the interconncctiori of all organic forms, the clearer will bo onr 
physiological views, 
isolated bring being. 

From tho uiaiuu^r in which these general con si deration a of tho mechan- 
ical and chcniicjil equilibrium of tho system of man Iiavc been Xcccawityind 
introduced, it will doubtless be seen that it ia the first buai- JL^'ipiSli 
ncsa of the physiologist io disentangle the variable results "liindarJ*. 
whicii that systcni presents, as (or as may be possible, and oifer tiicni un- 
der a staudani estimate ; Uiat at the basis of this science there should 
\fC a tabic setting forth with the utmost exactness all the quantities con- 
cerned in such a standard tjlM?. Thus, assuming the weight of iui adult 
man at 140 ponnds, as we have done, it should show the dinmal consump- 
ti'-'i ibuslihlo matter or food, of water, of air — the diurnal loss by 

cv... I, by socr<;tion, by rcjipirution. In contrast with this it should 

alao give llic nocturnal. It should also rc]ireitcnt the quantity of bile, 
(^ saliva^ of pancri^tic juice ; the weight c>f cjich one of the various salts 
and organic Imdles they contain, the diurnal and nocturnal production of 
beal,t^c. 

For the purpose of the practice of raodicinc, a standard of 140 pounds 
will perhaps be foujid most convenient, but in a scientific point of view, 
and especially for comjMirativc ph^'siology, a standard of lUOO parts is 
beat aasuined. I now present an attempt at tho comstruclion of eudi ta- 
bles, it Ifcing perhaps scarcely necessary to apologize fur their cxlreinc 
imjicrlection. Though offering the resuUs at present received as moat 
tniatnorthy^ a vcrj- auporiicial examination will show Iiow full they nro 
of errors oiid contradictions. iVrliapa it would not be too nmch to say 

, that it will rerjuirc the labor of many physicians, continued for centuries, 
to bring sucli tables to tho trulli. Yet the approach to j)recL''ion in these 
hypotlietical constants will in all times lie a measure of the exactness of 
|Jiyaiulogy, and it may Ix; added, also, of the practice of medicine. Tho 
lime U nt hand when such a tj*pical standard must be the starting-point 
for pathology, and no rational i^racticecan exist without iL The passage 
of physiology, trom a speculative to a positive science, is the signal for a 
rsvolatJon in the practice of medicine. 

Jloreovcr, physiology should furnish formulas for the compntalion of 
Tariations in these tabular numbers under variable conditions : u^, fur in- 



14 FIXED STANDAKDS OF PHTSIOLOGT. 

Stance, under low and high aerial tempera ttiroa, change of atmospheric 
pressures, absolute quiescence, or the near approach thereto, the eSect of 
a determined amount of locomotion, or other muscular exertion, &c. As 
the science becomes more perfect, it shoxdd likewise attempt to embrace 
pathological states ; as, for instance, the diurnal or periodic production <^ 
heat in fevers, the effect of the hy^enic system of the bedroom. 

Physiology having attained to this high condition, the practice of med- 
icine in its great department of diagnosis will consist, in reality, in the 
solution of inverse problems. Given the variations from the standard ex- 
isting in any case, to determine the cause of those ^'ariations. At this 
point diagnosis becomes a science, and ceases to be an art. 

As in painting and statuary, the artist has an ideal model in his mind, 
ni (ratio f ^ typical standard which no living being has perfectly reach- 
the following ed, thougli some of the most beautiful may have approached 
**** *• thereto, so in physiology the standard or typiod man pre- 

sents the combined and mean values of nil tlie human race. 

A less comprehensive view presents us with distinct national standards, 
instead of this universal one, for every country has its own peculiarities. 
Keaults of the highest interest arc to be perceived when these national 
standards are compared with one another. Even the same nation must 
offer, from age to rgc, modifications in its t}-pe expressive of the secular 
perturbations it is undergoing, as it advances or descends in a knowledge 
cf the arts of life and civilization. 

llorcover, there are typical standards of a still lower order, ha\"ing ref- 
erence to the conditions of sex and the period of life. Of these six may 
be designated — the infant, the adult, the aged, cf the male and female sex 
respectively. 

As illustrations of these remarks, and examples of the detcnnination of 
the fundamental element of such a general physiological table, the stand- 
ard weight of the body, we may take the following estimates. An ex- 
amination of 20,000 infants, at the Matemitd in Paris, gives for the weight 
of the new-bom Gilbs. ; the same mean value obtains for the city of Brus- 
sels. For about a week after birth this weight undergoes an actual dim- 
inution, owing to the tissue destruction which ensues through the estab- 
lishment of aerial respiration, and which for the time exceeds the gain 
from nutrition. For the same age the male infant is hea\'ier than the fe- 
male, but this difference gradually diminishes, and at twelve years their 
weight is sensibly the same. Three years later, at the period of puberty, 
tlie weight is one half of what it is finally to be, when full development 
is reached. The maximum weight eventually attained is a little more 
than t\\'enty times that at birth, this holding good for both sexes; but 
since the new-bom female weighs less than the standard, and the new- 
bom male more, the weight of the adult male is 136^^^ lbs., and of the 




I 



I 
I 



t female ISl-^y^u lbs. The mean weight of a man, inrcspccli 
period of liie, is 103.^1^^ lbs., and of a woman ^'^f^s ^^*' '^^^^ mean 
wei|rfat of a human being, without reference either to age or sex, h 

98,yyv lbs. 

For the preceding nnmbers we arc indebted lo the researches of M. 
Quetelet, who likewise has in an interesting manner extended the metli- 
ods of statistics to the illustration of the physical and moiid career of 
num, and impressed us with the fucts that in the discussion of the phe- 
nomena which masses present, individual jHsculiarity disappcfirs and gen- 
eral laws emerge. The actions which seem to be tlic result of free will 
in ibe individual, assume the piise of necessity in the community. Just 
03 wo are sure that man is bom, develops, and dies under the operation 
of laws that are absolutely invariable, so communities soom to bo under 
the influence of unchangeable laws. '^ In communities man commits the 
Bamo number of murders each year, and dtKS it with the wimc weapons. 
We might ennmcmto bcibrchand liow many individuals will imbrue their 
hands in the blood of their kind, how many mil forp?, how many poison, 
very nearly as wo enumerate beforehand how many births and deaths will 
take place."* 

PHYSIOLOGICAL STANDAIID TABLES. 



■a^l to M» IM. Mf 0lldDt«tk 


wvlf ht to IOM> pMU. 1 






i 




-■ 




i 




T, 


b 


Vrf ncwtahiA food . . . 1.097 


u 


1)17 v.-Ki-teblfi rood . . llliMt 


£ 


^ 


J*TY ■nlBwl food 4,<W1 

Mlvn VLSia 


















l^wn<«Ur JulM Ml) 




euimatlcjulc« S.145 


^ 


Wla itixt 


J 


IMk 14000 


i 


f Xrhnn rmm dtnga , . . .AflO 


^ 


C«rlMin fMitn Innjp. .. l-fiTI 


a 


Ul««rlB>l }iilr« MO 


3 


IntMltDftlJalm B.IM 


£ 


LiM*«f WBivrk/ liuii;« I.MO 


e 


Lotf or wnbtr by lungm lO/.-Ml 




•■ akin, tttl 


B 


■kta. l&VM 


n 




J 


F*c« K1 


Ifr 




•o , 




■' 




1 
1 

1 


Water 7u.0V 


1 

; 








lACtleacM (0T 


tAeOcMM m 

BalphurtflMid 009 


fitilpbarlc ulil 007 




fhof[ibvi1r ki'id.... .Me 


i^omboTtc Mtii on; 




Cl>toHil« »f tuilliifn . .OKI 




Oilorldeof ■hUuiii . .Mi 




AlkallWKndouUu. .011 




AUaUrasoriouUu. .114 




Olhfr tmllM 0u2 




OtlwrbodiM 014 














f 




1 




FItirin on 




W*U 107 

ChlArldoerndlDn. .4M 


KkU OH 


dtloridoorsodlnm. .001 


rt ■ 


ehlnrideorMtaM.. .Odd 
l*linapli»l« or Hill . . .Ora 


ChlorfdaorpoUua.. .048 
Humpb^i» or tad^ . . ,991 


1 


UariMHuU ofKHlk .. ,01^ 




Ou^aaftWorv'da.. .OM 


tl 


SotphMir at aoda fln| 


e 


BaliibftMofMd* «M 




rho« ll<no Mid mtg. .004 


"* 


nio& Uaw MiiA nag; .oSB 




OrMekfidphm. Iraa .4<M 




Oxide Mid pttot, trait .MIT 








OtbarbodtM TOO 


In M* tBht0 tkn mimwUi U In tba HTBlnliipoU 


la IbU talilv till OtknMkW Ib njion an« lliuuwnd I 


9»n»i sad ditrlnwl* thon-if. 


l«rf 


l» 1 



It is to bo received as a doctrine admitting no controversy, tliat or- 




16 NATURE OF UATTEB8 BECEIVED. 

ganic systems, wliethcr vegetable or animal, whetlier humble or elaboTate- 
An animal ere- {y developed, possess HO powcT of Creating matenal. Their 
tut only trans- function 13 of ncccssity limited to the mere transformation of 
foms the Bub- substances furnished to them. From this it follows, even in 

stances It re- i i i ' ^^ ■ i f i 

ceives. tlic case of man, that the substances dismissed &om the sys- 

tem arc metamorphosed forms of those which have been receiTed, and 
that, whatever their appearance may be, they must liave arisen from the 
reaction of the food, water, and air upon one another. 

This reaction we may proceed to view as a purely chemical result ; 
for, casting aside all the vain hypotheses of the older physiology, and pe> 
mitting ourselves to be guided by the harmonics of nature, we should ex- 
pect to recognize in the clianges taking place in organic systems, and in 
the phenomena which attend those clianges, the same results which arise 
in the artificial or experimental reaction of food, water, and air on each 
other. A very superficial examination of the facts shows at once the 
rhe chemical correctncss of this expectation. On such an examination we 
maitera re- ^^^ cntcr, premising it with some general remarks needfiil for 
ceived. our purposc on the nature and properties of food, water, and air. 

1st. Op Food. — No article is suitable for food except it be of a com- 
bustible nature. Its chemical constitution must be such tliat if its tem- 
perature be raised to a proper degree with a due access of atmospheric air 
it will take fire and bum, and the products of its combustion must be car- 
bonic acid gas and water, or those substances with nitrogen or its com- 

2d. Of Water. — This may be taken as tlie type and representative 
of all the various liquids used as drinks. It evaporates at any tempera- 
ture, even at those which arc lower than its freezing point, and in this 
evaporation produces cold. Water vaporizing from the skin absorbs 1114 
degrees of heat, and hence exerts a most powerful refrigerating action. 
Over saline substances there arc few bodies wliich exercise so general a 
solvent effect. In virtue of this property, it is enabled to introduce in 
tlie dissolved state sucli compounds as are wanted for the nutrition of the 
system, and in the same manner to carry away the wasted products of 
t.ecay. 

3d. Op Atsiospiieric Am. — The active principle of the air is oxygen 
gas, the effects of whicli are moderated by the presence of a large quanti- 
ty of nitrogen — four fifths of the air consisting of this latter substance. 
Physiologically, we often use the terms atmospheric air and oxygen syn- 
onymously. 

The chief materials which a living being receives from the external 
world are, therefore, combustible matter, water, oxygen gas ; and out 
of the action of these upon one another all the physical phenomena of its 
life arise. 



V&TVnB OP MATTEJIR BESTORED. 



Such being the nature and proiiortics of the things received, vrc may 
now examine in the Fame general manner those which ai^ rrupcrtirtof 
dismissed from tlic 8\'stem. Here, at llie very outset, we en- »u'w>«'kx» 

, . nil • 1- 1 1 1 ai'inu***! by 

coonter the important fact tliat they arc oxidized or bumcu Uie«ysi«Bi. 
bodies. 

l«t. As re-'spccfs the urine and its constitxients. Its liquid part, wa- 
ter, is on oxide of hydrogen, of wliicli, thongh the greater portion may 
Dot tiavQ been produced in the economy, yet a cei*tain quantity unquea- 
tionably lias. In it, too, are to be found eulphuric acid, wliich is an ox- 
ide of sulpliur; phosphoric acid, which is an oxide of phosphorus ; and its 
leading solid constituent, urea, is tlie representative of bodies wliich arise 
when processes of oxidation Iiavc been going on. 

2d. The expired and tratispired matters present similar burned com- 
[ poands. At the head of ibese products stand carbonic acid ga.% wliicli is 
[an oxide of carbon, a:id water, whicli, as wc liave already said, is an ox- 
ide of hydrogen. \Vc here omit any consideration of the nature or con- 
stitution of the faecal matter, because much of it has never Ijeen projicrly 
in the interior of the system, though it lias passed tlirough the intestine. 
Tlic general result at which we airive is, then, tliat the food consists of 
J combustible mutter, and tliat the substances dismissed from the economy 
aro oxiilizcd Iwdics. A bumiug must, then'fon*, have been go- - . , 
' ing on, and this could only Iiave been accomplished by the air occur. Ui iiic 
tutrodiiced by breathing acting upon the substance of the body *'-^* 
itself and its contents, and, to repair the waste which must have ensued* 
' a duo weight of food has been required. Since this, in its turn, as a 
of the living nieeluinii<ni, is destined to undergo the like destructive 
an, we may present the entire scries of facts under consideration cor- 
rectly by regarding tliera as arising remotely from the action of the air 
npon the food. 

With this statement before us, we next inquire what ensues when sal)- 
utanoes apjTropriale for food are exposed in artificial ex[>eriment3 at a cer- 
tain lempejatnrc to tlie action of atmosplieric air, 

A piece of tlesh, or even ot' any vegetable body, consisting of carbon, 
hydrogen, oxygen, and nitrogen, submitted to those condi- R«saiteorar(i- 
I tions, nndcrffocs combustion. Its carbon, by unitin? with ox- "^J*' oomUu*- 
Tgcn, produces carbonic acid, its liydrogen tor the most part «» ihai in tho 
water, but a residue tlieroof, combining with the nitrogen, may ^'^>'- 
I give rise to the production of ammonia. If there be any sulphur and 
I pho^>honis present, they also bum, and salts of sulphuric and phosphoric 
arids aro tlie result. 

Such is what oecura outside of the body in a common case of artificial 

tion where atmospheric air has access. The constituents of which 

15 com])oscd tiiud satisfy ihclr chemical atSnitics, and the com- 

B 



18 PRODUCTION OF HEAT. 

pounds wc have mentioned arise. Now it is a fact of the utmost signifi- 
cance that the compounds thus originating &om the direct artiiicial burn- 
ing of matters proper for food are the very same that are dismissed from 
the animal eystcm in which food has been submitted to the air introduced 
by respiration. They are such substances as carbonic acid, water, am- 
monia, sulphates and phospliatcs. 

It may impress these truths more deeply upon us to learn that the 
facts at which we have thus arrived may also be recognized in the 
changes of destruction presented by the vegetable kingdom. The leaves 
of trees, after they have fallen in autumn, quickly decay, and even the 
heart-wood itself has a limit beyond whicli it does not last. Sooner or 
later every part of a plant is destroyed by the atmospheric air. Such 
limits of duration in animal structures are short. A very brief time, per- 
liaps only a few hours, is all that is wanted for putrefaction to set in, and 
the entire mass, undergoing dissolution, is lost in the surrounding air. 

This final disappearance of all organized structures is brought about 
by the action of that energetic clement, oxygen. K by any contrivance 
its influence is prevented and its presence avoided, these clianges do not 
take place. Putrefaction and decay are slow combustions, true burnings 
taking time. TJiere equally arise from the fallen leaf and from the de- 
caying body carbonic acid, water, and ammonia, the self-same substances 
dismissed from the economy during the continxxance of life. 

Processes of combustion and processes of decay are therefore both due 
to the action of atmospheric oxygen on the changing substance. They 
differ chiefly from one another in the relative rapidity with wliich they 
are accomplished. 

The facts thus set forth warrant the following statements. The mat- 
ters which a man receives as food are combustible bodies ; tliose dismissed 
Production of from his system have been burned. To that, as to any other 
Animal heat, guch burning, oxygen gas is absolutely requisite. There is, 
therefore, a plain conclusion before us, wliich, in its far-reaching conse- 
quences, covers the whole science of physiology, and betrays to us the 
function which every animal discharges, viz., that oxidation is incessant- 
ly going on in the interior of the system througli the agency of atmos- 
pheric air introduced by the process of breathing. 

An animal, in this point of view, is an oxidizing machine, into the in- 
terior of which atmospheric air is constantly introduced. The active con- 
stituent, oxygen, satisfies its chemical affinities at the expense of those 
parts of the system which are wasting away. And as the act of breath- 
ing, that is, the introduction of this gas, takes place day and night, wak- 
ing and sleeping, so too must the production of burned bodies ; a part 
escaping by the lungs, a part by the skin, a part in the urine. To com- 
pensate the loss which ensues, nearly 1000 pounds weight of combustible 



rEODCcnos op heat. 



la 



matter mtist be nscfl in the course of a jcar, and, for reasons to he exam- 
iiiTHi in Jotail presfiitly, three tjujirtors of a ton of water. But this is a 
very diffpreiit conchisiuu to tlie notion of the ancient pliyslcinna, that an 
nnima] during its life is exempt from participating in external changes, 
and i« an enduring monument of the power posBcssed hy the VITAL POBCE 
of resisting all physical influences. 

Utit carbon by nniring vr\th oxygen can not turn into carbonic acid, 
nor can hydrogen turn into ivater, nor nitrogen into annnonia, without 
beat being produced. The very meaning ive attach to tlie ti-nn indicates 
that every process of Iraming is attended with the liberation of heat 

In domc-stic economy, we protr«i, ourselves from the cold weather of 
winter, or attain any high temperature wc want by the oxidation of some 
of the forms of carbon, mieh as wood or coal, in fire-places or stoves. 
Wc know tliat for the production of a given qnantity of heat a given 
weight of combustible matter and of air is required, and tliat by employ- 
ing various mechanical contrivances for increasing tho draught we can ac- 
coJcratc the Imniing. 

Moreover, if in onr Libomtfirifa we require the veiy highest tempera- 
ture that can be artificially obtaine<l, we resort to the burning of hydro- 
gen. There are instrumenta, such as tiic compound blow-pipe, construct- 
ed on this principle. In the flame which arises in tliis combiistion tlie 
most refractory substances melt or are deHngraleil, 

But it may be said that thougli wlicn a substance is rapidly oxid- 
izing it must be evolving heat, tliero is perhaps a slower ProdactMnof 
kintl of combination, in which the particles unite witliout any f^'iftJj," J^J** 
*Usturbance of temperature, What proof could be offered, for dec^* 
example, tliat a raooldering leaf is disengaging heat ? 

In answer to this it is not neccspary to liring forward refined or direct 
experiments. Ever>- leaf wlicn it moulders is literally burning away. 
The extrication of warmth bcfrins even when it is ready to tall. What 
does the farmer expert in making his liay, if he puts the grass up in too 
moist & fltato^ or in loo large a mass ? The temperature does not stop at 
the stage of bituminous fermentation, but the stack most probably takes 
ftfC Of course what is going on in the whole mass is going on in each 
aepttnUo leaf, undiat'mgniahablc, it is true, in the hitter case, because the 
heat of a single decaying leaf, taken alone, may lie ciirried off by the cold 
snrronnding air, or by the contact of good conducting bodic*, and so bo 
lost to exAinination. 

From ogricultural ojioratJnns we may also Icani tlinl what holds good 
for vegetahle Ixwlies is true for animal substances. Ifcaiis of manure or 
of of!kl of any kind, if due access of air be given, exhibit the extrication 
of carbonic acid, steam, and ammonia, and the temperature promptly rises. 
he gardener avails himself of this fact. He uses the heat, as it is slowly 



REGLXATION OP MEAT. 

fict IVgo bv tiic putreiaction of manure in liis forcing &amcA» to bring forth 
plants in the early spring. There is no kind of decay, or putrefaction, or 
oxidatiun of organic matters, however alow it may bo, tliat is not noarkcd 
by the production of warmth, 

ilan, in a state of health, maintains a nearly uniform temperature. 
ncBtoTiiiM): Neglecting slight variations, to be hercalter critically cxam- 
i:ac»B*e. ijiod, it ia 98 degrees. For the most jiart, it is immaterial 
in what climate of the cartli he may reside, whether in the cold polar i^ 
gions or tlie hot tropic ; he is so constituted that, cither tlirough the pro- 
visions of his own organization, or by resorting to the adventitious aid of 
clothing, or to special articles of food, he can maintain himself at abont 
tlie same degree; and as all this heat arises from interstitial oAidalion 
continually taking place, it is obvious that within certain limits he had 
control over it. Thus, in the winter he sometimes resorts to violent mii5- 
cular action in order to incniase the rapidity of respiration and tlic de* 
Btrwction of muscular tissue ; for the greater the quantity of air intn>- 
duced in a given period of time, the higlirr the tenijKraturo rises, just 
as when we close the door of a stove, or place a blower on an anthracite 
tire, an increased draught is occasioned and the quantity of heat is in- 
creased. Tu breathe with rapidity and depth is certain to raise tlie tem- 
perature. 

On the contrary, in summer, when the beat is oppressive, we instinct- 
ively abstain from muscular exertion, tranquil and slow respiration goes 
on, and tlie temperature is kept down. Again, there are means of occa- 
sioning an iiicrcHsed lilxfration of heat by changing the nature of the food 
and using highly combustible material, such as the various kiudu of alco- 
holic preparations. The clicmical constitution of alcohol is such that in 
the act of burning carbonic acid and wotcr arc pro«luccd witii tlic libera- 
tion of so much heat that chemists lind it one of the most suitable means 
of attaining a high tem[>erature. On taking preparations of this substance, 
such ns distilled liquors or wines, the first effect is (he production of a 
genial wormtli all over the body, intoxication eventually coming on oa a 
secondary result. 

These remarks are not limited in their application to our own species, 
the whole animal world furniithea us with commentuics on their truth. 
Man maintoiuing a temperature, as has been said, of about 9S degrees, 
other animals are at other degrees, some being cold-blooded and some hot. 
The particidar point the}' reach depends, as direct obsen-ation shows, on 
the fjuontity of oxj'gcn they consume, or, in other words, on their respira- 
tion. Birds, whose breathing mechanism is by far the most elaborate 
and eottcnsively devclojwd, iiave by far the highest temperature. The 
snake or tlie tortoise, whose rate of respiration is very slow, and which 
consume but little oxygen, have a coiTe8j>ondmgly low degree of heat. 



rSES or XTATEB. 



21 



I 



Um« of Wftter. 



And in those creatures whieJi at one period of the year are in full activity, 
bnt at another lie dormant or hibernate, as they begin to respire more 
slowly their tumperatiire begins to decline., and when they have Hi:nk into 
their winter's sleep their breathing is scarcely perceptible, and their 
\Tannth scarcely above that of the surroundinp; air. 

In \vhat has been thus far said wc have been coiiBiJeririg those oper- 
ations of the system wUieh tend to the production of heat, cauawofcool* 
and the maintenance of the whole mnsfi of the body at a tern- *ngof the body. 
j>eratnrc above that of the surrounding air. But it is obvious tlmt pro- 
vision must 1)6 made to prevent any imdno rise, so tliat between those 
causes of elevation and these of depression a duo. equilibrium may Iw maiii- 
tained. If a very hirgi* quantity of combustible mailer, uinler tlie form of 
food, and about an equal weight of oxygen, are necessary for obtaining a 
pm()er heat, we should also recollect tluit nearly tliree quarters of a ton of 
water are consumed each year. The duty which this water 
discharges we may next consider- 

Tlwt duty is twofold. 1st. The removal of solid material in a state 
of solution; and, 2d- The production of cold by evaporation. It is the 
coolmg Kgeney wliieh is of most interest to us in our present inquiry, but 
a few remarks as regards the removal of solid matter may not here be 
misplaced. 

Ist, Water, then, exerts its solvent power for the removal of all those 
substances which, arising incessantly in the animal system, can n* solvent 
not assume either the vaporous or gaseous state. In this con- ?<"•«•"• 
ditton an; the diH'erent saline bodies, such as the sulphates which are com- 
ing from the destruction of the nuiscular tissues, as vohmtory and invol- 
untary motions are performed ; or the phosphates which are produced by 
tiic destruction of cerebral and nervous matter. In the same condition 
vbmd nearly all the nitrogenixed results of the destruction of the soft 
parts, and which are to a great extejit to be removt^d as urea. Water dis- 
solving with more or less facility these various bodies permits their escape 
from the system by the secreting action of the kidneys, which, strain- 
ing or filtering tliem from the blood, dismiss them to the bladder, trom 
which they arc periodically rcmovetb 

Tlic skin is no inefficient anxUiary to the kidncj^ in effecting this rc- 
•al of water charged witli soluble matters. All over its suri'iicc are 
;tered in profusion the ducts of the perspiratory glands, which consist 
of a convoluted tubing abundajilly supplied with blood-vessels. The final 
mode of action of these, glands depends on extTanoDUS circumstances. 
Most ootomoidy the fluid is carried away xindcr the form of a ■\'apor or in- 
sensible perspiration, but when the secretion goes on more rapidly, or the 
dew-point of the surrounding air is high, it then accumulates as drops of 
The amount of water tiius removed, even by insensible per.^p'ira- 



?2 COOLIXO BY EVAPORATION, 

tioii, is greater llian might Ijo supposed, ypt it correqionda with the ex* 
tent of tlie provision. TIic Ieiig:th of the water-eecrettng tubing in the 
skin of a man is about twenty-eight miles. 

ThuH hy tlic action of the kidneys and the skin hirgo quantities of wa- 
ter are dismissed, either under the liquid or vaporous fonn. A third or- 
gan is roncometl in this important dtity. It is the lungs. These, how- 
ever, jinj limited in their operation to its cxlialation as ^-ajMir or steam. 
That water abundantly escapes &om them is plainly sliown when the days 
arc cold, tlie moisture as it comes tVom ihe respiratoiy passages condms- 
ing into a visible cloud when it encomitors the air. it is estimated tltat 
the loss of water by the skin and lungs conjo'uitly is about IS grains ia 
a minute, of which 1 1 piiss ofi* from tiiL* skin and 7 from tJie lungs, flak- 
ing due allowance for the variable action of tiie skin as dci>endcnt on the 
dcw-|>oint and other such causes, wc can scarcely set down the entire 
quantity at less than 1000 pounrls a y«ir. In the same period the quan- 
tity of water lost as urino may l»c taken at 900 |K>unds. It may [icrhaps 
be remarked, that here wc are assuming a loss of 1900 pounds, when the 
quantity of water nnmxally token is only loOO pounds. But it is to be 
rccolleetf^l tlmt not only does water form a very prominent constituent of 
titc solid food, whether vegetable or animal, but also that much arises 
Com the oxidation of hydrogen in the interior of the system. 

2d. "Water also c-tcrts a cooling influence, arising from its evapora- 
Cooline influ- tion from tlin surface of the skin and the cells of the iunga. 
ea« of water, "pijg ditlcrencc Ixitwecn water in the state of nn invisible var 
por and in the liquid condition consists in tliis, tlmt the vapor contains 
1114 degrees of heat which the liquid does not. When, thorefon^ it 
evaporates from a surface of any kind, as from the skin, it obtains there- 
from that lai^e amount of latent heat, and so tends to cause the tcTU|)era- 
ture to decline. Not lliat this is the only cooling agency at work. Ra:- 
diation might also bo mentioned ; for, just as a warm inorganic body cools 
by the escape of radiant heat from it, so loo does a living being. 

Tliea*! considenitiiins explain haw an eqiiiUhrium of temperature is 69- 
Ei]iitUbHnm or tablislu'd. By the process of reK|)iralion there is a constant 
beat in man. tendency to increase the heat ; but by evajiomtion of water, 
radintion, and other cooling causes, there is a constant tendency to dimin- 
ish iL A balance is struck between the two processes, and in man a 
temperature of 98 degrees ia kept up. 

This average temperature is, however, easily departed from. Through | 
some trivial cause the cooling agencies may be interfered with, and then, 
the heating proccs-'^eg getting the superiority, a high temperature or fe- 
ver comes on. Or the reverse may ensue. In Asiatic diolera, the con- 
stitution of the blood is so changed that its cells can no longer carry ox- 
ygen into the system, the heut-making processes are put a stop to, and, 

P_ J 



PHTSICAL HECHAKIflU OF MAW. 



23 



the temjicrature dcclijiliig, llie body becomes of a marble coldness cbarac- 
U'riatic of that li'rriblt! disuisc. 

The animal mechanism is thus the focus of intense chcniicftl cimngcs, 
aiitl great (|Hantitics of material aro Te<|uired in very brief Ne»«ityofr«v 
apaces of time ibr itit Kujj|)ort. AVe have seen what is the }^1'„' IJ^ u* *^'" 
use of the combastible niatt6r employed as food, what of the wasti<w. 
water, what of tJio air, how, these reacting on one anotlier, a high but reg- 
ulated temperature is kej)t up. 

Much of wlrnt lias Ijceti thus far said has liad reference only to the de- 
Ptnirtion of tissues. This waste of matter arises for a double reason, 
partly to give origin to the lieat which auimals require, and partly as a 
conse«]uonce of uitellectual activity and muscular motion ; for no movc- 
n»^nt can be made mthout a destruction of uuiseular libre, and all mental 
and nervous actions imply tiic waste of a certain quantity' of vesicular 
substance. For this reason, after an nnimal has undergone violi;nt nms- 
colar exercise, the quantity of urea and sulphuric acid in the urine is in- 
creasp<1, this being the cluinuel tlux>ugh which those results of the do- 
stniction of muscular fibre are removed ; or, after severe mental or intel- 
lectual duty, there is more phosphoric acid than usual in the urine, be- 
of the greater oxidation of phosphorus which has taken place in 
bruin. 

Hut of course ihis destruction of tissue must be compensated by a ro- 
pair if a normal condition and healtl) arc prcson-cd. Tlic action of the air 
is not directly upon the food, for intenncdiately and temporarily the \'ow\ 
is converted into the liWng mechanism. The dead material is awakened 
into life, and for a time, though only for a time, becomes a portion of the 
li\'iitg anil feeling mass. 

Tlio functions and actions we luive been considering imply the provi- 
sion of many comphcatcd mcclianisms. Tliere nui.«t Iw means y^riom mwh- 
for effecting tiie introduction of tlic air ; these, in man, dejK'nd »ni»ni» w«m«d 
on calling into operation its pressure, A system of tubes is ^^i^ ud for 
necessary for its distribution to the [»oinls at which it is re- r«i"«'r. 
qnircd. and in like niauucr a system is rc<|uirud fur carrnng away tlie 
wasted products of decay. The new material which is destined to rc- 
pUoe the parts whicli arc tlms dlsnpjxaring, and to keep the economy in 
repaiTf miut be submitted to such processes of mechanical and chemical 
preparation that it may be dissolved in the blood, and carried wherever it 
is wanteiL It must therefore be cut and cruslied by teeth driven by pow- 
erful muscles, diss(dved by acid and alkidine juices in digestive cavities 
set apart for tlmt puqiose. From these it imist he taken by armngo- 
menls which can absorb it and carry it into the torrent of the circulation. 
Physical meims must be resorted to, not only for the impidsion of these 
newly-absorbed nutritive juices^ but likewise to drive the blood in its 



24 THE SOUU 

proper career of circulation. It is needless here to dwell on the manner 
in which the most refined principles of hydraulics are brought into ^^Ajy 
or to speak of the manner in which forces of compression and elasticity 
are introduced ; how that there are valves which open only in one way 
to let the current pass, or how some of these, as in the like human con- 
trivances, are tied down in their action by cords. Moreover, since it is 
required that the animal shall go in search of its food, muscles of loco- 
motion, which act upon purely mcclianical principles on the bony skele* 
ton, must be resorted to, and so the animal structure becomes a most 
elaborate and complicated machine. 

In this regard the human body may be spoken of as a mere instrument 
PhTBical ss- or engine, which acts in accordance with the principles of me- 
pectof mao. clianical and chemical philosophy, the bones being levers, the 
blood-vessela hydraulic tubes, the soft parts generally the seats of oxida- 
tion. But if we limit our view to such a description, it presents to us 
man in a most incomplete and unworthy aspect. There animates this 
machine a self-conscious and immortal principle — ^the soul. 

Though in the most enlarged acceptation it would fall under the prov- 
Tbe Mul • 'ta *"** *^^ physiology to treat of this immortal principle, and to 
nature and re- consider its jxjwcrs and responsibilities, these constitute a 
apoiuu ties, gyi^jgpj gj Qj^f^ gQ ]x)undless and so important, that the phys- 
iologist is constrained to surrender it to the psychologist and theologian, 
and the more so since the proper and profitable treatment of it becomes 
inseparably involved with things that lie outside of his domain. 

Yet under these circumstances, considering the ever-increasing control 
which scientific truth exerts over the masses of men, considering too how 
much the welfare of the human family depends on the precision and 
soundness of its religious views, it is the duty of the physiologist, if for 
the reasons that have been specified he yields this great subject to others, 
to leave no ambiguity in the expression of the conclusion to which his 
own science brings him. Especially is it for him, whenever the oppor- 
tunity offers, to assert and to uphold the doctrine of tlie oneness, the im- 
mortality, the accountability of the soul, and to enforce those paramount 
truths with whatever evidence the structure of the body can furnish. 

For this reason, he can not recall but with regret the existing use of 
many terms, such as mind, intellect, vital principle, spirit, which, though 
they were at first doubtless employed as expressions of the functions or 
qualities of the soul, have in the course of time gathered other meanings 
and confiised the popular ideas. They have brought about a condition 
of things in science not unlike that which prevailed in theology during 
the reign of polytheism. Constrained, perhaps, himself by the necessities 
of language to use such phraseology, it is for him at the outset to leave 
no doubt of the views he entertains, and, as far as he can, prevent such 



THE VITAL PHTNCIPLE. 



25 



I 



I 



I 



I 



exfirfssKiiiB from frittering away t!»o great tnitli (lint* as tliere is hut one 
God in tilt; uni^ er»e, so there ia but one spirit in man. 

On ono of tliesc terms, the vital prineiple, 1 may make a few remarks, 
eJiicc, from 'x-iiig a mere e.\]>re8sion of eonvenienee, it lias by de- TlicriMl 
grees ri.->en among physicians and physiologists to the rank of P'"ln'^*i>I«- 
designaling an existing agent, by some reganled as of the same kind aa 
light, htail, flettrioity, or gra\-itation — nay, even gn|)erior to ihciu, since it 
is its i^eculiar attribute to hohl llicm all in check. Animated hy tliis ex- 
traordinary power, orgaiiic substances are siipiKised to withstand every 
external inttnence, and to submit To physical agents only after this prin- 
ciple haa loft them. 8ueh a preposterous doctrine will not bear the 
touch of exact science for a moment. It is oidy a relic of the old meia- 
jjjysical system of philosophizing, which accepted a name in lieu of an 
cjqdanation, which prefcrretl the dogma of the horror of a vannini to the 
more simple but material view of the pressure of the air. By the aid of 
tKis imaginary principle, complete physiological systems have been wov- 
en, in which ever)* act and every condition of the atiimal economy is spon- 
taneou^ly explainetl, and nothing remains for solution. But by the stu- 
dent of nature, whose mind Itas been trained in |>ositivQ science, tlic im- 
posture is detected. He sees at a glance that this is not the ptylc of the 
Great .Vrtist. The problems of organization are not to lie solved by em- 
pirical schemes; they reriuire the patient a])])licatiou of all imiHtrtance gf 
the aidii timt can be funiislicd by all other branches of hu- ^«"npb^^ 
man knowledge, and even then tlic solution comes tarcUIy. okgy. 
Yet there is no cause tor us to adopt those quick but visionary specula- 
tions, or to despair of giving the true explanation of all physiological 
facts. Hince it 13 given us to know our own existence, and be conscious 
of oiir own individuality, wo may rest assured that wc have wliat is in 
reality a far less wouderi'ul pfiwer, the capacity of com]>reiiending all the 
conditions of our life. (Jod has framed our understanding to grasp all 
these things. I'or my own part, 1 ha\'e no sympathy with those who 
Bay of this or tliat physiological problem, it is above our reason. ]^Iy 
faith in the power of the intellect of man is profound. Far from suppos- 
ing that (here are many things in the structure and functions of the body 
which we can never comprehend, I believe there is nothing in it that wfi 
sluill not at last explain. Then, and not till then, will man be a perfect 
monoinent of the wisdom and power of his 31aker. a created being know- 
ing his own existence, and ca|uiblc of exjilaining it. In the application 
of exact science to physiology, 1 Imik for the rise of that great and noble 
practice of medicine which, in a future age, will rival in precision the me- 
chanical engineering of my times. In it, too, are my hopes of the final 
extinction of empiricism. Kvcn now this method is attendo4l with results 
wkich most commend it to every thoughtful mind, since it ia connecting 



26 SUBDITISIOKS OF PHTBIOLOOT. 

itself with those great trutlis which concern the human family most 
closely, and is bringing into the region of physical demonstration the ex- 
istence and immortality of the soul of man, and furnishing conspicaooa 
illustrations of the attributes of God. 



CILVPTER II. 

OF FOOD. 

JTlf ttahtral Sabdicisioat of Phgtioloyy, — 0/Food: its Sovrcft catd CTattificalioH — its Valm wot 
ahorjflher dependent on its Comjtontion. — O/AtiBc: its Comjnsition, and Use of its Water, 
Casein, Stujar, Butter, and Sahs. — Variations in the Composition of MxOc. — Qf Bread. — Q^ 
mixed Diets, — Of the embryonic Food of liirds, — Nutrition of camivonms and ie rtiv arova 
Animais. — Food formed by PUints and destroyed by Animais. — L'su of tmxtd Food and Cook- 
ing. — Absolute Amount of Food. 

PHYSIOLOOT possesses n very great advantage over many other sciences 
Sabdirioionaof ^^ offering it3 leading problems and doctrines in a certain 
physiology. well-marked order or sequence, a connected whole, with only 
here and there points of digression, but those points often of very striking 
interest. Thus pursuing the train of reflections entered on in the pre- 
ceding chapter, we should have to consider the nature of the food, the 
manner of its preparation by the process of digestion, the mechanism by 
whicli it is taken up from the cavities in which it has been so prepared, 
and that by wliich it is distributed to every part. We should have to 
show the way in which it becomes incorporated as a portion of the living 
mass, its duration in that condition, and the manner of its decay. "We 
should have to show by what physical means and through what mecha- 
nism the air is introduced to effect the destruction of the dying parts, and 
how, as the consequence of this, a fixed temperature is maintained. The 
causes which lead to variations of this temperature, and the manner m 
whidi the wasted products are removed by the skin, the lungs, the kid- 
neys^ might next obtain our attention. The complicated machinery nec- 
essary to accomplish all these purposes requires to be made to act in uni- 
son in all its different parts, a condition which introduces to us the nerv- 
ous system. A consideration of the structure and gradual development 
of this system leads to the structure of tlic various organs of sense, and 
to the operations of the intellectual principle itself. Thus in succession 
we should have to treat of digestion, absorption, circulation, respiration, 
secretion, nutrition, and innervation, and to close the whole with the con- 
sideration of reproduction. This is the order which I propose to follow, 
and sliall devote this chapter to the nature and qualities of the food. 




I 
I 

I 



The snpply of food to animAls rcqwirrj* n moro compltcated provision 
tluui it docs to plants, in which the elaborating organs, the goo,^offoof| 
leaves, presenting tiieniaelvea BUpcriiciaUy, nre always in foruiiuulsuiil 
(x>ntart with tlie air, Irom which much of' their nutrition ia ^"° ' 
derived. And as one portion after another hecoinc3 exhausted. It 13 re- 
newed by simple mcclianical agencies, such as the treiiiblhig of the leaf, 
the warmth of the sun, or the winds. 

Food, iherelbre, comes spontaneously to plants, which need no powers 
of locomotion. And though, as wo shall hereafter find, muscular move- 
ment requires us its essential condilion the waste of tissue, it is not nec- 
essary lur their nutrition that plants should destroy organized substance. 
Bnt an animal must seek its foo<l, and for this purpose is endowed with 
locomotion, involving the destruction of tissue. In a chemical point of 
view, plants arc organizing, and animals destroying machines. Nor is 
this general assertion controverted by the apparent exceptions which are 
here and there presented, as, for example, that the hcrbivora can form 
sugar and fut from food in whicli those substances did not preexist, and 
the salts of the biliary acid?, which arc never found in plants. 

To obtain for animals the necessary supply of nutriment, the resources 
of nature arc displayed in the most wonderful contrivances. According 
aa their modes of lifo may be, one takes its food with its teeth, another 
with its lips, another with its fore member, another winds around it its 
whole body. The geometrical spider waves a net, and lies in wait for 
liia prey; the ant lion digs a pit in the aand. Some rely upon labor, 
some upon force, some u|>on fraud. I^lan de]}ends ujwn alL 

Viewed as r-gards its physiological distinction, the ibod is generally 
considered as of two kinds: liistogcnctic or tissue-making, and cinssificotion 
Calorifacient or heat-making, Ilistogenetic food furnishes the «f '•"»** '"'" 
chemical substances — carbon, hydrogen, oxygen, nitrogen, sul- awl calonrA- 
phar, chlorine, phosphorus, iron, potash, soda, limcH,&c Ca- *^''''"' 
lorifacient food furnishes carbon and liydrogcn mainly. In consequence 
of tills chemical constitution, tissue-making food is sometimes called ni- 
trogenized, and heat-making non-nitrogenized food. The former is also 
sometimes designated nutritive, and the latter respiratory. 

It is, howevej, to be distinctly und(!rstood that the.sc divisions arc only 
adopted for Iho sake of convenience, and that they have no natural foun- 
dation. Thus it will be found, when we examine the functions which 
the fats discharge, that though they are non-nitrogenized bodies, and are, 
tberefore, considered as belonging to the class of respiratory food, there 
is every reason to behove that they arc essentially necessary to tissue 
development, and that the metamorphoses of nitrogcnizcd bodies can 
only go on in their presence. They arc, therefore, as truly essential to 
nutrition as are the latter substances. 



I ttuu 



28 CLA8SIFXCATI03I OF FOOD. 

So, too, as respects the albnmenoid bodies, of which it would be incoiv 
lect to speak as though they were limited to nntrition. In their decay 
or descending metamorphosis in the organism, tbej give rise to the evo- 
lution of heat, and are at last dismissed under the aspect of products of 
oxidation. They are, therefore, as £eit as this goes, as much respiratoiy 
food as are the fats themselves. 

Other ciaspifi- Perhaps the most convenient subdivision of food articles 
catioasoffood. jg presented in the four following groups: 

1st. Carbohydrates, or compounds in which carbon is united with 
hydrogen and oxygen, their proportion being that for forming water. 
Starch, sugar, gum, cellulose, are examples. 

2d. Hydrocarbons. Compounds containing unoxidixed hydrogen. 
The oils, fats, and alcohol, are examples. 

3d. Albumenoid bodies. These contain nitrogen. Albumen, fibrin, 
casein, are examples. 

4th. Salts. Any classification of food articles which does not con- 
tain this group is imperfect ; for salts are not only absolutely essential 
to organic processes, but also to the construction of many tissues. As 
an example of the former case, the chloride of sodium may be mentioned ; 
and of the latter, the phosphate of lime. 

It has been supposed that the tissue-making power of any kind of 
Vaiaeorfood food depends on the quantity of nitrogen it contains, and 
doea not de- ti^t j^g value may therefore be determined by chemical anal- 

|>eDd woolly on _- 1-.., ,11 1 -■ 

itscomposi- ysis. Upou this pnnciple tables have been constructed, 
^°^' showing the agricultural worth of different articles of forage 

for domestic animals. But, as will be found hereafter, when we consider 
the physiological effect of the allotropism of bodies, these tables are not of 
the use supposed. Without entering into details at present, the case of 
gelatin may be taken as an example ; this, though a substance abounding 
in nitrogen, possesses no tissue-making value, but in reality belongs to the 
calorifacient class, and therefore its administration in the sick-room, under 
the rarious well-known forms of jellies, soups, etc, is altogether deceptive 
as regards any nutritive power, since it undergoes speedy oxidation in 
the system, and the products of its change escape by the kidneys and the 
lungs. Tlie value of food is not only dependent on the occurrence of 
certain chemical elements; they must also be present in certain allotropic 
states. 

The same remark applies to the tables which have been constructed, 
showing the amotmt of caloric furnished by different Tarieties of heat- 
making food. The quantity of heat set free during the combustion of a 
substance depends not only on the nature of the elements composing it, 
but also on the particular states in which they occur. Combustibles may 
have the same chemical composition, but very different heating power. 



COirPOSITION OP MTLK. 

Food winch 13 typically perl'ect. is presented by nalarc to the young 
of various aninuiLi. In milk, or in the egg, we should ex- iank»fi«naFti- 
' pect to find whatever ia necessary for the growtli of the tis- pif^ of rood : lu 
BueSf and lor the perfomiance of the functions. An exam- 
ination of milk will therefore illustrate the csacntial characters of the 
different elements of food. 

GtmpmalitM nf jlit &-. 

Water B73. 

CaMfa 48. 

Sugar ufmilk 44. 

Bmtcr 30. 

Pliosphaio of lime 2.90 

Otb«r »alM 2.70 

lUOO.OO 

In tlu.^ we notice, fir.st, the large proportion of water present, almost 
nine tenths of the whole amount. The double duty of this Thf water of 
water has already been mentioned, to remove from the sys- "''"*• 
tern cfitite substances wiiich are not of a vaporous or gaseoua form, and 
which can not escape through the lungs, and to regulate the temperature 
by evaporation. Wo might have added to these that it imparta a due 
6uidity to the bIoo<l. Tlicsc arc conditions ns necessary to tiic infant 
aa to the adult, and it sliould be remembered that two thirds of the 
weight of the body arc water. 

Kejct foUowfl the nitrogenized principle casein, which is closely re- 
lated in composition to muscular flcsii. It is the tissuc-mak- j|,c casein or 
iDg, lufitogenctic, or nutritive clement of tlie milk, and has been '"''^- 
elaborateU from the albumenoid substances of tlie mother's system. It 
Lt to be converted into the muscular, gelatinous, and other soft tissues of 
the infant. 

Casein is one of a group designated as tho neutral nitrogenized bodies, 
of which some of the more prominent are albumen, fibrin, xjiiar«orptx>> 
and globulin. From an opinion that these all contain tlie *^'" i**''"- 
aamc organic radical, ihcy are often tenned the protein twdics. They 
appear to exist in two diU'crcnt physical conditions, soluble and insolu- 
I Ue in water; tliey all contain sulphur, and e.\hibit a proneness to pass 
into tho putrefactive fermentation. X^ this takes place when tliey have 
reached a certain stage of decay, they act upon other bodies as femieata. 
Tlicir constitution is represented in common by the formula 

C„ H,. O.. N.. 
Of tlie whole group, albumen may be taken as the type and most import- 
ant racniber. Indeed, as will bo found hcrcancr, in the process 
of digestion tlie others are invariably converted into it. The 
white of the egg and tho scrum of the blood are usually referred to as 
oxaraples of albumen, though they ditfcr in several particukrs from one 



30 CASEm AND FIBRIN. 

another. Albumen forms basic, neutral, and acid compounds. It is a 
basic albuminate of soda which is found in the egg and in serum of 
blood. In certain diseased conditions the blood contains the neutral al- 
buminate. 

Casein presents nearly the same constitution as albumen, bat dilfen 
from it in its physical properties ; for, while a solution of albumen 
is coagulable by heat, one of casein is not, but lactic and acetic 
acids coagulate it, though they have no such effect on albumen. While, 
so far as their protein nucleus is concerned, the two substances agree in 
composition, they differ in this respect, that casein appears to contain a 
less proportion of sulphur, and no phosphorus. It is interesting to re- 
mark tliat, during incubation, casein arises from albumen in the ^gs of 
birds. 

Closely allied to albumen and casein, and having the same protein nu- 
cleus, is fibrin, which likewise exists in two states, soluble and 
insoluble. Its solidification or coagulation can be produced by 
the action of sulphuric ether, which docs not affect albumen. Moreover, 
in the coagulated state fibrin decomposes the deutoxide of hydrogen, 
but albumen does not. The most important difference between them is, 
that in the act of coagulation albumen shows no disposition to assume a 
definite structure, but fibrin docs — fibrillating, as it is termed. The 
analogy of constitution and closeness of relation of the two substances is 
demonstrated by the fact that by nitrate of potash corgulated fibrin may 
be changed into albumen, and the same conversiun is accomplished in the 
stomach by the digestive juices. 

It is generally supposed, however, that fibrin contains a larger pro- 
portion of oxygen than albumen, a conclusion which seems to be confirm- 
ed by physiological considerations respecting its origin. For this reason, 
Hulder describes it as a higher oxide of his hypothetical protein. It al- 
ways is associated with fat, or, perhaps more correctly, with soaps of 
ammonia and lime. 

Fibrin is found in the chyle, lymph, and blood. In the latter fluid 
its quantity varies in different parts of the circulation. The blood of the 
portal vein yields it in smaller proportion than that of the jugular. It is 
also affected very much by diet : thus Lchmann found that under an ani- 
mal diet there was much more fibrin in his blood than under a vegeta^ 
ble one, a result which has been confirmed by experiments on dogs. It 
has also been observed that its quantity is increased during starvation. 
But the blood of herbivorous animals contains more than that of carnivo- 
rous ones, and that of birds contains tlie most of all. 

These remarks on the composition and physical properties of casein, 
albumen, and fibrin, liave been introduced for the purpose of illustrating 
the facility with which these bodies are mutually convertible, and more 



I 



I 

I 



particiilarly lor showing that there is nothing whatever mysterious in 
the casfiii or cunl ol* milk, arising from the ulbiuninous scrum ol* the 
motlier*a bJooil, and l>cing transmuted into tlxe fibrin structure of the 
miificular tissues of tlie intaiit. 

Returning now to our exomifiatioTi of the composition of milk, as set 
fortli in the prccetling faUo, we iind that two respiratory el- tIk- »iipir and 
cments aro. next upon the list : 1st. Sugar of milk, which is ''""*"^ *''" '"'"'• 
to be convrrted into lactic acid, partly by the agency of the saliva, and 
chiefly in intestinal digestion ; 2d. IJntter, which is the oleaginous or 
fatty i>ortion, and of which a part is to be deposited in the adipose tis- 
anes for a time of need, and a part, along with the lactic acid and excess 
of sttgar, is to I»c Inimcd at oiict; for the production of heat. 

Th«^ inorganic body* phosphate of lime, is necessary for the earlhy por- 
tion of the skeleton, and probably the reason of the introduction _, , , 
of easrin, to the exclusion ot other protcm compounds, dejicnds nuik, |>iirticii- 
on the power it possesses of holding phosphate of lime in solu- |:^„^,'"n5" 
nntlo^sthaii 6 jwr cent, of its weight of thLs eiirthylwdy rhiori-Joo/Bo- 
*g ofk'M obtainable from it. Among the other salts of '""** 
the milk* chloride of sodium may be (xiintcd out as of special importance. 
It and.^riri'cs dwomjHtsition in the system of the infant, its hydrochloric 
acid giving aridity tn the gastric juice, its soda entering into the comjH)- 
BLlion of the btio and rarious salivary secretions. It also imparts sola- 
bility to nlbnmcu, and, in some degree^ regulates the facility with which 
that substance coagulates. It iji)|jci.lcs tlic coagulation of tibrin. 

J^lilk is not a chemical compound, but a variable mixture of different 
ingredients, wliich, under ]>ro|x;r circumstances, may be scpa- MnKin^of 
rated. When tlic Hniil is allowed to rest for some hours at the *>""*'"- 
ordinary temporalnrc, the fat-globules rise to the surface as cream, which, 
submitted to a strong agitatioa witb air in the process of churning, forms 
butler. 

The casein of milk can be readily coagulated by rennet (which is the 
mucous membrane of tlic stomach of the calt") at a temperature KakiHeof 
of 120^. If parted from the residual whey, mixed with a liiile •^'•*»«- 
salt and yellow colonng matter, and subjected to the action of a suitable 
|ire»s, it is formed into cheese. No better examples of the tissue-mak- 
ing and heat-making elements of food can be offered than cheese and 
butler respectively. 

When milk is exposed to the air, its sugar, under the inBuencc of the 
casein or curd, gradually disappears, laming into lactic acid, u^ip nrXi in 
and the milk becomes sour. The composition of sugar and wurmilk. 
belie acid is sucli, that we might, without much error, say that an atom 
of angar Bymmetrically bisected will yield two atoms of lactic acid. This 
It ia produced by the casein commencing to pass into a state of do- 



32 TABIOUS KINDS OF MILE. 

caj under the influence of the atmospheric air. It ia likewise produced 
daring digestion by the saliva, and also by the pancreatic juice. The 
turning sour of milk on the stomach is due to the transmutation of its 
sugar into lactic acid. 

An infant finds in its mother*& milk whatever it wants for the growth 
Pbvuioio^ncal of its own body. In its system the curd resumes the form 
tueauf mitk. of albumen, or passes into tlie condition of fibrin or syntonin, 
and in this manner its muscular and gelatinous tissues are made. The 
butter is deposited in the adipose cells, or burned at once for the pro- 
duction of animal heat, a part of it, however, being incidentally consumed, 
as will be liereafter explained, in the fabrication of fibrin and for oilier 
histogcnetic purposes. The phosphate of lime is carried to the osseous 
system, now in a state of rapid increase, and bone is formed from it. 

But though milk is so well adapted to the wants of infantile life, it is 
unsuited to the adult. Its nitrogenized principle, casein, though in suf- 
ficient quantity for the repair of muscuhu: waste and development at the 
former period, is inadequate to these purposes at the latter, when de- 
struction, arising from the incessant activity of the muscular system, is 
Varioiu kinds ®** gTcatly increased. It is interesting to remark how the 
of milk for dif- composition of milk is modified when there is a necessity to 
erentamnuu. jj^g^j these indications, its nitrogenized principle being in- 
creased in the case of animals such as tlie cow and horac, the young 
of which commence locomotion almost at birth, or at a far earher period 
than the human infant. This excess of casein is necessary for the re- 
pair of the resulting waste 

Tlte Carutittttion of Mil: 



Hource. 


C'kM-ln. 


Sugar. 


nil Iter. 




80 
C3 
32 


40 
28 
Sf! 


40 
40 
20 





This table presents an explanation of the unsuitableness wliich is 
sometimes remarked in the milk of the cow when used for the nourish- 
ment of children. Milk which is adapted to the wants of the calf is not 
adapted to the functional wants of the child. Kxperiencc lias taught the 
jiurse that these difficulties may in part be removed by diluting it with 
water and sweetening it with sugar, the effect of this being to reduce the 
percentage of the nitrogenized element, the casein, and to increase that of 
tlie respiratory, and so approximate the composition more closely to that 
of human milk. 

Moreover, milk is not suitable as the sole nourishment of adult life, 
since it does not contain in sufficient quantity those phosphorized com- 
pounds which are necessary for the repair of the waste of the cerebral and 
nervous tissues, which at this period are much more active than in infancy. 



OF BREAD. 



S3 



Variations in the compo^tlon of tniik from its normal standard are ob- 
served to depend upon age and bodily iicaltli. Young fe- Influvnceof 
males, from fifteen to twenty, yield a milk more rich in boI- IU*thJ«mS- 
ids than that which is given at thirty-five or forty. Gesta- aiUoo of miUt. 
tion at a late period increases tlie solid portions. The following table 
of Veruoiii and Beujucrcl illustrates tlie iniiucncc of disease: 



Iitjiaemx cf Diditatt m tie 0»iuf jfufioii ^ MiBe. 





Ill HomJUi. 


Amb* l»MmML 


(!hroal(! IHmfmrnr, 




B89.08 

43.04 

1.38 


884.91 

G0.40 

38.10 

29.86 

1.73 


685.50 

37.00 

43.37 

32.AT 

l..*»0 


Cuein and extractive... 




1000.00 


1000.00 


10U0.00 



From tlu3 consideration of the natmro and properties of the food of in- 
fimcy, wc may pass to the examination of that of the mature period. 

Experience has shown tliat, of all articles of food, bread made from 
wheaten flour meets best the renuirements of the adult life of 

r ..11. ' i Of bread. 

inan. It seems to contain all tliat is necessary tor support. A 

very simple analysis will show how it presents both the respiratory and 

nutritive elements. 

If Buch Hour be made into a i>aste with water, and be gradually w.x3lied 
vntii ft larger quantity, an clastic coherent mass is left, and Kxaminatfon 
the water aaaumcs a milky turbidity. After a time it bo- ^^'J"^"',^ ^ 
comes clear, tlirough the settling of a white precipitate, which otb^r graim. 
is starch, tl»c leading memljcr of the respiratory group. The elastic sub- 
stance is gluten, which is a true vegetable fibrin, mixed with another 
iiitrogcnizcd body, gltadine, wliich may be removed, along with a certain 
ijaiintity of oil, by washing with ether and alcohoL 

Thus, simply by washing in water, flour may be separated into two 
pbysiologlt'al elements, respiratory and nutritive, the former being the 
starcii, and the latter the gluten. The relative quantity of these substan- 
ces difiera in different samples of flour, and, other things being equal, the 
greater the amount of gluten the more valuable the sample, because the 
more nutritious. It is interesting to remark that the liquid from wlticlt 
the starch has settled, if brought to the boiling point, becomes turbid 
again, frc>m the coagulation of the vegetable albumen it contains. 

Otliex grains, treated in the same manner, yield similar results. The 
flour of barley and of the oat, when washed with water, do not, however, 
yield gluten, Ijut a ])ure fibrin, with a ecjmration of starch. 

The fibrin occurring in these grains is replaced in other nutritious 

I seeds, socli as peas and beans, by legumin, whicli, like the casein of milk, 

does not coagnlulo by boiling, but merely forms tenacious skins as it ia 

en^rstcd. These may be removed by skimming. This substance) 

C 



34 



OF MIXED DIETS. 



which presents many analogies to casmn, is congiUablc by acetic acid 
and alcohol, and, ii* mixed with sugar, turns curdj, and becomes sour 
from the prescnoo of lactic acid. It dithers from casein in not dissolving 
in concentrated acetic acid, and, when precipiiated by an acid, being un- 
acted on by carbonate of lime. It is, however, coagulated by rennet. 

Thus, when wc use bread made of any of the common varieties of floor, 
we tind in it both kinds of food, the respiratory and nutrilive — tlie former 
«s starch, and the latter as fibrin. 

But civilized man has greatly improved on the simple diet wluch Xa- 
t*w of butter ture furnishes, and, without knowing the imtncdiate or ])hilo- 
«n hnmd. sophical reason, has added articles which increase the respira- 
tory clement. The proverb s-iys, *' It is good to have broad, but it is 
bettcjr to iiavc bread and butter.** Let us examine why it is so. 

W'heateu flour, in its relations to the animal system, is defective in one 
point — its rc?piratorj' element, tlic starch. Xow the constitution of stan:h 
is, that in its dry state it contains much more than luilf its weight of wa- 
ter, none of its hydrogen Ijcing free, but all oxidized. It is, therefore. 
only by the use of very considerable quantities of bread th^t the nccos- 
sar^- amonnt of respiratory food can be Iwd for keeping up llie tempera- 
ture to the. proper degree But if butter he put upon the bread, the eftect 
is difierrnt. In common witli all oleaginous bodies, buttex contains an 
excess of hydrogen, and therefore, under the same weight, possesses a 
very high heating iwwcr. The detect of the flour is thus compensated, 
and by the use of quite a moderate quantity a high ten]|x;rature can be 
maintained. 

It wijuld l>e very interesting to examine in this way the physiological 
relations of the diets ailopted by communities of men, and the great 
changes wluch, at quite a recent period, liave token place llirough the in- 
troduction of tea, cofl'ee, and cliocolate on an extensive scale among civ- 
ili/.ed nations. Before tlie discovery of the ]>assago to the East by the 
Caj)e of G<xh1 Hope, and the estiihlishnient of direct commercial relations 
bct^\-een Western Europe and China, the generid diet of the ngrictdtural 
classes consisted chiefly of the common products of the iiu-ni and sub- 
Or mixed di- stances readily obtained in domestic economy, such as bread, 
chmMJ' iLpa*^ *"^ clieese. and beer. In a theoretical jwint of view, wc can 
tmr. scarcely conceive of a diet more conducive to the sustenance 

of the bodily frame. The cxjnstitution of wheat flour shows that it con- 
tains tlic elements necessary fur liic ; and diccsc, which may be regarded 
as the preser\'od curd of milk, is an excellent flesh-producing body, the 
casein of which it consists being readily couverriblc into musclc-fibriii. 
The common salt nscd in its preiiaration promotes the function of diges* 
tion, by furnishing hydrochloric acid and soda. In addition, tlierc are 
also in the bcor, an alcoholic and intoxicating liquid, all the advantages 



1 



EMBRYONIC FOOD OF BUtDS. 



of a highly comhusliWc body for tlio pttrposes of respiration- Whatever, 
therefore, is requisite for the well-being of the animal economy is present 
in abundancti in such a diet. 

From an examination of the diet-scales of the educational and invalid 
establishments of London, the prisons and tlie hospitals, Benek6 obtains 
the result that the nitrogenizcd shotdd be to the non-nitmgcnizcd food in 
weight as one to five. Krom other data, Frerichs ealculatcs fiatioof nitro* 
that llie diurnal consumption should be 2.17 oz. avoirdupois non"^?,^™. 
of nitrogenizcd, and 15.54 02. avoirdupois of non-nitrogen- iMJfood. 
izcd food, that i.s, about as one to seven. Whatever is taken more than 
this is sttperHuous. 

The peculiar advantages arising from the use of casein, whieh in a solu- 
Wc form possesses the qualitj* of disBolving large quantities of phosphate 
of lime, unquestionably determine its employment as a constituent of 
milk. Bat there are circumstances under which a necessity arises for 
the use of other nitrngonized compound.^ such as albumen, in early nu- 
trition ; and then it is rcnmrkablc by what indirect methods the difficulty 
of its want of solvent power over tliat earthy body is ccmpcnaated for. 
The faiUd period of the life of bu^ds fiu-niahes an example. In the egg 
(here is, of course, whatever is wanted for the devfiopment Development 
of the young animal; for, merely by the process of inculia- jJ^„^oririn 
tion, or submitting the egg to a due tcmpemture for a suita- wfiu puts, 
ble Icjigth of time, with the access of atmospheric air, the young chicken 
forms, with all its parts complete — its bony, muscular, nervous systems, 
feathers, beak, claws. Tlie phosphntc of lime required for the skeleton 
is not present as audi, but is formed as incubation goes on ; for in the 
yolk there is free phosphorus, to which the air tinds access through the 
pcr\'ioaH shell, and, effecting its oxidation, phosphoric acid is the result. 
This reacts on the carbonate of lime, of which the shell consists, decom- 
poses it, and the phosphate of lime forms. For this reason we obscr^'e, 
OS the incubation proceeds, that the shell becomes lighter and thinner. 
The albuminous iluid which constitutes the wliite of the egg has little 
power of liolding bone-earth in solution ; but by manufacturing the salt 
in this manner, as it is wanted, the development of the young bird goes 
on without ditHculty. To insure the due supply of oxygen, an air-bub- 
ble Is placed at the broad end of tlie e^Q^ so that, slionid any transient 
ctrcumstancc inteifere with the passage of air through the pores of the 
■holl, there is a little reservoir of that material on which to rely. 

The mammalia find in milk all lliat they need in their infantile life 
for Ihwr nutritive purposes. In the same manner birds, in their foetal 
life, have whatever they require in the egg. For the former, casein is 
the nutritive element; for the latter, albumen. In both cases a ready 
transiDutation of that clement into muscle-fibrin occurs. 




i 






At A matarer period of life, animals may he divided into two groaps, 
carnivorous and herbivorous, or those which feed exclusively on flosb, 
and iliose wliich feed on vcgetalile salistanoes. IJctween these may, 
perhaps, be introduced a minor group, partaking of tlie manner of lite of 
both. 

The comivoroas animal Bnds in its prey nil that is required for nu 
Kntriiion of ^*"^ ^^^ *^^* discliargc of its functions. Digestion nnder thcW 
cBmiroroiu circiunstances is reduced to its simplest conditions, and is 
scarcely more than a process of solation. In the stomach the 
fibrin is brought into a soluble form ; in the duodenum the fats arc re- 
duced to an emulsion. The digestive apjMuratus lias l)ut little complexi- 
ty. The stomach may 1)c regarded as a mere enlargement or pouch npon 
the alimentary canal, having, along witli the intestine, the office of biing^^ 
ing the food into such a condition that it can Ihj taken up by the \'eini^| 
and lactcals, and so pass into tlie circulation. The various constituents 
now revert into the same stale in which thoy were before digetition be- 
gan, the fibrin aiding in the repair of the wasted muscular tissues, and 
the fats being deposited in the adipose cells. Tlic bone^, feathers, and 
other such matters as have not been dissolved by digestion, are cast out 

In the production of heat and motion the carnivorous animal consamca 
itself, and, through the oxidation incessantly going on by means of the 
air introduced by respiration, carbonic acid, ammonia, water, snlpharic 
and phosphoric acids are constantly forming. 

On a superficial view it might be supposed that in the other gron 
Nairition of ^^^ herbivorous, the case is quite different. These Bcem tfl" 
)i«rbivoroua Spend all their lives in obtaining food. 1'ho ox or the horse, 
"'" put out into the pastures, is all the day long cropping the 

grass. On a comparison of the qxiality and nature of the food which 
they take with tlie substances of which their bodies consist, tlicrc secma 
to be nothing in common. It was not, therefore, without reason tJiat the 
earlier jthyHidlogiHtH !ni])uted to the digestive organs of this class the 
power of fumiing tlcjdi and blood from vegetable matters. When, how- 
ever, wc come to n critical examination of the facts, we find that there is 
no essential difference between them and the carnivora. 

When the expressed juice of vegetables is permitted to stand for a 
t'mie, though it may have been dear at first, a turbidity sets in, and a flaky 
material is dc|K)sitcd. The substance thus jwsscssing the jmwer of spon- 
taneous coagulation is identical in tliat property, and in composition, with 
animal fibrin. After its deposit, if the clear liquid bo warmed to near the 
boiling point, it again becomes turbid, and a second nitrogenized sulv 
stance subsides, wlueli, from its quality of coagulating by rise of tempera- 
ture and its analysis, is inferred to be identical with animal albumen. 
When this has been separated by filtration or otherwise, and the juice is 



wuTRinyr mattebs rnE-Exisr in plants. 

slowly evaporated, ihere come on its surface skins ot' a body having the 
eanic qualities as casein ; so fibrin, albumen, and casein pre-exist in plants. 

Fatty matters of every description may also be extracted from vege- 
table products. From leaves, seeds, bark, wood, etc., oleaginous bodies 
can be obtained by the action of sulphuric ether, which removes the fat, 
and leaves it on subsequent evaporation. 

It being thus understood that the food of the graminivorous animals 
contains nitrogcnized bodies and fats ready formed, we have clearer views 
of the function of digcstiou in those tribes. It is not necessary to im- 
■ pate to tbeir digestive organs the power of creating ficsh and fat from 
vegetable matter. The office of the animal is merely to collect. The 
two groups being compared together, the carnivorous animal receives uq- 
der less compass the required amount of nutrition, and its digestive ap- 
paratus is more compact. But the graminivorous animal must all tho 
daylong collect large quantities of food, out ofwliich it may extract tho 
little nutrient matter they contain. The carcass of an animal, seized by 
a lion« is almost all digestible, but it would require a very large amount 
of herbage or of grain to be supplied to an ox to make up tfic same (quan- 
tity of albumen or fat. Hence the necessary complexity and size of the 
digestive organs of the herbivorous group, and hence many of their hab- 
its of life. 

Horeorcr, we see that even in tliis apparently extreme case the ani- 
mal system does not clearly exhibit any quality of exerting Foodfonned 
a formative action, nor of grouping atoms into a state of d'^{^v"'JJ,y 
higher organization. It {msscsscs no special power of mak- uiiuiaifl. 
ing flcah. To the vegetable world we have to look as tiie great forma- 
tive agent. In the organism of plants the various compounds wanted 
by animals arc fabricated. Animals destroy those compounds, and In 
so doing maintain a high temjieraturc, irrespective of atmospheric con- 
ditions, and give rise to the phenomena of motion and intellectuality. 

Universal experience, as well as direct experiment, proves that in the 
case of man health can not be maintained on a uniform diet, however it 
may be with animals. A mixed food, wlitch varies from time to time, 
Beems to bo essctilial ; and tlicre can not be a doubt that the cltanges 
which physicians have recognized in the naturc of the predominating dis^ 
eJuies, from century to centurj', arc connected with changes which have 
taken place in the naturc of tlie diet. Tiio introduction of tea, coiTee, 
tho potatoe, and tobacco, must have made a marked impression in these 
respectB. 

Undue oxcesscs of albumen, oil, or starch, in tlie diet of an individual, 
produce a liabiUty to arthritic, bilious, and rheumatic aifco- Kccowiirof a 
liooa. An abstinence from fresh vegetables and fruits dcvel- ".n'^.Ja'iJ^ 

I Boorbutic, and a deficiency of oleaginous materials scrofu- ufouokiu^'. 



QMBCOTbU 



ABSOLUTE QUAXXmr OF FOOD. 






Ions disease It i& evidctit that a control over thc£e affections may be ob- 
tained, or even their cure, to a considerable extent, accompliabed* by suit- 
able changes in the nature of tlic food. This is strltuugly seen in the 
imjirovemcnt of the liealth of sailors during long voyages, since the intro- 
duction of vegetable preparations or acid juices. In 1726, Admiral Ho- 
sier sailed from England to the West Indies with seven ships of the 
line, and lost his whole crew twice by scur^-y. The circumnavigation 
of the globe is now often accomplished withoni the loss of a single man. 

I have already remarked llie insufficiency of the tables setting forth 
the value of articles of food as dependent on their chemical constitution. 
Such tables are of little use, agriculturally, in the case of animals, and 
still less, physiologically, in the case of man. The art of cooking does 
not minister alone to the grati&cution of the palate, it lends a real assist- 
ance to the opcnttion of digestion. New elements may not have been 
added, nor existing ones removed in submitting the food to the action 
of a high temperature, yet such a change is thereby impressed upon it 
that it becomes more capable of digestion, and raoro subservient to the 
wants of the economy. 

In determining tlio absolute quantities of nutrient substances rcqu 
Tl»«»»oliiw ^y *^'® '*y8*^"'» Lchmann observes that there arc three 
quotiijr «f nitudes wliich we arc especially called upon to consider : the 
first is, the quantity of food requisite to prevent the animal 
sinking from starvation ; the second is, that which atibrds the right sup- 
ply of nourishment for the perfect accomplishment of the timctions; and 
the last is, that which indicates the atnouiit of nutrient matter which 
may, under the most favorable circumstances, be subjected to metamor- 
phosis in the blood. The method of finding the minimum of food nec- 
essary to support life by stopping all supplies without, and determining 
the quantities of matters which ihc organism \iscs by the excretion of 
urine, faeces, expired and transpired products, though it has yielded re- 
sults of the utmost importance to science, ia nevertheless not altogether 
reliable, for in such a state of inanition the 8y»tem is hrougltt into a 
morbid condition, or, at all events, is not acting in a normal way. More- 
over, much de|iends on tlic activity with which the various functions are 
carried forward, a necessity for nourishment increasing with increase of 
external activity. And as to the amount of food demanded for tho 
maintenance of the system at its standard, it must be borne in mind 
tiiat of the four classes, the carbohydrates, the fata, the albuminous mat- 
ters, and the salts, no one alone will answer the purpose, but all must 
be employed together, and this in variable proportion, according as the 
local, and tlierefore variable, wastes of tho system may have been. These 
considerations indicate how complicated the problem we have in view 
really is. 



QUJINTITY OF FOOD BEQCIBED. 



39 



From the* oxpcriinciita of Botissingaull wUli reference to fat, and of 
BitUlcr nnd (ScitmiiU witli reference to tlie ulliuminates, and Maximiirn lim. 
of Yon Becker with reference to the carboliydrptcs, wc learn Jil'rJw;;?','^; 
only definite (]uantitics of tlie^o substances can be ab- mcLUoffood. 
ibcd by tl«^ iitte.stine in definite jjeriods of time. Tbis niaxlinum limit 
is, however, iai more tiian the nccc^itics of the system require ; hence in 
overfeeding, thongh much of the excels of food passes awny with the cx- 
ctcment, a very large portion i?, as it were, needlessly absorbed, and, un- 
dergoing inetamor{ihosis in the blood, is removed by the kidneys. To 
ihb* portion Ijchmann applies the designation introduced by Schmidt^ 
Iu2lUb cou5nmption, or su]]crfiuouB consumption. Of course^ the simple?! 
condition under which wo can investigate the normal quantity of food 
required is that of an invariable weight, imd the difficultiea of the inquiry 
arc increased when growth, corpulence, pregnancy, or other such states, 
arc included. 

Though we arc very far from being able to olTcr a complete solution 
of the problem of the amount of food required, in its most general sense, 
^•et, through the labors of many chemists, we have accumulate*! several 
filers wliich have a bearing on this queatioiu Thus it Is knowTi that albu- 
mioous substances alone can not be absorbed in quantity cnougli to com- 
penaatc for the loss of carbon by respiration. A duck, as is shown by 
Boossinganl I, exj)inw in one lioiir l.S.O grammes of (airlmn, but cm only 
absorb of carbon iujdlmminulcs 1.00 gramme. So, in like manner, lat nlonc 
ia inadequate, for of tliis substjmcc U.84 gramme, containing about 0.70 
gnmuiie of carbon, can only bo taken up in an hour, and this is not much 
more than half of what the respiratory operation demands. Tlie carbo- 
hydrates, however, can l>o absorbed in sutficieut projmrtion, and in this 
nujced manner ore all tlie requirements satisfied. Boussingault makes 
the cnrlnus remark that, in the quantity of starch, 5.20 parts, and the 
quantity of sugar, 5.62 parts, which this bird can absorb in one hour, 
there arc nearly the same quantities, 2.37, of carlwn. 

Among the specinl investigations which have been made to determine 
the amount of food used and the amount of oducts from the j^jntmntot 
ajvtcm, should be mentioned that of Valentin upon himself, f'^^. "'"i 
His weight was 117 lbs.; his diurnal consumption of food, 
C.'i^I lbs.; solid excren^ent, .42 lb.; urine, 4.G8G lbs.; and 2.751 Ibe. 
perspiration. From the more recent and very exact experimental of Bar- 
nl^ it is inferred that of 100 grammes of carlion which have been ab- 
sorbed into the organism, 91, .51* escape as carbonic acid through the lungs 
and skin, 458 appear in the urine, and 3.83 arc re-cjccretcd and appear 
in the fa>c(^ Upon similar principles, Lchmnnn computes, trom the 
data furnished by Burral, that for every 100 jwrts of absorbed nitrogen, 
■iO.G ports are removed through the skiu and lungs, 42.07 arc found in 



■mount of lou. 



40 OF DIOESnOX. 

the urine, and 8.33 are re-excreted into the fieces. As a general resnlt, 
it follows, from these experiments, that an adult man oxidizes, on an 
average, 289 grammes of carbon, and 18.6 grammea of hjdrc^en in 
twenty-four hours. 



CILVPTER IIL 

or DIGESTION. 

TiaBUB-MAXIMa OB HISTOOSmTIC DlOXSnOV. 

Natvrt of Digestion.— TU Mavtk, 7>rfA, Stamadi.— The SaBeary GlimdM.—Differmt KM» tf 
SaBra. — Pny)«rtiet of mtsed Sa&ra : it* Qinatitjf, CbmpontioR^ <md Fimetiam*. — Sek^am af 
the Salivaty Gland* md Kidney*.— TKe diffettivt Tract. — 7^ StomaeL — Gattric Jaiee.— 
Organ* far it* Preparation. — Manner of producing Chyme. — Injtmence <^ tim Nerve*. — Arti/i' 
riai £)ige*tiom. — J'reparation and Propertie* of I^rpttn. — Regiomai and/ioKtiomal Divitiom* of 
the Stomach in Animaia and in Man. — Object ofStomaek iMgettion, — Peptoma, — Uae ofSak. 
— Dige*tibi&ty of varum* Articia of Food. 

Before the food can be absorbed and carried to all parts of the sys- 
Xatara of tem it most be submitted to certain preparatoiy operations. 
digeatioo. ginco it IS either to be dissolved in the blood or transported as 
chyle through the lacteal vessels, it is absolutely necessary to bring it 
into a condition of solution in water, or at least into a state of minute 
suspension in that liquid. Received in masses of a certain size, it is 
first cut and crushed into smaller portions by the teeth, and then bronght 
from an insoluble into a soluble or suspended state by the chemical ac- 
tion of the digestive juices. 

In the mouth the food is submitted to a twofold preparation. It is 
Fanctions of divided by the mechanical action of the teeth, and also simul- 
tba mouth, tancously mingled with liquids secreted from the salivary 
glands. 

The animal series present us with numberless contrivances for accom- 
plishing this comminution. The teeth, though of a bony nature, are not 
to be regarded as appertaining to the skeleton, but rather to the digestive 
mechanism. Their structure, number, and position differ very much in 
different tribes. In certain fishes the mouth is almost lined with them. 
In crabs they extend to the stomach, but in other cases they are restrict- 
ed to the pharynx, or are wholly absent ; this being the case, for instance, 
among the ant-«at«rs. Those insects whose food is of a fluid nature have 
iDstmineiitsof no need of teeth ; but those which use solid material are ao- 
commination commodated with suitable instruments of abrasion, such as 
mila. borers, chisels, saws, nippers, the particular mechanism re- 



THE TEETH. 



I 
I 



jn^t 



Kortod to being adapted to tlie nnturc of the food. It is to he undersiooJ 
that these Tneclinnical terms arc not mere metapliors, tlioy indicate the 
actUAl nature of the apparatus. The object aimed at is to obtain the food 
in such small portions, and in such a bruised or pulpy condition, that di- 
gestion can be accomplished promptly. In man tlie number of 
temporary teeth is twenty^ ten in each jaw. They arc arranged 
in llircc dosses — four incisors, two canines, and four molars for tlie up- 
per and under jaw respectively. The permanent teeth, which are eventu- 
ally substituted for these temporary ones, arc thirty-two in number, elass- 

iticd lor each jaw as four incisors, two ca- 
nines, four bicuspids, and six molars. 
Their arrangement is exemplified in J*iff^ 
1, representing the lower jaw, in which 

L^^ftb^^^KJL i is the middle and lateral incisor, <* tho 

'vj^^^nWB32l'5'"Tl^s canine, b tho two bicuspids, and ?n tho 
m^fkhBt^f^fjlM' three molars. 
^JM^^^E^^^riU^K The movements of the teeth, aided by 

^^^^C^^^2S!^^^ those of the tongue, accomplish a due 
^^^^^^^^^ abrasion of the food, and Bimultancouslr 
The liiiiuau lowor j««, . • - i i i- rm • - 

incorporate it with tlie saUva. Xlus is, 
tbereferCt a purely mechanical operation. It is analogous to Mpf|,on[e„in». 
the methods to whicli chemists resort in their laboratories t<ir«urmutjc«- 

Ptrhen thev prepare sohd materials for os|>osurc to reagents. 
The mingling of food witii saliva, or inaalivation, eflects a double ob- 
ject. Coated over with a glairy juice, the bruised substance passes 
k along the oirsophageal tube into the stomach ; but there are also certain 
p cbcoiical changes, wliieli, commencing in the mouth, ore of essential im- 
portance to the completion of digestion. 

The stomacli is an ejcpansion of the alimentary canal between the 
tBSOphflgna and duodenum, of a conical figure^ the base of p^^rjpji^^n gg 
wkiv^ is to the left. It communicates with the a?Bophagus ibc huinnu 
by ita cardiac orifice, and by its pyloric with the duodenum. "'""* • 
It conwsta of three coats or tunics — the serous or peritoneal, which is 
exterior ; the muscular, which is intermediate ; and the mucous, which is 
interior. They are connected with oacli other by cellular tissue. The 
^ fibres of the muscular coat nin in tlirec difierent directions, constituting 
H time layers; the superficial ones arclongitudinal,radiatingfrom the oesoph- 
H agOA over the surface of the organ ; those of the middle layer arc circular, 
" or ring-like ; they are well developed about the middle of the stomach, 
and by their contractions sometimes make it assume a divided appear- 
ance, OS tbongh composed of two compartments. Toward the pylorus 
ihey are also grcallv" rcscnforced. The fibres of the thinl layer take, for 
tba most part, au obUque direction. The interior or mucous coat is some- 



42 



THE 8T01UCH. 



tetlon of tht kiutuia MomiMb ■ikvvuig tu muwu* latsrtoe. 



lime.<i tpriued the tHIous, from its Tclvctjr appearance. Its color U rtxf 
variable; it is folded into nigip, which admit of vnriationa in the disten- 
tion of tlie slonioch, withoat intcrtVrcncc with tlie stmctuic or functions 
of the membranes of which they arc u part. The cardiac oriiict.' is pli- 
cated, and the opening into the duodenam is through a circular fold with 
a cenfnil n|K;rtuK' — tlie pyloric valve, which being sunoanded wiih a 
band of muscular Hbrca, acting aa a sphincter, the passage from the etom- 
och to the intestine may be entirely obstructed. 

The stomach is socn in 
section /ly. 2, a being the 
oesopliagns; ^ the greater 
extremity ; c, the smaller 
curraturc; d^ tlic great 
curvature; e, the pyloric 
or less end; /", A, the du- 
odenum ; ff, place of entrj* 
of the ductus commums 
choledochus and pancre- 
atic duct. The place of 
junction of the asopbagus 
is the cardiac rc^n: the 
membrane is there plicated. Tlic place of junction of the dnodcnum is 
the pyloric region. 

The tyj>ieal form of the digestive apparatus is a sac with one aperture, 
IWtorUie which pcr\'c« the double purpose of affording an rntranee to 
•loDitch. nutritive material, and an outlet to uudigCitted renmins. In a 
liighcT condition it may be conceived of as a tube open at both ends, and 
having n sac-like swelling on its middle pari. The portion of the tube 
anterior to the sac ia the ty]ie of the cesophagus, its ajxrtuTc answering 
to the mouth, the sac-like swelling being the type of the stomacli, and the 
tuljc leading from it representing the intestinal canal. In the more elfr- 
meutary of such fonns, vessels arise from the walls of the digestive cav- 
ity, and pass to all other parts of the system. These 8er\e to convey the 
elaborated materiul. Certain a]>ix'ndagcs are soon to be discovered in 
comiection with tliis simple digestive mechanism. They arc lor the 
preparation of salivary, gastric, pancreatic, or biliary juices. In size or 
development they vary with tlie habitn of life of the animal, or with the 
nature of its food. Indeed, the same remark may be made as respects 
the entire digestive tract of the highest tribes. Thus, in the bat the 
length of the uitestino is to tliat of the body as three to one, but in the 
sheep OS twenty-eight to one. The ruminants generally have an intes- 
tinal tube of great length. In man and in monkeys the proportion is 
about tive or six to one. Again, as regards construction, there are many 



> 



DTFPERENT KINDS OP SALTVA. 



43 



diversities, the numljcr of digeativc dilatations an J their size corre8|)oml- 
iog in some measure to the nature of The food. 

Thn'c pairs of glands, the parotid, submaxillary, and sublingual, so- 
crclc saliva. Of these orgiuis tlic parotid is the largest; its nifff-rentkindi 
Mcrction w dclirered tlirough the duct of Stcno. The sub- of "!''•«■ 
m&xitlnry durt is Wharton's, but the sublingual pours its iluid t]ux)ugh 
many smali apertures near the frenum lingua:. Besides (hew proper sali- 
xnA, the lining membrane of the mouth yields a fluid, tlie buccal mucus. 

The parotid saliva L* tliiii and watery, limpid and colorless, inodorous 
and tasteless. Secreted during fa^^ting or under the use of Tb^paraUdH* 
stifnulatin<; food, it is denser. It contains so laige a quanti- •'^'•■ 
ty of lime that, on exposure to the air, it becomes covered with an in- 
crustation of the carbonate of that substance It also contains sulpho- 
cyniiide of potassium. Its organic ingredient, if not olbamiuatc of soda, 
closely resGUibica that body. 

From the chemical constitution of the saliva of the parotids, the phys- 
iological function of tho.se glands, as ar[tiijKUY)uii organs, is estabhshcd. 
Thqr yield a certain quantity of watcrj' juici\ ivliich, by reason of its 
tfahmess or fluidity, is readily incorporated with the food by the teeth. 
Parotid saliva appears to have no power of transmuting starch into sugar. 

The subnia-xillar)' sahva is also colorless and lunpid, tasteless and in- 
odorous. It contains no morphological elements. It is xhc lutimaxtl- 
lightcrthan the parotid, leas alkaline, and contains less lime. IwynJivn. 
For this reason, when exjMised to tlie air, it docs not become incnisted 
with carbonate of tliat earth. It contains sulphocyanidc of potassium. 
It is so viscid and glutinous that it may bo drawn into threads. From 
thi» physical property it probably facilitates deglutition by furnishing a 
kind of anti-friction coating. 

Thft sublingual saliva is thin and water}', containing, like the parotid, 
but a small percentage of solid matter, and probably dis- riie faWlnguil 
charging a similar function. mUv*. 

I Besides the special salivary juices, the lining membrane of the mouth 
pours forth a liquid — tlie buccal mucus — a thick and tcna- The buccal nnu 
ciouB substance, having many citithcUal cells. It is alkaline <=•"• 
in its reaction, docs not coagulate on heating, its insoluble salts contain- 
ing no carbonate of Ume- It lias l>cen obtained for examination liy tying 
the ducts of Stcno and \Miarton, keeping tlie nostrils o^ien and tlie head 
inclined, so lliat, the animal being unable to swallow, the mucus tlows out 
of the mouth. 

The buccal mucus, if mixed witli parotid saliva, does not appear to 
possess the power of turning starch into sugar, but, if mixed with tlie 
flubnuudlUry accretion, it accomplishes that transmutation with facility. 

The aaliva, as obtained from the mouth, is therefore a mixture of tlio 



■ 



ficcretiona of tbe various salivarr glands. It may be doubted whetlia 
propertiFtor the method of obtaining it sometimes recommended, bv mak- 
mUcd uUvu. jjjg pressure under the cliin and tickling the £iaoea with a 
feather, jHelds it of normal amstitntion. It is de.scribcd as an alkaline 
jaicc, of .1 bluish color or colorless, in consistency glairy, readily frolh- 
ii^, and therefurc well adapted fur entrapping atmospheric air. It con* 
tains, of solid matter, from 0.<^<S to 0.841 [>er cent. h» alkali appears, 
for the most part, to be combined willi an organic substance, ptyaline, 
from which it may l>e separated by the weakest acids, such as carbonic. 
In the Rsh of saliva the alkali oeeura chiefly as phosphate: this arises from 
rearrangement of the constituents during incineration. The saliva con- 
tains but a trace of alkal'me sulphates, the chlorides of soditmi and potas- 
sium prepondexating over all the otlicr mineral ingretlients. 

On standing, saliva separates into two layers : a transparent one^ which 
is supernatant, and a grayish turbid one below, which consists of a de- 
posit of particles of pavement epitheliimi and mucus corpuscles, derived 
from the lining membrane of the moutli and tbe sativaiy ducts. Its 
clicmical reaction varies to some extent with the state of the system ; thus, 
after long-continued lasting, from being aikahnc, it may approach tlie ncu- 
tnd state. By some it is a5sertc<l that under these conditions it may 
even become acid. There is no proof tliat this is owing to the appear- 
ance of lactic acid : it may be due to butyric acid, or even the acid phos- 
pliate of soda. In morbid conditions llus reaction is by no means infre- 
quent: it has Iteen commonly oljser>'ed in inteslinnl iutlnmmation, acute 
rheumatism, intermittent fever. Donno and Frerichs assert that acidity 
of the saliva depends on an irritation of the buccal mucous membrane. 

The specific gravity of mixed saliva varies from 1.004 to 1.009, , These 
variations depend on many different causes, there being a diminution after 
Ihc taking of drink, and a greater increase after taking tbod, than even is 
observed in the fasting state. An animal diet especially increases it. 

Under ordinary circumstances, the saliva is secreted to an amonnt of 
Qu»niliy of from 15 to 20 ounces daily. TIic exuilation is more copious 
nllvB. during ranstieation, sjx'aking, reading, more being produced by 

the use of hard than soft food. Mental emotions exert a control over its 
flow, sometimes diminishing it, as in momcjits of anxiety, sometimes in- 
crwiising it, as by the anticipation of food. After eating, the flow contin- 
ues to a considerable extent ; it is also provoked by the use of aromatics. 
On irritation of the interior of the stomach through a gastric fhstula, the 
flow is simultaneous with that of tlie gastric juice. 

TIic movements of the jaw and the pressure of the food give rise to va- 
riations in the quantity of saliva. It is perhaps for these reasons that the 
jiarotid gland on that side of the month which is most used in masticition 
secretes more than the other. Of the proportion of the different kinds <rf 



coxsTrrmov op baltta. 46 

[salira in the mixed secroiion, nothing is known witli certuinty in the case 
of marif but it is said that in horses tlie parotids fiimifih two thirds, the 
enbniaxiUaries one twentieth, and the sublinguaU and mucous folHcles 
the rest. The secretion of the saliva goes on during Bleep. 

To the acti^'e organic nubatoncc of the saliva the designation of plya- 
line has been given. It is regarded as a ferment, possessing in 
BCTcral respects the properties of diastase, and hence has }xcn. 
called by Mialhe diastase salivaire. 

For the ]>urpose of analysis, saliva should be obtained in a perfectly 
fresh state^ a condition not easily fulfilled, for it decomposes or changes 
with rapidity. 

During these cliangcs, alkaline carbonates, for example, are formed in 
abundance, though they may have existed hut to a small extent at first. 
We have already seen that in tliis way parotid saliva, ex- Connitatloo uf 
posed to the air, yields crystals of carbonate of Unic, The ►»!'*»- 
following tabic is presented as offering an example of the average consti- 
tution of mixed saliva. 

Owatittaknii/' tit SaKea (/VeWrA*), 

Wiuer 9M.10 

Kpiihelium fto<l mneos 2.18 

Fat .07 

Ph'alino ntiil alt'tiliul extract 1.41 

SulphocyniiiJo of potassium 10 

Fixed salt* 3.19 

lUUO.OO 

Of the fixed aalts the chief are, the phoisphatcs of soda, lime, and mag* 
ncaia, and tl»e chlorides of sodium ond potassium. The sulphocvojude 
of potassium vanes in amount considcraLily : it increases after meals, and 
especially after the use of condiments, salt, pepper, spices. Those arti- 
cles whidi contain sulphur, as mustard, garlic, radishes, increase its amount 
in a vciy marked manner. 
I Not only does the wdiva, as derived from the different glands, present 
differencefl of constitution ; it likcwij^c differs in various ani- Modifitation* 
mals, and in the same animal according to its age. This is "' wJiva. 
observed eveji m the case of man. The saliva of an infant at the breast 
poMcases very litlle power of saccharizing starch, a transmutiition which 
tiiAt of tlie ajlult accomplishes with energy. 

The action of this secretion appears to be limited to starch, and certain 
j kinds of sngar, whicli first yield lactic and then butyric acid. It does not 
f exert any influence in transforming albnminons matter. 

The saliva discharges many functions. It is a necessary intermedium 
in the ncnse of taste, for substances to be sapid must be more punctltmi of 
or less soluble in this juice. If Insoluble, they are tasteless, •■li'^"- 
It aIbo moistens the interior of the mouth, and prevents the sensation of 



46 



8AUVART DI0E8T10M IN THE STOSIACH, 



I 




dryneps. But its chief duty seems to te tliat of protnotini^ the digestif 
opcratiou ; for, though the food remains m the mouth but a short time, 
the action of die saliva is prolonged after the masticated mass haa been 
depoi^itcd in the stomacli. Though the direct admixture of saliva with 
gastric jnicc injure? the }K)wcr of the latter, this effect doea not ensuo in 
the stomach, since thoy act for the most part separately. The action of 
the gastric juice is snpcrticiiU, and two distinct operations arc ihen^rr 
conducted at tlw suitie moment, the surface of the food duinging undw 
Action of tfao the influence of the gastric juice, and the irmer portion \uh\ct 
Unuwl'iii^c ^"* of the saliva. I hcUe%'0 that in this manner the saliiin- 
Monad). juice Icnds itself to stomach digestion, for it is well knouii 
llmt by its aid starch chxmges into gTa|ic sugar, and the transmutation 
does not stop at tliat point, but goc-s on to the production of luetic acid.. 
An acid juice is essential to stomach digestion. 

After the ad ministration of halls of starch to nniraals in which 
Pmlo^lon of fistulas liave been established, sugar may be detected in 
mtgmrTrxtm gfomach in thc course of ten or tiftcen minutes. It docs 
■tomnchhyLha uot nppcar that there is any relotion between the quantity 
■*^''*- of saliva incorporated by mastication and llie quantity of 

starch la the food. Animals which swallow their food without mastica- 
tion have either no parotids, or those organs exist in only a nidimentar}- 
slate; commonly, however, their submaxillary glands ore large. Un- 
der the most favorable circumstances, the digpstion of starchy food tSl 
scarcely ever complete, a considerable portion b ing found in thc excre- 
ment The true function of tlio saliva has been well illustrated by in- 
serting amylaceous food into the stomach of dogs with gastric fistula*, 
aAer tying the salivary ducts, in which case no sugar ran be detected. 

It has been suggested that tlie eventual arrest of the action of sali%*a 
on reaching tlie stomach may l>c duo to tlie digestion of its ptyalino by 
the gastric juice. In artificial experiments, however, such a digestion 
or destruction can not be accomplished, ^_ 

The double digestion, partly salivary and piirtly gastric, occurring w(^ 
the stomach, is doubtless one of the causes of those diflbrcnces wliich 
have been noticed between tiic natural action of that organ and thc arti^H 
ficial imitations of it. The influence of ttie saliva, even under thesoU 
which may seem at first sight to be unfavorable circumstances, is far 
from being trivial, an effect wiiich is well illustrated by the instantane- 
ous manner in which a solution of starcli in water, mixed with an equal 
quantity of saliva and agitated, is transmuted into a solution of sugar. 
In a few moments its viscidity is lost, it fails to give the blue reaction 
with iodine, becomes sweet to thc taste, and readily answers to Trora* 
mer's test. 

Besides tlie duties which have been mentioned, the saliva incidentally 





RELATION OF THE SALIVAKT GLANDS AND KIDNETS. 



47 



DinpUsbes a socondar)' object by its power of rctiuning gases in ita 
. or foam. Atmoapiicric oxygen by ihia qieans la inoor- p^jj^.^ camoi 
ponited with the food ciiiring inuHticution, and is thus enabled air into tho 
lo exert an important influence in promoting the action of 
tho gastric juice. For to the inception of ttiA change which tliat juice 
impresses on the food* oxygen is ncceBsary. It is brought into the cav- 
ity of the stomach entangled or dissolved in the saliva. 

It has just Xiccn mcntiont^d that tltc action of saliva on staxcli is not re- 
ctricteit to tjie production of sugar, but tliaf it may end in the LocUc add 
formation of lactic acid. If, tJierefore, any thing intcn^cnes to ""enl-i^of by- 
check the sujjply of hydrochloric acid» which usually gives drochloric 
aridity to the gastric jiiirc, the syatem possesses Y-ithin itsell'thc means 
of oompeosnting for the ditHculty. In the interior of the digesting mas3 
Uctic ncid is being set free. This acid, as has long been known, can re- 
pUco hydrochloric acid in its pliysiological duty. 

Though so large a quantity of saliva as 20 ounce.s may be secreted in 
»y, tliis being about one lialf of the urinary tlischarge, it is to be ro- 
nbered that the water is not lost to the system^ as in the hitter case. 
When the impure habit of profuse spitting is indulged in, it i>jj_,ii„- f^. 
is interesting to remark the reflected effect which take5 place f«!t or iirofuw 
in the rc-iiiKXHl quantity of tlie urine« and an instinctive desire 
for water, a kind of perpetual thirst. It is probable that, under these dia- 
lling ciremnstonccs, the jx;rccntngo amount of sfdino substances in the 
vii is increased, and tliat, so far as that class of bodies is concerned^ 
the salivary glands act vicariously for the kiihieys, and the mouth ia thus 
partially converted into a urinarv' aqueduct. 

Tlie relation lirtwcen thr .salivary glaii<U and the kidneys is vciy well 
shown after the administration o£ such substances as the RcUtioii Antta 
iodide of potassium. If five grains of this salt he taken in JJ^d^^^ij!" 
pills, and the mouth be then thoroughly washed, in the oouisc i»ji>- 
of a quarter of an hour the saliva will readily strike a blue tint when 
tested with nitric acid ami starch, but the urine ivill not show that reac- 
tion until after a considerable interval, perhaps even an hour or more. It 
irould therefore appear that such a salt must pass again and again through 
the Mli\iUT glanrls before it ia finally disposed of by the kidneys, which 
ofier the ordy outlet for its total removal. 

Among tlie functions of the saliva we ought not to overlook the infla- 
«ioe whicJi its rapid secretion must exert on the state of tension of the 
blood- vessels, nn influeni-e which probably favors the absorjitlon going on 
in the stomach and intestines. 

Tlras prepared by mastication and insalivation, the food dcscCTids into 
tlie stomach, passing along the pharynx, which dilates to receive iL The 
rima glottidis spontaneously closes, and additional security is given to the 



48 



THE DIGESTIVE TRACT. 



Uaa. 



Ff. X 



respiratory passage by the valve-like &butting of tte epiglottic. Thioa^ 
the (esophagus the morsel advances by the (X)ntraction of the muscular 
ooat, with A wave-like or undulating motion onward. The food is now de- 
livurccl at tlic canliac orifice of the stomach, aii<l, entering tliat organ, i« sub- 
initteU to the gastric juice, which is exuding trom the mucous mcmbnnc. 
The digestive tract may be considered as prcscntiug six promuic mt z»- 
niaitrnUoD of P°^*^ — '''^ nioutb, the pharynx, the cesophagos, the Btomadi, 
th« iiigntive the Small iutestiiic the hii^ intestine. Their reUtive posi- 
tion and Bubdivfsions arc illustratetl in Figure 3. — I, the 
tongue ; 2, 2, the phaij-nx ; 3, 3. the 
a'sophagus; 4, the velum pcndulam 
pahiti; 5, 8cctioii of the lan'ux ; ti, the 
|)alate ; 7, the epiglottis ; 8, the lliy- 
roid cartilage ; i^y the metlulla spina- 
lis; 10, 10, bodies of vcrtcbiw; ll^ 
12, spinous processes of ditto; 13, 
cardiac orifice of stomach ; 14, splenic 
e-xtremily; 15, pyloric extremity; 16» 
16, greater cxir\ature; 17, the lew 
curvature; 18, pylorus; 19, superior 
transverse portion of duodenum ; 20, 
middle or perpendicular portion ; 21, 
inferior transverse portion ; 22, gall- 
bladder ; 23, cystic duct ; 24, licpatic 
duct ; 25, ductus communis choledo- 
chus; 26, its aperture in tlic duode- 
num ; 27, duct of the pancreas, empty- 
ing into the duoder:um near to the place 
of entry of the dnctus communis chole- 
dochus ; 28, commencement of jeju- 
num ; 29, 29, 29, jejunmn ; 30, 3(li,30, 
ile\xm ; 31, ileum opening into great 
intestine; 32, ileo-colic valve; 33, il- 
oo-c<rcal vnlve ; 34, oa-cum ; 35, ap- 
pendix vrrmiformis; 36, 3G» the as- 
cending colon ; 37, transverse arch of 
colon : 38, doso(-n<Iing colon ; 39, sig- 
moid flexure; 40, rectum; 41, anus. 
From the interior or mucous ooat of 
the stomach the gastric juice exudes. 
This dutd may be best obtained for ex- 
amination liy gastric fistuhe artificially 
established in animals. As respects the 



n>k« 




THE OASTBIC JUICE. 



49 



of llm Interior of the stomnch, Vh, }?caumont, who liml an opportuni- 

* examining it in the case of Alexis St. Martin, de5cribe.s Aaport of ini*- 

«s of a light pink color, its velvety surface being coated riorofmomacii. 

ttvcr ttilli mucus. On tlie introiluction of food or any irritant, lucid 

oint« protrude from the mucous coat ; these ore the mouths of tlie foUi* 

Hes from which the juice exudes. "When in activity, tlie teniperature 

' the interior of the organ is about lOO"^ Falir. 

The gastric juice is a viscid Huid, with an acid reaction and faint odor, 
filtration through paper it is clear and transparent, and xh^ gastric 

all its physiological qualities. The impurities thus J"'"- 
itcd from it are merely old undigested residues, on which, in no re- 
spect, its qualities depend. It docs not become turbid at 212"^, remains 
loi^ midetwmpoftcd, and retains its digestive power even after it haa bo- 
ome mouldy. It docs not accumulate in the stomach while fasting, but 
[juirpi a stimuhia for its ejection, and even then is produced in a Umit- 
, quantity only. It is secreted by the follicles of tJic raucous membrane 
tlie stomach, which follicles may be described aa cup-slia|»ed ca\'itics, 
3t tlie two hundredth of an inch in diameter, from the bottom of which 
ojoct two or more parallel tubes, tlie mouth of the cup open- nuBe,Trtpdbr 
ng into the stomach, and the tubes ending in a closed term- foUlclw. 
Datiuii in the tissue iK-neath. 'I'owanl the pvlonm tlie cups become deep- 
er, so aa to assume the form of a cylinder, and the projecting tubes are 
hortcr. Between these follicles blood-vessels pass. They are ramifica- 
tionis fn.>m tlie c«i*liac axis, and discharge a double function. As tlie ar- 
, bmiichcj invest the roots of the tubes, tlicy furnish nutrition for the 
JU which are produced in crowds at that part of the arrangement ; but 
rhcn they liavc gained the interior of the mucous membrane, and arc in 
he ridges between the folUcles, liaving assumed the character of veins, 
v. act as absorbents, conducting Ihu inatcri:d wliieh is sufficiently di- 
, into the portal circuhition. Agreeably to this, these Teasels have 
Urger diameter tlian capillaries generally. It seems, thereibre, tliat the 
on of the tube is the production of cells, which, originating from 
I at the bottom and sides of each tube, become perfected as they pass 
tbnmnl* and soon aAer their extension burst or deliquesce, and as the 
malerial they discharge does not possess the acid reaction, it is probably 
I pepsin element of the gastric juice. 



Gmstinaion of the Gaxtrir Jtatt of the Dog 






GutH« JmIm, 
wlthoul mIItl 


OMirk'Jutc*, 

Tllh MllTk. 




973.002 

17.127 

S.CNiO 

4.724 

2.0B7 


U7M71 

17.38C 

2.887 

B.41B 

S.T88 






Cbltiridei uf i<ul,, hmL, rtlc. ointn 




lOOO.OQfl 


1O0O.OO0 



D 




50 



&TOMACU FOLLICLES. 



Tlie preceding tnfale, from Iliibbcnct, sUowa that ncorl}' two tluMa of 
rvoMrtUii of *^® ^**^"^ material of the gastric juice is pepsin. Kjqx>8tire 



lh« gulric 
Juice. 






klucoii < 



to a very low toni(»eratnrc does not dotrrioratc the propertiei 
of tUU aubstaiiL-o, lor it will resume its activity even after be- 
ing frozen. But, on the contrary, a teznperatun approaching ebulUtioo 
destroys its solvent power, and the same effect ensues when it is neutral- 
ized by an alkali. 

The gastric juice acts on iron or zinc with ovolutioo of hydrogen, an 
cflfect Mbich the acid phosphate of lime can not produce. This seems 
to be decisive against the views of those physiologists who hare imputed 
its reaction to the latter gubstauco. 

Tlic digestive power of tliis jnice is impeded by the presence of almost 
any alkaline salt. To this remark common salt offers no exception. It 
is owing to its alkalinity tliat saliva injures the digesting power of gas- 
tric juioc. On the contrary, that |>ower is very much iuercoscd by the 
presence of fal, which promotes the eoQTcrsion 
of protein bodies into peptones. 

The mucous membrane of the stomach pre- 
MMitrt a retictihitcd appcarnnce^ as shown in JF'iff. 
stomnrh foUi- 4. At the bottom ofeachcompart- 

^hTir**;™"!^™ '"t'n^ ^^ *'»« mouths of the gastric 
ttiil Aiactioiu. follicles, the size and depth of wluch 
" increase toward the pylorus. Their exterior is 

partly covered with columnar epithelium, whicli extends over the into 
Fiy-t. vening ridges; the residue is glandular, and continu- 

ally gives origin to granules. The upjtcr part of 
each follicle, as well as the entire surface of the mu- 
cous membrane. Is usually co\ered with mueu.s. 

In J^iff. .0 is a rejire.seiitnlion, given by Todd and 
Bowman, of stonmch folHeJes and tlK<ir tubes in a 
vertical section. The specimen is from tlic dog aflcr 
twelve hours fasting, A represents these structures 
in the middle region of the stomach ; B in the pylor- 
ic region ; a a. orifices of the follicles on the inner 
surface of the stomach ; b 6, different depths at Avhich 
the columnar epitlieJium is exchanged for glandular; 
</, pyloric tubes terminating variously, and lined to 
their extremities wth columnar epithelium. 

J^iff. G, A, horizontal section of a stomach folli- 
cle a little way within its orifice ; a, Kisoment mem- 
brane; bj columnar epithelium. All hut the centre 
of the cavity of the cell ia occupied by a transparent mucus, which seems 
to have oozed from the open extremities of the epithelial ]>articlcs; c, 




T<nWl KM-ilon of ilanuti 



HTDBOID 8TRUCTUBE OF THE STOMACH. 



51 



Fiy-K 



J wellon of fffimvA fr'l . 



^. 



brons matrix surrounding and supporting tlic basement membrane ; rf, 
small blood-vosfwip. 

K, horizontal section of a set of stomach tubes 
proceeding from a single cell. The letters refi?r 
to corresponding parts. The epithelium is glan- 
dular, the nuclei very delicate, and the cavity of 
tlie tubes very smalt, and in some cases not visi- 
ble. (From the dog, by Todd and Bowmaii, nt^er 
twelve hours' fasting.) 

It thus appears that there are at least two dis- 
tinct elaaaes of stomach follicles, differ- v«ricti«of 
ing from e«ch other in anatomical con- siomach 6*1- 
atruction, and, as there is now reason to ' **' 
believe, also in j)hy8io logical function, those which 
arc near the pylonis yielding a secretion which, 
taken by itself, exerts only a tardy action in pro- 
ducing tlie solution of protein bodies, but those 
frr_>m the midrlle and other portions of the organ 
accomplishing that sohition promptly. It is sus- 
pected tliat the acid of the gastric juice is yielded 
by one class of tlieae structures, and the 
pepsin by the other. 

A gt'nenil idea of the stnicture of these 
secreting follicles may perliaps be obtained 
by likening each of them to a bttlc glove, 
tlie hand of wliich oi>ens into the stomach, 
and the tingcrs project ujwo tiic submucous 
tissue beneath. From the sides and tip of 
eadi finger, cells may be snp|Kised to arise 
continually, and, as they are crowded for- 
ward, ihey undergo development, leaving 
the hand in a [lextWt condition, and deli- 
quescing as they pass into the stomach. 

Though we have spoken of tlie-se folli- 
cles aa excavations or cup-lifcc depressiona 
in the mucous tissue, according to the de- 
scription usually givxn of them j^^j^j , ^^_ 
by anatomists, it is to be under- uniciJon of 
stood that this view of their con- *^'*^ 
atruction is pliilosophically incorrect, for 
each, instead of being a mere excavation, is 
truly a distinct organism. analogous in struc- 
Yte br4n. ture and many of its fuactioos to a polype. 



ttu 




i 



52 QUAKTITT OF OAffTlUC JHCE. 

The iiydra, a fiesli-watcr iK)ly])e, may be taken as the tjpe of tlus organ* 
ism. Thid aniaialt J^itj.. 7, couaUts of a bag or digi?sttve sac, a a, end- 
ing in a cylinder, fr» tlie opening to which ia fumishc4l with nuniprous 
tentacloa, c c c; the tentacles enfold in their gra^p objects on which ihc 
hydra feeds, and by their contractions carry ihcm to the sac Into the 
interior of the sac a juiec exudes possessing digestire powers, and soon 
dL^solving food. 

We may thereibre regard the follieukr structure of the stomacli as a 
colony of jwlypcs, tlie tcutados of which are converged into a nnisculor 
tube, constituting tlic ccsophagus. In a stomach of ordinary size tliero 
are proliably a million of tlicso oi^anisms. Digestion is undoubtedly 
conducted on the same physical principles in both cases, though tn the 
polype the food matter enters tlic follicular cavity of which llio body of 
the animal consists, but in man is contained in the stomach, into whicli 
tlie follicles open, and pour forth their digestive fluid. 

With respect to tlic acid com^tituent of the gastric juice, it appears to 
be hytlrochloric or lactic The latter lias probably originated in the man- 
ner ju&t descrilied by the action of the saliva on amylaceous bodies ; the 
former midoubtedly comes from tlic common salt ingested. Perhaps, tm- 
der a delicieuey of common salt, lactic acid dischat^s the entire dut}*. 
(Schmidt regards the digestive principle as a conjugated acid, tlic nega- 
tive constituent being hydrochloric acid, imd pepsin U'ing the adjunct, 
the compound being analogous to Iigno-»nlphuric aeiiL About twenty 
Qaaniiiy of [Mirts of gostric juicc OTB required to digest one part of diy a]- 
ifMtrlcjuice. bumcn, imd about 70 ounces are secreted in a day. If the 
hourly destruction of fibrin in average muscular action is G2 grains, about 
CO ounces of gastric juice would be required each day for muscular repair. 
A vcT)* largo demand is therefore made upon tlie water in the system for 
this use But here the sjimc remark is to be made as in the case of the 
saliva ; the water, aAer accomplishing its object, is not lost to the ccon* 
omy, but is immediately reabsorbed. 

It was remarked, in speaking of the salivary glands, tliat their secre- 
RvneiuiHi p»(i. ''*'" pf^ses repeatedly through them, tlie saliva, as it exudes, 
5a«,'« of extra- being swallowcd, reabsorbed, and so secreted over and over 
[JJJjJj*^ again. In these reix?atcd passages, many salt substances, 
•towMh fUJU- such as the iodide and bromide of potassium, will accompany 
**■ it, the. kidneys, however, eventually rcmo\'ing snch extraneous 

bodies. In like manner, lietcrogcncous matters will make a repeated cir- 
culation through the gastric follicles before a final removal by the kid- 
neys. When the latter organs have been extirpated, the constituents of 
iheir secretion, sucli as urea, may appear in the stomach. 

On the deposit of the food in the stomach, a movement of translation 
is given to it by the alternate contraction and relaxation of tlic fibres of 



SUMMAHY OF STOMACTI BTOESTION. 



53 



tlie maacular coat, aided to a considerable extent by the resp 
movements of the olMlominal walls. The course of this ro- 



iratorjf 



Mi'tiotiB of tho 
lation commonl/ is, that after passing the cardiac orifice the f'j«<i '" tbe 

food moves from right to left romid the great extreniity, and **^ 

then along the large curvalurf! from left to right, returning along the small 

cnrvature, and occupying from one to three miimtea to jwrform this revo- 

lalion, tiie motion continuing for a few mtnntes at a time. 

AVhile tliis is g<iing ftfrward digestion is rapidly taking place, and the 
portions which have sufll-red complete action are oozing through the py- 
loric TaI\-o into the intestine as a semi-fluid and apparently Pannfttion of 
bomogencous material called chyme. Tliis prowss has fairly ^^y^"- 
»ct in in tlic course of an hour, and is usually finished in aljout four. 
In consistency, color, and chemical reaction, tho cliyrae varies with the 
natnre of the food, its chemical constitution, and its quantity ; but under 
common circumstances it presents the acid reaction, for it is to be remem- 
bered that the diurnal supply of liydrochloric acid to the stomach is about 
the tifth of an ounce. Arrived in the intestine, the chyme is pushed fore- 
word by the peristaltic movements, and soon after its appearance in tlie 
duodenum is mixed with several im])ortant fluids — the bile, which xs fiur- 
nished by the liver, the secretion of the pancreas, and the enteric juice 
wliicli is exuding from Bninncr's glands, 

Tlie digestion of the albuminous part of the food commences in the 
stomach, and in that cavity advances far toward completion. Sommary «r 
The action is not merely for tho purpose of bringing those 3-l!j!"i^IJ^';* 
stibstanccs into a state of solution in water, bnt also of modi- tiw tton>arh. 
lying ihem chemically. This change is so well marked that it has been 
found expedient to indicate it by a designation, and hence we speak of 
albumen peptone, fibrin peptone, casein peptone. Tliese peptones arc; 
for the most part, absorlicd by the blood capillaries, though a portion of 
them enters the circulation as a constituent of chyle. In the system, 
whatcrer their origin may have Iwen, they seem to revert to the state of 
Ltood albumen. But, though the production of these peptones is accom- 
plished to the extent that has been mentioned in the stomacli by the gas- 
tric juice, the action is continued and brought to its completion in tho 
sraall intestine by the aid of the intestinal jmce^ It docs not appear that 
the large intestine participates in this duty, since portions of magnlated 
albviinen, or of flesh introduced into it through tistulous openings, are 
voided through the rectum. 

Such 13 the general description of the act of digestion. Wc have nejct 
to enter on a physical examination of what it is that really infti,fn«,or 
taken place in tho stomach. It was formerly supposed that il"* iH-rrea on 
digestion is enlirely due to nervous agency, since, if the pneu- •> * " ■ 
mogastric nerves be divided, the process is very much interfered vnOu 



54 



ARTIFiaAL DIGESTION. 



Bat this interference tates place only in an indirect iraj, for the eectlon 
of those nen-ei! i« atlendcd with auch a paralysis of tlie Etomach that 
Ihoso movements which so wx'll ser^e to mix up the food with the gas- 
tric juice, and expel it tlirougli the pyloric valvt;, are put an end to. 

UidJcr and Scliinidt, from an examination of four dogs with gastric 
Effect at Mxticn ^^^^^^ demonsiratcd timt liie section of the pneuniogastric 
ofihe pnnimo- ncfvcs doTs not cxert that influence on the secretion of llic 
CM cncrvci. gj^g^^-j^^, j^j^g which had been fonnerly Bupj>0Bed, for both in 
quantity and compoeition it remained the same. Even in those cases in 
which both they and others have observed a diminution in its amount, 
the result ought, probably, to be referretl to the shock given to the entire 
system hy the severity of the operation. 

The acidulating rnatcrial of the gastric juice Is hydrochloric acid. Is 
it possible by nrtiftclal mixtures cont^kinlng that substanco to reduce 
food articles to a digested cotiditiou ? This inquiry introduces a deacri{H 
tiuu of the cx}>crimental investigations which have been made iu artificial 
digestion. 

When water acidulatetl with hydrochloric acid is kept in contact witL 
Arttfieiiidu albumcn, no action is perceptible at ordinary temiwratuies in a 
fewioo. moderate period of time. Xl'lLe temperature is raised to about 
150° a slow disaolutiun ensues, which becomes better marked as the heat 
rises toward 212°. 

Hut if to the weak hydrochloric acid thus made to act on albumen, 
pepsin is added, tlie solution takes place willi rapidity at moderate tem- 
jwraturcs. An ounce of water, mixed with twelve drops of hydrochloric 
acid to which one grain of pepsin has been added, will completely dia- 
polvo the wliitc of an egg in two hours at a temperature of 100®, It 
acts in the same manner on cheese or flesh, these nitrogeniKcd articles 
being converted into soluble non-coagulabic bodies. The acid does not 
enter into chemical combination with the dissolving organic matter. It 
may bo recovered from the solution hy re*orting to proper processes. 

^^1len striated nniscular tit>suc is sulimitted to artiticixd digestion, it is 
Artlrlclil dl- ^^^^ divided into its constituent fasciculi, and the transverse 
{;«»ti(>nofmii«- strife then disappear, tlie sarcolcmma being dcstrovcd. The 
course of the action seems to be the same m natural diges- 
tion. In the fo-'cal matter, shreds of muscular fasciculi still bearing their 
striation may be discerned. These, having by chance esca[x>d solution 
during their sojourn in tlic stomach, have passed through the whole 
length of the digestive tube unchnngcd. 

Pepsin — the substance resorted to in these cjcpcrimcnts — may be ob- 
tained by macerating the mucous membrane of the stomach 
ftniiuii'aua for a short time in lukewarm water. This water, along with 
propcrutw of. jj pjjj^ ^j* ^]|g pepsin, removes various impurities ; it may there- 



J 



rnNcnoNS op pepsix. 65 

fore be cast nway ; the maceration being XWn continued with n fresh por- 
tion of cold water, and lht3 being submitted to filtration, and subscf^iucnt- 
ly cvoporatod at a low tcin|)craturc to drj-ncss, yields the pepsin as a 
gummy mass. I'Vom its solutions pepsin may be precipitated by como- 
sive snbliraato ot acetate of lead, and it may bo separated from those 
combinations by snlphurcted hydrogen. AVasmann availed hiniselt" of 
this fact to obtain it in a pure state. 

Cotujftmiiott of Pfjigia. (From ScAmUt.') 

Cnrbon ClO.OO 

Itv(lrop:cn...u CT.OO 

Kitrogea ITIi.OO 

Oxjgvu £25.00 

lOOU.OO 

From this it would appear lliat it contains lcs3 carbon and more nitro- 
gen than the members of the protein group. 

A veak acid therefore possesses at a Jiigli temperature the power of 
brinjnnc into a state of solution tlic various nitroprenizcd food „ . 
matters, and at lower dcgiee^ fails of that property; but in jiiaroaiiigh 
the presence of pepsin tho solvent powers are assumed un- '«"P*"»i'"«- 
dcx tho lattc-r circumstances, and therefore it is said of this subsfanoc 
that it rcpUccs a high temperature. JJy its aid, hydrochloric or lactic 
acids present in the stomach reduce tiio food to a uniform pulpy mass 
— the chyme- Of all acids, these, however, alone arc capable of forming 
digestive iluids. 

I Formerly it was supposed that the act of digestion was simply me- 
chanical, tJic food being ground down to chyme by the mo- j^^^^^ ^^. 
tions of the stomach. Itcaumur^s experiments showed tlic pcrimcntswiUi 
error of this supposition. He took smidl hollow silver balls, •''^"*«'"- 
perlbrated with holes, and, having filled them with meat, caused tliem to 
be swallowed by a dog. When they had remained in the animal's stom- 
ach a Buitablo length of time^ they were withdrawn by a thread which 
had been previously atlached to them. Now if the stomach acted by a 
triturating or grinding |iower, the material within tlie ball would be en- 
tirely prutectcd, but if by a solvent power exerted by the gastric juice, 
the digestion should at most be only delayed. Accordingly, it was found 
that this was what actually took place, digestion being fully, though more 
slowly accomplished, the action commencing on the outside of tiie mate- 
rial, and gradually reaching its centre. If the balls were kept in tho 
stomach long enough, they came out quite empty at last, 

I The idea tiiat tiiere is something more than a simple solution of the 
food effected in tho stomacli, tliat some mysterious eliango is Chk-fuigWtor 
unpnwsetl upon it by tho vitality of that organ, may there- JJJ^^^Jj'iSJl 

{ioro be abandoned. It does not ap{)ear tluit there is any es- tiongfthvfood. 



56 



NLTRITIVE MATTEH 18 DISSOLVED. 



scntial diScrencc between natural digestion and the artificial imitation of 
it, eitlicr as respects the onlcr of action or the tinal result ^lotcoTOTt 
the anatomical consideration tlmt the food is yet oatsidc the body, tlioii^ 
it is iiL^ide t!ie stomach, should be suliicieiit to rcuiuvo all errors of that 
kind. A living surface, such as the skin, never exerts any chemical w> 
lion at a distance; and the luting membrane of the stomach, both as r^ 
golds its pliysiologicjil orifrju and its anatomical n-Iation, is nothing more 
than a reflecte>d continuation of the skin. Tlie act of digestion is com- 
pleted lung before the nutrient material is taken up by the lactoals and 
veins, and tluown into tlie torrent of the eircuhitiou. But then, and not 
till then, is tlic food fairly in the interior of the body. 

1*lie lactcalft and veins can not exert their absorbent action on a Bab- 
stance presented to tliem unless it is dissolved in water. If not abso- 
lutely dissolvetl, at least it must be in tliat condition of minute subtUv-is- 
ion which we see in emulsions. Though it has been slated tliat insolu- 
ble substjmces, such as charcoal, can find their way into the circulation 
in tlic solid state, tlioru docs not appear to 1)e a sufBcient weight of evi- 
dence to 8upjx>rt such an improbabilit}'. In the economy of plants, it is 
Inpluts, all ^ general rule tliat nothing can Imve aooess to tlie interior of 

nntrtDat mate- tli^if eyistcm except it be dissolved in water. All llie %'ari- 
numuMbviu "" it. . i - , * 

nlntiou ill wa- ous gases and salnic substances they require are obtained in 

*"• a state of solution; the former arc introdnccd, for the most 

port, through the Ic^avcs, the latter through the roots. The object ainaed 
at in the construction of tlic digestive apparatus of the animal meclianism 
is absolutely the same. Plants use as their food inoi^nic matter only ; 
the ehii'f materials on which they depend, sucli as the salts of ammonia 
and carbonic add, arc alnudantly soluble in water. The ascending sap 
obtains the former from decaying organic residues in tlic ground ; the at- 
mosphere presents tlie latter unceasingly to the leaves ; and sijice the 
economy of many plants requires eartliy salts, as silicates and phos- 
pliates, which are of sparing solubility in water, the difficulty arising from 
that want of solubility is avoided by the introduction of an immense quan- 
tity of water, whicli, after bruiging into the plant the needful amount of 
minenil material, i« evajwrated oft' at the leaves. Kut the food of animals 
is essentially organic, and this, lieiore il can l>e rtTcived into their blood, 
must he brought into the dissolved state. It must be submitted to a pre- 
paratory oiwration or series of operations. However complicated (hcso 
The oi»raiion» Or the mechanism which accomplishes tiiem may lie, the end 
OB i»i(j fyj-i ans aimed at is clear. The action beeina by tlie cutting, teorin?, 

purvlv dutiiic- , ,. /•111-11 II 11 

•I and m*i lian- »"" crushing movements of the tectli, which break down all 
'"^ the larger jvortious, and carry on the process as tar as it is 

possible by mechanical means. The stomach tlicn continues the subdi- 
vision by eliemical agency, to the end that a condition of solution may bo 



^^^ OBJECTS OP DIQESnOX, 

attained. Digestion is not, therefore to \*itaIiEO tlic food, as tlic ancients 
^ sup|X)»^, nor to communicate to it any new or obscure properties ; it is 
for iLe purpose of comminuting:, suWividing, dissolving, or brining it 
into that minutely suspended state that it can without ditticully submit 
to the absorliing action of the lactcjils and veins. Tliere is n comjilete 
analogy lictwocn tiiis o|K.Tatiuii aud tlic artiticial processes to which the 
chemist rt'soris in his laboratory for the solution of various bodies, llct 
j too, uses mechanical implements — the mortar and jmstJe to grind, the hani- 
fmerto cmsh, the rasp to abrade, MHicn these Iiave carried tlie sulxli- 
Tiflion BufBciciitly far, he resorts to actds or other solvents, and thus 
Im^ok* down tlic compactness of tiie Iiartli-st minerals, and brings them 
into the dissolved state. The animal world presents ns witli ti tiiousand 
illustrations of the principles here set forth, incchaiiieal contrivances curi- 
ously arranged. For instance, birds, who.m' plan of oi^^onization is such 
as to meet the cnse of locomotion tlirough the nir, could not have llie an- 
terior part of tlieir bodies loaded with teeth, nccomjHmied as they must 
bave I»een with a powerful nmsculnr apjwinitiis. Sneh a mechanism 
would have rendered tiie animal tojj-hea\y, and would have been totally 
inconsistent >nlh flying. But, to avoid this dilUculty, that which might 
truly l>c r^^nrdcd as ihc moutli is lodgwl in the interior of the Uidy. nearer 
ilia centre of praWtT,% It is the gizzonl. Instijiet teaches the binl to 
swallow small angular stones, and tlie food, rasped between ]>owcrful mus- 
cular surfaces, is soon brought into a fit condition for tiie action of the 
stomach. The elKimist, loo, puts fragments of glass or of rjuartz into the 
mortar m whicli he is conducting the reduction of a tough or resisting 
sabstance. 

The first object of digestion is, tlicrcfore, the subdivision of the food. 
The 0{icrfttion begins in the mouth by a resort to meclianical implements, 
and when these have carried the process as far as they can, the stomach 
continues the duty. In its cavity, when in full activity, the temperature 
is 10<)° ; n perioiUcally increasing and relaxing motion of revohition is 
kept up, gastric juice exudes in definite qnanlity, the hydrochloric and 
[lactic acids exert their action, and in the course of three or fuur hours 
a complete reduction is accomplished. 

Allusion has been made to the probability that different portions of 
the mucons membrane of the stomach dischat^e functions n!>;non«iiiiTis. 
which are wholly distinct, one portion being devoted to tlic ^^'^u'f^r^H^ 
daboration of pepsin, another to the secretion of hydrochlo- vnt runctioni. 
ric ftcid, another to the preparation of a special mucus. This view do- 
rives considerable fiupjxrt from many facts in com|)arativo phyfiioJogy. 
I In those cases in which the food approaclies, in its mecltanicol and cliem- 
ical condition, to the form which it is destined to assume as a part of the 
(body of the animal receiving it, the stomaeli is simple in construction. 



5S 



DIOESTIOX IX INSECTS AND BIROS. 




Fi^-9- 



and is Httio more than a mere, dilatation of the alimentJuy canal, Uut 

Annio^us at- whcp, SA auioHg tlic hcrbivora and granivora, rtg. & 

SS^Tiia^ ***^" '* * g'^' difference between the form 

milt. of tlic food received and the form of the tis- 

eues to be made, tlic digcali\-e sac no longer presents 

such a simple Btnieture* bnt is parted off into distinct 

rc^ons, or is actually converted into distinct or^ns. 

Tims, in the insect digestive tract shown in J^ff. 8, 
Die«.tiv,....m. ^ ** ^'"^ F^orj-DX, b the ocfloplmgiis, lead- 
tiartnirnu of ing into a crop or inswdivatory poucli, f, and 
Ibmcu. ijjjg jj^jQ i]^^, gizzard,*/, the function of whidi 

is to raftp np and abrade the more resiiiting portions of i 
the food, wliich, when tliis is accomjdished, passes into 
the tnic stomach, e, and from thence info the intestine, ^. 
Tlie delicate vessels about f arc snpposcd to be biliary 
tubes, and A glaiiJuhir sc^rreting organs, 

E., i- • » • ,- ji D«Mii»* tnex oTb ear- 

vcn m tiic^c cases ot luniutc organization, the mu- ihtotoub hwur. 

cons structure remains the same as in larger animals of the same mode 

of life. The photographic representa- 
tion in Juff. 9 displays the same rctio 
ulated appearance in the stomach of 
the carnivorous iHsrtIc as has lx?en de- 
scribed in the cose of that of man; 
and undoubtedly, with similarity of 
structure there is similarity iti the man- 
ner of action. 

A regional division of 

tJic digestive apparuttis 

is also presented !n the 

case of many birds, as 

i>or.«rtit»iH ia shown in the photo- 

lamrte™. graphic representation, 

J'lff. 10, in which we have the digestive tract of tlie eom- 

PifcTrtivecom- ^^^ ^^^^^ ^ ^'"S ^^ oesophagus leading 

l»rtiiufnu oT into tlie insalivating pouch or crop, A, 

^^^'' wliich eni|)ties into the stomach, c\ 

and this into the gizzard, <L In the etomaeh» 

whirli is relatively nmall, the digesting material fi/ 

is mingled with the gastric juice before being 

submitted to tlw action of the gizzard. From 

the gizziurd it is passed into the small intestine 

/,/, In the figure, e is the liver, ff, g^ the cocca, 

and /* the cloaca. i>i«^i«i«wofih.«o««,ibwt 




nt. 10L 



Mucooa mmibraiH- " 

RNMbMllaiU-, 




IIEGTONAL SUBDIVISIONS OP THE STOMACH, 



59 



fnthe ostrich, as shown in Fig. U, tlic local distribution of the glan- 
^'0^ •'■ dulrc very obriously marks out a regional dis- 

tribution of function. C is the cardiac cav- 
ity, tlic mucons membrane of which is stud- 
ded here and there with glands ; G O are the 
o Al \ ^'J^^B\ surfiiccs of the gizziu'd. Among the higher 
quadrupeds, the evidences of a similar divis- 



Fi9.Vt. 



ViO-X^ 



r uf Momaeh of African Mtrld). 



Stomadi ordornnun. BtuuMti ufCipc bynx. 



m of function arc presented. Thus, in the donnousc, Fl/^, 12, there are 
two-compartmunts : a cardiac, C, and a pyloric, I* ; the samo Di™,iivccom- 
being exhibited more perfeitly in the Cape hyrax, Fig, 13. partmcntaof 
In llicse cases the cardiac compartment is often lined irith '""°™'' *■ 
cuticle, but the pyloric not An increase in tlie number of these canities 
occurs as the food Ijecomes mow heterogeneous. In the porcupine, Ftg. 
14, tIkeFB ore four, and in the porpoise, Fig, 15, five. The stomach of 

AeT- U. Fig.\&. Fig. !«. 



]k«aadt of puRMiHiHk Stamack of pofpolaa. Stomach of kUTorogk 

|])0 kangaroo, as shown in Fig. IG, |)ossesses a multitude of these cham- 
bers or compartments, and tlicrefore offers a good illustration of the sub- 
divisions of stomach digestion. 

h^9- 1" TIic case of ruminants 
(\ y^^'^^t^ |K)8scss€S a special inter- 
^^^^^'lA ^/ -^^ est. In titese thens arc 
^^^M/ S^ ^ ^^^^^ what miglit bo termed 
.^ '^^''^^■^^^p'' ,■ _ ,-^ ..: -jid^^B foiu: dirt'crent digestive 

chambers, as ia shoi^*n in 

Fig. 1 7, in which a is the 

ptswtin uTiiiM of • nuaiMtit. oesophagus ; b, tiic inglu- 



DiaESnON IN RUMIXANT8. 

vioa or paancii ; c, the reticulum or honey-comb stomach; eL, the omasum, 
Dif«tJr«conf JJiwiy plies* or third stonuch; tf, abomasum, reed, or fourth 
l>Briimni9of storaaeU; aiidy, the pylorua. The food, roughly triturated 
rummiuits. j^ ^j^^ moutli, enters the ingluvies, in ^vhich it ifl moistened; 
it then paases into the honcy-conib or second Btomnch, which likewise 
rcccircs directly the water tlmt lias Lecn taken, and, after it has been 
tliorouphly moistened Ihexcwith. it is returned to the mouth in small 
portions, to undergo a more complete masticntion nnd insalivation. Bft- 
ing swallowed again, it is now directed into the third stomach, from 
which it ]msscs into tlie fourth. In this it Is submitted to a true mod 
tligp-slion, a gastric juice lieing Becreted from the walls of thb cavity. It 
is the mucous lining of this cavity which j-ields rennet. That thcac com* 
plicated motioiid and theao suct^ssive actions of the diflcrcnt cavities are 
for the purpose of preparation for the true digestion of the fourth stom- 
ach, is clearly proved by the fact that in the calf the milk passes directly 
into t)ie ahoniasum. 

Since fi.-*he3 anrl wfltcr animals generally have no salivary glands, or 
Dl^<wtloo 0"b* rudimentary ones, some physiologists have infoTred that the 
iu (bhcj, ^igu tif the saliva is for the connninj^ling of the food with a due 
jwrtion of water. This would reduce the inijKjrtanee of insalivation veiy 
gnsitly, and, indeed, is scarcely consistent with the ehiborate mcclianism 
wliich has l)oen just dcscril)ed in the case of niminant animals. It is 
wortJiy of remark that, even among tishes, there are some which exliibit 
a true nuniiiation, as, for example, tlio carp. This is not alono for tbe 
purpose of rcsuhniitting the fixxl to the abrading aetion of the phan.'ngcal 
teeth, hut h'kcwisc for commingHng it with the secretion of the pharyn- 
geal cavity. 

In view of the preceding facts, it may be concluded that, so far from 
tliere iH'ing any thing in contradiction to the doctrine that different por- 
tions of the digestive surface of the mucous membrane of the stomach arc 
devoted to Hifferent duties, there is strong e\-iclcnce in support of its tnith, 
derive*! jxirtly trom the instances fumislied by comparative anatomy, and 
partly from the anatomical structure of the gastric mucous membrane. 
The four separate digesting cliambers of the ruminating hcrbivora are 
mcndy an elalmration of the structure which is presentwl by an appar- 
ently homogeneous mucous surface in man. But that this mucous sur- 
face is in reality heterogeneous, and in different regions possesses differ- 
ent powers, is shown by the faet that at one part it presents mucous fol- 
Rcirlonal fune- ^''^™' ** another ppsin follicles, at another follicles for the 
tioiijt tifiiiuiiau secretion of hydrochloric acid. As we approach toward tlie 
•toinar . pylorus, thc cxisteiicc of a now fimction is betrayed by the 

appearance of a new mechanism — thc villi, which have. lxs?;n so wc^ll stud- 
ied by Dr. Neill, and this is even indicated externally in the posterior 



rior ^ 

A 



KEGIONAL DIVT8I0XS OF THE HO£AN STOiUCH. 



61 



• 



^'- ^*- view of llic human stomacli, 7T^. 

18,9bowiiig,accordiiig to Proiess- 
or Ret/.iuB, tluit llw aiitrtuu py- 
lori ot'tlie older anatoiniKts is re- 
ally a sj)ccial compartuiunt of the 
general cavity. The figure ia 
deriv'eJ. from Dumeroua examin- 
ations of the gtomaeh in iKwhea 
of middle -ageJ women, and, us 
represented at c c^ d (I, indicates 
the antnun pylori, a being the 
fcsophagns, b the cardiac orifice. 
Tlic aiitmm pylori ia di&tingaislu 
ed by greater thickness of its mns- 
cular coat, more copious glandu- 
piMienur twtw of tiuman kifliwkeii- Jar dcvelopmeiit, and the presence 

of llip well-known plica? finihriotir, Tlie commencement of thi- duode- 
num al30 forms a Rjx^ial rounded cavity, wliich Professor Ketzitis pn>- 
poscs to name antnun duodeni, characterized internally hy the absejicc 
of valvuLu oonnivontes, and by the dense array of Brunnor's glands be- 
neath its mucous membrane* This part constitutes what has been called 
the fourth stomach in tlic porpoise and some other ectaocons. The so- 
called Ligaments of the pylorus are connected with (he formation of (he 
axitrtini pylori. 

It ha5 lioen remarked that tlie 6rst aim of digestion is the procuring of 
thotood cither in a dis-solved state, or, at all events, in a con- Dijjpj,ii„„ ,(v. 
dition approaching thereto. But, in addition to thi$, pro- •>wnM'iw>*« iw- 
fonnd changea in the very nature of the digested material m«tamori.!io«iB 
must, in an incidental way, be constantly occurring. Thus <"" ^''* '****^ 
the adion of saliva is to produce lactic acid from stoxcli, and thus, m 
ibc stomach itself, starch ia transmuted into sugar. In some cases the 
first Btage of digestion seems to be actually the reverse of what baa been 
here i»et forth. Milk, when received into the stomacii, undergoes coagu- 
lation, and, in like maimer, so also does soluble albumen. But these nm 
only incidental cltanges, the temporary solids thus produced soon lique- 
fying aa proper digestion sets uu There is reason to believe tJiat all the 
protein bodie-s arc passed into the condition of alburninosc, and thin though 
they may h.ive been introduced in the liqnid state. Even soups and 
broilu require to be digested. A solution of gelatine, after (j^,^^ ,^^„, 
it lutt been in the atomach, refuses to gelatinize, a solution i,*t-< ortiiL> r<MHi 
of albumen to coagulate. The circumstance that gases may "j[Ji^.f,'^J^and*^ 
Ix evolved from dig»?sting material, both in the stomach and ■**imiuiiiMio* 
intestine, is a sufiicicnt proof tliat that material is undergoing *^"' 



I lillCBilllC, IS < 



62 



USE OF COMMON SALT. 



a more or less extensive change. But these clumgea are altogether insig- 
nificant whcji compared with those great nictamoi^ihoscs which the nu- 
trient material passes through after it lias been ahsorlrcd from the digeat- 
ive catties ; ami donbtless, at the most, they are only mere gnbdivUions, 
of which the splitting of the sugar or starch atom into lactic ncid maybe 
taken as the ty[)c or mere unions with water, of which the passage of 
cane sugar into milk ttugar is an example. 

The gastric juice, therefore, not only dissolves, but also, in an incipient 
Pnrduftionor ftw^ indirect manner, modifies the food. Protein boilies and 
|tcf>ton«a. gelatinous matters yirlrl sul)stances after its action of the 
same composition as tlieir own, but with different physical ami chemiad 
properties, beuig reaiUly soluble in wuter, imd even in diluted idet'liol. and 
not forming insoluble com|Kmnil.s with mctullinc suits. By Lehmann, 
who Jias ex]uniite<l tliese substancc«, they have been designated as pop- 
tones; and since they may firise without the evolution or absorption of 
any gas, and the quantity of sulphur they contain is the same as that in 
the bodies from which they were derive<i, he infers that the action is real- 
ly on assimilation of water, the other ingredients rciuaining unchanged. 

Turning our attention now to the origin of the gastric juice, it is inters 
csttujr to observe the economicnl manner in wliich its hrdro* 
acvnoit of chloric acid clement is managed. To the proper understanding 
coomoD salt ^j* jj^j^^ jj jg necessar}' to anticipate w!tat will have to bo more 
fully considered in dcscribiug the bUe, a unitbrm inj.Tcdicnt of whidi is 
the oxide of sodium, or soda. Tlic hydrochloric acid of the gastric juioc 
and the soda of the bile arc derived fix>m the same source — ctmimon salt, 
which is either present in the food, or purposely added as a condiment. 
It undeigoes decomposition easily, yielding the two pnxlucts specified, 
tiiat is, hydrochloric acid and soda, and is readily formed by the reunion 
of these substances. 

There exists in the action of the kidneys a speeial jirovision for prevent- 
ing the quantity of chloride of sodium present in the blood from rising 
over 41 parts in 10,000. This, of course, controls iJie amount ditTiised 
through the tissues. The necessity of such a regulation becomes appar- 
ent when wc consider that the rate of the solubility of albumen and ca- 
sein in water is governed by the presence of that substance, as is also tlic 
quickness with which the coagulation of fibrin takes phicc and the re- 
pair of tlie waste of the muscles. 

Common salt introduced into the sj'stcm undergoes decomposition, 
fiimishing hydrochloric acid to the gastric juice, and soda to the bile. 
Considering tlie large quantity of these secretions produced in a short 
space of time, it is clear that tlic drain of common salt must be great — 
not less tlian a third of an ounce a day ; yet the quantities consumed, at 
most, are oidy smalL 



i 




I 



IS this to Lc explained? As^urocUy there is no 
eourec troin which these bodies can come than the one indicated — the 
oomnion salt, and yet it seems to bo totally inadequate. 

T tJiink ihut thin difficulty js mtlier imaginary than real- Tiling are 
so uranged tliat a limited quantity of salt can produco unlimited quanti- 
ties of gastric jtucc and bile ; for the former, associated with the food it 
has digested, scanrcly escapes from tlie pyloric valve before it encounters 
the bile and pancreatic juices discharging into the duodcnmn, and tlirough 
the length of the npper portion of the small intestines these secretions, 
logr-tber with tlie food they have acted upon, are brought into complete 
contact. The reproduction of chloride of fiodium is therefore constantly 
taking j)lace in intestinal digestion, and it returns back to tlic system 
through the absorbents. A^n it undergoes decomposition, its acid re- 
appearing in the gastric juice, and its alkali in the pancreatic juice and 
bile. By thus using a small amount over and over again, great eficcts 
can be produced, and it is then only necessary to restore those small por- 
tions that arc wasted in carrying out the geiieral scheme. 

In the low-pressure marine steam-engine we have an example of the 
anDQ kind. A certain quantity of water is vaporized iu the boiler and 
oondenscd in the engine ; purapc<l back into the boiler to be vaporized, 
and then recondensed in the engine. Comparatively little is required to 
supply the wants of the macliine, and long voyages can be nutde with 

ly as much water as wiU compensate for the necessary waste arising 

the working. 

For the sake of presenting the consideration of the function of digcs- 
witii clearness, it is customary to leave out of consider- *-(^„,pj, j, 
the sulordtnate actions taking place botli in tjie stom- gfnion Ubi»- 
mdi and intestine. This, however, involves a certain amount JSIi'Si^ 
of error, since respiratory or non-nilrogenized digestion oc- tlonbcaJgrif*- 
cora in t!ie fonuer cavity, an<l nutritive or nitrogenixed in the ""*' 
latter. Nevertheless, tiiere can be no doubt that if oor ^icw is restricted 
fo the more imposing cliamctcrs, we arc justified in accepting the dogma 
tiiftt *' stomach digestion is histogcnctic or nitiogeniiied, and intestinal 
digestion is calorifacicut** 

Under the most comprehensive point of view, examining the action of 
the entire digestive tract from the mouth to the rectum, we (^j^^^^ „^_ 
discover a recurrent periodicity. In the mouth, the transi- «i«ry of dig**. 
lory digestion taking place is wholly ex(»nded ujKjn the ca- 
loriiaeient food ; in tlic stomach It is the nutritive portion which is chiefly 
attacked ; in the duodenum there is a return to the calorifacicnt, and in 
the cnccam of animals a resumption of the nutritive. This last is less 
sppanot in man, for in him the coecum exists only in a rudimentary' state, 
rejrraientcd by the appendix vcrmiformis. 





64 



DIGESTION OP QELATIKE. 



As the altpration takes place from calorifacicnt to nutrilive digestion^ 
tlic active fluid changes its chcmicaL relations. In the month and dao- 
dcnuin, alkaline jolcca are resorted to: in the stomach and caHiura, acid 
ones. Wlieiiever there is an accidental inversion of tiiese conditions, the 
result correspondingly ctianges ; so when bile, which is alkaline, regof- 
gitates into the stomacli, tlic digestion of nutritive food is inetantly ar- 
rested. 

In each of these cases the object is tho same: it is to obtain the nutri- 
ent material under such forms that tlic absorbent vessels can readily take 
it wp ; this, as we liavo seen, often involves a metamorphosis of the ele- 
ments of the food where mechanical subdivision would l>ft insufHcient. 
Fibrin has to be brought into a soluble state, and, indeed, albumen itself 
must be modilicd. If it lias been taken uncoagulated or glairy, it be- 
comes opalescent, and passes into the allied form known as albumuiose. 
In this condition it is neither precipitated by heat nor by nitric acid, 
though it is by corrosive sublimate. The cause of this transformation 
probably has reference to tlie relative facility with whicii albiiminosc can 
transude into the venous capillaries compared with albumen. 

TItere is thus reason to suppose tliat tho result of stomach digestion 
is the reduction of the various nitrogcnizcd constituents of the food to 
the condition of nlbuminose. It is plain that fibrin roust come into this 
or some analogi>na condition, for it can not bo absorbed as fibrin, and, ac- 
cordingly, it is found that the blood of the gastric and mesenteric veins 
abounds in albiuninose. 

Intermediate between the classes of calorifaeient and histogonetic fixnl, 
CueoffCflk- Ijclonging, by its composition and conditions of digestion, to 
''■^ tho latter, but by the function it discharges to the former, is 

gelatine, a nitrogenized substance. It appears to be aKvays derived from 
albumen, and any jwrtion which may have been received in tho food is 
never directly assimilated or used for the fabrication of tissue, bnt solely 
ministers to the production of heat. Though thus a calorifacicnt l>ody, 
its place of digestion is tlic stomach. After it lias suflcrcd the action of 
that organ it has lost its power of gelatinizing, cau no longer be precip- 
itated by chlorine, nor give tlie leather precipitate with tannin. The use 
of it under the form of jellies, soups, etc, is always attended with the a[>- 
]x:amncc of an unusual qimnttty of urea in tlio urine, and hence the ad- 
ministration of those domestic preparations, nnder an idea of their great 
nutritive value, is to be looked npon as only a popular error. In an in- 
direct way, however, under tho conditions of restricted diet, usually met 
with in the sick-room, gelatine doubtless maintains an interesting relation 
to the albumcnoid botliea in this, tiiat it protects them from destruction 
by undergoing oxidation itself, and so satisfving tlie requirements of tlie 
respiratory mcdiauism ; for, were there not such a substance present to 



J 




I 



attack, tlie rospired oxyge 
of the proper nitrogcnixed tissues. 

In relation to the ^elatigenons tissues, it may be remarked that gela- 
tine is not an actual constituent of them, but arisefl from them GoUiino not 
by boiling with water. By a like proccsB, sufficiently pro- ""/^'^Jj!' 
loDgeril, a Bimilar subetancc may be obtained from cartilage, «at- 
designated cartilage-gelatine, or cbondrlue. In those cases the mafenal 
onites with water in the same manner tlmt Bturch does in producing glu- 
cose. 

Tlic food must therefore pass through various stages betorc it can be 
jGftted for introduction into tlie circidation, and carried to all parts of the 
'^fttem. It is procured in portions of a suitable size either by the fin- 
gerSf or, in civilized life, by resorting to artiticial implements, the knife 
and fork. The incisor teeth next cut it up, and the molars crush or grind 
it, being worked for this purposct by a powerful system of muscled ; mean- 
time it is incorporated with saliva and atmospheric air. Passing into 
the Btomacli under the condition of a coarse pulpy mass, the gastric juice 
ouriea tl»e process still farther, a more intimate disintegration of its 
(itracturc ensues, and it is eventually brought into a soluble and changed 
forra. The time required to produce this efilHit varies with .y ,-,.■-, 
the nature of the food. Thus it has been noticttd tliat beef vt lUffcnnt w 
U much more quickly acted on than mutton, and mutton '"'"•*'f'«>^ 
aooucr than pork. 

Statements respecting the digestibility of different articles of food 
nrastt howc^-er, be received witb many restrictions. If, as cirenuinaace* 
iito earlier physiologists lielicved, the stomarh was the sole "iteWi^rin^ 
digc&ti\*c cavity, and the intestine only for the pur|K>se of ab- of di^awu" 
■mption, they would doubtless be much nearer to the truth. *7' 
But when we recall that the digestion of fats does not even begin until 
the intestine is readied-, and that the digestion of the nitrogcnizcd sub- 
stances is only in part accomplished by the gastric juice, but goes on 
nndcT tlie influence of tiic intestinal juice throughout the whole length of 
iIms small intestine, we sec at once how imperfect and even incorr&.t are 
the indications afforded by such exjieriments as those of »^paUunzaiu, 
■who introduced 1\hh\ articles into the stom.'U'.h tiiroiigh the ti-sophagus in 
perforated s-ilver vessels, or those of Beaumont, who availed himself of a 
gutric fistula. Neither can wo take, in all instances, the time which an 
article of food will remain in tlic stomach as a measure of its digestibil- 
ity, for this is known to vary with many conditions, as, for instance, the 
quantity introduced at a time, and the condition of the organ itself. Aa 
general illustrations of the digestibility of some of the ordinary elements 
of food, the examples, however, being more or less open to the preceding 
criticisins, the following facts ni.iy be offered. The white of an c^, rep- 

£ 




■ 

i 



66 RELATIVE DIGESTIBILnT OF FOOD. 

resenting Boluble albumen, if introduced into the stomach of a fasting dog 
through a gastric fistula, will disappear in less than an hour ; but if the 
whites of eight eggs be introduced, portions thereof can be recognized 
after four hours, l/ehmann, who made these observations, adds that 
blood fibrin varies in its time for gastric solution according as it is in & 
finely comminuted or a massive state ; in the former instance disappear- 
ing from the stomach of a dog in an hour and a half, but the same weight 
in the latter condition requiring almost twice the time. Coagulated al- 
bumen indicates the commencement of digestion, and even its local com- 
pletion, in from five minutes to a quarter of an hour ; but here again much 
depends on the condition of the stomach and the general state of the 878- 
tem, whether the animal lias been fasting, and whetho- the gastric juice 
is exuding in a dilute or concentrated state. 

So far as such examinations go, thej do not exhibit any marked dif- 
Beapintoiydi- ference between albumen, fibrin, and casein. Gelatine, how- 
guUon, u of ever, is acted on with remarkable rapidity. Beaumont ob- 
gin ia tha served that in an hour 150 grammes of jelly had disappeared. 
■**™***- The experiments which have been made on the digestibility 

of vegetable food introduced through gastric fistuhe are obviously of no 
use, since the chief constituents thereof, such as starch and fat, are not 
even influenced in those circumstances until they have reached the intes- 
tine. Their passage &om the stomach in this unchanged state, or 
changed only so far as their nitrogenized ingredients are concerned, may 
teach us the important fact, wliich should in these inquiries be always 
borne in mind, that disappearance from the stomach is one thing and di- 
gestion another, and that even though a substance may liave passed the 
pyloric valve, its digestion, far irom having been completed, may not as 
yet have commenced. 

The digestion of nutritive or nitrogenized material — ^histogcnetic diges- 
tion — is therefore carried on in the stomach mainly ; and though tirst 
mechanical, and then chemical agencies are resorted to, the object is 
throughout the same — to obtain the food in such a divided and changed 
state that it can pass, dissolved in water, into the capillary vessels. 



INTESTINAL mOESTIOy. 



CHAPTER IV. 



OF CALORIPACIENT OB INlESTDfAL DIGESTION, 



Varwv ^JuttMinaJ DifftttioH.—Strvchitt o/Ou: Jntftitnt.—DvjttHvt FhiUU of tie LatjUvtc— 
Th» t^mtcrttriic Jmte. — Tit Kntrric Jtaer, — Jtmre of IJdierlxlm. — SxnAm t^ Pa/er*a 
(jImmA, IHti. — I>u^eMtion of th: OtrMij/tirnleM awl Jlyirwtirfwnt. — Propertir* and I'lin'*- 
fu» oflJuSii: Acid. — tktrlrmt of the Effee^n ofAcitUiy and AtkaCaU^ oftftr. Dujtatirt Jtdi-tx. 
— /ffiutratiutt t-f Intrxtinal Ifi'frstitmfrom tht wiiXiV/ o/" II7m. — Muhirtg ofBrtad. — IttjhuMV* 
tif Ilmt orvT FrrmmlK. — Comjtarixan of HetMiric and latf^mal ZHifrxtian. — Chaagrs of the In- 
lutiaai VaiutMU. — The I'ueal lieridue*. 

After the chyme formod in the stomach has passed througli the py- 
loric valve into the small inieslinc, the influence of the gastric juice 
continties for a certain time, even after the bile and pancreatic juices 
have been reached. Since their action must be necessarily, in the first 
instance, superficial, the intenor of the luosa is still undergoing fltomach 
digestion. 

But, setting aside this incidental restilt, which at the most can not be 
of long duration, the digestive operation taking place in tlic x«tureofin- 
part of t lie intestinal tract now under consideration is di- tr^timU ditfe*- 
rccted to the heat-making food. "''' 

Tlic organ in which calorifacient digestion takes place may be de- 
scribed as a tube bounded by two valves, the pyloric above structure of 
and the ileo-coccAl below. Its lengtli may be estimated at tiw iniMriiw. 
aboot twenty feet. TIic digestive sui-face, making a due allowance for 
itA increase by reason of its vaK^ular structure presently to be described, 
can not be much under 3500 square inches. The dimensions of the ca- 
lorlfacient digesting surface arc therefore far greater tlian those of llie 
nutritive. 

The interior and acting portion of this tube presents two different 
systems of apparatus, and is occupied in the discharge of two j. 
totally distinct functions, digestion and absorption. It is, rntu-tofinte*- 
fierhaps. this double duty which demands so extensive a sur- '*"*• 
[ lace, and not the necessities of heat-making digestion alone. 

Like the stomach, this tube consists of three coats — a serous, a maa- 
calar, and a mucous. The latter is gathered up in its inte- . .^. 

rior into numberless projecting folds — the valvuln? conniven- nUvubB coiuit- 
tcs. These serve to increase the surface to which the food ^™'*^ 
is exposed, and perhaps afford a mechanical obstacle to its passing too 
quickly forward. They tend also to break the continuous motion, and 
bring the interior parts of the chyme to the surface. The onward move- 



68 INTESTINAL DIGESHTE FLLTDS. 

ment is of course dae to the pressure exerted conjointly hy the straight 
and circuUr fibres of the muscaUur ooat. Anatomists divide the tabe 
into tlireo portions — the duodenum, jejunum, and ileum. 

Fig. a. In J^iff. Id Tvc have a poft- 

'■• tenor view of the duodenum, 

a being its superior or pyloric 
extremity, 6 tlie middle por- 
tion, the jejunum, e? tlie gall- 
bkdder, i the cystic dnct,y3 
|4 hejMitic duct, c tlic ductus coiU' 
^ >^^^H munis, m pancreatic dnct. 
_^^ Soon after the chyme hat 
esca[)ed through the pyloric 
rolve into the duodenum, ii 
PtMicttotTmofibe^wodniim. comes Under the inHacncc of 

llie liile and pancreatic juices, which nro sometimes discharged upon it 
n'nMfW fl *' * common [X)int, and sometimes at a little distance apart, 
itlsofibtin- Almost simultaneously it is submitted to the mechanical ac- 
te«tin«. ^j^jj of the vahiUte conniventes, which make their appearaDCc 

in the vertical portion of the duodenum, and continue in large numbers 
Tintil within the last two or tlirce feet of the end of the tube. Aa the 
intestine is distended, these project with a certain degree of turgidity, 
and accomplish their mechanical object. 

But, besides the pancreatic and biliary fluids, there are other juices 
tlirown upon tlic passing chyme — tlie enteric juice, whidi comes from 
Brunner*8 glands, and a liquid oozing from the follicles of Liebcrkubn. 
]kIoreover, the organisms known as Peyer's glands are affecting the con- 
tents of the tube. Of each of these it is necessary tliercforc to speak. 

1st. The pancreatic juice, secreted by the pancreas, an oi^an bearing a 
PancTvatio resemblance in its anatomical construction to the salivary 
ii"'riS"pTOit gl^Klsi '"id hence usually regarded as one of that gtxnip. 
•rtiee of. The juicc itsclf is analogous to saliva, being viscid, and in its 

reaction alkaline: its specific gravity is about 1.008. ^Vlcohol coagulates 
it* It is said to contain no sulj)hi>cyaniUe nor any auspendod |)articlcs. 
It acts upon starcli even more energetically than saliva, transnmtixig it 
into liugar and lactic acid, and upon fats by forming them iiito an emul- 
siun, so that they are readily absorbed. This lias beeu found to take 
])lace in artificial experlnieuts by submittiug fat substances to the juice 
at a temperature of 100^. 

C^nttitntion ofj^mcrmtic JtiUt c/Z>off. (/Vom ScAmuU.) 

Wuer - „ 900.76 

Org&nic matter „ 90.88 

Inorgooio ** 6.80 

1000.00 



EKTEBIC JCTCE AITD BECnETIO^ OF LTEBEnKUIIN. 



» 



As would be inferred from the difference of eratdsifying power between 
the saliva and this juice, its organic mutter differs from ptyaline. It ia 
estimated that the standard secretion of it is from five to seven ounces 
per diem. 

The action of the pancreatic juice appears to be limited to the upper 
halt" of the intestine, for it is in that region only that butyric acid is de- 
velo{»ed fmm butter. 

2d. Tlie enteric juice ia secreted by the organs kno^vn as Bmnncr^s 

I chmdft, the structure of which hns a certain annlocy to the „ , , . 

■ precoumg, and, like it, tliese doubtless belong to the salivary 

^unup4 Crunner's glands occur chiefly in the upjKT part of the small in- 

^Hbtinc, presenting themselves in the submucous tisHue then'of as little 

bodies, commonly compared by anatomists to hemp-seeds. They consist 

of lobulca with ducts communicating with a common outlet. Their »©- 

aedon possesses a more energetic power when mixed with bile and pon- 

oeatjc juice, than the pancreatic juice alone, in producing fatty emulsions. 

Ill tJie opiiiitin of Bidder and Srhmidt, the intestinal juice, which they 

r describe as. being iuviiriiibly alkaline, not only inetamoqihosc-s starch as 
r^ fia rapidly as the saliva or pancreatic juice, but 

'Ctclflj^viBveav^M /ejns^ nlso exerts as powerful an action on flesh, 
.ffl^A^ca. ^^^^ albumen, and other protein bodies as that 

wliich occurs in the stomach itself. 

In J^ig. 20, which is a half diagram of 

one of these glands, a a represents the mu- 

coufl surface of the intestine, and It the 

I^pr^ lobulated gland, discluu^ing its secretion 

n^cruaorBninwriKUiM.. ihrough a common duct. 

3d. The secretion of the follicles of Liebcrkuhn, which, as shown in 
Fi<j.n, arc straight, narrow cciocal dc- g„^,i^„^f 
pressions of the mucous membrane-, found foi]icie« of 
all over the small intestine^ and in a gen- ^«*'*'*^^''- 
cral manner analogous to the tubular follicles of the 
stomach. Their interior is linefl with oolumnnr 
epithelinm, and in depth they are equal to the thick- 
ness of the mucous membrane, their closed ends be- 
ing therefore in contact with the submucous tissue, 
and their mouths ojKming into the intestine. In a 
Btatc of health they contain a eJcar mucud-liko secre- 
tion. In inflammations of the part they arc filled 
with a more opaque, whitish liquid. Trom their rc- 
iteinbUnee to the follicles of the stomach which secrete {ie|>sln, it may bo 
that they possess a somewhat similar function; but in the 
acbf the icsolting secretion is brought in relation with acids ; in tho 




/Vfi. 




nUvaacC hllldn at Uvbu. 

kmbi. 




70 



TETEBS BODIES AND THE BIZ^ 



intestine, witli alkiiliiie bodiea ; and hence the physiological action may 
differ in the two positions, though the structure and primary fimction 
may be the same. 

4tU, The secretion of Pcyer's glands. Tiiese may he descrihed as cir- 
8««tion tnm ^^^^^ spots, of a wliitiflh color, and ahout the tenlli of an inch 
lVy«f'»giftndj. in diameter, constituting glandular patches fall of cell germs, 
hut without any excretory duct opening into the intestine. It is sup- 
posed that they discharge their contents by rupturing at a certain Btage 
of their development. The solitary and agminate glands appear to he- 






irt 



Vvjmitn glwuU. 



long to (he name jihysiological group. 

TIic two conditions of the Peyerian glands 
arc shown in J^ff. S2, the right one being 
empty, its contetits having been discharged, 
the left one still full. My some it is denied 
that these bodies are connected with intes- 
tinal digestion. The facta that vascular 
loops ]>ass into tlieir graimlar contents, and 
that the lactcals hear a definite relation to 
them, seem to indicate that they are rather portions of the absorbent 
mcclionisra. 

6th. The bile. Of this it is not now necessary to gi\*e a detailed 
, description, since that will occur more appropriately in treat- 
ing of tlic functions of tlic liver. l*'or t!»e present purpose, it 
is suificient to state that bile is a greenish-yellow liquid, of bitter taste 
aud alkaline reaction. It is soluble iu water, changes with rapidity 
under llic intlucncc of the air, or even spontaneously. Its specific grav- 
ity is about 1.028, An ultimate analysis of its organic material shows 
C-g, 11^, O2,, Nj, with sulphur. Its aspect is therefore lliat of a hydro- 
carbon, and it stands in strong contrast with the nitrogenized Iwdies. 
It is a significant fact tliat, even in the lower tribes of life, it is uniformly 
discharged into the upper part of the intestine. Bidder and Schmidt 
estimate the diurnal quantity of bile at 54 ounces, containing 5 per 
cent of solid matter; tliey also give the following table of the diurnal 
amounts of the various digestive tiuids secreted by a man of the stand- 
ard weight, 140 pounds : 

IMunal Amount pfDttffHn Seentiotu. 
Ralira S.30 Ibf., conuimn; solid moUer 1. per ceaU 



nilD S.80 

GuatricJuuse H.OS 

J'ancreaiic Joioe. . . .44 

Intestiiml Juicw ... .44 



5. 

3. 
.t 
1.5 



The bile docs not appear to esert any agency in effecting the digestion 
of either nitrogenized or amylaceous bodies. The period of its max- 



)ax- I 




t 



t 



I 



imiun production, which is 13 or 14 hotirs after a meal, docs not coincide 
with the [)cnod ot'inost energetic digestion. 

With these statements of the nature of the Torioua juicca which pass 
into the email intestine, we may proceed to uivestigatc the phenomena 
of the digestion carried on in that tube. 

In 1832, Dr. Bright, to whom medicine U so inach indel}tc<l for his 
discorcries in relation to the pathology of the kidney, pub- XnnOsUyiiiB 
Itsbed ibrce cases of disease of the pancrens, attended by the poworofpwi- 
appearance of a large quantity of fat in the faces, and drew '^'^' "^J""*- 
tlic int'crenoe that in sucli morbid states the fats arc imperfectly digested. 
More recently, M. Bernard has published experimental evidence to prove 
tliat the digestion of the fats consists in bringing them into the condition 
of an emulsion, and that the pancrcjUic juice accomplishes this object. 

W'liatcver influence the pancreatic and enteric juices can exert on 
starch and oil ontsido of the body, in artificial experiments, they un- 
doubtedly exert it in the small intestine as long as the temperature is 
the sainc. On sturdi, the action, as has already been stated, is to efTcct 
its conversion into sugar, and then into lactic acid. The oils are turned 
into emulsions. The constitutional relation between starch and lactic 
acid is such, that if, in prcRcnoc of water, one atom of the sub-nv(^|on gf 
former be cquaUy and systematically sjdit or divided into iiariMDiolflo- 
two portioiis, those portions arc atoms of lactic acid. And 
since tliis substance contains no nitrogen, its oxidation either artificially 
or in the interior of the system gives origin to carbonic acid and water 
— bodies which can at onco be removed by the action of the skin, or the 
lungs, or the kidneys. 

Jlespecting the digestion of the carbohydrates — cellulose, gum, starch, 
and the diffiTcnt kinds of sugars, it may be rcmarkc<l, that eel- di-5((J(„ of 
Itdoaet of which tho pith of elder is an example, and which theMru-hy- 
occars in a pm-c form in Swedish filtcring-pa|)cr, not only re- """" 
sista, in artificial experiments, the action of the digestive juices, but also 
it would ap(>ear to do so naturally in tho higher tribes, and hence it is 
abun'Iantly found in the excrement of the hcrbivora. To this statement, 
perhaps, ho\Tcvcr, the case of the beaver aifords an exception, DigesUooor 
lh<Te being reason to suppose that this animal possesses the «ii«1m«« 
power of digesting cellulose. 

There can be no doubt, moreover, that many insects have tlie same 
power, for chitin, which may be obtained from their wing-cases, and which 
retains the appearance of the structure of the part, may be considered as 
ocUoIose united with a mtrogenized body, Iiaviug tho constitution of in- 
sect muscular fibre. This substance not only constitutes the skeleton 
of bisects, their scales, hairs, and enters into the construction of their 
trachea.*, but even forma one of tlie coats of their intestinal canaL Since 




72 DIGESnOK or CAIlBOinrDRATES. 

it does not appear that they can metamorphose other carbohydrates Into 
this body, we may infer, as would indeed seem probable, considering tlte 
nature of the food of many of them, that tiiey can digest woody fibre 
Tho digestive apparatus uf man, however, can not exert such a |>ower. 

Noitbcr does it appear that grnn undergoes cither digestion or absorp- 
DigoftUonoT t'on- In arltficial cxj»eriments it also resists tlic action of di- 
E"™- gcstive fluids, and is not changed when present during the 

fermentation of other bodies, even though its exposure thereto be contiit- 
ued for several days. Administered to animnls, it la almost cntiivly 
voided with the excrement. Thus Boussingault, Imving given to a duck 
fifty grammes of gnni-arabic, obtained forty-aix gnunnies from tlie ex- 
crements in nine hours. In an experiment ujton an old rabbil, to wliicli, 
with a diet of eabltage-leaves, ten grammes of gum-arabic were daily given 
by Ijchmann, the gum l«ing administered in solution in water by injec- 
tion into the stomach, no trace whatever of gum could be detected in 
the luine, none in the chyle of the thoracic duct, and none in the blood, 
but it was easily enough recognized in the excrement. From tbis ha 
infers that tho preparations of gmn, which are sucli favorite medicines 
with some physicians, yield to the animal organism only an extremely 
small riuantity of material of a nature to support the resjiiratory process, 
and that their uses, if they are of any use, can bo merely negative in 
acute diseases. 

Of tho carbohydrates, starch is pcrimps tho most important, occurring 
Du^-itiouof ^ >i (1o<^ ^n abnndanec in vegetable food. It can not bo mado 
iunji. ygg Qf jn t|j(, gystera without first being transmute<l into dex- 
trine^ sugar, and eventually lactic acid, these clianges being greatly es- 
[)edilcd if it has been previously prepared by boiling in water, or other 
equivalent operations of cooking. The saliva commences the action* 
whicli in man is even prolonged in the stomach, and in the hcrbivora still 
more decisively in the paunch, in bii-da in the crop. On gaining the stom- 
acli, the fartlier transmutation of the starch is arrested by the gastric 
juice, but after reaching the duodenum it is resumed with greater energy 
than ever, under tho intiuence of the pancreatic juice. Reaching the ile- 
um, the intestinal juice continues the action, though with less vigor. In 
this passage to the large intestine, the starch is gradually assiuning the 
condition of dextrine and sugar, the former substance passing into the 
latter with such facility tiiat it can only be recognized transiently. 
Douijtlcss the sugar tlius arising is in great part directly alworbed, though 
some, Ixforc the coeeum is reached, is transmuted into lacttc acid, and otli- 
cr portions, after j)assing through the ilco-cwcal valve, into butyric acid. 

From what lias been obscn al resjiecting starch, it may be inferred hew 
PiRvsUonof important sugar is, since through the condition of sugar alone 
Bugar. ig starch available for the uses of the system. It is to be re> 



A 



DIGEBTIOX OP 8UGAB. 



78 



oUecfed, however, that sugar itself is only an intermediate or transitory 
stage, throngh which tlie carbobyflrate is passing, a coiisiileratiou which 
explains the circumstance that it does not occur even in the portiU blood 
' to such an extent as might be expected, nor yet in the chjlc. Some 
have been led to ini'er from these facts that tliia substance, like ^nini, ia 
iji reiiUty only very tardily absorhcd, an opinion wliich they sujjpotic to 
bo itTBngthcncd by the circumstance that glucose or any other kind of 
sngar, iniroduced into the jugular vein, runs through the course of the 
circnlation, and is secreted unchanged by the kidneys. Hut it is to be 
remembered tliat portal blood is very different from the proper systemic 
blood, ajid tliat tlnipe are many changes, beyond all question, which can 
take place with nipidity in the former, but wliich do not take place in the 
Utter. 

&igar, whether it has been received as an ingrwlient of tlic foo<l, or 
arisen from the metamorphosis of starch, is, as we liavc said, only a tem- 
porary form, which passes quickly onward to the state of lactic acid. To 
this we must intputo the acid reaction which is observe<l throughout the 
length of the small intestine, and which can not be attributed to the gas- 
tric juico, a reaction ocntrring in spite of the alkalinity of the bile and. 
pancreatic secretion. This pushing of the carbohydrate forward to the 
st«lo of lactic acid is very generally imputed to the intestinal juice, which 
greatly re-enforces the power of the saliva and pancreatic Buid; some have 
even supposed that the bile aids in producing this etfect. Of this, how- 
ever, there is no satisfactorj- proof. 

From the experiments of Von Becker, who injected saccliarine solu- 
i tkms at intervals of a quarter of an hour into the stomach of rabbits, it 
I lima fonnd that 4.5 parts of sugar were absorbed each hour for every lOOO 
|]MUl» weight of the animal. Wluitevcr may have been the form of sugar 
admin is tcrctl, as, for instance^ cane-sugar, it quickly passes into tlic con- 
dition of glucose in the intestine, and from that to lactic acid. Thus sug- 
ar of milk may be traced in an hour as for as the cax;um, communica- 
ting to tlie contents of the small intestine an intense acid reaction. 

Since lactic acid dischari^s very important oflices in the animal econ- 
ooiy» it may be worth while to observe its properties, and pro«iurtionand 
Ibe dreams tancea under which it is produced. Very many proi»cnie»of 
liquid* containing organic matter yield it abundantly: thus it *"'*<'■"*'• 
ia found iu sauer kraut., a preparation of cabljagc. It is, however, more 
cooTenicntly obtained from milk, and hence the term lactic aciiL The 
dilotnl solution obtained from this source, being concentrated by evap- 
oration, furnishes a sirupy liquid, heaWcr than water, ha^nng an intenso> 
[ \y sour taste, a great aiBnity for water, and therefore attracting it from 
I tbo air, and dissoU-ing freely in it. With metallic oxides it forms soln- 
1 ble salts, and in the concentrated sirupy state has the remarkable con- 



74 



LACnO ACID. 



sUtntioa that it contains six atoms of eacli of its elements, carbon* bjr- 
drogen, and oxygen. 

The production of this acid in organic substances is very common. 
It dejxrnds on the same principle 03 presented in duodenal digestioot 
which it therefore very strikingly illustrates. As an example descr\'ing 
of attentive consideration, its development in milk nuiy be otfcrcJ. 

Wlien milk is exposed to tlio air it eventually turns sour, the sour- 
ness Unng due to the ap{>earunce of Inotic acid. In its sweet state, tlie 
milk may lie regarded as consisting of casein, or the cnrrly principle, t 
substance Iclonging to the protein group, insoluble in pure water, bat 
abundantly soluble if a little free or carbonated alkali be present ; of milk 
sugiu-, dissolved, and of butter held in suspension in water. The ao- 
p^-^j . tion taking place during the souring is aa follows: Under 
Wtic iiH.i tbo influence of atmospheric oxygen, which for this purjwsc 
"^ "" ■ must have access, the nitrogcnizcd principle, the casein, be- 
gins to change, and, for reasons presently to be more jtarticularly cxum- 
incd, impresses a change on the sugar, s])Iitting its atom so as to gi\'e 
rise to the production of lactic acid. As this forms, it renders the cos^ 
insoluble, and the milk begins to coagulate, to prevent which a little car^ 
bonntc of soda may from time to time be added. All the sugar origin- 
ally present in the milk is soon acidified, bat a much strongci solution 
can bo made by adding more milk sugar as the process of exbaiistion. 
goes on, and the change can be thus kept up until the casein itself is 
quite consumed. 

On examining this process critically, we observe that every thing de- 
pends on the change occurring in the nitrogeuized principle, the caseiiu 
lliis, under the circumstances, takes on an incipient oxidation, and com- 
pels the sugar atom so to di\ndc as to give rise to the production of lac- 
tic acid. This ceases the moment the casein ceases to change, and re- 
commences the moment the casein is pcnnittcd to reoxidize. The de- 
struction taking place in the casein is prnp,igatcd to the imgar, the 
physical peculiarity being that the atom of sugar is merely divided, fi»- 
Burcd, or split, and gives rise to the production of lactic acid, and no 
other substance. The whole process is therefore essentially one of sub- 
division, a conclusion wliich should be carefully borne in mind in apply- 
ing these experimental principles to the physiological function of diges- 
tion. So far as the result is concerned, the two cases are the same. 

Mary other organic liquids furnish similar illustrations. Thus, in 
Pmdnctioncf ^^^ operation of making starch for commercial purposes, cou- 
inctir i.^d siderable quantities of that substance are turned into lactic 
rom&u ^^jj^ constituting what the manufacturers term wur li^tt&K 
Nor is it even requisite tliat so much water should be present as to give 
the liquid condition ; for if wheat flour be made into a paste, and kept for 



lACTtC ACID TN THE STETirM. 



Ifiomc days in a warm place, its gluten induces such a cluingc tliat tho 

' starch turns into lactic acid, and the paste becomes sour. 

Of lactic acid there are two kinds ; that derived, as hereafter stated, 
from muscle juioe, is the alpha lactic acid, and that from the Alpha ud burs 
feniiciilation of sugar the beta lactic acid. As it occurs in l«^o»cnl. 
tlic gastric juice, associated with or replacing Jiydrochloric acid, it is of 

I the beta rariety. Whatever may have been the source of this portion 
of it, whether it haa been derived by gastric secretion or llirough the 
transmutation of amylnceous food by the saliva, its abundant occurrence 
in the contents of both the sninll and large intestinal, in which it is rcc- 
<^izod by the peculiarities of ita zinc and magnesia salts, confirm iho 
coQclusion that in this case, at least, the beta fonn arises from the opera- 
tion of the digestive juices. 

Xjactic acid undergoes rapid absorption through the intestine, and is 
as mpidly di.^]io»ed of in the system. Thus Lehmann found, nfter tak- 
ing Iialf an ounce of <lry lactate of soda, that in thirteen minutes his 
nriue liad become alkaline. On injecting the same salt into the jngnlnr 
Tcin, it appeared in from five to twelve minutes as carbonate of soda in 
the orine. 

Bereclius first discovered the existence of lactic acid In the juice of the 

Licbig showed that, in quantity, there is more p^i„^,|rtn of 

r in this source than is sufficient to neutralize the alkuli l»c''<: •^i'l t'y 

^of ail the other liquids or juices of the lK>dy. Muselc lac- ^ " ""^ *** 
tic add is removed away with rapidity by the lymphatics, Berzclios 
conctaded tliat its quantity increases In proportion to the exercise tho 
imisele has undergone ; and this would lead to the inference that it is 
one of the chief products of muscular waste ; for it is not to be supposed 
that its appearance in muscle juice is because those organs attract it 
irom the blood, in which it pre-exists, derived, iierliaps, from the trans- 
formation of amylaceous substances in the inteatinCi for the muscles of tho 
camivora yield as much of it as those of the hcrhivorn ; and though it can 
oot be artificially made directly from albuminous material, yet it would 
•oem that, with urea and ammonia, it mtglit arise from the breaking up 
of caratine. From glycerine lactic acid may be also developed, Wlien- 
erer ati excess of it is produced lu the system, either by muscular action, 
tmxisiuil diet, or imi)erfcct oxidation in the blood, it may l)c detected in 
the oriue. Under ordinary circumstances, doubtless, very large quanti- 
ties of it ore destroyed in the circulation, giving rise to the production of 
carbonic acid and water wth a disengagement of heat. 

We can not hero fail to remark how the process of comminuting the 
food is carried for^'ard to such an extent that the absorbent Tfacwdignt- 
Tcssels arc able to take it up. The action first begins, a3 has i*,^ JJJJJS^^ 
ahown in detail, by cutting and cnishing implements, i«o«. 



76 



DIGESTION OF FAT. 




the tcetb, and when these h&re carried the eabdivision as far as mechanical 
incana can, it is continued by chemical ogenta. Upon these principlES, 
the pancreatic juice di\'ides starch into Uctic acid in duodenal digestioo — 
a product which, without difficulty, Hnds its way at once into the s/stenh 

Besides starch and sugar, there is another group of bodies lidoagiBg 
DismUooof to the class of calorilacient food, wliich, in the case of camiv- 
^^ orous animals, weins to Ix; exclosively employed. The fals 

and oils constitute this group. 

The action of the pancreatic and enteric juices upon these bodies, in 
bringini; them into the condition of an emulsion, has already been stated. 
That tlii^ occurs iu the intestine appears from the fact that if the pan- 
creatic duct be tiedf no cinnlnion forms, and the chyle in the lactcali 
is limpid instead of being milky. In the rabbit tliis duct opens much 
lower iu the intestine than the biliary, and it is observed that it is only 
after the food has passed that pjint that it becomes emulsioned. The 
place for pancreatic digestion seems to be very constant in tribes that an 
far apart in habits of life. Thus, in fishes, the pancreas oonf^ists of a 
onet of ccecal tubes, smroundiing the pyloric e^ttremity of the in 
each o|>cning into that organ by a separate mouth. 

The lats reach tlic dnodennra witlioiit tmdorgoing any change. There, 
under the influence of the pancreatic juice, they bceomo Rubdi\*ided into 
extremely minute portions, whicli, absorbed by the lactcals, give to the 
chyle its cliaractcristic aspect. Beyond tliis condition of subdivision 
no other change is thus far impressed, the fat of tliv lactcals being abso- 
lutely t!ie same as that of tlic chyme. To the introduction of fat into 
the lactoaU, the presence of bile seems to be necessar)*, or, it* not abaolnle- 
ly necessary, absorption is greatly facilitated by it 

Thfi gastric and pancreatic juices stand in a remarkable relation to one 
Bernard's doc ""o*''<'''« *''6 former being an acid liquid, having tlie jxiwer 
trine of the ef. of bringing into a state of solution nitrogrnized bodies, such 
and aikaHiiUy ^^ fibrin ; the latter alkaline, without action on nitn.igenized 
in 111* ditceftt- Iwdics, but operating energetically on starch, sugar, and oils. 
From this it miglit be supposed that the intrinsic qualities of 
these juices are different, and that they act in this manner bccansc of a 
special dissimilarity of eonstitntion. 

Attempts have been made to prove tliat this difterenoe of action d^ 
pends wholly on the chemical relations of the jtiice itself. If pancreatic 
juice or saliva be purposely acidulated with livdrochloric acid, it is said 
that it loses at once the power of acting on calorifacicnt food, but can 
bring about the solution of the hi.stogcnctic. On the other hand, if gas- 
tric juice be rendered alkaline by admixture with soda, it no longer dis- 
solves fibrin or coagul.'itod albumen, but gains the power of acting on 
etarch and sugar. Since, then, it thus appears that the same or^janic body 



OBOAKTC PBlXCmE OF DIOESTrVE JUICES. 



77^ 



becomes endowed with one or otlicr of these proprrties, according aa it is 
acidulated or aikalinized, the Ainction of digestion is presented to us un- 
der a simple aa|>cct. It is upon the:^ principles that we may expUiin 
the fact that the presence of bile in the stomach suspends or arrests the 
digestion going on in that oi^an. 

Though the views here expressed ore such as arc received among many 
chemists, yet it is still open for consideration whether the tii« Mum or 
nature of the result which ia reached in these cases docs not, *'"' «ft'«"»': »a- 
to a great extent, depend upon the nature ot the organic biipuruutifaui 
changing body, Ihe ferment, M'hich tirst seta up the action. ^° rwiaiwi. 
Uany circumstances would lead us to infer that this must be the case, 
and tlutt. as with ditfcrcuccs of temperature, so also with these ditl'crcnces, 
the final result may present distinct variations, though they may be with- 
in a certain range or limit. Thus, though the saliva and pancreatic juice 
are both alkaline, and both impress in a general way the same digestive 
change on starch and sugar, a minute examination of the results of their 
action would doubtlesa leit J to the detection of sLadcs of diflerence — va- 
riations which could oidy bt- allribulcd to the diflerHnco betwewi tlic oct- 
hre Clonic principle of the j>ancrcatic juice, and ptyaline, the correspond- 
ing principle of the saliva. 

The imputed control which the alkalinity or acidity of the digesting 
juices ejcerts in determining t]ie result, illustrates tlie import- Kpi^domof 
aut function discharged by common salt, which fumislies to cnmmon mU Ln 
the juices of Uie stomach and intestine tiie characteristic in- ^" **"' 
grdients they require by breaking up readily into hydrochloric acid and 
aoda, and re-forming at once whenever tlicse materials arc bronght in 
contiKt, There is, therefore, an important reason for the instinct which 
animals display in resorting to the use of thia substance, as in the buffa- 
lo licka at the West, and the necessity which men cxj»cricncc to add it 
as a condiment to tiieir food. But though, by furnishing an acid or al- 
kali, as the case may be, it detennines tbo nature of the work wliich the 
secreting juices pertbrm,* it is not to be regarded as the prime mover of 
the change. It guides rather tlian works. The efficient principle bring- 
ing about digestion appears always to be a nitrogcnizcd body, acidulated, 
perhaps, for the production of one duty, and rendered alkaline for the per- 
CormaDoe uf another. 

Directing our attention now more partiadnrly to the phenomena dia- 
playcd by such a changing nitrogenized principle, the following illustra- 
tions will serve to show that there ia nothing mysterious in its operation. 
Out of many cases which might Iw aelccte*!, tlioae now to bo offered are 
mon particularly interesting, since they refer to substances extcusivcly 
Bflod in the diet of man. 

it, o( wine. A grape, if perfectly sound, will keep for a consider- 



nXCSTUATIONB FUOX WDHS KSD BBEAD. 



IHurtrition ^^^^ length of time withoat undergoing any change ; hut if 
from ihfl nuk- a puiictuie he made in it to give the air access, it rapidly Je- 
^ * ***■ leriorates. The precise change taking place i* perhaps bet- 
ter understood by ohscrvBtions on the ejcpresscd juice ot' this fhiit. If 
grape* be pressed beneath the puriacc of quicksilver, and the juice be col- 
lected in an inverted jar, witliout ever coming in contact with the atmos- 
pheric air, it may be kept for a long time without any apparent change; 
but if a ftniall quantity of air, or only » single bubble of oxygen is p»- 
mitted to enter the jar, and the tcjuiiexature iii that of a »uinmer*s thty, m 
intestine commotion or fermentation at once cnsiiPi*, carltonic acid escapes, 
alcohol arises in the liquid, and the sugar which was in tlie grape-juice 
disappears. But (lie quantity of sngar thus cajmble of being destroyed 
is limited, and a point is eventually reached at which no more sugar can 
be decomposed, and no more carbonic acid set ^c. 

The juice of the grape contains a nitrogenized principle resembling al- 
bumen- Tt iH this whicli is in reality the active body. So long as ox- 
ygen is excluded, this nitrogenized sulifltance remains unaltered, but the 
moment the air finds access a change begins. The sugar which is pres- 
ent in the juice becomes involved in the movement going on, which ig 
propagated by degrees to all its atoms, divitUng each into two well-known 
and well-marked bodies. The jwriod at which no farther change takes 
]ilrice in portions of sugar which may have l>ecn purposely added is 
wlien the nitrogenized principle has disappeared. 

Carbonic acid and alcohol arc the two substances arising in this de* 
composition. Their mode of origin is obvious when it la understood 
lliat one atom of Hugar can be so divided aa to yield four of carbonic acid 
and two of alcohol. In this artificial instance, the subdivision is even 
more complex than tliat which occurs in duodenal digestion, in whicli the 
sugar atom is uuhdividcd into two etpiol and symmetrical parts, two 
atoms of lactic acid. In the following formulas, (1) represents the case 
of vinous production, (2) that of duodenal digestion : 



(1) 

(2) 



C.,H„0,=4(CO,)+5(C,H.OJ. 

c„ir„o„=2(c,H,oj. 



I 



Second, of bread. If, in the preceding case, a transmuting nitrogen- 
ized bodv breaks tiic sucar atom so tliat alcohol is one of the 

ninslmtion ■ , • • - , n • , • - . 

rn>iii maklDg prouucts, snu upon this principle all wines and intoxicating 
ortirrnil. liquors are made, the instance now presented is of far more 
interest to the well-being of man. The use of wine undoubtedly adds 
not only to social enjoyment, but sometimes conduces to health — a ben- 
efit, alas ! often attended with a thousand ills. Not so with bread, em- 
phatically and truly descrilx-xl as the staff of life. 

The making of wuie and of leavened broad are two of the oldest cliem- 



J 



nxrsTftATioy from the maeino of bread. 



79 



pfocessos. Their ongin i^ lost In a remote antiquity, and so uni- 
lersaltj are their benefits acknowledged that their use is dttiusod all over 
le world. 

Kxpcricnce proves that the Iwst bread is made from tine whcaten tlour, 
Dixed into a paste with a due proportion of water, A certain quantity 
if a nitrogenizcd Bubstancc undergoing incipient oxidation, loniiod ycatit, 
added, and llio whole submitted to a gentle tcni]>erature. AU flour 
Kmtains a small quantity of sugar; on tliis the yeast immediately acts, 
ividing it, as in the former case, into carlK>nic acid and alcohol. If 
noQgU su^ur is not present, more under tho circumstanccB is formed from 
iorctu The acid gas, as it is set free, can not extricate itself from the 
uiTOunding dough, but expands into a thousand little vesicles or bub- 
llc», which give that peculiar jxirosity for which this kind of bread is so 
ghly pri?^. At this period, iK-forc leaking, the other Bubatancc which 
IS aii»en from the destruction of the sugar — the alcohol — is contained 
I tho dough, and is expelled tlicrcfrom along with the excess of water 
y the high temperature of the oven, which also, by increasing the expan- 
Bon of tho included gas, adds to the porosity of the bread. In some 
MkiDg establishments arrangements liavo occasionally been made to con- 
ac the alcohol as it rises from the bread. Tho good and evil of lite 
oAon closely intcnnixcd. Tho advocate of total abstinence from al- 
ohol may with reason look upon half-baked bread distrustfidly. Tho 
ncmy is lying in ambush for him. 
On some occasions, instead of using yeast, a piece of leaven, that is, 
n^ in a state of incipient putrefaction, is employed. The mode of 
icCioa is, however, tl»e same. The use of this material well Ulustrales 
he progressive nature of those cliangcs, and how the action gradually 
Bsea ^m |ioint to point of the entire mass. It is written, "A little 
kvcn Icavenelh the whole lump." 

In the cases here presented the action is one of subdivision. A Com- 
dex atom has its constitution broken up, and is se|»irated TheMutiofM, 
to distiuct parts. When such a change is once commenced ^^*ji^f^l*^ 
; a mass, there is a liability for the whole to become in- BubdivUiuM. 
)Ivcd, just as, when we ignite one point in a pile of combustibles, tlie 
re spreads tlironghout ; or as, when on one part of a piece of fresh meat 
smaU |iortion in a putrescent state is laid, the comq>lion, with measured 
ity, proceeds from part to part, until the whole is decayed, On« 
another, the particles submit in succession. 
T all these subdividing actions heat exerts the most extraordinary 
finenoc, so that for a given cSi-ict to 1w produced it is abso- Inniunccof 
tely necessary that a given temperature should bo main- J^J^JSJ^ 
incdL Tliiis, if wo take the saccharine juice of fdniost any •cUon». 
of £ruit, and cause it to be acted on by a changing nitrogcnized body, 



80 



EFFECTS OF TEUFEBATL'RE OX FEKUENTB. 



it wiH yield, as just stated, alcohol and carbonic acid bo long as the teiii- 
perature ranges about 75'' ; but, every thing remaining llua same, if 
ihe temperature be raised to lOlP or 120^, neither alcohol nor carbonic 
acid 19 fomif'd, but in their stead other products arise, such am lactic add, 
gum. and nmnna. Tliough, therefore, diTomiKtHitiim will go on throngb- 
out all tiiis mngc of lempomtarc. the prmlucts will raiy very much, al- 
cohol lieing formed at a low, and lactic acid at a liigh degree. 

Again, the decomposition of milk furnishes a very instructive instance 
When the temperature ranges from 50'^ to 76®, the liquid tuma sour, 
owing to the formation of lactic acid ; but if the Icmjionituro ia over 90°, 
the products arc different, for now a true vinous iV'rmcntntion seta in, al- 
coiiol and carbonic acid appearing. It is on this principle that the Tir- 
tar.4 make an intoxicating liquid from marc's milk. The fcnnentjition of 
milk, therefore, yields lactic acid at a low, and alcohol at a high degree. 

On comparing these illustrutions, the results stand in direct contrut, 
but both show the great influence wbieli a s])ecific degree of heat exer- 
cises over such snlxliH^ions ; and, as a conswpicncc of this principle, 
whicli obtains equally in the physiological case, we lecognize the nece»- 
sity of maintaining the cilvity of the stomach and intestine iiniformly 
at u temperature which is fixed, otherwise there would cease to be any 
unilbrmity in the subdivision of the food, occasioned by the digestion 
there going on. These principles, moreover, lead to the explanation of 
the action of such stimulating subt^tancci? as alcoholic liquids, |>cppcr, 
etc., which at once determine a local elevation of temiierature ; they also 
explain the injurious etfcets which may ensue from intemperate dnraghts 
of ice-cold water. 

A nitrogenized sul>stance, in a state of change, can thus bring about a 
definite action on fibrin, coagulnte^l albumen, or casein in the stomach, 
or on starch in the intestine, so long as a temperature of 1<X)° is main- 
Lou of (lowcr tained, but in every known instance this transmuting |>ower 
Ii''ifiKh"uliK«^ ** totally destroyed by exposure to n very low or ^-ery high 
•tur«. degree of hejjt. Large masses of animal matter— whole ca> 

casses — may be presened for many centiuries imchanged if the tempera- 
ture is kept down to SS*^, A striking example of this occurs in the case 
of the extinct elephants which arc occasionally thrown on the shores of 
the Polar Sea from icebergs in which they have been entombed for 
many thousand years, their llesh remaining in a perfectly fresh and nn- 
det'aywl state. And as respects a liigh temperature, an exposure to 212° 
totally destroys the jwwox. ( )n tliis princijile, all kinds of meat or veg- 
etable substances may be indeHniteJy preserved. If such are inclosed in 
metallic canisters, so as totally to exclude the atmospheric air, and ex- 
pusfd to a batli of boiling water, they may then be carried around the 
world without nndcj^ing any cliange. 



J 



AETIPICTAI. PR0DUCT10:T OP TAT. 



81 



One of these illustrative cases still remains. It belongs to tho class 
of clunges now under conaideratioii, and desen'cs a prominent cxnniinn- 
tion from its comicctiou -nitU Uuodcual digestion. It is the production 
of ia.tty liodiea (torn starch and sugar. 

Phyaiological considerations a.ssure ua tliat there are circumstances 
tinder wiiicli oils and Jats cau be tbnncd from starch and p^„ci[(^ of 
sugar in tho system. AnimaU can be fattened by feeding fots rr»m au- 
on potatoes, or otlier such food, Ui which the quantity of oil >""'«*• 
ia quite inaigniticant.- Bocs can make wax, which strictly belongs to the 
group of fats, though they are fed on pure while sugar. 

Such results cuu l)o artificially imitated. If a strong solution of sugar 
be mixctl with a Hinall quantity of casein and {K>wdered chalk, and ex- 
posed to a tenipcrature of more tluui 80^» carhouic acid and hyilrogen are 
eroK*eil, and but^Tie iu:id forms as llie hutyratc of lime. This acid sub- 
stance ia a colorless oily Liquid, Iiaviiig the odor of nuicid butler, iu 
which indeed it exists. 

From a review of all the preceding facts, we may conclude that a nitro- 
genized Etubstance secreted by the follicles of the stomach, Contnutof 
iLod imdergoing incipient oxidation, aciduhited with hydro- SJi^ d"i«fr' 
chloric acid obtained by the decomiK)sition of common salt, ii«u. , 
or with luetic acid produced by a continuation of salivary digestion, has 
the power of dissolving coagulated albumen, and generally those articles 
of food which belong to the nitrogenized class; that tliis goes on in 
the stomacli, it being the functiou of that organ to cfiect the digestion of 
thU luud of food, and thereby contnbuto to tlic general nutrition of the 
wrsicm. The muscular tissues arc supplied from this source, and by the 
stomach their waste is repaired. 

Another and distinct digestion takes place in the intestine, commenc- 
ii^ immediately after the food gains the duodenum. It too is brought 
about by tho action of a special liquid, a mixture of the pancreatic and 
iatotinal juices. Tlie clieinicil reaction of this juice is alkaline ; in this 
roipcct it is therefore antigonistie to the gastric juice. This quality is 
due to llie soda it contains, a substance derived co-ordinately with hy- 
drocJdoric .icid from the dc<;omiK)3ition of common SJiIt. The digestion 
of starchy and saccharine bodies is thus ejected by dividing thcin so as 
lo produce lactic acid. 

Tbia done, common salt is reproduced by the commingling of the gas- 
tric biliary, and [lancrcatic products together. The salt is carried by the 
\Ui into the interior of the system, to be again decomposed. 
aver, the {Kuicreatie and enteric juices reduce the oleaginous and 
iktty bodies to the condition of an emnlsion, or, if they be not present 
in the food, give origin to them in the way just described. 

The reaction of the intestinal contents not only differs iu different por- 

F 




82 8.VLTS AXD GA8ES OF THE IXTESTINE. 

SacwMlra tions of thc tubc, Imt in the same region, in diffecent puts 
truui^thmlch **^ ^^^ mass, its cxterior may be alkaline, its interior add, or 
die ititeMjuc. tbe converse, Thc acidity which has been imparted by Uiu 
gastric juice seems generally to have disapj)eared some time before the 
Urge intestine is reached. In this an alkaline reaction is observed. Tlw 
GSUSes of tliis prolonged acidity arc very various. In part it depends on 
the nature of the fiwd, in part upon thc gastric juice, as has just been 
stated, and in part U{)ou thc production of lactic, but,\Tic, and other adds. 
Thc resinouH ingredients of thc bile may be detected a^ tar as thc lower 
extremity of thc ileum. Glucoec, originating in the action of thc jmuicto- 
atic and intestinal juices on starch, umy be rvcognixed throughout thc 
wliolc length of tlie canal, but tliat which has been introduced in the 
foo<l seems to be absorl)cd in thc stomach itself; thus, in milk-fed ani- 
malf), sugar docs not appear to descend beyond the jejunum. Thc trans- 
mutation and reabsorption of biliary matter commences in thc snudl in- 
testine and proceeds eontinuoiL<(ly, so titat by the time thc middle of that 
portion of thc tube is reached, half the bile is gone. 

Since thc intestinal absorbents c^n o)dy take uj) a definite proiX)rtion 
of fat, it might be ejcjiected, as is really tlie case, that al'tcr an unusually 
fatty diet, fat substances will be found in thc excrement. Indeed, a 063^ 
tain small proportion always so occurs. 

Of the salt substances usually occurring in the food, most disappear 
Sftlis ofLbc to- during tlielr passage tlut}ugh thc intestine, and hence but lit- 
teaUne. fl© jg found in the £eces ; more particularly is this the csao 

with those of a very soluble kind. (>f thc sulphates and cidoridcs of the 
food, not even a trace may occur in thc excrement. If thei»e gubstanoea 
should not be required for thc uses of thc system, they arc promptly re- 
moved by the kidneys, and in thc same manner arc disposed of any ab- 
normal suit substaiio^s which may have been purposely administered, as, 
for instance, iodide of ^wtassiutu. 

Thc gaseous contents of the inte-stinc originate in jjart from the air 
OiMtoftho that has lieen intro<luccd during the mastication of the food, in 
iniaitini:. p^yt j^m fcrmcntativc processes occurring after certain articles 
have been used which are only imperfectly digested, ami in fiart I'roni the 
endosmosis of gas from the blood through thc walls of the iutcsttual cap- 
illaries. As compared with atmospheric air, though tho oonijwfiition 
must necessarily be verj- ^•llrio^s, the intestinal gas shows a great excess 
of carl)onic acid and nitrogen, a diminution and sometimes even a total 
absence of oxygen, the presence of pure hydrogen, and of its carburets 
and sulphurcts. Thc quantity of this latter gas is less than might be 
expected from its odor, and, as would be anticipated from thc circum- 
stances, thc accumulation of gas is mudi more abundant in thc large than 
in the small intcsliiio. 



FORMATIOy OP P.CCES. 



I 



I 



Sduiiidt showf? that tbe intermediate circulation of water toward the 
I ilklestme is far more eonsiderable than its final excretion, and WaicrrumUb- 
|Mnounts in one day to nearly one fonrtli of the whole quan- ^0^*** '* ""** 
lity of watfT in the body. 

As ilic digcfltcil mass passes onward, driven by the peristaltic motions 
through the convolutions of the intestine, it becomes of a Comvl'-Krfmn- 
raore solid consistency, as the absorbents gradually remore ^ijnij JJ^ 
its liquid portions. Ry the time it lias readied the Cfecuni» tcou. 
the flame t-flect which arose in the stomach from fialivaiy digestion is 
repeated, for the traces of unabsorbed lactic acid canse nutritive diges- 
tion to be again feebly resumed, at all events in hcrbivorons animals, if 
not in man, whose c<ecum ia rudimentary, under the form of the appen- 
dix vermifonnis. From Peyer s glands a secretion lias exuded, which 
perhaps gives to the mass the characteristic odor it is now assuming, if, 
indeed, these organs arc not connected with absiorption. The eflctc re- 
Ruuns are finally voidetl as fa-ces, wliich, due allowance being made for 
the water tliey contain, amounting to about 75 per cent., may be rep- 
resented as averaging about IJ ounce |ier day. These excrement itious 
remains, colore<l yellow by the wloring niateriiil of the bile, are partly de- 
rived frrira the residues of the food which liavc been itnactt-d npon, and 
portly from the decay of t!ic system itself. The microscope shows the 
rcraains of cell membranes, and the walls of vegetable vas- FArmAUon 
cnslor tissues, starch gnmulcs, and chlorophyll, the relics of car- <*"*^'"*- 
tiUginous and fibrous tissues, »Iire*ls nf muscular fibre, fat-cells. From 
the digestive tract there have been derived mucus corpuscles, epithelial 
cell*, and the coloring matter of the bile. Perhaps, too, much of (he wa- 
ter which gives consistency to the fa?C03 has liecn derived trom the intes- 
tinal walls, for in qxiantity, under certain cireum stances, it may exceed 
the nmonnt that h:i.< liccn Ujicd as drink. 

In it* pa&<uigc through tlie intestine, that jwirtion of the bile which has 
not been absorbed undergoes considerable diangos, itsconju- piM{>i>earaoc« 
gnfrd ncids degenerating into dyslysin, which may lie rocog^ or liubUo. 
nize<l in llie ffeces, as is also the case vnth the modified pigmentary mat- 
ten ; the soluble mineral constituents arc. for the most part, absorbed. 

TIic reducing agencies in tlic intestine, and the manner in wliich sub- 
^UftcTj* can find their wav into the urinary secretion, is well inri.jrnuirf*. 
illoiitrated by the administration of indigo, which nndcrgocs la^^iUlfi^^^ 
dcoxidation into the condition of suboxide of isatinc, and will, Um. 
notwithstanding the agency of arlerial blood, apj^ar in that condition in 
the urine, to whicJi, ujwn contact of the air, it imparts a blue tint, becom- 
ing inon intense under a prolonged exposure, and eventually indigo-blue 
being deposited. Such u result not only shows how energetic are the re- 
ducing agoncies in the intestine, but also with wiiat facility very oxidiz- 



84 ABSOBFTION. 

able material may, tinder certain conditions, be exposed to arterial blood 
^vitliout oxidation. Yet that this want of action is wholly due to inci- 
dental circumstances is shown from the fact that salts of oiganic adds 
are much more quickly oxidized in the blood than they are in the open 
air. 

It is interesting thus to observe how the death of one part of the body 
Advtntace niinisters to the life of the rest ; for the nitrogenized and act- 
takea of the ivo principles of tho juices secreted for the accomplishment of 
p^iooto^ digestion are on the descending career, and are truly dyii^ 
guiize an- matter. The incipient stage of decay through which ibey are 
passing reacts on the food, and prepares it in a temponiy 
manner to replace those parts of the body which arc ceasing from activ- 
ity, and about to be removed. 



CHAPTER V. 

OF ABSORPTION. 



Double MediamtmJcT Absorption. — The LacteaU and Ve«u. — Lacteal Ahsorption. — Deter^ 
tioR of a ymiu.~-Analoffies ia I'lanU.— Introduction of Fat by the I'f/S.— 7%e Oigk,~ 
CmtstM of the Flow of Chyle. — Intermediate 0uages on its Passage to the Bhod. — Action o/* 
Peytr's Bodies. — Lymphatic Absorption. — Nature of Lymph. — Stmeture of the Lymphatic 
System. — Compariaoa of Otyie^ Lymphj and Senan. — FtmctioR of the Lymphatic System. — 
Production ofFibria. — Cataaeous Absorption. — Causes of the Ftoto of Lymph. — Apparent se- 
lecting poirer of tlie Absorbents.— Connection of the Lacteals and Lymphatics icith the Locomo^ 
tive and Respiratory Mechanism. 

The food, after digestion, tliough in the alimentary tract, is exterior to 
Double mech- *^® animal system. Means have therefore to be resorted to 
anism for ab* for its introduction into the circulation, and its distribution 
Borption. ^^ every part. This is accomplished by a double mechamsm, 

one portion of which is adapted to the digestion which has been going on 
in tlic stomach, the other to that which is completed in the intestine. 
The veins which are profusely spread on the walls of tlie digestive cav- 
ity constitute the former apparatus, the lacteal vessels the latter. 

Tlie lacteal vessels may be described as delicate tubes, conveying ma- 
DescripUon of terials absorbed from the intestine into the blood. Their 
a villus. mode of origin may be understood by considering them as 

projecting with a fine but blunt end upon tlie iimer coat of the intestine. 
This projection is covered over with smooth muscle cells and a plexus of 
blood-vessels, a continuation, as it were, of those of the mucous coat of 
the intestine itself; they are held together by connective tissue, and over 
that is cast a covering of cylindric epithelium. . This construction con- 



mSTRiniTION OP BLOOIJ-TESSELS TO THE ythU. 



85 



feti!iito3 what is called a villus, the stinpc of which is conical, or perhaps 
^cylindrical. The villus may then be r^arded aa a process of mucons 
smbraiie. 

Fig. 2s. ^iff' 23 is a section of the wall of the ilcam, 

a hcincr the ^nlli ; A, elands of l..ic- «. . * 

o ' ' o Stnicture of 

berkuhn ; r, muscular layer of mu- the iotcninol 
cous rncmhranc ; rf, foUiclca of aPcy- * 
ct's patch ; <?, rcniaindor of suhmucoua tissue ho 
iicath them : y, circular muscles ; ff A, longitn- 

W/jf /! / M \ r *^'"''* ™"^''^*'-'- (KoUikor.) 

rf ' ' L Fi^, 24 represents the distribution of LIooJ- 

vcsscla to the villi of the uitcatinc of the mon- 



fiOdlUMkn. 



5 * -^w^ *■ *\ 

DIitniKiUon of arterte* and velu on vUll of 

uonkvf. 



I key. The figure was drawn by the camera lucida, a a being the arteries, 
b b the veins. 

Tlie form of the villi diftcrs in different regions of the intestine. In 
the duodenuni they are less elevated, laminnted, and broad- ,. , „,. 
er, J'tg. 2o. In tuc jejunum, more projecting or cylindroiu, 



Fiit.^ 



Pia.^ 



— Tn**— of bloo<l-vr*M-u ou ibrt vtlU of tha Dblrlbullon ofUoaJ *'-wla on die tUU »f ihajt- 

/"i/^, 2G> In all cases, however, they are abundantly supplied with blood- 



86 



&TKUCTURK OP TUE WLU. 




vosscls. Tlicir epi^elinl covering of cylindroid cells i& shown in tlw 
sectional diagranif 7*^'^. 27^ a a i at If b is (lie origin of the lacteal aris- 
ing obscurely. _ Wji t». 

So amply are the ^illi supplied 
nith blood-vcssfls, that if, at'ler iii- 
Viriousoitln- jection with coloring 
Ik""^'?* matCTial, their cvUii- 

the vpitbuUl * 

cdU. dric epithelium be jxs 

nioved, they seem to be tinged all 
over. EacJi cell of the epithelium 
npjieura to be iilled witli granular 
matter, and to have a well-nuu-kcd 
nuelons. »Some anatomists assert ^^"'^ ^"" *» ■****"• '"*' <7""*»»m •p»t»»^"i>- 
that that e^d of these cells nearest tlie cavity of the intestine is in reality 
open, and in this manner they account for the ready passage of oil glob- 
ules into thera» and also for the appciirance of solid foreign bodies, as 0»- 
tcrlein obscncd. 

Though WIS have described the lacteal as a vessel projecting into the 
Orijfln of Uio interior of the intestine, it is by some viewed rather as a mere 
Uri«L excavation in the villus. The WIU impart to the raucous mem- 

l>Taiic an aspect sometimes likened to the pile of velvet. On an average, 
their number upon a square inch is about 10,000. The entire number 
of thcj>c organisms must, tlierefore, amount to many millions. At one 
time it was supposed that the lactcula ojjcn directly into the intestine — an 
opinion which is now universally aluuidunetL Tlic action of each villus is 
doubtle^H more complicated than i.-* gi-ncnilly n^preseiiled, for the organic 
fibre cells it contains give to it tlic power of executing rhythmic motions. 

AVhen tlic ojicrafion of the laetenl vessels aa al>sorbonts was first d^- 
•niclnctrai* tected, it was Itelicved tliat all nutriiiieiit is introduced bv 
»lTp'Ji4?uof *^'*^"^ means. But tlicre arc many animals wholly destitute 
aiMoqiiion. of this systcm of tubes, for instance, the invcrtebratos. Even 
in many fishes the villi arc absent. In such cases absoqition must nec- 
essarily be conducted by tlie veins. Moreover, though there are no lac- 
teals on tho walls of the stomach, nor, indeed, on that part of the iutes- 
tiiiul tul>e which is higher than the place of introduction of the biliary 
and jiancreatic ducts, there are many substances freely absorbed from the 
gastric ca^^ty when its pyloric orifice is tied. It has already been men- 
tioned that the Ptomach absorbs water with remarkable nipidity. The 
doclrinc- that the lacteals are the exclusive organs of absorption mu^ 
therefore, be abandoned, for it is plain that the vcnoua system particiiwtcs 
in this duty. 

The function of absorption has therefore to bo ejcaminod from two 
points of ^new. As there arc two digestions, one producing a perfect so- 



J 



ABsonmow w plants. 



8T 



I 



tation« amT tlic oilier an emulsioued, but not dissolveJ slate Con<liiions rf 
of the food, 80 tlicro are two absorbent systems, the loctcals '**^*'''*' •"''"*" 
ond the reinfl. The lactcals introduce Buch substances as ait: Uuo. 
not absolutely dissolved, particularly tlie oils and fats. The veins ap- 
pear to take up those substances only which arc completely ilbsolvcd in 
water. 

As in many othor cases in physiology, so in this, a correct interpreta- 
tion of the fiinctions of the animal mechanism mny Ijc ob- ., , , 

Absorption in 

taiticU by examining the corresponding structures and tunc- j.Unw, Uicir 
tions in plants. In the more perfect of these, the absorption •*"'"^s wp- 
of watery material from the ground, constituting the asccmKng sap, is 
brought about by the agency of collections of soft colls, ■nhich arc placed 
at the extremity of each rootlet. They are designated spongioles. By 
their action the fluid is forced up through the tubes of the sap-wood into 
the leaves, and there exposed to the conjoint agency of the sun and air. 
A cliange is thus accomplished, and, from being crude, it turns into elab- 
sap, and now descends through tlip bark, to !« distributed to every 
of Uie plant. Its ascent is caused by the cells of the spongiules, its 
descent by the chemical changes occurring among the cells which are 
found in the structure of the leaves. 

These cells — both of the roots and of the leaves — are far from eontin- 
aing their action for an unlimited period of time. At the most, their 
existence is transient. Those of the roots are gradually lost by decay, 
or converted into soUd structure, as the elongation of the organs through 
the ground goes on. Those of the loaves are equally transitorj'. At 
periodic iiiier\'al3, both in deciduous and evergreen plants, the fall of the 
leaf o<:curii — a new organism succeeding in another summer to make up 
for the one which has passed away. 

"Whatever nutrient material is taken from the soil in the case of plants 
is introduceil by the aid of a cellular structure, and the cells die after ao- 
compUahing their duty. 

Jt was once a saying among physiologists that the lactcols ore the 
roots of animals, and in this there is, in reality, a great deal Aii«1ok>- b*- 
of truth, for between the rootlet of a plant and the lacteal of lrj,°JjpUat 
an aniiuiU there is a conspicuous relation, not only in stmc- >^>*- 
tnrc, but oLso in function. As is seen in J^iff, 27, ujwn each villus of 
the intestinal tube there is a layer of cylindric cells, undenicath which the 
lacteal vessel takes its rise, for it docs not open by a ircc oritice on the 
interior of the intestine, but its tiask-shiipcd, loop-like, or con\'<dnted or- 
igin is obscurely seen in the m'uUt of the cells. The aspect which the 
villi present, from its doubtful nature, has led to the erroneous conclusion 
that, as soon as active digestion goes forward, cells rapidly develop with- 

tbe epithelium, and continue to do so as long as the intestine cuutains 




digutpfl matter ; tliat ihcy become torgitl with chrlc, and hare a duii)fr> 
tcr of altont the jT^nr o* *" ^^^^ ' *^"**' ** they aelcct material, iliey 
thnnv it into tiie luctcal tube, cither by bursting or deliquescing, and it 
the snmc time Kt tree broods of gcrraa trom wliich newcrells are developed. 
So fiir, therefore* a3 their duration is concerned, if this be their true histo> 
n*. they are even men.- tnuisiton' limn the corresponding cells of plants. 

That the lactcols nrc connected with respiratory digestion sccraa to be 
F«t ifl Intro- plainly indicated by the circmnstanccs of their occiureoce. 
u^u'iato*' ^^^^^ o^ them are fonnd upon the stomach, nor even on that 
the blood. part of the duodenum which is above the entrance of the he- 
patic and jmncrcatic ducts, but below that point they are scattered in pro* 
fusion all over the emnll intestine. The digestion of fatty liodics not 
taking pUcc untd the food luas gained the duodenum, vessels for the al^ 
aor^>liou of the emulsions to which ihut digestion gives nse are not re- 
quired until after that point is passed. Correctly speaking, however, 
the lactcnls aro only lymphatics which are taking up oil presented to 
them. In view of the use which the oils sobecrve in the animal economy, 
the lactcala are in reality an appendix to the respirator}' system. There 
can be no doubt that through their channel oils and fats, under the form of 
emulsions, are transmitted to the bloo<l. The analysis of the chyle .ihows 
that it is always ricli in fat, and, indeed, it is supposed by some physi- 
ologists that the objects just described as cells, surroumhng the origin of 
the lacteals, are nothing more than oil or fat globules accumulated there 
and waiting to bo taken up, or that the disappearance and exuviation of 
the so-called cells is an optical deception, due to their walla becoming 
pcmiciilcti with oiL 

The manner in which oil globules collect round the Tilliu I have re- 
marked OS being very strikingly displayed 
in the case of tlic gray squirrel after feed- 
ing on fatty nuts. As shown in J^iff, 38, 
the whole stnicture looks as if it were dis- 
tended with oil globules, It a, in the midst 
of which the origin of the lacteal, bbb, may 
be donbtfully and dimly discerned. 

Although it can not be admitted that ibo ^ 
Evuiktioa uid production and deliquescence 
J2i^,i,« of the cells of viUi is a demon- •««■ iB^tot •• •*«. 

vOU. stratcd fact, and that on this tlio action of the lacteals as ab< 

sorbent rcssds for the most part depends, the rapid evolution and disap* 
peaianoo of these cells is by no means a physiological impossibihty. Bot- 
anists assert that, in a single night, the Bovista gigantenm, a puff-ball, 
can devdop from a mere point to such a size tliat it must contain iiffy 
thousand millions of cells— a number that seems almost incredible. The 



r*ia 





THE MESENTERIC GLANDS. 



89 



^development of cells in the villi of the intestinal tuLc, in coimtleaa 
crowds, mar tJiercfore be willun the hounds of possibility. 

If t]u3 be tlic case, the cells wliicli thus come rapidly into existence 

[ in the villi appropriate those articles of respiratory food which are of 
imperfect solubility in water. To this class the oils belong. Each cell 
then, as it dies, yields up its contents to the lacteal tube. In the white 
fluid, the cliyle, which dows along those tubes, are muny pale or color- 
lesa corpuscles continually coming into existence. These seem to im- 
presa a cliango upon the chyle, and, to give a full opportunity for such 
action, th.it fluid is compelled to flow gradually through long and sinuous 
duuinels, for the glands in the mesentery may be regarded as convoluted 
windings, or rather plexusca of tubes, to which that particular form is 
given for the sake of closeness of i>ack^. From the enveloping ca|i- 
snlo of fibrous tissue of tlie glands thin sheets are projected, pj^rtum of 
and BO iulpmetted as to divide the wliole gland into many ilio miscDtcrie 
alveoli. These arc filled with a pu'py material supplied •** 
with delicate blood-vessels. The chyle either oozing through this ma- 
toial eventually escapes from the gland by the cflerent vessels, or makes 
the passage in its own tiiin tube. In reptiles, in which there are no 
such glands, the lactcals arc extended to a ven,'" great length. 

The manner in which the cliylo passes through the mesenteric glands 
is therefore exphiined differently, according to the view ^^ - ^ 
which is taken of the structure of those organs. If they (>fu»oiin*wiiift- 
aro considered as mere dilatations of the lacteal vessel, from "*^ ® *"' 
the sides of which partition processes are sent off, the interspaces being 
filled witli granular material, through which delicate blood-vessels pass, 
the chyle is to bo considered as oozing through this granular structure, 
and crossing directly in contact with it. But if'wc accept the doctrine 
that the chyle is conducted through the gland in a plexus arising trom 
the incoming lacteal, the granular material being outaidc, then the influ- 
ence of that material, in whatever it may consist, takes effect tlirougll 
the delicate walls of the plexus. The like remarks apply to the lym- 
phatic gUnds. Physically, however, the condition in both cases is the 
nme; the incoming liquid is simultaneously cx]x>scd in the gland to 
tiie infloenee of the granular pul]> and to arterial blood. 

The chvle, delivered into the lactpal tube, is propellrd by the conjoint 
action ofaeveral different forces. The constant accnmulation ^^^^^ ^f jj^ 
of liquid at the origin of the vessel produce* a pressure which tl"* ortho 
can only be relieved by motion through the tube, ari'l at tlie *' ^ "' 
OMRith, where the lacteal empties into a vein, as sooner or later ;:11 do, 
either directly or through the intervention of the thoracic duct, a suction 

[ieroe ia exerted on the contents of the lacteid by the passing current of 
renooB blood, upon the well-known hydraulic principle of Ventiiri, 



00 



KorioK OP THE cmxE, 




viilu» to tli« 
Uuoil-rcucliL 



f^fj nn. 



that if into a tuljc, a A, J^iy. 29, tlirongb which r current of water is stead- 
Fiif. 9. i\y flowing, another tube, c </, opeiu, tls 

more distant end being in communication 
with a resen'oir of water, n, tlirtmgh thia 
tube a currejit will likcwiHO im e.stabliisii- 
ed, and tijc reservoir be emptied of its 
contents. The cticct is still proatcr, 4S 
Bcrnouilli demonstrated, when the tnaio 
cnirent is Bowing toward the wide cod 
of a conicid pipe. Slorcovcr, the Inctol 
tubes arc elastic, and fnrnislwid wit h valves, 
which open to let the fluid jiass towanl 
the veins, but close in tlie opposite way. 
PHodiita ot rainrt. This vaKoilar mechanism renders available 

any pressure arising eitlier from the contractility of the vessels them- 
ICKUnbm far sclvcB, Of from tliosG various muacul.ir niovejnents, rcspira- 
*«MftiTlnc fQjj^ Qj. voluntary, which affect the abdominal walls. The 
nmnnej" of introduction of the great lacteal trunk — tho tho- 
racic duct — at the angle of junction of the left subclavian and 
jugular reins, is also very felicitoua, for the suc- 
tion force of those largo ressela is thcro cottjoiu- 
cd, and the clfcct is at a maximum. The con- 
trol of the blood motion on the chyle motion is 
obvious from this, that as soon as the circula- 
tion stops the chyle stops, and this not so tnach 
from tlie engorgement of the venous trunks, 
wliich renders it difficult for tlio chyle to make 
its way into them, as from the cessation of that 
tractile force, which solicits the chyle to move 
into tho blood. 

^7y. 30 represents tho position and course of 
the thoracic duct, and its nianncr of introduction 
of the chyle into the blood circulation. (Wil- 
son.) 

1, ,Vrch of aorta ; 2, thoracic aorta ; 3, aljdom- 
inal aorta; 4, arteria innominata, dividing into 
right carotid and right subclavian arteries; 5, 
Icil carotid; Cleft subclavian ; 7. superior cava, 
formed by the junction of, 8, the two %*enn-' in- 
nominatee, and these by the junction, 9, of the in- 
ternal jugular and subclavian on each side ; 10, 
the greater vena azygos ; 11, tho termination of 
the lesser in the greater vena azygos ; 12, recep- 




Tbo Ulitm^ diKiL 



d 



iimiODncnoN of fat. 



I 



I 



I 



I 



L 



tacolum cliyli, screrftl hiiiphatic trunks opening into it ; 13, llic iJioracic 
duct, dividing opix>site the middle of the dorsul vcrtebnc into two hrancli- 
cs, which soon reunite ; the course of the duct behind the arch of tlie 
aorta and left Buhclavian artery is shown by a dotted line ; 14, tlie duct, 
making its turn at the root of the neck, and receiving sereral lymphatic 
trunks previously to terminating in the posterior aspect of the junction 
of the internal jugular and subclavian vciu ; 1«), tlie termination of tlie 
trunk of the ductus h'mpliaticus dexter. 

As to the manner in which digested fat finds its way into the lactcals, 
it ecems to he aa follows: In the interior of the epithelial .- rofiba 
cells oil-drops are detected, wlitlc on the outer part the sur- itiiroduciiua of 
£ioe presents a j)carly aspect, from other portions of oil wait- **' 
ing to enter. By degrees, all the cells ujjon tlie exterior of the villus ex- 
hibit the same apimarance, the particles gradually finding their way 
throDgh tlic parenchyma of the villus, and so entering the lacteal tube. 
If, with some anatomists, we regard the lacteal at its origin as not being 
a true vessel, but only an excavation in that parenchyma, much of the 
obscurity which surronnda the explanation of ihe manner of the entry 
of oleaginous material into the lacteal is removed. If, moreover, witli 
other anatomists, we represent the intestinal end of the cyHudric cells to 
he iranting, and the cells themselves to be truly cu[>-shapcd forms, tilled 
witii ft peculiar secretion, through whicli fat particles and even solid sub- 
stances may pierce tlieir way, this likewise would remove much of the 
difficulty. But, after all, even if the genei-al opinion of the structure of 
a villas is adopted, that the lacteal commences with a blind pouch or 
l)Innt tube surrounded by a network of blood-vessels, and over this an 
epithelium cast, there being no mouths, or pores, or apertures of diseov- 
crable eize leading into the lacteal througli its own wall and enveloping 
structure?, we should also remember the extreme minuteness of the oily 
particles suspended in the chyle, and still more particularly that even 
this size, small as it is, is deceptive ; for, in passing through interstices 
too minute to be seen even by optical aid, the oil particles may bo press- 
ed out into long, thread-like forms, which, as soon as they escape into the 
free cavity of the lacteal, assume the sjilieroidal apjwarance by reason of 
tbcir own a»besion, just as a blood-cell can pass through a vessel of a 
diameter far less than its own by lengthening itself out into a linear 
shape, and reassuming its original figure as soon as it escapes from con- 
tinetnent and pressure* Though, therefore, the lactcals commence upon 
the intestinal walls as closed tubes, this, in reality, offers no obstacle to 
tbcir absorbing power when their molecular ])orosity is considered. 

J'erhaps this infiltration or intrtision of oily material is, to a consid- 
erable extent, aided by the presence of the bile, or, rather, its oily con- 
stituent. It is capable of easy demonstration that oil will rise much 



02 



CUAKQES OF THE CITTLE. 



higher in a capillary gliiss tube, the inside of which lias been coated otvt 
with biif*, tlian in the one which has not been &o prcpareii. 

The liquid which has been gathere<l into the Ucteals from the intes- 
tine pursues it.s codrsc to the veins, and ulliinatcly enters them. The 
special chnngcs wliich arc impressed on it during this paAsago will ncv 
be explained. 

The constitution of tho chyle ^iries with the physiological condilioas 
Constituiiun ^^ ^^'*^ system. After a period of iaHliiig it in colorless, and 
itn J Chang** in prcscnts the gcncrol aspect of lymph, hereafter to be de- 
scrilied, but during digestion it is a whitish milky tluid, 
whence its name. This niUkincss dej>cnds on the suspension of minute 
fat or oil globules in it. Their diameter is commonly stated at tbc 
3 whns ^^ *•" ^"^''** ^^ course, the composition of tlie chyle varies in dif- 
lercnt animals, and even in tlic same animal tinder different diets. 



1 liuna. 


Am, 


c«t. 


Mu. 


Walor 


9S5.00 
15.00 

.75 

3.*..(K) 

6.25 

8.(10 


002.37 

ac.oi 

.1.70 
S.t.16 

7.11 


905.T0 

as.7n 

1.30 

\ 48.00 

11.40 


9.30 

\ 70.B0 

10.80 
4.40 






Suits 


lOUO.lX) 


itwo.oo 


1000.00 


IMHI.OO 



With so many causes of variation, such a table as the preceding is 
only valuable as giving a general idea of the nature of the chyle. Wo 
learn from it that the predominating solid constituents are fat and albu- 
men. The percentage amount of the Jirst of these in the sample of hu- 
man chyle is very low, a fact duo to the circumstance that the subject 
from which it was obtained — an executed criminal — had eaten but little 
for some time before his death. In like manner, the chyle of horses 
which have been kept without food has been observed to exhibit a dim- 
inution of its fat to such an extent as to be less than one tenth of the 
nonnal amount, . It is to be remarked that the saline ingredients of tlw 
chylo closely represent those of the blood, both iu constitution and 
amount. 

The composition of the chyle varies at different points on its passage 
rotuiiiutionof to tho veins, there being a gradual diminution of the albt^ 
divie at van- ^„ j jjj^ increase of the Hbvin. After the passage through 

oas |»oint« iif iti-i 

luconFM. the mesenteric glands it becomes capable of coagtilation, 
and will separate into a scrum and a clot. Examined near the villi, it 
may be regarded as an albuminous li(iULd, in wliich are suspended glob- 
ules of fat of various sizes, down to the degree of minuteness just speci- 
tied. The nature of these globules is determined by the action of sul- 
phuric ether, which readily dissolves them. After passing tlirough tho 




J 



CHAKGE8 IH THE CHTLE, 



93 



mesenteric glands, the percentage amount of albumen tieclines, and tlie 
iat globules dimuiish in number. Simultaneously the special cells, to 
vhtch the nauie of chyle corpuscles is given, make their ftpt>earancc, and 
the lifjuid is now capable of coagulating, owing to the production of 
fibrin. Tlie-ie cliaractera become more strikingly developed as the cliyle 
•dvonccs in the thoracic duct. The chyle corpuscles are eventually de- 
veloped into red blood-cclla. 

It should be bonic in mind, in all discussions respecting the composl- 
tton of chyle in diflereut parts of its course, that it must re- . . jn^iMii 
Oeive transuded matters from the blood, and thai this must irjin^udaiion 
knorc particularly occur on its passage through the mnsen- '™™ ^i*" ''1"*>J' 
teric glands. Owing to tliis, it is quite probable that, even though there 
Bliould be an actual consumption of albumen in accomplishing the meta- 
morphoses which are taking place, the apparent percentage amount of 
that ingredient may increase by transudation from the blood. It a|>- 

rs to me r^uite probable that the alliuminous material in the lacteal, at 
ery origin in the villus, has Ijcen derived to quite as great an extent 
by transudation from the plexus of blood-vessels as by absorption from 
the digested food. 

Whatever may be the apeciid manner by which the fats pass from the 
intestine into the lactcaU, they have scarcely gained those snpoiiiiUatiwn 
Vessels before they undergo a change. The quantity of free oftb»>f»t- 
£tt diniinishcii, and that of saponiiicd fat increases; this is probably ac- 
oomplished by soda obtained from the blood. 

As to tlie fibrin, it can scarcely he supposed that the imperfectly co- 
egulable variety wi)i<'h the chyle contains should Itavo been DiirercoL-o be- 
derived by transudation tlurouyb the vessels of tlie strondy *7'T" ^^T^' 

\ •> O o J nl>rin snn 

contractile kind contained in tlie blood; and, in view of all cli,vlc-(ii.riij. 
the circumstances of the case, it would aj)pcar that the explanation wc shall 
Fiff.Ri. oftcrofitg direct origination from the 

chyle albumen by oxidation is coirect. 
Tiie ch^'Ie corj)ascles are readily 
distincuLshcd from the blood- ., , 
cells, not only bv tueu: white ohvio cnr- 
appciirancc, but'also by their i,;^;!:;;;'' 
1 form. They are spheroidid, n-nstnuon 
and either homogeneous or 
granular. Those of the frog ai-c seen 
in //>/, 31, at a a, sparsely scattered 
among the elliptical blood-cells. The 
photograph from which the engraving is 
taken exhibits nearly the average pro- 
diMnetom ' portion of these bodies in that animaL 



^^v 



C*>i^ 



I Chjrla ooTi^niclot vrVh t>hxid-eeUs, DignlAed SSO 



94 



CHTLE C0RPC8CLES. 



By the action of water, the nucleus of the chyle-cell becomes morediB- 
tinct, Its increased granular aspect making it more visible, as in /ly. 31 







Chjlt Mfpturlo* with arcllc arid, c)mg> 

toSadoevdiuMum 



By acetic aciJ tlie nucleus is greatly contracted, ns in J^iff. 33, and soroft- 
times even escapes from the cell. 

In embryonic life, the first appearance of chyle corjmscles comroouly 
coincides with a cliange in the arrangement of the respiratory roecluui' 
ism, as tlic closing of the branchial fissures, indicating a connection be- 
tween their production and the activity of interstitial oxidation. 

It has been previously stated that the bwlies known as Pcycr's glands 
v^'vct'n ImmIIm are to be regarded as belonging to the absorbent rather (liAn 
lucUa^ty^ '^^ digestive apparatus. In structure they are analogous to 
tvm. the lympliatic and lacteal glands, consisting of a capsule 

containing granular uiatcrial, in which loops of capillary blood-vessels 
are laid. From these proceed many lacteal vessels, ns may be very 
plainly observed during digestion. Their functions would therefore seem 
to be the submitting of tlic chyle to tlio simultaneous intlucnco of tlic 
blood brought by the arterial capillaries, and the pul]>y material or grart- 
ular plasma they contain. They are, in reality, dilatations of the al^rb- 
cnt vessels, accomplishing in a small space a result which would otljer- 
wise demand aver}' long lacteal tube, and probably not itnprcssing any 
other change on the chyle than that which would luive occurred in sadi 
a lube, if of sufficient length. 

It is not possible clearly to understand the ftinctiona of the laelcals 
Stnioiuro ind *'*^^o^* ** description of the structure and functions of the 
fuiinionsdftho lymphatics, for these vessels consjjire in their action. 
■*""'' "'^'■^ Anatomical, chemical, and physiological considerations 

lead ns to conclude that the formation of the LYwrnATlc frrRTKM ia 
closely allied to that of the lacteai- The two classes of vessels moke 
their appearance together in fishes; tlie h-mphatics originate in a net- 
work of delicate tubes, but arc disseminated tlirough all the soft tissues 
except the nervous, and arc found especially in the skin. The fine ini- 



PROPERTlEa OP LTMTIL 



95 



\ tubes gradually coalcscf, producing those that are of a larger diaroe- 
cr, aiid tlie^jc pass tlirougli glands, which might indeed be regarded as 

ere plexuses, and eventually empty into the veins. 

A few luinates after it hjia l>ccn drawn, the lympli coagulates into a 
iolorless clot, and tlicii exhibits contraction. Compared with proprniu or 
(lood ill like circumstances, llie clot of lymph ia small in re- '."uii.u. 
ation to the serous portion. In other respects there is a general resem- 
>laiice between lymph and blood free from its red cells, the iibrin and 
be albumen being apparently the same in the two cases. The saliuo 
Donstituents are not only the same, but bear the same ratio to one an- 
other in the two fluids. Their absolute percentage amount diHers, be- 
lose the lymph contains a larger proportion of water than tlic blood. 

The h-mph arising, as we sball tind, by transudation from the capil- 
.rics, mast obviously vary in difTcrent ports, tliosc parts taking from 
ho blood the materials they re^Luiro for their nutrition, and yielding to 

tlie products that have arisen during their waste. Whatever in this 
Banner changes the eompo-sltion of the blood, must also occasion a change 

the transuded liquid. Tims Sclmiidt has shown that protein bodies 
nnsadc through the capillaries of the pleura most copiously; through 
ho3c of iho peritoneum not to half tliat amount ; tlu'ough those of tho 
iraiu and tliosc of the subcutaneous areolar tissue to a less and less cx- 
BoL Kot only must the material tims oozing from tho capillaries vary in 

ffcpent regions, because of variations in tho mechanical constitution of 
hose vessels, but it must also change even in tho eamo locality, througli 
rxDporary accidents, such as changes in the velocity with which the blood 

flowing. An attcmjit has been made to show that the transudation will 
riciiest in albumen as the blood current in the capillaries is slower. 

When the contents of the lymphatic vessels arc submitted to analyst 
kDd compared with the chyle, a striking difference is appar- c<inipo*iii(>uof 
nt. The chyle contains, as has been already stated, large b •"?'■• 

t variable proportions of fat or oil in an extremely subdivided state, 
rom which the lymph is free. The leading solid constituent of the 
^mph is albumen, and this indicates the use of the system. 

Cbmpo*ition <if Lymph. 





Uonr. 


Am. 


Mm. 




.09 

J- S9. 1 1 

4.88 
5.92 


B6d.86 

1.20 
13.00 
15.59 

6.85 


tmi.oo 

S.60 

27.M> 

S.IO 


Pm 


Fibrin .«.«, 




tUl8 „ 


1000.00 


1000.00 


1000.00 



The functional coimection between the lactcals and lymph vessels is 
sery well illustrated by the following analysis, which ex- Pauinffchylo 
libitc the composition of diyle obtained from tlic thoracic ^ >/i»pt>- 



96 



COStPAIUSON OF UllPn, CinXK, AXD SERlIt, 



dact of a man vrho died from sof^euing of tlie brain, and who took noth- 
ing but a little water for 30 hours preceding Uis death. (L'Hcriiier.) 

TVwcr ^ tt24.a6 

FkI » » &.I0 

ribrU 3.20 

Albameti „ €0.09 

Balls „ 7Ja 

1000.00 

The constitutiou of the chyle so nearly approachcH that of the lym^^l 

Comparison of *^"' ^**^ ^^ authorized to conclude tlint, daring fasting, 31^^ 

... 1.1. '.1 1 1.1 1* '*nn«o In 



cliyU. 



Ltcteols transmit lympli, and tlic conclusion gives force to 
tbe observation ali-eady made, that the albumen of cbrlc is 

derived rather from the blood capillaries than froni the digested food. 

ContMri^n of *-^" comparing together tlie salts of the serum of the blood 

tbo lymph atid and thoso of the lymph as obtained from the horse, they ip- 

"*"*"* pear to coincide. 

Suit* ^ Scrum a$td LgmjA. 





Srniin. 


Lruiph. 




l.l.tO 
.Ull 
.IIS 


4.I3S 
1.13ft 

.an 

.lao 










£.611 


&.6II 



From the indications presented in tljese tables, there can be no doubt 
Officeortha *^*"' *^*® office of the lymplialica is to collect the albuminous 
■rmphftUc svs- matters which have every where transuded from the blood- 
'«•»• vessels, or been set free by changes going on in the soft 

parts. Sucli matters, though they may bo regarded as being in one 
sense dead, arc yet as applicable for the fiu-thcj* support of tbe mechan- 
ism as are the albumenoid bodies introduced as food, and said to be 
taken up by the lactcals. The last table shows that the lymph is really 
nothing but a diluted scrum. A mechanism is therefore resorted to to 
turn this collected albumen into fibrin, and thus arises a lymphatic gland 
— a contrivance which tends greatly to compactness. This structure is 
Ftmctarc of *^'*^ counterpart of the mesenteric or lacteal gland. It may bo 
l,vai)>baiic described as originating from the coalescence of two or three 
*' " ' lymph vessels, which, casting off' their external coat as they 
enter tlie gland, anastomose with one anotlicr in various ways, so as to 
fonn plexuses and convolutions. The capsule of the gland, strengthen- 
ed by the coat it has received from the entering vessels, sends forth par- 
lilion-like ]>rocefl3e8, which dip down into tbe grayish pulpy material 
filling the interstices. On their emergence from the gland the vessels 
necovcr from it their external coat, and, during their passage throngh it 
in their naked state, blood-vessels arc distributed upon them. Tlie ob- 



THE LYMPttiTIC 8TBTEM. 



97 



rtsr-u. 



I 



ject of tho arrangement secma io lie to submit tlie liquid contained in 
the lymph vessel to tlic action of llic pulpy material of llie gland and ar- 
terial blood under the moat fivorable circumstaiiceH, the thinness of tbc 
wall and llio convolved plexus being well adnjitcd to that end. 

/Vy. 34 illustratea the IjTiipbat- 
ic3 of the large mtcstinef the ad- 
joining parts being cnt or displaced 
to display tiicm ; a, a, ascending 
and transverse colon drawn aside; 
A, d, descenduig colon and its sig- 
moid flexure drawn aside ; c, co;- 
cum ; (I, stomacli ; Cj duodenum ; 
/", jejunum cut ; ^, A, i, lynii)hatic3 
and their glands. In sucli an ar- 
rangement as this, the lymph is far 
more perfectly cx])0sed to the in- 
tincnces to which it has to Iw sub- 
mitted tlian it could possibly bo in 
straight tubes. In reptiles, how- 
ever, this package is not resorted 
to, and the tubes, being spnad out, 
give the false appearance of a great- 
er development to this sy.-'tcm than in the higher tril)CS, In the mam- 
malia, according to Professor Goodsir, wherever the lymph tulie enters 
the gland, it changes its internal constitution, losing the scnle-likc cover- 
ing that its inner cont presented, and offering a numerous development 
of nucleated cells, many of which adhere to the membrane beneath, but 
maiiy float away and drift w^th the lymph in its course. There is a 
coDStant rcjirodnction of these organisms, and they seem to be comiected 
with R change in tlie nlbumcnoid constituent of the lymph, pj^^jy^u^^j, ^^ 
turning it into fibrin. And thus, if examination is made of fibrin in K-mph 
the lymph Iiefore it enters a gland and after it has passed s"*"*!*- 
through, in the former instance it seems to ditTcr but little from the liquor 
sanguinis, or serous portion of the blood, as lias been already shown, but 
in the latter fibrin begins to abound. 

Professor Goodsir'a view is represented in the diagram, J^irj. 35, show- 
^'9- 20. F'ff. 30. jng tjie gcale-likc cp- 

oSS&^S^^ ithclial cells of the 

lymphatic tube chang- 
ing into the nucleated 
cells of the gland. 

OtaCBtDDrBlrmpligluid. KTolntinnnferllMlalrnirb^liilu]. -f^if/- 36 tllustratCS 

the generation of broods of ceils, some being attached tmd some free. 



LTBTplMtks of the lu^ IntotUnc, 




I uio gw 



a 



98 



PBODCCnON- OF nURIX. 



Some chcmUts, adopting Oie views of Liebig respecting the essential 
nhrin not on difference l)etween blood fibrin and muscle fibiin, look upon 
.ffcto iKxiy. iiig fonucr substance, not as a histogenetic, but as an effete 
body, a conclusion wliicU, of coutfc, would bavc an important bcariiig 
upon the interpretation of the function of tlie glands as here given, as like- 
wise upon that in the corresponding case of the chyle The weiglit of 
physiological evidence is, liowcver. so strongly against this doctrine, liuit 
tre arc constrained to retain the old one, and therefore to regard the pn- 
duction of fibrin as one of the important duties of the lymphatic systcoi. 

Tho absorbent vessels, whether lacteals or Ijmiphatics, have therefore 
lu mode of * common duty of changing albuminose or albumen ioto 
prtKioctioo ttDd fibrin, and thereby of compensating for the constant waste of 
'*"*'*'"• * that substance wliich h going on in tlic wear and tear of 

the mnscalar system. The constitution of tho urine proves tliat the 
amount of muscular fibrin destroyed in short periods of time is \txy 
great. We can not estimate the liourly consumption at leas than G2 
grains. Such a wa^tc must demand an cijuivalcnt compensation, if 
the animal meclianism is 1o be kept tip unimpaired, and cvety cam is 
therefore taken to omit no means which may incidentally offer for hua- 
banding tho necessary materials. The action of the lymplutics ilhu- 
trates this principle significantly. Passing through all the soft solids 
where exudation of albumen from tlic blood-vessels can take places they 
collect tho materials tlmt would otherwise go to waste, and add thereto 
many of tho products arising from the disintt^ration and decay of the 
soft parts themselves. Receiving all these, they transmit them throi^ 
their windings iu the glands, and thus submit them tu tlio action of the 
innumerable cells which arc there coming into existence. As in the egg 
of a bird, in which, as the albumen slowly disappears, tho muscular tis- 
sues of the young chicken arise, so here tho serous portion disappears, 
and fibrin comes in its stead, and this is hurried forward to tho torTcnt 
of the circulation, and tlirown into tlic blood-vcsscb, to be by them dis- 
tributed to all parts of the mcchauism, wherever the muscular tissues are 
in want of repair. 

But, besides this fiinction of tho elaboration of fibrin, there can be no 
Cutuituua qQCStion that the hinphatica have otiicr incidental uses. 
UmpiuiUc ah- Mony facts are known which prove that those of tJie skin 
•or]. Hill. cjtert n powerful agency in alworlting liquid material. Thus 
a person who has abstained t"ron» water will, after lie has immersed his 
botly in a bath, not only find his weight increased, but tho sensation of 
thirst abated. Instances of the kind are on record where sailors, in open 
boats >Wthout firesh water, have assuaged the torments of thirst by im- 
mersing their bodies in tho sea. Nay, it is o\'en asserted that in certain 
conditions water may thus be obtained fiom the atmospheric air, and in 



BELECTINO POWEH OP THE ABSOnUENTg. 



such cases every thing points out that the l)-mphatic vessels are the 
iTcnues through which the hquid 'la introduced. 
In wliat niaiuicr does the lymph move? lu reptiles there are found 
are ternioJ lymphatic hearts, which are nicrely dilated caosoofthe 
ions of a tube cxhihiting pulsation. Of tlicsc» in tlio ^*"' '*'' b'm'^ 
g, two pairs may bo discovered, one behind the iiip-joint, and situated 
lo superficially that the motions can Iw plainly seen ; the other is at the 
interior part of the chest. The pulsating movements of these on^ans, of 
loarso, impel the liquid acted on in the direction determined by the valves 
rilh which the vessels arc so profusely suppltedi that is, to the general 
ttrcuiation, and llie lymph finally enters the blood-vessels. 

But in the liighcr tribes these organs of impulsion arc absent, and the 
arcuUtion through the vessels is determined by the agencies mentioned 
n the case of the lactcals. 1st. Hy the constnnt accuinulation of Hquid 
it the origin of the tube; 2d. liy every muscular movement, citlier vol- 
kntaTy or involuntary, which produces a compression of the tube, the 
lalTCS all opening one way, and therefore causing the included liquid to 
m»B in ono direction only ; .3d. By the exhaustive action at the moutli 
if the lymphatic, arising from the passage of the blood. It ought, per- 
laps, to be prominently pointed out, as f»elonging to the second of these 
■uses, that the puUation of the arterial trunks adjacent to any lym- 
balic brings the jrower of the heart itself into operation in an indirect 
rar. 

Though the absorbents will receive many different bodies and transmit 
|iem lo the vcbis, the action does not take jihice in an in- ^-p^n^j ^ 
Hiscnminate manner. Certain substances, such as the fats U-ctiag power 
nil allmmen, find a ready entrance, but admission to others * *"''*"'*- 
wholly denied. Thus it has long Iieen known that if coloring matter 
i introduced into tlie intestine, it by no means folloivs that the cliyle 
iU be tingc<i If an animal be comj>elled to take litmus-water, the 
liyle will still be found colorless or white. On such facts was founded 
he old doctrine tliat these organs possess a low Bj)ecic3 of intelligence, 
istiugoishing among different substances, permitting some to enter 
kBB, and refusing a passage toothers. Many years ago I showed that 
lese fanciful cases are capable of a simple physical explanation. Thus 
fixmd that if blue litmus water was tied up in a bladder, or a piece of 
eritoneum, and sunk in a veasej of alcohol, though the water would rap- 
Jly infillrate into the alcohol, the coloring matter would be stopped just 
it is in the intestine. But, in reality, there is no need of such experi- 
BcntB to satiafv tis of the fictitious nature of this selecting jwwcr. If 
fill a lamp half full of oil and half of water, and immerse in it a wick 
img enough to dip into Ijoth, if the %vick be prcNnously soaked in oil, it 
ill withdraw from the lamp oil alone, and continue to do eo until tlie 



100 FOUMATIOX or FIBRIN. 

lamp ocaaes to burn ; but if it be first Boakod in water, it will whoUv 
refuse to take the oil, and rcmoro the water alone, until &U ia escaped It 
evaporation, iiut did ever any ouc impute to the wick of a lamp a. 
power of intellectuality, no matter how obscure, or suppose that tlicr? 
is any thing mysterious in such a selecting operation t A perjwtual refer- 
ence of the most common facts to mystexious agencies liaa been the grett 
barrier to the ad\-ance of medical science. This system was intiodnced 
by the nlchemi.stA and quacks of the Middle Ages, and even now it will 
tnkc many books nnti many yeara bdbre physiology can be rescaed from 
such visionary theories. 

From the [X}int to which our descriptions liave brought us, wc ha^-o 
Conntrtion of *° regard this part of the absorbent mechanism as connected 
bct«nia «u4 witb two gTcat animal functions, motion and TCS{)iration. 
wul'moii^ iJoth its divisions, tlie l_>-mphatics and the lacteals, in ptepor- 
an.i n<f>{>irn. ing fibrin from albnmcn, moke provision for the repair of the 
muscular tissues, and arc therefore to be regarded as a portion 
of the motive apparatus. But the lacteula arc charged with a fiulhcr 
duty, and in o double manner arc cotmectcd with the respiratory mechan- 
ism, for they nut only introduce fats into the system, but give origin to 
the cells of the blood, wlucli arc the carriers of oxygen, 

Wc may therefore close this chapter with a few remarks, Ist On the 
eoimection of the absorbent system with tJio provisions for motion ; 2A. 
On its connection witli the rcs])iratory fuuctiuu, as more particularly dis- 
played by the pre})aration of blood-celU. 

1st, The connection of the al^sorbent system with the provisions for 
motion is through its function of preparing fibrin from albumen. 

From the membrane which lines tlie plexus of tubes of which tlie xdc^ 
FtbHcntion enteric and lymphatic glands are comi)Osed, crowds of nucleated 
of flbrln. cpiig ^^ continually arising. As to the function of these ocUs, 
there con be Little doubt that it is in part to effect tfie translation of a 
l^ortion of all>umen, wliich Ims been introducexl along with the oil glob- 
ulee, into fibrin, and accoixlingly wc find that the chyle, analyzed at dif- 
fietent parts of its course, yields dilTercnt products. As haa been stated 
already, intercepted before its passage tlu-ough these glands, very little 
fibrin is found, but collected from |>oints beyond, the quantity of fibrin 
steadily increases and that of ntlmmen declines. The plexus of tubes 
lias therefore for its object to expose its contents to the infiueneo of the 
cells. 

Now wluit are the chemical conditions under whidi the Iransmntation 
of albumen into fibrin takes place? The problem is most clearly pre- 
sented in the co^e of the incubation of a bird's egg. The white of the 
egg, consisting ciiicfly of albumen, gradually loses that form, and passes 
into the state of fibrin as the development of the muscular tissues of the 



A 



FORMATION OF BTjOOD-CELLS. 



101 



I 



I 



L 



young diickcn is cfii^cteJ ; but tlie clmnge can not take place except ox- 
ygf^n be received thnnigh the shell ; and, indeed, in all cases in wliich al- 
bumen losses into fibrin, it does 80 only in the presence of oxygen. 

Bat in the ease of the absorbent glands, from what source does the 
i«f|uL$itu oxygen conicl" These glancln have just been de- Manna- io 
scribed na plexuses of llic absorlxMit tubes, among the rami- **'''* oxrRcn 
fications of which arteries and veins are abundantly distrib- the making of 
ottHl, the blood not getting access to the interior of tlie ab- **''""■ 
florliont, bat running in its own vessels, as it were, side by side, and 
branching on the naked walls of the plexus ; and, just as in the placen- 
tal circulation the arterial blood of tlie mother vivifies or furnishes oxy- 
gen to the f(L't:d bloofl, so in this instance the arterial blood enables the 
crlls to disdiargc their duty of converting the albumen into fibrin, which 
passes onward to the general circulation for the renovation of the muscu- 
lar tissues. 

Since the hourly consumption of fibrin may be taken at 62 grains, 
the quantity produced bv tlie action of these cells must be the same. 
Wc may llierefore affirm that the fibriu-producing meclianism yields 
about one grain iu each minute of time. 

2d. Conteniiwrano^ualy with the elaboration of fibrin is the develop- 
ment of the proper chyle corpuscles. Through the evolution Fonnitionof 
of these and the absorption of fat, the chyle vessels present a i'l«»<i-<»*i«- 
connection with the rei*|>iratory apparatus. 

If any weight is to be given to the ahcws of Aschorson, the occurrence 
of fat globules in the chyle is essential to these cellular productions. 
Hii (bund that when globules of oil are placed in a solution of albumen, 
tliey become coated over wilh a film of that substance in a coagulated 
state, and hence was led to infer tixat this is the starting-point of cell pro- 
daction generally. 

The cliyle corpuscles arc tlie embryos of the true red blood-cells, the 
latter being derived from them by gradual development. As will appear 
more in detail when wc come to the description of the blood, in vcrte- 
bratcd animals there are tvro distinct classes of red biootl- -, , 

celts, which appertain to distinct periods of lil'e. The first, foniMofbiooi}- 
whicli are found in man previously to the time of formation ** ° ""*"* 
rf the chyle and lymph, art* nucleated, and have the power of reproduc- 
tion by fisBuring of the nucleus. 

But a distinct set gradually replaces the preceding. These cells have 
no noclcua; they are flattrnc<l, bi-concavc, and in man circular. They 
poaaflss no power of reproduction either by Assuring or otherwise. Their 
origin is firom the chyle corpuscle^ the granular interior of which clears 
op, and is snccceded by a deep red tint. Tlie transition firom the first 
to the second of these forms takes place at an early period, and may be 



Ml 



102 ABSOHPTION BT THE BLOOD-VESSELS. 

regarded as complete in the human emtryo of two months old. After 
that time blood-cells are generated upon the second plan, from the chyle 
corpuscles alone. 

It is a significant circumstance that this transition from the reprodnc- 
tivc to the non-reproductire blood-cell is coincident nsnallj' with the dis- 
appearance of the external branchite, or the closing of the branchial fis- 
sures. There can be no question that the destined ftmction of the per- 
fect blood-cell is the introduction of oxygen to the system. In their or- 
igin and in their object they are therefore in relation with the respirafoir 
mechanism. 



CHAPTER VI. 

ABSORPTION BY THE BLOOD-VESSELS. 

Proof of AhsorptioH 6jf the Blood CapiBanes. — Occur* om a j^rical Neeessity. — Aotare of Cup- 
ilLtry AttractioH. — lu I^tntomena in the Bist and Deprt*»ism of Uqmd*. — Comtitiama fv 
proditnng a Fhw in a Cafnliary Tube. — Postage of LiqttidM through miniUe Pore*. — Genera) 
I*rojtimtioiu respecting GipiUary Attraction. — Endotmotis and Exotmous. — 7%gr dtpemdon 
Cii/nliary Attraction. — Porce agavat ichich these Movement* wtay tate place. — ISnttrtttioma e/' 
aeUOv^ J^wer. — Gattrai Ctor o/the entirt Ftmction of Abtorption, lacteal and vatotu. 

That the blood-vessels of the stomach and intestinal tube participate 
Snbsunces are in the function of absorption is demonstrated by many dif- 
SeT^ «i>- ^«""* ^*^^* Medicaments placed in the stomach after its 
iiiariea. pyloric orificc has been tied will produce their specific effect 

almost as rapidly as under natural circumstances ; and, since there arc 
no proper lacteals upon that organ, and its 1^-mphatics seem to be inade- 
quate, tlie absorption of these agents can have taken place through the 
blood-vessels only. 

This conclusion is substantiated by an examination of the blood of 
the gastric and mesenteric veins. It varies with the stage of diges- 
tion and the nature of the food. At first there is a general lowering of 
the percentage amount of the solid ingredients, this being evidently the 
result of the absorption of water. At a more advanced period, the rela- 
tive proportion of albumen, or rather of albuminose, rises, and along with 
it the extractive, gelatine, and sugar increase. As with the chyle in the 
lacteals, so with the blood in the mesenteric veins, coagulation takes 
place imperfectly, or perhaps not at all. It is stated that the mesen- 
teric blood of a fasting animal does not differ from the ordinan' venous 
blood. 

The i>osition of the blood-vessels, both on the mucous surface of the 
stomach and particularly on the villi of the intestine, is favorable to the 




I 

I 



harge of this function. The terra vcnoiia absorption, employed to 
tnr&s it, ia perhaps somewhat incorrect, since there is no reason that a 
renous capillary should have any advantage over an arterial one in this 
respect. The rapidity with wluch substances in a state of solution are 
lAkcQ up from these cavities has been wcU demonstrated by such in- 
stances as tliosc of the detection of the fcrrocyanidc of potassium in the 
nrinc within 2^ minutes of its having been deposited in tlic stomach, or 
by the ileath of dogs in a similar short period after strong alcohol liad 
been administered to tliem, their blood being found to bo charged with 
that combustible subslauce. 

Among substances thus finding their way into the circulation by di- 
rect vascular absorption may l>e enumerated such soluble salts as Iiavc 
little affinity for the tissues, mineral and urganie acids, alcohol, ether, 
volatile oils, vegetable alkaloids, and coloring matters, as those of rhu- 
barb, madder, gamboge. 

In fiict, if there were not these physiological considerations, we should 
Imve to admit absorption by the blood-vessels as a mat- AiworpUon by 
ter of uhvsical necessity ; for, under the circumstances of *''* *'l"*''-»«^ 

, . . . , , , ,, , wUoociir»«»o 

tiicir situation, tney must take up soluble matters presented j)byiic«i mcc*. 
to tlicm. Through the \H)Tt's of their delicate structure sub- *'*^' 
stances in the liquid state will psss to mingle with the blood. 

Though we have treated of respiratory or lacteal absorption as specif- 
ically distinct from absorption by the blood-vessels, the circunii^tiuices 
here alluded to evidently point out that the resulting action of the villi 
of the intestines is of a mixed kind ; for, though the cpitheJia] ci^lls and 
the commencing pouch of tlie lacteal mny exert a definite influence, the 
network of blood-vessels which lies immediately beneath the epithelium 
must be engaged in precisely the same maimer a:i the network of blood- 
Tesaels between the gastric follicles. The permeation of the walls of 
these tubes by substances In a state of solution is dependent, as wc arc 
now to sec, upon a purely physical principle, which is just as a])plicablo 
in tho one case as It is in the other. The leading solid ingredients of 
tlio chyle being fat and albumen, the former is perhaps introduced I'y the 
proper lacteal structure, and the latter, taken up by the vascular network, 
exudes tn part again from it into the lacteal arrangement. 

In the case of absorption, as in that of respiration, hereafter to be de- 
scribed, there is a physical principle in oi)erution which it is neceasaiy 
to understand. I shall proceed to explain it on this occasion as far as is 
needful for the present pur]iosc, and complete the description in the chap- 
ter on the lunction of respiration. The peculiar views here set forth, 
so far as they differ from those ordinarily expressed, I believe to bo 
warranted by my own experiments elsewhere published. 

The absorbent action of the blood-%'essels depends on the force known 



104 



CAPILLARY ELE\ATIOXS AND DEPI 



Fiff. M. 




C«riiUrT among pli^rsical writers ns capillart AlTBACnoN*. Its nature 
atinciiun. j^jjy i^ Ulustratwl as follows : 

If a piece of glass be laid on the BUiface of quicksUvcr, it is so powo 
fully attracted thereto a? to require tJie exertioa of considcmblc force to 
hSi it off. Natural philosopbcrs generally regard tliia as a force sui ge- 
neiiB, and speak of it under the title of capillary attraction. I beliere it 
is nothing but an ordinary elcctricid phenomenon, since, if the glasA be 
examined, it will be foand to be in a positively electrified state, and the 
quicksilver negative, and under the general law of electricity, known as 
that of Dufay, attraction must be llic result. 

If the glass bo laid upon the surface of water, there is 
an attraction as Ijeibn*. On lifting it, however, there is 
no clcctricnl manifestation. The rca.<on of ttiis is plain. 
Oa examining this glass, it will be found that no true 
separaliun of it from the water has taken jilacc. A film 
of water is still attached to it, or, in other words, it is 

If a slender glass Ui\A\ h, Fifj. 37,Ik> dip|)edinto a liquid, 
Eisvntinntnd o, (2, which coii uol wct it, OS, for example, 
S^jdr'nTup. n^icksilvcr, the liquid is depressed as at c^ 
liUrj- iube». and does not rise to its proper hydrostatic 
kreli or, perhi^s, altogether refuses to enter the tube. 

JV-ss. If a slender glass tube, KFlg. 3S, be dip|Kti into 

a liquid, a, «, whicii can wet it. as, for example, water, 
the liquid at once rises in the tube, as at c, to a height 
which is greater in proportion as the diameter of the 
tube is less. It is this phenomenon which has given 
the designation cajnUavy attraction^ because it ia 
best seen in tultca as fine as a hair (capiUiis). 

Now if tlicre l)c a tul>o of such a diameter that it 

could thus lift water ten incites, and it be broken off 

BO as to be only six inches long, we might inquire 

whether the water would overflow from its top, or 

simply remain suspended. 

Mathematical considerations as well as direct experiments prove that, 

in such a case, there would lie no oveHlow. A capillary tul« under 

these circumstances simply lifts the water, but can not produce a contin* 

uoua current. 

But if a removal of the water at the toji of the tube takes place in any 
„ ., , , mnnner, as, for instance, by ev«iiomtion, or by beinij dissolved 

Comlilloni" for ' . . • 1 1 «,, 

l.rf..luciiiB» away, tlien a contmuona current is pro<mced. This fact ex- 
*'*^' plains the phenomena of endosmosis, presently to be do- 

scribed. 






Elevation of ft wculn|[ 
U<(Ui<l. 



J 



PAS9AGC OP WATER THROVGR CBEYICES. 



105 



As illnstrative of the piwluction of a continuous flow, wc may cite the 
case of a spirit-lamp, t!ie wick of wliich may be rcgardoJ as a bundle of 
capillary tubes. If the cover of tiie lamp be taken oif, all the spirit will 
pass up the wick and escape by evaporation. Or in an oil-lamp, the wick 
of which liceomcs readily saturated with iho liquid, but never cxliibits 
any overflow, on the lamp being kindled, the oil is bnmed oflT, and a cur- 
rent is Rt once esfablislicd. 

I have shown that water will pass tlirough a crevice, the width of which 
is less than one haif of the millionth of an inch. Pores or Liquids psM 
crevices of such a dimension are invisible even with a micro- ^^^^tHt^ 



Boope^ 



ic«u or pores. 



The evidence in proof of this is very readily obtained C3q)enmcntally, 

^■^- If wc take a convex lens, tz, a, of 

^^^^^^^^^^^^^^^^^ ^ou}^ raditiH, and i)lacc it upon a glass 
iH^^m^^^^^^^^H^HHI^ plane, fi^ h^ there will Itc seen at the 
fMwreofwBtexuiroiiKhAcrcYin. point of contact, c, on looking down 

upon the arrangement, a black spot surrounded by a series of variously 
colond concentric circles, the appoiu-aucc l>eing well known among op- 
tical vrittira under the name of Newton's colored rings. At the point 
o£ apparent contjict, c, the lens and the plane are, as Newton lias shown, 
a distance apart of about the one half of the millionth of an inch, and 
from this central point, proceeding outwnrdly, the distance between tlie 
glaaaes, of course, increases. If any wlicre at the outer portion a drop 
<tf wal«r be introduced, it extends itself instantly across kII the colored 
rings, reaching even across the central black S{>ot. 
H The three following general propositions present those phc- Genowl propo- 
■ nomcna of capiUary attraction which arc most interesting in [i^^^pJiJJ!^'^ 
a pbyaiologicol point of view. »nr«ction. 

lat. If the force <)f attraction of the particles of a solid for those of a 
liquid be not c«|uaI to /*/7//'the cohesive force of tlio latter for each other, 
the lirpiid will refuse to pass through a pore of that solid suhstance, and, 
is a capillary tube consisting of it, will be depressed below its hydro- 
Static level. 

2d. If the fortM of attraction of the particles of a soUd for those of a 
liquid exceeds Art//" the cohesive force of the latter for each other, but ia 
not equal to tlie whole force, the liquid will pjias through a jwrc of tluit 
solid substance, and, in a cipillary tube of it, will rise above its hydro- 
static lovol. 

3d. If the force of attraction of the particles of a solid for those of a 
Itqnid exceeds the whole cohesive force of the latter, chemical union bo* 
twecn them enraea. 

It would not be consistent with the plan of this work to offer a dem- 
I of these propositions ; nevertheless, they are capable of rigoi^ 



106 



Bin)0ffil0ST8 AKO' 



F-.c. *\ 



ous mathematical and physical proof. TIte %*iewfl I am here presentng 
enable os to include tlie pressores between solids aud liquidia, the rise or 
depression of liquids in capillar}' tubcs^ oud the phenomena of cbenic^ 
affijiitv in the same general expression. And sucli a co-ordination ist^ 
more vnlunbic, since tlicro has boon a disposition among pkyaiologiata to 
regard tlic introduction of material through the pores of organized textaw 
aa dependent on some iJl-detined ur mysterious principle. 

The phenomena of cndosmosis, first brought to goncr&l notice in the 
EadcMnwU case of liijuid sulistanct's by M. I>utrocliet, may be explain- 
uHtcionDous. ©d OS follows: If some alcohol be placed in a bladder, tk 
neck of which is tightly tied, and the bladder bo sunk in a vessel of 
water, a percolation ensues, eo that the bladder distends to its uttiKSt 
capacity* and might even be burst. Or, which is a Ijottcr method of 
showing the result, if, instead of tying the mouth of the bladder, a gUa& 
tube-, open at both ends, and a foot or two long, be fastened into it with- 
out Icakag^e, as the water introduces itself through the pores of the Uail- 
dcr to mingle with the alcohol, the liquid rises in the gloss tube, ssp- 
posed to be left in a rcrtical position, and, when it has reached tjic top ot 

it, overflows. To c.x]>rcs8 this inward pas- 
sage of the water the tenu cndosmosis w» 
introduee^l, and since a little of the aloc^ 
simnltanoonsly passes outward to mix witli 
the wntiT, it is said to exhibit e-xosmosil. 

In Fig* 40 is represented the cndosmoBi^ 
ter of Outrochot. It consists of a small blad- 
der, a, tightly lied to a tulte, d-, which is open 
at both ends, and bent, as seen in the fignre 
at c; the bladder beuig completely filled with 
alcohol, and the tube to some such point ss 
rf, the arrangement is to be placed in a res- 
sr] of water, e e; almost imme<liatcly the Iwel 
of tlie liquid will be seen to be rising, the 
bend of the tube is reached, and one drop after anotlier falls from tJic open 
end into the glass, b» ^Viid this continues until the Hquids inside and 
outside of the bladder arc uniformly commingled. 

It is to be regretted tluit the terms endosraosis and cxosmosis have 
Tb*** mov*. been accepted by physiological writers, for in tlipse results 
mt-nu An do- tljcrc is iiolhiju' more than wliat we should exi>cct from the 

n<niilt*iiL on ca- , - - T i- -n • mi <• 

iiiiury •ttra<> known prmciplcs ol cnpiJInry attraction. Ihe pores of a 
**""• bladder, or of any other such organic texture, are nothing but 

abort capillary tubes into which water readily finds its way, because it 
can wet tlie substance stirroimding the pore. If the bladder Ijc distended 
with air, and sunk under water, although tlie water will fill the pores, it 



l^i(l»aiiiu«l«. 



A 



FORCE OP ENT)0S1I0TIC WOVEMEST. 



107 



not exude from lliom, and nccumulAtc in the interior of tlic viscua^ 

[>r, as we have seen, a capillajy tiiljc can not cstabliah a continued cur- 

Qt or flow, Bttt the case becomes totally different when the bladder is 

ttUed with alcohol ; for then, as fast as the water presents itself on the in- 

•ncr end of the pore, it is dissolved away by the alcohol, and the necessary 

Icondition for a continuous flow is complied with. Meantime, tlirotigli 

he pore itself a little alcohol passes in tho opposite way by infiltrating 

itfaroagh the incoming water, provided tliat the current be not too strong, 

so endosmosis of the water and exosmosis of the alcohol take place, 

ItUc current of the former greatly preponderating over that of the latter, 

and on accumulation of lir]uid in the interior of the bladder ensues. 

That in all this there is nothing specially dependent on the organic 
lextare employed is obvious from the fact that the same results arise 
when any inorganic porous body is used. Vessels of unglazcd eartlicn- 
warc, pieces of baked slate or stucco, answer tlie purpose very well, ns 

(iaHII also a glass vessel with a minute Assure or crack in it. 
An incorrect representation of the conditions under which endosmosis 
takca place is of\cn made. It is said to depend on tiie relative specific 
grsvity of the liquids. Thus it is stated that the lighter liquid always 
mores toward the denser, more abundantly than tlic denser to the lijrlitcr, 
I The error of tliia is readily shown by many simple iHuatrations. Tims 
water endosmoscs equally well to alcohol, whicli is lighter than it, and to 
gum water or salt water, which are he.tvier. The relation of spcafic 
gravity has uotliiug witatever to do with the action. 
The force with which a Uquid will tlius pass tlirough a pore to mingle 
with another liqnid beyond is very great. I have observed p^r^^ anuMt 
these motions occurring aeainst a pressure of many atmos- "*'^*^** ^^^ 
phercs. And, indeed, m practice we have no means ot mcasur- may toko 
ing its actual intensity; for when a pressure of a certain de- P^'^ 
grec has accumulated, hydraulic leakage takes place backward through 
liie pore, and conceals the true action. 

From tlic jireceding statements respecting capillary attraction and cn- 
^smosis, we may therefore conclude titat, whenever a liquid is in con- 
tact with a porous body the substance of which it can wet, it will freely 
pass into the pores thereof, and, if the necessary conditions for its re- 
moval are present, will percolate or transfuse -with very great mechanical 
power; that this will take place through pores that arc not only invis- 
ible to the eye, but imperceptible by tho aid of the microscope ; that 
some liquids pass thus with more readiness, some with less, some not at 
all — the result in these respects depending on the electro-chemical relu- 
tiona subsisting between them and the solid they arc in contact with, 
and their own force of cohesion; tliat organic membranes present no 
uliahticSf tbcir action arising, not because they arc organic, but be- 




loe 



RELECTINa POWES 



nuini 



eajoo ihcy an porous;' that tbo Bo-cnUod selecting power ia parelv 
y^ fl- physical, as are the aeparaliona and apparent drcomposi- 

tirtns to which it givoa rise. When a drop of colored 
water 19 put npon chalk, tho water sinka in, bnt the color 
ia left on tho Buriace. When weak alcohol is tictl op 
in a bladder, the water will escape tlu^ugh tlio pons, 
and the spirit become anhydrous at last. 

If we take a glass tube, a, a, J^i^, 41, over the lower 
end of which a piece of peritoneum, or other delicate 
membrane, A, ft, is tightly tied, and half fill it with litmiu- 
water, and then place it in a glass of alcohol, e, (?, tho 
level of the liquids inside and outside being adjusted ac- 
cording to their specific gravity, bo that tliere may be no 
hydrostatic pressure either one way or tho other throngh 
tho pores of the peritoneum — as soon as the arrangenwnt 
ia completed, if tho observer be so placed as to vievr itbr 
transmitted light, ho will see tlic water descending fiom 
the pores of the peritoneum in striir and streams throngU 
»»*■ the alcohol in a j)crfcctly colorless state. The menibnuKif 
therefore, has absorbed and transmitted the water, bat has refused to 
the coloring matter a passage. It is to this particular experiment that 
allusion was made when speaking of the non-coloration of the chyle 
when certain coloring material had been mixed with the foo<l. Such 
illustrations may therefore satisfy as tliat the selecting power of organic 
porous textures, like that of inorganic ones, is dependent on simple 
physical circumstances, and for these reasons I exctudo from the mech- 
anism of animal absorption the influence of any vital or otlier mysterious 
principle, and adopt the sentiment of the Abbe Ilauy, tlmt "those ejiccioua 
causes and imaginary powers, to which, in the ^liddle Ages, all natural 
jilienomena, even those of an astronomical kind, were referred, but which, 
throiigli t!ie genius of Xewton and Lnplaw, have been banished from tlie 
celestinl spaces, have taken their last refuge in the recesses of organic 
beings, and from thcso retreats positive philosophy is preparing to expel 
them." 

la view of oil the preceding facts. I therefore regard absorption ty the 
Samm^iT of blood-vesscls as taking place of necessity, because of the po- 
tticniiniTOof rous structure of those tubes; for, though the pores may be 
B loriiuon. ^^^ small to bo discerned even by microscopic aid, they are 
abundantly large enough to i^rmit such a percolation. Whatever ma- 
terial is existing in the chyme in a state of solution in water and also 
soluble in tlie blood, passes through the walls of the vessels, and is moved 
toward the li^-cr, its percolation being greatly facilitated by the onward 
motion of the blood, in which liquid it is dissolved as fast as it presents 




COCRSE OF ABSORBED HATEBIAL. 109 

tsclf. TIic tloublc condition here specified must be complied with ; the 
aatcrial to be introduced must be dissolved in water, am! must be sol- 
ible in the blood. IT the latter condition be wantiug, the vessels seem 
to zaaoifest a selecting power, absorption not taking place, as in the case 
pf litmus, presented above as an illustration — a coloring mnttcr wliiclif 
though soluble in water, is not soluble in alcohol, and so can not, under 
liosc circumstances, pass tlu-oygb a piece of bladder, 

Wijilo thus there is an introduction of digested material from the stom- 
ach and intestine into the blood, the physical principles which are guid- 
ing as in our cscplanation teach us tliat there must be a percolation of 
the more watery portions of tlie blood in the opposite direction — that is, 
into llio digestive cavity. There is every reason to believe that this 
lotntiou is to a far greater amount tlian is generally supposed. Under 
bcrtain circumstances, it is a matter of ordinary observation that the wa- 
ter disciiorgcd from the intestine is moro in quantity than that which has 
>Gcn taken as drink. 

Ttiniing our attention now to the course wliicli is followed by the liq- 
uid which has l)ccn introduced from tiie digestive cavity „ , . 
[nio tbo blood-vcsscls, wc must bear in mind that the con- ibwrb«<int*ie- 
lent of those vessels is composed of two dislinct jiorlions, JJ*. !°Jii^cm- 
^c umtlcT tlms recently introduced, and tho original venous *>on!i ii uuder- 
These together make thcur way through tiie portal ^^*' 
the liver, a gland of double function, and, as we may Siiy in tliis 
of double structure; for, though it has a duct tor the disposal 
if tiie products which arise from its action on one portion of the material 
us brought to it, the venous blood, it is ductless as reganls the other 
rtion, which has been received from the digestive cavity. This jwrtion, 
oodrr the infiuenoe of the cell structure of the liver, undergoes profound 
modification ; for instance, liver-sugar makes its appearance, though none 
existed before. It is not necessary for as to specify these changes par- 
ti fi i Uri y here, since wc shall have to ej^aminc tliem more in detail in a 
sabaeipient cliaptcr; but it may be obscned that tlic anatomical jic- 
coUarity of tlie Uver in this branch of its duty is, that it simply impresses 
a cKange on the compounds tiius brought to it, gives rise to no excretions, 
and therefore lias no channel or duct of escape, unless indeed we say, as 
we ore actually jaslitie<l in doing, that tho hepatic veins themselves aro 
the ducts of tlie Hvcr in this rei<pcct. 

Though it does not strictly appertain to llie subject of which we are 
now speaking, absorjition, we may, for the sake of complctciicss, describe, 
in a superficial manner, what occurs to the other constitmuit of the porlid 
blood, it« proper venous portion. This, brought into tho liver, is acted 
ujion by that organ and decomposed into two portiuns, one of which, con- 
stiluiiiig the bile, is brought back eventually through tho proper bile duct 



110 



8l"SDURT OP AnSOBPTIOS. 



into the intcstixKN Tltc otber is carried into titc blood circulation. I be- 
lieve tliat this separation is of a purely ph}*aical kind, and is aocomplisln 
ct\ by mere iHtxation, the dements of the bile all pre-existing in the Wo 
rionever that may Ijc* the separation in a chemical sense is vcr>' dia 
for the Ditrogcoi^ed ingredients are saved to the system, and carried inlo 
the general circulation tJin>ugIi the bc]Kitic veins ; but the biliary inatc- 
Hetiirn itf » '^"'^ brought back into the intestine is a hydrocwlton tinctiiwl 
pan le Un with a little coloring matter, which, being on a rapid career of 
**"** * rctroprado mctamorjihosis, ia prono to act as a fennont, ud 
therefore ujifit to remain in the system ; accordingly, it ia removo<l with 
the excrement. The other portion, the hydrocarlxtn, whicli baa 
bronglit into the intestine, is not yet done with ; advaiitagtHUis use can" 
still Ix* niadn of it. It can aid tn the intnxluction of fnt.s llirough tin 
villi into tlic tactrals, and, from its comlnistible nature, is of an equal valne 
to the system Tunth the oils it tlius helps to introduce. Wc may ndvnn- 
tagcously trace tlic course whicli it follows, for in so doing we shall com- 
plete our description of the function of absorption in its most geneni 
sense. 

The fat matters which have been subdivided inlo portions of mimv 
ManticTof scopical minutcness, small globules, each of which is coatcil 
■ciiooof over with a dcHcate film of albumen, and all brought therefore 
* ^ into the state of an emulsion, can make their way by reason of 
the peculiar properties of the investiture which thus covers them through 
tlic pores of the villi into the lacteaL For my own part, I do not believe 
that tlicre is any passage through the epithelial colls, but that it ia en- 
tirely interstitial, and that it is not unlikely that the hiliary constitnent 
aids in this progress. It signifies nothing that the spaces through which 
the fat globules have to go are less than their own dismetcr; they can 
elongate into worm-like forms, just as, under tlic SHmc circumstances, 
bloocl-ccUs can do, and, the moment they reach the cavity of the lacteal, 
rcassumc their sphericity by reason of their crtheaion. The albumen 
that now accompanies them in llic liquid form, us the other chief ingre- 
dient of the chyle, comes, for the most part, from the bloo<M*cssel9 of 
the villi. The chyle moves onward to tho mesenteric glanda, and makes 
its passage through them cither in naked tubes or through their pulpy 
structure, is submitted to celt action and to arterial blood, undergoes the 
morphological clianges which Iiave been described in tlie preceding chap- 
ter, and, gaining the thoracic duct, ia brought into tlio general circula- 
tion. 

In the description licrc offered of the function of absorption, the agen^ 
cy of pliysicftl forces alone has been considered, and these I conceive to 
be abundantly sufiicient to enable us to account for nil the phenomena. 




THE BLOOD. 



Ill 



CHAPTER Vn. 



I 



OF THE BLOOD. 

TV QiJEou tmd Rthtion q/" Bfiml in the Systfm.— The Pltvana and OHn.—Cmeral Propfrties 
ibkI C^mjtotiiim of the lilood.- — (.^Minttl^ in the Bodi/. — Coa^tntion. — Itlood-rtJU. — ■Their tuc- 
eeaweeFoHM. — Theper/ttt Celt — Htntatim iU Propertia. — Sumlrrr of Biond'TrUM. — IHas- 
mn: ita Chmfioatitm, ami yanatioit 5/' itM IwjrtdienU. — .4 fluiwM, Fibrin, Fat, Sm/ar. — J/w- 
erat fntftftKcntx t^the Ctllx (fut Plaxmo mrnjiurrti. — (iatfs of the. BkufL — Cfumrjrx ocrtirriiiff 
timnag the Cimihtion. — (JcHtral FtutctioM <{f the tUffrrtat Intjrtditntg oftheBiood. — ItttrodtK- 
«w» q/* Osyjai b>f the (XtU. — Thdr tratattut Duration. 

It is necessary for the functional activity of every organized Leiug that 
ihcrc Kimll circulate through all {larta of it a nutritive iiqiiicL In plants, 
it is the sap; in nnimals, llic lilootl. 

Since the life of plants mnnifesta itself, for the most part, in a purely 
formative result, and involves little or no destruction of parts, ti,« i,1o«I: its 
the circulating current ia tievotcd almost entirely to nutrition, fu'iciion*. 
iJut in animals, whose conditions of existence involve extensive and un- 
ceasing ilcstnietion, the current U burdened with another duty. It is 
also the means of removal of ilying or wasted portions. 

In the first chapter it was shouTi that about a ton and a half of mate- 
rial is required by a man in the course of a year, and that In introdadion 
tlie ifmne jjeriod a like amount is removed from the system. m„'l"™i7,v'(he 
When we reflect that the introduction and removal of this tlooii. 
immense mass is accomplished through the agency of the circulating 
blood, it is ob^ns that tliat lluid must be undergoing the most rapid 
changes. The rapidity with wliich dying matters arc removed is strik- 
ingly illustrated by the niinuie extent to which they are permitted to ae- 
cnmnlate in a hcidtliy state. These elements of decay are strained off 
or exhaled as quickly as they arise. That fancied power, the *" vis med- 
icatrix natural, " is only an ideal exiiressJon of tlie perfection witli whicli 
the various elimuiating mechanisms work. Poisonous agents, whether 
they Ilivc been introduced from without or have originated from morbid 
actions within, like all other useless or noxious products, find their prop- 
er channel of escape, and the system will thus rid itself of intoxicating 
liquids and narcotic drugs if their quantity does not exceed tlie amount 
that it can destroy or excrete in a special jxjriod of time. 

Considered in its relation to nutrition, the circulating liquid presents 
many interesting aspects. Eacli of the thousand variously-constituted 
ports of the body is withdrawing the supplies it needs: the muscular, tho 



113 PBOPEBTIES OF THE BLOODw 

interconncc- nervoos, the cartilaginoQS, the bony ; and hence there arises 
thro^'^h'thu^ ^ general balance in the system, each part *n«t^iTig its demand 
ctrcuiatioD. at a Certain rate, and each observing a complementary »> 
tion to all the rest. Many of those phenomena which, in the infanc)' of 
physiology, were r^arded as instances of sympathy between difTerent 
ports, arc clearly dependent on these conditions ; for the development of 
one part, by abstracting special material from the circolating liquid, po^ 
mits the co-ordinate development of another, or perhaps puts a stop to 
it. The minutest portion of the mechanism is thus indissolably coo* 
ncctcd with all the rest through the medium of the blood. 

Seen as it circulates in the vessels, the blood consists of a colorless 
Tbe plumft ^^tud Containing corpuscles. In man, some of these corpuscles 
and cells, are white and others red. To the liquid in which they float, 
the designation of the plasma is given ; the colored corpuscles, &om tiieir 
Properties of shape, are called discs or cells. Tbe specific gravi^ of the 
the blood. blood varies from 1.050 to 1.059, the variation being, to a con- 
siderable extent, duo to variations in the quantity of the cells. The 
temperature is about 100° Fahr., the reaction always alkaline ; there is 
also a faint sickly odor, which differs in different animals. The capacity 
of blood for heat is in direct proportion to its density. The cells give to 
the blood its tint of color, and this, in the systemic arteries, is crimson, in 
tlie veins, deep blue. However, the color of arterial blood depends con- 
siderably on tlic condition of respiration. An imperfect introduction of 
oxygen, as in hot climates, causes the arterial blood to assume a dark coIot, 
and the same is observed when chloroform, ether, or diluted irrespirable 
gases arc breathed. The blood of the male sex is heavier than that <^ 
the female. 

Constitution of the Bhod. 

Water 784.00 

Alborocn 70.00 

Fibrin 2.20 

(Globulin 12S.60 

^"^ iHffimatin 7.C0 

/ Choleslcrine 0.08 

I Cerebrine 0.40 

J Serolino 0.02 

I Oleic and margaric acid ^ 

Volatile and odorous fatty acid > 0.80 

. Fat containing phosphorua y 

fCblorido of sodium 8.C0 

Chloride of potassium 0.S6 

Triba^ic phosphate of soda 0.20 

Carbonate of soda...., 0.84 

Sulphate of soda 0.28 

Phosphates of lime and maf^esia 0.25 

.Oxide and phosphate of iron 0.50 

Extract, salivary matter, urea, biliary coloring > _ . _ 

matter, accidental substances \ 

1000.00 



Fats 



Salts 



113 



£lnaeMtaT]f Cofnj>ontioM <^ drml 0-t lUood. 

Carbon DIO.SO 

Ilytlrn^n Tl.TO 

Kiinipi^n Ifi0.70 

Oxygen t... 218.00 

ABlum ■ 4<.20 

1UUU.U0 

lis tabic leads to the liypollictica] formula of the uJtimate constitu- 
ioii of blood I 

As to the quantity of Unod in tlic circulation, it has been variously cs- 
inuted. It may perhaps be taken at one eighth of the weight Qy„ntj,_pj 
f the body, a number which is agreed upon by several authors* biowi in tbe 

id in support of which Lehmaim mentions tho following in- ^' 

resting observation : '* ily friend, K. \\'ebcr, determined, with my co- 
pcratioD, the wciglits of two criminaLs before and after decapitation. The 
Bnntity of blood which escaped from the body was determined in tho 
kllowing manner : "Water was injected into the vessels of tlic trunk and 
ead until the fluid escaping from tho veins had only a jxilc red or ycl- 
Dw color. The quantity of blood rcmaimng in the body was then calca- 
Medby instituting a com]Miri.«on between tlicsolidrcsidncof this pale red 
qocous fluid and tliat of the blood wliich first escaped. By way of illus- 
ntion, I subjoin the results yielded by one of the exjreriments. The living 
©dyofoneof the criminal? wciglicd ti0,140 grammes; and the same body, 
^a the decapitation, 54,000 grammes; coiiseqiicntly, 0540 grammes of 
^^H bad escaped. 28.500 grammes of this blood yielded 5.3G grammes 
Rolid residue; 60.5 grammes of sanguineous water collected after the 
BJectiou contained 3.724 gratumes of solid substances. 6050 grammes 
f the sanguineous water that returned from tbe veins were collected, and 
facse contained 37.24 grammes of solid residue, wliich corrcsiionds to 
980 grammes of blood; consequently, the body contained 7520 grammes 
(f blood (5540 escaping in tlie act of decapitation, and 1980 remaining in 
he body); hence tbe weight of the whole blood was to that of the body 
■early in the ratio of one to eight. The other experiment ^-ieldcd a pre- 
iiBcly similar result," 

A short time after it has been drawn, the blood undergoes coagulation, 
ititl is then said to be composed of the serum and the clot. Sponijuwoa* 
n ibia state it ia sometimc-s sjwken of as dead. Tbe phiania i!I,','„'^J^ 
if lining blood difiers from the .scrum of dead in containing doi. 
ibrin. 

The coagnlation of the blood commences within abont ten minutes 
ifter it has been drau-n, and the clot undergoes a subsequent th* cnajfui*. 
iring one or two days. To understand the »'«'»' blooJ. 
nature of this singtilar change, we may conveniently regard the 
H 



once 



COAGULATION OF THE BLOOD. 

liTUig blood as containing tlircc leading constituents — on aI\niniinoiu li^ 
uid, tibrin dissolved therein, and the cells. The coagulation ari«ea (rom 
the tendency of the fibrin jMirticIcs to agglutinate together. As tbis takes 
place, the colls arc caught in the meshes of tlic network that arisea, anj 
a voluminous rod clot is the result. So the serum of dead blood oon- 
tains no fibrin, and ditfcrs from tlic plasma of bving blood iu that impor- 
tant particular. 

It has been observed that exposure to cold retards coagulation, as docs 
likewise tlic absence of air, or covering tlic blood over with a Kim of ol 
The condition of rest promotes it, as also docs the presence of rough or 
angular bodies. Blood will yield up its fibrin readily when stirred with 
The bufl> n stick. When, for any reason, the cells sink more rapidly ihsa 
vmL usual from the surface of the blood, the tibrin of the supcnutant 
portion coagulates alone, giving rise to a stratum free from tlic red color, 
and dcsignatcil the buffy coat, and on tlie suWcquent contraction, since 
there are no cells to hinder tho librin, its parts upon this stratum 
drawn more closely together, and the clot becomes cupped. 

By those who accept tigurativc expressions as an explanation of ph; 
ExpltoBtionor iological facts, tJic coagulation of the blood is said to be d 
«»*iE»J«tioo. |(j j(g death ; some, however, have regarded it as an abortive 
attempt at organization, and therefore a manifestation of Ufo. Such con* 
tradictory explanations lose much of their interest when we examine the 
facts of the case critically. I believe that nothing more tikes place ia 
blood which has been drawn into a cup than would have taken place had 
it remained in the body. In either case the fibrin would have equally 
coagulated. The entrapping of the cells is a mere accident. The hourly 
demand for fibrin amounts to 62 grains ; a simple arithmetical calcnlati<m 
will show that the entire moss of the blood would be exhausted of all 
the fibrin it contains in about four hours, so that the solidification of 
fibrin must be taking place at just as rapid a rate in the system as after 
it hag been withdraw^l. No clot forma in the blood-vcascls, because the 
fibrin is picked out by ttic muscular tissues for their nourishment as fast 
88 it is presented, nor would any clot form in a cup if we could by any 
means remove the fibrin gramdcs as fast as tlicy solidified. JM 

That blood-fibrin ditfers from muscle-fibrin in certain reajiects is 1o b^fl 
admitted, but it does not follow that blood-fibrin is in a condition of ret- 
rograde metamorpliosis. It may reijuire modification before it can be 
received as tlie syntonin of muscles, but that such a conversion actualh^^ 
takes place I tliink there can be no doubt. ^| 

In entering oti a detailed examination of the constitution and func- 
tions of the blood, our attention will have to be directed, in the first 
place, to the ocUs. It is sufficient to arrest our thoughts at once when 
wo learn that for eveiy beat of the pulse nearly twenty millions of these 





srccEssivE roTDis ov blood-cells. 



tis 



organuma die ! Physiology has ita possiug wonders r.s well as astron- 
omy. 

In the lil'e of man there are (hrcc periods distinguished firom each other 
hy the nntore or structure of the blood-cells. Those of the g 
first period originate sunultaneoiiHly with, or even previously nns of l^tood. 
to, the heart. These are sometimes desi^ated as emhrj'O 
cells,-aiid in that view bear the same relalion to tliosc of the second pe- 
riod as lio tlie I^Tnph coquisclcs to those of the third. They are color- 
less and spherical cells, containing granules of fatty material, and having 
a central rmclcus. These are developed, by a process of internal deli- 
qnnsopnce, into cells of the second period, which have actpiired a red col- 
OT, and in o\*ipnrou3 vertebrates an elliptical form, though in man they 
•re cinmlar. They are flat or disc-like in shape, liavc a diameter of 
about I j^n of an inch, with a central nnclens of half that size. Somc- 
\xaxA they appear to undergo multiplication by division of the nucleus. 

These cells of tlic second period are replaced by those of the third, the 
L|mi?ition being clearly connected with the production of lymph and chyle 
'tttpQsclea. By the end of the second month of fcctal existence the re- 
placement is complete, and the class of cells or discs that has now arisen 
is continued during life. The mode of their production, according to Mr. 
Paget, is this. The chyle or lymph corpuscle loses ita granular aspect, 
and acquires a pale rcl color, which gradually deepens ; the corpuscle be- 
comes smooth, loses its spherical form, and, condensing, takes on a con- 
vex lenticular shape, and eventually a bi-concave. While this change 
of structure is going on, the s{)ccific gra^nty increases tlirough the con- 
densation, and the development closes by the spherical, white, granular, 

aph corpuscle becoming a red, bi-concavc,non-nuclcatod, circular, small, 
heavy blood disc. 

The cell of the first jvriod is therefore spherical, white, and nucleated ; 
that of the second, red, disc-shaped, and nucleated ; that of tlie third, red, 
disc-shaped, bi-concavc, and non-nnclealed. 

The primordial cell advances in development to different points in dif- 
9t orders of living beings. The blood of invertcbratcd DevefeiimeDt 
nals contains coarse granule celli*, which pass forward to J^^h^^^^ij 
the condition of the fine granule cells, and reach the utmost Kriea. 
perfection tliey are there to attain in the colorless nucloatpd ceJl of the 
fii»t period of nmn. In oinparous vertebrated animals tlie deveJopmertt 
i« carried a step farther, the red nucleated cell arising, and in them it 
stop^ at this, the second jteriud. In niammals (he third stage is reached 
in the red, non-iuiclealed disc, which is therefore the most perfect form. 

This perfect form of blood cell, as it occurs in man, may be described 
as presenting a tiatteiied shape ; the bright spot, which is sometimes seen 
in tlu» ec-nlre. arising from a refraction of light due to the form of tho 



116 



CnOCUUl AND ELUmC CELLS. 



disc and not to & nucleus. The sac of eacli disc is eksttc, so that it c&n 
rroMrrtioi and ^ swollcu l>_v watcT UfltU it bccomes coHvex OF cvch globu- 
►Ue or Uo jwr- lar, or hy immersion in thick airup may be made to sbriiik, 
effects arising ^m tlie endosmotic infiltration or cxndatioD 
through ita wall. When passing through tlie 6nc capillaries in the 
cour»c of tho circulation, the cell, by reason of tins claaticitVt can miLc 
it^ way through very difficult passages, extending itself into a cylindroid 
form, or by bending, but it recovers its original sha^tc as soon as relieved 
irom pressure The average diameter of the cell is estimated at ^^Vc ^ 



FU}. • 



% • 



© 



« 



Uiuawi bloMl-«clto HMgtU«l 900 dUm* 



at a a, chyle corpuscles. 



an inch, the c:&tremcs b»ng y;^> and -jt^ 
The thickjiess of llic cell is about i^^-^ (if 
an inch. The cell owes its color to hffnia- 
tin, wliich exists in its interior in a state of 
solution, and associateil witli globulin. 

The facts mentioned in the preceding par- 
agraph arc illustrated by the annexed en- 
graved photograplis. ^ig. 42 represents hu- 
man blood-ccUs. Their form is circular: they 
hare a central depression, but no naclens. 

J'^ig. 43 represents the elliptic nucleated 
blood-cells of the frog, with here and ther&i 
J'^iQ. 44 represents the cndosmotic action of 



# 




EUlptle Uood-cella of ft«s BiRiiUad fMdkB»> 

tern 



Aetloo of T»ter OB illpue KlU 



water on these cells. Fuj. 45, the action of acetic acid in darkening or 
concentrating the nuclcns. In Fig. 40 wo have an illustration of the 
size and appearance of the blood-cell in a reptile, the photograph from 
which this figure Has taken luivliig been niado under tho same magni- 
fying power OS that employed in obtaining the photograph of haman 
Uood. 



FORMS OP Bt.OOIVCELI.9. 



[17 



i%», ^^ 



FfO.». 





ArOoa of wxtie add on vlUpUc ccllft 



Rfptile b^ood-eclls Diai^iiiAod (MM diimrten. 



I 



The maiinnals In which tlie hlocxl cor|iuRdes are not round, but cLUp- 
ttc and bi-convcx, arc the conicl, tlic dromednr}^, and tho llama. In 
birds and amphibia they arc ovah The difference in the shape and size 
of these celU 19 of the more importance, since observations and mcasure- 
loents by the microscope may lead ua to a correct reference of a sample 
of blood to ita ori^ii whcu chemical analysis would aftbrd us no assii^t- 
wice. It is not to Iw forj^otten, however, tJiat botli in size and form a 
blood-ceil undergoes changes according to unequxd pressures y - .r , 
cierled hikiii it, or to the physical circumsf imces imdcr which ibe fomt of 
il is placed, liquid readily finding its way into its interior or *' 

cswUng therefrom according to the lawa of endosmosLs, the elastic sao 
perfectly accommodating itself to these changes. As a consequence of 
these modifications, there will, ofcourse, follow variations of s|>ccific grav- 
ity in the cell, tUffercnces in its tendency to sink in tlie plasma which 
unds it, and also differences in its tint of color. 
"^y Mr. Wiiarton Jones, the colored blood-disc of the mammalian is 
rcgxrded as bebig homologous with the nucleus of the color- .. .j^ 
leu corpuscle of the same blood, and it may therefore be tiiMc i> a cviiw- 
spokcn of as a free cellwform nucleus, the cell itself having '""" ""*^*'**- 
deliquesced or become disintegrated, and the nucleus, filled with globulin 
and coloring matter, remaining. 

The cdl wall of the Llood-cclls is generally admitted to be fibrin, or 
KMDe substance allied thereto ; but there has been much dif- v.m«,of ij.- 

Ifcrencc of opinion respecting the constitution of the nucleus wii walliuid 
of those cells whicli possess it. By some, this also has been " *"*■ 
re^rded ^ fibrin ; by others, as fat ; and by others, as a species of horn, 
to which the designation of nneleine has been given. 
The cell wall of the while corjmsclcs does not appear to be elastic 
It is visdd, and hence these bodies tend to agglutinate with one another : 



118 



coMPoemoN or hlooexells. 



Soorco of iron. 



in aspect it is granular. The contents appear to be an albaminoos sen 
lution. in which fine granules are euftpended. 

Though 1VC have described the mesenteric glands as tJic original place 
of fumiation of the Uood-ocUs, it is to bo nndcr^itood thai 
theao become perfected in ibc drculation of the blood ; and 
from what ivill be said respecting the function of the li^'er, it may lie in- 
ferred that that gland is the scat of a most important change : therr 
probably they receive their iron. That no special organ is cxc1u«vcIt 
charged with the duty of forming them appears from thia, that the first 
form of blood-celU arises in the genniual &rva of the embryo when there 
is, as yet, no ghind. 

Otmpomiiim ^Bhod-eeUt. 

TVntcr C89.00 

HcmBtia (iiictudiug inm) 16.7fi 

Olobulia aodccU mcmbnao « 28S.23 

Tat J.ai 

ExtncUre S.00 

Uiaent nUtiuioQe »,» 8.18 

lOUO.OO 

Leaving (ho water out of consideration, the predominating inj^redients 
of blood-coUs arc therefore globulin and hivniatiiL. The former is a sub- 
gtance approaching, in properties, to casein, or pcrhajw intermediate be- 
tuecu casein and albumen. Its constituents, as determinod by an olti- 
matc analysis, are the same as in the case of tliose bodies. 

Ilamtatin is distinguished by its rod color. When isolated, it e^ibits 
Ounirea ofwii- ^^^ cliangcs of tint characteristic of ortcrialiKation in a doubt- 
er dapcnding fij manner. There arc, however, many facta which lead to 
ibc^oimorti)« *he supposition that the color of arterial and venous blood 
cell*- docs not depend so much on a chemical cliango in the hccina* 

tin as on an alteration of tlic figure of the discs. ^_ 

The constitution of hfematin is C\^, lU,, N,, O^, Fe. It exists tuii^H 
Propertietof *^*o foHus, soiublo and coagulated. It has hitherto been stnd- 1 
^■***"***^ icd only in the latter state, and is soluble in weak alcohol 1 
acidulated with sulphuric or hydrocldoric acid, but not in water. Its , 
solution is therefore precipitated by tlie addition of tliat liquid. In weak 
solutions of alkalies it re.itbly di.^solves. Formerly its characteristic red 
color was attributed to the iron it contains, but that metal may l>e en- 
tirely removed from it without changing its tint. The amount of iron it 
yields is alx)ut seven per cent. 

Ila-matin occurs in tlic blood-cells associated with globulin, and would 
seem to owe itij origin to the action of the wall of the cell, i£ it be true 
that the red cells originate from the white ones. In this formation of 
Jiieroatin tliero are several reasons which lead us to infer that fat takes 
An essential share. 



A 




COMPOSmOW OP n-EMATIN. 119 

Vitimttte AnafgxU qflltrmurin. 

Cftiboo (mSAJ 

llydrofren 64.4A 

Nitniften 103.00 

Ox>-gea 118.61 

Inm <iQ.3 l 

lUOO.OO 

The rcmarkalilc feature m tlie composition of Oils body is the large 
quantity of iron it contains. The percentage amount of this i,oa in Uie 
metal in the blood of the foetus is much greater than in that of '=*^*'* 
the mother. After birth the proportion declines, but it rises again at 
puberty. These variations in the amount of the iron arc, however, de- 
pendent on coTTcsponding variations in the amount of cells. 

The importance of the remark, when we arrive at the study of the 
Inlet justifies ns in repeating tlmt the iron of the blood 1x>Iongs to the 
luBmatin of tlio cells, its percentage proportion varying with tlieir condi- 
tiofit and also with the region of the circulation from which they liavc 
been drawn. As derived from different animals, the cells present dilfcr- 
cnt quantities of this metal. Thus Schmidt found in 100 parts of dry 
^>lood-cclU in man, 0.434b ; in the ox, 0.609 ; in the pig, 0.448 ; and in 
the hen. 0.B20. 

The ci>'staUino substance of blood occurs under three different forms, 
in prism.s, tctrahedra, and hexagonal tablets. In the pris- „ ... 
ttutic form it is derived from human blood, that of fishes, nuuuoooof 
^nd of some mammals; in the tctralicdral form it is obtained 



Pi". «r. 



ME***. 




Uunan lwMnk^.]auU, 



no(>d.«ri>-aUb of Gulun-plf. 



5oni Guinca-pig«, rats, and mice ; in the hexagonal fonn, from squir^ 
tU. Blo*)d-crT8tal3 are of a red color, ^-ithout smell or taste, losing 
licir water of crystallization under exposure to the air, the different forms 

prracntiiJg diiTcrcnt rates of solubility ; the tetrahedral being soluble 




biuinl'CryMiLk of H|ulml. 



in 600 parts of water, the prismatic 
in 90 parta only; t!ie solution in 
llic fonncr cas« being pinkiab, that 
of the latter, <lark rwL Thcr are 
also dissolved bv Rcctic acid, the nd 
prussinte of potash prwhicinp a pre- 
cipitate therefrom, as in tlic case of 
otlicr protein bodies. Ctiloriue de- 
colorizes their solutions wi'l erives a 
wliitc tUky precipitate. The ervi- 
tnls, irlicn hentcd, swell, yield sn 
odor like burnt horn, and. afti^ com* 
bustion, leave a small quantity of 
ash. Kroni the difficulty of obtain- 
ing blood-crj'stals in a state of purity, their constitution is not known 
with absolnte certainty. The ash which they yield consists of about 72 
\KX cent, of oxide of iron, and 21 per cent, of phosphoric acid, the protein 
constituent being apparently identical with otlier protein bodies. Tbe 
Moda of nh- CO*®^^** "*'*?' ^ obtained for examination by covering a mi- 
uiolnguiooJ. nute drop of blooti with a gift»a slide, and, after adding water, 
"^ alcohol, or ether, to permit a gradual evaporation to ensue 

The amount thus producetl dqjonda very much upon the jiresenco of light; 
thus Ix>.hniann found that while he could only obtain two per rent. <^ 
cr^'stala troni the blood of the Guinea-pig in tlie dark, he eould obtain 
more than acvcn per cent, in the sunlight. 

Leliinjiiin Ix'lieves tfiat the crystalline substance is not a mixture of a 
pigment and a protein body, but a pure chemical compound, Luvutg cither 
a ftjilt-like or conjugated coiL^titulion. 

The color of the blood, as dependent upon the tint of its cells, is, ac- 
Culor of blomu cording to the views of llenle, connected to a considerable 
*^nd "m Uitir *^*^&'"^ ^'^^ *''^ **^''"* ^^ tliosc organisnis as they van* from a 
fonn, concave to a convex surface, and not with the sluto of the 

lucmatin. Wlien they are more concave they are of a crimson, when 
of a more convex, of a darker hue. Moreover, during these variations 
tiieir investing membrane must necessarily change in tliickncss, and this 
likewise must alter their mode of transmitting light. 

Among llic causes which can impress a change on (he figure of the 
blood-cclls ought particularly to bo specified exposure to oxygen and 
carbonic acid respcclivcly, the latter causing them to become more opaque 
in their centre, broader upon their edge, the cell distending; an opposite 
effect ensuing under exposure to the former. In the case of the blood- 
cells of frogs exposed to oxygen, the long and short diameters both di- 
minish, and the wall becomes granular; otter exposure to carbonic add 
they increase, the wall becoming jx'llucid. 




KOIBEH OP DLOOD-CELLS. 

Constitulctl thns of an cla.stic sac fillwl with globulin and htrmaiin, the 
KcclU float in tlic plasma. Tlicy are nourished at its expense, ami when 
Hie, deliver up their contents by deliquescence to xt. Accouipany- 
tbem are the white corpuscles, from which new generations are to 
It is usually stated, timt for evci^'' .'50 reil discs there tJip whlio 
I u one white corpuscle. They may be readily discoAcrcd dor- "'T'»<;'«»' 
I iag tiic circulation by the microsoopts many of them occupyiiig the cjcte- 
rior of the current, as though iht'y had a special relation to the soft tis- 
sues. It may perltaps be erroneous to regard these large white corpns- 
■clca as the embryos of tlie red discs. Ticasona could bo assigned in sup- 
port of tlic doctrine that the same primitive germ going onward to devel- 
opment may, at a certain point, diverge in two directions ; it* it pusses 
■ through one, it will pexfoct itself as a white cell ; if through the other, as a 
I red disc. 

m The proportional number of blood corpuscles in different animals vsr 
Kncfl considerably. Generally cold-bloo*l(?d mammals present Kuinb«ror«eiu 
fewer than warm-blooded ones, birds having more than quad- ,i"f|i,,^n't'^'' 
.npeds, and among these the camivora more than the herbiv- mub. 

Of different domestic animals, the jiig, the dog, the ox, the horse, 
cat* the sheep, tlio goat, poss(*ss them in the ordrr in which their 
hare been mentioned, the goat having only 8G to 145 in the pig. 
|Thcir proportional number also varies in ditl'ercnt regions of the circula- 
tion ; thus it is said tliat arterial blood contains fewer than venous, the 
ortal blood fewer tlian the juguUr, the hepatic more than the portal It 
not, however, to l»c overlooked, that in all these determinations the 
fltity of water which cliances to be present controls tho cstiuiatcs, and 
ftt tltercfore, as tlma offered, they are really of less interest than might 
at first eight Ijo supposed. 

We have next to speak of the plasma. It may l>e described as a dear 
litly yellowish colored fluid, consisting, as all animal ComposiUoii 
9, for the most part of water, holding in suspension or fi'i'l""*. 
olulion albumen, fibrin, fats, and various mineral bodies, as the foUow- 
: analysis shows. 

Proximate C^mpontion (/Ok Plama. 

Water »03.90 

AJbamen. TH.W 

Fibrin ., 4.05 

Fat - 1.72 

Extractln „ 8.W 

MiiMMl ■abeUncoj BM* 

liMlU.OU 

Of the watw it may be remarked, tImt tlio usual percent- \viitor<>fih« 
stimate made of its quantity, as regards the entire blood, wiioi.> i.UK>d: 
om 700 to 790 parts in 1000. Within these limits it is '" ^■•^^'«* 



122 ViJlUTIONS IX WATEB, JLLBUMEX, AND nSBlX. 

liable to rapid variations, as dependent on tlio condition of tliirst or tlie 
recent indulgence iu dnnkB. It docs not increase in proportion to the 
amount which has been imbibed, fur the Malpigltion bodies of t-he kidfier, 
na will hereafter apjKyir, strain it oft' with great rapidity. WTiea the 
bloo<l-ve38el3 arc distended 1o a certain degree^ they reftiBc an entrance to 
it. The necessity of these provisions arises trom the fact tlmt there ii a 
(xrtain state of viscidity which the blood must possess for its proper cir- 
culation. 

Bes]>octing variations in tlio amount of water in the blood, it may be 
stated that that of women contitins more water than tlmt of men. Ama^ 
dilTerent animals, the serum of tlic amphibia contains tlic largest quantity; 
and among mammals, that of the hcrbivora more than that of the caz* 
nivora. Obtainwl from different vessels, the arterial has more than 
venous blood, but the serum of the portal vein contains more than that 
of any other vein, tho proportion depending on (be amount and time of 
the ingestion of water. 

The albumen varies in quantity from GO to 70 in 1000, It is prob- 
TarlftUoiu In ^^^^ associated or combined with soda. It exists in the 
qmniity of k1- blood of Uic Splenic and hepatic veins as the neutral albunii- 
'*'"''"' natc of soda. It docs not appear to contain any pliospboros, 

OS was at one time supposed. It is tho plastic material from which aU 
the soft tissues are nourished, and by it tho cells themselves grov. 
Fibrin arises from it in tho blood in the same manner as it docs during 
the incubation of an egg; every caro is taken to economize it in the sys- 
tem, and it is never excrettxl except in disease. 

Tiic quantity of albumen is greater in venous than in arterial blood, 
the proportion increasing during digestion. It also prescnta variations 
in different states of disease. Its comlition varies in various ports of the 
circulation^ a circrunstancc, to a considemblc extent, due to the nature of 
the salts, or to the quantities of alkali with which it is associated. 

The fibrin is usually estimated at 2 or 3 parts in 1000 of blood. It 

TariiUonn In ^^y ^"^^ ^ ^^^ *^ ^ ' **^ "^ ®® ^^^^ *^ ^i* There IS a con- 
iho<iii*n<i<yar stant drain upon it for the nutrition of tho muscular titiisucs; 
' and since it ori^nates in the action of oxygen upon albu- 

men, we should expect, as is really tho case, that arterial blood would be 
richer in it than venous. The portal blood contains it in mlninuim quan- 
tity. Its percentage rises if oxygen be inhaled, or the respiralorj' pro- 
cess be quickened; for similar reasons, it uniformly increases in acute 
intlamniations. The ultimate analyses of fibrin seem to show that it con- 
tains more oxj'gcn tlian albumen, and this corresponds with its mode of 
origin. It is an important practical obscn'ation, tliat though it is easy 
to regulate the quantity of cells by variations of diet, tho amount of 
fibrin con not so readily be clianged in that manner, nor its dc^'dopmcnt 



J 




FIBRIN, PAT, AlTD SCO Alt OF BLOOD. 123 



chocked by venesection. Tlicre is lesa tibrin in llie blood of the caraiv- 
ora than in that of tlie herbivora. 

It lias been asserted, as was mentioned before, that tlicre is so wide a 
difiurence between the fibrin of blood and nmseular fibre, nttrin ii « hi»* 
that we con no longer regard the latter as arising from the lo^'viicUc iw.i/. 
former, but must consider it merely as coagulated albumen ; and that, 
flince the action of acetic acid upon it shows its relation to gelatine, it is 
probably more nearly related to the tibro-gelatinoua tlian to the cellulo- 
albuminous tissues. Hut, although the fact that fibrin contains more 
oxygen tlian albumen seems to lend weight to such views, since oxida- 
tion appertains to tiic retrograde rather than to the a.sceiiding metamor- 
phosis, there arc so many arguments in favor of the oUl doctrine, tliat 
I think it may be regarded as tlius &r unshaken. Moreover, it is now 
esUbluhed beyond any doubt, that by nitrate of potasli, and other salts, 
£fann Toaiy be transmuted into a substance analogous to albumen. 

The fats vary very much in quantity at different times. The amount 
is usually stated at from 1.4 to 3.3 in 1000 of blood. After a meal the 
plasma may be actually milky, tlirougli the fat globules Y^jji(,n, („ 
brought in by the chyle. We have already shown that tbo quantity of 
starth will give origin to fat, and oily substances can be ob- 
tained from lactic acid itsell'. The iiitrogenized bodies, during their de- 
atmction, likcavigc yield them, and it is a normal function of the hvcr to 
effect th<\ pro<luction of fat. 

The scrum contains only an insignificant quantity of free fat ; but 
there is a large proportion of Ba)}onified fat in it, as well as the lipoids 
cholcstcrinc and aerolin. 

The view heretofore taken, tliat this class of substances is not histo- 
tie, but only respiratory, requires to be modified. There UM!iiofUi«fiiu 
in to believe that tlie blood-cells tlkemaelves can not *^ '****''■ 
1)0 fomed except in presence of oil, which is also necessary to enable ni- 
trogentacd bo<liea to assume the ferment action. The nuclei of cells con- 
tain fatSi, as do also embr^'onic structures generally. Cholcsterine, or 
Uver-iat, is not saponifiable. it apixars as a product of disintegration, 
increaBing in quantity during acute diseases. Tlie proportion of this sul>- 
•tanoe increases after 40 years ; it also forms a principal ingredient in 
biliary concretions. 

Among the vpocial constituents of certain portions of the venous blood 
not mentioned in the preceding tables, wo ought not to over- 
look wipir, which exists as a constant ingredient of the blood 
contained in that [lort of the circulation inten'ening between the liver and 
the longs. This, which is known as liver*sugar, may have originated in 
tbo tranamutation of cano-»u^^r, or from the metamorphosis of the mus- 
caUr tiasucs. It b to bo remarked that the blood contaiua so gelatine. 



i^_ 



k 



124 



THE MINERAL OONSTITCENTS OP BLOOD, 



Conipwbon of Xo the mineral subatancea in tlie cdb and plasma of the 
cunftUitiniuof Uood Tcspecti vel y, attention should be paaticularly directed, 
**r^^ '"'* aincc they indicate the functions of these portions. 

JTtMml 0»utUMMU in 1000 l\trU of tKe Bhod, 



Chlorine 

Snlpbnric odd 

l*h(M)ilioric odd 

I'uUuoituu ..». 

Sodium 

Oxygen 

]*hos]thato of lime 

l'ht>>fptiut« uf ma^Cid* 
Irua excluded 



(.»IU 



O.lMtG 
MM 

l.(»3 
0.lk>7 
UlIU 
0.078 



8.120 



3.t;44 

0.1 15 
0.101 
0.323 
8.A41 

o.iu:) 
0.311 
O.Si3 



8.550 




Tlie amount of inorganic matter in the colls and plasma, respectivclTi 
of 1<X)0 pnrt.«i of blood licing nearly tlie same, the table shows that then 
is more than twice as much clilorine, and more than three times as moch 
sodium in the plasma as in the cells. It may thence Iw inft^red that the 
chloride of sodium is, for the most part, in the plasma. Moreorer, 
is six times as much phospliorus, nn<l more than trn times as much 
tossium, in the cells as in the plasma; anii therefore it may be inferred, 
since potash is required to so great an extent in the nutrition of the mus- 
cular system, and phosphorus as an clement of the pliosphorized oils ta 
the nervous, tliat the cells have a direct functional relation to those Lm- 
[mrtant mechanisms, and this in addition to their doty of introducing 
osyj^n. 

The mineral constituents of the blood discharjje vor dificrent duties, 
Funrcions of Bomc, cither directly or iitdirecrly, acting functionally, otlicxs 
^^^ "!'^"' as histogenctic bodies. Thus the alkaline properties of the 
thi' hiwwL blood are due to the presence of the carbonate and phosphate 
of soda^ and this latter substince enables the scmm to hold in solution 
carbonic acid, and thus it maintains a relation in the resjnratory opera- 
tion. Hut the phospliale of lime discharges a true liist^^netic ttinction, 
since upon it the bony system depends for its nutrition. The mutual 
relations of these sub.itnnccs are, of course, very complex, though oft«n 
of importance- Thus, of the two just mentioned, the phosphate of soda 
enables tlie scrum to hold the pliosphate of lime in solution. 

The ta\vny coloring matter of serum differs from cholepyrrhin in not 
Coloriiic raat- yielding the characteristic reaction of that body- The tint 
tfforwniiu. sometimes becomes quite deep, owing to several different 
causes, such as the undue accumulation of the coloring matter of xirine, 
through disturbance of renal action, or from bile pigment, as in icterus. 

The gases which can be di-sengaged from the blood occur in the cells, 
according to ilagnus, a statement which, liowcvcr, is very far from being 





PTTNCTTOKS OP THE CO^WI'ITIKN'IS OF BLOOa 



125 



I 



eal^tanttated : they are carbonic aciJ, oxygon, ami nitrogen. Ga,e» of the 
lie tuimd tiwt tliia li(iuid can absorb once and a Iialt" its vol- '''«"'• 
amo of carbonic acid, and that in arterial blood tho proportion of timt 
wad to oxygen ia as IC to G, in venous as IG to 4. Tlmt tiie oxygen 
ia \(Ty loosely retained ia shown by the circumBtancc that it may for 
the most part be removed by ex])0!*urc in a vacuum. The other gaaca 
may be withdrawn by a Rtreom of hydrogen. 

At a tc-m|jerature of 98*^, water alworba scarcely one per cent, of its 
volume of oxygen gas, but tlie blood can take up front 10 to 13 limes as 
much. This is accompliHhed by tlie coloring material. The amount is 
iDdp|tendent of variations in the pre.ssurc of tlie air, which would not be 
llic case if llicgaa were i-eceived into the circulating fluid by mere solu- 
tion. This is the opinion of Licbig, by whom it is regarded as being to 
some extent pubstautiated by the fact that the respiration 18 accomplijihed 
with nearly tiic same result, so iiir as the ab8orj>tiou of oxygen is con- 
oemcd, at considerable heights above and at the level of the sea, and thai 
no more oxygen is received from an atmosphere very rich in tiiat gas 
than from the ordinar)' air. Jlowever ci>rrect this view may be, the fiicts 
cited in its support ore very far from being undeniable. 

The preceding chemical examination of the siweial constituents of the 
bUiod leads us next to consider the general fuJictions of this liquid in the 
aggregate. 

In this general sense, the blood discharges the iViUowing oificcs. Its 
«Ummen hiL? tho duty of gi^'ing origin to all tlio plastic tis- cp„pr»l si«w- 

of the syiftcra. From it, for example, by cell action, as raont of ii>« 
ex|daine<l in treating of lacteal absorption, fibrin arises — (S" rflffervm 
fibrin, which ia used for the renovation and re(«iir of the mus- coMUiocotoof 
color tiasoca. The discs have a rebtion with the function of 
respiration; they obtain oxygen in the pulmonary circulation, and cany 
it through the system. Tlicy contribute, moreover, to the development 
of muBCutar libre, and also nervous material, and tins not alone as regards 
the coloring matter of those tissues. Tho fata are necessary in tltc pro- 
duction of fibrin and for the nuclei of cells; but, besides these hiatoge- 
nelie relations, they eventually, with the exception of liver-fat, undergo 
oxidation, and so minister to the support of a high tcmpt^ature. Of the 
saline substoucea, common salt pnniiotes digestion by aiding in the ]in'|>- 
aratiun of gastric and puncrealic juices; the phospliate of soda enables 
the jilaoma to bold carl>onic acid in solution, and carr^' it to the lungs. 

It ia interesting to observe the limits of variation which the bloo<l may 
present in disturU-d or diseaaetl conditions. In intlammationa, tlie fibrin 
may incicasc foorfold; in t^'phoid fevers it may diminish to less than 
ODQ hali^ and trom these variations special results may arise. Thus 
diminution of its fibrin disposes the blood to preternatural oozing or &- 





126 CHANGES IN THE ClfiCt'LATIOV. 

cillty of ('^cap«>. 80 also tlic ccIU hnrc been known, in coses of cUon> 
sis, to Rink to one fifth of tlie healthy amonnt. The albumen, too, ei- 
liiljits like variations. In Bright'a disease it prreatly diminishea, much 
of it escaping in ihe urine by the straining action of the kidneys. 

Tbnfl constituted, the blood, by a inechauism to be described in llie 
next clmptcr, passes from the heart altematelv to all parts 
riDi;<)uri»(;tbe of the systeni, and alternately to the cells of the lonj^ pr- 
emulatioo. ^^ ^.j^ ^^ what liave l»eon termed the greator and less dr- 
cuhition, or the systemic and ilic pulmonary. In the systemic circula- 
tion, the blood, which leaves the heart in an arterialized condition, or as- 
sociated with atmosphcTic oxygen, gives up that element to the Tarioiu 
tissues as it pervades them, and accomplishes a double result : tlie re- 
moval of all those particles which, having; discharged their duty and on- 
deigonc partial or periuct interstitial death, arc ready to jwss away, and 
also the liberation of a great amount of heat by the destructive oxidation : 
so, at the same time tiie wasted matter is removed and advantage takea 
of it to raise the temperature of the body. This done, the blood tttskea 
its way back to the heart, following the channel of the veins as thry suc- 
cessively converge into tninks that are lai^r and larger. At the mo- 
ment of surrendering its oxygen and receiWng the various products of 
combustion, a change of color occurs. The bright crimson turns to 11 
deep blue, and the blood presents itself of that color at the heart. 

It now undergoes the less or pulraonory circulation. Leaving the 
heart, it passes over the air-cells of the longs, and i.s ihcro exposed to ti»e 
aerating action of the atinosphcre. From the interior of the cells the 
discs receive their supply of oxygen, the plasma surrendering up carbonic 
acid and tlie vapor of water. The color now changes back from the 
blue to the scarlet. In this condition it returns to the heart, to be dis- 
tributed in the systemic circulation once more. 

During this double round an incessant change is taking place in the 
Um oiiTioni constitution of the blood: it Is undergoing a continuOTis met- 
i>iit Important amorphosis. In some respects, as, for instance, in color, 
" "**** this is obvious enough. But the invisible changes infinite- 

ly exceed in importance and amount those that are obvious to the eye. 

All the soft tissues, since they arc wasting away, require repair. 
This, inasmuch as it is accomplished either directly or indirectly by tlie 
albumen of the blood, gives rise to a constant drain of that substance, 
and demands a constant supply, which is provided by nutrition or stom- 
ach digestion. 

The cells, wliich constitute the other chief portions of the blood, are 

necessary to the production of a high tcmpcmturc, by con- 

oxygtu by tbe stantly transferring oxygen from the cells of the lungs to 

'*^- every part of the body; carriers of oxygen they have been 




[•AL DE8TIU:CTI0N OF BLOOD-CELLS. 



127 



hily rnllcd. That tUia is one of their duties has teen proved experi- 
mentally, for a ftolutioii of albumen or tlic Berum lias but little power of 
tbfiorbing oxygen, scarcely exceeding water itself in tb&t res]M:ct, but 
Jic discs condense it at once. The ciiange of color tltcy exhibit as tliey 
dtemately gain or loso that clement, is in itself a proof of this fact, as 
> also the action of serum or blood-discs respectively on a measured 
rolume of air contained in ajar. It' the discs be in the venous or pur- 
»le condition, they quickly absorb oxygen from tlie contined air, whicli 
tbei«foro at onee diminishes in omonnt, but the ecnim, or a solution of 
klbumcn, produces no such eft'ect. The plnsma serves, therefore, for the 
pneral niilrition of the system, and the discs, by transferring oxygen 
mm point to point, discharge tliat port of their duty which is conneet- 
id with the production of heat. 

Bat the discs, tliough of a flattened form, arc truly cells, and all that 
obtains in tho eafio of cell bfc and cell action obtains for irjHiMtorr du- 
betn. They have not a duration at all comparable to tho mtiun uf Uie 
oration of tl»c system, but are constantly coming into ex- *' 
kteocc and disapj)caring. Kacti is an individual having it» own partic- 
liar history, its lime of birth, its time of maturity, its timo of death. 
Soch passes through a series of incidents proper to itself. Originating 
been destcribcd, they grow at the expense of the plasma, and in 
d it serves for their nutrition as well as for that of the body 
Jly. 
Ou exposing blood-cells to oxygen and carbonic acid gases alternately, 
here is not only a change in their shape, which becomes eormgatcd and 
itor-liko, but also in their c]ieniical constitution, so that, after such an 
ucposnrc of nine or ten times, they arc entirely destroyed. Such alter- 
itions occurring in the system doubtless lead to the same result, though 
ore slowly, since the oxygen is presented in a diluted condition. 
The corrugated and star-like blood-cells abound in the blood of the 
>rtal, though not in that of the hepatic vein. If their aspect 
from their tendency to disintegration, this is no more 

"^ '* than might be expected in view of the fitno 

tions of the liver. That the stellated aspect 
is an indication of a commencing disorganiza- 
tion, or other profound cbangCT may be illns- 
tratcd by an examination of tlie action of wa- 
ter on normal blood-cells, which, if Uiey be 
exposed to that liquid, undergo a distention ; 
their thickness increasing more rapidly than 
their diameter, they loso their conca\'ity, be- 
come convex, and at last ap|>enr as spheres 
Mu^ w^^M» n^dikd M» ^( ^ i^gg gij,^. tij^n ^(j^ original discs. AVhca 




Dyini: celta. 





128 ABSOCIATIOK OF HJEOUTIN AND OXTGEir. 

the quantity of water they have received has distended them to their at- 
most capacity, they then are invisible ; but when it is withdrawn fron 
them by establishing exosmosis through the addition of saline sub- 
stances, they may reappear in the corrugated or star shape, as seen in 
the photograph, Fig. 60, 

With rcsi)ect to the action of the hsematin, it may be observed, that 
. . ,. other nitrogenized coloring materials present a similar idir 
aiin illustrated tion to oxygen. As an example, indigo may be mentioned. 
V mdigo. J consider that the properties of this substance illustrate in 
a significant manner the properties of htematin in the system. Indigo 
occiu-3 in the leaves of the plant which yields it in a yellow and soluUe 
state. It is easily extracted from them by maceration in water. Ex* 
posed to the air, it absorbs oxygen, becomes insoluble, and simultane- 
ously gains a deep blue tint. So lightly is the oxygen thus united to 
it, that by exposure to very feeble agents it surrenders it up, and repasses 
into the yellow and soluble condition. Once more exposed to the air, 
it turns blue, and once more may have that color removed fix>m it by tak- 
ing its oxygen away. For many times in succession its tint may be 
thus changed, and made yellow or blue at pleasure. 

From this we perceive in what a loose manner oxygen is held by such 
a coloring material ; how readily it surrenders it, and how readily it re- 
covers it. Such a union can scarcely be called an oxidation or a com- 
bination ; it is rather an association. 

All this is i)rcciscly what occurs in the case of heematin. It takes up 
Feehieonionof ^^^^^ ^^>^*» rapidity as it goes over the cells of the lunga, 
oxygen and and tums scailct ; it surrenders tliat oxygen with equal fa- 
icmatin. cility as it passes the systemic capillaries, and tums blue. 
This change of color is incessantly taking place ; it is now red, and now 
blue, as the cells arc passing in the greater and the loss circulation. 

Formerly it was supposed that, in the act of respiration, oxygen from 
Eeception and the air united with carbon of the blood or of the cells, and 
of'oxvccn'bv carbonic acid formed, a combination or perfect oxidation 
tiie biood-ceUs. faking place in the lung. But, if this were true, the tem- 
jTcraturc of those organs should be higher than that of the rest of the 
body, and this is by all admitted not to be the case. 

The cells arc therefore carriers of oxygen. Tliey receive tlmt vivify- 
ing principle as tliey move over the respiratory cells, and, freighted with 
it, pass to all parts of the body, not united with it, nor disorganized, nor 
burnt up by it, but holding it loosely, and ready to give it up and go 
back again for a fresh supply. 

The sac containing the haematin offers no kind of resistance to these 
exchanges. It will be fully demonstrated in the chapter on respiration 
that this is the case. Thick pieces of India-rubber, stout animal mem- 




CIBCULATIOX OF THE BLOOD. 



129 



tor even massei* of stucco, present no obstacle to the passage of 
TJ»e delicate wall of tlie:4C cells, a tissue of almost inconceivable 
', can offer no resistance. The gas poAsca in and out without ira- 
I ».^ut or restraint. 

1^ But ihoitgli in this manner these little organisms perform their duty^ 
Htt is only for a time. They may take oxygen from the air- j, . 

" cells and give it up in the system, and do this jicrhaps many ihefururUon rf 

(thousand times, but it comes to an end at last. The incos- "'****^'*' 
Bant motion stops, and the worn and exliaustcd disc is brought to its term. 
By di'j^nties, as old age steals over it, it becomes corrugated and relaxed, 
is unable to witlistand chemical reagents, as its younger comrades can 
do. Through the microscope it seems puckered and attenuated. The 
b red color of its interior deteriorates into a tawny tint. As with a leaf in 
P the autumn, ilie natural color of which disappears, and yellowness or 
other cbangG precedes its fall, so with the dying disc. Unable any 
longrr to dlst-liargo its duties, its existence is brought to a close, the de- 
cayed luematin is shed oat to give a transient tawny tint to the plasma, 
tut is presently strainwl otf as one of the constituents of bile by the liver. 
Kor ia tlie illustration here used wholly metaphorical, for, in tlic case of 
■ herbivorous animals, Herzelius lias sliown that the coloring matter of their 
I bile is identical with clUorophyll, the coloring matter of leaves. 

^^^ CHAPTER VUL 

OP TITE CIKCLLATION OF THE BLOOD. 

n* ttmrt m a ifaeAuu. — /nac&'TMry of llitrtr^n Jortrme of the Cirmintitm.—Pkifneal /Vm- 
c^4» y lir Grrmiahon t applltU in t/ie itun^ of n jNV/nifA/ Ceily J'ervitMS 'fUmr, Motion of 
Sap ami V" Himtt. — /Jrpfwlnee ff tU Cirntiation on litrpirution. — Forwf nf Cirmlatiam : 
SfMlamet P^immtry. iWUit. — OrfrripHoH oflbe Jlenrt : its Afmxmentt. — Tkrir Forcr, \tm- 
ktr, ami VaUe. — ■Sountlt of the iltart. — Ojmm (^' iu CbfirnKtJm«. — XMaeriptioR ^ (Ae Arit' 
ritw, Ovm/£:uVj^ Vtiaa. — Kxjtiitnntion of the Gnviatim i^ tkt JUeod. — Fa^a »apporii»y it,~— 
71W Flr4t Umatk. 

No ftmction of the animal mechanism illuslrales more strikingly the 
doctrine that we must rely on physical agents for physiological explana- 
tions than tliat which we liavc now to consider, the circulation of the 
Uood. 

W« sDirender some of the most beautifid recollections of classical 
mjlhoh^, and some of the most chorished jjopular illusions xbo huat ■• 
of our own times. The heart, which in the higher classes of •" «>»'o«^ 
life is the central organ of impulse of the circulation, is to be degraded 
into a mere euginc. Wc have to speak of ita valves, its cords, its pipes. 



130 cmcuLAnoN of the blood. 

We have to consider its exhausting and its forcing action — to deal with 
it just as we should deal with an^ hydraulic apparatus. In the old 
times this organ was looked upon as the seat of the thoughts and the 
passions ; it was the centre of all good and evil, puri^ and uncleanness, 
devotion and love. In the modem system the brain has succeeded to 
the functions which were once imputed to it. 

The heart, then, is no longer an altar on which flames are burning, no 
longer the seat of the passions and the source of lore. It is a machine, 
but what kind of a machine? llow great is the admiration we may ex- 
press at its exquisite construction ! This little organ can execute three 
thousand millions of beats without a stop ! In the course of a liie, sncli 
OS wc sometimes meet with, it has propelled half a million tons of blood, 
and, though momentarily wasting, has repaired its own waste all the time. 
The mathematical rhythm of its four moving cavities, the perfect closure 
of its mitral and semilunar valves, and the regurgitating play of its tri- 
cuspid, have never failed it. To the eye of the intellect there is nothing 
lost in transferring it from the regions of metaphor and speculation to 
the domain of physical science. 

The doctrine of the circulation of the blood was first propounded by 
llarvey's doc- Dr. IIabvev about two huudrcd years ago. It originated 
cuUtion'tf the ^" *^® discovering of the valves of the veins by Fabricins ab 
blood. Aquapendentc. After many years of discussion, it was re- 

luctantly received by the medical profession. 

In this doctrine the circulation is referred to causes that are purely 
mechanical, in the strictest acceptation of that term. The contraction 
of the walls of the heart propels ti:e blood through the arterial tubes, 
and even through the veins, the direction of its movement being insured 
by a proper arrangement of valves. 

But when comparative anatomy and physiological botany were more 
Its imncrfcc- cxtcnsively cultivated, it was seen that this doctrine is insuf- 
tions. ficicnt, for the unity of nature forbids us to believe that nu- 

tritious juices arc circulated in different tribes of life by different forces. 
And though it may be that the contractions of that central impelling 
mechanism regulate the circulation in those organisms which have a heart, 
what is to be made of those countless numbers which have none ? In 
this group we find the whole vegetable creation, and a majority of the 
animal. 

There is a physical principle whicli lias long appeared to me sufficient. 
rhypicai prin- Its usc in an explanation of the motion of nutritive juices in 
?n theca*i'iiarT o^g*"izcd systems of every class I have taught in the Uni- 
circuiation. vcrsity for many years. It possesses the advantage of gen- 
erality, since it is applicable in every case, from the circulation taking 
place in a closed cell up to that of man. 



PHYSICAL PKTXCIPLE OP THE anCfLATIOX. 



In CliaplcrVI. is a general statement of the phenomena and laws of 
I capUlury attraction ; the principle now to bo employed is closely coiinect- 
Icd therewitlu It may be stated as follows; 

If two liqtiirlft communicate with one another in a capillary tube, for 
[the snbstance of which they have affinities of different intensities, niove- 
jment will ensue: the liquid having the bighcat affinity will occupy the 
tube, and may even drive the oihcx before it The same effect will en- 
sue in a porous stracturc. 

Fi}. fti. l*hns, let A, A, J^iff. 51, be a capillary tube 

iM^MgiB^giMg— of any kuid, which is occupied conjointly by 

Uouao ta • t»i>ui»i7 i"i«i. two liqui Js, a and t\ meeting each other in 

I its middle, c; a having a high and v but little affinity for the substance 

I cf which the tiibe consists, a will occupy the tube, pressing out v before 

it. Of course, it is to be understood that llic liquids a and v rc8j>cct- 

ively commuuicatc with reservoirs tliat can furnisiL them a necessary 

supply. 

J^Tiic various plicnomena desnril»ed nn(b*r the deslgnallon of endosmo- 
arc experimental illustrations oftiic same kind. Thus, , ^ .. . , 
when water is pat on one side of a piece of bladder, and nl- expUtnaion ot 
cohol on the other, the water, having the highest affmity for """"°" ■ 
the substance of which the bladder consists, occupies the pores thereof, 
and cxpeU the alcohol. Nor would any of the latter substance find-its 
way in the opposite direction, back into the water, were it not so soluble 
or diffusible in that liquid. Kxosmosls therefore takes place through 
tlic water, and constitutes a very subordinate or feeble current. 

Xow it is precisely relations of this kind that arc observed in the case 
of the circulating and nutritive juices of all organic lacings. 

The simplest instance is presented by the fluid contents of certain nu- 
clcafcd cells, both among animals and plants, in which a cur- „. . . . 
rmt moves towanl. anil tlicn from, the nuclcns, coming back nntlMtol 
in a returning path. The tluid which the cell contains yields ** ' 
I to ihc nucleus, in wliich seems to be concentrated all (he activity of the 
organism, the nutritive material it requires, and, this done, passes on to 
make way for other portions. The act of nutrition, thercfoi-c, is followed 
by TDOtioR, and this upon the above simple principle; for the liquid, be- 
fore it approaches to the nucleus, is charged with material which Ihc nn- 
I cleus can attract ; but immediately af^ contact has taken place, and the 
I has Keen mmoved, the liquid maint^uns no longer any relation witli 
. the affinity or attraction is satisfied, and, so to epoak. it loses 
r its ' reupon, and is pressed off by new-coming portions. Before its 

B a[)ptX)Acb, and after its departure, the liquid has opposite relations to the 
H uocleus, and in this respect may be regarded as representing two liqnids, 
H the one having a high ofiinity, and the other none, for the nucleus. The 




133 



CTRCCLATIOX IN CEUA 



F%;B1 




circulation in rentable ccUs ia shown by tlie < 
rcction of the arrows in Fig, 52. The connetakea I 
by the current may be determined under the mi 
croBcopc by the minntc tloating, or, rather, driftin* 
granalcs. It ia to and then from the nucleus. 



^^ta 



talU. 




LltvuUtlg« in TfiilMfMli 



I'\g. 53 represents one of 
(ho jointed hairs from the 
TnuleacantiaA'irgiiiica. The 
engra\-ing ia from the Wcw 
given by Sir. Slack, correct- 
ed, liovever, by the aid of a 
photograph of a similar ob- 
ject, ff, A, c, d arc the suc- 
cessive cells oft lie Imir. The 
dotted lines show the direction of the current to 
and from the nucleus. 

TIic Juice which is nlwnt to nourish a jiart has 
CJretiUtioo *°' *^"** P**"*' * certii" affinity, but, with the accomplislimcnt 
throiiKh pCT- of that nutrition, the affinity is at once lost. Thus, for in- 
«"l«>ftfc giniipc^ in iiic systemic circulation, the parts to be nourished 
have a certain affinity for tlic arterial bhtod ; they take from it wIialcr^H 
their purposes require, and, that done, tlie relation at once ceases ; the 
blood, become venous, has lost its Iiold upon them, and is pressed oC 
We may conveniently describe this effliict as a pressure of the anchan 
U}K>n the changed liquid. 

The motions of the sap in plants arc clearly dependent on this pri: 
Kxplu)*^^ o' ciplc. Leaving out of consideration the minor movemcn 
^LirfiilsMji ^Ji'ch take phice for special purposes, or at specitic opoc 
ofpUou. in the development, it may be truly said that the nutritii 

changes occurring in the leaf arc the jirimary cause of the motion; for.; 
the ascending sop presents itself on the sky face of the ie.if, it receives 
carbon, under tlie inllucncoof the 8uniiglit,from the air, and becomes con' 
verted into a gummy, glutinous liquid. And just as in the piires of a 
bladder, or in (hose of any pervious mineral, pure water will drive oidfl 
gum-waler. and occupy the pore, so will the ascending sap expel thii^ 
gummy solution from the capillary tubes or intercellular spaces of the 
leaf. As fast as this takes place, the active liquid becomes inactive, bjfl 
itself changing into a gummy solution, and the movement is perpetuated. 
And this ensues not only in the leaf, but in everj' part of the jdant ; the 
liquid to be changed presses upon that which lias changed, and forces 
it onward. In this manner, motions in various parts and of very grea 
intricacy will ensue, but all of them, if duly considered, no matte 
whether their seat be in the root or in the bark, in the flowers or in tl 




CirSE OF TDE CAPlLLAlty CinCOLATIOy. 

matter wlietlicr tlicy take place in the liciglit of summer or 
jiwt at the close of "winter, wi»cn tlic sap first rises, or even in the germ- 
inating seed which ia under the ground, and has never yet been ex|«>sed 
to tiie light, may, without difficulty, be referred to tlic nntrilivc cliange 
curried on in tl c leaves of the plant under examination, or its parent, by 
the influence of tlic rays of tiic snn. 

All this holds goo<l, not only in the nutrition of a cell, tho more com- 
plicated nutrition of the various parts of a flowering plant, or Rxpinnation yf 
even of an animal, hut likewise in those destructive changes cir'^.^*^t'ioo'^ 
• irstricted to the Litter class, and arising in interstitial decay ; uiimuls. 
for the blood has a double duty to |ierform : it not only scrvca for nutri- 
tion, but also for the removal of cftctc and dying parts. These it cflccts 
the oxidation of, thc'ur carbon possuig liito carbonic acid, their hydrogen 
into water ; and this is accomplished by tho oxygen which lias been ob- 
tained in the proceaa of respiration. The scarlet or arterial blood, charged 
with its oxygen, passes to all parts of tlic economy in search of organic 
particlea ready to be removed ; it efiects their disorganization, and, becom- 
ing thereby venous, ia pressed onward. And now, if we recall tliat nu- 
trition in animals depends on the access of air— even librin can not arise 
(mm albumen except under tiiat contlition — we can not avoid tlie con- 
cliuion tliat all operations of repair and nil operations of waste are made 
to conspire together for the production of movement ; and though every 
part otfers its own special cause, as depending on nutrition, or discnte- 
gration, or secretion, they may be all grouped together as the necessary 
n.*9nlts of one more primitive operation, which is the supply of oxygen 
to the blood in the respiratoiy mechanism. 

In my view of tliis sulject, it is therefore the arterialization of tho 
Uood in the lungs which is the cause of the circulation in p^ . ^ 
loan. I consider the circulation as the consequence of res- cinuUtion in 
piration; and though, in one sense, the minor causes are *^'""P""»''<«'- 
iiumei-ous, each portion of nervous material, each muscular fibre, every 
secreting cell working its own way, these subordinate actions arc all 
referable to one primordial act, and that is the exposure of the blood to 
the air. 

'\Viiate%-er, ihereforc, ijitcrfcrca with respiration, interferes with circula- 
Jf an irrespirablc j^as is thrown into the cells of the lungs, the 
of the blood is instantly arrested, and asphyxia ensues. Or, if 
t}ie access of the air is ent ofl^, as in drowning, in vain the heart exerts 
ifa utmost convulsive throb — it is unable to drive forwanl the Com of »»- 
Wood; and in those cases, by no means inire<iuent, yet un- Jpaiil'i"/™" 
doubtedly the most surprising occurxing in tlie practice of Jr»wma^ 
medicine — restoration from death after drowning, tlic whole success turns 
on one condition, the re-establi»hmcnt of tiic arterial izal ion of the blood. 



134 COUBSE OF THE CIRCULATIKQ BLOOD. 

If that be accomplished, the circulation is restored, and the heart pro- 
ceeds with its duty. And for these reasons, I believe that in many cases 
success would be had, where failures are now experienced, i^ instead of 
resorting to atmospheric air, pure oxygen gas or protoxide of nitrogen 
were administered. 

In the more Iiighly-developcd organisms the objects of the circnlatMHi 
arc tlireefold : 1st. To minister to the nutrition of the system; 2d. To 
introduce oxygen ; 3d. To remove the products of waste. In man, these 
various results arc accomplished by several different arraogements : Ist. 
_. _ The greater, or systemic circulation ; 2d. The less, or polmo- 
(lasAOA uf nary circulation ; 3d. The portal circulation ; 4th. The Malpi- 
circuution. gj^an circulation, &C. 

The course token by the blood is as follows. Leaving the left Tcntri- 
Coonteofthe ^^ of the hcort, it passes into the aorta, and is distributed 
tiooainitasy*. \)y the ramifications thereof, constituting the systemic arte- 
TOoiiar>°circu- ^^^^ to all ports of the system. It moves onward through 
latioDi. t]|Q capillaries, whicli may at once be considered as the term- 

inal ramifications of tlie arteries and the commencing tnbelets of the 
veins. These, converging into larger and larger venous trunks, the sys- 
temic veins, deliver it into tho ascending and descending Tense cave, from 
which it flows into the right auricle, and from thence into the right ven- 
tricle of the heart. From thence it is driven into the pulmonary arteiy, 
to be distributed to the lungs, and, coming therefrom along the pulmo- 
nary veins, reaches the left auricle, and from thence it gains the lefl ven- 
tricle, which was its starting-point. 

In the pulmonary veins, the left cavities of the heart, and in tlie sys- 
Distributionof *^™i*^ arteries, the blood is crimson. In the systemic veins, 
triiii:>on and of thc right cavitics of the heart, and pnlmonaiy artery and its 
ue oo. . branches, it is blue. Tlie change from crimson to Hue takes 
place in the systemic capillaries, and from blue to crimson in the pulmo- 
nary. The systemic, or greater circulation, is considered as beginning 
at tlie left ventricle and ending at the right auricle ; the pulmonary, or 
less circulation, begins at the right ventricle and ends at the left auri- 
cle. This double course is sometimes, among authors, illustrated by 
likening it to the figure 8, the upper loop representing the pulmonarj', 
the lower the systemic circulation, and thc heart placed at the nodal point. 

As has just been remarked, there are other subordinate circulations, 
The portal but of these oiily one need attract otir attention at present — it 
circuiaiion. jg thc portal. Tliis originates in a system of capillaries, the 
veins belonging to the digestive apparatus, which, convei^ng rapidly to- 
gether, form a common trunk, the portal vein. This at once ramifies 
like an artery in the substance of the liver. From the resulting capilla- 
ries, the portal blood passes into the commencing capillaries of thc hepat' 




* 



JV-M- 

4 



omoxx OF THE nn.viiT. 

ic veins, "wKich empty into the inferior vena cava, and bo it rraclics 
tbo gcnecal circulation. TI»c phyaical peculiarity of the portal cir- 
culation is, that it commences m a capillar}' system) and ends in one, 
rithont the intcr\"cnlion of any central organ of impulse, or licJirt. At a 
vcrj* ctti-Iy period, compnmtivc anatomists were struck with rorinl oin.-ul«. 
the analogy between the jiortnl circulation in man and the Jj,'!"!^"*,,'™*'^ 
systemic circulation of lishctt. both lK.':ini; carried on in the Mt. 
same way, that is, without a hoarU In tishcs, the heart is a branchial, 
respiraton.', or ptdinonary one. Their systemic circulation, or circula- 
tion of crimson blood, commences in the capillaries of the re.'ipimtory a]V 
paratus, the gills ; a con vcr^icncc takes place into on aorta, whicli rami fies 
into systrTuic capilhuies. tio the great circulation in these tuU'S is ac- 
complished without any heart. It is scarcely iicccpsary to point out the 
bearing of sucli a fact on the theories of the movement of tlic blood. 

Li J^iff. 54 is a diagram of the circulation of a fish ; (7, 
is the auricle; 6, the ventricle ; c, the branchial or pulmo- 
nary artery; fl, e, the branchial or pulmonary veiiu«, bring- 
ing blood from //, the braiicliiir, and converging directiv to 
j't the aorta, which dbttrilmtcs the systeinie blood. This 
is collected into a vena cava, g, and so brought to the au- 
ricle, a. There is tlicruforc no systemic heart. 

The further discussion of tliis subject will be continued 
as follows: Wn shall descril>o, Ist, the construction and 
action of the Jieart ; 2d, of tlie arteries ; 3d, of the capil- 
laries ; 4th, of the veins. We shall then present a view 
of the combined rasnlt of these various mcclianismg. 

1st, Tlic Heart The first appearance of the heart is oa 
a cavity arisinc; in a collection of cells, by dcli- 

.• r.i .11. The heart. 

quoacence or separation of tlio central ones. At 
this eariy period, and even before the cavity has fairly formed, pulsation 
may bo observed. The organ soon assumes a tubular tbrm; and this, 
j*^ oa. bocomtng curved, as shown in J^t^, 

55, fliiFercntiates into tlirce coropart- 
ment-s witli arterial ond vcjious con- 
nections; 1, the venous trunks; 2, 
the auricle; 3, the ventricle ; 4, the 
bulbus arterioBUB, The form to Iw 
erentaolly assumed is foreshadowed in the manner in which the curved 
tube develops, the arch of the curve, 2, bulging so as to fonn a conical 
▼entricle. This tri-cltambered heart remains (>emmncnt in fishes, as seen 
in tbB {veoeiling figore (54), of which c is the third chamber. But in binla 
mbA mammals, the aortic bulb merges into the ventricle, throntrh which, 
ai well as through the auricle, a septum or partition is established, and 




•lfT«IMl«iL 






JUtdlncnUfy iMmrL 





BTRL'CTTttE OF THE IIKJinT. 

tbtu a double Iieazt, or one of four dMB- 
bcrs, arises. 

The diajrrani, /Tjr. 50, represents a 
double-ciiauibercd heart, <i being its tarn- 
clo, e the vcnlricle, c e^ the Tcioa oonra^ 
in;; to the auricle, a the aorla or main trte- 
rv |ia*ntiig from tlic vcntricic. The coniBe 
of ihf* blood is indicated by the airoTni, 

The heart with Ibnr cavities may ht 
considered as arising from the conjunction 
of a pair of the preceding fomi, with ilieir 
cftercnt and afferent lubc«, or arteries 
and veihA, so niodiBed or amm^^l tluit 
the right heart receives ita blood troui the 
stem in en anrielc, from which it pusses into a vcntnclc, and tlicncc to 
Fia M. the lungs. From the lungs, after avratico, 

this blood is brought to the auricle of the 
lef^ heart, thence into its ventricle, and 
thence to the aorta. Though all four chan- 
bers arc gcncndly coalcs^-ed into one oonk- 
al form, the heart of the dngong, J^^, fi7, 
presents the true typical strncture ; E » 
ti)e riglit or pulmonary ventricle, L iImj 
or systemic ventricle, their apiccfl 
quite apart ; D is the right or systemic 
ricie, V the pulmonary arter}*, K the lefl 
n«in«ruic4»r»ii. piUmonary auricle^ and A the aorta. 

J^ff, 68 is the anatomy of the human heart as viewed upon the right 
Fit. to, side, the figure and description being 

from l)r. E. Wilson. 1, the cavity of 
the right auricle; 2, the apjx^ndix aU' 
ricuhe ; H, tlic superior vena cava, 
opening into the upper part of (he 
right auricle; 4, inferior vena cava; 
,5, the fossa ovaUs; the prominent 
riJge snm:)unding it is the annulos 
ovalia; (j, the Eustachian valve; 7, the 
oi>cnint; of the coronary vein ; 8» 
coroiuiry valve ; 0, the cntmnce of 1 
auriculo- ventricular opening; a, 
ri^^ht vcntricic ; A, r, the cavity of 1 
right ventricle, on the walls of vehli 
the colummc carnem are Been ; c is placed in the channel leading upward 





llsnu hmii on Ibe ricltl tUa. 




CTBCCn-nE OP THE nEART. 



187 



to the pulmoiury artery, d; e^J", the tricuspiJ valve : e is placed on tlie 
jintcrior cwrtain, and Z" on the right curtain ; *;, the long columna cameo, 
to tlic npt?x of which the anterior nnd riglit curtains of the tricuspid 
valvo are connected l>y the chorda? tendinen;; A, the long moderator 
Wnd I (, the two colummw eaniea* of tlie right curtain; X', ihc attach- 
ment by chordic tcndinoie of the left limb of tlic anterior curtain ; /, /, 
cbordn; tendincit* of the fixed cnrtain of the valve; m, the valve of (he 
pulmonary artery: tlie letter of reicTencc is placed on the inferior semi- 
lunar swjnient ; n^ the ni)ex of the right api>endix uui'iculas Oj l)ie luft 
ventricle; p, the ascendiuc^- aorta ; ^, its aR'h, with the three arlcriol 
trmiki* which aiise from the arch ; /*, the descending aorta. 

fif/. oii exJiibita tlic view of tlio organ on its left side. Like the pro- 
/^ ca. ceding, the figure and description 

are from Dr.WiJaon. 1, cavity 
of the left auricle: the numlicr 
is placed on that portion of the 
septum Qtiricularum correspond- 
ing with the centre of the fosaa 
ovalis; 2, cavity of the appendix 
jjirieulic ; 3, opening of the two 
rijfht pulmonary veins; 4, the 
sinus into which the left pulmo- 
nary veins open ; 0, the left pul- 
RM ' inonary veins; G, the auriculo- 

ventncular opening; 7, thecoro- 
vein, lying in the an riculo- ventricular groove; 8, the left ventriclo; 
the cavity of the let^ ventricle. The numbers rest on the septum 
riculorum. tt^ the mitral valve: its Haps are connected by chordas 
tendineie to A. A, A, tl»e columna; camew; Cf c, fixed colunma* carneas form- 
ing port of the internal surface of the ventricle ; f/, the arch of the aorta, 
from the summit of which the three artcriid trunks of the head and up- 
per extremities are seen arising; e, the pulmonary artery; /\ the oblit- 
irratetl ductus arteriosus ; <7, the left pulmonary artery; A^ llie right ven- 
tricle; i» the [joint of the appendix of the right auricle. 
Externally, the heart is covered by a serous membrane, |)cricardiura, 
Piy^fn. and in its interior is sheathed by the 

^^^^^^^^^^^^ endocardium, an extension of the inte- 

^^^^^^S^^SBS^^ ^^^ ^^^^ °^ ^^^ great blood-vessels. 
^^^^m^^^^Mp^^^ Though its movements arc wholly in- 
w^^^^^/S^^^^^S^SS voluntary, its muscular fibres are of the 

tnmsversely striated kind. They are 
nlMut one third less in diameter than 
those of voluntary muscles generally, 





138 COURSE OF THE BLOOD IN THE HEART. 

and arc csipecially characterized by their disposition to anastomose with 
one another, 03 represented in Fig* 60. In the ventricles, the arnuige- 
mcnt is such that the fibres of the external and internal sar&oes decus- 
sate. 

The motions of the heart consist in the relaxati<His and contractions of 
RcUxtti'ons the moscular walls of its cavities. The two auricles contract 
t^na^f tho" ®* *^® same moment, as do also the two rentrides, but the 
heart. contractions of the auricles coincide with the relaxations of the 

ventricles. 

The course of the blood tlirough the heart is this. The venona blood, 
Coumc of tho brought by the ascending and descending cavae, £owb into 
Mood in th« fije right auricle as it is dilating, and for the moment pushes 
movcmcnu of forwaid to the ventricle, but the auricle, being of less capac- 
the vtivcj. \^y ijj^jj ^Ijq ventricle, is filled to distention first ; at this in- 
stant it contracts, forcing its contents past the tricuspid valve into the 
ventricle, and fills it completely. The blood can not regurgitate into the 
veins to any extent while this is going on, because of the almost perfect 
closure of their valves. The right ventricle now commences to contract; 
its fioshy columns shorten so as to pull upon the tendinous cords attach- 
ed to the fiaps of the tricuspid valve : this enables the blood to get be- 
hind them, and they quietly close the aperture between the anride and 
ventricle ; the closure is not, however, under all circomBtances, perfect, 
the mechanism being such as to permit leakage or regurgitation to a lim- 
ited extent. The blood now rushes into the pulmonary artery, passing 
by its semilunar valves, which, the moment the ventricular pressure 
ceases, shut, so as to prevent any return to the heart. 

Having passed through tho lungs and been submitted to the air, the 
blood now returns to tlic left auricle, wliicli forces it into the left ventri- 
cle, the action on this side of the lieart being the same as on the other; 
tlic mitral vnlvc, which closes the oi^tening from the auricle into the ven- 
tricle, is worked in the same manner as the tricuspid, and the blood is 
pressed into tho aorta, the semilunar valves of which, at that instant, 
shut abruptly with an audible sound, and prevent any regui^tation. In 
this manner the distribution to the system is accomplished. 

On both sides of tlic heart, as soon as the auricles have finished their 
contraction, they begin to dilate, and continue to do so during the peri- 
od that the ventricles arc contracting. Thus there is an accumulation 
in them when the ventricles arc ready to dilate, and, as soon as tliat oc- 
curs, the blood flows finely forward into tJiose cavities, the complete dis- 
tention of which is then acconiphshed by the contraction of the auricles, 
as before explained. 

Movomontfl of The modc of action of the two sets of cavities is different. 
Mj*"niricio*. ^^'*^ tturiclcs contract suddenly, first at the place of junction 



MOVEMENTS OP THE HEAJtT. 



ISD 



of their Teui5» tlic effect passing quickly forward ; tlic ventricles con- 
tnict more slowly, but simultaneously in every part. 

I>aring eacli beat of tlio heart two sounds may bo hcurdf followed by 
a silence The 6rst sound is dull ; the second, which fol- Sound* of tbo 
Iowa it quickly, is sharp. They may be imitated by artic- *"^''*- 
oUting lUc syllabled lubb, dup. The first is due to the contraction 
of the xnoscular tibrcs of the ventricles, and the striking of the apex of 
tbc heart against tlic wall of the chest ; to a certain extent, the opening 
of the semilunar valves, aii<l the rush of the blood into the pulmonarj* 
artery and aorta contribute to it. The second sound is due to the shut- 
ting of the semilunar valves of the aorta and pulmonary artor^'. 

At cacli contraction of the ventricles tiie heart strikes against the wails 
of ihc chest, usually between the fifth and sbcth ribs, and an inch or two 
to iJie left of the sternum. This motion is partly due to the action of 
tbo spiral muscular tibrcs of the ventricles, which gives a lilt to the 
'Jwut, and partly to the globular form which the whole organ suddenly 
imcs. 

'ho number of pulsationa made by the heart differs verj' much at dif- 
ferent periods of lite: at birth it is from 130 to 140 per Kambcrofpul. 
minute ; at the seventh year, from 80 to 85 ; during mature »*>«"• 
life, from 70 to 75; and in old age, fiom 50 to ii't. In females it is 
snotc frcTjacnt tban in males. It obser>'es a gtJieral relation with the 
number of re'^jurutir)u». Hve pulsations commonly occurring during one 

Iicapiration. It vaiics with incidental circumstances. During sleep it 
declines in frequency ; after eating, or during exercise, it is quickened. 
Kxamined from morning to evening, it becomes slower by degrees. Ly- 
ing down, tiie pulse is slower ; in a sitting {>osture, more frequent ; and 
«tiU more ao when standing, the variations depending on muscular exer- 
tion. In conditions of disease, the ratio between the number of pulsa- 
tioufl and re-'^pi rations is variable. 
Tho wails of the left ventricle are twice as thick as those of the right, 
ftnd tlie force of its contractions is about double. Tlic ca- „. . a 

stniclarc ana 

IKtcity of tiie two ventricles is nearly the same, and is taken powur o( tiiu 

at about three oimcos. The active force with which the au- ** *" 
■ riclcs dilate is feeble, and wholly incompetent to exert any tiling like the 
F Auction power at one time supposed, yet that they are not distended by 

the mere influx of the blood is satisfactorily proved by their dilatation 

afier the beort has been cat out. 

With respect to tho absolute force which the left ventricle exerts for 

the pcopulsioD of the blootl into the systemic arteries, it is stated to be 

13 Iba. Tills result is derived from the consideration that tho pressure 

of iJiG blood iu the aorta is about 4 11)s. 3 oz. 

Tiiat the motions of the heart can not be referred to the presence of the 



» 



140 CAUSE OF THE HOTIONB OF THE HEABT. 

CauMofthe ^^^o*^ Of any reflex action arising from the cerebro-spinal 
motionB of the system, but must be attributed to the organ itself^ is proved 
""^ by their continuance after its excision from the body, or era 

after it has been cut in pieces. Some have supposed that the minole 
synipatlietic ganglia with which it is iiimished are the Booioe of the mo* 
tive power ; others are disposed to impute it to a aelf-contractiie power 
of its muscular fibres, irrespective of any nervous agency. Of comae, it 
is admitted by all that the brain and spinal cord can influence these 
movements, but such effects arc supcrad^d and not tmifonn. 

Of these opinions, wc shall find many reasons for preferring the first 
when wc come to the description of the nervous mecfaaniam. It will be 
then seen that one of the prominent functions of nerrous ganglia of a cer- 
tain order, and particularly the ganglia of the sympathetic, is the storing 
up of impressions they have received, and thus becoming reservoirs or 
magazines of force. The power tlius engendered or contained in than 
is by no means always delivered out in totality at once, but it may he 
in small portions, at intcn-als, for a long time ; and doubtless in this 
way the minute sympathetic ganglia of the substance of the heart retain 
a power of keeping up the motions of that organ for a certain period d 
time, even though great lesions or morbid clianges may have supervened. 
Sucli a mechanism recalls the manner in which chronometers are kept 
going during the short time that the action of the main-spring is taken 
off when the watcli is wound up. 

2d. The arteries arc tubes consisting of different tunics or layers v»- 
Dencription of Hously numbered by anatomists, but which may be soffi- 
thc artvnes. cicntly described as, 1st. Tlie exterior tunic, containing fibres 
generally running lengthwise, connective and elastic tissue : it is of about 
tlie same thickness as the tunic below ; 2d. The middle tunic, character- 
ized by being composed of non-striated muscular filnres circularly ar- 
ranged ; 3d. The interior tunic, which is thin, and consists of a cellular 
or epithelial layer, smooth and polished, to permit of the ready passage 
of the blood. 

TIiG elasticity of the arteries enables tliem to sustain the sudden action 
of tlie heart by distending to a certain d(^ree as the blood is driven into 
them, and by their gradual collapse when tlie ventricles cease their pres- 
sure, the jetting or intermitting flow is converted eventually into a con- 
tinuous stream. The mechanical influence of tlic heart is thus decom- 
posed into two portions : one, which is of momentary duration, or, at all 
events, lasting only so long as the ventricle contracts ; and a second, 
whicli is occupied in distending the clastic arterial tube; but this por- 
tion is not lost to the circulation, since the tube, as it contracts, yields 
it back again to the blood. The momentary impulse of the heart is thus 
spread over a considerable duration without loss. 



ACTION' OP THE ARTERIES. 

T!ie tnuscukrity of tlic arteries is bIiowti l>y their contraction on c,x- 
Burc, their Bobsequcnt dilatation being due to their elasticity, this con- 
PtxvctUe property being continued for some time after dcalli. It is also 
l|iro%'cd by the great diminution of diameter which arteries exhibit when 
limdcr the influence of an electric current. TIio quantity of muscular 
fid clastic tissue in ditlcrent arterial tubes is usually in an inverse pro- 
ion. In the great arteries tlic elastic tissue abounds, in tlic Bmuilcr 
'^the muscular increases. liy their muscular coat the quantity of blood 
in theae tubes can, within certain limits, be regulated. 

At each injection of blood into it an artery distends. It tbon con- 
[tracts, and thus gives origin to a pulsation. Its increase is Anion of the 
jbolii in diameter and lengtii, the tendency being to lift it at "t^rw*. 
leach pulsation. The distention docs not occur at the same instant in 
all thciM; tubes, but those nearest to the heart yield first, and the moro 
distant a little later. There is therefore what may be termed a wave of 
distention passing throughout the length of each arterial tube, and an- 
other actual wave in the blood itself. TIicsc pass onward at diftcrent 
nUca of g[«eed. The interval of wave-motion from the heart to the 
rrijtt ia about one seventh of a second. Of course this wave-motion is 
to be distinguished from the absolute movement of the blood, which ia 
mncli slower. In the carotid artery the dow of tJic blood is about one 
foot in one second. 

A pressure or impact, communicated to a liquid in a long tube, is 
transmitted to the more distant end with vastly more rapidity tlian tho 
liqnid itself could flow through the same distance. Thus, if we \verc to 
•Oppose a very long metnl tube to be filled completely with water, its 
two ends liaving lieen tightly closed by lying |)icce3 of bladder over 
tiian« the tap of a finger on one of the pieces of blatlder would be almost 
instantly felt by a finger laid on the other. Indeed, it has been pro- 
posed to establish telegrapliic communication on this principle, though 
each attempts would prove abortive from the interference of collateral 
carcumatanc^^ This example may serve, however, to illustrate the es- 
sential diflcTcncc betwtTii the flow of a liquid in a tulfc and the passage 
of a piiUalion tlirough suclt a liquid contained in smOi a tube. 

The capillaries may he regarded as tubular continuations of the arte- 
ries and tJie comnipnccmcnt of the veins. Thev ramifr „ ,., , 
ummgh the organic structures. Tlicy are of pretty unifurni 
diamrtcr, and may theretbre be looked upon as cylinders. Their usual 
■UEC is sIkjuI j-^-;^ of an inch ; their mode of distribution varies with the 
■trnclure and functions of the part they occur in : thus, in muscles they 
mn |»rallcl ; in the pnpitlie they arc looped. 

They consist essentially of a delicate structureless membrane, analo- 
gous to cell membrane, and the sarcolcmnia of voluntary muscles. It 




The intcTspncea between adjacent capillftrics vary nrach in size and 
Sbc of Inter- shape, llie Utter variation being de{x*ndcnt on tbe mo^ of 
^*™** distrilnition, whether parallel, reticulated, looped, Ac; as lo 

aize^ in the liver tho interspaces arc of less diameter than the eapillaries, 
in the choroid cont still smaller, but in tho cellular coat of (ho ftrtcries 
they nrc ten times lar^r than the vcsscU. These intcrstiti/d £>pacca arc 
nourished by the matter which exudes through the th!n wulls of the cap- 
illariea. 

Fku ca. Fig, 63 represents 

the capillary circtiU- 
tion in the web of the 
fnvrV foot : a, venoiiB 
trunk ; 6, ft, bntncbea 
ofvenous trnnk: f^c^ 
pigment cell*. The 
elliptical blood-discs 
are seen in oatliite in 
the interior of the ves- 
sels. 

The blood flows 
tlirough the capillar 
ricrt in an uninterrupt- 
ed etrcam, its jetting 
motion being entirely 
lost, Tlie rate of cir- 
culation through the 
systemic capillaries is 



STKUCTUKE OP THE VEINS. 



143 



;en at three inches per mimite, that througli the pulino- jf„,ion^tj,g 
being five times as quicks the length ot' the capillar)' tube h\>Md in tiie 
paaacd ^ of an inch, so that the {mssago from the ar- ^^ "'^ 
^yio the vein niay be accompUshed in 1ph3 tlian one second. It is to 
remarked, however, that tUl parts of tlic cylindrical stream do not 
ovc with equal rapidity. Those parts wliich are nearest to the wall of 
us vessel are sjmkeri of as the still layer, from their tardy movement. 
is in this that the white eorposcJea may be seen. 

p-'j- M. J^i^. 64 shows a portion of a small 

I vessel from a frog's foot: rt, a, red blood 

eUiptie cells, occujtying the axis of the 
vessel, and exterior to them, moving 
more slowly, or occupying the still lay- 
er, the white spherical cells ; i, 0, nucle- 
ated epithelium. 

4th. The veins have a stmcture in 
some respects dilfcrent from ti,, vfin*: 
that of the arteries. Their ti"ii'»truaurc. 
il'-'JoA l^KMPyfw— ' . elastic coat is by no means so much d&- 

veloi)ed, and their muscularity lesa dis- 
tinct. With the exception of those of 
mriiitc wrpn-'dM In the rtiu layer. th© lungs, abdominol viscera, and braiii) 

Elielr interior is furnished with valves of single, double, or triple ilaj)3, in 
U instances opening toward the heart. Thii blood ilows wjuably in 
phcm, the pulsating action of the ventricles having disappeared in the 
^pillarics. Since they present an nggregntc capacity two or three times 
hat of the arteries, the motion of the circulation in them is proportion- 
iJly slower. 7*7^. Go is a diagram showing the manner in which the 
ralvcs open when the blood flows in the course indicated by the arrows. 

f*7. CS. 



\ nlvt. \i{ vctiiK o;>iM. 



VaIviu of TtllU >hlU. 



Pz^. G6 shows their application to each other, or to the sides of the vein, 
ind the consequent bulging of that vessel when the current, as indicated 
>y the arrows, is in the opfiosite direction. 

Having now described the structure and action of the heart, the arte- 
iea, capillaries, and veins respectively, as far as is necessary, it remains 

group those actions together, and present the theory of the circulation 
it one view. 

But, before enlerine on this, it is proper to offer an ar- Errnrofihedoo- 

IT- , , t - t • . T. .11 iri»e that the 

ument agamst the doctrme of those physiologists who still ji^^rt U ih« wio 
nintaiu that the circulation is wholl v dependent on the heart, *■*"*". **f "'■ '=^'- 
no that that organ is entirely competent to carry it on. 



144 



ACnOX OP THE QEART. 



The majority of the circaUtiona ve examine in oi^iamc forms are «e- 
comptished without any heart. Plaiita have none ; tishes have no m- 
icniic heart ; oven in uian» at the first period of embryonii; cjtLstcncc, tlicrc 
is no such central organ ; in his adult condition the portal circuialiou bis 
nonf. The current of hlooU in the capillaries, seen under the microscope, 
cxhil)it3 no jetting movements, but, on the contrary-, a steadioen of 
Sow, sometimes for long in one clianuel, then a ccaaation, then pcdupt 
a rL'trogradalion, and tlien a new {uith. It looks as though the Uool 
was flowing spontaneously, and not by any force acting behind. Thr 
heart of an animal may be suddenly cut out, and yet tlie capillar}' motiaa 
may go on in the same direction as before. After death the arteiiftl 
tubes arc moat commonly fuund empty : a result which ia a mechankal 
Lin]>os8ibility on the supposition that the heart alone drivca the bloo^ 
but which ensues as a necessary consequence if the capillaries draw it 
In acanliac monsters the blood circulates without difficulty, and, though 
it was at one time supposed that in these twins the liearted fwtus drove 
the blood ihrougli the hearllcss one, this is now demonstrated not to be 
the ease. Tlic circulation, moreover, varies locally, and at special epochs, 
OS in the development of the generative organs, the mammary glands, tlw 
flow to the erectile tissues. Ubi irrilatio ibi fluxus Is an old medical 
aphorism, and these local variations arc incompatible with the action of 
one central unvaning force. In cases of f^pontaneoas gangrene, it some- 
limes occurs tliat ttie circulation through tiie part liaa declined, while the 
capillaries ore oil oj>en, as subsequent examination proves. The applica- 
tion of cold to a ]ULrt checks the circulatioa tlirough it, and this not 
through ary contraction of the vessels ; so, likewise, doe-s a jet of carbon- 
ic acid gas directed ujwn them. 3lorcovcr, any retardation in the supply 
of air to the lungs restrains the circulation, and this not aloue in tbe 
pulmonary vessels, but also in the systemic capillaries, produdog an iih 
crcased pressure in the arterial tubes, a diminished one simultaneotiair 
occurring in tlic veins ; and if, in the various eases now mentioned, tbe 
propulsive action of the ventricles can not be Relied on to explain the dit- 
lioulties, neither can any supposed suction or exhausting action of the 
auricles. When a ligature is tied ronnd a vein, the action of the auridu 
is cut off, but the vein distends l)eyond the obstruction, showing that 
there is a force acting from the capillaries. I'lexible tubes, sucli as are 
those vessels, would at once collapse under the exertion of a very modo^ 
ate suction ]X)wer, far less in intensity tluui would be nccessaxy to draw 
the blood in the veins. 

In spasmodic asthma, and in all pulmonary congestions, tlie right side 
of the iicart circulates the blood witii difliculty through the lungs, show- 
ing the existence of a great obstrucfion to its inoliou tlirough the pulmo- 
.lary cnpiliaries. An examination of the condition of the various por- 



CIRCULATION OP THE BLOOD. 



146 



[tionB of the circulatory apparatus after death presents facts utterly inex- 
I plicable on tlic doctrine of tlie sufficiency of tlic licart, I have already 
I mentioned tlie empty state of the systemic arteries ; to this may lie add- 
ed what is often witnessed — the distended condition of the pulmonary 
' artery, into whirii the blood has Ixsen forced by the expiring beats of the 
right ventricle, but has been unable to get through the pulmonary capil- 
1 laxieft because of the cessation of respiration; but in other cases, where 
[respiration has come to an end more ti*anquilly or slowly, the left auricle 
'is fiill of blood, which must have been driven into it by the pulmonary 
capillaries. In sudden death, as by hanpng and drowning, the right 
heart is excessively distended, as is also the pulmonary artery. 

I might ])rocced to add to these otlier facti^ exhibiting locjil variations 
of the supply of blood in the pcriodiritics of the system. There is a cer- 
tain amount sent to tlic bniin during the <lay, and a less during the re- 
pose of the niglit ; in the muscular system, during the time of its action, 
the quantity demanded is greater ; in its state of inactivity, less. A con- 
stant and invariable acting macliinc, such as is the heart, could by tio 
possibility adjust these vorialdc supplies. But the cases here oftered are 
more than enough, and it remains to be added that, though not one of 
them can be explained on the doctrine of tlic sufficiency of the heart, 
there is not one which docs not follow as a noceasary consequence of the 
doctrine now to be presented. 

On this view. 

The left ventricle of the heart impels the blood into all the KxpiunttMoor 
aortic branches, any backward rcgui^itation into tlie auricle tiiu circuUUoa 
being iTrc^T-nted by the shutling of the mitral valve; the " ' " 
force employed is decomposed into two portions, one part exerting au in- 
stantaneous efl'cct on the blood in pressing it fonvard, and ceasing in- 
stantanconjsly, and thus giving origin to the pulse; the second distend- 
ing the arterial tubes, but not being lost thereby, since their elasticity 
cauacs them to contract, and the semilunar valves at the origin of the 
aorta being at this period shut, a steady, onward pressure is exerted on 
tlie blood; so llie fjuickly-ending action of the ventricle gives origin to 
two distinct mechanical results — a sudden impact and a conlumous press- 
ure. This suifficca to bring the blood to tho arterial origin of the capil- 
laries, and beyond that point the action of the heart may be considered- 
not to extend. 

I The relation between the intcr3i)aces of the capillaries and tlie blood 
thus introduced to them continues tlie cmTcnt. Ttm particular motlc in 
which this relation is miuiifcsted dilferH in different partH. The oxidiz- 
ing arterial blood has a high affinity for those portions that have become 
wasted: it effects their disintegration, and then its affinity is lost. The 
rious tissues rcijuire re].«air; they liave an ailinity for one or other of 

K 



the circulation is conducted in the following mannerr 



146 aRCULATION OF TUE BLOOD. 

the constituents of the blood ; tliey take the material they need and thdi 
affinity is satisfied ; or secreting cells originate a drain upon the Uood, 
and the moment they hare removed from it the substance to be secreted, 
tliey liave no longer any relation with it So processes of oxidation, and 
processes of nutrition, and processes of secretion, all conspire to draw tbe 
current onward from the arteries, and to push it out toward the Tons; 
and though these processes may present themselves in many various as- 
pects, they arc all modifications of the same simple physical principle. 

The blood lias now reached the veins, and is forced onward in them hj 
the ^>owcr that has thus originated in the capillaries. The influence of 
the heart is here unfclt, the exhausting action of its right auricle is nn- 
appreciable, and, thus pushed onward from the capillaries, it reaches the 
heart, completing its systemic or greater circulation. This circulatioii 
may tlicrcforc be said to be due to the high affinity which arterial bbod 
lias for the tissues, venous blood having none ; and the action of the beut 
is confined to the filling of t!ie arterial tubes, and presenting &esh pw^ 
tions of blood to the capillaries. 

Arrived at the right auricle, the blood flows continuously into it and 
the right ventricle for a moment, but the ventricle holding more than the 
auricle, the latter cavity is fully distended first. At that instant it con- 
tractsi, llie valves in the veins shutting, and tlie blood, driven thus fordUj 
into the ventricle, distends it to the utmost. The ventricle, in its tum, 
now contracts, tlie tricuspid valve shutting, and the blood issues forth 
through the pulmonary artery, its valves then closing. At this moment 
an event occurs which, in these descriptions, is generally overlooked — an 
action analogous to that of the hydraulic ram. On the shutting of the 
tricuspid, the whole column of venous blood would be brought to a stop 
if the tubes containing it were unyielding, and a great force would be gen- 
erated from this stopping of its momentum ; but the auricle is ready to 
dilate, and into its cavity tlie blood, which would be otherwise checked, 
flows. I consider that this safety action of the auricle is one of its prime 
functions. The rapidity with which the dilatations and contractions are 
taking place furnish no argument against the occurrence of this action. 
I have a hydraulic ram, the pulsations of which may be so adjusted as 
to exceed greatly in frequency those of the heart, and, indeed, to give rise 
to a low murmuring sound, and yet, under these circumstances, the lat- 
eral force is so great as to throw a column of water more tiian forty feet 
high. If it were not for the dilatability of tlie auricles and their yield- 
ing texture, the veins would burst on the shutting of the tricuspid valve. 

Tlie ramiBcations of the pidmonary artery bring the blood to the cap- 
illaries of the lungs, but beyond that the influence of the heart is not felt, 
for now the physical principle heretofore described comes again into ac- 
tion. The venous blood has a high affinity for the oxygen of the air, an 



nm ITEARTS ACTIO!?. 



affinity wbich is siUisfiet! ns soon as tlic Wood presents itsc]f in Ihe cells 
of the liings. Artcrializatiou bein^ accomplished, the portions to bo 
changed exert a pressure on those timt li.ivo changed, and the blood, mov- 
ing forward in the pulmonary veins, reaches the left auricle of tho heart. 

For a moment it jwiases uito the left auricle and ventricle eontinnonsly, 
but the auricle, being of less eapocityt fiUa iirst. It contrncta as soou 
u it is completely full, and drives its contents into the left ventricle, dis- 
tending it to the utmost. The ventricle now contracts, shutting the mi- 
tral valve, and the ram-li!^c action is repeated on this side of tho lieart. 
But the blood expelled from tho ventricle is urged into tho aorta, its force 
being deeomposod, as before described, one part wrting instanfancnnslv 
as an itnpact on the blood, the other on tlie arterial walls, and on the 
first moment of tlic recession of tho walls of the ventricle the semilu- 
nar valves of tlic aorta shut, and tliis act completes one tour of the cir^ 
culation of the blood. 

In this description I have said nothing of tho circulation in the sub- 
stance of the hcjirt itself, since it would have led to a needless complica- 
tion. It should be rcmenil>ercd, as an illustration of the working of the 
physical principle here explained, that the motion of the blood is contrary 
in the gnyiter and less circulations, compared together. In the former, 
Ihc current is from the crimson to the blue, in the latter, from the blue 
to the crimson side. 

The action of t!ic heart is thei-efore limited to the (iUing of the arterial 
tubes, so as to present to the capillaries a constant supply of corrtci 8t«t*- 
blood. There seems to be but little suction force exerted meni of th« 
by the auricular cavities for the emptying of the vciiLs. Tho * *'" °°* 
valvular construction of these vessels economizes ever}' pressure that tho 
muaclca may exert on them in favor of tho circulation, for every sncli 
pressure must, by reason of the %-aIvcs, force the blood onward to the 
heart. This is, however, only an incidental result of the same character 
as the inilucnce which the motions of respiration exert. They may be 
properly overlooked in a general statement of the causes of the circulation. 

By regarding the affinity between tlie blood and tho tissues with which 
it is in contact as the great primary cause of the circulation, ^-^,^01^ f^cu 
we assign a reason for those varions phenomena which can supporting ihi* 
not be accoiuitcd for on llarvey*? doctrine: the motions in '^*** 
the embryo; the jjeriodic and local variations; the portal circulation; 
the clianges in the current, as soeu under the microscope ; the movement 
in the capillaries afYer the lieart is cut nut ; t!ie enii)ty condition of llie 
arteries after death ; the phenomena of ncardiac fa-tuses ; local infiam- 
nmlions and congestions ; the gangrene of parts while their capillaries 
are jK-rvious; t!ie retardation of tlie current on the ajiplication of cold or 
(f carbonic acid gas; the results of asphyxia and death by drowning or 



148 



THE FISST BREATH. 



Th« first bnsUi. 



han^g ; tUo changes of pressure in tlio arteries and TcinB respoctivelr 
during a ciicck on the respiration ; llie vis a tcrgo of the veins ; the effects 
of a ligature on those vesiela; the action of irrespiiable gases when 
breathed, and tho opposite conditions when oxygen gas or protoxide of 
nitrc)gcn aro nscd. 

Among the elriking proofs of the truth of tliia doctrine, that the pri- 
mary cause of the cinnilation is tlic aeration cf tlie l^oo<], I 
would particularly direct attention to the cfi'<xts which en- 
sue in the moment of birth at the tirst lireath. That intercom municatioa 
between the two sides of the heart, established through tho foramen oralo 
and through the ductus arteriosus, is suddenly put an end to. But this 
U not through any change in the mccluinism of the hcjxrt itself nor be- 
cause of any interruption in the action of the placenta. It is solely lo* 
cause of the calling into operation of the principle we liavc been lu-re en- 
forcing. Through ihc contact of the cold air, or other causes which mi^ 
be assigned, the inspiratory muscles make their first contraction and dia- 
tL*nd the lungs. At that instant, the commencing artcrializiition produces 
a "pressure, in the manner I have explained, of tho venous upon the now 
artcrialize<l blood in tlie vessels of the pulmonary cells. There is no 
other possible issue to such an action than an instant drain upon the 
heart. The pulmonary or leas circuhition sets in with full vigor. The 
blood is not driven by the heart to the lungs, but drained by the loB^^ 
from the heart. If it were the heart's action tliat occ.asioncd tliis sudflB 
increase of force, because of the strain tlirown tipon it through the shut- 
ting oflf of tho influence of tlio placenta, it is inconceivable why the cur- 
rent should not continue to move tlirough tJie great avenues already opeu 
to it &om the right to tho left auricle through tlie foramen ovale, and 
from the right ventricle into the aorta through tho ductus arteriosus. 
The arrest of its motion through these channels distinctly establi^ius that 
the scat of the new action is in tlio lungs, and the final closure of the 
foramen aud shriveling of the duct eonlinn the correctness of this con- 
clusion. 

Though it docs not strictly belong to the subject now under consid- 

fttion, 1 can not avoid impressing on the reader tho suddenness of tlie 
'effect that thus ensues on tho taking of the tirst breath. It in a crisis io 
the history of development. Of those cliangt'S by crisis nmch more will 
be said in the second book, and their important bearings on the the<iry 
of physiology pointed out It is enough for the present purpose to com- 
mend to the attention of those naturalists who deny that physiological 
crises ever occur, the facts wliich have been considered in the preceding 
paragraph. 

A doctrine which accounts with simplicity for such a long list of rois- 
ccllaneons facts commends itself to our attention at once. There are. 



OF HESPIRATIOX. 



149 



f Icwever, considerations of a still weightier character, which must compel 
OB to adopt it. The alTinity between tlic Wood and the parts with wliiclt 
it ia brought in contact is a chemical fact beyond coiilradictioiu The 
pressures atid motions I have been speaking of follow aa the inevitable 
consequences of that affinity. Wo can not, therefore, gainsay their ex- 
istence in the linng mcclianism, and the only doubt we can enTertain is 
fts to whether tliey arc of competent power to produce all tlio effects be- 
fore us. Bnt after what has lipcn already said respectuig the energy of 
cndosmotic movements displayed against pressures of mauy atmospheres, 
we may ab&ndon those doubts; and since we have Iierc a force of uni- 
versality enough, and intensity enoujrh, and in every instance acting in 
the right direction, it would be nrpiiilosophicnl to look farther, since such 
a force musty under these conditions, exist in tlie physical necessity of 
the case. 



CH^VPTER IX. 



OF EESFIRATIOK. 

fllUjrfillfi'iM mtmrbiea md renrarea aerial Smltftaiicai, — Ottikmxnte ^ Ra^iiratory md Urinary 
r in /TaAet. — Pkyncal and eAemieed Omdirions of Bay/imtion,^Iiatrttitiai MovtiMtOs 
fSUkUf TJqmdM, attd GaM»,—CoMStwH of £jtm£brmm in the IM^itntm t-f Gant^. — Om- 
' AcAm tf Utmbnmeji. — FormM ^ StjffiinWiry J/fcAonwwi.— Tfte L/angt vf Man.—' 
Tkrm ShtytJt iit ike Inttvlfctioa of Air : AtHtoMphrrie J ^est m r ry D\0'tuion ^ (>aae>, end 
OaaJauiUUm tg ^fanbrtma. — fCxcfttlrt^e of i^triioniti Arid/or Oiypm. — Dmnoiu of the Con- 
ttmtA ^ tht Lft'j'. — VoriatioHM ut thg e i p ir ed Air. — BrmornI of Wotrr. — Efftrt of imtptrvt- 
klf tiaaes. — ErjimmuttM ttf limputuk and BtUKl, — iS'envua Ir^jtvatct ameantd i» He^nraliim. 
— Htmtk* of lieytiration. 

Since it is essentially necessary to tlic life of all animals that the 
blood ahould pass to cverj- i>art of the system, provision must Ohj-ru of 
be made for iccuring aeration. The breathing apparatus is the "•P'Ttttiou. 
flkin, or some coctension, reflection, or modification of it. 

Besides the great duty of originating the circulation, respiration is con- 
nected with others of equal importance. Tlie functional activity of the 
nervous and muscular tissues is dependent on their oxidation, and this 
implies the introduction of air. In each tribe, moreover, it is necessary 
to kcf p the temperature up to a specific ]>oint. This also is accomplished 
liy oxidation, either of llio disintegrating material which is passing to 
waste, or of combustible substances, such as sugar or fat. 

All organic mati'.rial, at its death, eventually gives origin, -. . M«*iett 
ondcr the action of the air, to two products with wliich the orUaiH loai*' 
fhnciion of respiration is mainly concerned. These products ""*P"** '• 
aic carbonic acid and water. Witli the exception of gelatin, the other 



150 KATUBE OF BESPIBATION. 

respirator}- elements of food — fat, sugar, starch, &c., yield these two pro- 
ducts alone. The nutritive elements give rise to nitrogenized compounda 
in addition. The conditions of life are such that carbonic acid can not 
be permitted to accumulate in the system, and means hare therefoze to 
be resorted to for its remoral. The introduction of oxygen and excre- 
tion of carbonic acid are accomplished by the same mechanism, the Inngs, 
the action of which is dependent on a physical piinciple. 

Under its simplest condition, respiration consists in the passing of caz^ 
ReBpiration is Iwnic acid with the vapor of water from the system, and the 
connect«d with reception of oxvgen in exchange. The constmction of the 
porous matter apparatus wliich accomplishes this double duty in atmos- 
("^'y- pheric animals is such that it can deal with substances in 

the aerial state alone. Notliing con be introduced through the Inngs or 
escape therefrom except it be in the gaseous or vaporous form. All 
those products of disorganization wliich arc not presented under this con- 
dition must therefore be removed by other organs, and this is more par- 
ticularly done by the kidneys. 

* But in aquatic animals, as in fishes generally, there is not this restric- 
Coaie»ccnce of tion Or concentration of function, for the gill, being in contut 
Ind^S'wToZ ^'^^^ water, offers a channel for the passing away of many 
guu in tishes. products of wastc wluch, from their non-aerial state, could 
never escape through a lung, and so I regard this organ, the gill, as in a 
measure sharing the duty of a kidney m eliminating nitrogenized and 
perhaps saline matters. Comparative anatomists have long recognized 
that the so-caUed kidney in fishes approaches in character the Wolffian 
bodies largely developed in the fcctal condition of man. I am disposed 
to believe tliat the physical interpretation of this depoids on the &ct now 
before us, and that the gill in fishes, and the placenta, in part, in mam- 
mals, discharge at once the double office of a respiratory and urinary or- 
gan. It is consistent with tlie scheme of organic design that there should 
be this separation and concentration of function as development takes 
place. 

These considerations would therefore lead us to expect that we should 
find in the respiration of air-breathing animals that function in its purest 
and least complicated form, and this is accordingly the case. If it be 
merely the skin that is relied on, as in the low orders of aerial life, or if 
the mechanism be constructed on the type of carrying the air to the 
blood, as in insects, or that of carrying the blood to the air, as in num, 
the operation consists essentially in the escape of carbonic acid and 
Btcam, and the reception of oxygen in return. 

Bespiration, like circulation, furnishes us vrith a signal instance of 
the employment of purely physical principles for the accomplishment of 
physiological purposes. It is with the pressure of the atmosphere, the 



INTETtSnTTAL MOVEMrJTTS OF SOLIDS, LTQrTDS. GASES. 



151 



diffusion or gases, and the comlcnsiri"; action of inetnbraaes, ».,,_, 

t 1 11 (fit • • 1 n»y»tf»l prin- 

that we Ituvc now to dcaU X heac give us so precise and j>cr- cipi« kigaon- 
spicttous an esijlanation of the act of breathing that it is ^Ji^'j'„"*"!;j^' 
needlesfl to look beyond them ; yet on that act depend the ns|iinitor}^ m- 
itighest operations of Hfe. In ihU {tarticular tlic Scriptures ^""^ 
have summed up ilie deductions of modem physiology in a single line — 
no metaphorical expression, but the simple assertion of a truth: He 
*** lirentbed into his uostiila tlic breath of Itlo, and man became a liWng 
aotil." 

Of the physical prinriplcs now to be dealt with, it is unnecessary to 
aay any tlung respecting the pressure of the atmosphere, since that 13 
mU understood; but not su with the phenomena of the ditfu.siuii of gas- 
es, and the condensing nctiun of memliranes. Though tliese are subjects 
which Imve been particularly examined by American physicians, the facts 
they haTTC elicited arc little known abroad. Kor example, the error of 
Valentin's statement respecting the diffusion exchanges of carbonic acid 
and oxygen, and the uselessness of the elaborate discussions which have 
origiiiate<l therefrom, would at once have been recognized, had attuitiou 
been directed to the facts devclo]>ed here almost twenty years ago. 

lutrrstttial motions are exhibited by solid3, Htjuids, and gases. I 
luve had occasion to examine Roman silver coins, from the int«ntUtiai 
interior of whieli the cop|>cr originidly present had made its 3i*u«id Uq- 
Lirmy oat to the surface, forming the greenish incrustation w*!*- 
luiown OB patina by anti<[uarian3, the silver being left almost pure. In 
fpCAkbg of absorption by tlic blood-vessels in Chapter VI., we had oc- 
coaion to dwelt U])on the same propensity as shown by liquids, the eu- 
doiiniosis of Dotrochct being an example of it. The ready mobility of 
tliU group of Iwdica, arising from their diminished cohesion, greatly pro- 
mcktea these eflccts. llr. Doyle collected a nuu)ber of cases of solid movo- 
SDcuts in his tract on the languid motions of bodies. 

Gaacs and rapors, by reason of their total want of cohesion, present the 
most striking examples of these effects. Their propensity to intermin- 
gle with eudi otiicr is manifested, even though ihcy be obliged to pass 
liirifugh cre\ ices or winding jKissages. One of the iirat inslunees to which 
attention was directed occurred under the obacrvation of Dr. rriwiIPT't ob- 
Priestley, who fonnd, on passing steam through nii earthen ^j^eji'd^^^^ 
tulw placed in a furnace, that air would be dL-livcrcd at tho ofgM«. 
farther end« For some time he supposed that this cx|)eriment demon- 
strated the conversion of water into air by a great heat, but eventually 
Iraoed it to its proper cause — the escajw of the steam outward through 
tho pores of the earthen tube, and the intrusion in the opposite direc- 
tion of air from the furnace. This singular ex|ieriment may be well 
ahowo by attempting 1o pass steam tlirough a red-hot tobacco-pii)e^ tho 



EXPERIMENTS OF DALTON AXD GUAHAX. 



end of which dips bciicath some water. A torrent of gas bul)l>l«3 wiH 
escape. 

Air. Dalton demonstrated tlmt if a liglit gas be pUced alwvo a hca^T 
Dftlton'iutpcr- gas in a suitable apparatus, tbo former, notwithstanding iia 
levity, will dosceudt and the latter, notwithstaiidiiig its 
weight, will riiie, and n complete and uniform intcrmixtme 



lownlon tha 
dtAuIou of 



Fuf rt 



UtnuiMia of 



FfauM 



will result. By audi experiments he wa-s led to believe that 
gases act as vacua to one anotlicr, and correctly cxphiined the 
uniform composition of iheatniosplicre on this property ofdlf- 
^ion, or tendency of its constituents to intermix. 

Thus, if a vial tilled with iirdrogen be placed with its 
mouth downward over the mouth of a ^nal of the samo aize 
containing carbonic acid gas, as shown at A, r, J^ig. 67, in the 
course of a few moments the diBusion will be complete, and 
if the mixture in eitbcr vial be examined, it will be found to 
contain erjuni quantities of the gases. 

Professor (indium extended Dr. IVicstley's observations on 
Orahinn'i ex- ^^^^ passago through porous barriora. The sul^ 
pcrlnciiuirltb stance he chiefly emjiloycd was a mass of dr^"* 
pl.iBter of Paris. This enabled him to prove that 
in the case of different gases difiusion takes place at different 
rates, wbicli are dependent on the density of the gas. Per- 
haps the most satisfactorj' method of illustrating this class of 
Difibsion results is by taking a porous earthenware cup, 
thro<l^hpo^oul Q (L, ^iff, 68, such as is used in Grove's voltaic 
**"■ battery, drying it perfectly, and cementing into 
its mouth an open glass tube, 6, three quarters of an inch 
in diameter, and a foot or more long. A wide-moutlied bot- 
tle, c c, being placed aa a temporar)' cover over the porous 
cup, it m-iy be filled witli hydrogen gas by displacement ; 
and if the end of the glass tube be put into water contained 
in a rcsenoir, d^ the water will rusli up the moment the 
bottle is removcfL Wlien this motion is completed, if a jar 
of hydrogen be held over the porous cup, the water will be 
driven down with great rapidity, and a number of air-bub- 
bles quickly escnpe. The extrnordinary sjiccd with which 
a gas will flow in and out of pores coidd not bo better dis- 
played. This rapidity of motion is an clement with which Dm!!5.,7rihk.«g)i 
the jjhysiologist has to deal, as we shall presently hnd. «ni)M)*Mt 

Kvcn when the texture of the substance is much closer, and the pores 

niffoirion of extreme minuteness, similar results can be obtained, as was 

iliroutili In- shown in tlic experiments of Dr. Mitchell, of Philadcljihia, who 

employed thin sheets of India-rubber. If^ over the mouth of 






I 



I 



I 



DiffUtao ttuvngh IndlK-robtcr. 



PASSAGE or OASES THBOUOH POEOrS FILMS. 

jjass bottle, such a thin tissue be tightly tied, and the bottle placed 
in an atmosphere of carbonic acid gas, movement at once takes place, a 
little air flowing out of the bottle into the carbonic acid, and so large a 
pfyio. quantity of ihe acid passing the opposite way 

that the India-rubber soon swclU outward, 
and eventually caps the bottle like a dome, as 

, , ^^^^mn *" '^^' ^^* *' ^* *^' if the conditions be ro- 

Df I ^^^^Vl versed, the bottle being iillcd witit carbonic 
acid, and then exposed to the atmoflpiierc, the 
India-rubber will be deprcs3cd, aa at a, and 
stretch so aa almost to sink to the bottom. 
Such experimcnta therefore prove that, even 
though borriera of a very close texture should 
intcncne, gases will puss tlu-ougli them, and 
with BO much force, as Dr. ilitciicll sliowcd, that many inches of mercury 
may be liAed, nor does the movement cease untd the gasea on both sides 
of the membrane have the same composition. 

Other substances having a close texture may be thas readily pennea- 
tcd. I found that a little bladder of shellac, blown on Iho Experimrnu 
end of a ghifis tube, permitted the passage of the vapor aris- J^/jJ'^'^]^,^ 

ins: from water of ammonia. The "id*, 
instantaneousncss of these motions is, how- 
ever, most beautifully illustrated by employ- 
ing soap-bubbles, the liquid nature of which 
excludes the idea of pores in the strict accepta- 
tion of that term. If a bottle, a rt, J^i</. UK be 
rinsed out with ammonia, and then, liy means 
of a piece of glass tube, 6 i, a aoajj-bubble, tr, 
bo blown therein, the air from the bubble be- 
ing immediately drawn into t!ic mouth with- 
out a monicnt's delay, tho strong ttiste of tlie 
ammonia is perceived. Or if a rod, dipped in 
hydrochloric acid, be presented to tho projecting end of the glass tube, 
copious wliite fumes Hrise. Tliis therefore shows tliat vapors will pass 
through barriers having no proper pores, the transit taking place instan- 
taneously. 

Soap films enable us to demonstrate the cndosmosis of gases in a very 
advantageous manner, owing to their cohcsivencss and tbiimess. If the 
finger be dipped in soap-water, and then rapidly passed over tlic mouth 
of an empty bottle, so as to leave a horizontal film attaclied across, on 
exposing the bottle to carbonic acid gas, the horizontality of tlie film is 
immediately disturbed, and it soon swells up into an almost spherical 
dome. Or if tho bottle be filled with carbonic acid, and then exposed 



Fg. TiX 




;e of ffUf 



^ uomc. I 

mk. 



154 



PASS-VQE OF OASES THROUOn POBOt'S HULS. 



to tlic air, the iUm is promptly depressed Into a deep concavity, and 
bursts. By these inethodti the passage of all kinds of vttjKtrs and gas« 
may be demonstrated, oxygen, hydrogen, carbonic acid, protoxide of ni- 
trogen, the vapors of peppermint, Invcjidcr, and various essential oik 

By many experiments on such dit^erent subataoces, 1 found that the 
Uwofw uiiii^ '*^ ^^ equilibrium fnr gusea and vapors is ibe same as for 
liuin, an>i ex- liquids. No matter U'liat the thickness or thinness ofapo- 
ttiupeio 1^ ^^jg barrier may be» movement takes plaec through it, un- 
til the media on its opposite stiles havo the same chemical composition. 
The observed action, in jjartlcular cases, will tliereforo altogether dcpesd 
on the cirnimstonces under which the experiment is made, A fiO^>-bab- 
blc fall of carbonic acid, exposed to the oir in a closed bottle, coUi^acs 
only to a certain extent, when the prccntagc constitution of the air it 
contains is tbc same as that of the air in the bottle, contaminated witli 
the carbonic acid wlueli the bubble has yielded it. But if the babblebe 
exposed to the free atmosphere, it collapses almost completely, for now 
the carbonic acid escapes tinolly away. 

One of tho most interesting facts connected with these results is the 
Ai-tio throu-h 1*^^*-'*^' manner in which a film of excessive tenuity willdi»- 
ninu uf ex- charge these mechanical functions. With a litllc care, a 
rsnic Ml y. j^j^^ ^j^^. 1^ obtained so thin as to be invisible except in, 
certain lights, when it presents a velvety black asiK?ct, In this condi- 
tion, as Newton has proved, it is not thicker than three eightlis oi'a 
millionth of an inch, yet endosmosis takes place perfectly throngh it: it 
ex[>unds and collapses, rises up into a dome, or is depressed into a eoti- 
cavity, an the circumstances of its exposure may 1h% And tliis sbould 
prepare uh to admit that in organic tissues of tho utmost degree of tenu- 
ity these physicid jihenomena may occur, and tliat even under these most 
uidikcly circumatances such tissues may give origin to mechanical forces 
of the greatest intensity, as we shall now prove, 

Graham's law of tho diifusion of gases has but a very limlteil physio* 
Inapi.licabiliiy ^^^P*^ applicjition. The introduction of it in eases to which 
i>r(iraiiam'« it (locs not pro|>eTly apply has led to several errors. There 
'^^' 13 nothing common in tlio result of the movement of gases 

exposed freely to one another, and exposed with the intrr^-ejition of a 
close-pored tissue. The tissue itself gives origin to mechanical fopoe of 
ancli intensity as not only to modify tlio diffasion rate, but, in a groat 
many of the most important uises, absolutely to invert the direction of 
the motion. Thus, tlirough a stucco plug, in which the porej are of 
sensible size, atmospheric air passes more rapidly to carbonic acid than 
carbonic acid does to it, but through the thinnest tilra of water just tlic 
reverse takes place, A bnbblc full of that acid, exposed to the air, lets 
it escape with so much rapidity that in a few moments a complete col- 



FORCE OP PASSAGE TKKOrGII MEltBRAXEB. 



153 



lapso lias occurred. If the law of diffusion Iicns Iii'ld good, tlie babble 
•bould mpidly dUleml. 

Jloist mcnil»rancs nnd films of water, by reason of their chemical affin- 
ity for gascoas substances, nnd their consequent condensing (<onOenBinc»c- 
acbon, become the origin of great mccimnical power. Under tiwi «f mwii- 
mnA oonditiond, I have seen carbonic acid pass into atmos- "**' 
pheric air, driven, as it were* by the fiction of the membrane against a 
presatirc of ten atmospheres, and sulphurcted hydrogen against a pres- 
sore of twenty-five atmosphc-rcs, and, even against these great resistances, 
tlie passage is accomplished with so mucli promptness as to lead to the 
inference that a membrane will cause otic gas to diifusc into another, even 
Uioogh the apparent resistance be indefinitely gi-cat. 
Fif.'t. In J^fff. 71 is given a representation of tlie arrangement by 

which these results were obtained. It consists of a strong 
glass tube, seven incites or more in length and lialf an inch in 
diameter, hcmieticaUy closed at one end, tlirough which a pair 
of platina wires, ft, f, \yasB into the interior of the tube jiar Jlel 
but not toudiing. The other end, a «, has a bp or rim tunuH,! 
on it. Bet^vceri the platina wires, a gauge-tube, </, is dropped, 
to show the amount of condcnsalion. On the top of the gimge- 
tube a small tcst-1u!ic,^. is placed, to contain a reagent suited 
to the gas under trial, as lime-water for carbonic acid, acetate 
of lead for sulphureted hydrop-n, litiims-water for sulphurous 
acid. Sometimes, instead of this test-tube, a piece of paper, 
soaked in the proper reagent, was employed- The Mflmmraofiha 
large tube was then filled witli water to the height fon-oofinni- 
C e. Its lip or rim, a a, being next smciux^d with 
bomt India-rubber, to insure absolute freedom from leakage, 
a tliin siiect ot* India-rubber was tied tightly over it, and over 
tliis again, to give strength, a very stout piece of silk. Kvery 
thing being thus arranged, tlie projecting wires, i. c, were connected with 
a voltaic pile, decomposition of the water ensued, oxygen and hydrogen 
being disengaged, and a condensed mixture of atmospheric air and tlioso 
gaaes accumulated in the space a a e e, the gange-tubc showing the ex- 
tent to which the condensation !iad gone. Now if the little tube,^, had 
been filled previously with lime-water, and the wliolc ammgcment was 
introduced into a jar of carlxinlc acid gas, the upper part of the lime- 
water presently became milky, and after a time a copious prccipitato of 
carixmatc of Lime subsided. Tliis would reacUly take' place when the 
gm^ was indicating a pressure of ten atmospheres. In like maimer, 
wfaen a piece of paper imbued with carbonate of lead had been introduced 
into tlie tube, and a pressure of 24| atmospheres accumulated, on intro- 
ducing the Lustrumeut into a vessel of sulphurcted hydrogen, the paper 






156 GSsnsuAL pmNciru: of diffusiox. 

quickly became browiu So sulphuretcd hydrogen can pass through ft 
sheet of India-rubber and diffuse into an atmosphere of oxygen, hvdirj- 
gen, and atmospheric air beyond, though it is resisted by a pres&nxc eqnil 
to that of 800 loot of water. 

The method of condensation here employed, because of its freedom Jrom 
mechanical concussions, enabled me to continue these researches up to 
pressures of 50 atmospheres without leakage, in comparatively Mender 
tulies, and even under these circumstances gaseous dillUsiou Hcemcd to 
take place without any rcstrauit. 

It wotUd lead rao too far from my pri'sent object to pursue the eon- 
Genoral tact* ^idcration of these facts, and I must therefore be content to 
^mmtrrtiHi wub refer the reader to the memoirs in whicli they have been spo* 
QuuMi. cinlly discussed.* It is sufiicieiit to understand, IsL Tlurt 

ga^es simply exposed to eacli other intcr-diffuso with great rapidity, and 
at a rate inversely proportioned to the square root of their densities ; 2i 
That the same takes place through stuccn plugs, or diaplmigms with open 
jH)rc3 ; 3d. That a gas dissolved in a liquid, or held in a condensed state 
by a solid mass, will exchange by inter-diffusion with any atmospfaere 
to which it may bo exposed, in these cases the liquid or the solid mass 
becoming a source of force : 4th. That through a liquid, which, of coaree, 
has no pores, gases arranged ou its opposite sides will diffuse, but ^t^ 
rate is no longer exjire^scd by Graliam's law; .5th. That a liquid hold- 
ing a gas in solution pcmiits it to diffuse with another gas held by lO- 
othcr liquid in solution. 

On tlie first of these principles, the iVcsIi air of the bronchial tubes ex- 
changes with the respired air of tlic pulnionar}^ cells, the case being that 
of a gas exposed to a gas. On the tliir<l of tliese principles, arterialiKa- 
tion of the blood takes place, the case beuig tliat of a dissolved gas cx- 
clianging with a free gas ; and on the fifth of these principles, aquatic or 
gill respiration depends, the case l>cing that of a di.-'solved gas exchang- 
ing witli another dissolved gas. 

Under its simplest aspect, the act of breathing consists in tlic elimlna- 
Twion* form ^^^^ ^*'" ^-''^bouic scid froiu the system, and the introduction 
of no|>inttQr}' of oxygen. The manner in which the respiratory saj&ce 
iiierinumm. f^Qcs itself from the former, and secures new supplies of the 
latter, differs very greatly. In the lower orders which lead an aquatic 
life, currents arc cstabhshed in the water by the aid of ciliary motion, and 
by tliese the necessary changes arc made. In others, in which respira- 
tion is conducted by the skin, incessant locomotion is relied on; and 
again, in otliers, the water is drawn into the stumach and intestinal ctuud, 
and every part bathed with the aerating medium. 

In insects, the type of carrj'ing air to the blood is developed to the ut- 
* AiuoricAn Journal of Mcdicol Sciences, Mar, 1838. 



^ 



BESFIIUTION OF IKSBCTS AKD HSUES. 



167 



moat degieCt ttcrc bcinj great numbers of tracheal tuljes pcnading all 
the soft parts. These occaaioually prcaent dilatations, acting as reser- 
Tcurs — tlio tbresluulowing of tho respirator)' cavities of the higher tribes. 
Of such, Fiff. 72, representing the air-sacs or tracheal dilatations of the 



\m 



11 



JUr-»ei of ltwMt& 



Bpt rftclcof In locL 



liortoram, is an illustration. The tracheal tubes Rw,pirajion of 
Dtnunicate with the cxtei-nal air through openings which '"»»«»»■ 
niajbe obslmctwd by a valvular arrangrnicnt, as represented in^i^?. 73. 
The photograph tirom whicli tliis iigure was taken shows sucli a Fpiracle 
magnified 75 diameters. Tliese organs may be seen arranged in rows 
on c*ch side of the body ; thus, in the eotnmon caterpillar, there arc ten 
pairs. The mode of guarding the orifice %'aric3 in different cases, somc- 
txmcB tofts of hair being resorted to, and sometimes, as in tho Hgoic, 
Ives. 

true lung is first recognized in the swimming bladder of fishes as 
n^niple sael In t!ie car]>. the tendency to a multi-ehanibcred coiistruc- 
tioa aJready appears under the form of two such bladders, a, b^ conimuni- 
'V**- ^ eating with each oth- 

er througli a narrow 
tube. These are oon- 
nectwlwithtlicoesopli- 
agua, £», by means of 
the pijie c d^ tho Hah 
being tlins enabled to 
reniove at pleasnTo a part of the air contained in the sacs by muscular 
compression. Though this mechanism is, as we hare said, a radiment- 
arj- lung, it does not properly subserve the duty of such an organ, but is 
employed for producing variations in tlie spccitic gravity of the animal 
by compression or rarcthction of the included air. In these Rrt,,ir»iion of 
tribes the gilU arc the mechanism for aeration, which is ao '^>'"^' 



Alr-«ae af Cib. 



158 



liESPIUATlON OF FI8UES AND HEPTILES. 



FtaJX 



cotnplishcd in the following manner: The mouth is periodically filled 
with water, which is driven ]>ast the gills by muscular compression* and 
tljeroby tl»e carbonic acid is removed from the blood which circulntcs in 
those organs, and oxygen is obtainwl in return. For this reason, a tUli 
dies vcTj- quickly when its mouth is kept open. The angler knows that 
it is not owing to any \o»s of blood, nor to any injurious lesion tltut tlii: 
hook may cause but simply to suffocation, the water no longer lifting the 
gill covers, but merely passing out through the oj^cn mouth. 

The experiments of Humboldt and l*rnvcn9al clearly demonstrate tlw 
nnalog)' between aquatic and aerial red])in)tions; for water is not de- 
composed by the breathing of fishes : it is the air dissolved in it that is 
used. In the pampio examined by tlie.«e chemista, there waa 20.3 per 
rent, of its volume of air, consisting of oxygen 29.8, nitrogen 66.2, awl 
carbonic acid 4.0, m the hundrctl parts. After the fishes Irnd remained 
in it for a due time, it still contained 17.6 per cent, of its volume of air, 
but this in 100 parts now consisted of oxygen 2.3, nitrogen C3.9, and 
cirlwnic acid IVXS, There liud therefore lieon a consumption of oxygca 
and evolution of carbonic ncid, together wilh a slight removal of nitrogen, 
this Ixtirig the general result v.ime33ed in aerial respiration. In a sim- 
ilar cour?o of experiments on the livalhing of gold ti^liea, 
made by myself, the result corresjwnds to the preceding 

itemcnt, only the water T used was richer tn oxygen gas, 
nd tlio trani^position into carbonic acid did not seem by 
any means to be so complete. I abo remarked the same 
diminution in the quantity of nitrogen, but am dlB|H)8ed to 
attrilmte it not so much to the consumption of tlsat gas by 
the fishes as to its diffusion fi*om the water into the atino- 
gphcro, the solvent power having clianged by the substVn- 
tion of ciu-lwnie acid for oxygen- 

In reptiles the lung presents the sac-like form, as in P'iff. 
Rmplnition of 75, a ]}uIinonary artery passing on one side, 
npuios. „j,(| ^ jnihnonary vein returning on the otiicr: 

a is the traclica; 6, its bifurcation; e, pidmonary artery; 
rfi flf, pulmonary vein. It often occurs tli^t the two lungs 
arc not equally developed, one of them, Tt, being rudiment- 
ary as compared with the other, .\. Into such a sac in scr- 
jx^nts the air is forced by muscular contraction, a kind of 
swallowing. It is ex|»clled from them by the contraction 
of the nlxlominal muscles, and hence the hissing sound 
which it emits daring its expulsion. From the simple 8f.c 
to the cellular lung the advance is made by degrees, a de- 
velopment nf parietal cells upon the inner surface taking 
place. At the intermediate stage, between the simple sac Uiag of rri^tua. 



BTBCCTLTIE OF TUE LfNOS. 



159 




l.aog« of mao. 



the btghl)' subdivldccl rcspinitoiy organ of tho mnmmab, tho condi- 
tion of things is well iUustrated by the lungs 
of tho frog. In Fi^. 70, a ia the liyoitl appa- 
ratus; h, cortilA^nous ring at the root of the 
lungs ; c, the pulmonary vcssela ; and (/, (/, tho 
pulmonar}' sacs. 

Of all tril)e3, tho respiratory mcchanisni \i 

most higlily dcvelo^wd in birds, Bcfpimtion at 

which, besides being provided with '''^■ 

lungs, have nir-sacs between the muscles, and 

rcspiratorj' membranes spread on tiic interior 

of the hollow bones. It is in consequence of 

I « -^^npiggg^ip^ tjiig (i,;it a bird is killed so readily, even by a 

^^^ Lngttfftvtf. very email shot, since it is scarcely possible to 

^^pe a perforation into any part of the body without opening the rcspi- 

TEtory cavity. 

In man, the broncliial tulje, as it passes into each lung, brandies forth 
like a tree, the walls of the tubelets thus arising having car- 
tilaginous rings to preserve their form under compression, 
drcuUr organic muscular fibres to enable them to contract, and lon^tn- 
gitnclinal fjtsces of elastic tissue to shorten them after extension. In 
their iuterior (hey are covered willi mucous membrane j)rovided with 
cilia. When the proper degree of minuteness, about ^ of an inch, ia 
reached, they consist alone of clastic membrane, interspersed with mus- 
cular fibres, and upon their sides the air-cells open ; sometimes single 
«mC!A, or sometimes many cells communicating witli one another, discharge 
ihitragh tlic same orifice, the tulM.'let itself ending in a cell. The air- 
R!U« have various dimensions, from -^ to yj^ of an inch. Their struc- 
larc ia like xhaX of tho (ubelet. The pulmonar\' capillaries are spread 
to closely npon them that the spaces between them are leas than their 
own tltamcters, whicli, on an average, arc ^^inr °^ '^ inch. As the cells 
Hm| dose. ti>};cther, the blood-vessels passing between thorn are brought 
^^BBOmmuitieation with the air on both sidc^, and arterialization is thus 
rapidly and completely performed. Each tubelet, with tho air-cells thus 
cinattfod npon it, is a mininlure representation of the lung of a reptile. 
Thew cells tliomaolvesi communicate by Literal ajwrturcs with one an- 
other. Tlic membrane which lines their interior is sharply folded at the 
apcrtvrcft) and there arc reasons for supposing that it contains organic 
mgflBtthr fibres. It is stated that each terminal bronchus has nearly 
20.000 ftir-ceUs clustcrwl npon il, and tliat the total number is 600 
milliona. 

The mode of distribution of the air-tubes is represented in ^iy, 77. 
a is Ihe Uryns j b 6, the trachea, tVie upper letter corresiK)nding to the 



160 



STRL'CTCRE OF THE LUXGS. 



cricoM cnrtilftgo; f, the left bronclias ; (7, tlic right broDcbas ; «,j^^.it8 
ram ifi cat ions in the right Inng^jJ; A, t» ramifications of the left bron- 
chus in the left lung, i* k. 




IIUIIMTI A^.tUbtA 



Tlut lioul «ad Inti^ft. 



J^iff. 78, arningcincnt of the heart and lungs, the latter in port section. 
1, left anricle of the heart; 2, right auricle; 3, left ventricle; 4, ri^it 
TcntTicle; 5, pulmonary artery ; 6, aorta; 7, superior vena cava; S,in- 
roniii)ata; 9, Ii*ft primitive carotid; 10, left subclaYian, ; 11, 12, upper 
rings of trachea and c-artilagoa of tlio larynx; 13, nppcr lobo of right 
lung; 14, upper lole o!*Icft lirng; 15, right pulmonair orteiy; 16, 16» 
lower lobes of lungs. 

J^^iff, 79 illustrates the manner ti 
distribution of blood-vessels OQ, 



Fifi 19. 



air-cells of the lunjrs. 



m 



Aa the blood to bo arterialised 
passes through the puhnoriary capil- 
laries, its discs can only move in eia' 
gic files, and even then prolwbly un- 
dergo a compression which cJmngcs 
their form. As soon, however, as 
they escape into the larger vessels, 
their elasticity enables them to recov- 
»iMrii»u«.or«.piiuri«..n M.^.N..fib,h,n».^ er tlieir original shnpe. 

By the aid of this ehiborately congtrueted mechanism tlie air is brought 

ThimitARMiii ^'^ *'*^ blood. There are three distinct stages through whidt 

ihfl introduo it has to ]>asa. The first is tlic filling of the trachea and 

larger rami6ealions of t lie bronchial tubes: this is acoom- 

plifhc 1 by atmospheric pressure, brouglit ijito play by muscular contT*> 



J 



MOVEMENTa OP EESTinATION. 



F^ «X 



The second stage U the translation oftlio frcsli air from tlie latter 
Iiial lubea to tlie ultimate nir-cells: this is accomplished on the 
jiK; of gaseous dlifusion. The tliird stage is the passage from the 
lU into the blood : this is through the wall of the cell, the wall of 
ilood-vessci, and the sac of tlic blood disc; it involves ]Ki8sagc 
gh mejnbrancs, and implies thi-ir condensing action. KucU of ibuso 
stages we have now to consider. 

: The introduction of fresh air into the trachea and larger ramifi- 
ks of the bronchial tubes is accomplislicd hy muscular Tiipeff^iofHf 
iction, whicli calU into operation ulniospheric pressure. rrrMun) of iho 

'' i-espiration the diaphragm is nearly sufficient for *"' 
■ [^ This musclr, forming the convex floor of the chest, as soon 

contracts, assumes more ne-arly a plane fignrc, thereby increasing 
intent of that cavity; and, just as in a common bellows, when the 
boacrd U depressed, the air tiows in tlirough the pipe, so, on the de- 
of llio diajdiragm, the air Bows in through the trachea, forced by 
ctcnml pressure 

An e?cpcrimcntal illustration of the manner in 
which the air is introduced into the cavity of the 
lungs by the descent of the floor of the chest, 
and llicn exjK'lIcd hy its elevation, is represented 
in J''i(/. 80, in which a a is a tube of glass half 
an iiicli or more in diameter, and six or eight 
inches long, to the lower end of which a blad- 
der, A, is tightly attached. The tube is passed 
through the neck of a bell-jar, c t\ air tight. A 
large glass reservoir of water, filled to the height 
(/ </, receives the bell-jar, as shown in the tigure. 
When the jar is depressed in the water the air 
is ex|Kllcd from the bladder, and when iJie jar 
is raided the air flows in. By nltcmately ele- 
vating and depressing the bell, the bladder exe- 
cutes movements like those of the lungs, of which, 
indeed, it is a repreficntation; the glass tube be- 
ing the trachea, the bell-jar the walla of the chest, 
and the rising and falling water-level the rising 
Tn tliis illustration the bladder is, of course, pcr- 
passivcos was at one time supposed to be the ease with the lunga : 
roncous opinion, which will jmisently be corrected 
the matnrc porio<l of life, and esiiccially in deep rcspirntion, the ac- 
f the diaphra^rm is insufficient for the introduction of air, 5[,„„„^|^ 
•till farlhrr vohime is obtained hy raising the ribs, which tmdurfng th« 
kscs llic dimensions of Ihe chest from right to left, and 

L 



h 




dling diajihragm. 



162 



liOVEUEKTS OP BESPUIATIOK. 



also (torn front to back. In men, this cffcK:!t takos place more patticTiki- 
\y through lite movemcnta of the lowi-r ribs, anU tliis tbnn of redpindoa 
is therefore sometimes called the mfcrior-costAl ; but in women the npper 
ribs arc more movable., the dilatation of the chest is there greater, and 
the respiration thercforu designated as the 8u|)erior-costaL In theac 
movements of the ribs, and especially in violent respiration, many mus- 
cles are involved. 

In the reverse act, that is, in expiration, or the expulsion of air throngli 
the trachea, the floor of the cheat is raised. The diaphragm, when it 
contracted, made pre55nre npon the viscera of tlic abdomen, and foireii 
the muscular walls of that caWtj- outward ; but, as soon as the diaphrsgrn 
relaxes, tlie abdominal muscles contract, and thus an antagonizing force 
is originated wliich tends to ex|»el the nir. In this the elasticity of the 
lungs and of the walls of the tliorax itself aifcrds a great assistance. 
Owing to tliis elasticity, the muscular exertion required for the inlrodno 
tion of the air greatly exceeds that reqiurc>rl for its expulsion. 

In tranquil rcsj»iration, wc may regard the changing of iho air to be 
acconiplislicd by the alternate depression and elevation of the dlaphr^ 
matic floor of the chest. <.^n an average, this takes place 17 times in a 
minute^ and in an adult of llie standard size wc may assume that 17 
cubic inches of air are introdnccd at each inspiration. Of every fivr 
brcatlis one is iisnally deeper than the other four. The statement oftra 
made, that Ave pulsations correspond to one respiration, must be received 
with a certain restriction. In pneumonia, the respirations may be to 
the pulsations as 1 to 2 ; in typlioid fevers^ as 1 to 8 ; and even in a 
state of health tlicrc m.iy be considerable variations. 

ily muscular movements, which thus call into action atmospheric plea- 
sure, the air is drawn, but not forced, into the respiratory apparatuit. 
Considering, however, Uio Boli<l contents of the lungs, which can not be 
taken at less tlian 200 cubic inches, it is clear that the amount is not 
more than sufficient to All the nasal jiassages, the trachea, and tbc larger 
ramifications of the broncliial tultes. Lying nearest to the ontlct, it 
would be the first to be expelled by tlic act of expiration. There could 
be no exchange of the fresh for the foul air, nnless some additional means 
were employed for acconiplishini; its transferuni-e from the larger ramifi- 
cations of the bronchiid tubes to the remotest air-cells. 

2d. The transference of fresh air to the cells is accomplished by re- 
sorting to two different principles, the difiusion of free gases into one an- 
other, and musctUar contraction. 

An estimate of the relative share which each of these takes is ftrrivt>d 
Effect (rf Kaso- at by an examination of the absolute velocity with which 
ui^oforl^lik S^^^ ditfusc into one another. The statement that gases 
muscle fibres, act as vaciui to cach other has led to some very crroncoos 



TsaaUWB<OP OXTOEIT TO TBB BLOOD. 



163 



ions. It has been taken for granted tiiat tlie actunl diffusion is 
pid, perhaps npproacliing to the velocity with which gases rash 
a void. Bat I have shown* that this is altogetlier a misconception, 
d that the transit of tresh air trom the bronchi, exchanging with foul 
from the ceils, if conducted on that principle alone, would require a 
riod greatly beyond the time occupied for one respiratory act, which ia 
cmt throe seconds and a halt'. 

To an additional agent we must tlierefore look for a complete explana- 
and this, I think, is presented in the circular organic libres of the 
onchial tabes and cells. It has long been understood tliat these pos- 
w the power of varying the capacity of the tubes. 
With this agency in \'icw, this second stage of the process is acconi- 
ifaetl as t'uUows : Tlie carbonic acid, vapor of water, and excess of m- 
if any, tliat have accumulated in the cells belonjp'ng to any given 
mchiul tree, arc exjx'.Ued therf^fnjni by tlie inuseular contraction of the 
[culaj organic fibres, and are delivered into the lai^^ bronchial tubes, 
which diffusion at once takes place with the air just introduced. As 
in as the expiration is completed, relaxation of the muscular fibres oc- 
and the passages and cells dilating, both through their own elastic- 
and the exhaustive effect arising from the simultaneous contraction of 
bronchial trees, fresh air is drawn into them, the alternate expulsion 
ixitrodaclion being accomplished by muscular contraction and elas- 
ty, the ditferent broncliial trees coming into action at different periods 
lime, some being contracting while others are dilating. 
3d. The third stage is thcpassage of oxygen from the cells to the blood: 
is through tJic wall of tlie cell, the wall of the blood-vesecl, Vmmak« or ox- 
Md the sac of the blood disc The carl»nic acid issues from 'Jh^*°^n>UMOM 
le plasma, and passes through the wall of the blood-vessel loUwtlood. 
id the wall of the celL 

Many physiologists have supposed that this exchange of oxygen for 
rbonic acid takes place on the principle of diffusion. On Ex,h»nCT t>f 
B antliority of Valentin and Brunncr, it has been assertetl mrboidc; acu 
■t the projKirtional exchange actually observed is 1174 of '*'*'*>^™- 
Eygtfii for U"MX> of carbonic acid, these being the theoretical quantities 
oder tlw law of diffusion ; but there is no difiicolty in proving lliat lliaS 
i a phy8i<'al impojisihility, for the exchange is not merely tlmt of oxy- 
bn and carltontu acid ; it is much more complicated. The lungs regu- 
tte tilt) quantity of free nitrogen in the system, and there is a constant 
•cape of the ^-ajtor of water. Tliese bodies, morfover, arc not prescnt- 
i in the gaseous state, but in that of liquid solution; and the wall of 
cell, of the palmonary capillary, and of the blood disc, by their con- 
Cnstng action, totally disturb the conditions of diflfiision. 
• AmencsD Joomal of Med. Science*, Ajiril, ISJ2. 



164 



EBCAPE OP CAIUSONIC ACID FROV. THE BLOOD. 



If an aqncous iilin, not more than throe eighths of a mtllionth of an incb 
in tliickness, can coiupletely disturb the law of diflasion Ijv the cuinJniv 
ing action it exerts on carLouiu acid and oxygen, wliat may bo expected 
from the moist walls of the nir-rcUs and pulmonary artcTTk', whiclx oon- 
jotiitly must be more than a thousand times as thick? 

Ffom these complications, it is not possible to assign any definite ratio 
fiS expressing the gaseous exchange between the interior of the odls 
the blood, for, so far firom this being a case of exchange bi'twcen two 
es without any obetniction intervening, the condition under which alone 
the law of diffusion applica, the nitropcn is doubtless in a elate of wJa- 
tion in the bloud, the steam in tlic liquid comlition of water; and r- 
spocting the carbonic acid, nothing cciiuin is known whether it be in m- 
lution or chemically combined. Perhaps it is united with t;o(U in ibe 
blootl as a bi-carbonate. l-'rom tliis latter substance hydrogen gas will 
espcl one half of its carbonic acid, and in like manner a stream of by 
drogen gas passed through blood deprived of its fibrin removes carbonic 
acid. Upon such principles it has been supposed that atmospheric oxj- 
gcn removes carbonic acid from the blood during respiration, just as woulii 
a slream of hydrogen remove half tho acid from a solution of bi-carbon* 
ate of soda. 

The generation of carbonic acid in tho system is commonly localised 
p. ^^^^ by referring it to the soft tissues. But, though doubtless 
BOMraiion vt much originates in this way, as is illustrated by tlic case of 
*"^'*^ * ' insects, in which the air is carried directly to the parenchyma 
of tlic organs wiliiout the intervention of any proper oxidizing blood, 
there can be no doubt that in muii, as in ail the liigher tribes, a ^Txy 
Large projiortion is generated in the blood itself. It' there were no other 
reason to bring us to this conclusion, it would Ijc sullicicnt to recall that 
ultimate oxidation by no means occurs at once, but that the rarlons 
wasted products pass from stage to stage in their retrograde career. 
Thus, between the syntonin of muscular tibrc and the urea of the orinc, 
many stops or stages intcr\"cne, and that much of these changes is ac- 
complished iu tlic blood itself is demonstrated by what occurs in the 
use of excesses of starcli, albumen, or gelatine in the food. Such sab- 
stances, finding access through tlie absorbents in a modified form, but not 
wante*l for the repair of aixy part, are dismissed without ever entering 
into tho composition of any organ, by tho lungs or the kidneys as prod- 
nets of oxidation or derivatives thcrcof- 

The act of respiration in man is therefore accomplished in the foliow- 
Gvncnl stAto- ing way. The air, introduced by atmospheric pressure, 
pivNM of n»- brought into play by the action of the diaphragm and other 
plraiton. respirator}' muscles, fills the nasal passages, the trachea, and 

larger ramifications of the bronchial tubes. Between it and the gas 




OnXECAL PrATCMEIfT OP THE REBPICATORT ACT. 

ning from the pnlmonnry vesicles, diflftieion steadily takes place, tend- 
to remove tlio cell gas into the atmosphere; but this gas is not 
»ught from the vesicles by diffusion alone, which could not act ivitli 
Scicnt speed, but by the contraction of the circxilar organic muscles of 
|ie bn^nchiaJ tubelcts and of tlic eclls the different bronchial trees not 
Cting eiraultaneously, but successively. As soon as contraction ia over, 
'the tabes expand by their clastidty, and tlie air is drawn into the cells, 
earh bronchial tree, by its contraction, aiding the cxi>ansion of tlic adja- 
crnt oncH. The lungs ore- therefore not altogether passive during respi- 
ration, us is sometimes said. The exchange between the gas in the cclla 
and that in the blood does not take phicc through simple diffusion, or in 

Fititi<*a proportional to the ditfusion volumes of oxygen and carlwnic 
It is a comple-x diffusion, in which the disturbances arise from the 
gnAes in the blood being either dissolved or combined, and througli scv- 
intcrvening membranes, tliat of the air-cells, that of tlie pulmonary 
tery, and that of the blood disc, all of which exert a condensing action, 
'the result of which it is impossible tn furnish any numerical estimate, 
be process ends by the expidsion of the foul air wliicli has accumulated 
the larger bronchi and trachea, by the diminution which takes place 
; the capacity of the chest during expiration, occasioned by the contrac- 
of the expiratory muscles, the elasticity of the walla of the chest, 
of the lungs themselves. 
Such is the arrangement by which fresh air is ronstantly presented to 
tbJood, and the gases and vapors exhaling from it arc removed. The 
of exhaustion occurring in the chest scarcely juslirics the cx- 
»ion sometimes used, **a tendency to a vacuum,'* since it is rarely 
t than competent to raise watcT a single inch. This may be reailily 
by dipping a glass tube, 0|>en at both ends, and half an inch in 
eter, into a cup of water, an<l placing the ]>rojecting extremity bc- 
i the lips, taking care to keep the muscles of the mouth at complete 
at. It will then be seen tliat at each inspiration the water rises about 
inch, and at each c-xpiration is depressed to a Rimilar extent. Its 
noveim'nls indicate the degree of rarefaction or compression occumng in 
ctiest. 
It bas been found convenient to consider the gaseous contents of the 
totigs under sevcnd different titles: l.st. The residual air is Divifttoiuor 
ibat portion which cm not be removed by tlie roost power- ^S^f'jho 
expiration; 2d. The supplemental air remains after tran- iMtg*. 
Ill rc^nratinn. but can be removed at will ; 3d. The breathing or tidal 
' is that portion which changes by tranquil inspiration and exjjiration ; 
th. The complcmcntal air is that which can be inhaled by the deepest 
^i«piration, over and above that introduced by ordinary breathing. 
rbesc are terms introduced by ilr. Jcfireys. 



166 



VOLUME AND CIIAXGES OP THE QAS. 



*♦ The amount of nir that can be expelled by the deepest expiration 
CoDDKtJon be- after the fullest iiiiijilnition*^ bears a singular rehuion to ibr 
KTaad *'^^ he%ht of the individual, as was discovered by Dr. Hutch- 
lieitfht- inson. ** For every inch of stature from ti\-c to six fevi, 

ciglit additional cubic inches of air at tJO^ Fabr. may be thu« given onC 
The quantity of air which can be thus expelled for the stature of fivefwl 
one inch is 174 cubic inches, and for six tcet, 262. It is independent of 
the absolute cajiacity of tlic chest. 

The diurnal amount of air introduced into the lungs has been ^'arioofly 
_ , . cstiinatcil from 226 to 309 cubic feet. A part, from 4 to ti 

Tolomc and , . , , V^ . 

chufCM of the per cent, of the oxygen thus uitroduced diBappeus in tbe 
i«qtlr«d e^ lungs, and the expired air is cha^d with from 3 to d per 
cent, of carbonic acid. But tlint nothing analogous to combustion ocean 
in those organs is proved by their tcnii>eralurc which is not higher thim 
that of other parts of the system. Moreover, carbonic acid can bo with- 
drawn from venous blood in a Torricellian vacuum, and still better by 
agitating the blood witli such gases as hydrogen and nitrogen, proving 
that llmt gas prtMJxiats in the venous blood before its entry into the 
longs, and is not fanned in those organs, unless, indeed, it exists as a bi- 
carbonate, as already mentioned. The quantity of carbonic acid thas 
diseitgaged is less than the quantity of oxygen absorbed, becaufio much 
of the latter is consumed in the production of sulpliuric and phosphoric 
acids, which escape in the urinary secretion, as indeed docs a large qiutii* 
tity of carbonic acid itself. 

The experiments of V'icrordt show that the expiration, iti a state of 
Vi«wii'« rest, contains 4.334 ]X'r cent of carbonic acid ; that, as the 
•jcptjimenu. numbcr of respirations per minute increases, the pcrccnti^ 
amount of carbonic acid diminishes ; ond tluit for every expiration, with- 
out reference to its duration, there is a constant amount of carbonic add, 
namely, 2.5 per cent., to which we must add a second value, cxpressii^ 
tiio quantity of carbonic acid, and which is exactly proportional to the 
duration of the respiration, as is shown in the following table. 



RrqitratloM 
por luLnntc. 


urboDlc Httl. 


CuaOABUk 


Aa|iiu>«itattno of tlw pcrcMttWM 
of Ilie txTbonle acVl tot tarn 
diirath'ti of tlui naplratlan. 


a 

12 
24 
48 

W 


&.7 
4.1 
3.3 
2.9 

•2.7 


2.5 

2..". 
2.5 
2.5 


s.a 

1.6 
0.8 
0.4 
0.8 



Vierordt also estimates that, for the entire removal of the carbonic 
acid from the blood, more than three hundred respiratory acts per minute 
would bo required. To some extent the depth of the respiration will 
compensate for want of frecjuency. Thus he shows that in an expiration 
of double tlic usual volume, the quantity of carbonic acid removed is 



imoveu IS 



RATIO OF INSPIBED AND EXPIRED OXYGEN. 

Dearly equal to tlmt wliicU would be exhaled hy respirations of three 
times the normal iVcquency^ and on exauiining a single respiration, he 
demonstrates wliat, however, would obviously be foreseen from a consid- 
eration of the circumstances of the case, that the last portions of the cx- 
]nration arc the ricliest in carbonic acid. Thus the first half of a respi- 
ration contained only 3.72 ]>cr cent, of carbonic acid, the last half 5.44 
per cent. 

AiVith rcs{«ct to tlic ratio between the quantity of oxygen inspired and 
that contained in tlio expired carbonic acid, a variation will p-.i^ofih ' 
be obscrvctl, depending on many conditions, as, for example, fpimi und ex. 
on the nature of the food. Thus, with a carbohydrate, the '"'*'' '**5"S^" 
quantity of oxygen in the carbonic acid will always be less than that in- 
aptred, a portion being employed in tlic destruction of tlic systemic nitro- 
genizcd material which is undergoing decay. This destruction of nitro- 
genizcd material is not sufficient for the support of animal beat, and 
benco cither carbohydrates introduced by the food, or fat already exist- 
ing in the system, must be resorted to for the purpose of making up the 
deficiency. With such variations in the requirements of the system, 
and variations in the nature of the food, the ratio of the oxygen intro- 
duced to that in the carbonic acid removed must also vary. 

For the perfect oxidation of the ditfcrent elements of food, very differ- 
flBt quantities of oxygen arc rciuircd; thus, for the oxidation of 100 
parts of fat, it would require 202. 14 of oxygen ; for that of starch, 1 18. 52; 
for that of muscle, 147.04, 

For reasons to be considered when we treat of the pi-oduction of heat, 
the quantity of carbonic acid disengaged varies with external VariaiionBln 
circumstances. AVhen the weather is cold it is greater than th« niqiired 
when it is warm. Tims at G8° there is twice as nmcb lib- **'' 
erateti aa at 10C°. It increases during exercise and after eating, but 
dimuiishes during sleep. Siorc is set free by men than by women ; it 
Taries witb age, the proportion rising from eight years to thirty, re- 
maining fltationary to forty, and then decbning. It changes with the 
finequency of tlio respirations. The total quantity of carbon daily rc- 
BDOved by respiration may be estimated at eight ounces. 

Besides tiic carbonic acid removed, a large quantity of water is ex- 
cntod by the lungs, for tite expired air may be regarded as WBtrrn-moTed 
saturated, or containing the maximum quantity of water for *" re^i'iration. 
M^. For the vaporization of this water much heat is consumed, as is 
likewise tlie case for t!ic warming of the introduced air, which, no mat- 
ter what tbo cxtcruul temperature may bare been, is brought to that of 
the longs. 

With respect to the absolute amount of air expired, and also the quan- 
tity of water removed by the lungs, some experiments have rcccJitly been 



i 



: 



made by my son» Dr. J. C. Draper ; the principle upon wlucU lUcy vcre 
QiAntitTufair conductcd may be thus brieriy etatcd. Tfa« air from tlie 
M[>irp<rp«'' longSi wliich Irns a ilcw-point of 9-1°, was passed by a wide 
miniiie. ^^^^ tlifOugU & mctuUic coiulcDser kept at '62^, rare being 

taken lo have as little obstruction as possible to its egresa. The weigbt 
of the water collected in the condenser furnished tlic means of calculating^, 
by a simple fonnula, the quantity of air wiiich luul boon expired, for the 
vapor, leaving the respiratory passages at 04^, and that leaving the con- 
dcnsfT at 32°, were at their maximum densities. C-oniputatioos exe- 
cuted upon data obtained on this principle furnish the following, among 
other interesting results: 

1. On making sixteen respirations in the minute, and continmng the 
experiiiicnt for twenty minutes, the average of five difiercnt scries of ex- 
periments gives 622 cubic inches of air expired each minute, 

2. On making »ix respirations in a minute, and continuing the trial 
for twenty minuter, the average of three scries of cxperimcnta gives fill 
cubic inches for the air expired each miimte. 

3. On making thirty-three respirations in a minute, and continning the 
experiment for twenty minutes, tlic average amount of air is 1077 cubic 
incites for the air expired in each minute. 

On comjhiring these throe statements, it appears that, the iirst repnv 
renting normal, the second verj* slow, the third ycry quick respiration, 
tiie absolute amount of air removed from the lungs is directly projMrtion- 
al to the number of respiratory acts iu a giv^i period of time, and this 
notwillistanding such variations in the depth of the inspirations as un- 
der such circumstances are likeJy to occur. 

With respect to the quantity of water removed trom the lungs, he also 
shows, 

QuniKvorwa- ^' '^'"**» ** ^^ atmosplicric tcmpcniturc of 55'^, the 
tcr cjthiiicd [lur polut I)eing49°, the number of expirations sixteen per minute, 
ni nuie. ^j^^ q^j^j^t^y Qf ^vater removed per minute is 4.416 grains. 

5. The other conditions remaining the same, but the respirations re- 
duced to six per minute, the amount of water removed per minute is , 
3.580 grains. ^H 

(5. The other conditions remaining as before, but the number of rei^^ 
piratioua increased to tliirty-threc ijcr minute, the amount of water re- 
moved per minute is 7.500 grains. ^H 

From tlie.sc statements it therefore appears that tlic quantity of wat^^ 
removed from tho blood by respiration increases with the frequency of 
tlto respiratory acts, and this notwithstanding variations which, under 
such circumstances, must take pl-ii-c In their depth. Theoretically, it is 
also ob\Houa that the absolute amount thus expired is dcjjcndent on the 
existing dew-point of the air. Iu the general table, given on page 15» 



dw^^ 




EFFECT OP IlESFIRATIOIT OS TBE BLOOD, 



169 



ftinount of water is calculated from Scguin's cxperiinentd, Lut it ap- 
fipoiu these results^ wiiich aro obtained by a much more accurate 
I that tlio number there piven is undoubtedly too higli. 
The lime of exposure of tlic blood to the air is only a second or two. 
Tlie color cluingcs^ bh lias been dcacribcd before, from blue to crimaon, 
and the temperature rises a decree or two, ats ia shown b)' an examina- 
tion of the left cavities of the heart. The water thus removed is not 
pure, but contains animal matter in a state of decay- 
Though wc have treated of the act of respiration as consisting of two 
Kparate and consecutive stnj^es, inspiration and expiration, Rp!<i<iriitiun » 
in reality it procccthi contumously. At the respiratory sur- I^'j^pJi^^ 
face, which la the wall of the air-cell, the passage of oxygen ing. 
inward, and of carbonic acid and steam outward, takes place in a steady 
I tnd unvaiying manner. The |vriodicity under which it has Ijcen conveii- 
Kient to speak of lliis function concerns only the introduction and removal 
blgjllin from the large air-ways. 

Considering, thexofore, tin' continuous loss of water which the venous 
blood brought by the pulmonary arterial branches undergoes, Eirct of rvfjU 
it must give rise necessarily to a greater density in the blood ^'J,'/! ""/i^ 
' tm the left side as compared with that of tlic rl^ht side of itlowl. 
be heart. The total quantity of blood passing tlirough tlie lungs in one 
atnute is 220 ounces, and the loss of water from this in the same time 
not be more than 7 grains. This, tlierefore, shows that the actual 
^losd of water by the blood during its passage over the air-cclL* is about 
ll^m) part, a quantity which is altogether mapprecialde, so far as its in- 
floence on the spccitic gravity is concerned, and showing ns that the ob- 
Kirations which some experimenters have made on this point, with a 
riew of demonstrating an increased spissitudo, density, or cohesiveness 
Lof the blood on the left side of the he4irt, from the giving up of its water 
'ta it passed through tlic rcsjiirator}' oi^an, aro either exaggerated or af- 
fected by some deceptive cause. 

The introduction of an irrcspirable gas into the lungs, or the prevention 
of the access of the atmosphere, brings the circulation of the Kirdiuftiicin- 
blood to * stop; for tliat movement dciHjnds, as I have shown, i,7plpTrftU« 
on tiie aeration taking place in the pulmonary capillaries. In kuw. 
■ncii CMBta there will be an engorgement of the right heart and vessels 
ariflti^ therefrom, but, if the sto])page has nol lasted too long, ttic current 
I may be re-established by re-establishing the respiration. Death com- 
monly ensues on an exclusion of the air for five minutes, and, in cases 
Lof drowning, it is nirc for restoration to be effected if the immersion has 
more tlian fuur. 
In the respiration of protoxide of nitrogen, a gas which is an energetic 
fnpporter of combustion^ and acting more powerfully on the animal sys- 



170 



EXPESIUEKTS OF JIEGKAULT AXD &£I8£T. 



_ of roi **^"* when rcspiretl than even oxjgen itself, on account of its 
»xlJ« of mm*- ready condensibility by prcsBure, or by mt^mbnines. and sol* 
*"*• nbility in water, tlie circulation is greatly qnickcncd at first, 

and a state of exhilaration cnsnes ; bat tbis is soon followed by a 
dition of depression, or even of coma, for the quantity of cnrlxinic 
produced in tlie syfiteni is now bo groat that the lungs ore wholly iiUKk- 
qualo 1o otTect its removal, and all the fymptoma of poisoning by car- 
bohic acid come on. 

Zimmerman found that a rabbit exhaled 12^ grains of carbonic aciil 
per hovtr wlicn brcatliing atmosphe-ric air, but that tlic quantity rose at 
onee to 20 grains j)cr hour wlicn it was caused to breathe protoxide of 
nitrogen. But by far the most complete and important sencs of expcn- 
Summflrvnf mcnts yct madc in regard to tlic relations of the aerial mo- 
itoinxiuitBind dium and the respiring animal is that of MM. liegnault and 
im«ni»'oq*m^ Kcisct, pubHshcd in the Annales de Chtmio, Juillet. 1849, of 
pintion. wJiich, sincc it may be taken as a model of physiological in- 

vestigation, a brief abstract is here given. 
rtn. Rl. 



L^ 




The apparatus thcv 
employed is represented 
in J'^ff. 81. It posaesset 
the great advantage orer 
all exjXMimental ortv^ 
mcnts heretofore employ- 
ed in permitting an ani- 
mal to l>e kept cx'ea for 
many days in a limited 
volume of air, hut under 
such eircfumst.'incca that 
tj|wiiiii«iiu vo rvapinLoD. that uiT wos coiistantU* 

kept at its normal compr>8ition by the automntic motions of the instru- 
ment itself: oxygen being thus furnished as it was required, and car- 
bonic acid removed. 

Tlie arrangement consists of three parts : 1st, a cliambcr or bell, /, for 
inclosing the animid, surrounded by a jar tilled with water, the tempera- 
ture of which could be ascertained by a thermometer, i'. In the interior 
of the bell was a ptatfonn i>crforated ivith holes, hy the aid of which the 
excretions could bo collected. On one side, at/», was a pirssure gauge, 
connected with the Iwll by a tube, and shomng the condition of conden- 
sation or rarefaction of the included atmosphere. 2d. At the same side, 
the hell communicated, by means of India-rubber tubes, jn, n, with two 
cylindric vessels, y, r, filled with a solution of caustic potassa, and whicli 
were driven by the aid of ])Owcrt\d clock-work in aneh a way tliat the 
one alternately rose and the other descended, the flexible tube s pcnnit* 



SXP£SIME>TS OF BEOKAIXT ASTD REXSCT. 

tinp thU motion. The result of tiiis was liiat a portiou of the air of llic 
bell waa alternately drawn iiito cucli of the cylmdric vessels, its carhon- 
ic nci<l removed by the potasht and then it waa returned ; so, as fast as 
tlio animal produced tlwt gas by breathing, the potash removed it, giving 
rise, tberci'orc, to & tcndeney to a certain amount of rarefaction in the air 
of the bcli ; bat, 3d, on the opposite side of the bell wcro placed three 
Ttcqytocles, tf, e\ f\ filled witli pure oxygen gas, wliich flowed into tl:c 
bell through the tul)es /"/'./^/'.y*'/', to compensate for that rarefaction, 
coming in by a bubble at a tiino tlirough the littlo potash Husk i, liic 
oxygen being pressed out of tlie rcser\'oir8 by a solution of chloride of 
calcium dc.!icendiiig through a stop-cock, c, from a reservoir, b 0\ kept at 
a vonstaul level in tiie usual manner by the flasks a, a\ e^'. As fast as 
one receptacle was exhausted, the pressure tube was successively con- 
nected with the others, and so the supply kept up. Attaclicd to the 
atand supporting tlic animal was a eudiometer, i?, which enabled a small 
quantity of air to be witlidrawn from the bell at any moment for the 
pur[wsc of auEilyticai examination. For other details of this apparatus, 
and the jiarliculars of its method of use, reference may be made to the 
original memoir itself. It is suiBcicnt for the pre-sent purpose to under- 
stand tlmt an animal could Ijo kej>t in the interior of this bell for sevenil 
days witliout showing any signs of discomfort, pure oxygen being sufw 
(died to it. and the carbonic acid produced by breathing removed tiy the 
play of the machine its<-lf. 

The following is an abstract of the results obtained: 

1st. iIot-bK>oded animals, maniinaha and birds, under their ordinary 
diet, always disengage a little, nitrogen by respiration, tlic m-. m^^ j 
amount varying from less tlian yj^ to -^ of the weight of anima]. on an 
tbe oxygco they consume. onUnary din. 

2d. M'hen these animals are fasting, they often absorb nitrogen in pro- 
portions similar to the preceding. In like manner, an absorp- Theiamo 
tiori of nitrogen was obser^-ed after starving tiie animal, and then *«»ii"e- 
submitting him to a diet very ditfcrent from his ordinary one, and also 
during sickness. 

3d, The ratio between the quantity of oxygen contained in the car- 
bonic acid and the quantity consimied depends more on the i„gyj,j(, ^ 
ztatnre of the food than on t}io class to which tho animal be- ru<Ki aud iiuc- 
loBgs, being, when the animals arc starring, the same as it is ^^' 
uriktti they are fed upon meat, or perhaps a trifle less. Irom tliis the 
intrrrating conclusion may be drawn that a stnn-ing animal furnishes to 
the air of respiration his own substance, which is of course of the same 
nature as the tlesb ho eats when dieted on mcaL All hot-blooded ani- 
mals present, when tliey are starring, the respiration of carnivora. The 
ratio for the same auimal varies from 0.62 to LO-l, according to the na- 
ture of the diet. 



172 EXrEUlUEVrS of REOXAtXT AND HEISET. 

4th. In fowls, Rubmitted to thHr nsnal diet of grain, there U oAen 
Rr«T>inilqu niOFc oxA'gcm in the carbonic acid diri^cngaged ttian was fami&hed 
uf binu. i„ tbg j,iy by respiration. The sur|}tua of course coined from 
the food. 

6t]L, The; qimntit? of oxrgen consumed in a given time varies nilk 
I fl of ^^^ Bttlc of digestion, motion, and other circnmstances. C«n- 
motion, »gf, pared tnjrether, the consumption is greater among the young 
''" ' ■ th:m among adults, greater among those tliat are Jena but in 

good health than among those that arc fat. 

titJi. If wc take an cijual weight of the aiiimnla under examination. lh< 
imluenwof quantity of oxygen variea much with their absohite «i2ej 
iiie lixQ of uii- thus it is ten times greater among little birds, such as 9pa> 
'" rows and green-finchcH, than among common fowls. This 

is owing to the fact that^ since tiicnc diflcnmt species have tiic same iQHh 
j>emtuTc, and the little ones present relatively » grcotcr surfiKO to th» 
amhicnt air, they must consume relatively more oxygon to keep up their 
heat to the standard degree. 

7th. Hiboruating animals, such as marmots, when perfectly awake, cx- 
Ucs ' I'o f ^'''^'^ ■"* ]>ecnliarity, Imt when fast asleep often absorb nilto- 
hibcmming gen. The ratio of the oxvgen contained in the carbonic aod 
ui tu . j^ ji^^ inspired is very low, scarcely amounting to 0.4, tliA 

missing oxygen escaping in the compounds of the urinary sccrctioilS 
but since tliis removal takes place only periodically, the sleeping marmot 
exhibits the remarkable i»henomenon of increasing in weight by rc^piw* 
tion alone. 

Sill. Tlie consumption of oxygen by sleeping marmots is very small, 
scarcely ^^ of what they rcc]uin; when awake. At the moment thqr 
awaken from their Ictlinrgj', their respiration becomes extremely nctive^ 
and during the period of their awakening they consume much more oxy- 
gen than when tliey are completely awake. Their teni[)eraturo rises wp- 
idly, and their members gradually lose their stiffened state. While tor- 
pid they can remain witliout difticulty in an atmosphere which would 
I suAbcatc them in a few moments if awake. 

^^P 9th. Cold-blooded animals, for an eipial weight, consume much less 

^^^ Iio«niration of o^yg^° *han hot-bloodcd. Frogs wiili their lungs cut out 
ft e«irt-i.!owied continue to breathe witli nearly the same activity as before, 

r " 
I ' 

L 



aniD««. often living for several days, the proportions of the 
ab8orbe<l and disengaged diflering little from what is obsen'ed in the 
ease of uninjured frogs, This shows that their respiration can bo con- 
dHctc<l by the skin. The respiration of earthworms is the same u that 
of frogs, as regar<l3 the quantity of oxygen consumed, when they are com* 
pared under an equal weight. 

10th. The respiration of insects, such as May-bugs and silk-wonns, 




KERTES OP nESPIRATrON, 



173 



» 



I 



is mucli more actire tlmn tlmt of reptiles. Under on equal iteiipinuian of 
«'eight they consume nearly as much oxA'gcn us mammalia: *'"«*■■»»■ 
the comparative lowncss of their temperature is due to tlie relatively 
great aartacc and moist exterior they present to the air. It is to be re- 
marked that we are here comparing the respiration of insects with that 
of inaniniulla whoso weights may lo from 2000 to 10,000 times as 

11th. The respiration of uulmals of oiflercnt classes, in an air con- 
taining two or three times as much oxygen as the atmos- Kiifeoi <>f iii- 
}»herc, does not differ from existing respiration ; indeed, tlic ][m**H?af'* 
animals do not ap[)car to pcreoivc that they are in a medium ygcn. 
difi'eront from the ordinary atmospltorc. 

12th. The respiration of animals in a medium in whicli, for the most 
part, hydn»gen replaws the nitrogen of our atmosphere, scarcely ditfera 
(rora existing re.sj>iration ; only there is remarked a greater consumption 
of oxygen, due perhaps to tlic necessity of compensating for llie increased 
cooling arising from the contact of hydrogen gas. 

TIio introduction of air into the system is, to a certain extent, auto- 
matic and, to a certain extent, dependent on the will. In tranquil res- 
piration wc are wholly unconscious of the motion; the ex- j;,^^^ j„, 
citing impression is made on the pneumogaslric nerves, and, voivwi la n% 
being conveyed to the respirator}' ganglion, tiie racdulk ob- i'*"*"'"'* 
looyfa, is there so reflected that through the agency of the phrenic nerve 
motion takes place in the diaphragm. Tlic automatic, and therefore un- 
couaciouA movement, to a certain extent, occurs in that way. Hat there 
is no doubt tlmt the brain also participates in tlie function. No other 
evidence of lliis is required than tiiat wc can *'hold the breath,'* and the 
ndativc share that the voluntary and automatic mechanisms take is iUus- 
ttaled by the circumstance that this holding of the breath can only be 
penisted in for a certain time, w*Iicn the necessity for re?piring bocoracs 
tltogetber QneonlroUable. 

It is not, however, to be 8upj>osed that so important a condilion as 
iKot <»f the intitxluction of the air is oidy slenderly provided for. JIauy 
other nerves, besides tliosu mentioned, tuke p;irt in it directly or indi- 
rectly ; the fifth pair, the ner\-es of tlie general surface, and also the great 
Bvmpathetic, the intercostals, the Bpiiiid iiccc-ssory, which probably gives 
its motor property to liie pncumogastric, Ojiinion has differed res|icct- 
ing the cause which produces the nucessarj- impression on the receiving 
iier^'CB, some referring it to the presence of venous blootl in the capilla- 
ries of the lungs, and some to the carbonic acid in the ccUs. i^loreovcr, 
there is reason to believe that the presence of an abnormal amount of 
venous blood in the respiratory ganglions will of itsi^lf give rise to res- 
piratory movements through tlie proper centrifugal nerves. 



RESULTS OP RESPUUTIOX. 

TUo control possessed by tlic will over the introduction of air stands 
ftftpinitum in a close relation to the production of articulate or otW 
u" «Bd put- sounds, and therefore to intercommunication between indi- 
te aiKAButlc viduals hy speech. This involves not merely a general con- 
trol alone, hut also a particular onc^ which is reached hy regulating the 
movements of the glottis by the agency of the superior and inferior laryih 
geal nerves, But tiiough the will for these ijiiporlant purposes c.xcrciaes 
80 marked a power of regulation, it is to be looked upon as superadded 
or incidental, and during el<x\\ coma, and tliat larger portion of life whtc& 
is spent in total inattention to the carrting on of tliis function, it is dis- 
cliarged in a purely automatic way. 

The mechanism %vhich accomplishes the surprising results of rcsptrt* 
Rosuiti of TVS- tion may therefore well challenge our admiration. Asa 
piratmn. self-acting or automatic contrivance, over which we liavc not 

a necet^sary control, it originates in a single year nearly nine millions of 
separate motions of breatliing. It never fatigues us; indeed, wc an 
never conscious of its action. In the same lime, a hundred tJiousand 
cubic feet of air have been mtroduccd and expelletl, and more than thir- 
ty-five hundred tons of blood have ^)een aerated. In a future i>age we 
shall have to present the wonderful mechanism by which ar rial eurrcnta, 
as they pass in and out of the respiratory apparatus^ are incidentally em- 
ployed as a means of producing nmsjcal notes or articulate sounds, and 
of thuJi establishing a relation and communication between different i&- 
dividuals. By these the feelings and thoughts are diffused, and in a 
mechanical origin commence those bonds which hold society together. 



ANIMAL HEAT. 



175 



CHAPTli:R X. 



^ 



k 



OF AXIMAL HEAT. 

PartidpativR t^f Ortpmc Form* in frtervat Variafhnu of Trmprrafvrt. — ifttAanitm/or cowihr- 
halanfimy Ikeu VttndilioHs. — Devttopment of Urat in I*lanla at (Sfrmitiation and InffortMotrf. 
— /(« Ctmtg M Oritioliim. — Cwiatrfion of Rtsjriration atul Hrat. — Tftfrfuraiure of Afan.-^JJU 
I ^mrtr «^ Hmgtamce. — 'J7te tlivrnai I 'ai-iatiout vf Utat. — CcimtctioH of thea6 VaritUiuaM teitk 
mT/ame JWodtaUim.—Ai>itwl Vtmations of Htnt. — Contrt^over them ty Food, L'iotking, and 
SMbrr, — Soirre of Auiimd IJent. — Kffivi of Varuitiimz in iht Food and in the respired Afo- 
dmm^lotAiurtspeetM Ha Xatun atul HurrJactioH. — Jlifl/ema/ion. — Slorvatitm. — Artificial JiO' 
dKfiM qf Temperalwrt fry Hhod-kitiny. — Prindfdts of Jirdmctitm ^ Temperahm. — Jladiiu- 
U m, Omtart. — iA'tiffOrution. — Their iSttUna; tfilh the Ucaiing J'roeena. — Loaal VariOf 
lim» tiiantuaed fcy c^«: VirrulatiaH. — Coatroi by (he Nervou* Sjfsleta. — Itt pfijffieai Nahm, — 
AOotrofnan of Orytnic Uodtt*. 

Owing to tlie earth's diurnal rutatlon on its axis, and its annual move- 
it of transUtion round the sun in nn orbit inclined to the ^ . .. . 

Vanaiions of 

ilor» variations of temperature arise, tJie vicissitudes of cMcm«ito»- 
Mimmcr and winter, day and night. i-tratur*. 

In these variations all objects upon the surface of the planet partici- 
pate; organic forms are no exception. As the heat of the medium in 
which they live ascends or descends, the'u-s follows it at a rale depend- 
ent on tiicir conductibility. 

lake mineral substances, the more lowly forms of life submit to these 
changes. They have no provision for check or comj)cnsation. Org^nk- forms 
in summer, the temperature of the stem of a tree rises with- fhc^'^vnri^"* 
out any restraint; in winter it declines; and, sliould the ^^m. 
point be reached at whicli thoee nutritive changes that give motion to the 
sap cease, nothing is done to arrest the descent, and the whole organism 
puses into a state of torpor, hybernation, or tcmporan.' deutlj. 

Now, since this tbllowing of atmospheric temperatures must take place 
in ei'cry organism as well as in every mineral body, the con- Conipfouatitif* 
Btmction of one having a uniform mode of existence in all "7t!lfhk;™e" 
climates and nil seasons implies a resort to sonie subsidiary tribes. 
mechanism, which, though it may not check, may yet com)jcnsale for 
tliese vicissitudes. Accordingly, so nearly is this equalization accom- 
plislied in tlie highly-developed tribes, and a standard tcmpcrntnrc so 
nearly attained for tliejn, that many physiologists, misled by imperfect 
obaer^'ations, have concluded that such living beings are emancipated by 
nature from the operation of physical laws : an erroneous conclusion, for 
in thcra that action is only concealed. 




176 THE B£AT OF PLANTS. 

In diffeTcnt races, the mcdumism hy wliicU these variations of atmoa- 
plieric tcui|>crature are balanced nets with different degrees of }>crfeclioi>. 
On this a subdivision has been foundctl, and animals claMt- 
LlomivO Bill- ficd as the cold and hot blooded. We arc not, however, to 
"* ■ nttocli much ini(Kjrtance to such an arrangement: it is ratiia 

itnagiuar^' than founded on any real distinction. In man, the tcmpetn* 
lure is near 100=" ; in fishes, it is about tlmt of the water in which ihcy 
live. Insects, iii their lar>'a and jiu^ia condition, arc cold-blooi^; in 
tlicir perfect condition, hot, 

AVe li.ive now to explain wliat physical principles arc resorted to in 
solving the problem of maintaining an organic form At a constant tem- 
perature in a medium the heat of which is variable ; and as we maj 
reasonably anticipate that these principles are the same in every tribe of 
life, it will facilitate our investigations to commcucc with the simplest 
cases first. 

There are two periods in the life of a plant during whicli it simulates 
Tw«(>eriinNc^ the fuuctions of an animal in maintaining a temjjcratarc 
liem in jilant*. bighcr than that of the surrounding air. These periods are, 
1st, at the germination of the seed ; 2d, during tlic functional activity of 
the ilowcr. 

If a mass of seeds be laid together, as in the making of malt, the op- 
Heat afgcnn. cration being conducted ut a gentle tciuponilui*c, and with th« 
iiiatioii. access of atmospheric air, oxygen disappears, carbonic acid is 

set free, and the tcm|xiraturc rises forty or fifty dcgreea. A process of 
oxidation must therefore have been carried into etfcct, and to it we trace 
the heat disengaged, for carbon can not produce carbonic acid without a 
rise of temperature ensuing. The loss of weight which a seed exhibits 
is therefore dnc to its loss of carlwn, nnd the whole effect is ex{ilaincd in 
llic statement that atmospheric oxygen has united with a i)ortion of car^ 
boti eontaitied in the seed, producing carbonic acid gas and an evolution 
of heat. 

Again, during flowering, the same action is repeated. The flower re- 
lifiitofin(li>. moves from the surrounding air a portion of llic oxygen it 
r-acMice. contains, and replaces it with carbonic acid, the toni)>enituit 
rising, as accurate exixjriments have proved, in absolute corre8|»ondence 
with llic rjuuritity of oxygen c<:insumcd. Nor is tliis elevation insignifi- 
cant. A mass of fiowers has been obsen'ed to raise the themiomcter from 
«6<> to V2l=>. 

l£ thus the disengagement of warmtli is the result of oxidation, it nmst 
OxMaiiofi ih« dependontlieprescneeofair, and be regulated by the rapidity 
•TeMiilwor ^*''^ which oxygen can bo supplied. As we pass from the 
ietnp«niture. ccmsidemtion of plants to that of animals, we discover tlint the 
production of heat must le connected with the power and precision with 



COXXECTTOX OF BE^PIRATIOX ASD IlEAT. 



177 



rlucli the respiiratory a])parfthis works, for it is throngh its agcncjr that air 
I inirodaccd. Extensive obscn-ation accordingly establishes a close cor- 
Duik^nce in eacli animal tribe between the quantity of heat produced and 
be cajKibility of respiratory apparatus. The lower tribes breathe slow- 
■ ajid arc cold. Kaithworins are only a degree or two warmer than the 
ad ; and even among vertebrates, fishes are only two or three degrees 
rarmer than the water, a lowiicss of temperature in a great nicasuro de- 
ling on the high cooling agencies which that liquid ex- „^ . ^ 
, its sjweiKc heat, and tiie f;icility with which currents are n-rtiiirmionMnil 
Btablishcd in it. However, «sven in these cases the produc- "^ 
tiou of heat depends on the [jowe-r of the respiratory engine. The bonito 
can kcpp its heat 20^ above that of tiie sea, and the nam'hal maintains 
s steady tempcmtarc at 96*^. 
K The organic operations involved in nutrition, and also the retrograde 
^Uianges of decay, can only go on at their accustomed rates so jnTarifti.iUiy 
■DOg ftS standard limits of temperature arc observed. The ofor^auicic- 
"proper progress of the actions of life implies a corresponding deflnit«'icBi. 
ftdjustmcut of heat, and this irrespective of tlie mere size of i'""*""- 
the animal. Even those that arc microscopic must come under this mlc. 
jVlicn the tcmj^raturc of a liquid containing infusorials is caused to de- 
ad to the freezing point gradually, the last portions which solidify arc 
t which sun-ound each of these little forms ; a drop is kept liquid by 
be heat they disengage. In the same individual, the absolute tcmpcra- 
Lii« will depend on its respiratory condition ; thus insects, in passing 
ttirotigh each of Iheir stages of metamorphosis, present a definite condi- 
on as to their heat : the larva of the bee may bo only two dcgiccs above 
air, while the ],»erfect insect is 10"^. Whatever aceelcralcs the in- 
iuctiou and expulsion of the air, increases the warmth ; Varkiion* of 
■o A beo shaken in a bottle, and kept in a state of constant it^nrifU'dii 
muscular exertion, will raise the temperature contained there- tJon- 
at £ur higher than if he remains inactive. Among insects, those having 
ibe largest organs of respiration have always the highest tcm{}erature; 
and, aince muscular motion implies destruction of muscular tissue by ox- 
idation, and thcrctbre devehqinnnt of heat, we should expect to fmd, as 
ia actually the case, that animals possessing the highest powers of loco- 
Kmotion w ill possess also the higlicst temperature. Of all, therefore, birds, 
Vthc endurance and energy of whose powers of flight result from llic per- 
fection of their rcspiratoiy mechanism, have the highest temperature. It 
ia ftboat 110"^. Yet even here there ore diiferencea: tlic sluggish ham- 
L door fowl has not the heat of the energetic swallow. 
■ The standard temperature of man is nsually stated to be 9S°, hut from 
"this mean it ranges within certnin limits upward and down. Tanpmtura 

IUach dep-cnds on the state of the he^dth; of course, eveiy thing *'^"'»»- 
: 



178 



DU-RNAL VARIATIONS OF HEAT. 



on tbie respiration. Li fevers it will rise to 105°; in tetanus it may leicb 
110°; the contrary in astlima, when it may sink to 82*^, owing to impo- 
feet access of air ; in cyanosis to 77°, owing to imperfect aeration of the 
blood ; in Asiatic cholera to 75^, owing to the non-reception of oxygen by 
the cells in their diseased state. It ulso varies with the period of lilc: 
in the new-bom infant it is 100°; it presently sinks to 99^« and rises 
dnring childhood to 102°. Ifcntal exercise in tho adnlt increases it, 
bodily exertion still more. The sj)ccial degree varies with the point f» 
which the observation is mode : the limbs arc colder than the trunk, SDil 
lliis i.s the more marked as the point is more remote. On the leg the 
tcmpcfatniQ may be 93^ ; on the solo of the foot, DC ; while that of tho 
viscera is 101°, 

In his residence in diflbrent climates, man is exposed to variations of 
RHlxunrrof temperature which extend over a scale of 200^. Toward 
tiM human ..r- ^jj^ p^^i^g (!,(. ^old of wintot 13 ol^cn —60^; in the tropics 
pmlsni to ex- * -11- t 

tniiniia ur tcio- the heat of summer + 1 30^^. r or a short period bis power of 

twntutv. resialanco is greatly beyond what these nnmbera would io- 

dicate; he can enter with impunity an oven heated to 000°, provided the 
air is dry. In tUeso eoAes, thougli excessive evaporation from the akin 
moderates the effect and keeps it within bounds, there is always a mark- 
od rise of tcmperatiiro of tfio whole bodv. In a corresponding manneZi 
exposure to cold produces depression, us shown in Dr. Davy's obsem- 
tions. At 92^ of tho air, a tliermomctcr under the tongue stood at 100|°; 
at 73° it stood at 09^ ; at (JO^ it stood at 97 i^. 

Among these variations there is one eUtsa which calls for critical at- 
DinrniU raria- t*^"^'*^"' '' *3 tlic tliurmd Variation ; less marked in roan, 
Uoninilicti>;at who iustiiictively makes jjrovision against it, but well shown 
in tho case of fasting animals. This illustrateSi in an inter* 
esttng manner, the controlling inHucnce of external conditions; for if ex- 
posure to a high temperature, as that of an oven, compels a rise of the 
heat of the whole body, in spite of tho conservative arrangements, and 
exposure to extreme cold compels a descent, we onght to expect that €ix- 
poaure to more moderate degrees would, in like manner, produce an im- 
pression. 

Tiic old astrologers were therefore not altogether wrong when they af- 
firmed tlie doctrine of planetary influences. The diurnal temperatures 
of a locality^ as dependent on the position of the sun, are expn*ssed in 
the system of man. The mininmm of heat for tho night, and tlic max- 
inmiii for the day, find a correspondence in tho decline of animal temper- 
ature at the former, and its rise at the latter period. The experiments 
of M. Chossat on birds submitted to absolute star\*ation showed that, 
though in their normal state, at the commencement, the variation between 
midnight and noon was only 1^°^ it gradually increased to 6°, until at 



d 



CALORinC INFLUENCE OF FOOD. 



in 



ist, the generation of lieat wholly ceasing, the temperature gnvo way 
jrapidly just previous to death. 

If, therefore, it was po3siI>le for life to continue without the evolution 
lof animal heat, it would be with the body as it is with the steni of a tree. 
lit wodIiI follow the ihermometric variations in the air, the maxima of 
Lbcat and cold hcing Komcwimt later than the aerial ones, and within nar- 
[rowcr limits, by reason of the low conducting power. The nearest a|>- 
Iproach to this is in cases of absolute starvation, and though in niun tlie 
[cfiect is masked by the due taking of food, it none the less exists. In 
I human communities there is some reason beyond mere cus- influence of 
torn which has led to the mode of distributing the daily f^ii^jj^jj^ 
meals, A savage may dispatch his gluttonous repast, and «iure. 
I iben starve for want of food ; but the more delicate constitution of tho 
oriUjEcd man demands a perfect adjustment of tho supply to tlio wants 
kof tho system, and that not only as respects the kind, but alsotbe time. 
lit eeeina to be against our instinct to commence the morning with a 
[heavy meal. AVc break fast, as it is significantly termed, but we do 
RO more, postponing the taking of the chief supply until dinner, at tho 
I middle or after part of the day. If men were only guided by views of 
leconomy of time saved for the pursuits of business, or if, on this occasion, 
jthey put in practice the nde they observe on so many otliers, of never 
Ipostponing the gratification of their desires, tho first affair of the morn- 
ing would have been an abundant repast. But against this something 
villiin us revolts, and that in all classes, the laboring, the intellectual, 
llie idle I think tlicrc are many reasons for supposing, when wc recall 
the time which must elapse between the taking of food and the comple- 
tion c^ respiratory digestion, that this distribution of meals is not so 
nnsch a matter of custom as an instinctive preparation for the systemic 
riic and fall of temperature attending on the maxima and minima of daily 
heat- The light breakfast has a prejwiratory reference to noonday, the 

tcoKd dinner to midnight. 
Once more I would remark, that wc must not be deceived by the 
masked aspect which the system in this matter presents. c«mncrtion of 
Tla dtnmnl variations are concealed by acencics broucht v«naiion«of 
specially mto operation for that purpose, but they exist in f^„ic pcnodt- 
tbc physical ncccsRitics of the case; and herein, I believe, ^^^'^ 
m have a first glimpse of ttic canso of those periodicities, which physi- 
cians from the earliest times have remarked; for, though the ncn-ous 
lystera. both in a state of health and disease, may seem to be their ori- 

Ipn, it ia not impossible that its cliangea are connected with variations 
thus taking place in the external world. 
Wc have next to consider tho effect of the annual varia- Annual v«ri». 
tions of temperature, which reach their maximum soon after tlMMofiwtt 



L 



180 



EFFECT OP AKSUAL YARUTIOXS OF HEAT. 



raitUsnmmcr anJ their iiiinimum soon after mid-winter, the manner in 
which the system coniiwrta itself under them, and the means whicli in- 
stinct and experience teach us to employ in pronding against thcnu 

The tallica of niortaLity show that tliere is a loss of life at the anmi&l 
Effi'ctof n- '"^'^'''^""1 *"J minimum ut' Icmpemturc which greatly m- 
at rarUtiuiis cccJs the average of any other j>eriod. In England and Bd- 
va mta. glum, where tlic mean tem|K'raturc of the summer months is 

moderate, this ia not so strikingly mai'ked for those months, and the chief 
loss falls upon the winter ; but in New York, which has a summer cor* 
responding to tluit of the south of Ku rope and a winter like that of the 
north, tlic etlcct of these extremes becomes so obvious as ei'en to be 
popularly connected with the [xisition of the thermometer above or bebw 
65°. Among infants and the aged, whose controlling powers over tem- 
perature are imperfect, tliese effects ore most distinctly ivitncsscd ; bol 
among healthy adults, and even in Europe, wo can detect them on crit- 
ical examination. Thus, in Brussels, the monthly mortaUty for Jamua7 
being taken as lOfj, that for July is 91, for August 9G, and for Octohw 
93 ; and it is to be rc^Uccted that these arc the residual traces of the 
operation of cold and heat after all the precautions Iiavc been used to 
ward them otf. I might make here the same remark that was ina^ 
when considering diurnal variations, that the true effect is so masked and 
concealed that we arc liable fo undervalue it, and do not properly appre- 
ciate this tax ]mt upon the system, 

Tiicso annual variations of exteniul temjKraturc arc cliiefly combsted 
Control oTrr ^X food, clothing, and sheltcj-. The dietetic changes we. make 

aanujUvam- between winter and aumnicr are founded uiwn the principle 
ijotu iiv rowi, ^ . 1 -1 1 ,■ 1 • 1 *- .1 

doUiiDj;. »bcl- 01 usmg more combustible looa lor the fumicr, and lc5S com- 

'*'* bustiblo for the hitler season ; and, since tho caloriHc ef- 

fect of an article of foo<l greatly depends on the quantity of oxidixable 
bytlrogcii it contains, the winter diet haa moro of that clement than the 
summer. Partly ihns by varying the nature, and partly by rart-ing llw 
quantity of the food, we can effect a compensation to a certain extent. 

Of the manner in which the dict-compcnsation is aided by variations 
in clothing little needs to be said. The experiments of Count Rumfozd 
established the fact that the conductibilJty of summer clotliing is greater 
than tliut of winter, and tiicrcforc its resistance to the escape of heat is 
less. It is snflicicnt mci'cly to allude to tho control which is gained by 
diftcrenec of thickness in the garments, and by their amount or qtmn- 
tity. Wc instinctively make tliese adjustincntH to meet the existing ex- 
igencies, and, as for as may be, in this manner aim at a medium effect. 

The cheek ujioii exteninl temperature by the use of clothing was doubt- 
less one of tht: first contrivances of the human race. Even of savage life 
it is a cardinal feature. The check by adjustment of diet belongs to a 



4 



DIPERPECTIOSB OP SHELTER 

cirilizptl sfate, since it implies a certain control over the Qiiimal appetite 
I and peisonal self-denial. Though great iniprovcnients in both oftlicse 
1 will doubtless lierearier be made, when the principles of their operation 
ire more generally and better understood, they must, even in their pres- 
I ent condition, be regarded as having reached a higher perfection than the 
check by resorting to sliclter. The art of constructing dwelling-houses 
may bo said to be yet in its infancy in all parts of tlie world, „ . ^ 
ancl yet in po jtarlicular is the physical condition of females ptrfoctiom «f 
and children, and especially of the sick, more nearly fouclicd. **'"'**'* 
Is is oidy within our own times that attention has been drawn to the 
' proper methods for the admission of warmth, and air, and light ; the hy- 
gienic iufluences of furniture and decoration arc unknown, beyond, per- 
haps, a popular impression tliat it is unhealthy to he. in a recently-paint- 
ed apartment, incxjicdrent to sleep in a rhainbcr where there are flowers, 
and uiiplcas&ut in summer to have a carpet on the floor, because it looks 
Trarm, ond is thought to generate dust. The owner of a palace, on which 
wealth has been fruitlessly lavished, finds, on a cold day, that he can 
not obtain from his parlor tiro tlic necessary warmth unless by alternate- 
ly taming round and round. The testy valetudinarian sits In his eiisy- 
rhxir, tonncntcd by drafts coming in from ever)* quarter. Tn his vain 
attempts to stop the otfcnding crevices, it never occurs to him that his 
dunmey is a great exhausting machine, which is drawing the air out of 
ani, and tliat hl.^ means of warming and ventilation are the most 
hlo that could be resorted to, since radiation can warm only one 
aide of a thing at a time, and frcsh sir under those conditions can only 
be introduced by drafts. 

To warm rooms by contrivances such as the open fire-place or stove 
is obviously unphilosophical, since the efiect of these is to ex- ofnntficUl 
hanst tliC air of the apartment. The modem method of warm- **™"h. 
lag by furnaces, which act by throwing air duly moistened and of the 
right tem}ieraturc into the rooms, and therefore by condensation, is clears 
ly a better system, since it not only puts an end to all drafts, the 
tendency being to force air out through every crevice instead of drawing 
il in, but it possesses the inappreciable advantagc-s of giving uniibnnity 
of warmth, a perfect control over the degree of heat, and likewise over the 
ftstorc of the air. which need not bo drawn from the cellar, or the con- 
taminated impurity of the street, but by suitable flues from the free and 
clear sir abovc^ Ventilating contrivances which can cheaply and effectu- 
ally force a supply of artificially cooled air in the summer, and warm air 
ia the winter, into dwelling-houses, are still a great desideratum. 

By the aid of diet, clothing, and shelter, wc are able to effect an almost 
ooniplete compensation for the changes of ditumal and annual tcmper- 
, mod even to occupy any climalo of the globe. It is the manage- 



182 



EFFECT OP C03Uil'STIBLE AUMEXT. 



meat of caloric which makes man vrhat he is, and constitatcs his special 
prerogative ; his degree ofskill therein is the measure of his drilization. 
The distribution of plants and aniniold, or, rather, their limitation vitliin 
fixed boundaries, depends on the distribution of heal, but from these te- 
straints man h free, l)ecAUse he can control tcmpcmturea. 

From these considerations of the effect of external heat on the Imnan 
mechanism, vo return to a more critical examination of the modes by 
which heat is gcneratwl, and its degree nrgiilatcd in the body. 

In every instance vcc assert tliat the production of animal heat i» due 
SotuwofanE- to oxidiitiun taking ]>lacc in the economy, and g:iving risett* 
aiAi hML carbonic acid, water, and other ooUatcnd products. It is not 
necrasory to attach any weight to the cxiicriments of Dulong, which seem- 
ed to indicate that not more than four iiftha of the heat actually pro- 
duced could he owing to the oxidation of carbon, nor to those of a like 
kind of Dcsprctz. The method they resorted to for the measurement ot 
the disengaged heat was open to error ; the nmubcrs they employed u 
representing the combustion heats were imrorrect ; nor did they make anr 
Allowaneo for other substances, such as sulphur and pboBphorus, whidi 
are simultanoonsly oxidizing, and the products of their combustion escap- 
ing by the kidneys. 

Keducod to its ultimate conditions, the evolution of animal heat de- 
E(r«ct of mora pends on the reaction taking place between the air intnv- 
iiim««L '••"oi- ^""^^ ^y respiration and the food, and as either one or other 
cohol. of these is touched, the result may Iw predicted. If, for es> 

ample, into the digestive canal alcoholic preparations bo introduced, the; 
are absorbed, by reason of their liquid condition and ditiusibility, wilk 
readiness. The combustibility of alcohol, and the amount of beat it 
yicldi!, are so grent, that the priman' ctfcct of the oxidation which ensues 
is a warmth or feverish sensation. By reason of the changes wliich arc 
now taking place so actively in it, the blood circulates with unwonted 
rapidity, and the supply to the brain incrcn.'^ing, that organ exhibits as 
unusual functional activit}-. But this display of intellection is oidy tem- 
porary, and an opposite condition soon comes on, for, more carbonic add 
accumulating in the blood than the lungs can get rid of, the depressing 
effects of tliat body commence, and eventually the symptoms of poison- 
ing by it ensue. 

Not unlike tiiis is the train of effects which arise when, instead of va- 
Effeciof.more ryiug thc nature of the article ingested, we vary that of the 
tarur'of relni. K*^ respired. An energetic supporter of combustion, like thc 
raiioaUionwr. protoxide of nitrogen, gives rise to a feverish glow, cerebral 
acti^nty, to be followed eventually by a deep depression, the poisonous 
influence of tlie carlionic acid produi^d being exhibited. After a while 
the system casts it off, and recovers its condition of health completely. 



J 



£FFECT OF BA&EFIED AIR. 



183 



If there Lo an abstinr-Dee: from foofl, since the intro<Iaction of air br 
re^iration mica on wiliiout abatement, the body itself must . . 
undergo oxidation, lose weight, and emaciation occur. Its imtuaiusur 
temicacy to follow the diurnal variations of temperature be- 
come more and more strikingly marked as the proecaa of fitan'ation goes 
OOt and finally a rapid and unclicckcd decline of the beat ensues. Yet 
eren tlicn life may be prcscned by the application of sufficient external 
varmth, and from an extreme condition of attenaalion on animal may be 
rescued by (he use of food ; but for Budi a recovery the external warmth 
must 1« continued until there has been time for digestion and absoqition 
to take place. It', however, such an extraneous aid be not duly applied, 
the temperature of the star\'ing animal goca on diminishing, and he dies 
of cold. 

The doctruic we arc here incidcaling, that animal heat is due to oxid^ 
tion in the system, is still further strikingly illustrated by pn-^^ ^^ 
what might be termed stan'ing the rejtpiration. As cold is afiinngnrefled 
iolt horn want of food, ao also it is from want of air. In as- *^'' 
oending high mountains, the effect upon the system has been graphically 
cxprcBBed as '^ a cold to the marrow of the bones ;" a diiHculty uf making 
BHUcolar exertion is ex]>erieiieed ; the strongest man can scfirecly take a 
few steps without resting; the operations of the brain are interfered with ; 
there is a propensity to sleep. The explanation of all this is very clear. 
In the accustomed volume of air received at each inspiration, tlierc is a 
Ices qnantity of oxygen in proportion as the altitude gained is higher. 
Koncs can scarce be made to bum on such mountain-tops ; the air is too 
thin and rare to support them ; and so those combustions, which should 
go on at a measured rate in the interior of the body, ore greatly ro- 
daoed in intensity, and hence the sense of a penetrating cold. Such 
jonXDCys, moreover, illustrate how completely tlie action of tlie muscular 
Ajralew, and olso of the brain, is dependent on the intK)duction of air; 
and under the opposite condition of tilings, where men descend in diving- 
bcUSf though surrounded by the chilly influences of the water, tliey cx- 
petieooe no corresponding sensation of cold, because they are breatliiug a 
compressed and condetued atmosphere. 

The rrapinitory apparatus of certain animals permits a reduction in the 
anumnt of air introduced under exposure to a due degree of „, 
oold. Such animals are said to uybcmatc. At the com- ii.vi>Fni«tiiig 
ing on of winter their aflijiose tissues arc engorged with fat. ■"'"*'*■ 
As they pass into their annual sleep, the rate of their respiration falls. 
The laannot, which in activity will make 140 respirations in a minute, 
mskesDOWbut 3 or 4; the temperature of thclx)dy descends, and eombas- 
tioo of the store of fat goes on more slowly. Yet it does go on, for, toward 
r^ the animal has become very lean ; sufficient heat is disengaged to 



^mta^tV 



184 



COOLING AGENCIES. 



permit the blood slowly to circulate, and so barely to keep np the fimc- 
ttons of lite. If, however, the stock of material available for coxnbostiaa 
is iiiiiuHicicnt, tlie animal dies. 

Alllioiigh wc can not interierc with the rate of respiration, wc em 
Reducifon of »^*^ ^^^ quantity of air introduced into the system by icti- 
tprnp-Tsturci.^ ficial means, as in the operation of blood-letting; forthoa^ 
main ui..ri.ia artcr blood lias be<m dniwu, wo may muko I lie normal nnra- 
uaM, Ijpj. fyf respirations, 17 in a minute, and for each introduce 

17 cubic inches of nir, we have diminished the number of discs, whidi 
are the crirricrs of oxygen ; and, as the cxj>criencc of physicians in all 
times has shown, tlicrc is no method so effectual in reducing any umuaal 
or febrile lfnii>erature. So, iii like manner, in iVsiatic cholera, the marble 
coldness which t!ic body presents is attributable to the loss of fuocCioa 
of the discs, and tlic consefjuent abatement in the quantity of oxygen in- 
trod need. 

Thus far we have considered the means which the animal mechanism 
u tuniMn f possesses for rai^ng its own tcmpentaro ; it remains to show 
Kdncin^tbo how it can also regulate it. For any thing that has thtis&r 
temtxniun.'. j^^^ ^^^ ^^ ^j^^ contrar)'. the combustions or oxidaiiona 
which arc continually going fonvard should establish a constant riae, and 
there must therefore be somo principle of r>2straining sucli a riao irithia 
due bounds. Considering also tlu3 incessant vicissitudes of atraospheric 
tempeniturCf a constant degree could not be maintained unless the sys- 
tem possessed the means of depressing as well as elevating its beat. 

That tlte means of regulating the heat are purely physical, wc ahooM 
EO^i o( nv- expect for many very obvious reasons. Economy of beat is 
M^moijaci- accoinpUsbed bj non-conducting materiat On this princi- 
ibititr. pie, hair, wool, and feathers act by excluding the contact of 

the atmosphere, their low conductibiiity being brought into opcratioD. 
In nrnny cases, the manner in which this is done is clearly intentional 
Thus the down whicli is placed on tlte breast of a water-fowl is to screen 
off tlie chUling influcnco of the water, which is there cbieiiy felt as the 
bird swims on the sur^we. The deposits of fat in whales, their blubber, 
at once atfords a pmtection through its imjicrtect coodnctibility, and is 
alfto a store of combustiblo material for the purpoae of respiration. 

The chief cooling agencM* in aninuis are. 1st, Radiation ; 2d. Loss 
Qmmwirmti- of beat by vanning the expired air; 3d. Loss by contact of 
in««c«Ktn. the cold external air ; -Itb. Evapontio& The drcnUtion of 
tikfi blood tends to establish ao interior egnaliiation, so tliat local ^-aria- 
tions are soon obliletatcd ; fiar« thnwgii whatem put the blood may flow, 
it attains tbe lempentuie tberaof, and, pMsing in sncoenion from part to 
part, equaHxea the heat of alL 

It would be osdcss to oficr any proof that a Urmg beia^ liko an in^ 





I 



imto 



:uc mass, lose* or cabs heat, us the case mav he, hy radi- ^ 
n. hincc, however, m niaii, the tcin|K;raturc is usuaiiy 
iiigKcr than tluit of the surrounding lucilium, the re>*ult of tliis action is 
that coolini^ tikes place. With regard to loss of heat by wanning the 
expired air, it may be obsen'ed that, whatever tijo temperature of llic ex- 
temal air may Iw, it is raised to that of tlie lungs after it lias been brought 
the respiratory jwissages. This constitutes, therefore, a cooling 
of variable power, for the loss will be greater as the external licat 
lower: if the atmospheric temperature rose to 98°, loss in this manner 
would cease. Recalling wiwt has been said resiwcting the mode in which 
'«ir is intxuduoed, it is plaiu that this loss will chie6y fall ncatKlrcBtu 
rltpon tiic nasal passages, the trachea, and larger ramilications ilivtixijinuiair. 
of tlie bronchial tubes ; for, by the time the volume inspired has made it3 
way licyond that limit, its temperature must be nearly that of the body. 
The contact of the cold suiTOuudiug air, and more particular- ^(^^(^pi „f u„ 
ly of currents which may be occurring in it, act chiefly upon surrouuding 
[tbe ftkin, and it is in preventing this toss that clothing be- 
'Oomcs BO efficient. The ditl'c-rcnce we so frcrpiently notice between llic 
indications of the thcnnoractcr and our own sensations arc, fur the most 
dependent on these currents. A ten)|>eraturc of 50"^ below zero can 
sustained without much inconvenience if llio air is pcrii.*ctly calm, 
hat not to if there is any wind. Of all the cooling agencies, cvajmration 
Is, however, by far the most energetic. From the skui and ^.^jj ^ 
the air cavities, large quantities of the vajjor of water are ex- cmporwioo of 
Italed. As the cxlermd heat ri?ei', the sudorijmrous lubes act *'"*' 
with increased energy, and jxjur out their excretion as drops of sweat 
'&ster than it ciui he removed. Their length lias been estimated at 28 
inilea. Since, atlhe temperatarc of the body, the heat of clainlicily of the 
vapor of water is 1114^, thift continued vaporization from the skin and 
loiigs L3 otie of the most powerful sources of refrigeration. 

It may be well to direct a closer attention to the special action of the 
passages and skin as concerned in these cooling process- v^rui^utv io 
efl. The diurnal loss of water, by both organs conjointly, is ihe Kciion'of 
osually estimated at 3^ lbs., of which the pulmouar}' cxha- ^'^' °' 
lation coni<titutes about one third, and the cutaneous about two thirds. 
Tho skin acts iu a variable manner, losing more or le^s water as the ex- 
ternal air is dr\'^r or more damp. The removal of water tlicrcforc bc- 
a complex operation, in wliich lliree different organs are concerned 
skin, the lungs, and the kidneys. Of these, the skin acts uietcoro- 
;ically and variably, as has been just remarked, and the rci^piratorj' or- 
gans for the most part uniformly. But since it is requisite, in the nor- 
mal operations of the system, that the diurnal average of water shoold be 
Ted, the variable action of the skin throws a variable action 



BALANCE BETniXN UEATI>0 ANU COOUXO. 

Tturioas nf. '^^ kidncvs, foF thc exocss that the skin can not cvaponte 
tkinurthrkitl- must be Rtraincd ofT by thcso nrganfl. In this rrgui-d tk 
"*-'■ kitlncys act, therefore, vicariously for thc skin; and in bot 

weathcrr, when tho cutaneous losMst arc great, but little unnc is diBchai^il: 
but in cohl %vejillier, when tlic cutamwua loss U Jiininished, |]ic tjiiamitr 
of the urine is increafte<L 

I tliiak, liowevcr, tliat as regaidq thc respiratory organs, a disliocUoo 
^ . . should be made in their mode of action. In rcalitv, tiMT 

tha mir|>a^ opcTstc in a doublc wny. 1st They act, so for as the nasal 
"*'*■ passages, tho tracheii, and hu^r ramifications of tho bron- 

chial tubes are concerned, meteorologically, and tlierefore variably, for 
the introduced air possesses tho existing atmospheric temperuturc ; is ti 
one time warm> and at another cold ; yet, sinco it always leaves these 
|>assaj;c3 at 94^, it removes from tlicir surfaces sometimes less and S0ID^ 
times more heat ; but it is not so with tho action going on in the u^ 
cellsv the temperature of wliidi, and of the air they contain, is ulwtTS 
uniform ; and as water vaporizes into them, it must always do it at a uni- 
form rate, and remove as its caloric of elasticity a uniform amount of 
heat. I therefore decompose thc loes of heat by the respiratory orgau 
into two portions : one, which is constant, and taking place in tho cells; 
the other, varialJe, occurring In the large air-ways, and, being meteortH 
logical, coincides in *hij respect with thc cutaneous loss. In conside^ 
ing the diseases of the respiratory organs, it is well to keep this distino* 
tion in mind. 

Thc cstabliHhment of the e>]uilibrium of temperature in an animal u 
ItaUnra itc etfected by the nmluol ojH'iration of the ht^ating and cooling 
in^'oiMlwolinff »irrangements. More or lews heat, as the syRtcm requires, 
«rTaus«mciiu. may be furnished by promoting or retarding thc oxidation 
of respiratory material ; and since a living being, like an inorganic mass, 
is subject to ever}- external influence, its temperature tending to rise or 
fall ns diumnl, or annual, or seasonal changes may be, these, aa well ai 
Ellminitlnn of 1*3 own interior variations, arc held in check by tho cooling 
l<Kiilvflriaii"n* ^j warming powers it can exert. Local diflercnccs within 
tion of the itself are eliminated in an indirect, but still very cflfectual 
Llood. manner, by thc circulation of the blood : and, considering 

the range of ATiriation to wliich it is exposed, and tlie frcq^uoncy of the 
changers tho required equilibrium is admirably secured. 

I have reserved for a more siKwial and ]>rominent consideration the iu- 
C«ntroi of iiw '^^^^"ce which the ncnons system exerts over animal heat, 
Dprrotu «yii. sinco it is upou tlus that many have been disposed to deny 
tho great truth that the heat of tJie body arises from oxida- 
tion. Thpy say that it is procluccd by llic nerves. Even a mental emo- 
tion gives rise to disturbance of temperature, and thc face may be cover- 



lOTXUENCE OP THE NERVOrS STSTEiT. 



187 



with blushes. Jloreover, as exi>eriment8 have proved, on catting a 

^'e the tcmperaliire of the parts it supplies declines; on injuring tiic 

t nen'c centres the temperature of the whole system Iowcth, oven 

>ugh artiticial respiration may be kept up. In cases of paralysis, the 

peraturc of the disablod part may be very much lower than tliat of 

Ihe eound. A paralyzed ann has shown a surtaco beat of 70'^ only, 

■rhile the sound one has been at 92'^. It is also said of decapitated aiu- 

IDbIs that ibey cool (juicker when artificial respiration is kept up than 

when tlicy arc let alone. 

AH this may bo very true, yet it is very tar from proving that the 
lerrca arc the generators of animal Iieaf. The engineer of a locomotive 
regulate the sjrccd of his train and control the production of steam by 
Itrowing more or less fuel on the tire, or by supplying it with more or less 
but docs any one impute the production of the heat to him ? If 
accident should throw him off, thereby establishing a sort of analogy 
ecu liis machine and the decapitated animals we ba%'C referred to, tbo 
that would soon ensue, and the dying out of the tire, would by 
meuis prove that he made the heat 1 

And 80 witli the nervous system, its function is not a generative, but 
controlling one. It determines in what way the combustive or oxidiz- 
ing actions shall go on, but that is a totally ditferent at&ir from forming 
liiD heat 

\ Before Bi)eci!ylng more particularly tl;-:; views I entertain on this sub- 
[Ject, I will remark, that the most supcrlicial consideration satisfies us 
that oxidation in the system goes on in a regulated way. There is not 
jsn indijyTiminate attack made by the arterial blood on whatever is next 
fore it, but those particles only arc removed which the needs of the 
require. This tbereforc implies some overriding or supenntcnd- 
agency, which can save one atom from destruction and surrender an- 
other. The portion assaulted may, to all appearances, be identical in 
physical aspect and chemical constitution to an adjacent one tliat is pass- 
ed by. There seems to be an arrest or suspension of atbnity in one case, 
Ind itff ready satistactton in the other. 

I Ti»crc arc some well-known facts in natural philosophy which throw 
a flood of light on this obscurity. If a piece of i^urc zinc phvrfrai uni- 

Ibe phiced in b {tIoss of acidulated water beside a piece of ««"• **> ^^ 
r^ * , ° , , ' .^ , TOtiirelortb* 

copper, ao long aa the metals arc kept apart no action wliat- asrvaai i^*. 

ever ensues; bat if a conducting thread is laid from one to **^' 

tliQ other, the zinc instantly begins to oxidize, clouds of hydrogen goa 

^^nbbles rise from the copper, and the thread becomes at once red-hot and 

■bnetic On litling the communicating thread all these actions cease; 

ron restoring it they instantly recur. We think wc explain them by sny- 

iag that they are all due to the decomposition of water by the zinc Uut 



188 jOLOTXopisu or osaAxic bodies. 

why was tlic zinc passive wlitrn alono, and why did it assume this activ- 
ity wlien merely touched hy another roetul? Does not all this son'Olo 
show that suhstauces may be, ati it werc^ In & quiescent state, and on tin 
npplir^iion of what niay perhaps seem the most insignificjuit caase,inay 
suddenly assume activity, and forthwith satisfy their chemical affinities^ 
There is nothing in tho graduated oxidations going on in the system 
more obscaro or more unaccountable t)ian the phenomena of a simple 
Voltaic circle. Their eflects arc almost parallel. 

All elementary substances apjicnr to have tlic quality of assnming active 
Alloti«i4mor aiid passive conditions. Carbon, moreover, presents many 
****** intcnnediate forms. As diamond it is extremely incomba*- 

liblo, and is set on lire with difliculty even in oxygen gas; as lampblack 
it will kindle B|K)ntaneouely. ^^'ilh these dificrcncca in its relations with 
o-xygcn, it also exhibits great variations in its optical, cajorific, mechan- 
ical, and other properties. These transitions of state may be induced by 
various causes, esjjocially by the agency of what arc called the ini|y)n- 
dernblc principles, as hy rise of temperature, ai:d exposure to the sun- 
light. Thus, in the case of chlorine, 1 have shown that, thoo^i it re- 
fuses to combine with hydrogen so long as it is in tho dark, an exposure 
to indigo-colored light will cause it to unite with explosive energy with 
that substance ; and these peculiarities are retained by bodies when 
they go into union with each other. Thus there are two forms of phos- 
phorus, the one active and shining in the dark, and therefore readily oxi- 
dizable ; the other passive, not shining in the dark, and with therefore a 
less affinity for oxygen ; and these severally give rise to two varieties 
of phosjilmreled hydrogen, which, thougli having the same composition, 
yet dilTcr in this respect, that tlic one containing the active form of phos- 
pliorus is sjwntancously combustible in the air, but the other, which con- 
tains the passive fonn, is not spontaneously combustible. Phosphorus 
is thrown from the active to the inactive state by mere exposure to the 
more refrangible rays of tlie sun. 

The pro|)ejtie3 here spoken of have been designated by Berzelios as 
Anotro|.i«m of ^'^^ allotropism of bixlies, I have endeavored to prove that 
orgauUwi boJ- allotropism is the true cause of many of the obscure facts 
which we meet with in tho animal mechanism ; for it is very 
clear that something so modilies the relations of tho tissues to oxygen 
that they are not indiscriminately destroyed by it, but these parts yield 
in a measured or regulated way ; and since, in inorganic substances, tlie 
influence of tlie imixtndcrables can compel the assumption of an active or 
passive state, there is nothing contradictory in imputing to the ncr\-oufi 
system a similar power. 

In this manner we may therefore conclude that, so far as tissue dfr- 
fitruction is concerned, the ncnotis system possesses a governing or con- 




OP SECRETION. 



189 



trolling power; timt iy kcepuij* ])ort3 in Btntes answering to the pnssive 
and active comlitions of inorganic chemistry, it can suspend the action of 
the respired oxygen or permit it to take effect. Tliis controlling power 
is, however, altogetJier distinct from a generative one, and all the heat dis- 
engaged ia due to oxidation. It is also possible that not only an^ tlioso 
' fltates of activity or ])as3ivity impressed on tlie tissues by the agency of 
the Dcrves, but als^) ujwn the respired oxygen itself, since that gas is no 
cjtccption to the rule; it also exhibits allolropism. Its passive state is 
Priestley's oxygen, its active is Ozone. lu its transit from the air-cells 
into the blood it may experience such a cliange, and hare at ouce com- 
municated to it a high degree of activity. 



CILVPTER XI. 
OF SECRETION. 



BRSOrS, MCCOL'S, AVtt nEl'ATX BBCBCnOKS. 

OAfM^ t>/ S**Tttien.— Tsp« »f uttrtting Mteiiam»m.—FiUraHtm md CeU AeiiM.—O/ Serevt 
UtmbroMeM trnd thtir ^teretion*. — Q/' J/inv«m Mti^roM* <ad fkeir S^crttioia. — 0/Utpativ Se- 
trttiMu. — The fJoer; iU Deve/iymtnit and Strttrturr. — Sotirct^ l^tumtit^, Com/msilioa, F/mj; 
amit f'iovr o/(ke UUe, — Existence <(f'Miarji hujreilivnU in lAelitoml. — /Vof/wfttin 'i/S*fjar and 
ftal n t&t Lirrr. — 0MMtjtJi of' the filawl-frlh in it. — Cewrtd Svmmary of the four-fold ArAioa 
Q^cAfl Liprr: it pr^dmtx Svgar and Fat, tiiminatts Bile, it the Heat (tf'thejinai Jjtstntction 
of old lUood-ctUM^ a»d q/ the CompietioR of new One*. — 0/ thi dnctUts GlaiuU. — ThtSpUem 
ita f'toKtivtu. 

Two classes of substances occur in the blood — the products of decay 
and the elements of nutrition. The equilibrium of the system requires 
that the former should l>c removed and the latter appropriate*!. 

The primary object of the function of secretion is this dii^iiLiasol and 
appropriation, and thejefore, through the latter duty, secre- oi.jteior«c». 
tion IxTomns eoiinected with nutrition. '■**"• 

The elementary type of a gland or organ of secretion consists of a sae, 
on the interior of the wall of which a network of arterial raniifi- tvp* of a 
cations is spread; tins delivers its blood into a sirnilur network kI'"'J- 
of veins. The matter which the gland is destined to separate tKJzes 
fipom the arterial capillaries into the interior of the sac, and is delivered 
thnragh the neck or mouth thereof, which may be sjxiken of as the duct. 
It will be presently shown tliat the material which thus finds its way 
into the interior of the sac is not fabricated by that organism, bat is 
brought to it pre-existing in the aflluent current of arterial blcwd. As 
our knowledge of the functions of glandular structures becomes more 



t 



190 TicARiora SEciurnoy. 

precise, the has and Icjw docs it appear probable that the secretctl matter 
is in any way engendered by the glaiid itself. 

Since, with the exception of the lungs, which excrete carbonic acid and 
Chuiic* in ^TO' *** water, all the great glaiid.s remove the materia] ther 
pUnduiar are concerned with in a state of Hquid solntion, it follows of 
*"^' necessity that the blood of the artcn,' snpplying the gland, and 
that removed by tlie vein from tlie gland, difter in two respects : Ist In 
the peculiar material oonstituting the Bolid secreted: and. 2d. lu tbo 
quantity of water. From the hitter cause it must follow that the venous 
blood will ha^-e a p'latcr gpissitude than the arterial. 

Thi3 elementary or typical fonn of a gland is but very little deported 
from in those cases in which the sac is elongated into a tube ; and eren 
wheni this has been extended to an exaggerated degree, the cs.'cntial 
principle of action still remains the same. 

From tbo constancy of aspect which glands present, wc might be led 
Influfttr* of at first to BuppoHti that their peculiaritic? of construction de- 
bjvidJ^'ao- **irn'i"c tbelr physiological action, that the liver secretes bil^ 
tioa. and the kidney urine, because they have the spexnal organ- 

ization wiiich i-'* nccdtid for eucli purposes. Such a supposition, liow- 
c\'cr, has to be received with much limitation, as is proved by numlxr- 
less cases of vicarious action. Thus, in morbid difficulties of the liver, 
the skin will discliarge its duty for it in the elimination of the bile; and 
in derangements of the kidneys, the maminar}' gland, the mucous mem- 
brane of the nose, or even tl»e Btomach, will disuluir^i? urine, Constniet* 
ive arrangements Ilivc therefore for their objectthe facilitating ofaai^erft* 
tion, but they do not produce it. Thus the liver is far better fitted (of 
separating bile, or tlie kidney urine, than is the skin for c.ich of these re- 
spectively ; bat if they become incapacitated, the akin ir> able to act viefr' 
riously for them. 

Though such vicarious action has been denied by Foroe physiologiJtB 
C«nnMiiafi of as being totally incompatible ^vith Rimtomical indications, ft 
"tiw^uu^A- "">''*? profound conception of the law of development of thesa 
opmarit. structures nmy satiHty us that it is in reality a physiologicil 

probability, apart from the evidence we have often derived from interest- 
ing instances of its actual occurrencot It will be seen, when we treat of 
the primitive appearance of the different secreting organs, tliat they are^ 
in reality, all evolved, as it were, from a common surfaoo or membmne^ 
tliat this primitive surface diacliarpcd, though perhaps in a confui«ed way, 
all their functions collectively; and that in dcvciopraent the niling idea 
seems to be the eeparating out, or localizing upon a determinate spot or 
region, structures which should have the duty* in a special manner at- 
tached to them, of removing this or that partiadar substance, a central- 
ization or concentration of action thus occurrinjf. There is therefore 



raTRATlOy AND CELL ACTIOK. 



191 



Botbing extraordinary lliat, under iho pressure of circumstances, one of 
the special structures should, in an imperfect way» resume the aetioa 
wiiich it once enjoyed, while it was j'et a part of the common structure ; 
but, however this may be, the cases of vicarious action arc too numer- 
ous and too well autlicnticated to admit of any doubt. 

Though these vicarious actions may be in a certain degree impei-fect, 
tbey are of the highest importance pliysiologically, since they indicate the 
ttne nature of tlie function, and place the in6ucnce of structure in its 
proper attitude. 

The separation of material from the blood may, however, for the pres- 
ent, be considered as conducted in two different ways ; Ist, by llltration ; 
2d, by cell action. 

Secretion by filtration is, of course, a purely physical act. The trans- 
udation of water cliarged with saline substances, or with more Sfpamina of 
or less of albumen, seems to imply nothing but the escaj>c of "/"'Jj^oJ^y 
pteK^xisting bodies tlirough pervious or porous membranes, titration. 
Sach a result is presented in the case of the lacliryirial gland, the duty 
of which is to accompiisli a dt-finite mecJianical ojicration for tlie eye in 
koepuig the coniea clear and transparent. This mcclianical function ia 
a^in (observed in the case of the serous membranes, and parlitularly the 
synovia] ones, in wliich the relief of friction of movable parts sccnis to be 
iho object aimed at. 

As long as tho material secreted clearly pre-exists in the blood, it is 
necdlcsjf to refer secretion to any other principle than the simple one of 
transudation or filtration. It would be unphilosopliical to sup]X)se that 
tlws WhrjTnal gland exercises any pro(jerty for the formation or produc- 
tion of water when by mere transudation copious supplies of that sub- 
stance can be obtained from the blood. 

But pccrction is, moreover, |)erhaps connected with cell life. On tho 
upjicT part of the intestine of the young chick, a few cells s«cretion 1.7 
make their appearance about the fourth day of incubation. «;il«cUon. 
Tbey are eventually recogni7.ed as bile-containing cells from the color of 
their contents. As the process go<^5 on, the sjwt they occupy buds off, 
as it were, so as to produce a blind pouch. This oflahoot, with its ex- 
h tenor cells, is eventually, wlien perfect development is reached, the liver. 
■ Seeming organs of this glandular class, and also mcmbranc.<>, possess a 
V g e n era l analogy: they consist of a structureless basement mcinbrauc, with 
cells upon its surlacc, and a supply of blood-vesaels. The cells are not 
penistent, but lead a ycry transitory life, apparently elaborating the ma- 
terial with which they are charged, and then undergoing nipture or dcli- 
quesGenco. 

Our conclusion respecting the mode of action of secreting cells turns 
altogether upon the evidence of the power they possess of preparing ma- 




192 FILTRATION AND CELL ACTION. 

fcriid which did not preexist in the blood. Thui^. it* it should lie shown 
tliat, under normal circunistanctis, the elements of bile arc not found in the 
blood, the inference might he drawn that the hepatic cells display a com- 
biniiig, or, as it were^ a preparing power; and so likewise in the ca?c of 
other secreting ceUs ; but the weight to be attached to such evidence is 
greatly aiToctcd by the consideration that the action of each gland orse- 
DlfflcnitvoMe- crcting Apparatus masks what is rcsUy going nn in the sys- 
iTwcSu I" *^'"- ^' *^ possible t!mt wc may be scarcely able to di?cor- 
Um blood. cr the traces of substances in the blood, and yet a tcudcucr 
may exij^t for their accunmlatlon to a great extent. Tims thery can he 
no doubt that urea would abound through the disintegration of the roas- 
cular stmctiires, and the use of nitrogenized food, if it were not for the 
action of the kidneys. It is the vcrj' |)erfcclion of that action which so 
diminishes the amount in the circulation as to prevent us, c.\ct:pt with 
difficultvt from detecting the presence of the ingredient. 

Nor is tliis all, for it ouglit to be rcmembci'ed that many of the prod- 
ucts of secretion arc substances undergoing retrograde metamorphoses, 
and have therefore, as it were, in themsclres, an interior principle of 
change. It is conceivable that things which did not pre-exist in the 
blood may yet ootnir in the secretions, coming there, not through the 
agency of cell-life, but liecjiuse of tlic downwanl conrsc toward an inor- 
ganic condition through which the secretion is spontaneously passing.. 

Of the more prominent substances in the chief secretions, many indis- 
putably pre-exist in the blood. Urea, choleslcrinc, casein, are examples. 
Wherever this occurs, tlie removal is unqnestionably duo to mere filtra- 
tion. AVTiy should it be supixiscd that tlic cells of the kidneys Iwve any 
duty of combining material presented (o them into urea, or those of the 
lircr into cholcsterine, or those of tlie mammary- glands into casein ? As 
our methods of examining the blood become more perfect, this formatiTc 
or grouping action, once so largely imputed to the secreting ccltst be- 
comes more and more rcstriclcd. 

The cases in which the influence of cells is indispntablc arc those which 

Omdiiion* i.f *^^*^^ ^^ "*^ combinations of progressive metaniorjdiosis. Of 
fitraiion and thcsc, the moflt Striking instance is the preparation of the sper- 
otcvW aciian. ^^^-^^ jj^^jj^ Perhaps we should not be very far froni the truth 
if we considered all those secretions in which the materials arc in a state of 
retrograde metamorphosis, or in a de~scending career, as arising by mere 
filtration, and tbo?c which are ascending to a higher grade as due to cell 
agency; between the t^vo there being an intermediate class, the phase of 
which is stationary, and in which cells may or may not bo necessarily 
involved, as, for instance, tiie transmutation of one fat into another, or 
the preparation of sugar from albumenoid bodies. 

The apparatus for secretion is generally conveniently ticatcd of under 



M 



SECRETIOJrS OF SEROrS KCEKLBRAXES. 



» 



I 



twohe&ds: 1st. Kcmbranca, sucli OS the serous undniucons; 2(1. Glands, 
as the liver, kidney. This division is, however, not founded cither on 
Btmctiiral or functional ditferenccs, and is to he prescn-cd merely for tlio 
sftkc of convenience. 

A secreting membrane consists essentially of a tunic of connective tis- 
sne^ affording a nidus for vessels und nurses. UjM>n tliis, in the opinion 
of many anatomists, a ihin basement membrane is laid, the existence of 
which is denied by others. Upon the surface of the basement membrane 
there is a layer of cells, the form and arrangement of which differ in 
diflcrcDt regions. In some places the cells arc flat, in others cylindroid. 
Their duration is tcmporarj', one brood succeeding another from germs on 
the basement membrane. Tlio supcriicia], and, tlicreforc, the ohlcr cells, 
desqnamate or dcliqucscCt and are replaced by others from bcnc^ith. It 
ia asuAlly said that the serous membranes, with the exception -^. 
of the peritoneum, arc all closed sacs, the pcriloneum being i.rnnwujd 
perforated where the timhriated extremities of tlic Fallopian * r»ccreuon. 
tabes open into the abdominal cavity in the mammalia, and in fishes 
through the lateral anal openings. The generality of this view is now 
called in question, both as regards the synovial sacs and bursa? mucosa.% 
whicb all belong to this group. Thus Kolliker regards the synodal 
Ptmctnres as tubes open at both ends, and attached by their edges round 
the articular surfaces of the bones. 

However this may be, even tlic peritoneum is practically a shut sac 
Accumulations of water witliin it do not escajx: tlirough the apertures of 
the FaUnpian tnbcs, nor can air bo injected the opposite way. 

The fluid exuding from the serous surfaces is a dilute albuminotis 80- 
Intion, more dilute as it is presented in tlxe ventricles of the „ ^ . . 

, . , , . 1 . , . . . Scroui fluid*. 

bram, and more concentrated m the synovial cavities, its con- 
sisteacy in the latter case being such that it may sometimes be drawn 
out in tenacious thrcadii. The mcclLauicol qiialities of these various ex- 
udations permit a certain freedom of motion in the parts to wlueh they 
are applietl. Thus the secretion of the peritoneum facilitates the mov&- 
menlA of the abdominal viscera ; those of the pericardium and pleura, of 
the heart and lungs ; those of the synovial membranes and bursie mu- 
cosjp^ of the joints and tendons. 

The nature of serous secretions may be illustrated by the cascJi of 
ilaids collected from the abdomhial and thoracic cavities, &c They 
are usoally ^ a iaint yellowish color, clear or turbid, reaction alkaline, 
and flometimcB containing so much albumen as to coagulate readily on 
heating. 

N 




194 CONSTITUTION OF SEBOUS FLUIDS. 

TABLE I. 
Flmd of Atcitet. {From Marehmd.) 

Water. 9">2.30 

Albumen 23,80 

Urea 4.20 

Chloride of sodium 8.10 

Carbonate of soda 2.10 

Phosphate and traces of sulphate of soda 0.60 

A viscid substance P-W) 

lUOU.OU 

TABLE n. 
Aadtes tcitk Sf^tpnratiam of both Kidaeift. (From Simon.') 

Water 978,00 

Fat containing cholostcrino 1.00 

Albninen^ 8.40 

Alcohol extract 0.80 

Spirit extract 1.70 

Carbonate of Boda and phosphate of lime 1.20 

Chloride of sodium and lactate of soda 6.80 

Urea 1.20 

Loss „ 1.40 

IUUU.00 

TABLE m. 
Pleural Effusion. (From (Suaon.) 

Water 934.72 

Fibrin 1.02 

Fat 1.0.-> 

Alcohol extract, with salts 1.35 

Spirit extract, with salts 10.64 

Albuminate of soda 17.66 

Albumen 81.00 

Fixed salts 9.50 

Gain in analysis 7.14 

lUOO.OO 

To the alx)vc may Ikj added tlic following interesting instances of fi 
of hydrocele, in which attention should be particxilarly directed to the 
ciurence of cholcsterine and other bile constituents. In the case ■ 
sented in Table IV., the fluid was observed to sparkle when shaken 
consequence of the numberless crystals of cholcsterine : 

TABLE IV. 
Fluid of Ilifdroctle. (From Simon.") 

Water 860.00 

Cholestcrine, with a little marj;ariue and oleic acid 8.40 

Albumen 48.30 

Albuminate of soda and extractive matter - 6.88 

Extractive matter soluble in alcohol 2.30 

Chlorides of sodium and calcium, a little sul- > 

phato and traces of phosphate of lime J '" " 

Phosphate of lime and traces of peroxide of iron... .70 

Loss O.tK) 

1000.00 



PRE-KTISTENCE OP SECKETED ritODrCTS. 



195 



TABLE V. 
fUd q^llydrooeie. (Fnm HrStr.) 

"Water 919.20 

Albumen » &&.00 

FfM f«t l.CO 

Soda aoa|i, liJIipTiiiein, hnunato-globolLn, dissolved J . « fu, 

tucmolin, and cxtniclive j 

Fixed salts l.m 

lUUO.lK) 

TABLE VI. 
FUid 0/ ns<ifwxk, iFromlitUtr.) 

TYalcr 906.36 

Albumen 60.00 

Fat containing cholcarerine 0.23 

E>:tmctivo inntterK, Ipiliphiieiti, »odji soap 24.04 

Fixed Baits, chiufij^ diloride «f sodium 9.S7 

1000.00 

TABLE Vn. 
Sj/wcialFimtL {From FrtritA*.) 

Water 948.00 

Mncus oud G[uthclitiui C.OO 

Fat 0.70- 

Albumen and extroclive ,„ 85.00 

Salt* 0.00 

Low 2.30 

1000.00 

I liave introducod tlieac tiiblcs not only for the purpose of exhibiting 
lUe nature of the 6u.id yielded by membranes of tlic serous Proaucuofw- 
group, Intt also for (he sake of llie important evidence tliey 5^in^'\^^''' 
offer aa regards the function of secretion itself. In tlie in- l>lood. 
fancy of physiology it was universally believed that the special function 
of each gland arose from its jicculiarity of construction ; that thus, by the 
Ii\'er, out of blood in which they did not pre-exist, cbolestcrinc and its 
flilied bile compounds were made; that thus, by the kidney, nre.i was 
formed. Kven in more recent times a modification of this doctrine has 
prevailed, and to the cells of which glands are so largely composed, the 
duty has Ixien attributed of forming special products. In this way, we 
still constantly speak of tlie bile-secrcting cells of the liver; hut tlic pre- 
ceding tables indisputably show that these vor}' compounds, cholcster- 
inc, bibphaein, urea, etc., may make their appearance in distant places, 
oozing irom surfaces wholly devoid of the sup}>08ed special mechanism. 
Tn cases in whicli there occurs structural degeneration of the kidneys, 
for instance, urea at once makes its appearance in unaccustomed places, 
as though, when tlie readiest avenues through which it might have es- 
caped have failed, it bursts forth or oozes out at the weakest point. 
With such results, the idea of leakage or straining seems to be inscjiara- 



19G OF ELECTIVE FILTBATIOX, 

h\y connoetetl ; and, moreover, an enlarged view of the operation of cU 
life seeiDS tu indicate tliat the general action of those organisms is'.o 
produce a formative result, the grouping of amorphous into orguuied 
material, and the elaboration of that material into more complicated and 
higher forms. Hut man3r of the most im^x)rtant coustltuents of the va- 
rious secretions are indisputably tilings wiiich arc on tlie downward ca- 
reer, fast passing to the inorganic state. 3[any of Ihem, as presented in 
the bile or in the urine, run through a scries of spuntaneous changes, 
which end in the appearance of truly inorganic bodies. For the fabrica- 
tion of such substances, half inorganic themselves, it is scarcely to U' 
thought that cell life should be necessary; and these, with many otlic: 
such considerations, recall the observation I made a few pages back, tlut 
the more profoundly wc study the composition and constitution of se- 
creted tluids, and the more accurately we understand tlie function of se- 
cretion itself, the less are wc disposed to invoke the agency of cell lite, 
and to rely the more on the ordinary meclmnical act of strainagc 

That the different secreting surfaces exercise an elective cUmination on 
KlMtira (iitra- materials existing in the blood, some i)ermitting tlic esc^ 
nan. of one, and some of another in^tedient more readily, maybe 

demonstrated irom their action on saline substances purposely iDtrodncod 
into the blood. Thus the iodide of [)otassium was delected by Benuid 
in the suliva, j>anereutie juice, and the tears in less than one minute, 
but in the urine and hilc not until after an hour. Tlie fcrrocyanido of 
potassium could be recognized in tlic urine in seven minutes, but not at 
all in the saliva. In like manner, cane-sugar and grape-sugar appear In 
the secretions of the kidneys and liver, but not in those of the pancreas 
and salivary glands. The lactate of iron, injected into tlie veins, fur- 
nishes no iron to the saliva, but both iodine and iron can be recognized 
in that secretion after tlie administration of the iodide of iron. 

Upon the whole, we may ihcrcfiti-o conclude tliat very many substances 
are strained from the blood in whicb they naturally occur by membranes 
and glamls, which, from the circumstance that they arc of varioofl con- 
struction and ]x>sscss a ditlcrent physical nature-, tan better adapted, some 
for the removal of one, and some for the removal of another comjiound. 

Among secreting surfaces the mucous membranes arc usually cnumer- 
Of mqroin atcd. Strictly speakirg, however, tliey arc scarcely so ranch 
*nTi'hc*r«m. »ccc*^"6 surfaces as the seat of numberless sccroting organ- 
tioa. isms. They line the interior of the digestive, respiratoij', 

urinary, and generative apparatuses, and ore characterized by e:£trcme vas- 
cularity. In structure they consist of several different layers or regions, 
the undermost txting submucous c^ular tissue, upon which is spread tlie 
proper mucous membrane, containing couucctive and elastic tissue, which 
affords a nidus for blood-vessels and nerves. Upon tliis is the basement 




■pnoPEnrrEs of kccts. 



197 



t 



membrane, covered with epithelial cells. In many regions this componnd 
Btructiire rises into elevations, aa in the intestinal villi, or sinks into do 
pTCRsion.s as in the follicles. 

The epitheUul cells arc of different kinds, sometimes flat, giving origin 
to tesselaled or pavement eiiithelium, and sometimes cvlin- 

... , ,,.,,. n ■ . 11 I EpitbcliiilceJI*. 

droiUf each cell, in this case, being set vertically upon the 
iMsenient membrane. In many instances, the cylindroid nucleated cells 
are furnished upon tlicir ontrr oxtrcmity with vibrating cilia, constituting 
cilintcil cylindroid epithelium. Both forms of epithelium, the tesselated 
and the cylindroid, coexist in glandular duets. The origin of the cells 
is in the basement motnbrane, from germs arising there ; and as the older 
and therefore supcriiciul cells exuviate or deliquesce, new ones arise to 
take their places. 

After what has been said, it is not receasary to give a detailed do* 
scription of mucous surfaces farther than to state that from rpoperti,.j 
ibcm there is furnished a viscid, gtalry fluid, of different shades ofi^uciw. 
of color from white to yellow, denser than water, and insoluble therein. 
Examined by the microscope, it contains granuUr coqmscles .and epithe- 
lial cells. Its reaction is alkaline, and its proximate constituent is a sub- 
stance to which the name of mucin has been given. Derived from dif- 
ferent source-s, as the nasal, bronchial, and pulmonary surfaces, the in- 
tcstimtl canal, and the urinnr}' and gall bladders, it exhibits spcciHc dif- 
ferences. Its quantity is often greatly increased by morbid causes, as, 
for example, in catarrh, its comjiosition likewise varying at different 
stages of the same disease. Its use, for the most part, seems to be the 
|nx>tecIion of the delicate structure which secretes it. In some positions, 
as in the intestinal canal, it likewise probably acts in the way of rcUcv- 
ing friction of the substances passing over surfaces. 

(}f 8*^crctinf/ Ghtnds, — The typical form of secreting cell-gland is a 
single cell, with its nucleus at the lower end, the other end simiJeMc-iikii 
having beeomi*. o^wn by deliquescence or dehiscence, and thus feU-feOauJ. 
constituting a sac. From the nucleus thus situated at tlio end of the 
cavity broods of young cells arise. These become more pci-fcet as they 
advance towanj the mouth of tlie sac. The outer wall, and esifcciaUy 
the region of the nuclens, is furnished copiously with blood-vessels. 

Of such structures, variously modified, the different glands are com- 
posed. We sliall now jjroceed to the description of the more imjiortant 
of these, as the liver, kidneys, mammary gland, &c., again impressing 
the remark tliat, though all tliese glands arc the seats of myriads of cells, 

I cell life is for increased organization, and secretion is in many instances 
nothing more than filtration or strainage. We shall endeavor, as the 
occasion arises, to bIiow, in the case of each gland, wliat part of its action 
b due io cell influence, and what to such mechanical permeation. 



198 



DEVELOPMENT OF THE LIVEE. 



_< I- , 



OF THE LU'ER. 
Tlic firat nppcnrancQ of a Ijile-socrcting organ la the occuirenoe of jtl- 
Koditnouof lo"" cells variously ecaltereJ. npon the lining membrane of l!ic 
the Uver. digestive cavity, as in the Iiydra. A concentration or local- 
ization next ensues, such yellow cclla bcuig grouped upon the wall of ik 
intestine nt a definite 8fK»t. A ca'oal projection, in the higher tribes, 
eocms next to force out the yellow cells, bearing them on its exterior, ss 
in the uudi branchiate gasteropoda; and as these coeca arc prolonged 
more and more, so, in a more definite manner, docs the nidimcntary liver 
appear. In molluscs tlus ]>artition is sullicicntly distinct. The spcdal 
form which the I>epatic ajiparatus jiresents in diiferent tribes varies very 
greatly, though doubtless the principle of construction and of action is 
Fisf. Bi always the same. Thus, in insect*, the liver con- 

sists of long tubes of delicate membrane, cOTCKod 
with secreting cells, small and gemi-likc near the 
distant end of the tube, but more jjcriect at the 
mouth. These tubes ore in relation with an adi- 
pose mass, which is probably connected with tht 
origin of the cells. The dilTcrcut condition of 
these cells, when comjiared at the bottom nad at 
the mouth of the bilosac, is well seen in tlit 
case of cnislaccans, ns in J^iff. 82, one of tlie he- 
patic cocca of the cray-tish. The letters at the 
side show the state of iho cells in diflerent posi- 
tions toward the mouth of the follicle. At a they 
contain yellow biliarj- matter only ; at i, oil glob- 
ules are appearing in them, which become more 
distinct at t* ,' and toward d and e they present 
the appearance of onlinary fat-cells. Thus, ex- 
amined at the bottom of the follicle, the cells arc 
biliary, and as we advance to the mouth they bc- 



W/ 



Btp*Mc raeonn ot eny-fiab. 

come fatty. {Leiby.) 

The comparative anatomy of the liver is repeated in its order of devel- 
PeveiopmCTit opmcnt in the high vertebrated animals. In them it is firet 
«ftboliv*.>r. detected in an evolution of cells upon the intestinal wall, at 
the point which is eventually to be the place of discharge of the common 
bile-duct. This agglomemtion of bile-cclU is next seen to project or bud 
off (hrou^'h the intrusion of n ctrcal pouch. In the amphioxus the con- 
dition thus i-cachcd remains permanent, and is the coanterpiurt of the liver 
of a fuwl about the fourth day of incul>ation. The ca'cal pouch next 
sends forth ramiBcatiotis, which ore likewise accommodated with cells, 
and these, branching again, give origin to a complicated structure In 





SrnUCTUTlE OF TEE UXEIL 

his condition, the mouth of the ctKcam becomes drawn out and narrowed 
own, and so forms the rudiment of an hepatic duct. 
In man, the liver ia the largest ghind in the body : it is of a reddish- 
own color, dense, and from three to five pounds i[i weight ; i>p»rriptioa gf 
Qvex on its upper, and concave on its inferior surface. It i'*^ ''^■<""- 
five lobes : the right lobe, the left lobe, tlie lobus rjuadralus, the lo- 
spigelii, and lobus caudatus. It is held in its position by dupli- 
jeaturcs of peritoneum and by a libroua cord termed its ligaments. Its 
ritoueol envelope is the cause of its glossy appearance ; its cellular en- 
ope extends into the interior as sheaths for the vessels. Five classes 
' vcsmU arc found within it: the branches of tlie portal vein, those of 
I bepatlc BTterVy those of the liepatic veins, the lymphatics, and the he- 
atic ducts; the latter, converging eventually into a trunk, the hepatic 
duct, joins with the cystic duct to form the ductus communis cliolcdo- 
yiy. 83. chus, which discharges its contents 

into the duodenum, as seen in 7^^, 
83, in which a is the gall-bladder, 
which constitutes a temporary recep- 
tacle for the bile, b the cystic duct, 
d the hepatic duct, c its branches, e 
the ductus cliolcdochus, and A its 
0[)ening into the duodenum. 
: Tbc ute^ocu «.kriDB th« i^^^ jjj^ gall-bhtdder is wanting iu in- 

il^-ertebratcd animals, and tirst makes its appearance in a rudimentary 
I'CODdiUon as a dilatation of the bile-duct : it is absent in tlie horse, pres- 
|«nt in the ox. ; in the camclopard it was absent in one individual, and 
ithe nest that happened to be examined hfid two. 

The intimate structure of the liver iu man is, in many particulars, still 
jamperfectly known, though the attention of the most eminent i„ijoi„tri.!nic- 
liKuitomists has been devoted to it. It may, however, be un- tun: of the Uv- 
tderstood that each hepatic vein, commencing in the substance "" 
(lof the liver, bears upon its capillaries small portions called lobules, from 
be -Jj to the Jj. of an inch in diameter, in a manner which calls to mind 
fy 81 the arrangement of leaves on a branch, or 

a bunch of grapes, as represented in I^iff, 
84, a being the vein, ^^ ^, i, leaf-like lob- 
ules on iJs branches. Excluding the lyni- 
1^ phatics, it may be said tliat four different 
systems of vessels are ciigagcd in the liver, 
the portal vein and hepatic artery, tlic bile- 
ducts and hepatic veins. The first pair 
•ue«»nmiBih«it.b«i.«ofth-.*tivor. r^^ nflcrcnt, the second pair efferent vcs- 

Thc portal vein brings the blood from which bile is to be sccre- 



200 



sTnucruQE of tub ltveq. 



^so^ 



>fc-^ 



'-~ '* 



OHcto of b^Mie roUu In Um Itvtr IoIbIw. 



ted ; the Hepatic artery brings Rcrated blood for tho noarUhinent of the 
gland ; the bile-ducta carry away the biliar}' 8Ccr«tion which has bocD 
separated from the ]Kirtal blood, and the residue, takca charge <^ by the 
hepatic veins, is eventually carried back, into the genei«l circulation 
through the vena cava. 

A general idea of tho inodo of arrangement of tlie fotir vessels in the 

liver may be obtained by recallix^ 
the iUui^tration just given, that the 
lobules are placed on tho commence^ 
nicnt of tlie hepatic veins, Iik*> grapes 
on tJicir stalks. The vein originate? 
in the centre of each lobule, as shown 
at a <7, in J^iff. 85, and exhibits thoB 
Tf^^i:^/ n ray-like kind of dii-ergcnce. On 

tlic |)criphery of each lobule, at b, b. A, 
as it were on the surface of the 
grape, tho other three vessels ram- 
ify. Of them tho ported veinlcts dip 
down into tho substance of the lol> 
ulc. The hepatic artcrioa likewise 
enter for the purpose of gi>-ing nutri* 
In J^t'ff. 86, Of a are the commencing hepatic or jntnn 
^ lobular veins of two lobnles ; b, 6, 

tlie biliary ducts ; e, tnterlobuhff 
tissue ; d rf, parenchyma of the lob- 

& ^.^fi5*?5t^Oi^:^8fesi«>32\ . ^1*^- ^^'ith respect to the bite- 

ducts, which are prominently rep- 
|_ resented in this figure, it is not pos- 
r^^ itively known whether they pro- 
ceed beyond tlio suriacc, and the 
manner in which they are related 
\l to the secreting colls, and receive 
the liquid yirJdcd by tlicm, is a sub- 
ject of controversy. The inters 
spaces between the capillaries that have entered the lobtJes arc filled up 
with these cells. 

It is not known whether the hepatic artery discbarges its blood into 

HeMtlcctllB ^''*^ IH>r1al capillaries, or into those of the hepatic vein » and, 

for this reason, it is doubtful wliether that blood takes part 

in the secretion of the bile. The secreting ceJls have nudeolated nuclei, 

and are about tlie yj^nj of an uich in diameter. 

In J^i(/, 87, at a, a, a, tlieir normal state is shown. They arc filled 
with a yellowish, granular soft substance ; &tbbla the appearance of fat 



tion to the parts. 






? 



Ottcla of Ulc-ducu on tti« Itrer lobnlaa. 



COUBSC OF THE BILE. 



»!■ 








n«p»lie «IU niBpilf ed J'.'O diunettin. 



j^bnlea, wliich increase in nanil>cr and aize at <r, c, c, c. They thus con- 
I tain both biliary material and oil globules, the quantity of the latter van,'- 
i\j. 6T, big with the nature of the food, and 

9^\ ^.r*. ^^ certain difieaaed conditions occur- 
ring to so great an extent as to ^ve 
riac to tlic aspect knonni a3 ** fatty 
liver." Thi« accumulation of fat is 
connected with the respiratory func- 
tion, not only in conditions of dis- 
ease, but even in a state of health ; 
for, tlie more energetic the rcspira- 

ttion, the more free is the liver from fat. 
Aa the chyle pnss&§ througli t]ic mesenteric glands before it is dis- 
charged into the circulation, so do the matters which have liecn taken tip 
by tlie rasciiior absorbents pass to the liver. In Chapter IV. the bile, 
which is secreted from the portal blood, is treated of as taking part in the 
function of digestion; but there is another aspect under which we have 
_ now to rc^rd it. 

B We sjtcak of tlie circulation of the blood, because, setting out from tho 
^UfBTt, it comes back thereto, pursuing a course; which retnnis nyn,-,ii,tiicgi 
^npon itself. Ill the sjimc metaphorical manner, accoixling to »i.ir«lc«>un«of 
the views of some, we might Bj>f'ttk of the spiral motion of '" ' "' 
the bile; for those of its constituents, which arc first taken from the stom- 
acli and small intestine by their veins, apjiciir to jiass in the portal circu- 
lation to the liver. In tiiiit gland a preliminary partition of the constitu- 
ents of the portal blood ensues, one stream setting off to the general dr- 
culation through the hepatic veins, and another, the bile itself, returning 
to the intestine. In the intestine another partition ensues ; the coloring 
matter of the bile is dismis^ted with the faeces, and the residue, taken up 
by the lacteals, passes through the mcflcnteric glands, and, either by tlie 
tlioracic duct or otherwise, gets into the blood circulation. It may there- 
fore be perhaps thought that the constituents of the bile have been twice, 
in close pucccsaion, in the digestive cavity, and have been twice iihsorb- 
ed, first by the veins, and then by the lacteals; and that, as it were, a 
spiral course has been pursued. 

ITlic question at once arises, what is the object of such a course ? Why 
is there this return to the digestive cavity ? The answer commonly given 
is, tiic bile takes part in promoting the operation of digestion. iJut the 
return may perlwps be, not for the purpose of inducing digestion, but for 
the purpose of beiug acted on or digested itself. The separation of its 
coloring matter, just alluded to, is a significant fact. 

The jwrtal blood, as it is preparing to enter the liver, may bo regarded 
aa systemic venous blood, the constitution of which has been altered 



SOS 



BOmCE OF TH£ BILE, 



through the additiong made to it by absorption of matters irom the stoiD- 
r tnnrtf **^^ **"** intestine. Wo may overlook for tlie present tliosc 
iiitfj'oriii hiuwi coatributiouB it receives from the veins of the spleen and oib* 
hi the hvcr. ^j, goiir^,^^^ Regarding it, tlicrclbrc, as systemic venous Uood. 
charged with certain of tlic products of digestion, it enters the liver tote 
acted njwn by thut gland. The first effect upon it is, in a chemical point 
of view, well marked. The stream which sets off to the general circuU- 
tion tlirongh the Iiepatic veins may be said to cany uwuy the whole of the 
nitrogciiized material ; for the bile, which is at this point parted out mA 
sent back to the intestine tlux>ugh t}ti! biliary' ducts> docs not contain man 
than 4 per cent, of nitrogen, and this excluMve of the water which im- 
Connte and P*'^ '° ** ^^^ liquid condition. jVrri\'cd in the intestine, a rep- 
•apttniUcmof ctition of the same process of {lartition takes place, tlie color> 

" ' "' iiig matter, whicli contains nearly the whole of this residual ni- 
trogen, bt'ing di&niisscd witli the fa'ccs, and tlu5 remaining hydrodxboD 
taken up by the lacteals along with otlier fats. 

The first duty of the liver is therefore a separation of tlic nitrogcniwd 
principles of tlio portal blood, which are forthwith carried into the geo- 
cral cinndation tlirough the hepatic veins and the vena cava. The result 
is, that there is returned to the intestine a sulphurcletl hydrocarbon, still 
containing so much nitrogen as to form a very nnstablc product, prono 
even to spontaneous decomposition. 1 n the intestine its nitrogen is whol- 
ly removed from it, and tlie combustible hydrocarbon is then absorbed. 

The portal blood, regarded under the aspect here presented, is obvi- 
FVom lut O'^^^y composed of two constituents: 1st. Systemic vcnota 
aoarccUtliA blood ; 2d. ilattcrs obtained from the digestive cavity. Wc 
bOedsrirodr ^^^^ inquire from whicli of these the bile is really derived. 

Besides the presumptive evidence arising from the consideration that 
if the bile originated from matters which had been just absorbed from 
the digestive cavity, it would l)e inconceivable why it should lie rctamcd 
forthwith thereto, its quality of extreme instability marks it out ns a sub- 
stance fust approaching to final disorganization and dccomi>osition. It 
bears no aspect of a histogenctic or formative body, but, on the contmy, 
it is on the downward course. We shoidd scarcely expect to rccognue 
it as a primary product of tlie digestive action, but should seek its prob- 
able origin in some source of decay. 

Whatever weight may attach to such considerations, we tiave, in addi- 
tion, direct evidence which places tlie source of the bile beyond doubt by 
rRferring it to tlic systemic venous blood, and not to the matters just ob- 
tained from the digestive* cavity. 

During fa?tal liti% the digestive organs are in an inactive state, but the 
liver, which is largely developed, discharges its secretion into the intes- 
tine. This secretion, which is known as the meconium, is a true bile, as 
the following analysis proves. 



BILB 13 DERIVED FHOM VENOUS BLOOD. 



203 



CofMfiotilion o/" Mfcottiam. (From Summ.) 

Cholerterinc 160.00 

ICxtrocUru ui<l Ulifclliiiic acid UO.OO 

Casein 340.00 

Bilifellinic udd stid btUa „ CO.OO 

Bilivcrdio nnd tiUrollinic iu:id 40.00 

Celb, muciw, idbumcD 2GO.O0 

1U0O.UO 

Dr. Davy found lliat the ash left after the ineincralion of a eaiiiple of 
mecoiuam is of a reddbh color, consisting chiefly of peroxide of iron and 
DiagTiGsia, with a trace of phosphate of lime and chloride of sodiuni. 

During ficlal life the liver is therefore discharging the same function 
that it doca after aerial respiration has commenced, tEiat is u <)«>« not 
to say, it secretes bile (meconium) into the intestine; hut at ^°"*!' 'i"'" '^, 
tins period, Hincc there is no true digestion, the bile can pmJucu. 
come from one source alone, and that source is the Bystcniic venous 
blood. There therefore can remain no doubt tliat, in after life, the samo 
effect takes place, and that the bile is never derived from materials which 
Juve just been brought from the digestive cavities. 

^ I therefore regard tlic bile aa an iixcrction of matcriaiR whicli arc do- 
compoKinjj and ready to be removed from the system. I in- , 

* o f ^ ... " comes irora 

cline to the supposition that much of it is deiivcd from the itirrtnonj 
cells of tlie blood, the lit't; of which is only temporary, for the 
BBsein of the meconium is nothing but the globulin of tlie cells, the two 
Fubstanccs being chcmiwdly allied, nnd the predominance of iron in the 
ash of meconium seems to establish a connection with ha^matin. ilorc- 

er, this opinion is supported by the remarkablo stabiUty of many of 
ic nitrogcnized coloring matters, the analogies between ha-matin and 

lorophyl, and particularly liy tlie fact ihal in the herbivora the coloring 
atter of the bile is undislinguishablc from clUorophyl, and in most oth- 

trihes closely allied tliereto. 

In any discussion of the action of the liver, it is thus to be constantly 
borne in mind that the portal blood consists of two distinct portions, sys- 
temic venous blood and matters absorbed from the digestive apparatus. 
Iterived from the first of tliese portions, we trace the origin of the bile to 
the waste of the tissues, or to the blood-cells on their downward career; 
Itnd hence we arrive at the important conclusion tlmt every proximate 
Kmstitucnt of the bile pre-c.xists in the systemic venous blood. 

Lehmann, inchning to the view that the formation of the bile oecura 
in the liver itself, quotes the experiments of Sliillcr and Atitnj[>t*todc- 
Kunc, who, after tvinj; the portal vein and applying liea- ''''^"' '-■'"'''•' '"■■'^* 

II • ." ^ , ^ » 1- ■ ,' aniMiile pig. 

tozes to all the points of attaclimcnt oi the hvcr in irogs, ex- mvat in Uie 
tirpated Diat organ, and collected the blood of those which ^'"^ 
Burvivcd the operation for two or three days, by amputating their (highs. 



204 



coN-STrrtmoN op bile. 



It was expected ihat in this blood, bile pigment and cliolic aciJ wooU 
be found if the original formation of those Bubstaocca took place txxa- 
nalljr to the liver. Such did not prove to be the case. It may, hoircrrr, 
be justly inferred that no reliable conclusion can be drawn after opoft- 
tiona of such magnitude and severity. 

The alleged inability to detect the constituents of the bile in tbeUood 
Cause of iliU of thc portal vcIn is probably due to tlie defects of ourtni- 
ftSn's'iao Jr h'^^^^^ processes, for it is very clear from the circnmstjuwe 
the Lioo.1. tliat thc bile which is poured into the intestine must be reab- 
sorbed, with the exception of its coloring material, either hv the laemb 
or the veins, or by both, since it is not found in the excrement. Tlirougli 
whichever of these channels it passes, it must therefore regain llic gen- 
crnl circulation, for it can not be supposed that in thc short period of its 
course it could have undergone complete metamorphosis. 

We may therefore assume that the proximate ingredients of bile pre- 
exist in the blood, and this conclusion is enforced by the fact that, after 
tying the vena porta, bile, though in a diminished quantity, is still 9^ 
crctetL Thc same also occurs in those cases of malformation in whicb 
that vessel, instead of ramifying into the liver, em2>lie-s directly into the 
vena cava. When there is any failure or delay in the removal of bile 
from the system, t!ic eftccts are such as might even be predicted, nervouB 
disturltancc ensuing, and eventually all the 9^^nptoms of poisoning. The 
circumstance that this last eficct often takes place 8u«Menly, has been Iff 
sonic supposed to be dcjiendcnt on thc necessity for llic bile to accninn- 
late, to a certain extent, but it is much more likely that it is dctennined 
by thc metamorphosis of the decomjwsing bile having reached a ccrtab 
jxjint, when s|>ccial poisonous products have spontaneously arisen from it. 

Bile, from whatever animal it may have been dcrivM. contains a resin* 
Consiitution of ous soda salt, a coloring material, chole.-itcrlne, and mncns. 
**''*■ The acid of the soda salt is the tanrocholic or glycocho- 

lic. Tlio coloring matter in carnivorous and omnivorous animals is 
brown, tlie chnlepyrrlnn of Berzelius ; but in birds, fishes, and amphitua, 
it is green, Lilivenlin. Strecker makes the curious remark respecting the 
bile of fishes, that in those which are of salt water, potash salts predoni* 
inate ; and in those of fresh watpr. soda salts. Among the ultimate ele- 
ments occurring in thc bile, and lieing of special interest, may 1w men- 
ConAiitutiuaof tioned sulphur, which exists in tanrine, of which the com- 
tanrun:. position is C^, IL, N, S^, O^. It may be obtained from ox- 

gall ; it has likewise been made artificially by Strecker from thc iscthi- 
onate of ammonia. It is distinguished by evolWug sulphurous add 
when burnt in thc ojwn air. It docs not exist in thc bile in an insa- 
latcd condition, but probably as an adjunct to cholic acid, and lias been 
found in tliat secretion of both hot and cold-blooded animals. It lias, 



"*»» J 



QUANnTT OF BIUL 



205 



» 



lowever, been asserted that sulp]iur» and Ibercforc faurocholic acid, does 
sot exist in tliu bile of tlic hog. 

The bile 13 secreted more slowly during a long pcrioU of fasting, and 
jDore rapidly during normal nutrition. To a certain extent, ProdueUon of 
thia Tariable rate depends on llic general principle that a ''''*■ 
gland acts more energetically in proportion as the supply of blood sent 
to it is greater. If not wanted for the present purpose, tiic product is 
storuj up, for a time, in the gall-blnddcr. 

WUtn the bile has bccu long retained ui the gall-bladder, it becomes 
concentrated through the removal of a portion of its water: chnnt^oTbilo 
it also undergoes a change of color. In animals whose ho- «**« ivtemioa. 
patie bile is yellow or brown, the cystic bile has a tendency to green, a 
dwDge of color dependent on partial oxidation, occasioned by the arte- 
rial blooil. 

The tlow of bile takes plaeo with diticrent degrees of r.ipidity at dif- 
ferent dinmal periods : thus it reaches its maximum in from ^^^^ otmmx- 
thirteen to lifteon hours after the last lull meal, and then iinum How or 
npiiUy diuuui.-:hcs. 

Bidder and Schmidt estimate the diurnal secretion in an adult at 54 
Oz.t containing o per cent, of solid matter, an estimate which is undoubt- 
edly too liigh, so far as an average diet and state of health are implied. 
It is asserted lliat a diet of fleah tends to produce more bile than one of 
m purely amylaceous kind. Even the u°te of a large quantity of water 
incTMses its amount, and this as regards its solid constituents. Kemc- 
dial agents act in various ways. Calomel increases the fluid, but di- 
miniabes the solid constituents. Carbonate of soda diminishes botlu 
Again, there arc great variations in the rale of its production: the circum- 
stance just mentioned, tliut its maximum How is several hours after the 
maximum digestion, is important as regards the explanation of its forma- 
tion, showing signilicantly that it is not directly produced from matters 
recently absorlx^d from the intestine, but from the systemic venous blood. 

Bat the liver lias other duties to discharge besides the separation of 
bile. It gives origin to sugar and fat, as is proved by tJie Other dutie* of 
cinrtuustance that the blood of the hepatic veins is richer in ^i^j'^'p^my 
those ingredients tlian tlie blood of the jxtrtal. In this re- ing l»>i«- 
Bpect its action seems moni particularly to be that it converts other sug^ 
ais into the particular form knowni as liver-sugar, which it can also pro- 
dace £rom the tmnsfomiing albuminous bodies ; it forms fat from sugar, 
and makes from certain other fats the six-cial one known as livcr-fat. In 
thii* duty of forming sugar and fat, it exhibits an inverse power of action ; 
as the production of the one predominates, that of the other declines. 
K Fri>m the point of view which we liave now reached through this do- 
B acription, we are able to see the double duty which tills great gland dis^ 



206 BILE REMOVED FROM BLOOD BY FILTRATION. 

The lirer doM chflTgcS} and mnst correct, to a certain extent, the popular 
not torm \)H^ theory of its action. Docs the liver really secreto bile T Is 
it the business of the so-called bil^socretin^ cells to withdraw the coii5(it- 
uents of llmt liquid from the bIot>d, aud combine tbem t(>gcther into this 
viscid yellovr liquid? I tlunk not; for it is a matter of demonstration thit 
not only every constituent of the bile, but the bile itself, pre-exists in the 
blood, and it is just as un philosophical to burden those cells with the 
duty of forming it aa it would be to believe that a like agency is needfiil 
for the np|>canu»ce of urea in the kidnev. lilorcovcr, we must constantly 
bear in mind the extreme instability of this substance, how readily the 
yellow bilo of camivorouB animals becomes green by partial oxidatioUf 
nnd the green bile of the herhivora yellow by deoxiJation, It spontane- 
ously changes in its downward career, and any ditl'enmccs in quality or 
character wtiich we might impute to the action of tlic cells upon it miy 
1)0 c(|ually well attributed to its own inherent principle of choDge. 

For these reasons, I bchevo that the bile simply transudes from the 
Vannpr of blood, and that tlie cells uf the lobules liare no special relatioa 
leoioviiigiu ^Q j^ beyond this, thot it oozes past their interstices, or, pcrhi^ 
by physical imbibition, finds access to their interior. I sco no reoMO 
that these cells sliould form it when it pren^xists in the blood, nor does 
tlie state of the afiluent and effluent blood ofler any contradiction to this 
conc-luaion. In all discussions of the functions of tliis organ foundol 
U[x>n a comparison of the jwrtal and he|>atic venous blood, the rclatiTc 
f|uanttty of water which they contain, and its great and even rapid flue* 
tuations, shoidd always be borne in mtud. .Vs might be expected, portal 
blood contains far more water, and, even after abundant drinking, the 
amoimt in the hepatic venous blood has by no means inciefiscd to the 
extent thot might have T>een expected. It is for these reasons that the 
bile varies so greatly at ditl'erent periods in its specific gravity and 
Buidity. 

The blood of the portal vein is, moreovej, periodically \*ark'ing in its 
Varifliion In constitution, according to the state of activity of tlie organs 
Ii'o''n~?SoMr. ^'^™ 'whlcli it is being derived. In the first stages ofdigcs- 
ml Uitoii. tiou the stomach is supplying it in unusual quantities, and 
with the ingredients whidi its veins liave been absorbing from the result 
of histogcnctic digestion. A little later, the same thing occurs with the 
intestine. At anotlicr period the supply from the spleen varies. 

The explanation which Mr. Handlicld Jones hss recently given of the 
Funciionnrtba functiou of the hejiatic cells — that they manuiuctnre liver- 
iic]>aUi: otiia. sQgar — deser\'C3 attentive consideration, more porticulariy if 
we likewise impute to them the production of liver-fat ; for this would at- 
tach them rather to the ramifications of the hepatic veins as a ]}art of their 
instrumental mechanism, and assign thorn only a voiy mdirect relation to 



PRODCCnON OP PAT AND fiUCAiU 



207 



bUc-dncts. The contradictory etatementg which havo iKK-n made l>y 
most emuiCDt anatomists rcsijccting the councctiou of the bilo-ducta 
mud the Kle-ccUa — sooic believing that the bUe-ducta are covered iiite* 
jiorly nnth the cells ; othera, that the. ducta end on the outside of the 
lobules ; others, tliat the passages reported to liavc been seen among the 
cells are interstitial channels and not proper vessels — make it just aa 
probable, anatomically, that the cells belong to the hepatic veins as (hat 
they belong to tlic biliar)' ducts. 

It is true tlmt there may be n mixed action, and that presence of bil- 
iary matter may be necessary to tlie sugar and fat producing agency. 
This intenvorking and mutual dependency of fimctions is not without a 
jandlel. Thus the lung, viewed as a secreting or excreting gland, lias 
tor its object the removal of carbonic acid from the system ; but it also 
discharges another duty, which is dependent for its accomplishment 
Qpon the physical or chcmicid qualities of tlic ha?matiii of venous blood, 
the introduction of oxygen by aerating or arteriidizing. But the excre- 
tion of carbonic acid and the introduction of oxygen, though separate 
pfaysioiogical cvojits, and to be sfwkcn of as distinct functions of the 
long, arc yet nevertheless interconnected ; the one is essential for the ac- 
complishment of the other, and the one elfect is made the means by 
which the other is brought about 

So it may be in the liver: the contact of bile \7iih the secreting cells 
may be essential to their sugar or fat producing action. 

Tlie deposit of fut and the production of bile seem to bo inversely as 
each othoT. Bidder and Schmidt found that fat animals KctaUonortbe 
yield Icsa bile than lean ones, and that when they were fed oIJrpio^L'tU.a 
on iat the quantity was smaller than in tlie case of animals ufuiv. 
fed on a less fatty diet. From such facts, the inference has been drawa 
thml the accumulation of fat is in consequence of a diminution of the se- 
cxetion of bile, and not that the diminution is the consequence of the an- 
imal l»eing fat. In such discussions it should, however, \k recollected, 
that tlie fats do not furnish all the substnnces required for the produc- 
tion of bile, but only a limited portion thereof. Thus there are reasons 
for the belief that sugar, lactic acid, or some other allied body is essen- 
tial to that process, and it i."* vf.ry dejir that so too arc the mAtcriala 
famished from the decay of the cells of the blood. 

AV'iih respect to the production of sugar in the liver, it may bo re- 
maned, that the quantity of that substance in the solid ros- p^Ho^j^^ ^f 
idae of the serum of hepatic blood is from ten to sixteen *iiff»r and flit 
times greater tlian in the same residue from the port-ol blood ; " ' "*'■ 
and in animals undei^oing starvation, though no sugar could be found in 
portal blood, it occurred to such an extent in the corresponding he|tatio 
ve&ous blood, that Lehmaim found that its quantity could be determined 



208 



IXFLUEKCE OF FNEimOGAfiTBIC KEBrE. 



hy fcnnentation. from this there can be no doubt that, in the diAngcs 
which arc occurruig during the ptutsage of the blood tlirough tJic hvcr, 
there is a [jroduction of sugar, and this seems to be connected with a dim- 
inution in the quantity of fat ; for if an excess of iat and a deficicnnr 
of sugar enter that organ, and their (luantities are inversely changwl ai 
their emergence from it, it would appear that fat may be decomposed act- 
ually, as wc know is possible hyputhetically, into choUc acid and sugai; 

But with respect to taurine, tlic adjunct of the cholic acid, since it is a 
Tanrino cohm nifrogcnized body, we are obliged to seek for it in some olh- 
frcrni Mood- cr soDJcc, and this, it would appear from tlic facts set {arth^ 
most be the regressive inctamorj>ho8is of the blood-celk 
Taurine Ims not as yet been detected in the portal blood. It can not lie 
supjxjscd that the sulphuric acid of the portal blood is used by deoatidi- 
tion in the preparation of free sulphnr for the taurine, since, if any thing, 
the quantity of that acid in the hepatic venous blood is increased. From 
whatever source it may have been derived, the sulphnr of taurine entered 
the liver in nn unoxidlzed state. 

When we reflect that the bilo is the product of decay, that it pr^^- 
ists in the blood, that on its arrival in the intestine a part of it is cut 
out with the fa-cal matter, it seems very ujilikel}' that an immense cell 
apparatus, constitutiug the largest gland in the whole system, should te 
Aii»logi«ln necessary for its removal. But when we moreover rcflwt 
SuSnBMsmr^ that ui thc uicchanism of plants, from gum, or rather (xm 
ud fitL carbonic acid and water, under the agency of cells in ibe 

leaves or other structures, both sugar and oik are formed, we recognitt 
that there is a connection between those organisms and these products. 

M, Bernard's experiments seem to show tliat tlic flugar-forming fitoc- 
inflnenec of tion of thc Uvcr may be morbidly increased by wounding tk 
th« pneutno- tnedulla oblongata near thc ongin of the pneumogastric nerve, 
on thi! quanii- or by tfic application of galvanism to the same part, an arti- 
t>©f»iigor. t'lc'ml diabetes ensuing, and this within a few minutes after 
the operation, but it usually ceases after two or throe days. It is accom- 
panied by a great derangement of respiration, a lowering of the tempera- 
ture, and a venous condition of thc arterial blood. It by no me-ans fol- 
lows, however, that tlic excess of sugar obsen'ed in Benmrd's experi- 
ments arises from an increased action of thc liver, or an increased energy 
of the sympathetic nerve : it may be, as Kcynoso asserts, attributable to 
llie injury inflicted on the pneumogastric, and diminished rcspiratioa 
Tiio administration of etlicr and chloroform, 'the conditions of old age and 
foetal life, the influence of many diseases, as chronic bronchitis, asthzna, 
pleurisy, all present a tendency to the accumulation of sugar in thc urine, 
tlio sources in each of these cases being attributable to i-cspiratory dis- 
turbance ; for if any thing occurs to retard or delay the destruction hy 



^ 



DESTRrCnOS OF BLOOD-CELtS IS THE MTKTI, 209 

oxidation of llic sugar, constantly lormeJ by the Uvor, the accumulation 
will make its npiwnmnce in the urine. The ap|)caraucc of flaccharinc 
matter in that secretion may l>c ecjiialiy well attributed to its non-tlc- 
stnietion in the system generally as to its ovcr-produetion by tlic liver. 

This gland, l>C5ides producing sugar and fat, is llic scat in which the 
worn-out blood-cclla are finally disintegrated, and probably n . ,- * 
the Toong ones pushed forward tlirougli a certain stage of )ilwM^ct-iu ia 
their dcvehipmont ; ailvantagc, moreover, being incidentally * ""' 
taken of the secreted bile, which |w>sscssea projiertlcs u-wful thongli not 
ttsential for promoting the digestion and absorption of fatty material, 
perha|)s, also, of ini]}arting a dclinitc course to the transmutation of the 
icmi-digcste<l material in the intestine, and this both as regards nitro- 
genized, amylaceous, and fatty bodies. Of tlio influence of the bile in 
promoting the absorjition of fat, llm ])hy8iial cxperinifnts which have 
been alluded to leave no doubt; but that llieso nses arc of a secondary 
or Don-esscntial kind, and arc only taken advantage of in an indirectly eco- 
nomical way, is established Ijeyond all possibility of a doubt by the fnct 
that animals can Uvc for a long time, even for months, witliout the pas* 
»ge of bile into the intestine, provision having been made for its escape 
externally through an artificial iistulaus orifice. 

These conclusions respecting the functions of tlie liver are in harmony 
with the appearances presented by the blood leaving and entering it: 
the predominance of colorless blood-cells, and of young cells well ad- 
Tmnocd towanl |)erfection in the former, and of wasted, worn-out ones in 
the hitter; with the fact that tlic maximum secretion of bile docs not 
lake place until more than hnlf a day after the ingestion of food ; and 
that during fictal Htc, in which tlierc is no food, cither in the stomach or 
intestine, to be digested, the liver is nevertheless in high activitTr-, and 
Lite is secreted. 

In view of all the preceding facts, we may therefore finally conclude 
llut there are at least four distinct operations conducted in the Uvcr; 1. 
The {iroduction of sugar and fat ; 2. The separation of the bile ; 3. The 
dcstmction of old blood-cells ; 4. The completion or perfection of young 
blood-cells, jxirhaps by receiving their iron, "With respect to tlicse it 
maj' be remarked. 

First. The formation of sugar and fat, cither from carbohydrates, or 
vhat, in this instance, is more probable, from albumenoid bod- CpnenU nam- 
ic8 bronght by the portal vein, can no longer be doubted. J^*i/rft2*'iiJl 
The prevalence of liver-sugar and livcr-tat in all that region er. 
of the Tenons circulation included between the liver and the lungs must 
be attributed to this source That the sugar undergoes rapid metamor- 
Itosis in the pulmonary organs is plainly proved by the effects of inri- 
tation of the pncumogastrics, whidi. interfering with the f\inction of rcs- 

O 



L plic 
^^ati 



210 



SrUUABT OF TUE ACTION OF THE LHXB. 



piralion, pormit this eubatAnce to reach the aortic circul&tlon^ from which 
it is removed by the kiiincjs, a diabetes aiising. So lar as the prepftn- 
tion and course of this sugar is concerned, the liver is a ductless glto^ 
and, with Sir, H&ndticl J Jones, I believe that the cells of the liver are the 
agents wliich accomplish this duty. The production of fat appears to be 
inversely as that of sugar. In the crustacean bile-sac* J^ig. 82, we see 
the gradual stages of it^ appearance; and the production of both bodies 
is well illustrated in the life of plants. 

Second. The bile is separated from the blood portion of the portal 
blood, and not iroin the products of digestiou obtained fiom (he ctiylO' 
poictic viscera. The elements of bile 1 believe to pre-exist in the blood, 
and to escape from the portal veinlets to the biliary ducts by mere filtra- 
tion or strainagc. The precise source from which the bile is derirai 
is probably the blood-cells, and In the cliangea wliich they are undo- 
going iho spleen is [jcrlmps conceiiicd. If this be so, the bile-^uctit 
as much a duct for the spleen as it is for the liver itseK The bile nur 
almost be looked ujwn as a hydrocarbon, containing a very chaogcahle 
and therefore noxious coloring material, whiclt, when the secretion readh 
es the intestine, is parted from it and dismissed with the fccces, tJie pn^ 
er hydrocarbon being taken up by the absorbing arrangement for bydio- 
carbons, the lacteals, and so sent through the thoracic duct, Pethipe, 
also, by reason of its special adaptedness for that purpose, it aids in tbe 
absorption of other futs. 

At this point it may bo remarked that the view hero presented of the 
sugar-forming and bilo-s training functions of llie liver appears to be 
greatly strengthened by the anatomical conslruction of tliat organ. 
There is no ob^-ious communication between the portal and bcjmtic vein- 
lets save through cells, but the portal veins and tho bUo-dncls run if. 
their ramifications side by side. 

Third. Whatever part of the disintegration of old blood-^sella takes 
place in the spleen, their final destruction is doubtless accomplished in 
the liver, this being the immediate source from which the bile itself ifi 
derived. Though these metamorphoses are, to a greater or less extent, 
occurring throughout the circulation, it is in these two great glands thai 
an opi>ortunity is afforded for the destruction to reach its completion, and 
the resulting product of waste to be removed ; nor is there any thing in 
this view at all contradictory to titc opinion I have enforced, that all the 
constituents of the bile may lie fninid in the genend cirenlatinn. 

Fourth. Tlie liver also aids in the preparation or maltiration of young 
blood-cells in an indirect way. There are certain of the mineral constit- 
uents of the disintegrated cells too valuable to be cast away, since (hey 
can subserve the duty of entering into tho composition of young cella 
passing to\^*ard perfection. As such a substance may be mentioned iron. 



' 



THE DUCTLESS OLAXDS. 



211 



liis view of the action of the liver appears fiUo to l;e sustained by the 
up* number of star-liko. and comigatcd blood-cells occurring in the 
ortaJ blood of fasting animals, and which are replaced by such as appear 
> bo jronng and perfect in the blood of the hepatic veins. It is not, 
owever, to be supposed tlint ail the iron is economized in this manner : 
considerable portion of it accompanies the pigment as an essential in- 
^ient, and ia finally discharged through the intestine. 

OP TlIK DUCTLE!-;s GL.\XDS. 
The salivary and sudoriparous glands discharge their secretion directly 
irough ducts. The liver and kidneys have upon their ducts tii.- <ii.etie«i 
n additional mechanism, the gall bladder in the one case, and gi*""ij'- 
kc nrinary in the other, which serve as receptacles for storing up the 
iroddct of action in a temporary manner, and so converting the continu- 
kLscficct of the gland into a periodical result. In each of these instances 
re may arrive at conclusions of a certain degree of exactness respecting 
»e functions and use of the gland from a study of the secretion it yields ; 
bt there are in the system other glandular organs which differ essen- 
ttUy from all the preceding in not being furnished Avith ducts. These 
re the spleen, the thymus and thvroid glands, and the supra-renal cap- 

Much diversity of opinion prevails respecting the true nature and ac- 
ton of these bodies. From their structure bearing a resem- Ti,ar Buppowd 
lUnce to tliat of the preceding, with the exception of the ab- fun»;Uon». 
Bnce of a duct, many have thought that, like them, ihoy are really sccret- 
lig organs. Others have supposed that they have a relation to the nu- 
Htion of the system, in giving origin to the development of cells, or that 
ley HTC connected with the organization of tlic blood itself; and that 
Bch is their duty is jwrhapa rendered probable by the circumstance that 
wne of them, as the thymus and thjroid, exhibit their utmost develop- 
lent when the body is rapidly growing, and diminish when maturity is 
Acfaed, That they enjoy a community of action, or that their function 
ricariouply discharged by other organs, has been clearly cstab- 
by the result of opci-ations in which one or other of them has been 

tirpated. 

With respect to the q>lccn, the views of Professor KoUikcr are sup- 
lortcd by many facts. He snpiwscs that one of the chief tunc- Function of 
ions of that gland is the dissolution of the disorganizing blood- **** ■?!««»• 
bUs preparatory to the action of the liver, in which ha*matin is to be 
MTerlcd into the coloring matter of the bile. In the discussion entered 
Mo respecting the origin of the bile, we have come to the conclusion 
mt it is derived from the systemic venous blood, and in the supposition 
piesented respecting the function of the spleen there is nothing con- 



313 



TITE SPLWK. 



tradictory, for it is to be remembered that the blood of the spleen ia 
constittient of the portal circulation. It also appears to be a gencnl 
opinion that the Bplecn likewise maintains ft mechanical relation to tkt 
portal mechanism by een-ing as a receptacle for any excess of bW, 
and thus relieving the ve^^sels of pressure, or by acting in like maiiw-i 
when there is any obstruction to the passage of blood through the livci. 

As our knowledge of tlic action of the ordinary glands becomes won 
AndogTorihc accurate, the function of the ductless glands loses much of 
JiSh'iSlTdlwt- ^*^ peculiarity. As we have already stated, in a certaia 
less. sense the liver itself may be said 1o be a ductless gland, (or 

it appears to bo one of the constant duties of that organ to prqiare sog^ 
from materials in which it did not prc-^xist. And thin sugar does not 
escape through the hepatic ducts in company with the bile, but is taken 
directly into the system Ihrougli the hepatic veins. But this principle 
of action is identically wliat occurs in the case of every ductless glaai 
and hence it may be inferred that the changes which these impress ontho 
blootl arc necessary for the development and nutrition of the system. If 
the doctrine of KoUiker be correct, the spleen is only an apiKindbc to tk 
liver, and the same duct answers as a common outlet for both. 

The views here alluded to are enforced by the examinations which 
KBtnw of Iiavc been made of the blood of the splenic vein. The fol- 
»pi«iac lOood. lowing table exhibits the contrast between it, that of the e:i- 
tcrnal jugular, and that of the mammary artery. 

CoiutU*a!oH ofS/ifetic lilood. (From Srffrer.) 





Mkinnury .^rt»rr. 


F.tL .I.|>ri>t>tr. »ftaaey^tK \ 




7M).60 
159.90 


TTtl.W 

7y.40 

141.70 


746.80 

134.40 

1SB.90 

.40 




Corpoades and Fibrin.... 
Lo»a. 




1000.00 


1000.00 


1000.00 



From which it appears that the blood, after circulating throagli the 
spleen, has lost a large portion of its cells, the relative quantity of its 
albumen is greatly increasetl, and, moreover, from being llie basic albu- 
minate of soda, the foitn under which it ordinarily occurs in the blood, 
it has become the neutral albuminate, as in proved by a turbid aiipear- 
ancc on the addition of water, and this state it seems to retain daring 
the portal circulation, for the blood of the hepatic veins exhibits tlie same 
peculiarity. 



OP ESCOETIOX. 



213 



cn.\j>TEii XII. 

OF KXCIiETlOX. 

THE raiXt:, HILK, XSU CCTAXEOCS EXCSEnOSI. 

Stentiom mid Eitraiou. 

Qftim ISdn^: its StmctKn and Funeiioan. — J%f Ma/pifjlii/in Oroiffititm. — T^c Vriite: U* In- 

frwAntta, t^tir X'isriatvm* ami S<mrcrM. — AhnortmU Stdnitaitce* in it.— Tfi* WtUer faid Anlla 

cxadk hj fShration. — 7%^ CV/2* remove nhoiidised Sodia, — .l/dirner nf Remorvii of the Litptid 

/mm (At ArafpwfMian Sac 
QT lAe Mammary CSbmd: %»• Strneturt.^Chlottnan atul ATiU-.—InfftwHrutM q/" Jt/tflr ourf thrir 

FWiafamu.— /i»/htfiKis oflMet. — ftiffuirginlo thf Origin of the jHt/rftUatUi r>/ the. Miff:, iUKat^ 

Ouni, iSii/u, Smyar, — Manner q/" Anion of'tlx (i&inJ by Straiita;/t, 
Q^ dU Stin. — Smtrturf nf its Epidermo ttntl Derma. — SwforipamvM anj ,Sff>ar»^tut Olmttin. — 

ftaiia.—Umr.—Jn^tdient* of I'^ritinratim.-^Kxhaiation: ilM Anujftt.—C^nmtii of 1^ I'ari- 

^Ut Anitm cf iht Skin. — lit DouliJe Action. — Af>»orfttio» hjf lAe Stim. — Grneral Simanonf of 

fiW OlbUMMU /Mfirf ioflJ. 

The function of secretion is very commonly treated of by physiolo- 
gists under two divisiona, secretion and excretion. The £>i,,iop^o„ j,^ 
former refers to the separation from the blood of those fluids iwcemecrBiioii 
which are rwinired for the uses of the body, and wliich are ""' 

thfrrcforc still retained ; the latter, to those which ore effete, and to bo 
cast out aa cxcrcmcntitioos matter. Of secretions, the saliva or the pnn- 
creatic juice m&y be taken as examples; of excretions, the urine. 

But this subdivirtion is only one of convenience, and has no natural 
foundation. The so-called secretions arc, in many instances, far from 
being more highly elaborated bodies; lu reality, they arc often on their 
descending career. And among excretions, if milk be enumerated, as it 
oogrht to be, since it is a dismissed product of the system prcimring it, 
we have, instead of an cxcrcnicntitious, a pre-eminently nutritive body. 

Nevertheless, since this manner of considering the subject offers con- 
siderable conveniences, I have resorted to it for the preceding and pres- 
ent chapters. In thw I shall accordingly treat of the urine, the milk, 
and tlie products removed by the skin. 

■ OF THE KIDNEYS. 

I Tl»e products of waste arising from oxidation in the functional acti%-ity 
^uf the system, and wliicli are of a non-gaseous kind, the use- p^ ^j^, ^^^ 
^mmtB materials, saline or othcm'ise, which have been absorb- lion uruiekid. 

■ ed in the digestive tract, and carried into the circulation, *"'^" 

must be removed. Gaseous substances and vapors may pass away 
through the lungs, but soUd material must be excreted in a state ot so- 



214 



STEfCTURE OP THE KIDNET, 



lution in water. To accouipUsli this object, a spedal mechanism, lite 
kidney, is introduced. 

From this nianner of considering the fanctional duty of the kidney, it 
Is very clear that a epe<ual relation mast exist between tiii^ excreting vr- 
gan and the respiratory mechanism, for iu tho case of ammaU vhicli 
breathe by giUa, or in, those which, thougli subscqaently atroosj^iinc 
breathers, receive their supply of aerated blood before birth by n jUaucntx 
the couditions under wliicli aeration takes place are Buch as i>ermil llic 
removal of solid material by the respiratory mccUanism. The oriitH^' 
excreting ap[mratua of an animal breathing air \s therefore ncccssaclr 
buidencd with an cxclosive duty, which ia shared by the gills and tia 
skin in a water-breather. 

In iishea, the renal apparatus i^ constmctcd under ihe condition here 
_, ^^. J indicated, and though in many it appears to be greatly de- 

Lirdi. fi»k», vejopcd, extending aa a tubular arrangement from the akoll 
** "'*^ through the abdominal cavity, it is to be regarded as analo- 
gous to the Wollfian bodies rather tlian to the true kidney. In reptilea 
the proper kidneys apjwar; in birds tliey arc well developed, but their 
secretion is, for the most part, a semi-solid substance, chicHy urate of 
ammonia. The tubular form is presented in both insects and araehm- 
dans, discharging its secretion into a cloaca. 

Iu man the kidneys may be described as a pair of dark-red oroidbod- 
Tlin kiauc^ in 1*^3, placed one on each side of the vertebral column, in the 
■"">• lumbar region, the right kidney being a little lower than the 

left. In the adult tho kidney is four or five inches in length, and is en- 
veloped in a mass of fat. IJlood is brought from the aorta to supply the 
organ by the renal or cmulgcnt artery, and is carried back by the craul- 
gent vein into the inferior vena cava. During its passage through the 
kidney tliere is removed from the blood a liquid secretion, the urine, 
which, Howing down a long channel, the ureter, is emptied into the blad- 
der, from which it may be periodically removed. 

The supra-roiial capsules are bodies of a yellow-red color placed above 
Sopra-nn&l the kidneys. They are madi larger in the fcetus than in the 
capsnlM. adult, and doubtless have a reference to the peculiar conditions 
of respiration obtaining at that time, for, as wo liavo just observed, the 
renal and respiratory uicchanisros are necessarily interconnected. 

The substance of the kidney is described as consisting of two per- 
Minute rtrac ^*°"®» *^*® cortical and the medullary or tabular, as seen in 
turo aniioktd- J^j'ff. 88, in which 1 is the supra-renal capsule ; 2, the vascu- 
°'^' lar portion of tlie kidney; 3, 3, tubular portion grouped into 

cones ; 4, 4, papilUe projecting into ealiccs ; 6, 5, 5, tho three infiindi- 
bula; G, the pelvis; 7, the ureter. (Wilson.) From which it appear* 
that the cortical substance is the external portion, and tho tubular is 



d 



THE BtiLPlOUIAS CORPrSCLES. 



216 



8MUoB«ftb« fcldnw}-. 



' *^ grouped into cones, the base of each cone teing 

oatward, and the point toward the pelvis of the 
kidney. The cortical substance, however, envel- 
ops the coneii nearly to their points. It ia of a 
red color, and is the seat of the secreting action. 
The urine, as it arises, passes along the fine con- 
vergent vessels, the uriniferous tubes, and these, 
coalescing as they approach the points of tlie cones, 
give origin to what are termed the ducts of Bellini, 
From these the secretion posses into the calicos, 
tlience into the pelvis, and so along tho xirctcr into 
tlic bladder. In tlic cortical substance there arc 
large numbers of dark points, the llalpighian bod- 
ies. Their diameter is about jj^ of an inch, 
r. Bowman has demonstrated that the minute structure of the cortical 
portion is as follows : The urinifcrous tubes, as they approach it, under- 
go bifurcation in such a way tliat the branches continually arising have, 
for tJio most p:u-t, a diameter of about -^^ of an inch. As ihcy enter it 
■ they are contorted, and at their ends present small capaulca or fiask- 
shaped sacs. Each of the capsules is entered by a twig of . -^ 

ibc renal arterj-, which at once divides into loop-like branch- Mjiljptfc'hi«ii 
ca oonstituttng a tuft, and which delivers the Wood to a *"?««««• 
Tcin originating in the interior of each tuft. These structures are known 
as the Malpighian corpuscles. The vein and artery pass out of the cor- 
puscles usually at the same point ; the vein, however, instead of deliv- 
ering its blood at onoe to the renjd vein, forms a plexus on the sides of 
a urinifcrona tube, in this simulating liic mechanism of the portal vein, 
whicli begins in a capillar}* system and ends in one. It is supposed that 
the exudation of the water of the unne takes place in the Malpighian 
body, and the secretion of the solid portions from the cells whicli cover 
the urinifcrous tubes. 

The chief feature of this structure is, therefore, that in a sac formed 
upon a urinifcrous tube, a tui't of capillaries, tho walls of which are of ex- 
treme tenuity, permits water to escape from the blood supplied by the 
eanulgcnt artery. The blood, thus concentrated by loss of its water, 
passes into the vcinlets which originate in tho interior of the tuft ; those, 
converging into a little trunk, less in diameter than tlic twig rircuiMjoo of 
of the emulgent artery, escape along with that vessel trom itirUoodintba 
the capsule ; but, instead of discharging its contents info the '"^^' 
Tcnal vein, it ranuHes in a plexus on the walla of a urinifcrous tube, thus 
affording a miniatore representation of the portal vein, beginning in a 
capillary system and ending in one. From the plexus the commencing 
of the renal veins arise. 



216 



THE SLALTICIIUN COB 



ll4lfdlB|:T«n of hoouui llalptftiUii 

coryiHde, lUkgnUcd WO dUnwUn, 



Some anatomista suppose that the Malpighian capsule is not, in ToIitT, 
Fig. a. a 6ask-Iike exjuuision of the nrinifieroufl tu\f. 

but tlmt the tube, dilating, fo)t!ft over ihcUood 
cnpillarics, and so receives them. HoireTci 
that may be, they form a loose ball in its in- 
terior, fastened to it only by the arterial twigi 
and its corre-tponding and juxtaposed vtJiu 

The foregoing description is illostr:! 
the anncsed figures, JTiff, 69 being ball iIia- 
gramiuatic, from KoIliJter. 1, a Malpigliia 
capsule, A, with the tubulus uniuieru.% II, C, 
Pl>ringing from it ; a, membrane of Malpigbiaa 
body, continuous at 6 with the niembrana pro- 
pria of convoluted tubule; c, epithclirun of 
2^IaI]nghiau corpuscle ; d^ thai of tabule ; ^ 
detached epithelium; f\ vas aflcrens; ^, t» 
ctfcrcns; A, glomerulus Malpighianus: 2, tbns 
epitiielial cells from convoluted tubule, xna^ 
ficd 350 diameters — one with oU Unops. 
jPi^. 90, Glomerulus, or tuft of blood-vessels from the innermost part 
^•* of the cortex of the kidney of tlte liorse: ^ 

artcria intcrlobularis ; af, vos affcrens ; m flii 
glomeiidus ; ef\ vas cScrcns ; 6^ divisions of 
artcriola recta in the medullary substance. 

J'^ff. Ul shows the ciliated epitlielium of the 
uriniferons tube in the frog: t£, cavity of the 
urinifcrous tube ; b, its cpitlieliam ; I/, ciliated 
portion thereof; i", de- 
tached ciliated epithelial 
cell; c, basement mem- 
brane of the tul»e; c*, 
that of the capsule; m, 
capillaries of the tnft; 
f, adjacent urinifcrous 
tube. 

Jlr. Bowman's expla- 
nation of tJie Malpighi- 
an circulation is repre- 
sented in J^iff. 92. a, 
branch of renal artery ; 
af^ flflerent vessels ; m, 
in, Malpighian tut>s ; e/\ 



yi9-9\. 




THE MALPIGHIAN CORPrSCLES. 



217 



their plexus upon the uriiiifcrous tu1>c ; st^ straight 
tube; <*^ convoluted lube 

I am indebted to Dr. Isaacs for the follomg in- 
Btructive tigurca nnd descriptions from Iiis paper read 
before the Academy of Kcdicine. His method of 
examination of the iv*w- 

minute mechanism 
of the kidney, by 
rendering small por- 
tions of it transpa- 
rent, greatly facili- 
tatea these rescardi- 

iB of MklplgbUn cirea< -*-. r * • 

uuoo. 68. l>r. Isaacs s m- 

gations are entirely ronfirmatory of 
Bowman's views, so far an BJnicture 
noenied. J'^if/. 93 is a view obtained 
eitating scrapings of the kidney of a juipighiwi mn w«h nrinifrmqi luiie.^aj. 



ff^^^ 



Ituptuml JCdplebUn cull vf Um doer. m4gniacil SO dUnctcn. 



^'4 



^».%uo- 



n**l Mill c 1 call, taacvUted SQ d'.KmclcrK 



sheep (which had pre- 
viously l>ccn injected 
with chrome yellow 
and sulphuric ether) ia 
a test-tube with water. 
The portion on the left 
shows the tul't alone, 
that on t}ie right its 
rcci'ption in the urinif- 
crous capsule. 

/Vy. 94 shows the 
arter)*, filled with in- 
jection, and the 3Ial- 
pighian coil or tnft rup- 
tured in the capsule. 
The injected material 
lies in broken portions. 
Fragments of the in- 



216 



TUE U8IKS. 



jecte<l Tf'sselfl of the coil are seen pas^ng dovm the tiibo. From tLc 
kidney of llie deer. 

A diiTcrcncc of opinion prevails among anatomists as to the cxlstoncr 
of nucleated ccUd upon the Malpighian tuft or coil in the case of tlic biglier 
animals. This question is finally settled by l>r. Isxuics in the following 
manner. An ethereal or ^atcrr-colorcd solution is injected into tiie oxe- 
tcr, 80 as to distend the tubes, burst, and throw off iho capsule The 
cells can tltcn be seen upon the naked tuft or coil. jFi^, 95 shows the 
Halpigliian body and uriniferous tube of the kidney of the black beu. 
The artery had been first partially filled witli injection, which h»d brokea 
the coil in pieces. The uijection from the ureter ruptured tho capsule, 
which is seen in shreds. Nucleated cells are seen on the naked coil or tdt 
In the nppcr port of tlie figure, to the left, is a broken luft, on the right of 
which tho ruptured ca|>sulc is perceived^ and nuelcAtcd cells upon tke 
nnooTored tufL In the up|)or ]Mrt of the figure, to the right, ate tbc 
iragmcnts of a Malpighian tuft, with nucleated cells adhering to it. The 
capsule had been torn off with a fine needle. All the above drawings 
were made under the niicroseope. 

The urine of man is a clear, amber^ycUow liquid, tho average specific 
The urine ii4 g"*^*? ^f which may bo taken at 1.020, ^ving an acid n> 
I>ro|KniQ«anil action wlien first voided, but gradually becoming alkaline 
qiiAiiiii,T. ^^j turbid. Its composition varies greatly with preceding 
states of tho system, and the nature and quantity of the food. It 
amounts, in tlio course of a day, to from 20 to .OO ounces ; this, ho^vever, 
depending on the quantity of water that has been token, and on the ac- 
tivity of tho skin. Its solid ingredienls vary from 20 to 70 parts in 1000 
of tiie urine, the leading suhstaucea being urco, uric acid, lactic acid, vc»- 
icnl mucns, epithelial debris, extractive, and salts. 

The urine of carnivorous differs fi^ra that of herbivorous animals 
latter being turbid, and having an alkaline reaction; that of tiie fo 
transparent, pale yellow, and acid. 

From Winter's cxix^riincnts, it appears that for every thousand patiS 
of his weight a man discharges 25.9 parts of urine per diem, the nuu- 
imum being 46.8, the minimum 14.0. A child, reduced to the same 
standard, discharges 47.4 parts; but a cat, fed on a flesh diet, 91.036. 
The quantity of water thus removed depends, to a very greut extent, on 
the existing conditions of the system ; sometimes it is far less than would 
answer to the amount that has been taken ; sometimes, on the contrary, 
more. The solid material likewise exhibits vciy great fluctuations. 

Viewed as a group, the constituents of the orino ai-c evidently the ox- 
Orijrfn nt ihe ^'^^^^'^ rcsiducs of the system, which, unable, from their not 
possessing the vaporous or gaseous form, to escape through 
the lungs, ore, from their solubility in water, readily lemoved 



nflrrli 



otb«r urine 
coaslitueLU. 



ived 

d 



COMPOSITION OF TIIE tJRINE. 219 

Ube kidneys. The urea and uric acid arc derived from muscular do 
perhaps, of tlie two, tlie uric acid first arises, and is subsequently 
I con^-crted into urea ; this i3 not, however, its exclusive source, since tlic 
qoBxitit^' of urea increases by the use of lu^jhly nitrogenized food. The 
mucu^ and epithelial dcbria are derived from the mucous membrane lin- 
ing the interior of the urinary upparatus. Of tlic salts, there are two of 
unusual interest, the sulphates and phosphates, each having, like tlio 

IUTVA, a double origin, tlic food and tissue decay. Leaving out of consid- 
eration tiiat part wliich has been supplied by the food, wc recognize in 
tlie sulphates the final disposal of that Bulphur which was once socrclcd 
by the li\'er, and subsequently reabsorbed. In the phosphates we recog- 
L nizc the oxidation of the free phosphorus of the nervous o.netituiion of 
■ Tesicles during their period of activity. That portion of the •*"""■ 
' solid constituents of the urine which is due to decay or retrograde met- 
^ affiorphosis is shown when an animal is exclusively fed on sugar. 

H Oftiiprwiion of Urae. (From SerzeSiuS) 

H TViitor 8aS.OO 

K l-'nai 80.10 

^^^^^K Uric Acid l.oa 

^^^^^^^P Lartic ACtd, lactnUi of mnnnonia, and extractira 17.14 

I^^^^^^P Mucus .„ ^, 00.B3 

^^^^^K Sulphate of potasb 3.TI 

^^^^^H Snlpbate of soda 3.16 

^^^^^V Pbo^ihato of soda 3.01 

^^^^^^P Bi^uqihaw of ammonia l.GS 

^^^^^ft Clilwido of sodium 4.4fi 

^^^^^^H Muriate ofammoula l.CO 

^^^^^^B PlioHpliatesof lime mod msgocsla. 1.00 

^^V SUica 0.03 

^^^ 1000.00 

W The composition of urine is not only disturbed by variations in the 
aniotuit of its normal ingredients, but likewise, in morbid stales, by tlic 
appearance of unu.<!ual ones. Among these may 1>c more particularly 
mentioned sugar, albumen, blood, bile, pus, fat. The presence of such 
abnormal ingredients is determined by chemical tests or microscopic ob- 
servations. 

Since the urinary apparatus is the sewer of the system, tables, like the 
preceding, whicli purport to set forth the composition of its Variahfiiiy of 
excretion, can only be received an general illustrations. In iu contUtv. 
the urine must occur whatever materials have been gcncr- 
mted iu the complicated disintegration of the economy, and whatever use- 
less substances have found tlieir way in through the absorbents by rca- 

L son of their solubility in water. 

B Kespecting the substances thus occurring, cither normally or uiiusu- 

' ally, in the urine, the following are observations of interest: 

The quantity of urea excreted depends more upon the nature of the 



220 ORIGIN AXD VARUTIOSS OF UJIEA. 

v«ri»iioni'in ^"^^ *^'*" upoii any otlier condition. It reaches its maii- 
tb« •luantity mum Under an absolute animal diet, and its minimum uoiler 
** '"*^ a non-nitrogenizcd one It still appears during fasting, and 

fibout to the same extent as during a non-nitrogcni£ed diet. Its souraes, 
therefore, are partly the waste of the tissues and partly the food. 

By eevcral observers* urea has been delected in the blood under ordi- 
nary circumstances. After extirpation of the kidneys it has been »• 
pcatcdiy recognized in that of the lower animals. It is removed with 
Bucli rapidity b}' the kidneys that its quantity is probably never pe^ 
niittcd to exceed a tit^ieth of one per cent, of the circulatin<:; blood, Its 
origin Ima generally been attributed to the waste of muscular tis5ue, 
though it has not yet been detected in muscle juice ; but then it should 
be remembered that creatine and inosic acid may produce it during thdr 
dcaotmding ractamorphoais. Under this view, the seat of its prodactiaii 
would be the blood itself, a conclusion which is enforced by the ctrcom* 
stance tliat caffeine also increases its amount. 

In his inaugural dissertation, entitled, " Is muscular Alotion the Catuo 
OriKtn of the of thc ProductioH of Urca V^ Dr. John C. Draper, by cspcri- 
iirvA. nicuts on thc urine of jicrsons in diifcrcnt conditions of motion 

and rest, and by an examination of the diurnal and nocturnal rariationa 
in the amount of urea voided, compared with an invariablo standard, 
gives reasons for concluding that the differences in tlic amount of urea 
excreted are almost entirely attributable to the influence of llic food, an 
individual in such a Htite of comparative rest as is observed during treat- 
ment for a fractured leg not excreting by any means so much leas nret 
aa might have been anticipated when compared with another individaal 
wlio walked thirteen miles at the rate of four and a half miles nn hour. 

But, on examining the in6uencc of food, it ap]>cars to be well marked. 
The greatest amount of urea is excreted within a few hours of^cr dinner. 
Another maximum also occurs just after breakfa.st ; but during the eight 
night hours hr less is excreted than during tlie siime period in thc aft- 
ernoon. 

Tlie ingestion of food thus exercising so rapid and marked an influ- 
ence on tlic quantity of nrea, he refers to it as the cause of the increased 
excretion of that subslanco during the course of thc day rather than to 
the increased motion of exercise then indulged in; and in view of this 
conclusion, it becomes probable that the nitrogen of thc wasting niasca- 
lar tissues escapes, not under thc form of urea througli thc kidneys, but 
tiirougli tlic skin, or perhaps even as free nitrogen from the lungs. 

Of tJic variations of thc sulphates, it may be observed that the arcr- 
VBriations of ^e*^ diuHial cxcrction of sulphuric acid per thousand parts of 
ih# iiiiiih^u-s. ^H^n being 0.050 of a part, an increase ia observed during di- 
gestion, a diminution occurring during the night, the minimum being 






EXTRACTIVE AND SALTS. 221 

nadied in the forenoon. Kxerciso to a moderate dcgreo does not seem 
to inHaenoe it, though that of n moro violent kind, and also mental cx- 
dternont, do. Fasting for one day docs not diininisli it. Copious 
dnfta of water increase it, but it finbseqncntly declines. The admin- 
istration of snlplmr, and of the sulphates of potash, soda, and magnesia, 
idso inere;iR'3 it, the latter salts being removed liom the system through 
tlic kidneys. 

The quantity of extraetive matter excreted by children ia much moro 
than that excreted by adults, when estimated, as ail such Qo«ntiiTof«x- 
dbscn'ations ought to be, by reduction to a common stand- tnwtWfl'io 
ani. Thus Schcrer found that tor every thousand parts of '"^"*'" 
weight a child excreted 0.3-IG of a part of extractive per diem, but an 
adult, for each thousand parts of weight, excreted 0.166 of a part, which 
is less than half as muclu 

The quantity of clilorine in the tirine, as chlorides of sodium and ])0- 
tassiuui, undergoes many variations. Ilcgar shows tliat it v.riAtlon»i 
ia at a maximum in the afternoon, at a minimum in the th*> chlundt of 
night, and rising toward morning. Its quantity L* increased *** '"'"' 
after taking water, and then diminishes. ^luscnlar exercise also In- 
creues it. It is interesting to remark that, in inflammatory conditions 
accompanied by copious exudations, tlic chlorides in the urine are so 
nmch diminished tliat that secretion in its fresh state wilt yield no pre- 
cipitale with nitrate of silver. In SO cases of pneumonia observed by 
Hedtcnbochcr, the acidific<l urine did not become turbid witli nitrate of 
ailrer, but as the inflammatory action subsided the chlorides reappeared. 

Of medicaments and other unusual substances introduced into the or- 
ganism, those wliich arc soluble in water, and have little g^^ ^f 
affinity for the constituent matters of tlic body, arc removed »■! mIu in 
in the urine, in thia list arc found a great number of salts * * '^'°*' 
wlncfa escape in tliis manner witliout undergoing' any cliongc ; such, for 
example, as carbonate of potasli, nitrate of pota^li, bromide of sodium. 
Other substances undergo cliange previously to their elimination, as. for 
instance, the alkaUne sulphides, which become oxidized, and arc then 
finally removed as alkaline sulphates. Dr. Bencc Jones has satisfactori- 
ly shown that, when ammonia is taken, it is removed as nitric acid in the 
nrinc. Under the administration of the neutral alkaline salts of vegeta- 
ble acids, alkaline eartunates in excess appear, owing to the oxidation 
of their acid in the blood. That this is the true seat of the oxidation, 
and that it lakes place with great rapidity, is demonstrated by the in- 
jection of such salts into the jugidar vein, which very soon ore found aa 
carbonates in the urine. 
m AVhen oxalate of lime is introduced into the stomach, it docs not mako 
B ita appearance in the urine, perhaps because of its insolubility present- 



I 



I 



222 



HTPPUBIC ACID, LACTATES, PROTEIN BODIES. 



ing a difficulty to its absorptioiu In the case of some animals it occnn 
I'rMucttoQ of naturally in tlic excrement. Wlien^inmanf it iiitibandintlic 
driourbttfrJ-" urine, its occarrenoo may be often traced to a distnrbaaa 
piritioii. of the respiratory function, or 'to abnonnal metaraorpbou 

occurring in the blooJ. Under such circumstancps it presents itself in 
convalescence from typhus. That it can arise from such metamor[>lio«'w 
is proved by tlio circumslance that it is found in the urine after the in- 
jection of urates into tlic veins. When the kidneys act vicariously fer 
(be lungs, there thus appears to be a tendency to the remoml of carbon 
under the form of oxalic instead of carbonic acid. 

Hippuric acid may arise in the oi^nism from the mctamorpUopis of 
OmiTTenM) of bcnzoic and cinnamic acids, the administration of these sab- 
liippiiric add. gtnn^ea being followed by its excretion in the urine. If any 
thing was ncccssan,' to prove that the scat of its origin is the blood, its 
discovery llierein, in the case of the ox, by Verdcil and Dollfass would 
be sufficient. Its general occurrence in the urine of graminivorous ani- 
maU, and its absence in tliat of the carnivora, indicate that its nonnil 
production is connected with the nature of the food. However, among 
some of the lower animals it ii still excreted while they arc in a state tS 
starvation, and it has been recognized in the urine of diabetic patients 
under a strict animal diet. 

After the injection of alkaline Inctates into the jngular, the urine be- 
Ditappi>4nuira comes alkaline in the course of a qnartor of an hour. If 
wiM^from 'u«i ^^^y ^^^'^ ^**^" taken into the stomach, in about double that 
blood. time. The passage of other salts is sometimes even mon 

rapid ; thus the ferrocyanide of potassium has been detected in tlus urine 
in less than two minutes. 

The excess of protein bodies absorbed from the digestive canal, find 
BaocM of pro- unnecessary for the repair of the system, is rcmovofl as urea 
Min bodlu ra- and uric acid ; and, in like manner, the sulphur and i>ho»- 
"'^ phorus introduced by those bodies are, after oxidation, dia- 

cliarged as sulpliatos and phosplmtcs. Under the use of a strictly ani- 
mal diet, the urine resemblea that of carnivorous animals in color, acid 
reaction, and freedom from lactic and hippuric acids. 
DtMnpearuce '^^^ phosphate of lime often almost totally disappears 
oTphocphiiteaf during pregnancy, and fractures unite at that period with 
""'• ditHculty. 

Many circumstances regulate the length of time that extraneous sub- 
Periodtliatcx- Stances will remain in the system ; thus it sometimes occurs 
trutous »ui». that, after the administration of alkaline salts of organic acids, 
the alkalinity of the urine will disappear in the course of 
half a day, while on other occasions it will continue for sev- 
Thc period also varies very much with dilfercnt individuals. 



•Unws nifty re- 
main Id thu 

cral da^'s. 



muviduals. 



< 



I 



^Y^len the suheiance adrainistercd is of such a chemical nature that it 
can unite with any tissue, it may remain in tlic system ibr a very long 
time;. 

The anatomical constraction of the J^lalpigiuan bodies has led physi- 
ologists to infer that there arc two distinct stages in tlio sc- siamierofMs 
crction of urine. Tltcso have aheady been pointed out in urilc^i w 
the remark. Iliat the ]^lalpigliian bodies separate water Ixom oiu-Riiua. 
the blood, but that the solid ingredients arc secreted from tliat delicato 
plexus of vo-^scls which covers tlie walla of tlic urinary tubes. Before 
accepting this opinion^ wc may, however, obaor\c, that tlic cbicf solid con- 
stituents of the urine, as urra, uric acid, sulphate^^ and phospbatcs, pre- 
exist in the blood, and nre all soluble in water. It is not to be supposed 
that the water which ooacs through the delicate walls of the MaJpighian 
tofts should leave such substances bcbiiid it. That the loss of water 
•CtoaUy takes place in the tuft circulation appears to Xm proved by iho 
jact that the vessel emerging from the tuft is less timn the one entering 
it; the volume of blood is less by the amount of abstracted water. 

We must, moreover, take core tbat wo ore not deceived by a name. 
The Tcsscl emerging from the tufts may be conveniently ^^ artcriiiA 
enongb called a t'ein, but is tliere any proof that such is its .luaiitj- rctain- 
physiological attitude? Thcrc Is no reason to believe that "' '""'*'°'i*- 
iJie blood lias lost its arterial character while it has been in the tuft. At 
the most, it can only have lost the elements of urine. It is not until it 
is distributed in the plexus on the walls of the urinifcrous tubes that it 
really gains the venous charactex, and then tlirough nourisliing those ves- 
sels, and particularly the cells of their interior. 

These considerations therefore lead me to the suggestion that tlie inor* 
ganic bodies, as urea, uric acid, sulphates, and pliosphates, wliicli may all 
be rc^;arded as products of fuial oxidation, pass out with the water in 
which they arc dissolved while the blood is yet circulating in the 5lal- 
pighian tut^. The loss of velocity in t!ie current by tlic arterial twig 
breaking np into so many vessels must, as 3Ir. Bowman states, greatly 
favor tbU transudation, as does also the pressure that must arise from the 
blood having to pass tlu-ough a narrow channel of exit, and still more 
tfarongh another capillary system just beyond. It was arterial blood that 
eDtercd the tuft, and it is artcri:d blood that emerges, to be then directed 
apon the walls of the urinifcrous tiibps. 

And now the question may arise. What is the object of this second cap- 
illary circulation ? Though the statement is often made that Tim wiu re. 
the constituents of the urine arc the results of oxidation, it JS^J^J^**" 
is very far from being strictly true. The analysis of urine tunsm, 
shovB that a very large proportion of them, classed as extractive, nre real- 
ly combostiblo bodies, and not titr advanced in their retrc^radc mctaf> 




mor]>ho!ns. Tlier rctnm f^tUlf as it wctc, the traces of orgaiuxaSioa; 
they Ixtlong rallier to tliv hvilrocarbon family tluin to the nitrc^imcii 
It may lie that, for the removal of these, cell action ia nccessarr. 

"Wliatcvcr iniporfrtiicc may Iw attached to such a suggestion, it ia vcir 
Mwieofn-nior. clear that, notwithstanding the extreme thinness of the valli 
from 'ihL'Mil 0^ *hc toft vcsscls, thc rcUixation in the speed of the blood 
pi^iiUn ue. current through them, and thc pressure brought to bear upon 
them, tliat water could not be separated by oozing through them unleas 
there was an additional provision. The sac into which the exudation is 
to take place is already full, and it may be questioned whether ciliary mo- 
tion in thc urinifcrous tubes would exert a sutKcient exhaustion to relier© 
the interior of the capsule from pressure ; but the introduction of a liquid 
ot' n dirterent nature into the uriniferous tube may call at once into oper- 
ation thc principle described at page 131 as acting in tlic capillary circa- 
lation of thc blood, and thus thc contents of the Malpighian sac are drawn 
forward into thc urinifcrous tube, just in the same manner that water is 
drawn from the inside of a bladder tiirougli the jiorcs thereof by aloobol 
on thc outride. 

THE 51A5IMABY GLANDS 

The mammary glands aro situated on various portions of the abdom- 
^ . .. , inal and thoracic surfaces of animals of the class niomnialia. 

I>Mcn)itioii of 

UMsuunnivy In thc higher members of this class lliey present tJie ai^pctf- 
* ancc of racemose glands, rudimentary in thc males, bat well 

develo|>ed in thc adult females, especially after parturition. They separ 
ate from the blood the white secretion, milk. 

In the omitliorj'nchus the mammary gland consists of an obtuse com 
of coccal follicles, ending upon an areolar surface. There is no nippU 
The milk is expelled, both in these and thc marsupials, by direct mas* 
calar pressure. In cetaceans the nipple in included in a cleft of the in- 
lt» compani- tcgamunt, but in the higher mammalia it projects, so that, be- 
livcanatumr. jug received into the mouth of thc young, and suction bcix^ 
made, thc pressure of thc nir takes ctfcct upon the surtacc of thc gland 
find expels tlie milk. 

In different cases llie nnml)cr of mammie differs. In the human spC' 
cics there are but two, placed ujwn thc thoracic surface, and from their 
position favoring thc care and nursing of thc child. Among other ani- 
mals thc number seems to have a relation to the number of young lm>Qght 
forth at a birth, there usually being a pair for each one. Many excej^ 
tions to thU rule, however, occur. 

The mammaiy* gland corresponds in anatomical stmcturc to the paro- 
tid and pancreas. It consists of 15 or 20 lobes, each from ^ 
to 1 inch in width; these are composed of lobules, and these, 
again, of co.'cal vesicles. The excretory ducts arc lined with tcsselated 



J 



STRUCTURE OP M^UIMART OLAXD. 



225 







ng-n. 



thclinm. The ducts converge toward the Ttipplc, oiwiung upon it hy 
or 10 apertures, and in tlieir course dilating into unipullii-, of email 
acity in women, but in tlie cow capable of holding a quart. 

/V-s*. As regards ila development, the niammatj 

gland originates in iJie fourth or fifth ti, .uvTciop- 
month as a papillary projection of the "*"'• 
mucous layer of tlic epidermis, as shown in I^iff, 
96, in wliich 1 is tho rudiraentary gland in the 
male embryo of five months, a being the hornv. 
6» nmcouB layer of the cpidcnnis ; c, process of 
the latter, the rudiment of the gland ; </, fibrous 
membrane round it. At 2 is the lacteal gland 
of a female embryo of seven months, seen from 
above: ff, central substance of tbe gland; ft, c, 
budding outgrowths, the rudiments of the gland 
lobes. (Kolliker.) 

J^iff. 97, vertical section of the human niam- 
tygloud: «, a, its pectoral surface ; ^,/', ekin on surface of the gland ; 
c, skin of nipple ; <I, lobules and lobes of gland ; f, lac- 
tiferous tubes passing from tbe lobules to the nipple. 

As pregnancy advances, the colls of the gland begin 
to contain fat, in a manner not unlike timt which is re- 
marked in the cells of the sebaceous follicles of the skin. 
AVlien tho gland becomes active after parturition, it is 
stated that the first-formed milk-cells break up in tho 
lactiferous ducts into milk globules, their membrane and 
nucleus disapix.'aring. The milk globules arc minute 
particles, varying in their diameter from the 

tAt ^^ **'« Tiruinr ^^ »" ^"^h. They con- 
I of oily material inclosed in an envelope, as is shown by the fact that, 
Ingfa they will resist for a short time tbe action of sidphuric ether, 
n^M, they are finally dissolved by tliat suU^tance. Be- 

sides these milk globules, there arc other exceed- 
ingly minute fat particles present. The milk 
which is first secreted after delivery contauts cor- 
puscles of considerable size, and of a grantdatcd 
ap]>earance, as seen in tho photograpli, flff, 98, 
They are called colostrum corpuscles. 
They arc soluble in ether, and therefore 
I vtui oBtMtrai ffirpoKiM. contain fat. There is reason to suppose that all 
ftfiit glolmles of the milk are inclosed in cyst-like pclliclcfl of casein. 
In the chapter on food (Chapter II.), a general description of the char- 
|U(ul constitution of milk has bectt given, together with its phj-sio- 

It- ' 




link slobales. 




Cutostrum. 



226 



COLOSTRUM AXD MILE. 



pTOpcrtiM of I<>g)cal rclattonB in nutrition. It may now be added that &tth 
BiUk. milk presents an alkaline reaction, which continues longer in 

the milk of women than in tliat of cows. Left to itself, and the moie 
quickly tJic warmer the air, milk turns sour tlirough the productino of 
lactic acij, the CAsein undergoing coagulation. That the oil globulca juft 
Ajxiken of are coated with a film of a coagulated protein body appan 
from the circumstance that it may be dissolved by acetic acid, and the ia- 
eluded butter i» then set fret:. 

One of the simplest mctlioda for the analyada of milk consbts in cob^ 
Awaribor nlntiiig it at a temperature of "212'^ with pulverized gypsum; 
"»^k- the mass, being then evaporated to drjiie-ss, is pulverized, tlie 

butter being extracted by ether, and the sugar and nohible salts by hot 
alcohol. The amount of the soluble sails thus obtaine*! may be detenu- 
ined by inciiieratioii ; and since their amount is to tliat of the insoluUc 
salts OS 5 to 7, an approximate determination of the latter may be made, 
and tlicrcby the weight of the sugar and casein corrected. This is the 
method of Il&idlcn. 

It would appear, from examinations that liave been made of the sccie- 
«. 1 .. . tion of the mammary eland previous to parturition, that it 
kvtnoa «nil contains albumen in the place ot casern, the casom gramiiUy 
"^ api)oariug as the period of parturition approaches, but not 

reaching Its maximum until a few days after that event. Colostral milk 
dift'ers essentially from the subsequent ordinary secretion, as tlie follow- 
ing tabic shows : 

CauaitMtion of (bJburfixun oW JVUL {Fnm .Suaon.) 



0(»oatnim. 



1000.00 



Uak. 



828.00 


S87.<m 


fi0.00 


2AJI0 


40.00 


M..HU 


70.00 


49.20 


8.10 


S.8Q 


B.M> 


S.80 



1000.00 



The si>ecimen8 iierc presented were obtained from the same individnil; 
and from the table it appears that the colostnim contains a much larget 
proportion of solid material than tlie milk. The qnanttty of fat is neat- 
ly double ; the cjuantity of sugar is likonise much greater, but tlie rela- 
tive quantity of casein is less, this being in accordance witli tlic state- 
ment that Ihe production of that substance ajrproaches gradually to a 
maximum whicii is not attained till a few duys after parturition. 

The composition of milk varies witli many circumstances. Thus, 
VuiAbiiity in among cows, it is well known that there arc certain breeds 
iucomi«>!.iiwn. which peld a milk in which butter predominates; in others, 
a milk bi whicli tliere is an excess of casein. It is in refeixmce to this 
that such are, among agricultural people, often descnbed aa good butter 



VARIATIONS IN JIILK, 

or good cboosc cowa, as the case may Lc Such variationa arc 
ae often popularly referred to |>ccnliarilics iii tho color of these ani- 
iIb ; and, indeed, there, ia a general impression of the same kind as re- 
pots the milk of women, that that of fair women ia inferior to that of 
Bnettes. L*IIeritier, who lias examined into thia matter^ aclecte<l two 
Dalea of the same age^ 22 jeara, and caused them to a<Iopt tho aainc 
it and tho aamo mode of life. The ono was a blonde, the other a bru- 
The following tabic exhibits the moat marked of his results = 

iilB: o/" IVooKH ofi^ffcraU TenyMrdmotf*. (From L'lTeritter.'} 





Thf nk-QiK-. 


TliA Brunette. 




8jti.no 

lo.on 
4.00 


8M.30 

M.m 

71.20 












KHW.OO 


1000.00 



te average of the varioua analyses he made shows the same general ro- 
\U though not so strikingly, tlie number being for the solid constitu- 
te, in the case of tlic biondc, 120, and for tliat of the brunette^ V\4. 
Ab would be expected, tlie constitution of the milk varies greatly with 
i diet, Simon found tliat in the case of a very poor woman, induCTiiv ..f 
D had been almost deprived of tho necessaries of life, the '^"^ **" *"'"*• 
antity of solid material was only 8.G per cent. On ^ving her a nutri- 
Itt meat diet it rose to 11.9 per cent. Being airain reduced, by cir- 
IDBtanoes, to the utmost destitution, the soUd residue sank to 0.8 per 
It. ; and on once more being supplied with a nutritious meat diet, the 
pccntagc rose to 12.fi. Thcae reaults illustrate in a striking manner, 
will be presently seen, tlic function of the mammary gl.and. Simon 

found, m this particular case, that the relative quantities of ca.sein 

1 ragar do not greatly vary with these oxtreme dietary variations, but 
It the absolute quantity of butter docs. On the two occa- ^^ .^ . . 
ns of starvation, it was as low as S parts in 1000 of milk, cAwin ui4 of 
I on the two of full nutritious diet, it rose to 34 and 3T "* ""*'*'■ 
ipcctively. From this it seems to follow that while the amount of 
Mer in milk is detomiincd by the quantity and quality of tho food, the 
iounts of casein and sugar arc, to a considerable degree, independent 
•wof. and hence I believe their origin is to be attrilnitcd to changes 
king place in the system, and that tliese substances are more imroodi- 
ly furnished from metamorphoses of its structures. 

Tbc CAsein and tiic sugar are reciprocally rclatwl to each otlicr, the 
uitify of casein steadily incrcaping from the time of par- pdaiive qmn- 
ition until a fixed proportion is attained. At parturition tiiy of cueUi 
\ quantity of sugar is at its maximum, a gradual decline ""^ '^^"' 
ring until ita proportion likcwiso becomes nearly constant. 



SS8 



ACTION OF THE UA31HABT GLAND. 



Saline eiibst&noes administered hy the stomacli or rectum do not air 
ExinaiwtM ways appear in the milk ; thna the fcrrocyanidc of poiassi- 
uiu iD milk, mu^ wliich may be quickly detected in the orine, can not U- 
found in tlie milk. It ia curious, that wiien iodide of potassium has hemx 
administered to the mother, in doaes, for example, of three grains thriai 
a day, it can he readily detected in the urine of the iniant by the usual 
teat of starch and nitric aciit 

The diurnal quantity of milk yielded hy the human female has hcca 
Diurnal ^u»i». estimated at from 32 to G4 ounces. This estimate is ma/^ 
Uiy QtaiUk. ]yy determining the weight of the infant before and after suci* 
ling. Although a certain proportion is present in tlie gland, the sccre- 
lion appears to take place for the most part with great rapidity. On tie 
application of the infant the blood Bows suddenly, and the milk jttius 
into the ducts, constituting what is termed the draft. 

We now enter on a consideration of the function of the maninuir 
STwie or action g^"*^ ^*'**^* * ^'**^** of determining whether it acts in virtuf 
«f tbamuums- of ils Special construction, whether it iabricatcs in itself k]r 
ly gbuuL ^ agency of cells, the proximate constituents of milk, oi 

whether it merely strains them from the hlood in which they pre-exUt. 

Due weight should hen^ be given to the fact that, unlike tlie excretioia 
of tlic lungs, the kidneys, or even the liver, tlie milk contains a very laige 
percentage of hiatogenetic or formative bodies. Its casein can not be 
considered as in the career of retrograde transformation, sioce in the hodjr 
of the infant it is presently changed into albumen. Such a fact migtit 
even lead us to suspect that we should detect some essential su-uctunl 
and functional differences between the luommaj and other glands. 

The iuducnco of special structure is, however, disposed of by the no- 
lafianic* «f ™^oi^ wcU-authentifated cases now on record, in which poT- 
q>M^ itnw. tions of the skin, or the stomach, the navel, inteetinca, the ax- 
illa, and glands in the groin have assumed a vicariou.s action, 
and secreted milk ; and though it has been said of the latter instance thst 
it may Lc notJiing more than an ohsciuii nuuiifcstalton of an attempt in 
the human sjiecics at a repetition of tlic mammary gland in a region neai 
which it is normally present in the lower mammals, such a remark ha« 
no application in the other cases. Wc may therefore infer that the proxi- 
mate constituents of the milk arc not manufactured by reason of any 
special structure of the gland whicli secretes them, since other structures 
can assume a ^-icarions action. 

Tiiis therefore narrows our inquiry down to the point. Does the mam- 
mary gland merely 6Uer off from the blood substances already existing 
in it, or, those substances not so pie-existing, arc they made in this or- 
gan by cells ? 

Of the proximate elements of milk, many, such as tlie entire group 



SOmCE OP THE BLTTEn OP MILK. 229 

of its Baits, are acknowledgctl on all hands to pre-exist in the -jTiosaiuof 
lilooil ; and these, constituting abont ^ of its solid ingre<li- milk cxiat In 
enta, Tnu«l lie admitted to pass into the secretion by atrainagc 
only. Of the other solid ingredients, the fat, which constitutes about ono 
fourth, also exists in the blood, being derived by lacteal absorption from 
the fooil. 

IX> milk-giving animals, then, find in their ordinarj' diet a sufficient 
quantity of oleaginous mnterial to supply tlie drain establish- yj^^ i,v.irocar- 
cd through the mammary gland, nnd the calorifacient do- i«wi» pre-cxi«» 
mand, supposing none to be made in the system ? The to- "* * 
8earcht*s of Dumas have definitely settled this question. Of these the 
following ia an abridgment : 

fai M Articles of Forw/e» 

Intlinn com 8.7S percent. 

IUc« 1.00 " " 

Oa» ...,..v««,...«..- 3J0 •• " 

Ryo 1.73 " " 

■VVhcat 2.10 " " 

D17 h»y 2.00 " " 

Clorcf in flower 4.00 " " 

'\\'hcM Ktttiw 8.20 " " 

Oul straw 6.10 " " 

Beetroot 0.05 " » 

Poutoes 0.06 " '* 

A COW in good condition, eating 100 pounds of dry hay, will furnish 21 
qnarts of milk, from which there can be obtained 1^ jwunds Qn«ntityoffat 
of butter. If tins bntter was obtained exclusively from the 'oforifie. 
food, and none made in the system, we ought to lind in the 100 pounds 
of dry hay IJ pounds of fatty matter: but sulphuric etlier can remove 
from such hay 2 pounds, and in several specimens of clover cut in flow- 
er, M. Bonssingault found the proportion as high as 4 per cent. We 
may therefore affirm, relying on the universal experience of farmers, that 
the hay eaten by a milch cow contains more fat matter tlian the milk 
which she yields. Thus far, therefore, we arc not authorized to regard 
the animal as capable of producing the butter found in its milk, but, on 
the contran,', we may bo led to suppo.so that the whole of it is taken 
firom the food. 

In a physiological point of %'iew, a single experiment of this kind is 
insufficient. Errors may arise in comparing together hay taken by 
chance, and the produce of milk taken by c1)ance. It would doubtless 
be far better to establi.<?h a direct experiment, giving tlie proportion of 
butter, determined by analysis, relatively to the proportion of fat matter 
consumed by a cow. This experiment has been made on such a scale 
and with so much care as to be very convincing. It lasted for a year, 
and was conducted on 7 milch cows, the milk, dra^vn twice a djiy, being 



230 



eOUBCE OF TUB BLTTEB OF MILK. 



carefully nieasurcd. The 7 cows fumisUed 17,67G quarts of milk; iti 
veiglit was 36,382 poiinJs. Hcing analyzed from time to tunc, it wu 
found to yield 3.7 per cent, of batter, completely deprived of witrr. 
From this it follows that llieae 7 cows fixmishcd during the year 134tj 
pounds of butter. 

During this time they ate 30 pounds of hay, clover, and grass hwi 
day; that is to say, Ihe 7 cows consumed during the year 77,050 Ihs. 

Now if in 100 poumls of hay there aro 1.8 of fat» the 77,650 pouDi 
represent 1378 ; recollecting, however, the use of clover, which is riclw 
in fat, the amount should rise to more than 2000 pounds. But the hot* 
tCT obtained was only 134G pounds. 

From this experiment, therefore, we gather, that a cow wbidi is pnig 
milk finds much more fat in the fodder she eats than Is sabseqaentlr 
yielded in her butter. We may therefore conclude Umt such an auinnl 
extracts firom her food most of the fat it contains, and that she eitkr 
stores it up in her adipose cells, uses it for the production of beat, or coo* 
verts it into butter. 

In tlie argument, as thus presented by ^l. Dumas, tbe question ia cvd- 
sidcrcd in its quantitative aspect, no allowance being made, however, for 
the amount of oily material accompanying the fa'ccs, and no estimate «- 
fercd of the proportion destroyed for the sake of producing heat It 
might Ix* that the entire amount of fat escapes in the former of tliw 
ways, and that, though a soflicicncy occurs in the food, it is not Bbsori)cd 
therefrom into the system. 

There arc many facts which show tliat the identical i&i occurring u 
The idenUiMi] the food 19 actually delivered by the mammary gland with 
ii fcmid'L iho '"""J of its quantities unchanged. Thus, if hy cliance coirs 
uiUk. should e-at the tender shoots of piac-trces, or wild onions, or 

other strong^smelling herljs, the milk is at once contaminated with ik 
special flavor of their oils. The same, too, takes place when turnips are 
introduced in their diet. If half tlic allowance of hay for a cow is re- 
placed by an equivalent quantity of linsecd-cnke, rich in oil, the cow 
maintains hersrlf in good condition, but the milk produces a butter took 
than usually soft, and tainted with a peculiar flavor derived from the Un- 
seen! oil. 

To tlie preceding iaeta it is unnecessarj- to add any observations in re- 
lation to the carnivorous mnmmnl.s which obviously find in tlicir pivjr 
large quantities of fat. In tlie chapter on culorifacicnt digestion, and m 
that on the functions of the liver, the evidence was preecntexl both as 
regards the reception of oily material from tlie food, and likewise its fabri- 
SuiRciriit cation in the system. From these sources conjointly it miy 
qnuUty of fat tlicrcfore be plainly seen that fats of various kiitds must al- 
ways exist in the blood. A simple arithmeeical computation, 



J 



CASEIN PRE-EXISTS TS BLOOD. 



231 



I 



L 



>iindcLl on tlie data furnished hy the tables of tho constitution of Llood and 
tnilk rcajwctively, will show that there is at any moment a suilicicnt 
pply of fatty mottcrs in the blood to furnish two thirds of the diurnal 
ouut of uiilk. It docJ9 uot seem, therefore, philosophical, under these 
circuni stances, to ini]>ute to the niuiumary gland a power of fonning but- 
ler- It doubtless obtains that substance directly from tlie blood ; and it 
may be that those bodica which arc conceived of aa cells, and which are 
supposed to arise in the lobules of the gland in successive broods, which 
ran a rapid living career, coming into existence, reaching maturity, dying 
«nd deliquescing with incredible rapidity, are, in reality, nothing more 
than oil globules which have coaled themselves over wltli a cyst of coag- 
olatod caficin, as in Ascherson's experiment, or just as they become coat- 
ed with a similar 61m immediately on passing from the intestine into the 
lacteal vessels ; and this, accordingly, U the opinion I entertain of their 
nahirG. 

Next of the casein. There has been much contro%'crsy among chcni* 
ists respecting the existence of casein aa a normal ingredj- Reawna for !n- 
eDt in llie blood. Theoretically there does not appear any ^.llJp^^'i^* 
solid reason for denying that it may be one of those constit- tlood. 
ucnts, considering tho analogy of constitution which it shows with albu- 
men. The evidence is much more distinct and }>ositivo in the case of 
poeiporal blood, and is greatly strengthened by the recognized tendency 
to the occurrence of kicstine in the urine during gestation. This sub- 
Jtence, to which much attention haii of late been devoted, makes its &]>- 

moe in such urine sxn a tiellicle or membrane, which cradu- 
ally increases ui thicKness. it is not commonly seen before 60 
iioun} after the urine is passed, nor later than the eighth day. Though 
sometimes appearing at an earlier period of gestation, it is more frequeut 
in the seventh, eighth, or nintli months. The &ct is not without signiii- 
canco for our present purj)03e, that it may reappear in the urine after par- 
turition if any tiling occurs to check the secretion of milk. Moreover, 
Prout noticed it in the urine of a delicate child which was fed chiefly on 
milk. An examination of it shows that kie;iitinc is composed of casein, a 
butync fut, and the phoaphuto of magnesia. Such a constitution bctiaya 
at onoe its relation lo the secretion of the mammary gland. 

Xiohninnn, who inclines lo tlic belief that kieslinc is nothing el;**^ but 
the ibrmation of crystals of triple phof^pliate and fungoid and confcrvoid 
growths, whicli take place when tlic urine becomes alkaline, admits that, 
unless it has been tho basic albuminate of soda which has Itcen nn.^lakcn 
for it, cacein docs occasionally occur in the urine. Frum (lie acknowl- 
edged fact that the acid interstitial juioc of muscle 6bre contains casein, 
there can not be any doubt, I think, that tliat substance must prcHixIst 
in the blood. 



I 



SOmCE OP THE CASEIK OP mUL 

Tlie occummce of casciii undcx the form of kicstiiic in f ho tmae, in 
quantity increasing a3 gestation advanceis indicates tliereibre tliat tie 
system is assuming a propensity for tlic genenition of this subatancQ £niin 
ita albumrnold t-onipouiidit : and since, in uiscs of ston'ation, the percent- 
age of casein in tlic milk does not aecm to be matorioUy affeclcdf «c ue 
to attribute its immediate source to the B3'stem ratlier than to the food. 
In this rei^pcct it differs from the oily constituent^ butter, the {."crccntage 
amount of which is instantly ailccted by variations in the ttntnre ud 
quantity of the food. It would Bcem, indeed, that^ from the ^une phsbl 
ingredient, albumen, the soft tissues of both mother and inJant are &hi* 
cated, with this dificrcncc, that in the latter case the temporary conditiea 
of casein is intermediately assumed. ^Ve have already remarked on the 
identity of constitution of albumen, casein, and fibrin, so far as their aa- 
bon, hydrogen, nitrogen, and oxygen ore concerned ; and, indeed, thete 
compounds differ far lcs3 in their physicjil chamctc-rs from one anothci 
than albumen in its coagulated and uncoagulatcd state ; yet tiiat ditlet- 
ence iji physical quality may be readily brought about by so trifling tn 
agency as rise of temiieralure tlirough oidy a few degiv^a, and is proW 
bly dependent ujkjh tlio diHcrent allotropic forms wliich the carbon cot* 
stituent i^ 2^'^"*^ ^^ assume Uinng due weight to these vnrioos coomk' 
crations,wo shall tind reason to -conclude that this constituent of^ 
milk, the casein, is directly derived trom the system, which can manti^ 
turo it at a rate of about 30 grains (icr hour, this being about ono lislf 
the quantity of fibrin generated in the i^aiue |x^iod of time for the sap- 
port of the muscular tissues. Chemically, the transition from aibtUDCO 
to castin is not to be regarded citlicr as an ascending or declining motsr 
morphosis, but only as the temporary assuniption of a state of pasMge 
onward to the condition of fibrin. 

AVith rcsiwct to the constitution of casein there is considerable doubt 
rnmpicx na. Thc substancc commonly passing tutdcr tJiis title seems te 
tuw of c«»<.m. consist of at least two different bodies ; at all events, it maj 
be separated into two parts, one containing sulphur, and the other not; 
moreover, if to niilk,wliidi has lieen jierfectly freed from butter, thcro be 
added dilute liydrorldoric acid, tlic ordinary precipitate is yielded, b(it 
there Hiill remains in sohition nn analogons body,wiiich docs not precipi- 
tate until tlie mixture is boilccL In milk, though much of the casein is 
held in solution, much also exists in tito coagulated state, forming the 
wait of thc milk globules. Ita existence under this roembnmous fonn 
may be demonstrated by the action of acetic acid on milk globules tm- 
der tlie microscope, and also by shaking new milk with ether, which pro- 
duces very little cliange ; whcrwis, if the milk were only an emulsion, the 
ether should take up the fat and hold it in solution. Now, on the addi- 
tion of potash or its cai'bonate to milk before the action of etlior, those 





I 



I 

I 

I 

L 



THE ACTTO^I OP THE VAMHAItY GLAND. 

gQT>3lancea dissolve the membrane, and then the ether takes up the fat 
and forms a dimly-clear Rolulion. We may llierefore conclude that the 
substance we designate as casein consists of two ingredients, the protein 
compound, which exists in a state of solution in milk, and also that 
which forms the membrane of the tilt corpuscles. 

llany of the remarks just made respecting the origin of casein are ap- 
plicable to the saccharine constituent of the milk, ihc origin Origin of the 
of which is not to be attributed so much to the food directly ""f™" of milk. 
as 1o tJie system; for, in starvation, the ?ngar, like the casein, still con- 
thmes to form to nearly the nonnal amount. I think it is probable that 
its production is due to tlic liver, and is, in reality, nothing more than an 
indicsition of the continued arlion of lliat gland, ono of the prime func- 
tions of which is the generation of saccliarino compounds. 

Fron» the data now Iwfore us respecting the origin of the different con- 
stituents of the milk, the casein, the butter, the eugar, and ^^ mnmmarv 
the salts, we are able to come to a definite conclusion re- Ki<in<i «< u by 
garding the physiological action of the mammary gland. 1 '""°°' 
have entered on this long disquisition from tlie important bearing wliich 
the decision we arrive at has upon the whole tlieory of secretion^ for if 
there be a gland in tlie body in which we ahoidd expect to iind proo& 
of formative power, tlirough the agency of cell life or otherwise, in giving 
rise to products that did not prc-exLst in the blood, it is certainly the 
mararaar}'. But now, as it appears tlist all the constituents wliich its 
secretion contains are found in the blood, wc can scarcely suppose that 
the ^and itself does more tlian merely strain them out; of course, in com- 
mon with all such stmctTires, it possesses what might aptly be termed 
an elective liltrating power ; thus it permits the exudation of the iodide 
of potassium from the blood, but refuses a passage to the fcrrocyanide. 
And, finally, the conclusion to which we thus come recalls the remark 
hcrctotbrc made, thai the more thoroughly we sludy the secretions deliv- 
crod by the various glands, and the more pcrt'octly wc identity tiie sources 
from which their constituent ingredients have been derived, the more wc 
should be disposed to impute glandular action to the physical process of 
elective filtration* and the less to tlie agency of cell life. 

OF TUE SiaJJ. 

The skin is composed of two layers, the epidermis or cuticle, and the 
derma or cutis. It contains two systems of glands, one for the removal 
of water, and another for tluit of oily substances. It also presents sul^ 
sidiarj' parts or ap|)enilage3, audi as the nails and hair. 

The epidermis, which is the exterior portion of the skin, originates from 
the cutis. It has a ditFcrcnt tliickncss in ditfercnt parts; TheepWermUi 
the contiastt in this respect, being very well shown upon thu *" structurfl. 



S34 TUE B£TE MCCOSCU AMD TH£ TBLE fiKlX. 

solca of the foet and tlic cvelida. In this respect its use is mcclianicaL 
It Ben*es as a protective covering lo the parts it envelopes being thici 
^vhere pressure and liard usage have to be provided for, and thinner wlicre 
there is a necessity for motion. It coiiBists of an aggregation of undo 
atcd p.iTticIes adhering together, the deepest being grantUes, the intrr- 
znediato more perfect celU, which gradoally become flattened scales ii^ 
they ai*u examined nearer the surfice. They undergo constant exuvia- 
tion, and ore as conatantiy rephiced from beneath, the supciticial odu 
becoming drj- and homy, thus furnishing a resisting ti^ment, the oper- 
ation of whicli is very well displayed by the action of vesicating agents; 
a watery diecharge from the vessels of the cutis soaks throngh llie loircr 
Btibatance of the cuticle, and raises the dry layers above. The cbeminl 
composition of these dry scales is the same aia that of nail, hair, horn, 
and is C,^ II^^, N,, 0,g. 

At one time it was Hup[K>5cd that the rete mucosum, or layer of 3Ial- 
Title niucoium P'S'"» ^1*'^^' '3 the lowcst portion of the cuticle, and tbcrt- 
uid iu coiur- forc rcsting on the cutis, is a distinct atracture. It is, ho1^ 
ngtDAtur. fiycYy merely the most recently-formed portion of the cuticle 
The netted fippenraiicc it |>rcscnt3 originates in the eminences of tlie pip- 
illary stnictnro below. Many of its constituent particles contain eel* 
oring matter, csjx?cially in the dark races. The pigment seems lo U 
produced by the agency of the sunlight and continued high temjieniluie, 
though it di^aji^iears gradually as the ccHh containing it approach tbe 
surface. It yields a vciy hirge percentage of carbon. 

Beneath the epidermis is llic derma or true skin. It is comjxiscd oi 
_. , fibrous tissue, which also senea to connect it with the parts 

Um-ooBtruc- bencfltli, blood-vessels, Ivmphotics, and nerves. In its areolii 
°* tissue both the white and yellow fibrous elements are found, 

the proportion of each vnrj'ing according to the mechanical fanction Ac 
part has to discharge, the yellow predominating where elasticity ia re- 
quired, and the white where a resistance to pressure. The derma abo 
contains organic muscular fibres, to which its property of corr :. u 

^^ in cutis anscrina, is due. On ditl'ercnt parts it is of difFcrcui ..a, 

^^p being thinnest where motion has to be provided for. A deposit of fatt^ 
^^^ material, lodgcil beneath, gives it a yielding support. Its outer surface 
I presents a papillary structure, wliich is the instrument of touch. This b 

I more ]>erfectly developed on the inner surface of the palm of tlie hand and 

I fingers. The furrowed aspect of the cutis arises from this. A farther 

I consideration of the mechanism and functions of the papiihc is deferred to 

I the description of the sense of touch. 

^^^ The photographic engraving, J^iff. 99, represents a thin section of the 

^^M epidermis of the foot of the dog. 
^^^ The general method of arrangement of the constituent portions of the 



THE CCnCLE. 





Ftff.Mn. 




^I/Umrmlt «f dag, magtUdnl iO dUmctm 



PcrpoDdleiiUir wctton of nkin of 



ikin may bo gathered irom the perpendicular section of that of the cx- 

Kmal auditor}' meatus in 7*'/*/. 100, a, the derma; i, reto mucosum ; 

L liomy layer of cpiJcrma ; t/, coil of ccruminous glands ; f, their cxcrc- 

Dry ducts ; J", tlieir apertures ; ^, hair-sacs ; A, sebaceotts glands ; V, 

Uases of fat. (Kolliker.) 

/'tff. 101 shows the under sorfaee of the cuticle detached by macera- 
ion from the palm, cxliibiting double rows of depressions, in which the 
ipiUa: have been lodged, i\'itii the hard epithelium lining the sudoripa- 
ducts In their course through the cutis. Some of them arc con* 
,cd at tlie end, where they Irnve enteral llic sweat gland. (Todd and 

Bowman.) 

J^ff, 102, papilla; of the 
palm, the cuticle being de- 
tached. (Todd and Bow- 
man.) 




^^^m man.) 



I-kpUtK 

Jf'if/. li'ut suriacc of (he 
skin of the palm, showing the 
ridges, ftirrows, cross grooves, 
and orifices of the sweat - 
ducts. The scaly texture of 
the cuticle is indicated by the 
irregular lines on the surface, 
(Todd and Bowman.) 



336 



THE KAtLS AXD HAtB. 



Tbeuili. 



The Nails constitute one oftbe appendages 
of the cpidcrma. They are homy 
coverings protecting tlic extremities 
of the fingers and the toes. They originate 
in a fold of the cutis, and become firee at their 
outer extremity. The nail grows fi^m its 
roots, inciOAsing in length, and simultaneously 
in thickness. Its rate of growth dei>emlaupon 
the general rate of nutrition. Ouring peri^Mla 
of sickness or ahstincnce, ita ^Towth in both 
directions is retarded^ as is indicated by a mark 
or impression on its sor&cc, and so titc nail 
becomes a register of the condition of nutrition 
during the period of its own existence. The 
thumb nail is said to occupy about 20 weeks atoofiui«.m.s«K!ad»di. 
in ita growth firom the root to the extremity ; that of Ihc great toe abont 
two year* — an estimate which is probably too long. 

The Hair, — Each hair originates in a flask-shaped follicle, formed ly 
. a depression of the cutis, and lined by a continnation of the cu- 
ticle, and, like it, prcsontuig scales on its sujMirficiea and round 
cells beneath. Tlic bottom of the follicle is the place of origin. Tlie 
hair consists of two portions, the outer or cortical, and the inner or me- 
dullaiy, the proportions of which differ very much in different cases. 
The surface of the hnir presents a layer of imbricated scales, within which, 
at the lower port, arc minnio cells, but further from the root the cells bo- 
come larger and begin to contain pigment, the coloring matter being dift- 
iributed unequally, sometimes producing a tubular apitcaranoc in the am 
The hair grows by constant prolongation from 
the follicle, its color being due to a peculiar col- 
ored oil ; and in the black varieties, iron predom- 
inates. The diameter of tlic hairs varios irom 
tH^OtteW <><■«" inch. 

In Fig. 104, the structure of the root of a hair 
and part of its shaft is displayed. Bnlb of n 
small black hair from the scrotum, seen tn see- 
tion: rt, basement membrane of the follicle; i, 
layer of epidermic cells resting upon it, and be- 
coming more scaly as they .ipproach e, a layer of 
imbricated cells forming the outer lamina or cor- 
tex of the hair : they are more flattened and com- 
pressed the higher they arc traced on the bulb. 
Within the cortex is the proper subetance of the 
hair, consisting, at the base, where it rests on 



rijj. It* 



IW-i 



m 



■<3, 



Uttnuw bslr In netloR. 



J 



OF THE SUnOniPAEOUS OLAXDS. 



237 






i boAeaent membrane, ot* small angular cells, scarcely larger than their 
nt- uD>- nuclei. At d these cells are more bulky, 

and the bulb consequently thicker: thero 
is also pigment developed in tlicm ; above 
d they assume a decidedly tibrous char- 
acter, and become condensed ; e, a mass of 
cells iu the axis of the hair, much lomlcd 
witii pigmeut. (Todd and Bo>vmau.) 

/i«/. 105 is an engraving of a pboto- 
gi'aph of a transverse section of human 
hair from the head. The outer liuc 
shows the cortex ; in some the pigment- 
ary axis is seen ; in most, however, it is 
absent. 
The SUDOEIPABOLS Glanus originate in depressions of the cutis or 
beneath, occurring in some parts, as in the axilla, Tj,p Bn.iori|wi. 
numerously than in others. They consist of a tubo wnijlaml*. 
on ilselt", and sometimes dividing iu convoluted branches. The 
^t Xlius arising is contained in a cell, the wall of which is copiottsly 
tappUcd with blood-vessels : the duct passes through the superjacent tis- 
sues. The tube is formed of a cylinder of kiscmcnt mem- 
brane lined with epithelium. The basement membrane 
may be considered to be derived from the outer surfaoo of 
the papilla?, and the epithelium is an external projection of 
the cuticle. The duct, on its passage outward, loses its 
basement mcmbrano as it escapes between the papllhu; 
and it has a spiral or helical aspect, an ajrangcmcnt prob- 
I, ■■ ably intended to keep the calibre open. It is estimated 

that the number of sudoriparous glands is about seven mill- 
ions, and the total length of their tubing about 28 niilos. 

J^i^, lOG is a sudoriparous gland from the palm of the 
hand : a, a, knot of tubes with two excretory ducts, 6, by 
uniting into a helical canal, wliich perforates the e{}iderm!a 
at e, and oj>cns on its surlocc at d : the gland is imbedded 
in fat vesicles at ^ «, «, «. (Wagner.) 

The SuUACEoLS Glands are distributed in different 
d*np»TOo.[ti»ad, abundance in various parts, their office being tIic M-brtooot 
to lubricate the hair, to keep the skin in a flex- si""''- 
condition, and avoid the inconveniences of frictioiu Their ducts 
, either into the hair follicles or upon the cuticular surface ; the gland 
ioDsisting of basement membrane Uned with epithelium, the cells of 
'ich, as ihcy reach maturity, become filled with a sebaceous or oily ma- 
Thc car glands of this class secrete a waxy matter. 



288 



OP THE SKBACE0C8 OLASIW. 



Suclt being tbe construction of tho Axa^ m'^ hart next to speak of iti 
action. It dischiu^ics a double function: Isl, as an excretino;, and. 3d, 
a.s an absorbing or^an. In this respect it has an analogy with thcnm- 
C0U3 membrane, vhich, indce<l, ia a reflection or continaation of it. 

Of tho excreting action of the skin. The skin pcnnits water, saline 
IHflbmntktntU 1^^ ^^^^7 Bubstoitces, to cscapc from it in quantities wliidi 
oriMi»i>iraU(«. differ on dilTercnt portions of its surface, the nature of the «e- 
cretions varying to meet local TC<}uircmcrts. In the cxarninatiun wlucli 
vc are now entering upon, we shall sjK^ak of these Bubi^Ianccs and their 
proportions in a general way, oveilooking, for the time, the particalarv»> 
nations. Yet that such rarialions exist is clear on the most superfidal 
observation. The sweat of tlie feet diflers from that of the general nu^ 
face, as, again, does tliat of the arm-pits. 

It has been usual to distinguish tho watery tmnsndntion into two pev- 
QuftDiliTof tion*. tbat which escapes from the perspiratory ducts, and 
water thrDiigh tliat passing through the surface of the cuticle- 1 1 has crtu 
from tint duel* ^*" ^^ *'^*' ^^^ *"*** glandular secretion passing from tbe 
oinpucd. ducts is not more than one sixth of the total cutaneous be* 
udfition ; but this, I believe, is altogether erroneous. When we renll 
the im[K!rmeable nature of the homy and dried scales whieh constitute tb 
outer portion of the cuticle, and that these arc constantly coate^Uivcr witli 
«n oily vantish issuing from the sebaceous gland >>, we may infer that tk 
cutaneous surtace bctwccu tl e mouths of tho perapir.-.tory ducts is coo- 
stnictcd rather for the hinderance of evaporation than for its promotion; 
and though the oily matter with whicli the skin is thus imbued is justly 
regarded as having for one of its functions the prevention of injury fron 
the a<lmission of cxteninl moisture, it must be equally ettectual in stop- 
ping (he escape of water from within. Tho tardy manner in which »»■ 
tcr thus escapes is illustrated by the operation of biisters. 

Under tlic form of steam, water continually e^icapos from the akin. It 
E h iatk>a '^^^ ^^ Certain occasions, issues in the liquid state as dro|is 
mnd ptnplra- of swcat. To its cscapc undcr the form o( steam the desig- 

* nation of exhalation or insensible |)crspiration is given ; but if 

under the form of sweat, that of sensible perspiration. 

Of Kx halation. — On condensing the vajwrs which arise from the 
skin, tiicy arc found to consist of water containing a little acetate of am* 
monia. With the water likewise csca(>es carbonic acid gas. W^ith a 
view of ascertaining the weight of the matters thus lost, Seguin inclosed 
E Mr' me In ^^'"s*^^ '^^ ^^ air-tight bag, the mouth of whicli was gummed 
to lUK-cruia iJitt upon his tace in such a way as to pcnnit the access of air to 
^r w«[^ng*' **"' i^l'iratory oi^ans. Ho then determined the weight of 
tbrou^^h Um his lx>dy and the bag together. After several hours, on re- 
weighing, he ascertained the amount of loss hy pnlmomBiy 



J 



OP PEESriRATIOTir. 



239 



I 
I 



I 



I 
I 



exhalation. Then, taking off the air-tight bag, ho was weighed again, 
and after another interval once more. The difference Iietwecn the two 
last weighings is the amount of tlie pulmonary and cutaneoiiis exhalation 
together, and from these data, by a simple arithmetical ealeulation, tlio 
value of each may be determined. By these experiments it appeared 
that the lo83 by pulmonary and cutaneous cxJialation togetltcr is, on an 
average, dghteen grains per minute, of which seven issue from the lungs 
and <:Ievpn from the akiu. The variable action of the skin is, liowever, 
well illustrated by the extreme numbers observed, the minimum Ijciug 
eleven grains, and tbe maximum thirty-two. From the experiments of 
Valentin, the average of loss through the skin is two pounds and nearly 
half an ounce a day. Seguin's experiments would make it two pounds 
and three quarters. It has been shown in Chapter X. that (.„^of (1,^ 
the action of the skin is partly meteorological: the amount ^nri»Me«aon 
of water passing tlirough it depends on the dew-point, the '^ " "^ 
atmoaphcrie temperature, the conductibility and pcrviousncss of tbe cloth- 
ing. Whatever physical circumstances promote surface evaporation cor- 
rei^iondingly promote tJie action of the skin, iloreover, this membrane 
acts Wcariouflly with the kidneys, and this not only as regards the water, 
bat also as reganls the solid matter, a large amount of which is thrown 
off in the course of the day. 

In all computations of the r[uantlly of water eliminated by tlie skin, 
it sliould not be overlooked that any hiclosing barrier or bag must neces- 
aarily occasion a complete alteration in the conditions under wliich the 
action ia occurring. On the whole, it is pcrliapa most probfihle that the 
ratio of the matters expired through the skin and those expired by the 
lungs is as 9 to 5. 

Besides the water secreted by the sudoriparous glands, carbonic acid 
and nitrogen escape. Their relative proportion ia variable, Tmn-piratioo 
and seems to depend, among other things, upon the nature of ^f «*>*»• 
the food, tlie carbonic acid increasing under a vegetable, and the nitrogen 
under an animal diet. From the experiments of Dr. J. C. Draper, above 
xeferred to, it appears that the absolute amount of tlicse gases is inilu- 
enoed by exercise. 

Ok Perspiration. — Wlien the atmospheric temperature is liigh, and 
more |)articularly if muscular exertion be resorted to, tlie H^^mlients rf 
quojitity of water issuing from the perspiratory ducts is so i>«»f"r*L''"i- 
great th:it It can not be evaporated. It then exudes as drops of sweat, 
which become mingled with the oily secretion prepared by the scbaceons 
glands. From this commingling it is scarcely possible to obtain the 
sweat, in an uncontaminated condition, suitable for analysis, or even to 
exclude the detritus of the cuticle itself. In a thousand parts of sweat 
there are £rom five to twelve and a hali* parts of solid matcriaL Thcnard, 



I 




EXCUKTION OF FAT BT TUE SKIK. 



by reflOTlin); to iliG cxjwdiciit of woaring for Bonie tiars a flannel shirt 
which bad been tborooghly wnshed in dLitiUed water, ascertained, aficr 
it liad Again btien waaliod in distilied water, tltat it Iiad become imboai 
witli the chloride of sodiuni, acetic ncid» phosphate of soda; phoisphate of 
lime, oxide of iron, and an anttual snbstanco. Bcrzolius found in the 
sweat of the forehead cldoride of Hodium, lactic acitl, and muriate of in- 
inoaia. Jk'sidcs tlicse, otlier cliemi.sts liave found butyric acid, the ca^ 
bountcs and sulphates of potash and soda, and the carbonate of liia& 
That sweat contains sulphur is proved by keeping a [nrtion of it: wbea 
putrefaction ensueSf the sulphide of ammonium is disengaged. 

Fountroy first detected ureu iji jie-rspirution, on observation SQ^St- 
qucntly contirmed by Landcrcr and others. That the skin can, under 
certain circuinstanccR, excrete urea, is proved by the interesting &ct thit 
this substance sometimes occurs as a blui&h powdery material on the 
bodies of those who have died trom cholera. 

In the perspiration formic acid also exista, and in certain conditjou 
opCTin-Min) of *^^ disease, as, for instance, intermittent, it occurs in connd^ 
furmic acid iu crublc quantity. Its origin may be from lactic iKid, vhidt 
penpiratiou. puggp*, through tlus combination in gradually proceeding t0 
its final destruction into carbonic acid and water. It has been asBertei 
that the increased acidity of rheumatic sweats is due to a conoentratioD 
from evaporation. 

The sudoriparous glands Becrete a portion of fat, as is demonstrated by 
ETpcrimcnt of the experiment of Krause, who removed liom the jwilm of the 
UnuMM. hand, on which there ore no sebaceous glands, loose cpithe* 

lial scales and fat by means of ether and friction, and then placed upon a 
square inch of it several thicknesses of filtering paper, which was kept 
in contact for one night, and projjerly protected externally. The papci 
yielded to tho action of ctlicr a fatty substance, whicli contained nuugs- 
rine and oil, in quantity suflicicnt to make tissue paper translucent. 

Bat, besides tho saline substances thus dissolved in water, tho akin, 
SirmtlonofrAt '^r*^"J?'^ ^''*^ action of its scbaceoas glands, sccrctcji olcagin- 
nnd oil from ous matcHaL Tlic nature of this fatty substance differs on 
I ic » m. diflertmt regions, or according to the purposes to which it is 

to be applied. Where the ducts of the sebaceous glands open into the 
hair folhcle^, the fat is of a Uquid or oily nature. Sometimes stcanne 
and margarine, sometimes choicstcrine is set free. Before birtli, tliis last 
substance is the chief constituent of the veruix cascosa, coating the sur- 
faee of the skin. In this manner, sometimes the sapouitiable and some- 
times the non'Saponifiable fats or lipoids ore used. 

In the midftt of tlieso complex actions a very important principle may 
Doable «p|lon he disccmed. I have spoken of tho double action of the kid- 
ney, its mcclinnism for removing saline solutions, and also 



of the (kill. 



^ 



ABSORPTION BY THE SKHf. 



241 



t for comLustiljle nintcrial. I hnvc now to present the skin nnJcr the 
aspect. It is not a mere analogy that exists between the action of 
organs ; the occurrcitce of urea and of the salt substances, the namcft 
whicli havo been specified iji botti secretions, ia a tact of the utmost sig- 
lific^nfjp. T IxUieve that the sudoriparous glands are tlie counterparts 
f the ^lalptghian bodies, and the sebaceous glands, in their function, aie 
bo counterparts of the urinitcrous tubes. Indeed, this double action is 
1I50 ilLatinguiuhed in the case of the mucous membranes, which possess 
mo instrumental arrangement for the transit of saline solutions, and an- 
itliCT for that of fats. And since the skin, the mucous membrane, and 
fae great glands connected with it, arc all to l>c regarded as developments 
€ one original tissue, we b1iou1<.I expect to discover, even in their coiicen- 
ntfion or 8)iccialisation of function, the traces of their origirml and eom- 
Bon projH'rty, Development take.s jil;iiv» from tlio genenil to tlio special ; 
uid hence, in parts which have arisen from the same primordial structure, 
hough they may bo charged with the accompUshment of functions which, 
npliearance, differ essentially, tl»ere may be, both in their action and 
their construction, tlie traces of their original identity. It is in this 
net that the kidneys, and skin, and mucous membrane, possess the 
>pCTty of acting vicariously for one another. The kidney can dia- 
water for the skin, or the skin urea for the kidney. The com- 
itiblc matter, known as extractive in the urine, can be set free under 
inishod renal action by the sebaceous glands, and the saline solutions, 
iminated by the convoluted tubing of the tufts of Malpiglii, can be set 
le by the convoluted tubing of lite 8udori]>arous glands. In connection 
irilh the views I am here imprcssmg, 1 would recall the structural and 
Rinctional analogy tliere is between the transuding mechanism of the 
Itidncv and the transuding mechanism of the skin- Both arc arrange- 
lAcnta of thin convoluted tubes, and the same may be remarked as re- 
pirds the elimination of combustible material, which is probably accom- 
plished by cell action in the urtnifcrous tubes, and again by cell action 
D the scbacoowt glands. 

Besides exercising the functions of exhalation and perspiration, na- 
tteroos facta demonstrate that t!ie skin exerts an absorbent AbMriitionb/ 
tction. The cnderniic application of remedial agents eatab- afgaanuad 
\hes (his in a snth^tiictory manner. That water can find UiiuiJa. 

in this way is shown by the assuaging of the thirst whicli may 

on taking a batb ; nor is the amount insignificant, since it may 

TC rise to a considerable increase of weight. Thus lizanls, which have 

kept in a dry atmOi*phere, and thereby suffered a diminution, recov- 

their original weight aitcr immersion in water; nor ia it necessary 

the whole skin should l>c brought into contact ivith that lic^uid ; 

mc result ia obtained if merely the tall and hinder parta ore im- 

Q 




242 



PCRCTI0N8 OK THE SKI5. 



xnersed. Gascons substances also 6nd entrance tlirougji the skin. If 
the hand be pnt into a bell-jar containing oxrgen, nitrogen, or carbouc 
acid nt the pneumatic Irougli, absorption of those gases ensues, l^roba- 
bly it ia a standard tiinction ol'thc akin to permit a partial artcrializatioa 
of the blood, atmospheric oxygen being exchanged for carbonic add 
through it, an action the residual trace of the community of function )»• 
tvcecu the skin and mucous mpmbmnc. In the case of some auiuials 
this cutaneous respiration is well marked. 

Recapitulating now tho more im|x>rtant actions of t!ic skin, the foUov- 
Sommirr of *"& statement may be made : It regulates, to a certain extort, 
Ui« tunciioas tlic amount of water in tlic system, disposing of it, as the cue 
of the »kin. jjjj^y 1^ either as sensible or insensible transpiration. Tie 
water doubtless maintains its liquid condition until it presents itself tx 
the mouths of the sudoriparous ducts, moistening the general surlitue of 
the akin, and then being evaporated ; or, if the snpply be gixuitcr thin 
can be thus removed, it accumulates as drops of sweat. There appein 
to be no substantial reason for believing tlut any portion uf water tmu- 
adcs directly tlirough the structure of tlio cuticle, since the scaler wtiicL 
compose it are of on impervious and almost horny nature, and their ti^ 
terspaces are fortilicd against any such leakage br the oily exudatiooB 
of the sebaceous glands. With tlic water thus presenting on llie eur&tt 
are many compounds which arc also constituents of the urinary scoe- 
tion. Among these, urea may be j>articularly pointed out, thus indicatii^ 
a similarity of instrumental action between this organ and the kidneys, 
and lliis is farther substantiated by both conlaining provisions for the 
elimination and escape of the hydrocarbons; but besides these direct 
functions there are other very important collateral agencies which the 
skin exerts, and particularly us a regulator of temperatnrc- In tliis re- 
spect tlic action is, to a certain extent, mcteorologicah But tliis has been 
previously treated of so much in detail that it is unnecessary lo zesmne 
the consideration of it now. 




SECAT AND yCTKinOX. 



I 



CH.U^TER Xni, 

OF DECAY AND NUTRITION. 

mfi Zamm of llVjAl «i» Stiirvttliott. — Inlenttiiuil UttUh. — Effeei of AUotn^Um. 

^Xutritiim : Nutrition/or Hr/Hiir and y»tritumjbr Hemedeiiii}/, iUttttrated in the coMtt tjf Fni 

OKi/ lioitf rrfftr^rtirf/i/. 
<y /Vrf / Ita J\ra/tttHtira, motkt of Orfttrrtncr^ and Orufih, — iMjviry whrOter Animai* rrtrform 

fat. — Artitiriai J*rotlwtinn of it. — AainuiU both eoUect it <md nmit it. — AcnumUatwit of it 

nay—A Sitrvyemseti Tittve. — drndilioHM tf lAe FalieKin<f of AhimaU. ~~ SumtHonf (fttid 

Sourot t , Ijf}Mmt, tatd mcotnrt of' Remwai of Fat, — It* partial Oxidations.- — Summary of ita 

t-^Ktm^—J^ntftmisa/ SMtrition. 
qf Borne: Thf ^>ivitta». — Stmetmrt and Oumtcai ComfMtititm <fIione. — SomTeea ofita Com- 

atittmU, — TV J-VortM o/" Oinfifiratinm. — I^/KriiiKntM on (ho Grovth of Sonc—'IiifliiaKt rf 

/Hj/mval A^tnts on iJcifciopmatt uftd Aofn'/wn. 

or DECAY. 

The aninia] mechanism, as a condition of its activity, is constimtly 
gtrii^ rise to wasted products, its parts iri eucrpssion passing „ ^ j 
throng rctrofp^dc mctnmorp!iosi3 or df^yiy. From the clab- niciaiuorpiio. 
orate organization which they have maintained, they go by *'*" 
degrees through a descending course, whicli brings them nearer and 
nearer to tlie inorganic state. Tims the liits, foiling from one step to an- 
other, finally emerge from tlio system as carbonic acid and water, and 
thus tlie complex atom of protein degenerates into those substances and 
ammonia. 

To this steady wasting away we offer no resistance. Having no in- 
terior principle of conservation, the organism delivers itself Lom of weight 
up unresistingly, and, if its necessary supplies be withheld, 'i»'«"»"oo. • 
very soon succumbs. The experiments of Chossat show that, taking the 
mean of forty-eight cases, including rabbits, Guinea-pigs, turtle-doves, 
pigeons, hens, and crows, tiie Iwdy loses 39.7 per cent, of its weight be- 
fore death by starvation ensues ; that mammals, during the process of 
inanition, lose daily 4.0 per cent of their weight; and birds, as indeed 
might be expected from their higher rale of respiration, 4.4 per cent. It 
follows, therefore, that sacli animals, under these circumstances, lose one 
twenty-fourth part of their weight per diem by destniction of tissue, a 
reaalt wliich corresponds with tliat of Sctmiidt's cxj^eriments, which lead 
to the inference that the daily amount of properly-selected foo<l wliich an 
aiumal requires must amount at least to one twenty-third of its bodily 
Wright. 

That the functional activity of a part implies destruction is very well 




S44 



I^TTERSTITIAL DEATH. 




iUastrated hy tlio grfldual waste of the maples under use ; that nerrcis 
K*eeHii}- of activity is al^o (Ifpeudeiit on oxidation is indicated by the 
repair. nppcaranoc of alkaline phosphates in the urine Gencnlir, 

tlic more active tlic function, the shorter the life of a part ; but even the 
hair, the loetli, the cuticle, the activity of which is very low, are no n- 
cepliuns, for they, too, have a limit of duration, and provisions for repair 
or renewal. Thus, as the surface of the cuticle ahmdes, it is restored b\' 
the development of ncxv cells below, and their gradual drying up into 
scales ; and as reganls tho tet;th, the second set arise, as it may be Esid, 
firora germs which have been left by the first, bo that when the ctowq of 
tho deciduous tooth dies, and its fang and vascular arrangement ore sIk 
sorl.cd, the new tooth is ready to take its place. 

Sinco it is not merely snjierficial parts, as tho Iiair, tlic teeth, or llic 
Int«nUUal cuticic, but aUo the dci.]>-scatcd or interior ones, that undergo 
detUu these changes, the appropriate designation of interstitial deaJh 
lias been introduced. The removal of the efictc material is accompIisK' 
ed by the aid of tlic blood, which occasions partial or jicrfect oxidation, 
willi a corresponding liberation of Iieat, and tiicn, dissoUing tliC prodncts 
that have arisen, carries them away. Wo have heretofore discussed tlic 
question how it is ttuit this osudizing action of the arterial blood is lim- 
ited to the dying parts, and hotv those which arc yet capable of tokinga 
share in organization arc protected. It appears to me timt we are obliged 
Dcravdrpmd- ^° admit, in the mechanism of living beings, those peculiar 
rut on allfttrop- conditions which both simple and compound bodies mayu- 
sumc, and which are known as allotropic states in chcmistij'* 
The indifference to oxidation wliich carl»n, under the form of diamond 
presents, contrasts strikingly with the extreme combustibility of lamp- 
black. The ready oxldibility of phosphorus, which causes the ahlmng 
from wliich it has ilerivcd its name, is no longer recognized in that other 
phosphorus whicli has been acted on by tlie more refrangible rays of tho 
sun. And these are qualities which elementary atoms carry with them 
when they go into union with other bodies, as is %\*p11 displayed by tlw 
two ili^tiiict forma of i)hosphurcted hydrogen gas, bodies having the 
same composition, but the one »|M>ntnneously eombustiblo and tlie other 
not. Some reasons have also been otVercd for imputing to tlie nervous 
system a control over these allotropic changes, and under this point of 
view we must regard it tm having, for one of its prime duties, the Ha- 
lation of decay. These conclusions receive weight from the considera- 
tion tliat in plants, in the economy of which no interstitial deaths arc 
taking place, no nervous system is found. 



USE, SOVRCE, AND DEPOSIT OF FAT. 



245 



I 



OF NUTRmOM. 

Interstitial death and retrograde metamorphosis imply removal ; but, 
l»eaides the rcmov;ds oi' wasted material, ou account of its in- N'uuiiion for 
ability to be any longer substirvient to the uses of the econ- [J^'|*J[| ^rn^ 
omy, there are also subordinate removals, which are con- modeliag. 
nected with the necessary remodeling of parts. Thus, during the growth 
of the skeleton, Lone cartli is transferred from one point to another, tlie 
ta cavities enlarged or altered, and the substance taken from them 
IS wirried to otlier points where it is needed. Under sucli ctrcunistanccs, 
the disa]>pearing jnirt is not, iji reality, giving rise to useless products. 
The substance thus taken from the {)Osition it occupied is as valuable as 
it ever was, and accordingly it is employed over again. 

The restoration of. material in the place of that which is being con- 
nuned for use, and even the preservation of excesses which may be of 
ralue at a future time, is very well illustrated by the deposit of fat in the 
adipose tissue. Transference from jwlnt to i>oint of material which has 
undergone no deterioration may be studied in the liistory of the growth 
and development of bone. To these coses in succession I propose to 
direct attention. 

I*^rst. Of the use, sources, and manner of deposit of the fat. 

The use of fat in the animal economy doubtless depends on its heat- 
making power ; for, though there arc man}' ditferent varieties rni.vMoioKieai 
of tliia substance, solid and Uquid, they are all characterized "Jitwnsaf fiit. 
by an analog}' of composition, all containing a great excess of unoxidized 
hydrogen. It is, indeed, on this pecnlinrity that their employment in 
domestic economy depends. Tlicy arc all highly combustible, and evolve 
so ranch heat as to be very available for tlic production of flame. 

Kor the better understanding of the functions discharged by fatty sub- 
stances, we may perhaps protitaUy ofl'cr tiic following statement of their 
chemical relations. 

When a fit or oil is acted upon by an alkali, in contact with water at 
its boiling-jKiint, deconifwsition ensues, a fatty acid and gly- (;.i,^,„i_j _. 
ccfinc btnng disengaged, and the acid, uniting with the alkali, diiiaritiMof 
gives origin to a soap. During this action no oxygen is ab- 
sorbed, but, since the compounds arising present an increase of weight, it 
is evident that there has been an assimilation of water. In view of these 
iacts, it is therefore inferred that the oils and fats are com]>oscd of a fatty 
acid united with the oxide of a radical, to whicli the designation of lipyl 
has been given, and which, when it is displaced, combining xvith water, 
gives origin to glycerine. 

Glycerine, which is a substance of considerable physiological import- 
ance, ia a pale yellow liquid, of a sweetish taste, and attracting moisture 




24G 



rBOPEKTIES OP FAT. 



iToin the air. If ferinented in a large quantity of water witli yetst, it u 
converted into mctacetonic acid. It occurs in tlic yolk of the tgg^ ud 
ftlao in tlic iats of tlie brain. By gradual oxidation it can give riao lu 
lactic acid. 

TiiQ pliyaical properties of the iats depend, for the most part, ou tbc 
nature of their acids. The fats derived from animaU arc of various du- 
gTce» of conaistency j they are colorlcsa or white, ii;j;iiter than u'ater, W 
conductors of heat. They arc insoluble in water, and bum, in the pm^ 
encc of air, into carbonic acid and water, with the c%'oIutiou of much heat. 
Uy tlie action of certain nitnigenized femienta tlicy may be separated intu 
tlicir acid and glycerine, ond by the action of pancreatic juice, as «- 
plained previously, may be brought into the condition of an emnlskn 
The more important of the animal fats ore stcarine, maiganne, and oleiBC; 
riftcMofoerar. Thcy are inclosed in cells accumolatcd in vairiotts parts of 
nnce of f&L (Jiq system, such OS in the orbit of the eye, around the bent, 
and among the muscles of the face, under the cutis, and within the bono. 
In morbid states they sometijucs abound in the kidneys, liver, and spleeo. 
They arc also discovered in some of the animal tluida : thus they conunn* 
nicate to tlie chyle its characteristic property, and therefore likewise oc- 
cur in the blood. In their relative nnioimt thcy vary at dificrcnt periods 
of life, being in a larger proportion in childhood, and again after the mid- 
dle period. Their quantity likewise changes with physical changes, di- 
minishing, for instance, alter continued muscular exertion, and also hf 
long exjwsuru to cold. 

Though the amount of fat in the blood varies with the nature of the 
QMatitTuftai f*^^ it can not, however, be increased, in a state of health, 
la the blood, beyond a certain point, owing to the inability of the absorb- 
ents to receive more than a definite quantity. The serum of arterial coo- 
tains less fat than the scrum of venous blood ; the blood of women more 
than that of men. 

The manner of occuirencc of fat in 
organised structures is twofold : oft- 
en it occtu's in the free state, but also 
is very commonly inclosed in the in- 
terior of cells, as shown in /'i*/. 107, 
which is a fat-^cll, a being the adi- 
pose membrane, and £ the nucleus. 
I^fj, 103, adipose and areolar tissue: <^ a, fat- 
ccUs ; ^, 0, fibres of areolar tissue. 

Respecting the origin of the fat substances in 
Fats «rian from plants thcrc Can be no question. Thoy 
Md^JeTil "^ Jerivcd from the decomposition of ^i'l^"^*^" 
tutoititf ibwnto. carbonic acid and water by those onranisms under the in- 




^(Lltt, 



r*i-«uiL 




J 



AirrmciAL fobmatiox or fat. 



247 



[cncc of the rays of the sun. It is interesting to remark that to these 
■me binary bodies do tlic fats return after accomplishing t!ic successive 
tftgtrs of thtir metnmorj)]iosi3 in the economy of animals. From car- 
ionic acid and water they come ; to carbonic acid and water they return. 

Dut the origin of the fatty Buhstunees of animals is by no means bo 
Icar. One of llie questions which Iiavc been debated in eliem- j. . 

eal physiology is. Do animnls collect from their food all the roiiertorfab. 
ftt they require, or have they the power of making it for tliem- ^'^*'*'^ '"^ 
eJvcB f in the preceding chajiter, under the description of the origin of 
be butter of milk, we have, in part, anticipated the facts which might 
lere be presented. Referring, therefore, to what has there been said, it 
rill be fiufticicnt now to admit the general conclusion that tats and oils 
neT7 abundantly occur in plants. 

. But instances are not wanting which show that from other sources 
Bian the vegetable kingdom, and by processes very diiTercnt to those ex- 
icnted by plants, fats may be made ironi substances in which tliey did 
lot pre-exist. We select some of lliese whicli liave been offered by chem- 
Bts who have asserted the power of the animal system for such a form- 
Uion of fat. 

Ist. When an nnim:d body is buried under certain circumstances, it 
■oes not undergo putrefaction, but changes into a fatty or soapy 
nbetancc, adipoclrc. Attention was first directed to this fact *rKa<x-> ofiu 
m tb<^ occasion of exhimiing many bodies from the cemetery f*^'""**"- 
>f Innocents in Paris. Those wlueh lay a certain depth beneath tjic 
^and were found to have undergone the change in question; but that 
i docs not altogctlicr dejxind on the condition of tlic earth of the grave, 
kB respects moisture or other such physical state, 1 have myself liad the 
^yportonity of verilNnng in tlie ease of a subject whicli liad been buried 
for nineteen years, and whicli was disinterred in a condition of perfect 
■eaervation, so far as exterior ap[)carancc went, bat which had been 
rholly converted into adipocirc. Yet, from the same bm'yiug-groun<I, 
butny other Indies were disinterred, but none had undergone a like change. 

2<L When nitric acid is made to act on fibrin apparently deprived of 
its fat, an oily substance is disengaged. 

3d. Puring the action of nitric acid on starch, in the prcj^nration of 
oxalic acid, a like effect takes place, oily matter being set free. 

4tli. ^Vs lias been described in a preceding chapter, butyric acid may be 
prciiarcd from sugar, through the intiuencc of casein, in the presence of 
Barl>onatc of lime. 

Thongh the conversion of albumenoid bodies into fat has not thus far 
distinctly accomplished in an artificial way, no doubt p » ji _# 
exist that it is possible. Indeed, the experiments of bt (VtMn ilbD- 

;uain and Virchow respecting the origin of adipocire have °'™*''* '»*^«*- 



248 FORMATION OP FAT UT AKOUJA 

led them to regard it as, at all CTCtits to eome extent, arising from l!»c 
albuminous coixstitucnts of tlie mnsclcA being dccooipoAcd into latty adds 
and atnmoniocal salts. Wagner, Donders, Burdach, ond others have fv- 
nifilicd many interesting experiments on the apparent tranamntation uf 
various bodies, sueh as pieces of coagulated albuineu» crjrstallinu Icnsrj, 
etc., in the abdominal ca\ities of birds. These extroncotu objects altera 
time become enveloped in, and in some easea T>crraeatcd bjr, fatty mate- 
rial. But that tliis (!oej not arise from mctamorjiho^s of the protein 
body introdaccd was well provetl by the last observer, who cmpliW 
pieces of ivood and the pith of cider with the Ranie result 

Whatever, therefore, may be the conclusion arrived at on the cases 
Tlis carniroTB ^*^"^ introduced — ^whether, during a Kpecial mctamorpbons, 
HdJ ffttintiirir muscuIar tii5BU0 can pass into adi{>ocire ; whether from lihrin 
or starclt, by the action of nitric acid, fats may be made, or 
whether these substances pre-existed in the material from which tlier ap- 
pear to arise, and are only disengaged or set free — thertj can be no (jnestioa 
as regards one great group of animals, the camivora, that they iind in their 
food a sufficiency of these hydrocarbons to meet all their wants. It is 
03 respects the other group, the herbivora, tliat this question of the arti* 
fieial fonnation of tats from substances in whidi they did not prc-cxiat, 

n ^ , ,, and particularly from albnmcnoid bodies, becomes Interest- 
Do Lha liorliiv. * , ,' , ■ < i • i • ,* i n i <• 

or» «rw make ing. Do the herbivora find m their food all tlic fat they re- 
"^ quire, or arc they obliged to fabricate a part? 

The question whether there exists in the animal mechanism a capaUl- 
Fonnation of ity of forming fat from material in which it did not pre-exist 
Cu by beet, jj^y Ijq considered as finally settled in the affirmative, after 
much, discussion, by tlie repetition of GundL'laeh's experiment by Uumas 
and Milne Kdwards. This experiment consisted in the feeding of bed 
witli honey nearly free firom wax, and determining the quantity of fatta 
their bodies at tiie beginning and end of the experiment, and also tlie 
quantity of wax in the comb that they made. The following table giTtt 
the result : 

Gnunnok 

Fat found in ibe body of each Ivc at tlio boginiunft 0.0019 

Wax each bee cun<4uincil with Uia honof, not exceeding r^ 0.0003 

Wliule amount uf fut derived from fuod .O.OOSS 

Wax secreted by each bcc 0.0064 

Fat and wax in the bod/ of each bea al end of experiment. 0.0013 

From which it appears that a very large quantity of iat and wax had 
been proiluccd. 

Admitting thus that tlic animal system possesses the power of form- 
Tho wrtttm ^"^ ^'' '' *^ probable that, under all circumstances, it carries 
eonUnuaii/ forward tliat function, though it may be at different rates on 
gcncraua at. jiffgy^nt occasions. Such a production of fat probably com- 



n-AJm? rcTi!<isit fat, 



2i9 



nonces in tlie iiitestinol tulje, the material from wliicli it originates Leing 
>Dtli nitrogcuized and non>nitrogenizcd. Thus, when ducks have been 
bd on albumen containing hut little iat, the digested materiul in tlic in- 
testine yields a larger proportion of fat than when they have been fed on 
iav» or even on starclu lithe glands of the intestine secreted fut from 
he blood, it would ho detected after feeding the birds with clay, and 
tence wo may conclude that the source of the increase observed is from 
he albumen. 

But, in addition to the part they thus make, a large portion of the fat 
pf aniinaU is undoubtedly obtained from the food. Tliis is obviously tlic 
BOkSC with carnivora, and the same may, indeed, be said of the Iicrbivora, 
BFcry many of the oleaginous bodies have a close chemical relationship 
lo one another, so that they may he regarded as atlbrding a series, the 
terms or mcmljors of wliich arise from successive partial oxidations; 
ind since the tats are soluble in one another, tliey freely mix together, 
kiid tlierefore many of them may be found co-existing in the adipose lis- 
IDcSf some of them less and some of them more advanced in their prog- 
ieas of oxidation. Whetlier Ihey have been derived from rinnw furnish 
file food or by indirect processes made in tlio system, it is fat '"■ ii't iu«to- 
tqually true m lx>th instances that their primary source was -whitli itU 
in the vegetable kingdom. In the former case they occur- ^"'"'"' 
ted in the plant-structure as hydrocarbons, in the latter as amylaceous 
or nifrogenized bodies. Under tlio influence of ihe sunliglit tlic vegeta- 
ble tissues obtain Ihem by decomposing carbonic acid and water, and to 
those two substances tliey return after they have undci^oue destruction 
in the animal organs, thus jircscnting a significant instance of the alter- 
Ikftte passage of atoms from the inorganic to the organic state, and back 
•gain. 

Tito primary source of all fut substances is therefore in plants, which 
ohtain ihcm from the decomposition of the iiiorganie constituents of the 
air. The excess of iiydrogcn which characterizes this gronp of bodies in 
most instances is undoubtedly derived irom the decomposition of water, 
«nd this explains the fact, frequently noticed, that the development of 
imcli hydrocarbons in plants is often accompanied by the simultaneous 
Rppearance of acids, for tlie hytlrogen being appropriated by the former 
class, tho residiul oxygen gives origin to acids or is set free. 

The quantity of fatty matter formed in the ordinary articlcii of food 
Used by domestic animals seems to be amply auJhcient to Quntiivorfat 
meet all tlicir wants. If a calculation l>e made of tlic amount '? ^'IV'" "t^' 

_ OH-nt IVT ULI- 

of snch materials consumed by cattle during the process of mal*. 
^ttening, it will be ascertained that the quantity used not only contains 
Bufficient to account for the increase of weight, but also furnishes an ara- 
supply for the portion which is destroyed by respiration. Tiic fata 



250 cosDmOKS OF rxn^sino. 

thus contained in plants are often absorbed with but little nltcntion. 
Tlu: fattening of cattlu with linsced-cokc gives rise to an acciuuulalion 
in tiieu* adipose tissues of an oiljr material of unusoal iloidir^, aail it ia 
a matter of common obser^'ation, as previously mentioned, that when 
Btroug-smclliiig oils have been accidentally used, tlieir flavor will be tin- 
parted to the secretion of the mammary gland. 

The quantity of fat in articles of food is commonly catimatod br ibe 
solvent action of sulplmric ctiier. It shoultl, however, be umlerstooil 
that we can not with correctness regard all the matters extracted bv thxt 
menstruum from plants as fat. 

Thns, cither by forming or by collecting from the food, a supply of fit 
Tho accunialft* is obtained, and this is absorbed by the lacteal ^slcm in tiw 
quilrs nuL-'*^ manner olroady described. I!ut where fill is administered 
gniiiced ttMim-. in exccss, SO tluit large qnantitie-s of it arc retained in tbo 
Byatcm, a proportionate cell formation arises for the purpose of affording 
it a receptacle. The walla of such cells arc composed of nitrogcnind 
material, and herein is displayed the connection between tho two gniiips 
of bodies, tlic albnmenoid snbstancc and tlio tats. There is reason ts 
suppose that wlion, from tho food, a sufficient quantity of nitrogcniznd 
material for thia purpose can not be obtained, resort is actually had to 
the muscular fibre of the system itself, but when this also fails tbe£u 
accumiilale-s in tin; blood. 

In the nrtiticial fattening of animttls, the indications to be complied 
r.«n»r«l rontii- wllh arc very obvious : They are, 1st. To furnish an ahand- 
HucVmgdflL '^^^ Bupply of oleaginous material in the food; 2d, To pre- 
liiisi*. vent, as far as possible, waste by oxidation. 

The first indication is satisfied by the purposed employment of oloag- 
inons articles, as, for instance, tinsccd-cakc, or by the selection, arooi^ 
ordinary food substances, of those which, like Indian com, abonnd in oil 
It 13 to be remarked that the increase of weight of an animal may take 
place in two ways : 1st. By adding fat to the deposit in the adipose tis- 
8ue3; or, 2d, Hy development of the muscles. It miglit i^rhajw Ijc ad- 
missible to 8[>eak of the former as adipose fattening, the latter as albo- 
mcnizcd. According as it has been subjected to one or other of thees 
processes, an animal will be very differently prepared for underling se- 
vere exercise. A liorse fed with Indian corn can not, under those cir- 
cumstances, maintain liinisclf as well as if ho had been fed on oats. In 
the former case his adipose tissues have been developed, in tho latter hi» 
muscular. 

The second indication is met by resorting to every expedient which 
can restrain the action of the respired oxygen. A state of perf(?ct quies- 
cence is therefore to be oljserved. Muscular movement of even,' kind in- 
crcasca the actiWty of respiration. On the contrary, rest diminishes it 



BOURCEB, DEPOSIT, AND KEMOVAL OF FAT. 



251 



, in addition to this state of quiet or rest, sleep likewise he indulged in, 
'■ object U still more perfectly attained; und ii'a high temperature be 
orted tOf since this checks the oxidation needful for maintaining tho 
f^stein at its due temperature, this also diroinislics tho vaate of the fut. 
Under Bucli circumstances, where every thing is done to givo a snpply 
of fat, and every thing to prevent its consumption, it may bo caused to 
accumulate in tlic tissues to an cxtxaordinory amount. But Th^,]|„rafli,ce. 
tiud very soon interferes with tho action of the hver, one of <kI in Umt opcr. 
lite funcliona of which we have seen is the preparation of fat. *^'""* 
ftnd it may also be remarked timt many of the diseases of that organ, 
■pcciaUy those occurring in hot climates, meet their explanation on the 
principled we arc here inculcating, the state of rest produced by lassitude, 
the wami and therefore expanded air that is breathed, and the improixjr 
resort to olcaginons articles of food. 

Inificw of the preceding facts, it may therefore be concluded that the 
interior source &ora whicli tho adipose tissues are suppUcd summa of 
is th& ClL contained in the plasma of the blm^d. into which it ibe fourcct, 
been poured through tlie thoracic duct, or otiienvlsc ob- ™s""an,iman. 
icd from the digestion of food in the small intestine ; and "" «>' removal 
ice the bliwd-ccila contitin a higher percentage of oily ma- 




than the plasma (2.2 per cent, may be extracted from tliem by ether, 
as a pbosphorizcd fut or glyccro-phosphoric acid), they constitute 
iCMiToirs of supply to meet the exigencies of tlio system, there being a 
ry relation between the quantity they can thus retain in store 
quantity contemporaneously existing in the plasma, a diminution 
ich at once establishes a drain upon the cells. Thus cliargcd with 
hydrocarbons, the plasma passes wherever there arc adipose cell- 
fumishing to them the special nutriment tliey reqtiire for tlieir 
ipmcnt into fat-ccUs, the wall and nucleus of which are derived from 
iood, or, as wo Iiavc mentioned, in certain cases actually from the 
;r tisBuea. The amount of fat which can thus be held in reserve 
ids in part on the number of germs, in part on the supply of fet 
the digestive organs, and in part on the supply of appropriate ma- 
erial tor tlie walls and nuclei. 

When tins fat thus stored up is wanted, tho cell wall in mouy cases 
IdUqucecca or wastes away, surrendering its contents back to the plasma, 
Rit |irobably much more frequently a transudation of the Jiydrocarbon 
ikes place through it, analogous to what has been described as occur- 
ing in the blood-cells tl»^mselvcs. TIiis demand npon the adipose lis- 
nes may originate for many reasons, since there may be a necessity for 
It in the accomplishment of the various histogcnetic operations going 
bni'ard, or for those of retrograde metamorphosis, or for the maintenance 
i a normal stale of the blood as respects its oleaginous ingredient, or for 




S53 



VMS OF FAT. 



tlie production of heat by immediate itnd jinal oxidation into carbonic 
acid and wntcr. 

It is not to be supposed, however^ that this iinal oxidation into car- 
Tuu amUtaa bonic ncid aiid water always takes place at once or abrupt- 
il""»*l»"iiio* 'y* Kvcry tiling kUgwa that fats p:is« throiigli succesiiw 
ty^um. gradations of retrognide raetAmorphosin, perhaps gradtuUr 

losing by oxidation two atoms of carbon and hydrogen ; and, iniM 
tJicrc is reason to believe that, on special occasions, the opposite chan^ 
happen. Thus stearic acid may arise from moigarie acid by deojcidatioa. 
It doeii not occur to any considerable extent in T^etablc tbod, lulling 
tJi'.is far been only found in cacao butter. 

In a summary of tlie mses of fatty substances may be mentioned tb 
SmimarT' nf production of a high tempcratun? by oxidation ; tht^ir 
ihe uvM of fat. ij^ metamorphosis, as displayed by the assistance th. 
in gastric digestion ; the function they seem to discharge in cell life, 
which would appear to I)e important if it l>c tnie that tbe nuclei of some 
coUa are composed of fat; tlnir relation in the formation of bile, and tlrir 
probable connection with the production of ba>matin. Among their phjs- 
ical uses may be mentioned ti^c equable manner in which they propapito 
pressures in all directions when they are in the liquid slate, as is oitcn 
the case ; the manner in whicli they fdl up vacuities, and communicate b 
roundness and solidity to tlic system ; their low conducting power « 
respects heat, which enables them to economize the warmth of the body; 
their diminishing of friction among moving pali:^, aa in the case of the 
muscles; and that they discharge some highly important fimction is 
respects the nervous system is proved by the manner in which they 
uniformly occur in tubular nervous tissue. In the gein'ral njelamorjJi- 
oaes of the system they seem to take an im|K)rtiint part. This mit 
be inferred from the fact of their presence wherever ccdls or fibtrss an: 
forming. 

From what has been said resjjccting the connection of the fats nitli 
the metamorphoses of the system, it is obviously incorrect to regard than 
as constilutiug a purely rcspiratorv' clement. 

Conclusions similar to tliose which have been stated ro^pectlng tlie 
Niitriiinn «f ^'^gGtal)lc source of the fats might also be arrived at as ic- 
tho niiTnt;rn- gards the source of the nitrttgeuized constituents of the sys- 
""■ teni. These Likewise are found in plants; and thus, therefore, 
though thii camivoroiLi aninial may be said to be nourished by the car- 
cass on which it fccils, it is n overt he le-ss strictly true that its nuttiest 
material is all from the ye<:retable world. 



1 



The repair of muscles, of nerves, of the skin, or other such highly or- 
ganized parts, is dependent on the agency of cells. Since these are iin- 
distinguishablej or to all appearance perfectly alike, it becomes o matter 



^ 



fiTBrCTLTlE OP DOXE. 



S53 



I 



I 

I 



I 
I 






of curious inquiiy how they sliouU bo able to occupy Pxactly the plaoea 
and discharge with precision the t'lmctions of those which tliey are re- 
placing? or, in the case of grow'th and development, why they should 
combine so as to take on a determinate, and, as it were, predestined form? 
How is it tlrnt such a variety of structures spring up from the same orig- 
inal cell 1 How is it that the two halves of the body have such a syin- 
metrical conformation in a majority of instances, the one being the exact 
counterpart of tlie other, peculiarities which arc often continacd even 
after the supervening of morbid conditions, as shown in such cases as 
arc kuown by the term of symmetrical diseases, in whidi a structural 
dianyc afiirting one side of tlic Iwdy affects also tlic corresponding j>art 
of the other side ? It appears to mc that these and other such instances 
of nutrition, growth, and development can only be explained by admit- 
ting, as a great and fundamental principle in physiolog)', that the primoi"^ 
dial germ })cing in all instances alike, its mode of development will de- 
pend on the physical agents and conditions to which tt is exposed: a 
principle whicli, tliough it may seem of little moment at the first view, 
carries witii il consequences of the utmost iun>ortancc at last 

Second. Of the structure and development of bone. 

Tlie skeleton in man is composed of -4(5 bones, which are usually di- 
vided into three groups, the long, flat, and irrcRular. Their „ 
uses are purely raeclianieal, such us to give Bup|K)rt to the 
soft parts ; to serve as levers on which tie muscles, by their contractions, 
may act. 

In structure bone offers an imperfect division into the compact and 
spongy. The compact is, however, a poraus mass full of cells structure ot 
and passages. Through it there jass, mc>re particularly in •'"""• 
the lonmtudinal direction, cjinalsfbr containinj; blood-vessels and nerves: 
th^ are called liaversJan canals. These, which are well seen in a thin 
transverse section of bone as irregular circular openings, are surrounded 
with lamclhr, and in the bnsia substance occur hollow spaces, the lacuna', 
whicli, presenting a dark asjifict, were formerly mistaken for solid corpus- 
cles; tlicy arc, however, caviiiesfrom which proceed minntc channels or 
canalicuii. In form the lacuna* are irregularly oval ; the canaliculi of 
those nearest to the haversian canal coinmunicatc directly with its cav- 
ity, and there is so complete nn inosculation lictween adjacent lacunir, 
by means of these delicate tubes, that the whole so-called compact struc- 
ture of the bone may be said to present a connected system of loeuiun 
and canaliculi. 

The diameter of these delicate channels of intercommunication is much 
too small to permit tho passage of blood-cells, yet through them the 
plasma readily finds its way and thus carries forward the nutrition of 
the entire boiie. . 



2M 



COMPOSITION or DO.VE. 



I^ig. 109 is a photograph of a trans^-erse Bcction of part of human de- 
mur, showing the haversian canals surrounded by their concentric lamel- 
lie, lacuna?, and canalicuU. The complete perviousness of the stmctorc 
is demonstrated. 



Taimnrm MoUoa of bonv, nucalfiM M dluavlMii Lm^oni ud ewMUeull bom OnnUl 1mm 

Fig. 110, lacuna' and cannlicxUi of human frontal bone. 

In chemical constitution, bone may be considered to be composed of 

Chamlcal ewn- *^** portions, organic and mineral : the former ift gluten, oqJ 

posIUonof in the latter phosphate of lime greatly predominates, as the 

following analysis by Bcrzelins shows : 

AnntyxU of liotie. (fiorsefiiu.) 

CortilA^ (or gluten) 8S.17 

BIood-TCAM:U 1.18 

FbM|ihatc or lime £1.04 

Carboiuitc of Itme 11.00 

Fiouritlo of t'aU'itim • 8.00 

Pho«ph*te of nm^caift , 1.1S 

Sodfti cblorub of sodium • l.iW) 

100.00 

An instructive soparatinn of bone into its leading constitnents nSyl 
Rrnantlonaf accomplished by the action of hydrochloric acid or by cal- 
itM-rganic «nd dilation respectively. "Wlicn a hone is soaked in dilate hy- 
t-wriiv UM. (Jrochloric acid for a due length of time, its mineral constitu- 
ent is removed, and the organic gluten is left in the shape of the ori^nal 
bone ; or, if the bone be calcined in the open tire witli free access of wi, 
the organic material is consumed and the mineral material remains. A 
nntre critical examination shows that tlicsc constiments are not mcrdy 
associated together — they are^ in reality, chemically combined. 

The different degrees of softness and Iiardncsa which bones fri>in dif- 
ferent auinials present depend very considerably on the amount of wa- 
ter they contain. The gluten is doubtless, in all iiustances, derived from 




OF OSSIFICATION. 



255 



melamorphosis of albnnicnoid lioilics, a conclusion which ^ . . . , 
well illustrated by what we observe iu the case ot" the in- organit unA 
.bating egg. In the. adult llie source of the bone-earth is ^"''''^ ""'^**'"' 
ofohl: in part it is derived from the food, and in part obtained from 
c remodeling and changes of the bones themselves. In S|jeakirig of 
ic composition of milk, wc have already described how, through the ca- 
sein of tliat secretion, a supply of pliosphate of lime is secured for in- 
Ij&nt life. 

At its tirst formation, bone consists of a gelatinons material, which grad- 
Bally becomes condensed and cellular, presenting what is termed the carti- 
Bginous state. In this material vascular cimals arise, which, jy,^ ,,nK*w> of 
Bonccntrating toward one spot, give origin to the point or fMiiinuwn. 
jentTD of ossiHcation. Simultaneously, the structure of the cartilage be- 
iomes modified, its nucleated cells are elongated, nucleoli arising, and 
Snaller cells forming. These reach maturity, and are separated fi-om 
jne another by the material derived from the deliquescence of their pa- 
icnt celU, which has simultaneously been taking place. The progress of 
these changes may be studied by examinmg the calcifying cartilage near- 
sr and nearer to the point of ossification, to which, as wc approach, wo 
ind that the cells become more and morc numerous, a general arrange- 
jient into a columnar fonu being now apparent. 

The deposit of mineral material commences at the point of ossification, 
ind proceeds between the columnar arrangement of cells, lateral bronch- 
B8 between the individual cells lx;ing successively given off, a bony net- 
work thus arising which is pervious in every part. In tlie human em- 
))ryo the cartilaginous stage is completed in tlic sixth week, and ossiH- 
Bation commences first in tlic cla\ncle during the seventh, 

J^iff. 111^ perpendicular section of the ossifying 
border of the shaft of the femur of a child a fortnight 
old: «, cartilage in whidi the cells, the nearer they 
arc to the ossifying border, are in moro extended 
longitudinal rows; ^, ossitying border: tlie dark 
streaks indicate the progressive ossification of the 
intercellular subgtancc, the dear ones the cartilage 
cells, which ossify subsequently; r, compact layer 
of bone near tlu3 ossitying border; (I. the substantia 
spongiosa formed in the osseous substance by ab- 
sorption, with cancclli, f, t;, the contents of whidi are 
nut shown. (Kollikcr.) 

I^iff. 112, photograph of ossifying cartilage, the 
dark jiortions showing the region of complete ossifi- 
cation. The columnar arrangement of the cartilage 
ellfl is very apparent 



FSfi.iU. 







856 



OROWTU OF DONE. 

n-j. lit 



/>t. Its. 



> 



X 



c 



OmUriK fwmmr. 



OmlTylm^ cKnn&gv, tBcgnlflad 30 dUiuctf«> 

Fiff. 113» femur of a child a fortnij2;lit oIJ, natu- 
ral size : 17, substantia coTn|>acta of tbe shaft ; 6, 
tnedullnry ca\'ity; r, substantia spongiosa of the 
shaft ; (/, cartiinginous cjiiphysis, witli vascular ca- 
nals; 0^ osseous nucleus in the tiiferlor cpipliysis. 
(Kollifcpr.) 

When silver rings are placed upon tlie shaft of 
Growth nf a growinry bone at a measured dis- 
i3wrioB°iui"a ^^'"^ subsequent examination shows 
nuddcr. that tliat distance still remains the 

Bune, though the Xmne may hare become much 
longer. If such a ring !« permitted to remain a snf^cicnt period of tine. 
it will eventually be found in tha interior of the bone. When moiMer 
13 mixed with tlic food of pigs, its coloring matter so unites with the 
phosphate of lime of their bones as to impiut to them a red tint. If the 
animal submitted to the ex]wriment be very young, the whole skeleton 
may be tinged in a single day, a more close examination showing, how- 
ever, as might be expected, that the portion most completely acted upon 
U that ncai'cst to the va.«cu]nr surface. In older animals the coloring 
goes on more slowly; the portion which shows the effect most striking- 
ly is Ijctwcen the shaft and extremities, more particularly upon the sur- 
face. If the madder be given jwriodically and then withheld, alternate 
layers of a red and white Hp|>aarancc are produced. 

From these experiments, it may Iks inferred that the growth of a bone 
Condwioni is not uniform in all parts. Young bones grow chiefly toward 
•BSTcjfperi- ^^^ extremities ; nor is the growth cumulative, the porta al- 
menu. ready doj)08itcd being ever after preserved ; for, if that were 

the case, it would not be possible for a ring placed in such a manner as 
has been described to find its way into the medullary canal. Kor that to 



JM 



d 



OP JomuTiox. 257 

r, tliere must have Lecn an abBorption or removal of the pre-existing 
. The liiigiiig bv madder shows that growth is taking place wher- 
tbe plasma of the bluotl can luivc access, and this nut alone upon 
e projKjr vascular suriaccs, but also inlcrstilially. 
It thus Appears tliai bone, solid and dense as it is, is the seat of con- 
tinual changes, which, though they may go on with more activity in the 
■growing state, take place also when the structure has reached maturity 
or apparent jwrfcctioii. IVom one portion a piu-t is removed, on another 
oJtlititins arc made, the method by which this is accomplished being 
■through the access of the blood-plasma, which &nds its way to every 
part l>y reason of the pennons structure of the mass. 

As to tiic sources from which the phosphate of lime is derived, though 
■doubtless the food offers it in considerable nnantity, there are „ 

r -.,. . , ,.»., . ,., Souncci from 

many reasons lor interring that the identical portion which wtikfiraaierUI 
iiaa been removed from one part is used for the extension " '^''""•^* 

■of anotlior; and tlins wc may say that there is a plastic operation con- 
tinually going forward, a rcmodelmg, so as to adapt the structure to its 
jicw conditions if in a growing animal, or to maintain it in good repair 
[f in an adult. 

Turning from the two cases with wliich we have been thus occupied, 
ihc development and maintenance of the adipose ajid osseous tissues, to 
Ihc phenomena of nutrition generally, wo may conclude that tlierc are 
peveral sources from wliieii material for tlicsc purposes may be derived: 
ft jMirt may be obtained by absorption directly from the food ; a part may 
be manufactured or fabricated in the system itself, or may be taken from 
pome locality therein in which it has become redundant or useless, and 
Iransferrcd elsewhere to the |>ouit at which it Is required. 

The roediura through whicli these additions and cxcliangcs for the pur- 

Knie of development or remodeling are accomplished is of course tlic 

|Ht>od. It bears with it, wherever it circulates, the substances tliat are 

■demanded — fibrin for muscles, bonc-carlh for the skeleton, fat for the ad- 

iipose tissues. 

It remains for U3 to inquire into the laws of deposit and development 
involved in these processes, that is to say, why, for example, p ^, j 
|s phosphate of lime laid down at the points where the phos- v«-ioii(-ri and 
phate of lime has been, or, if growth be taking place, why [hc'^,tiBcnM 
are the accretions aiTanged in a definite way both as respects of i.bvsioU 
size and shape ? Upon this inquiry I do not pro^iosc at pres- 
ent to enter, since it Is closely connected with the general doctrine of de- 
velopment, which will have to be considered in detail in the next book. 

pVe shall then find (hat reasons may lie assigned for the deposit of given 
substances in places that have been vacated hy others of ihc same kind, 

_*s in the nutrition d'mafcles. ^^'c shall also then have to consider the 



^58 



OF THE NERVOUS SY8TESI. 



laws of development from a much raoro extensive jioint of view, intro- 
ducing the doctrine of the paramount tntlucncc of physical Cttiiscs inihia 
respect, and perha{>8 vc s^liall find ourselves brought to the conclusioD 
lliat the pro^asive care*;r of a ccU is ahaohitcly dependent on the (ilirs- 
ical conditions to wliich it is exposed^ and tliat there is uothiiig extnor- 
dinar)' in the circunislimcc that two cells placed under conditions which 
arc alike will develop alike : that, therefore, a part which is being repiintl 
will have its additions made iu the same places, of the same materiiLto 
the same extent, r.nd of the soiuc form as the part which has been n- 
moved. 



CHAPTER XIV. 
OF TUB SEBVOUS SYSTE3L 

DivMMf y Me AWvon* Sjirttm.—CenbrthipmaimJ Sympathetic.— Fibrma tmd Vuieabr. 

Stnetun aaJ Fmu-tiou ^iVerrc Fibre*. — OaUry»lai and Omtri/mflit.—Rat* t^ CWAKfiifijL 

Anaiamcal ExtUKtaatioH qflh* Stmettm and FuHttiona o/Xffvt VttieJtt, — TTtfjf Sffvm Itf^ 
moH, an Maifasiftea of' Farrf. — Kirmmt of Time imtTothirrd hy Rt^ttarmj UanyHa, — Oaik- 
tiom necemurj to A'crre Avtinty. — SertMity of ftfjMtir nod lUst. — EiKtrirai JCramiamUm tf 
ikt f\metions of Veticif*, — Ani/omicai imd Elnrtricttl KsiumaatumM aym. 

Atdomatie A'ctm Arc — OttkUedSem Atv. — Uuliiftk Are*. — Qommitmtt. — Ragiattrwj Sir* 
ArtB. — Sauortum. — ft\ftmeHtiat A re 

SuffyextioHx deruxdjivm certbral Htnuiar^ rz^ttrtintj the SinJ. — /** iadependait Siiitemct vd 
Itiuuortalitjf. 

JdtOM of 1^ine ant] S/vw. — Ofijtrtiiyf m^jertirt^ and iitipersonal Operatiom». — VetOiifea ^1»- 
jtrtMxioiu and Uictr litirrprttatiun. — / uttfe !^at%rt of Kitoticd</c. — Menttd Fmotiam*. 

The ports and functions which have been thtis far described stand in 
Imporuixw of *^^"J"i"^'on to the important system on the study of wbidi 
thoocrroM WO now enti^r. It may be truly said that the position of any 
^f***"^ animal in the scale of life is directly dependent on the de- 

gree of development of its nervous system. Tlirough this it is brouglit 
in relation with the external world, deriving sensations or impressioiu 
tlicrcfrom ; through this, also, all voluntary niuscolftr contraction takes 
place. Whatever the grade of intelligence tnay be, the degree of dei-el- 
opment or expansion of tiie nervous system is in close correspondcDOC 
thereto, from the lowest conditions in which it is first making its a]^icaff- 
anoe in tribes which are scarcely distinguishable from vegetable forms, 
u]) to its highest elaboration in the ccrebro-spinal system of man. 

The physiologist has to confess lliat in this, which is, without doubt, 
Imiwrfrct wm- ^^^ ""^^' imi)ortant part of his science, the amount of what is 
dilion of iho kno\Tn with exactness is limited : indeed, so great an obscu- 
mi iject. j^jy. Tcsi» upon the functions of tl»c nervous system tliat he 

has to content himself rather with the description of structure than offer 



DmaiONS OF TlIE NERVOUS SYSTEM. 259 

Oie explanation of action. Yet even now a few leading facts have been 
ildpimine'l, which foreslmtlow llie attitude in which the whole subject 
will stand when it comes to be better understood. Among tbeae may 
lennmbcrcd the localization of special functions in special parts of the 
ncrrous centres, as was obaervcd by Gall ; the double office of the spinal 
nffves, lirst rccognize<l bj* Bell, tJiat tlieir anterior roots arc motor and 
posterior senson* ; the conversion of impressions made at the periphery 
iato motions, reflex action, as it lias been termed, 6rst clearly recognized 
lyUall ; the relation of the ganglia at the base of tlie brain to the cero- 
bnm and the spinal cord, as shown by Car|)cnter; and particularly the 
condition on wliich the activity of the entire system depends, 
it nndergoea oxidation or waste, and, among other products, gives 
origin to salts of phosphoric acid. 

For the sake of convenicneo of description, tho nervous system is usu- 
iflr irganlcd as consisting of two portions, the cercbro-spi- division of tho 
]ul and symj5Bthctic. The former is composed of the spi- iitrTou»»y»iem 
pul cord, the brain, tho nerves proceeding from them, and ,pinai «n'i 
leir ganglia; the sj-mpalhrtic is composed of a series of "ympsOicUc 

igliA, nnited by intercommunicating threads on each aide of the ver- 
thnd column, and supplying brandies to the coats of the blood-vessels 
ad viscera of the great cavities. Both portions contain two kinds of 
tructure, n fibrous and a vesicular. The latter is found in „, , 

' fliiroQjt and 

vahoos sittintions; the former serves to connect those mass- vci.icttinr^tni«- 
ea with one another, or to fiirnisfh means of communication *"*' 
firom point to point ; the office of the ganglia, or nervous centres, is for 
l[»c reception of impressions and tho origination of motions. In the 
brain the impressions of external circumstances are, as it were, registered, 
and from it originate the processes of intellection. 

The study of this portion of the mcchimism of man brings us therefore 
in cotitact with metaphysical science, and some of its funda- ^ . . 
mental dogmas we have to consider. Nearly all philoso- inci«(.hyitica 
piicrs who have cultivated, in recent limes, that branch of i'"*^**<'f'''J'- 
knowledge, have viewed with apprehension tho rapid advances of physi- 
ology, foreseeing that it would attempt the final solntion of problems 
which liavo exercised the ingenuity of the last twenty centuries, fu 
thia thoy arc not mistaken. Certainly it is desirable that some new 

•':od should be introdnced, which may give point and precision to 
itTcr metaphysical truths exist, and enable ua to distinguish, scpa- 
ntc, and dismiss what are only vain and empty speculations. 

So Ikr from philosojdiy being a forbidden domain to the physiologist, 
it may be owcrted that the time has now come when no one is entitled 
to express an opinion in philosophy, except he has first studied physiol- 
ogy. It liaa hiihcrfo been to the detriment of truth that these processes 




260 



RELATIONS OF rHTSIOLOOT TO METArilTSICS. 



of positive investigation have been repudiated. If from the constniclion 
of liic Iiuman hrain wc may demonstrate the existence of a soul, i^ noi 
that a gtiin? for there ore many who arc open to arguments of Ibis 
class, on wliom speculative reasoning or a incrc dictum fall without any 
wciglit. y^hy should wo cast aside the solid facts prcsontcd to Vi by 
niBtciial objects t In his communications tlirooghout the universe willi 
us, God ever materializes. lie equally speaks to us through the thoti' 
sands of graecftU organic forms which are scattered in profusion ovcrtiie 
surface of the earth, and tlirough the motions and appearances prescotol 
by the celestial orbs. Our noblest and clearest conceptions of his attri- 
butes liave been obtained from these material things. I am pcnmaileil 
that the only possible route to truth in mental philosophy is througli a 
study of llie nervous mechanism. The cxpericnco of 2500 years, and 
the writings of the great molnpliysical intellects, attest with a inelandwlr 
cmpliusis tltti vanity of all other means. 

Whato^xr may bo said by sixjculative philosophers to the contmr, 
tlic advancement of metaphysics is llirongh tlie study of physiologT. 
AVhnt sort of a science would optics Imvc been among men who had p4ir- 
posely put out their own eyes ? What would have been the progress ol* 
astronomy among those who disdained to look at tlie heavens t Yet tliAt 
is the pa'postcrous course wluch has been followed by the so-called pliJ- 
losophers. They liavo given us imposing doctrines of the nature md 
attributes of itie mind, in absolute ignoranco of its material substratum. 
Of the great authors who iiavc thus succeeded one another in epheroaal 
celebrity, how many made themselves acquainted with the structure of 
liie human brain ? Doubtless some had been so unfortunate as never to 
sec one ! yet that wonderful organ was the basis of all their specolatioxis. 
In voluntarily isolating themselves from every solid fact which miglit 
8cr%'C to be a landmark to them, they may be truly said to ha^-e sailed 
upon a shoreless sea from which tlio fog never lifts. The only (ad whidi 
they (each ua with certainty is that they know nothing with certainty. 
It is the inherent difliculty of tlicir method that it must lead to unsub- 
stantial results. What is not founded on a material substratum is nce- 
cssarily a castle in the air. 

Returning now to the general description of tho nervous mechanism, 
and following the division above indicated, wc shall consider, firet, the 
fibrous clement of tlic nenous system, and, second, the vehicular. 

First. Of the fibrous there are two varieties, one belonging to tlie 
Kihruus or tn- cercbro-spiual, and the other lo tlie sympathetic. The for- 
tuiar pariiun. mcr may be described us a delicate membranous tube contain- 
ing a semi-fluid material, and presenting under the microscope a pellucid 
glaasy appearance when examined in the recent state ; a spontaneous 
^paration or partition, liowevcr, soon cnsucd, a white matmai or mcdul- 



d 



KEK\X FIBHES OR TCBES. 



2C1 



[ la appearing inimcdialcly witliin tiic nicmbranous tul)C, and affording a 
Dlrast 10 the portions which arc toward the t:<:ntre or axis. In tliia 
ate the ncne-tube presents tlie appearance ot* parallel lines toward its 
pcjipheT)-, the outer one corresponding to the membranous Jtftnt.mnr, 
sheath, and the inner to the internal limit of the coamJalcd *'■''"''"'"""'« 

^? pf Sclin-Atiii, 

material. In this condition thu tube is very prone to as- axU lyiimkr. 
gumc a beaded appearance, cither by the influence of pressure, or even 
spontaneously. Names have been given to distinguish these parts from 
each other ; the central grayish portion is called the axis cylinder or axis 
band, bincc it may be of a flattened sliajH! ; and the material which sur- 
roonda it, intervening lx>t\veen it and the raernbrannus investment, is des- 
ignated the medulla or white substonce of Schwann. Tlierc am be no 
doubt that the membranous tube, tlic white substance, and the axis cyl- 
inder discharge ditTcrcnt physiological functions. In clicmical composi- 
tion they also diifcr : tlie tube li a nitrogenized structure, the while sub- 
stance oleaginous, and the axis cylijider is supposed to be nitrogenized 
also. In the first development, the axis cylinder is first formed, and the 
white substance then cast round it. 

Ifaportion of ancrve, a, /Vj/. 114, be placed 
in concentrated accttc acid,tho axis cylintleis of 
its included tubes will, in the course of a day 
Ajri.eriiiid« of B«vi£ or two, be seen protruding in a brush-like fonn, 
as at bi the effect being very well shown when the nerve is sufTiciently 
slender to bo subsequently examined by the microscope. 

The nerve fibres ran in a direct course to their point of distribution* 
Of their manner of tennination we shall s]}eak subseijuenlly ; T^.„nj„„j 
here, however, it m:»y be remarked, that occasionally they ex- brnnchiniet of 
hibit preparatory terminal branchings, as shown in /^/y. 11^, °*"* "*'" 
p. 262, observed by KoUikcr in the case of the frog: a, a being bifurca- 
tions, ff a trifnrcation of a small ttvig from tlic cutaneous thornric muscle. 
Similar sulxlivisionsofthe ultimate ramifications have been noticed in the 
amphioxus, fishes, insects, and it is certain that they also occur in man. 
The slieath of the nerve fibres is an clastic membrane, which is nei- 
ther acted on by dilute alkalies nor by boiling, but is solu- riiwnicai rwo- 
ble in concentrated .icetic acid and strong solutions of pot- ™woriicrTo 
ash and soda. By nitric acid it is stained yellow, and, though ubru. 
not identical with clastic tissue, has a certain resemblance thereto, ap- 
proaching, however, more neju-ly to a protein substance. The axb eyl* 
indcr is, as is shown by its behavior ivith reagents, a protein substance, 
differing, howevcT, from syntonin and also from blood fibrin. From tlio 
latter substance it is distinguished both by the difficulty with which it 
dissolves in acetic acid and in a solution of nitre, &om the former by ita 
insolubihty in hydrochloric acid. 



262 



KZSVZ F1BBE8 OS TL'Bi:& 



Sobdlrlitoa af Mm fibiw In tb* ttng, raacntAtid S5a dUwtitfc 

Of such fibres, aiTjinged parallel to each other in bundle*, the bnn^ 
imilctl by fibro-celhilar tissue, nerves arc coni[K>scd, the tissue not only 
Bccouiplishing that mechanical object, but also affording a nidus for blood- 
vessels, whicli run in a courBe parallel to the ncr^'C fibres. Though vc 
Fom nn'l tht have Bpoken of those Hbres as cylinders, they, in reality, oj>- 
ofniirvB ribnj*. proach more nearly to the tigm-e of acute cones, since, thot^b 

their diameter is from the i^iVt ''^ *'*° ToUTi °^ *" "'*^^* ^" ^^^ tieive 
trunks, they diminish to ihe-j-j^y^or the-j^^J^^of an inch as tboy readi 
the nerve centres, and, in tlie same maimer, their diameter becomes less 
4s they branch off in their jieriphcral distribution. In tho bruin, as they 
pass through the medulhi to the cortical jjart, they e^iibit a similar dim- 
inution. 

The sympathetic fibres differ from the preceding in appearance. Being 
rtmrarfcr of ^* ^ ycllowisU-gray color, and only about lialf as large, they 
».vfiiF>atbotic do not show tlte separnlion into an axis cylindcT and white 
»'!'"'*- investment after death, as is tlje case with ccrcbro- spinal 

fibres ; they may therefore bo regarded as being more homogeneous in 
tlieir construction, or possessing a constitution like that of tlm other kind 
of fibres when they undergo diminution ajid approach their central or 
pcripheml termination. Kvcn in the Lcrebro- spinal fibres the quantity 
of white substance present is very variable ; the retina, the olfactory or- 
gan, and the Pacinian corjmscles furnish instances of its absence The 
sympathetic, gray, or gelatinous fibres, as they are indifibrently calledt 
contain numy nucleated eorpusclcsT which may be rendered very distinct 
by the action of acetic acid. 



1 




KEn^'E TESICLES. 



263 



Ncrv-c fibres terminate in various ways. Their ends may thin out and 
become free, or they may forra a loop, and so return back in jj^^^^^ ^f 
tbe'u* Gourirc. Kaclk nerve runs in an unbroken line iirom its unnititttiun of 
origin to its tcnnination, but bctwceu tlic adjacent ones in- ""''''''^• 
Icrcommunication is established by the formal ion of plexuses. On the 
otiicr haiul, aa tlic fibres arc preparing to cuter the nervous centres, the 
membranous tube dibtes so aa to receive a nerve veside, jj^o,^, ^f n- 
with wliieh the diaphanous axis cylinder i.-* thus brought in «rptionofv«i- 
contnct. Where corpuscles arc received into the moniljran- "*"' 
oos shealb, it is not always certain but that tlie fibre lias some other 
termination beyond. Some have supposed that Heiialtive fibres differ 
from tlic motor ones in tho circumstance that the former alone ore 
brought ia connection with tho corpuscle*, but this is vcjy unlikely. 

Second. The vesicular nervous substance is composed of nucleated 
cells containing a granular substance, with which there are The vraicuUr 
intermixed, cspecialJy near the nuclei, pigment granules. ro'Ucn- 
These graniUes, however, are souietimcs absent, as in the vertcbrata. 
The nucleus of each ganglionic vt'sicle often presents a nucleolus; the 
diameter of the vesicle varies from yj^j to -yf^ ***' '^ inch. These veSr- 
icks arc found m the ncn'O centres, llicir coloring mutcrial communicat- 
ing to tliose parts the peculiar tint thuy display. In 6ha|je tliey vary 
very mucli, some being spherical, some ovoid, and others caudate, ex- 
hibiting processes which arc filled witli granules, or which, becoming 
eventually transparent, communicate with simitar processes from other 
ceUs, or are continuous with the axis cylinders of the nerve-tubes. Ac- 
cording to Axniunn, the axis cylinder is a continualiou of the nucleus 
of the cell. Tlie ganglion vesicles, as they arc termed, are character- 
ized by containing Ji largi! amount of pliosphor- 
ized oil, and it is probable that tlio oxidation of 
this material is a condition of their functional ac- 
tivity. 

/''iff, 116, ganglion globules (nci-\'e-ccll3), from 
the Gasscrian ganglion of the cat. I. Cell, with 
short pale ]>rocess, showing the origin of a Kbre; 
a, sheath of the cell and ncrve-tul)C, containing nu- 
clei ; i, cell membrane of the nerve-cell. 2. Cell, 
^^-t ^ with tho origin of a tibre without ahcath ; i, cell 

^^K jy^ membrane of the nerve-cell. 3. Nerve-eell, de- 

^^K /f privtrd, in tlic preparation of it, of its membrane 

^^R«<di^.p.tB,ariMji. and external sheath. (KolUker.) 
■ .mcun. jTi^ j|7^ p i264, bipohir nerve-cell of the pike, 

conlimicd at each end into ncne-tubes. a, sheath of the ncrvc-ccll; If, 
flhcatli of the nerve ; f, medulla ; d, axis cylinder continuous with the 



Fig. no. 
.1 




k 



UulUpoUr mrrt^iaii. ma^tAifd SOO dUtMt«r«. 

Tliesc probably are continuous ivitli the axis cylin- 
ders of the nerves, in connection with tlic veside. 
Fig. \ 19, tubules and ncn-o-cells : A, from srmpi- 
thetic ganglion; *, a sept- 
rate cell, showing its pellu- 
cid nuclem* and nuchH>lus: 
B, from the gray substance 
of human cerebellum: ^,4, 
plexus of primitive fibres; 
r, nucleated globules; •. 
a separate cell from ho- 
rn in ganglion of Gasser. 
(Wagner.) 

Fig. 120, tubniefl azid 
nerve-cells of human brain : A, 
nerre-celifl lying in the midst 
of varicose nen^e - tubes and 
blood-vessels in tho substance 
of the optic thalamus: o, ^ob- 
ulc more enlarged ; i, small ^'a»- 
cular trunk: B, B, multipolar 
ncrve-ccllfl from ihc dark, -j-wr- 
tion of the crus cerebri. (I'ur- 
kinjc) 

Such being the constmction 
of the fibrous and vesicular ma- 
terial, wo may next inquire into 
tJieir functions. 




Hmnui Dnrc tsbuks nut «U* 



CENTRIPETAL AND CKNTRIFPiaAL FtDRES. 



FUNCTIOKS OF NER\'E FIBRES. 

That the function of norvc-tubca is fo conduct impressions, is proved 
IT many different fiicts. On pulling a ligature round a nerve, lunciiotis of 
r cutting it across, it no longer transmits the usual influ- *'"'•'' ^i"^* 
Bnces. A more criticiil examination sliows that impressions mado on 
!ic external extremities of a ncn'c arc conveyed by it to the ccnlrcs, 
ind the influences originating in the ner\'0U8 centres arc conducted along 
inch trunks to the parts to which they are distributed. This double 
iatr therefore implies that there arc two classes of tubes, the centripetal 
bid rentTifugal, though thus far no structural diflercncc between them 
tas lM?cn detected. 'I'licy can not of thcmsctves either originate imprcs- 
none or motions, these in every instance arising from external or central 
^cncy. The centrifugal libre-s, wljen cut across, may show „ m .. i 
90 effect if the part still remaining attached to the nerve cen- auti ccniriru* 
re is irritated ; bnt if the other part connected with the pc- ® "'' 
tJphciy be pressed upon or pinclicd, muscular contraction, that is, mo- 
tion, residts. If centripetal tibres be examined in like manner, the part 
BOQiuected with the periphery being irritated, no result arises ; but if 
he part connected witli the centre be irritated, sensations, general or 
^lecial. as the case may be, are perceived. These several ctlccts ensue 
Irben the motor or sensory nen'O is intact; for, on irritating llic one or 

k4>thcr, motion or sensation, as the case may be, is produced. If the 
lie trunk of a ccntri{)ctal nerve be irritated, the mind ret'crs the sen- 
sation to all those parts to which the branches of that nen-e are distrib- 
uted; if a part only, then tlie sensation is limited to those portions to 
Rrliicb the librils of lliat part go : but, besides this, the mind also recog- 
tuzes the j»artienlar spot upon the trunk to which t!ic irritation has boon 
ipplio<l. In like manner, wlien the entire trunk of a centrifugal ner>'e is 
rrit«led, all the muscles which it pdpplics contract; or, if only a part, 
hen those muscles which are supplied from that part. From tlic ana- 
Dmical fact that a nerve-tube does not anastomose with its neighbors, 
be xnflnenccs which it conveys arc transmitted along it without any lat- 
tnil diffusion, and every fibre discharges one duty, and one trni(roff„nc_ 
llone. The centripctral can never assume the function of tion intdo 
ho centrifugal ; and in the case of ncnc3 of special sense, 
hats is the same restriction : (he optic ncr\c can not transmit the im- 
irCABionB of sounds, nor tlic auditor}' the vibrations of light; the nerves 
rf cotnmon sensation arc affwted neither by one or tlio other, but they 
irc by variations of temperature. The velocity with which ^^^^ t^poo- 
Itcee intlucncca pass along ncr^'o tibres is indefinitely Ivus iiuciiuiuj la 
fbjin tliat with wliicli electricity moves in a metal conductor. '"='^"- 
Xbus lar, however, no sati^ilactory measure ol' it has been obtained* 



26G AXAXXKIT OF KEETES AND ELECTBIC OOKDLCTOBS. 

The pjcpcfiments of Ilplralioltz pivr, for tlic rate of propagation, from 53 
to 88 fcot per second in tlic frog, nnd in man 200 feet, the velocity rii- 
ing with the mean animal iieat. At one time it was thought thattbcrc 
arc perceptible lUfferences in tliia rate in the sanio nerve of different indi- 
vidools, or in ditU-rent nerves in the same individual, IjuC these cooclth 
siona arc admitted 1o be erroneous^ or to be e:!Cplained upon another piia- 
ciplc. It enn not be denied that tlicrc is a genend resemblance betwwn 
the manner in uhicli a nervous fibril transmits its influences and that in 
which a conducting medium convcjs an electric corrcnt, though tlic vc- 
RMflnbUnoo locity may be very dificpent. There 13 a rcsemblant-c bc- 
tNtwecntbs twecn the arrangement of the axis cylinder surrounded by 
tridi conduct- i^ white substance and mcmUrauous tube, and that of a met- 
^*^ alline wire wrapped round with eilk, or other uon-conduct- 

iug material in many electrical arrangements. An electric current arti- 
ticially transmitted idong a nerve trunk will, as the nature of that tmnJ: 
may bt*, give ri.se to muscular contraction, or produce general or special 
sensation-s or originate retlcx action. For these reasons, it has long bom 
supposed, by many physiologists, that the influence which posses along 
nervous (ibros m analugous to electricity, if it be not idcnticd thexewith; 
but all atlcuipts to prove the existence of an electric current, either in tlic 
centrijictal or centrifugal fibres, have thus far been aljortive. It niay, 
however, lie remarked, that the argiTmcnts which are commonly present- 
ed against tlic hypothesis of the identity of the nervous agent and eloe- 
Iricity are but of little weight when critically csantineU. Thus it is said 
that an electric current, passing along a ner\*c fibre, spreads laterally, 
whereas the nervous agent never does ; but this is all de]x-ndent upon 
that (jualily formerly known among elcctriciiuia as intensity. There is 
no reason to suppose that a thermo-electric current, the intensity of wliicU 
is very low, would exliibit such a lateral propagation ; whereas a voltaic 
current, whose intensity is high, does it without ditHculty. Moreover, 
though it has been stated that the electric conductibility of a norvoos 
trunk is indefinitely worse tlian that of a metal, even lower than tlmt of 
ft bundle of muscular fibre, it sliould be remembered in tliesc discussions 
that the conducting i>ower is in the axis cylinder, and no attempt has 
ever yet been made hy any experimenter to isohite that structure and sub- 
mit it to proper examination. It is just tlie same as though we should 
take a bundle of copper wires, each one of which is separated iVora its 
neighbors by a layer of non-conducting fat ; that we should cut out a boc- 
tion of sudi a construction with n pair of scissors, and then attempt to 
determine its conductibility. That, under any circumstances, would be 
low enough ; and tlic cliances arc that the non-conducting material would 
be smenTcd over the ends in the act of making the section, and the speci- 
men refuse to conduct at all. In a similar manner, we may disclose 




:ofJ 




OF NEBVB-CELLg. 



267 



^»II tiio8C experiments which have been brouglit to prove the dissiinilari- 
ny of clcctricii/ and the nervous agei)t, by iiiten-oniug u piece ot' metal 
IlKtwecn a section of a ncnoiu trunk, it imviiig been ibuud that under 
sucli circumstances llie nervous iiiHuence docs not pass. 

The physical condition upon whicli the activity ot' tlic nervous moch- 
anism <kpends is the supply of arterial blood j for, although jj^p,,,^, ^,j,. 
tlic nerve fibreg never receive or are penetrated by blood cap- iiy dt|«nd< tm 
iilaries, tliesc latter run iu company with them in the ncr\-- "*"" "*"' 
oufl iasciculL It would ajjpcort however, that the supply of arterial blood 
ia of far leas moment in the function of tho nerve fibres tlian it is in lliat 
of the nerve centres. Tlu3 is shown by the limited supply given to the 
fonner, and tho abundant one to the latter ; by tlto comparative eSect of 
a stoppage of tho blood circulation, in which case the action of the ncrvo 
centres is instantly arrested, whereas that of the fibres may continue for 
a long time. On tho whule, there arc strong reasons for believing tliut 
tite conduct ibiiity of the ncrVc fibres is as purely physical as is that of a 
metal wire, and that the supply of blood that they receive is only for tho 
purpose of maintaining llieir construction in u |H:rtcct state. 

We have stated tliat there are nerves the functions of which arc essen- 
tiaUy difi'orcnt, such as tho centripetal or sensory, and the j.ipntifl,afifln 
eentrifugal or motor. The identification of the class to i>r Um dus of 
Srhich a nerve under examination belongs, may aomctimea 
be Uiade by examining its manner of di. tribution, or its ganglionic con- 
liection; sometimes by experiment, by making a section and irritating 
the cut extremities. In these cases, however, caution has to be cxcr- 
IBaed in comuig to a conclusion. 

rrNCTIONS OF NERVE-CELLS. 

The ncr\-ous fibres having for their duly the conduction of oxtenml 
apressions and the transmission of nervous iniluenccs, the FancUon «f 
Fi9.m. ner\-c-cells or wrvvwlciM, 

vesicles are for the re- 
ception of those impres- 
sions and the origination 
of those influences. Tlie 
nerve centres or gnnghla 
are mad© up of vejiiclcs, 
granules, and iierve-txibes 
*i conjointly. 

}^i^, 121, dorsal gan- 
glion of the sympathetic 
nerve of a mouse, o, *, 
cords of counectii^n with 




2G8 



VI3ICLES ACE MAUAZIXES OF FOfiCS. 



adjacent ganglia ; c» c, o, r, branches to the viscera and spinal ncrvca ; df 
nen'C-opUs; f, ncrve-tubcs traversing the ganglion, (VaJentin.) 

For tJie explanation of tlio function ot'thc nervo centres^ it u eescnlial- 
ninrtioa of ly noccssary tliat we should have clear views of the functioQ 
ii!i7Ki)uaul'!l o*^'l»c ncn'e vcsicla«. It Ims appeared to mc tliat their Jatjr 
inMHy. lA manifcRled by I heir anatomical relations. The intlactkoc 

whatever it may be, wlncli passes along a nor\'oiis cord, is completdy 
isoL'ited therein, »nd never lojivcs the fibril in which it is passing froin 
its origin to its teruiination. It is isolated by the white substance of 
Tlw-r {irnnlt Schwann, tint it is very plain, as a tliousand phonomcu 
r^ai'^riiiir "* ^^ ^^^^ ncn*ou5 system prove, that there are places of escape 
new cbonovis. for thts influence, although it may be confined in the nerro- 
tube, and these places can be no other tlian the vesicles. Their caudste 
aitpect, or niulti]>olar form, as it is often termed, will bear no other inler^ 
prctation. Tlie disturbing influence coming along the axis cylinder of » 
ncrvc-tubc, finds itself delivered into the gra'nuhir material in the interior 
of a vesicle, a material physically continuous, in the opinion of many 
physiologists, with the structure of tlio axis cylinder. Through Has 
granular materi^d the influence is transmitted, and if the vesicle shoold 
have on its distant contour two or more ncrvc-tnbcs connected wHh it, 
it would Bcrm to be the necessary result of such a state of things that 
tlic influence will pass down all those channels. For these reasons I re- 
gard the nerve vesicles as being ooustructions for tJie ptir{)osc of opening 
out t!ie closed nen'e tubules, and penuitting them to deliver tlicir energy 
into new tracts. 

But more than this. Whatever may be the manner in which the 
DiiTunioTionn. nervous influence is propagated, or conducted from point 
"SJ^mlu' ^° P*^'"* ^^ ^^^^ granular material within tho vesicle, there 
rial. must he now, since there is no structure to prevent it, a lat- 

eral spreading of cilcct. It is not to be suppose<l that the jiassago is 
made in a direct line, iVom the terminus of tho centripetal to tho origin 
of tlie centrifugal fibre, across these caudate vesicles, and restrictctl there- 
to. There is no isolator to confine it in any such track, and it seems to 
follow of necessity that tlie whole contents of the vesicle must be affcct- 
VerioicA-reuin ed, and this irrespective of its magnitude. Such a condition 
■ndTre maga- *^^ *l"i"g8 introduces the suspicion of a second great duty 
zjnraorrorM. which the vesicles may diseliarge in retaining within them- 
selves, at all events for n short jwriod, the influences that have thus es- 
caped laterally, and thus they become temj>orary magazines of power. 
rniiMiUr, 1.1- •'^"^ perhaps tins may bo the true interpretation of the action 
polar, miiiii|x>. of Unipolar and bipolar vesicles; the unipolar bciui; a capsulo 
tor tho collection ami con8cr^•atlon ol the entire dchvercd m- 
flucnce, tho bipolar to admit of the passage onward of a large portion of 





RETEirnOX AXD INTERFKRENCE OP IMrRESSIOXS. 2G0 

fbe force, but by lateral diffuaion (o preserve or delay a part, and the 
muhipoliir at oucc ])cmiiiting ot* conservation and of & dischaigo into, 
{)erlia|)s, a multitadc of nv-vr elianneln. 

Upon the SQtnc principle that multicaudate vesicles permit of the gs- 
ttfo of ncr\'ous influence from the sin-jjlc clianncl in wbicli it intcrfcrwiceof 
iiSS liecn coming into many new ways, so likewise they ifflprcMiona. 
most bo Uie scats of the intcrterence of influences delivered into them 
&om many centripetal fibres at the same time. Thus we may imagine 
a trientidatc vesicle into the granular material of whieii an inflacncc is 
delivered simultaneously by two ccntrijwtal BbriU, and these, reacting on 
one another in tlio interior of the vesicle, give rise to a resultant which 
may ditTcr tVoni them lioth, and this is passed on tlirougli the third, the 
ccntrifugnl fibril. 

Regarded in this way, the function of a nerve vesicle may therefore be 
stated to be, Ist To permit the escape of an entering intluencc out of the 
■oUtary channel in wliich it has been isolated into any number of diverg- 
ing tracts; 2d. To combine influences whicli arc entering it from various 
directions into a common or new rci^ulc ; 3d. By permitting of lateral dif- 
fiuioa to take olT and keep in store for a certain duration a part of the 
'passing influence 

Our attention can not fail to be arrested by this last eflect ; for if ihcra 
be a propcrtv which is characteristic of the nervous mechan- „ 

r r J .11 ..... noirntion oT 

isro in tts utmost degree ol development, it is this of retain- tb« rcNtign oT 
iog the relics or traces ot' impressions which have formerly *'"!'"*"*"* 
been nado upon it. As it goes on increasing in ])erplcxity as we rise 
thnragfa the animal series, the provision for the retention of sucli imprca- 
ftiona becomes more and more strikingly marked. Ganglionic mnsscs, 
which, from their [Ktsitiun and structure, are marked out for tliis duty, 
appear in that ascending scale in increasing magnitude. To those we 
may aptly apply the designation of registering ganglia, since ){(»:^^t«r]nK 
ihcy truly store up the traces of ancient impressions and keep fi»"«l'»* 
them in resen*c These ganglia must, moreover, be the scenes of the in- 
Icnction and interference of the impressions they tlms contain. 

The irgistering ganglia tlius introduce the element of time into tho ao- 
tkrti of the nervous mechanism. The impression which in,r^„,(Q„ 
without them would have fortliwlth ended in action is dc- ofthcclcauit 
layod for a season, nay, ]>erhaps even as long, though it may " ""'*' 
!» in a declining way, as the structure itself endures; and with tlie in- 
troduction of tliis condition of duration come all those im])orlant effects 
which ensue from the various action of many received imprest>tuns, old 
mad new. upon one another. 

This internal origination of new results llirough the interaction of im- 
prcsaioua retained in the re^stering ganglia is too important a phcnom- 



J 




VAniABIX EFTECTS FBOM im'AmABLE CAfSESL 

cnnn to b<* jias^d liplitly l>y, mniti especially when vrc consider thr 5ll^ 
prising results to wliich it cvcnhxally leads in the Iiiglicr foims of lilc. 1 
lUu>tntioD of shnll therefore, witliout nny npology, digress briefly for the 
the pruciufiiirti sakc of illustratltifr iiiv mcnninj;, bv ehowinc: how, even in 

of varijilJ* r*^ , . , , ,"^ ' .■.,-, ^ , * 

tului'.rinvui- Ihc niatcnnl world, from conditions which areas fixed as fftlc, 
•bla »UM>L through interaction of consequences variable results arise. 

The laws of nature, being founded on pure reason, are absolutely tin- 
changeable. Of the things which arc presented to oar contemplation, 
they alone arc invariable. Material substances of oxry kind wear Iff 
time, and exhibit incessant alterations, and this the same whether tliev 
are of a tcrrcslrial or a celestial kind. There arc tides* eclipses, seasoiu, 
births, deaths. Throughout llic universe then* is no monument lliot re- 
tains its primordial condition ; for all material aggregaliona arc only 
forms, and every form, in the process of time, must perish. There ait 
changes of the surface of the earth, change in its position as to the stin, 
changes in the places of systems of worlds as to one another. E\'eiy 
thing is at every moment in motion ; but in the midst of nil, every law 
of nature, as, for example, the law of gravitation, endures without ■\"aria- 
tion for an instant, and is never for an instant suspended. 

This invarialiillty of natural laws from ngc to age, even under einmm- 
stancos in whic!i we might suspect a change, is illustrated by the parallel 
which may be traced between the development of the most x«cent cm- 
hryos, as of man, nnd those of the ancient geological times, or botu*«ai 
liuman development and that of the wliole animal series. In all tlicse 
eases such a phenomenon is never witnessed as that of a part springing 
from notliing : it comes out of something existing before, and exists as a 
conscr|ucuce of some preceding act. The order in whidi part arises from 
part is the same norr as it lias been in all times — the same in organ- 
isms which arc most distinct from each other in stnicture or position la 
the natural scale ; nnd thu.? we sec that development is not only the con- 
sequence of law, but of law which is unchangciblc and univcrAil in its 
application. 

As with tliesc ]>henomona of development and nil luitural facts, so mth 
the operations of the mind. There is no such thing as a spontaneous or 
self-originating thonglit. Kvery intellectual act is the consequence of 
some preceding act. It comes into existence in virtue of something that 
has gone before. Two roinda constituted precisely alike, and placed 
under the influence of precisely the same external physical circumstances, 
must give birth to precisely the same thought. Such is plainly tlie 
consequence of that invariability and universality of the laws of nature 
on which I luivc been insisting, which is ilhi.^trated by the fact wc so often 
witness in our daily affairs, and strikingly in the case of philosopliical 
di.icovej-ies, the same idea occurring to many persons at the same time. 



J 



I 



I 



I 

I 



REOISTTERINO aANOLIOX. ^ 271 

U thU Bamencds of action to wliicli wc allude in that popular exprcs- 
400, common aenec — a term full of meaning. In the ori^jinalion of a 
ighl there are two distiiiet conditions involved — the stale of the mind 
dependent on antecedent impressions, and the existing physical ciiv 
iccs. The brain is the instrument on which external circum- 
slaocea play; but in the same manner that the course of time presents 
Utf with uatural vicissitudes, such as night and day, tlic seasons, the tides, 
spring and neap, with their ebb and flow, variations of events may ensue, 
rH>twitlistan<ling the fatc-likc aspect of the acting law, and this tliroiigli 
the interaction of consequences. So tlic earth revolves round the sun 
05 a consequence of gravity, and for the same reason docs the moon re- 
volve round tlio earth ; for the same causo do the tidc^ flow and ebb in 
the sea ; yet there will be spring tides when the sun and moon draw in 
one direction, and neap tides wlion tlicy dmw in opposite ways. Out of 
the invariable tlic variable may therefore arise* 

To return from this digression to the phenomena displayed by regis- 
tering gan;;lia, tn continuation of the views offered, I may ])r(v Min«tmiion of 

sent as an i'.xample the; manner in which I .slioiild \k disnose<l "i^^lf""^*? 

» . . / tf*"!!"* I'l In- 

to regard in this rcs|NM:t the entire nervous system of the ar- ttci». 

ticolata. Constructed as tlicsc animals are upon an axis, the nen'es 
which are given ofif from the ganglia npon that axis right and left, a |)air 
for eftdh segment, arc primarily purely automatic, and act therefore pri- 
marily in a purely reflex way ; an impression made on the peripheral cx- 
tnsmity of one of their centri|>ctal libres is conducted to the ganglion, 
passes through it, escapes along the centrifugal fibre, and a motion oe- 
ctirs. But the whole iiitluencc is not thus promptly disposed of, A ])art 
of it is conducted by commissural strands to the copltalic ganglia, and 
there held in reserve. And the same thing holds good for cv- v ,■ r 
cry one of the ganglia of the ventral cord, so that for them all iiit wpWic 
tiie cephalic become a i»oint of common convergence, or, in my ^*^^ '*" 
view, the common register for them all. Here, at this focal point, are 
stored up the relics of whatever impressions have been made upon the 
common peripheral ner\*es, and here are received those which are brought 
from the structures of s|>ecial sense— the visual, the auditory, the olfac- 
tory, if any, Thexe does not, then, appear any great difficulty in ex- 
plaining the well-marked deviations from automatism which these ani- 
noftls may present. 

The action of every ganglionic mechanism depends upon the existence 
of certain physical conditions, among which, as being of par- NVrvc eontn* 
ainoant imjwrtance, one may Ik: discerned. It is the due ccpi by oxiJ*. 
supply of arterialized blood. If this be stopped but for a ^^'°^ 
moment, the ner\c mechanism loses its power, or if dimim'shed, the dis- 
pby of its characteristic phenomena correspondingly declines- If, oo 



k 



272 WASTE AND HEPAIB OF MEBTOUS HATTER, 

the contrary, flic supply Vc unduly great, or its oxidizinj? power arti6cUl> 
ly increased, there is a more energotic action. TUis latter condiiiou of 
things is presented in the earlier stages of tlie rcspintion of protOAidttof 
nitrogCD, an increased niusoulur )>owcr, and an exaggeration of the pro- 
cesses of intellection. The opposite state ia witnessed ivhcn carbonic 
acid, rnorc or less dilute, is breathed, from that hlunting of the iutcllectoil 
faculties mid indis[H>i;ilion fur muscular exertion which is felt in Ut-veft* 
tilated apartments where carbonic acid Is peruiittcd to accumulate, to ik 
profound torpor ond insensibility experienced vhoa it is in a cnon oon* 
centratcd ?tatc. Tlicse exaltations and depressions of the capabilities (rf 
the nervous instrument are. therefore, clearly of a cbcniioai kind, andnuf 
be produced artificially and nt plcasarc by the respiration of appropriale 
gases or the administration of certain drugs. Nay, even the accumuU> 
lions of the effete pro<bicta of the economy arc sulficicut to give ri^c to 
such diminutions of power, as we sec when bile or urea is permitted to 
accumulate in the blood. The therapeutical and toxicological iuflueno^ 
of certain medicaments arc illustrations of these principles. Of sncli 
substances, some act on the sensorial and some on the motor powi:rs. 

The copious distribution of arterial blootl to the nervous centres indi- 
Xc««w{tyoff«. catcs that they undergo a rapid waste. Tliat supply can 
jiair ui>i Kac jjqj bc fof thc mcto purpoae3 of growth alone, since, when 
once maturity is reached, the nervous mechanism presents but little ex- 
pansion. The provision fur nutrition assures us that that action mus*. 
bc rapidly going on ; but the etpnlibrium of the system betrays that such 
nutrition is not for development, but for tlio repair of ^vaste; and, in- 
deed, this waste proceeds at such a rate that there arises in some portions 
of this system a necessity for periodic repose, a time for the restoration 
of the parts. If any ailments were required to establish beyond dis- 
pute tluit snch a disintegration of thc material of thc nerve centres docs 
occur, it woidd l)e furnished by aa examination of the urine ; for, in nerv- 
ous substance, phosphorus occurring as a cliamcteristic ingredient, it 
must give rise to the production of phosphoric aeid, or salts thcrooC in 
pMtniciion of tl»<^ supposed i»criods of actinty. Moreover, in this met*- 
nm-flM rn«to- morphosis of the vesicular structure ammonia must evcnln- 
iHirtiun lu nrr*' ally onsc, froui the cell walls if irom no other source, and 
KUA »u-iivitj-. accordingly we find in tlie urino that churiieteristic doable 
salt, thc phosphate of soda and ammonia. The amount of tliese alkaline 
phosphates has long been known to bc in proportion to the activity of 
tlie nervous system, particularly in thc case of individuals, such as cler- 
gymen, whose mental powers arc tuxcd undtUy at stated intcr>-als. Thc 
general feet that the degree of energy whicli this system exliibits is de- 
]}endent on the activity of respiration in diilcrcnt tribes of life might be 
established from many familiar instances. 



J 




COMPOSITION OF XERVOnS MATTER. 



273 



More precise ideas would lie arriTcil at regarding the waste of the nen*- 
OBS mechaniHin if wc possessed a more accurate knowledge of its chem- 
ical constitution. Tiie cxaiiiinalions liiilierto made are tar „ .., , 
mca agreeing with one auothcr, and iliiH, to a certain extent, oervoua mnui- 
u due Ui tlie difficulty of obtaining the true nen-oua tlsBiic in 
VI isolated state, or unminglcd with other inten'ening structures. The 
tollowing tables will give, however, a general idea of its composition at 
liidcrent |Krriod8 or in ditferent conditions. 

A^ffU of Brain o/Jiffermt Om^ohb ftf lift, {From L'llfrllier.y 



r 


AnfuitlK 


Yonilw 


A4n1t& 


Aarc4. 


IdtoH. 




837.90 


ni.m 


'Sfi.IO 


73A.AO 


70tf.80 


Albmnen 


70.00 


lu-j.oo 


84.00 


86.50 


04.00 


Fii 


»4.fiO 


fiA.OO 


fil.OO 


48.20 


C0.00 


rkRuiuiRc iintl B&lla 


£9.60 


8A.90 


10I.!H> 


IL'1.80 


UBJiO 




P.00 


16.50 


I*l.W 


10.00 


S.&0 




UHW.IM) 


ifHin.w 


10(H>.00 


1000.00 


1000.00 




Cbiiyiomtioa of Spinai Card o/" AAtU. {From VUerilier.) 

Water 710.60 

AlbumCD 78.00 

F« 82.60 

(htnazotai 115.00 

PboKithorui I9.<W 

lOOff.W 

^ ihdnUiiry and OfrtkaJ SvhtUma t^ Brahi ^IiBot. (f)rom IjUMnffM,) 





OmticAl Mid Mrd- 


UoitlasL 


MedulUrr- 


Wmdt , 


T 70.00 

!>4:.oo 

7'?.00 
31.00 
I'O.OO 

1' 11.00 


Sfi0.00 
75.00 
10.00 
37.00 
14.00 

12.00 


790.00 
99.00 

189.00 
<J.0O 
10.00 

13.00 








ExtrmcUro, lactic acid, and mIu... 
I'ka*ii)uii0'4 of lime, magneua, anil 




I0OD.00 


998.00 


1000.00 



From which it would appear that the percentage of water is greatest in 
ho early pcrioils of life, and that of phosphorus in the adult. Attention 
uy aUo )ie drawn to the fact (hat the |)ercentage of phosphorus in the 
in of idiotfl ia verj- low. It also npi)cara that the constitution of the 
rhiie and gray portions of the brain U dill'crcnt, as might have been an- 
ipated from tlu^ir appearance^ the color of tlie latter being due to a 
licown tiL By BOine it is supposed that the non-sajxinifiablc fat clio- 
Jesterino arises aa a product of waste, and that tJie phof>phorizcd oils, as 
boy are termed, constitute the white enveloping cylinder kno^^'n as the 
hite substance of Schwann, and tlial the interior cylinder is a nitrogcn- 
Ked but nor>-pho9phorized body ; but tlierc are reasons for suitpecting 
it the white substance of Scliwnnn is a non-phosphoriKed fat. and thai 
be axis rylinder contains the phosphoms in an unoxidizcd state, prob- 
ibly as a highly phosphurizcd protein body. Kvcry thing seems to in- 

S 



i 



274 



TE81CCIAK MATTEK. 



dicatc that Schwnnn'a snbst&nce only dischargca the physical duty of 
an isolator. The coincidence between the varjTiig activity of the hepp- 
oirs mechanism and the varying quantity of oxidized corapoiuids of pbtt- 
phoms in the urine indicates in a significant manner that tliis chemicil 
clement bears sometiung more than n passive relation to the prooeiui 
going forward ; and its kno^\ii occurrence in the vesicular structures, to> 
gcther with its extraordinary chemical relations, would prepare us lo ex- 
pect that it is, in reality, intimately concerned in all these plienoincita. 
Vcsieular ncrvuus material contains much less fatty matter than die 

« j^ * tubular, but much more water. Thus Ilauft* and Waltba 

Composldon of - , . , 

vMleaUrniat- fouud in tbc gnty substance of the bram trom 8j to &6 ptt 

'*''■ cent, of water, and only from 4.8 to 4.9 of tat; bat in the 

corpus calbsura they found 70.2 per cent of water, and from 14-5 to 
16.5 of fat. From such facts it would appear that the presence of fat in 
ncn-ous material is functionally connected with its pro|>erly of conJue* 
tion or transmission of nervous influence. In the brain of a child which 
died at birth, Schlossbcrgcr found that the coi-pus callosmn contuinudiu 
much water as the gray matter, and that, compared with the l*nuii of 
adults, that of new-born infants is richer in water and pcxner in fat. You 
Bibra ascertained that, within certain limits, the quantity of fat is con- 
stant in tbc brain ; that a diminution or increase of fat in other jnuIb of 
the system is not accompanied by any change in the quantity of brain- 
fat ; that the proportion of fat in the brain of man, other mammals, biids, 
amphibia, and Cshcs, diminishes in the order in which their names are 
here mentioned ; that the medulla oblongata contains the lan^t per- 
centage of fat; that tlic quantity of bratn-fat in old men is a little leu 
than that of adults in the prime of litb. lie also concludes that the 
amount of phosphorus in brain-fat is nearly the same in man, other mam- 
mals, and birds ; that its percentage In the brain of the insane does not 
exceed the mean amount ; that the vesicular matter contains more pho*- 
phoms than the white ; and that there is no special comiection betwnai 
the intelligence and the amount of phosphorus ; that tlie amount of fat in 
the brain of the ftetna is much less than that of the adult, tlie difference 
being made up by an excess of water, bnt tliat a great and sudden aug- 
mentation of fat occurs toward the end of foetal existence. 

Our attention may next be diivctcd lo the methods of repair ot the 
Mode of repair vcsiculoT Structures. Tlieir waste, as just established, im- 
of nervoiu plics their repair. Here, as in the muscular tissues, the 
wuie. blood-vessels conduct both operations, and the mode of dis- 

tribution of the capillaries is such as to bring the circiUating current into 
the most favorable position for discharging this duty. The rcsidea are 
included in the midst of a network of capillaries, and it is beJicvcd that 
thcrp is a rcsembknce between their mode of growth and that of the oella 



ue oBusj 

J 




CHOLESTERINE AND PHOSPHORUS. 



275 



ofrlie rpidcnnis; that is to say, they arise from nuclei on tlie spaces 
vbich are nearest to the supply of blood, and gnulunlly undci-go dorcl- 
Opmcnt aa they prcjwirc lor conueclion with the tabular tissue, assuming 
tht place of cells that have discharged their function and arc undergoing 
disutegration. This gradual passing onward and wearing away recalls 
t^ changes in the structure of tlie cuticle. 

To two of the substances thus met witli in these examinations of the 
nenroas Bratcm our attention may I)C nrofitahlv directed. „. , 

_- ', , y fl * ' J. CliolMlcrino 

These arc cholestenne and phosplioms. Of the former we wd pbo»]ii)o- 
caa not have fiiilcd to remark that it is a constant ingredient "^ 
in the product of ihe action of the liver. It is a lipoid, and is foiind in 
biliary calculi ; and though it may he regarded in one sense aa an excro- 
ncntitions body, since it occurs in fa?cal matter, yet it also appears as 
I Dormal constituent of the blood. It may therefore be inferred, if tlie 
9|union of its existence in the white substance of Bcliwann be correct, 
ihat it is one among the various functions of the liver to ])repnro this 
body. Of phosphorus it might be said, that it, among the ciicmical 
elemonts, is most strikingly characterized in its active state by the in- 
tensity of its ai^nity for oxygen. On tliis depends its qTiality of shining 
in tlic dark, a quality whioli has given it a name; but by many agents, 
for exnmph\ as cxpoFnre to a particular temperature, and especially 
the light of the sun, it may be thrown into a condition so completely 
tiist its cliemical energies disappear. The doctrine that was pre- 
In explanation of the destruction of one part of the system by the 
introduced by respiration while another is protected therefrom, as do- 
pendent on the allotropic condition of tliosc parts, is presented here again 
in disoossing the destruction and repair of the nervous tissue ; for it is 
eoly iHien it is nuidy to be removed that the pliosphonzcd constituent 
■nmes the active state, and in so doing gives rise to the development 
H force. On this view, it would ap]}ear that such phosphorizcd com- 
poondfl are obtained from the vcgctabtc kingilom in the food in a passive 
ftate, the tissues of plants having deoxidized them under tlie inllucnce 
of thn " 'it, whi(ji Himultaiieously has thrown them into the condi- 
tion f- ity, and perlinps it is the assumption of that very condition 
that is llie jfundamcjital cause of their deoxidation. 

k By the aid of the conclusions to which wc have come respecting the 
■Dclion of'neri'O-tubcs and vesicles, as betrayed by tlicir an- Funciiontof 
atotnical struclure, we shall not have much difficulty in ex- ner»-e^iu«ii| 

cviicliA con- 

plaining the offices of nervous arcs presently to l>e described. tld«mi «]««■ 
The resnits at which wc thus arrive, from a consideration of ^^i^*'/' 
thoae oells, are singularly fortified by the electrical experiments of Gal- 
rmnt, Volla, Xobili, and especially those of Yolkmaim. Among these, 
lliree following are of primary importance : 




Uie till 



S76 



3I,KMANN S Kl. 



MllCAL EXPERIMENTS. 



Ist. When n cotitiniiouH electrical current is jiasaeU along a centrifu- 
TollmiMin'» 5*^ nerve, coulractiou oi'tUc muscles wliich tliat rienx* su|i|ilics 
Kaultft. takes place, and continues as long as the electric current put- 
es, without relaxation, but ceases the moment the current is stopped. 

2il. Wlicn » continuous electric current is passed through a gxngUoii, 
contraction of the rauscles supplied by the centrifugal nerves of thai gaij- 
gliou cnsQcs. These contractions do not allenintc with relaxation, ind 
on stopping the current the contraction does not cease as in the pncol- 
ing case, but is continued for a ]K}nod of time. 

3d. When a continuous electric cnrront is passed down a cenirijieiil 
nerve, muscular contraction of the parts supplied by the correspondiit^ 
centrifugal nerves occurs, and these contractions alternate with irUx- 
ations. 

In view of thcae facts, wc are brought to two conclosionB : l-'irst, tlwt 
there is n property in tlie ganglion which enables it to hold in reserre & 
portion of tlio influence brought into it^ so as to keep up the action for a 
period of time nHer the original disturbing causes liavc ceased* Soconi 
that the structure of the ganglion is such as to pcjmit the escape of iIk 
coming influence by lateral ways, either periodically or otherwise, and so 
to produce from a continuous influence an lutemiitthig effect. 

Bccalling the tact that a ganglion is made up of ncrvc-tabci and vesi- 
cles conjointly, these electrical results must find their solution in the cJ- 
cmonfary structure of the ganglion, that is to say, in its vesicular por- 
tion ; for it is not to be supposed that n current of electricity, sut^i as vc 
are here considering, would ever have an opportunity of escaping iniBi 
the axis cylinder along whicli it passes. The isolating quality of llie 
white cylinder of Schwann would prevent any such effect. It is not nec- 
essary that wc should embarrass our^^lves here witli the fact that ^oc- 
trlc currents of sufficient Intensity could make their way out from tlie in- 
terior channel in spite of its insalating investiture, since it is only witli 
those of a far less power that wc have to deal. Arrived in the Tcstcjc^ 
the. current at once diffuses itsrif throughout the granular material, just- 
in tlie saiiic manner tliat it would <liffti8e throughout a spherical conduct—' 
ing mass if brought to it by a wire, and escape therefrom through anjr^ 
number of similar wires that might chance to be in contact with the con-^ 
ducting mass beyond ; and thongli the main l)ody of the current wouU- 
as may be readily proved, under these circumstances move in a direct 
line from the point of entry to the point of e^tit, there would bo neverthe- 
less a diffusion of part of it tltrough the conducting mass, no portion 
thereof remaining unaffected. In a good conductor, such ia a mctAl, thia 
laterally diverging current would instantly escape, but the case becomca 
very different in the less perfectly conducting material, the granular snh- 
fitancc within the cell. As in tlie secondary piles of Ritler, which* when 



AKATOMfCAt AND ELECTRICAL EXAMiyATIOX. 

irouglit info contact with an active voltaic circle, participate , . 
I all its qualities, pliysiologtcal and chemical^ give sbcckflf thL> Mcontlar/ 
trodacc decompositions, and continue to do bo for a time aft- P''** '*^ *"''*'• 
the originaJ influence liaa ceased, so a eimiiar conservation occurs in the 
nterior of the vesicle; and this 1 consider to !« the consequence of iho 
bflference of structure of tho fibrous axis cylinder and the granular vesi- 
Ic contents. Tlic continuous lines along which the infiucncc has been 
PDiing terminate on reaching the vesicle, and are replaced Xty a divided 
ind inferior conveying structure, a structure which recalls at once the sec- 
ndary piles of Bitter just alluded to. 

Wo may thci-eforo truly say that tlicso electrical expcriracnts offer a 
triking confimmtion of the truth of the conclusions to toin(irtfn«of 
rbicli we have come from the study of the anatomical struc- J"5'cl"ctric«i 
BP8 of a nervous arc. They assure us tliat a vesicle, and vximinaiioa. 
bFrefbre a ganglion, has a double otficc to perform, the stopping, reserve 
V storing up a port of the influence which is brought to it, and also 
veying of that incident influence into many new channels. These 
ions arc altogctlicr independent of any conception of the nature of 
nervous agent: it may be identical with, or allied to, electricity, or it 
be a totally diff<Tent principle. It is not that question which wo 
iccming ourselves with now. We are dealing with structure and 
. interpretation. Whatever our views may be of the nature of ituierva- 
in, we slmll find ourselves constrained to inter that the delays, diver- 
mcc&t detentions, and subsequent Burrendcr, the opjrortunity of diverg- 
ig from one into many new channels, or conversely tlipconvergencefrom 
Bany lines of entry into a single one of exit, with all ihc accompanying 
btcrfei^oees and reactions, tnust be common to both tiic electrical and 
ho nervous agent, for they depend, not upon the quitlities of those prin- 
aples, bat upon the anatomical structure througli which they are passing. 
With these remarks I proceed to on exposition of the typical construc- 
ion of the nervous eystcm, pointing out its successive com- nypotheticat 
dications. The hyi>othetical diagrams which I shall now ni".'!"''"^ 
irescnt are chiefly for the sake of impressing the conelu- auUi". 
liona at which we have arrivctl from a consideration of the structure of 
he nervous elements, fibrous and vesicular, the experimental dctermina- 
ion of those functions, and their electrical phenomena. That the-oc dia- 
grams are, however, somewhat more than imaginary 
skctclics, will bo obvious from a consideration of the 
nervous mechanism of the orticolata, wliich offers 
striking illustrations of them. 

The simple automatic nerve arc, J^iff. 122, consists 

of an afferent or centripetal fibre, a, connected contin- 

finyi* Auuinutfe 4K. uoualy with an efferent or centrifugal fibre, e. An 




T^. ttt. 




278 



SIMPLE A>'D UVVTIVLZ AJtCS. 



Pi8.-M. 



impression made on the free extremity of a instantly produces a co>^ 
traction in the muscular tibrc ;/<, wHicli the eft- 
rent branch e supplies. The wliolc force ii &t 
once consumed, no portion of it remaining. 

The simple cellatetl nerve arc, J^iff. 123, con- 
aistfl of ft centripetal libre, a, whicht receiving 
impressions on its five extremity, conveys tlioi! 
to the vehicle v, from wlticli the influence ps»e» 
forward along tLie centrifugal fibre «, cansing tk 
simt'ie ccUaM >rr. musculaT tibro »). wliicU tlic ncrvc snppli^ lo 

contract. An impression lundc at a tlienilore produces motion at j-l 
The action is purely automatic, and a part of the forco is stored up or 
rcriiains in the vesicle. 

In llie figures here given, the centripetal and centrifugal fibres are rep- 
resented apart In fact, however, they may be considered as bound lo- 
pclhcr, for t!ic sake of compactness, wiiliout tJiere being any fuaion a 
coalescence of structure or functions. It is also to be understood tlist 
the free extremity of the centripetal fibre is connected with some epccial 
mechanism adapted to the infiuence it is to receive. Thus its axis crl- 
indcr may be naked, or connected witli a vesicle, or with an appamtm 
for the reception of light, or sound, or heat, or pressure, &c. 

Multiple automatic nerve arcs arise firom an arrangement of many sucli 
simple arcs in succession longitudinally, as in /Vjr. 
124, or it may be in a circular order. Tlie former 
case is presented in the articulata, the latter in the n- 
diata. Each symmetrical portion of the animal lins 
its own nervous arc, but as such symmetrical ijorrioni* 
arc not deslined to live an iudcpendent life, but to act 
in unison witit the others, a necessity arises for eacli 

ore to 1)0 brought in relnlion and maintain a conneo* 
M«.ui-.u,r.o«c ^.^^ ^.j^i^ ^^^ ^jjj^^ ^^j ^^g .^ j^^ j^y extending 

from ganglion to ganglion fibres of communication, r, <?, which may Itcrc 
Cammiuunl hc Called commissural fibres. So tlie circle of ganglia which 
^^*'**- surrounds the mouth of tho radiata is not a circular arrange- 

ment of isolated ganglia, but a ring of ganglia and commissures conjoint- 
ly. Where the uen'ous system is plaiuied BymmctricaUy on tlic two 
aides of the mesial plane, the ganglia arc commissurcd across tlie plane 
to insure a reciprocity of action. Ju the molluscs, whoso organs of ani- 
mal life show this bilafcral symmetry, and which Iiave three such gan- 
glia, tlic cephalic, pedal, and parieto-splanchnic, each is commissurcd witli 
i(9 coUeaf^ic on the other side of the plane, or tliey arc brought uji to tho 
plane and juxtaposed, tho oonmiic^urc then disappearing, but tltcir bi- 
lobcd aspect betraying their separate construction. Tlic coalescence tirc- 



/V1SA. 





J 



CbMMISSt'EAL ACnOH. 



279 



J^. 19. 



fUn o( uta oommUnirnl. 
Fit- K«. 



qnently becomes more intimate, and all traces of the 
origiu&l double construction disappear. 

The lettcra reniuiiiing tlie same as in t}ie preced- 
ing diagrams^ J^l//. 12u represents the Tnanncr of 
commissuring across the mesial plane. 

As illuBtrations of the manner in which these 
mechanical principles axe carried out, the following 
figures are given. 
J*'iff, 12(», nenous flyetem of the lana of the sphinx li- 
gustri, showing the successive arrangement of mul- ... ^^^lg„^ 
tiple nerve-arcs from 1 to 11, commissured witli from various 
one another, and all with the cephalic ganglion *° 
17, which is their common register. 

Fit. lea J^ig. 127, the pupa condition of 

the same insect, and Tvy. 128 iho 
imago. (Newport) 

J*^i'f/. 129, ncrvona Byetcm of the 

m^^^»'^ , J,4!^ astcria.s, in its elementary parts. 

It consists of a series of five gan- 

glia, ff, ffi circularly arranged round 



F)ff. m. 



*=- 



'^r 



^ 



Kpttwm n«lm Koivou* ity^etn of NorroMa ■y^m o-f 






i luA Ku of sphlnz II- 



the month of the animal, and giving forth 
to each ray a pair of nerves. (Tiedemann.) 
rtfj. im. Fiff» 130, nervous system 

of patella: /,/, lateral ganglia, 
commissured with the cephal- 
ic, which is between them ; /, 
the transverse or subocsopha- 
»«»«. ,7*.^ of gc«I ganglion, commissured in 
^"^^^ like manner. (Cuvier.) 

^g, 131, nervous system of sepia octo- 
pus: c ceplialic ganglion; o, p, optic gan- 
glia ; g, suboesophagcal ganglion ; /, l, lat- 
ctbI Btellate ganglia; a, abdominal or vis- 
ccnl ganglion. (Cuvier.) 




NtTTViu irattB of litorfaa. 



L 



XAtow tcjtUBi at acto|»iii 



2S0 



coaoussuiuL jicnoN. 



Fig. 132, nervous system of aplysia: a, an- 
terior ganglion ; c, ceplialic ; /, /, lateral ; g^ 
ulHlomitiaL 

III tUc mpclianiciU interpretation of the ncrv- W I p i ^7/ 

Function of 0U8 Bystcm, thc action o( coniinis- 
conuniMurm. ^xiitv\ Btrantls IS ft point of primajy 
importance. It may be said that they are for 
the jiurposc of drawing otVfrom iho nerve arc a 
part of tltc infiucnce which is coming along tho 
ccntrij>ctul tihrc, and dinK:tiiig it into a newchan- 
nel. if such coarse illustrations arc ]>ennissi- 
We, tho vesicles act like a tliree-way cock, or 
perhaps like a piece of looking-glass with a 

jNirt of thc foil removed from its midst; a K«mMM«jiteaior»pty^ 
beam of light impinging upon it is in part rctlcctedi and part escapes 1 
liind tlirough the uncovered space Tliough I liave deschbcd the simpfe 
ccllated ner\'c am as containing essentially a ganglion or vesicle, it is net 
to be supposed that such a structure necessarily impresses any chugi 
ou tho incoming influence Since, tf wo irritate a centnpetal fibre, mus- 
cular motion may ensue from propagation of that irritation through tlM 
ganglion, and if wo irritate a centrifugal fibre, muscubr motion equally 
ensues, it is quite clear that in thc so-called action of reflection by the 
ganglion thcro is, in rcalit}'', no cliangc in tho intiuence whicli has 1>eeo 
brongijt along the centripetal fibre. Thc same impression on any part 
of thc nervous arc, no matter on which side of tlio ganglion it vniiv be 
made, will produce thc same muscular result. 

Such considerations therefore lead us to suspect that nothing takca 
Act «f TvHec- place in thc ganglion which justifies such an expression aa 
tion. *4, n(.{ pf reflexion" or ** reflex action,'* terms whlcli eo.ivcy an 

idea that the influence wliich passes in thc two branclics of the nerre 
arc is difll-rent, the difierencc having been established or brought on by 
thc ganglion. Tliey confirm the opinion ttiat the gangUon has, for one of 
its primary duties, thc function of permitting an escape of the influence 
passing in the interior of thc centripetal fibre into new channels for the 
establishment of new results. 

In the simple automatic nerve are the impression and the effect aie in- 
imiunitiiBotw stantaneous. An irritation of tho centripetal branch pro- 
«ction nf tbu duces, without any sensible internal of time, muscular con- 
» inp P »rv. traction tlirough the action of the centrifugal branch, and that 
contraction ceases the moment the impression is over. But the open* 
llwm<i»c(loQ ing out of the nerve arcs by the introduction of a vesicle 
of eolUtcd «rc«. permits a part of thc influence, whatever it may bo, to be 
drawn off, and this, now passing along the commissural line, may be dis- 




REOISTEWXO SERVE JJtC 



I 
I 



JV. 133. 




pOBod of in two rliffercnt ways : 1st. The influence thus drawn off may 
bo iiistantaneoufily consumed or utilized by exciting, through adjacent 
simple Ares, synchronous movements ; ori 2d. It may Le held in rcsen-e 
for future use by being carried along the commissure to a receivuig, or, 
as I mav term it, rc^stcriiig ganglion. 

This, therefore^ intro<luccs a more complex mechanism, which may be 
designated as. 

The registering nerve arc, the typical construction of which is rcpro- 
scntcd in Fr^. 133, In tliis we have tlie Rcfc-isiering 
centripetal, «, and centi-ifagal fibre, e, as be- "*f*« *"*• 
fore, in connection with their central vesicle, v; but, 
passing from that central vesicle, a commissiiral fibre, 
<•, offers a channel of escape of a port of the influence 
which 80 roaches the registering ganglion, r\ and makes 
a permanent impression upon it by tUsturbing its con- 
tecii«MUi« MIT* are. ^(jon phvsically or chemically ; and, since many ncrv- 
oas arcs may be thus cominissured upon the same registering ganglion, it 
thus Iteconies for them all a central jwint of deposit and a centre of com- 
mon action. And in this manner not only is a temporary VarUbt« tt- 
inflttence converted into a permanent impression, but, from [^-'*riaij/i^ 
the interaction of sncli impressions upon one another, new iTc»ioi». 
and variable results anse. 8ome illustrations were given a few pages 
back of the development of the variable from the invariable in tlic case 
of certain ordinary physical phenomena, and tliesc may be profitably re- 
ferred to again. 

A modification of the registering nen-e arc is presented in Jut/. 134, 
FVy. lat which exhibits the suppression of tlic centrifugal ^^ ^,,re»,i„n of 
branch, the whole inflaencc received passing along crii:rifu«ai 
tiie commissural line to the registering ganglion. '*"^ ' 
Tliis condition of things may occur when tho centripetil branch 
at its free extremity is involved in a ineclianipm of spo<'ial 
sense, olfactive, ophthalmic, or auditory. No part of t!ic ini- 
IiTCssion thus received is necessarily cxjiendcil at once : the 
supfm^ua whole may be thus retained, and utilized at a future time. 
KUbrudi. The introduction of the rcgislenng ganglion is thus the m- 
trodtiction of the clement of time in a living mechanism. In the lower 
forms of are an impression is instantaneously expended, in tliis it is pr&-' 
served. 

The common centre or register of whatever impressions have been ro- 
ceivwl by tlie special sense instruments, oltiictivc, ophthalmic, or auditory, 
as well as impressions of a general tactile kind, is doubtless 
to \te properly reganled as the ReiiHorium. Though animals 
constituted on this tj'pc accomplish many vuriaijle actions, that variabil- 




283 



THE JKPLI*ESTUI. AUG 



ity is osscntiolly ami purely automatic. A» sucii may be regaidod llie 
instinctive actions of becs^ any two of which, if placed under the ssnc 
circumstances, act with undcviating certainty in the same way, Tbc 
whole career of lite of one of these insects is the whole career of any otli- 
er. Tlioy build llieir corahs now in llie same way that they did a tlioii- 
sand years ago ; their daily doings arc the same as they liave ever been, 
Kxccpt as TeffCCts a particular, hercat'tcr to be pointed out, they majle 
regarded as automatons. 

The introduction of a registering ganglion necessarily gives riae to an 
Kttortorthoin- extension of the physical relations of an animal by connect- 
.i^JJ^-riT-" * *"S ^** present existence with antecedent facts, for the gan- 
' gaofjEiion. glion at ajiy moment contains the relics of all the impres- 

sions that have been made on it up to that time, and these exert their iii- 
flnencc on any action it is about to set up. In virtue of them, the nen- 
ons mcclianism has now the power of modifying whatever impressiolu 
may be made on its centripetal nerves, and, within certain limits, of con- 
verting them into different re^iults. Yet still the automatic condition is 
none the less distinct, and still the initncdiate source of every action is to 
be found in external impressions. 

An increasing complexity of nervous structure is next evidenced by* 
SooMtryud division of the registering ganglion into two portions, whicli. 
BMCerlobc*. ^ji, gQ0]e incorrectness, may be designated sensory and mo- 
tor lobes, a division which is preparatory to, and, indeed, obviously con- 
nected with, the introduction of a totally new method of action and sooree 
of power. 

In J^iff. 135 we have an ideal sketch of tliis new condition of things. 
piy. no. "^^'^ letters used in the preceding cases, in tliis refer again 
to the same parts. But now it is seen in addition tbil 
the registering ganglion has assumed a bilobeJ aspedt 
8 w», the letters respectively indicating its sensory and mfr 
tor portions, or, to use the languo};^ of human anatomy, i 
thalamus and corpus striatum. From these there hrandi 
off commissural lines, radiating to a hemispherical collec- 
tion of vesicular matter, c c, the representative of a cere- 
brum. 

Assuming the registering ganglion as a centre, the txc- 
like arrangement on eitlicr side of it is symmetrical, as is shown in J'ig- 
Thpinanfln- 135. And since it will facilitate our consideration to intro- 
tuiarv. ^^p^, iigyc distinctive terms, I shall designate the external arc, 
wiiich is in relation with the external world, as the automatic arc, and 
the inner one, which is in relation with the cerebrum, the influential arc. 
Tlu-oughout this work I have constantly assumed the existence of an 
intellectual principle, spirit, or soul, whose links of connection with tlie 



o 



lajtauutlal kv. 



J 



OP THE EXIBTBWCE OF THE SOUL. 



lextfmal world arc tlie sensory ganglia and tlic cerebral Evidenwofrbr 
ilicntisplici'cs. We may now protitablv inquire whether any pxiaieoccofihe 
|<tfgttnient in beiialt o\ the existence of such an agent ma/ rramranibral 
lie g»tlicrc«I from tiie anatomical and physiolo^cal I'aclB just "t^t^uf*- 
||>reacute(l, or whellier wc must assume it as a postulate, relying for proof 
K>D evidences of a totally clitlcrcnt churacter to those which are presented 
%y tlic acience now engaging our attention. It is to be greatly regretted 
that evidence drawn from structural arrangement lias hithertOt by very 
ibigh authority, either been totally cast aside or held in very light esteem. 
It is still more deeply to be regretted that those who should have known 
ibetlcT have or>uceded the argument that from no consideration based 
mpon anatomical or structural arrangement could proof be obtained of 
ilte existence of au immaterial principle. Kvcn by sucli, the study of 
^jsioiogy has been designated as leading to materialism, and« witli an 
injasticc which can not be too emphatically reprobated, the scandal has 
loften been quoted, tliat where there aro thiec physicians there arc two 
Atheists. 

I Dut what if it abould turn out that, from the study of the cerebral 
(mechanism, distinct pnx>f can be obtained on tliis point- — proof of just as 
JMgent a nature in support of the doctrine of the existcuce of the soul 
ks tJiat which we have of the existence of tlie external world, and of pre- 
oaely^ the same character? Without, therefore, occupying myself with 
Ivocb other evidence as might be drawn f om theological or metaphysical 
WmrccB, and whicli are thcrctbre extraneous to the object of this work, £ 
shall proceed to ]>oint out ouch considerations as naturally offer them- 
iselves to our minds when we recall the general structure of the nervous 
iftpparatus. Hei>eating, therefore, such facts as may be necessary for the 
Mropcr understanding of this uitcresting argument, I present it as follows: 
I The simple cellated nervous arc consists essentially of these portions, 
« centripetal fibre, a vesicle^ and a centrifugal fibre ; the cen- j^^,^^, ^.j. 
tnpetal tilwe may liave at its outward or receiving extremity nwcimium of 
jvmicolar or cellular material. Tiiua constituted, this mech- * **"" "** 
lanUro is ready to receive external impressions, which, if such language 
jnay be approprintely used, are converted or reflected in pai-t by the gan- 
Iglion into motions, and the residue retained. IJut the arc, viewed byit- 
•cll'. is a mere instrument, ready, it is true, for action, but possessing no 
interior p>wcr of its own. It is as automatic as any mechanical con- 
Itrivancc in which, betbrc a given motion cau be made, a certain spring 
isnoat be touched. 

i. The essential condition of the activity of such a nervous arc b thero- 
ifcre the pre«enoeaud inllucnce of an external agent — a some- jj^„i„, ,„ 
Itliing which can commence the primitive impression, for with- Kxtarnai igtot 
|Out it the meclianism can display no kind of result. 31ore- 



fvr OCtioD. 



2%. c 1XVERSB FHTSIOLOGICAL PSOBLEMS. 

ovcT, there must be an adnptatiou hctvreen the naturo of thnt agent tnl 
the structure tlms brought in relation with it, as 13 strikingly illustrate! 
by each of the organs of sense. Thus ihc peripheral extremities of the 
tibrili; of the optic ncn*c arc involved in a combination of a purely pbvs- 
ical kind, having relation to the projwrtics of light: the convex suitaos 
of the cornea, the unequicun^d lens, the diaphrB^ntic iris, the tnteiioi 
investiture of black pi^cnt, these are all structures the object of which 
we cleariy understand. \Vc know that the rays of liglit must undergo 
i-cfraction at the curved surfaces upon which tliey are incident, and de- 
pict the images of external forms on tlie retina or black pigment, the irii 
expanding or contracting, as the case may be, to regulate the entrance of 
A<i«|ititim) he- the light. So completely do we admit this principle of M 
ln7ui?"ch"' at^T^at'on of atructure to the nature of the agent which is 
iiiiiMa. to set it in activity, that in this particular instance, ^vitiioat 

any hesitation, we class the eye among opticjd instruments, and incluie 
lis description in our optical treatises. Hut in the same manner that, 
starling from the well-known properties of light, we advance to Ihc ex- 
planation of the uses of each of the various jmrts of the eye, thei-e can bo 
no doubt that tlie converse of lliis mctltod of reasoning would be possi- 
ble to an intellect of sutficient power, who, from a full consideration of 
the structure of the eye, miglit determine the properties of light, goided 
in doing this by the principle that there must bo an adaptation between 
such structures and sncli properties; and, in (lie same manner, a nun 
deaf and dumb, but of an intellect of great capacity, might donbtless, 
from the critical study of the construction of the ear, determine the na- 
ture of sounds. Nay, even more, it is not impossible that he should be 
iible to compare together the physical peculiarity of llie movements which 
constitute light or sound respectively, and to demonstrate that these 
originate in normal, and those in transverse vibrations. 

tio, tlicreforo, tliesc problems ]>reftcnt themwlves Ainder a doable aspect, 
XaiuTTorio- and arc capable both of a direct and an inverse solution: 
?(S^*'irfS!^ Given the nature of ligiit, to determine what must necessarily 
l«a». be the constniction of the organ of ^^^ion ; or. Given the con- 

struction of the eye, to determine what ia the nature of light; and the 
same might be said of tlic organ of hearing. Tliis inverse method of 
treating natural agents is still in its infancy, l>ccau8c of the extreme im- 
])erfection of our knowledge ; but donbtless wiiat has been said will r^ 
call to tlic mind of the reader tlie parallel example which is furnished by 
astronomy, and which, within a tew years past, has yielded such a splen- 
did result. The mass of a planet being known, tiio perturbations which 
it can cause in another arc cajKible of direct computation, but it was re- 
served for Lcven-ier to discuss the inverse prctblcm, and from the per- 
turbations to find the place of tlie planet, Tlie discovery of Neptune 
wns the result. 




OF THB EXISTENCE OF THE BOHL. 



tss 



I 



I 



I 

I 



TbeMBl. 



Xow the problem we arc dealing witb is of this inverse kinJ. It may 

be sUitcd, Given the structure of the cerebrum, to dctcnnine the nature 

of tiie agent that acts it in action. And licrein the fact which cliipny 

guides na ia the absolute analogy in conatruction between the clcinentaiy 

urmngcuicnt of tite cerebrum and any other ncr^-oas arc. In it we pluitilv 

ncoguize the centripetal and centrifugal tibres, and their con- Extenml imtu- 

Tci^nce to the sensory ganglia, the corpus striatam and f"r J^*^,"!!^', , 

optic thnlamns; we notice the vesicular material at their liainm 

external periphery as presented in the convolutions of the human brain ; 

ftod if in other nervous arcs the structure is merely automatic, and can 

display no phenomena of itj^clf, but requires the influence of an external 

agent — if the optical apparatus be inert and wiihout value save undur 

the inflaencea of light — if the auditory apjiaratus yields no result save 

under the impressions of sound — since there is between these stniclures 

and tlic elementary structure of the cerebrum a perfis;t analogy, we are 

e&tiUod to come to the same conclusion in this instance as in those, and, 

aaaening tlie absolute iiiertncas of the cexebral structure in itself, 

to impute the phenomena it displays to an agent as i«?rfectly 

external to the body and as independent of it as are Hght and sound, 

and that Agent is the soul. 

It would not comport with the olyect of this work to pursue this ar- 
gument in its details, yet I can not forlxxnr observing that, even so far as 
wo have already advanced, t!ic point which, al'ter all, is of the utmost 
importance, is completely attained. Those who have accused physiology 
of tending toward materialism Iiave never duly weighed tlie accusation 
tkey make, and certainly have never undcretooil the nature of the argu- 
ne&ts it can present ; for such as the one hero imperfectly set forth, from 
thor tangible nature, will commend tlicmselvcs to many minds wlio do 
not appreciate the strength of purely metaphysical arguments, and herein 
they may become subsenient to the highest and most enduring interests 
of oiir race. 

And thus it may l»e proved that those aclions which wo term intellectual 
do not sprinjT from mere matter alone, nor ore they functions , , , 
of mere material combinations; for though it is indisputably and immorul- 
troe that the mind seems to grow with the bodily stnicturo, "^' **^ "*" **"'* 
and declines with it, exhibiting the full jwrfection of its powers at the 
period of bodily maturity, it may be demonstrate! tiiat all this arii«es 
from tlie increase, perfection, and diminution of iho instmment tlirough 
which it is working. An accomplished artisan can not display his |M>wcr 
through an imperfect tool, nor, if tlie tool shouKl Ijc broken, or become 
QMlttss through impairment, is it any proof that the artisan has ceased to 
cxi«t; and so, though we admit that tliCJC is a correspondence lietween 
the development of the mind and the growth of the UmIv, wc deny that 







it follows from that, either that the mind did not pre-exist, t 
death of the body implies ita annihilation. 

IT it fell witiiin the compass of our plan, we might proceed to cotuidei 
'loioo WW ^'^"^ ^'^' ftinoc the mind can act upon externa) nature thro^ 
Bjxciiiiit tiic the intervention of the bodily tnechanism, the convciw it 
loaUoIlIrtniD. po^ible ; how, since the face of things around us can U 
ed bv (litTeroot changed by our volunlar}* exertions, tlie intellectual faculliei 
may be ciiangcd by the action of external nature through the 
bodily mechaniam. And since we ha>'c established the existence of the 
intellectual principle as external to the body, we might proceed, for now 
wo are entitled so to do, to reason respecting its nature trom the phenom- 
ena it displays. 1 do not, however, pro]M>sc to enter on those considcn*- 
lions now, and shall close these remarks with a reference to some doc- 
trines pro])oscd hy the most liighly-advaneed and inloUcutuul portti 
the human family. 

It ia said that the ppirit of mnn is created in the image of God, 
servation eirtkingly illustrated by the fact that, as regards both, two ea- 
senlially different doctrines have been held — the pantheistic, by some of 
the most highly advanced of the Asiatics, snd the anthro]tomor|>hic, br 
the ICuropcaus. The pantheistic su])poses tho buiuan soul to be a part 
of the Deity, and thcrdbro devoid of form ; the anthropomorphic as hav- 
ing the likeness of the body. The Asiatics, then, regnrdinj; the Dciiy m 
a principle dltfuscd in and tluroughout nature, consider the spirit of msn 
n» a part or portion thereof, and often use sucli illustrative allusions as 
those of a drop of water in the ocean, a spark of a universal and vital 
itamc ; or, if they do not accept this view of a oneness in tlic nature 
spirit and Deity, they regard the former aa arising in some tDanncr fi 
the latter, just aa waves may exist upon the sea, or sounds may arise 
the air. They believe that at death there is, as it were, a rennion of 
{mrt with the whole, as every drop of water sooner or later iinds its way 
back to the sea, or waves l)ocome quiet and disappear, or sounds die a 
in the air. 

But with Kuropean nations there has been, from their very infancy^ 
tendency to the anlhn^pomorphic conception. The barbanans before the 
Komnn empire, in their legendary- fables, accepted the idea of dUembod- 
ied spirits under the sliapc of men, and through the inter\'ening ages ap 
to our own times, such notions, under various forms, luvc bt^n lield. 
The rural populations entertain an undoubted faith in fairies and g^hosls, 
80 that it might be asserted that this manner of viewing tho thing is 
almost natural to us- We instinctively represent to ourselves in tliia 
way the immaterial principle, and in the case of each individual expect a 
corre3|K)ndence between it and his bodily form. Whatever may be our 
authority for arriving at such a conclusion, there can be no doobt that it 



ntal 

i 

way 

J 




ORGANS OF SPACE AND TIKE. 



387 



I 



I 
I 



so specializes and intensiHea our ideas, and is so connected with many 
of OUT most highly cherished recollections, that, even were the evidence 
in ita belialt'iiu- weaker tlmn it actually is, we should look without favor 
on any attempt to iuvalidate the doctrine, and, if forced to do so, should 
abandon it witli regret. The jianthciatic ia a grand but cold philosopli- 
ical idea; the anthropomorphic embodicfj our recollecliona, and rc-stoi-es 
to US our dead. The one ia tlie dream of tJie intellect, the other is tho 
hope of the heart. 

We have thus traced out the esaentiai elements of the nervous m»- 
cluiie in its highest complexity, and shown its gradual rhse luiiMTfcction 
from the purely automatic to the influential. We may there- "J'n^fopj'.^io. 
fore comprehend the difficultiea under which metaphysicians itou». 
Ubor, who confound all these i^arts and all these f\inctions together, and 
poas over as of no account the guiding indications which are iurnished 
by the study of structure It ia not difficult for the j)hy8loIogist, en- 
liglitened by the knowledge he possesses, to recognize the various points 
at which tlwse philosophera go astray — the point at wluch iheir theories 
cease to be rcpresentationsof the truth, lie acknowledges the existcnco 
of an extcinul nature, and equally the existence of an imniateriul spirit, 
and to their action on or relation to each otlier he traces the resulting 
phenomena. He admits that, among certain classes of life, every motion 
and everj- scnsalion ia due to external nature alone, but to tliese purely 
automatic groups man does not hclong. He repudiates tlic doclriiu'is of 
the idealist, because, tliough they may maintain themselves in the uncer- 
tainties of metaphysical argument^ they are dissipated at once in the more 
severe trial of anatomieid discussion. 

Tiicre are two fundamental ideas essentially attached to all our per- 
ceptions of external tilings: they are si'ACE and time, and rroTisionimu 
for these an early provision is made in t!ic ncnous mechan- r^TiiMVof '*'" 
ism, while yet it is in an almost rudimentaiy stale. The fp*™ apd time. 
development of tlie eye and tlie ear, as we simll more particularly find 
when wc come to the description of these organs, is for tlds purpose. In 
a philosophical respect tlie eye is the organ of space, and tlic e^ir of time ; 
the perceptions of which, by the elaborate mechanism of tliese structures, 
become infinitely more precise than would be possihle if the sense of 
touch alone were resorted to. The indications tims gathered are trans- 
milted by the optic and auditory nerves respectively to tlic brain. 

In its highest condition of development, the nervous mechanism has a 
threefold operation, objective, subjeetive, and tnijiersonal. orj«ciiva,vab- 
Objeclivc ideas arise in external facts ; subjective in register- Ki^j^'^op. 
ed impressions; the impersonal, as, for example, the abstract cratioo*. 
trutlia of geometry, issue of pure reason, and arc therefore to be attrib- 
uted to the essential nature of the souL Of these three elementary con- 
stituents all human Icnon'ledge consists. 



288 



TESnOES OF QANGUOKIC IJHr&fSSIOSS. 



Aft respects Hubjective or registereO. impressions, a few rctnorka mar 
, , be here made. There caii not be a doubt Uiat the recisw 

lIlMtralionsof . , ■ .* 

ih« veMigu or of impressions involves an actaol structural chiingc m tw 
iiiipmwuft). ganglion, which is of a permanent character. These chaogct 
mar be rudely and imperfectly illustrated by experiments, such aa Ipob* 
lishctl years ago, of wliich the following may be taken as examples: U 
on a cold, polished piece of metal, any object, as a wafer, i^ laid, and ibe 
metal then bo breathed upon, and, when the moisturo hiia iiad time ts 
disap|>ear. the wafpr be tiirown off, though now upon tlic jiolishcd surfius 
the most critical inspection can discover no Imoe of any fonn, if wo 
breathe ujKin it a Bj^ectral figure of tlic wafer comes into view, and Uiii 
may be done again and again. Xay, even more ; if the polished metal to 
carefully put aside where nothing can deteriorate its surface^ and be so 
kept for many months (I have witnessed it even after a year), on brvalh- 
iug again upon it, tlio sliadowy form emerges ; or, if a sheet of pa.i>tt an 
which a key or otlier olyict is laid be earned for a few momenta into tfaa 
sunshine, and then instantaneously viewed in the dark, tlie key being 
simultaneously removed, a fading spectre of the key on the paper will be 
seen ; and if the paper be put away where notliing can disturb it, and 
80 kept for many months, at the end tliercof, if it be cairied into a daA 
place and laid on a piece of liot metal, the spectre of the key will coivk 
fortli. In the case of Iwdies more highly phosphorescent than paper, the 
spectres of many different objects wliich may have been in successioo 
laid originally tliereujKin will, on warn>ing, emerge iu their projjer order. 
I introduce these illustrations for the pur})Ose of showing how trivial 
ore the impressions which may !« thus registered and presented. li>- 
dced, I Ijclievc that a shadow never falls upon a wall without leading 
thcrcujx)n its [>ennancut trace — a trace whicti might be made A*isible by 
ri'sortijig to ]»ro]KT pix)ces8e3. All kinds of photogmphic drawing are in 
their degree examples of the kind. Of the moral consequcncca of such 
facta it is not my objoct liere to speak. Tho world would be none the 
worse if cvorj- scrrct action might thus be made plain. But if on such 
inorganic surfaces impressions may in this way bo preserved, how much 
more likely is it that the same tiling occurs in the purposely-constituted 
ganglion! Not tluit there is any necessary coincidence betwe<^n an ex- 
ternal fonu and its ganglionic impression any more than there is be- 
tween the letters of a message delivered in a telegraphic office and the sig- 
Intarpreiaiion ^^ whioh the telcgniph gives to the distant station, yet these 
oTsBchTM- sigiuds are cjisily relranslated into the original words — no 
***** more than there is between the letters of a printed |Migc and 

the acta or scenes they may chance to describe, but those letters call up 
with clearness in the mind of the reader the events and scenes. Indeed, 
the <xuickncss with wliich the mind interprets isach traces or impreaaiODS 



BPONTAKEOra mfCTTOXS OF GANGLIA. 



2SS 



Ik its registering ganglia is illustrated by the rapidity with which we 
»lher the sense of a printed page without individoalizing each of the 
nters it contains, or as a ukilll'ui accountant runs his eye over a long 
)iuinn of figures, and seems to come by intuition at once to thc> correct 
im. Tbe capability whicli we thus possess of determining a final per- 
iption or judgment of result^ without dwelling on tlie intcnnodiato 
■ees or steps, is also illustrated by our appreciation of music without 
mcentrating our thonghls on the time and intensities of vibration or in- 
rlercnces of the notes, though these matliematical relations are at the 
rry bottom of the harmony ; and conspicuously does the Supreme In- 
U^genoe, Clod, reach with unerring truth to every final result without 
ly necessary concern in tlie intermediate steps. 

Krom the preceding considerations we may infer that there is a neces- 
try limitation of the amount of impressions capable of being j..^. 
igistered in the organism, and therefore, in this regard, all or human 
bnuui knowledge is finite. Yet its term is much farther off ^'"***«'k^ 
Inn might at tirst sight appear. A hbrar>' of a given size may only be 
jble to contain a given number of books upon its shelves, but tlie amount 
I information it is capable of containing may be made to vary with the 
Indentation and perspicuity of the books. 

r In the hypothetical langtiage of physiology, the nervous centres are 
boken of as the origin of tlie nervous influence or force, A cootiiwioo n- 
loee examination of the phenomena they display leads us, "p^iin* **• 
lowcver, to receive such a doctrine with a certain amount function gf 
i limitation. Most of the ganglia produce no motor im- B«nel»*- 
jklaes except under the action of external impression, and under the el- 
■Mntaiy view wo have just presented regarding the function of the 
nil), the same remark aj>plics even to it, since the immaterial principle, 
^ose instrument it is, must be regarded as an agent distbct from it, 
tod in that resiiect external. Indeed, the cases in whieli the nervous 
Iftitres seem to display the quality of sjwntaneously originating force are 
n few, and in their nature so doubtfiil, that we are almost entitled to dia- 
l^ard them. For example, tlie ganglia of the heart are by some sup- 
jmd to cause, by their own inherent power, the contractions of that or- 
pm, which in cold>blooded animals, long ai^er it has been excised, will 
nntinue its rhythmic motions. But it is far more agreeable to the anal- 
Igies of the nervous system to rcgartl these cardiac ganglia, not as ori^ 
Batons of power, but as merely depositories, reser\*oirs, or magazines of 
L There is nothing more extraordinary in their ability to keep up the 
' otions of the organ with which they are connected than there is in the 

ibsidiary spring of a chronometer, which maintains the movement of 
it instrument for the period during which the action of the mainspring 
p taken off while it is being wound up. Yet the mainspring, and the 
J T 



MENTAL EMOnOSS. 



saTjsidinry spring too, derive their meclianical power originally fromtlie 
Ibrce which lias wound up the clirononicter. In this particului of \ht 
storing up of power for its utilization in the time of need, the whole pxir 
glionic or sympathetic system of ncnca may be taken as the great ex- 
ample. 

The conveyance of an impression through the great nervous centres is 
„ , , moro complicated than it is throneh the nerve trunks. It 
ftciion oTiwrTt may be conducted, il of sunicient mtensity, through one gM* 
oMins. glion after another in succession. The intermedium ihrongii 

wliich this ia done is probably the ner^'e-tubes in a majority of inslanceh 
tlioiigh perliaps, in lliosc casea iu which a longer period of time ia occi- 
pied, it may be rnthcr from vesicle to vesicle than through the tubes. 
Impressions may be thus transferred from one set of tubes to otbaSf oi 
Cm\'vrMOB of they may be tUffuscd from a ncnc centre to many tubca 
tbmu^cra- around, and so produce a wider circle of influence. Tliit 
tn^ transfer of impressions from centripetal to centrifugal fibni 

which lias been previously described as rctiex action, though conimonlr 
involuntarj-, may in many instances be governed by a direct exertion of 
the wilL Thus tho respiratory movements for the introduction of air 
may be controlled to a certain extent, as in holding the breath, but tia* 
is only during a short time, for the necessity of permitting the nonnsl 
action to occur presently becomes insuperable. Of reflex actions, the 
majority arc obviously for tlie accomplisliment of some special object so 
long as the system is in health — they arc means for an end; but in dis- 
eased conditions they very often occur in an objectless or useless way. 

In its most perfect condition, the nervous system thus consists of nro 
NRtnni of men- separate mechanisms, the automatic and the influential, and 
111 omotioiu. these arc eo related that they can mutually act on one an- 
other. The will can exert a control over the so-called reflecting func- 
tion of the automatic part, and external impressions which have booi 
received by that part can exert a reaction upon tjie will, Il is in thia 
way that mental emotions may be explained, the [Xiwcr of external inflo- 
cnccs which antagonize or even overcome tlio will. 



THE SPIRAL AXIS. 



291 



CILVPTEU XV. 



I 



TIIE snXAL AXIS. 

Awkw* Dettlo/tment o/'AmtNa Sjv/mi. — IlsJiMoi OmSticn in tPjrereot Vaithratrs, 
T^tSjiiMil Cordi it« Structarf. — //* MnnhniMii. — Itx Thin^-oM Pairt af Srrvtu. — Pnptr- 
ab« i>f'tknr Root*. — /mffioM of the t'ord. — iicltM Dinr^-rry, — Tmntmumim nf /jurt^twiimjt 
'madTrmutrrrxe. Tn/iunrfn. — JJijJfxArtlmttftht Orrtl — Sattmof Bffltx Action. — i/bftw and 
Smumry VnuJa uf the (.hrd. — ^vtHtniiry of its Functhw. 
JTit Mt^tMlit Olitiitgata .• its :Struftwc and f'laiciiorui. 
71« /Vm« I'aroiii: iu Stnrtfm and J-'mtrJieiu. 

Zir, Otrjteut*r'a Vienrt of tAo Anahgtf Uttnttn the Spiaai CWJ of VrriAnUea and th» Vttilral 
Conl a; ArtictduteM. 

AVe now coramencc a moi-c tlclailed examination of tlic nervous sys- 
tem, presenting a description of its stnieture as far as may s„i«uvi»ioiii 
be necessary for the uiidcrstantlin^ of its functions. Wc **^ "'" "»''>"-"*• 
follow the usual division of this subject as adopted l>v authors, 
will therefore lead us to sjieak in succession of tlie spinal cord and 
medulla oblongata, of the scnsorj' ganglia, of tlie cerebellum and ccre- 
bnim, of the uenxs generally, and, lastly, of the BjTn pathetic system. 

The important position occupied by the nervous nifclianism in the an- 
imal body will always draw to it the closest attention of the physiol- 
ogist, and yet it must l>c admitted that hitherto it is the le-ast ad- 
vanced portion of the science. If metaphysicians are to be blamed for 
casting away the advantages winch arise from a study of Adr*nuge«deL. 
structure, the earlier physinlnglsts were almost erjually in Jmrouj^h^-^I 
error in confining themselves to Iniman anatomy alone, "lopf. 
They did this under an impression that there is an essential and intrinsic 
difference between the functions of this system in man and in the lower 
animaU. 

There is an anidogy of construction in all the forms of ner\'ous system 
presented by the different aniniul tribes, which, in the inlancy of the sci- 
ences of orgnnizalion, was attributed to a unity of design per%"ading tho 
jJan of Nature, but which, when seen from a higlier and more philosoph- 
ical point of view, is plaiidy tlic neeeasaiy result of a universal and un- 
^■arying law of development. This conclusion, wljich, when better un- 
derstood, is doubtless destined to become one of the most important sug- 
gestions ever fumislicd by science respecting the management of tho 
world, is strikingly enforced by t!ie analogies between tho ^^j^ , 

wocessive transilor)* stages of development of this system rivM rhim de> 
at different epochs iu tho life of man, and the permanent **'"'l""*"'- 
form it assumes in members of the entire animal series. Since ther > con 



DEVnLOPMENT OP THE CEREBE0-8PIXAL AXB. 



l)c no doubt tliat every animal function, irom the aatomatic rootions cf 
tJio ob&curcst living form up to processes of intcUcctiou of inaiL, tlt>fimi 
upon tiiis structure as on an instrument^ i^ uiaVf by a due coniparbon of 
the Iiabits, instincts, or other phenoRiena in such cases with the existing 
nervous (levclojmicnt, arrive at true conctusiona of the connection between 
its stnicture antl its functions. Wc shall therefore indicate, in a 
manner, the onler of development of this sj-stcm in man, and 
permanent stage3 in tlic aniinni scries. 

The nervoud uystcin first niiikes its appearance in the serous lr^imn;i 
CmneofiUi- of the geruiiiial mombrano and in the midst of the ; 
humft'n'n'Jrv- "^^ ** *^'*^ primitive tmce, a delicate nnd pale-white lii^ rie- 
oun'vio^-m. ing somewhat above tbc general surface of the germinal ant. 
This line soon presents a conical as]M!ct ; the thicker |>ortion U de^lind 
to become tlic head of tlic einbr}'o. Afler a short interval, the meintmit! 
is gathere<l into a fold on each side of the primitive trace, and tbesn; fi>Id^, 
advancing toward each other, constitute tlie dorsal lauiinu;^ whicli, when 
fheir edges have met am! coalesced, fonn a tubular cavity — a i 
preparation for the vertebral column. Beneath the tube so ;.,w...^ ^„. 
be discovered, at this stage, a line of nucleated cells — the chorda dorsaJis. 
As the edges of the dorscd lamina^ approach each other, they aasanic a wavr 
tbrm, and simnltancouKly a bending forward or curvature of the embiyo 
occurs, so that the vertebral tube becomes arched. In tlie middle van 
portion are now to be seen rectangular plates, the elements of the fatiuc 
vertebrae The coalcsccnco of llic middle part of the dorsal lamtoit 
takes place first, the ends as yet diverging in the portions which corre- 
spond respectively to the head and tlie sacrum. The spinal marrow toil 
the brain tlius arise at the primitive trace, the brain being a superposed 
or additional structure to the spinal marrow ; for now tlic wavy edges of 
the anterior extiiemity are gradually seen to give origin to three ceils hj 
their juxtaiMwition : 1st. The ei>enccphalon, a single cell, to produce the 
medulla oblongata : its caWty is to be the fourth ventricle ; 2tL The meg- 
enceplialon, also a single cell, for the corpora quadrigcmina : its cavity 
is to bo t!ie ventricle of Sylvius ; 3d. The dcutcnccphalou, a single celL 
for the optic thalami : its cavity is to be the third ventricle. Thougli at 
fir.Ht transparent and fluid, the nervous matter becomes by degrees more 
consistent and covered over with a thin layer of membrane, the indica- 
tion of its future investitures. The rudiment of an eye, under the form 
of a protrusion, now appears from the most anterior cell ; and in like 
manner the auditory apparatus emerges from the cell of the medulla ob- 
longati, frani tlic anterior part of which, by the coalescence of a pair of 
fasciculi which have arisen, tlic cerebellum begins to form* At this peri- 
od, through the continued ciurvaturo of the embryo, the cell of the <X}t- 
pora quadrigemina has become most anterior. 



DBVELOPSreXT OF THE CEREBttOSriN-AL ATiJS, 



293 



The origin of the spinal cord and brain is illustrated in tlic annexed 
figures from BiscIiofT. /Vy. 136 shows upon a dark ground 
a portion of the gcnninal membrane, in tlic midst of which is »['in<ti<«niaii>i 
the area pellncida and primitive trace: tz, the area pellacida; ^* ''"'°' 
i, the dorsal laminte ; t\ the pnmitive trace. 



«r. 15«. 



Fif/. 13T. 



■' ^ 



Tbt pnmiUre inct, xaMeu\tc4 i ditiaicicn. 




OhgiD of ibe bnlu uyvu tlir ipitikl card, nik^ldod 
S iliAiuclrrs. 



I^. 137, tlic same at a later stag;e, preparation for the brain .being 
made The dorsal lamina* arc approaching each other, particularly to- 
ward the middle : «, the dilated upper extremity or cephalic end, the 
throe cells appearing : the epencephalon, mesenceplialon, and deutcnceph- 
alon ; i, chorda dorsalis along the bottom of the groove ; c, rudiments of 
vcrtcbne ; (/, lancet-shaped dilatation. In both figures the pale borders 
along the primitive trace are pellucid nenc substance. 

The dorsal cord, which is only a transitory structure, now disappears, 
the spinal marrow commencing to cxliibit a division into four strands, 
right and left, upjwr and under. Tlic medulla oblongata tiattena nest 
in its upper part, its fasciculi parting from each other; the interval so 
arising betivecn them is to be the fourtli ventricle. The hemispheres 
now appear as a double cell, the prosenccplialon, and as development goes 
on, tliey soon exceed the corpora qiindrigemina in siae, and, as they ad- 
vance, force these bodies backwnrd and under them. 

From this it appears that the t}-jie of construction of the nervous sys- 
tem is, tliat upon the rudimentary Fpinal marrow a scries of vesicles is 
de%'e]opcd. They constitute eventually the medulla oblongata, the cer- 
ebellum, the corpora quadrlgcmina, the thalanii optici, the corpora striata, 

■ the oliactive ganglia, and in front of all, but destined to co%'cr the anterior 

I portions over, the hemispheres. 

I Turning now to the animal scries^ wc iind in the lowest members of 



I 
I 



294 



THE 8PXKAL COBD. 



_ ,. the vcrleLrntn, as in the amphioxus. the Bn'inal cor<l, meJulia 

ucninwiyniem oblougata, auJ, the clcmentnry rcprcsenlalives of tlio scii^rj' 
inTtrtflbmtefc gmiglja alone, and as, in Bucocssion, vc pass to the bigba 
ones. ■we. recognize a cerebclluiu upi^earing over tlie medulla ohlongiila, 
and cerebral hemispheres over tiie sensory ganglia. Tiiese ofgaiu in 
the upward career become more and more devcloi>cd, the hcroispberes, for 
example, soon c«[ualing in size the quadrigemtna, and then greatly mr- 
passing them, and with this increase of size a highcx gnuic of intclligeacc 
is reached. In fishe» tliere are foar ganglia, corresponding rcapcctivdv 
to the cerebellum, qwndrigemina, cerebral hemispheres, and olfactiw gau- 
^dia. In reptiles the number of ganglia and tiieir order of occurrence is 
the same, but the cerebral hemispliL-rcs liavc novr greatly Increased, an 
inereaae wliich is even better marked in birds, for in them the hem- 
ispheres have expanded in front so ns to cover the olfactive ganglia^ aitd 
])OBtoriorly the optic, a condition of tilings analogous to that present^ 
by the Imman brain at about the close of the third month of fa*tal Ufe, 
and approaching tliat pennancntly exhibited by the lower manimiiU,A&, 
for instance, the marsupials. It Is to be understood tliat what is hen 
spoken of as the hemispheres answers in reality only to the anterior lok 
of the ecrebrnm of man; and as in him,diiring the fourth and fifth months 
the middle lobes arc developed in the upward and backward direetior 
from tlic anterior, and still later the posterior lobes from the pOBteiior of 
these, the same coarse is followed in the animal series, the final type of 
development, the trilobed cerebrum, being oidy reached by the highest 
eamivora and quadrumanous animals. 

Comracocing now more particularly with human nervous anatomy— 

STRUCTTRE OF TOE SPIKAL CORD. 

The spinal cord is placed in the midst of the vertebral canal. In fonn 
Docription nf it is cyliudroid, its section being elliptical, the lateral diazne- 
tbo»pitMlcorfi. ter )^j„g tijg lo^ one Longitudinally it shows two en- 
largements, one alxiut its npper third, the other toward its terminatioa, 
Kxteriorly it is white, but its section shows a gray substance, arranged 
in tho form of two crescents connected by an isthmus. Above, it is con- 
tinuous with the brain, wbicli, indeed, is n development upon it, and be- 
low it tcrniinales ut the cauda ef]uina. Its rektivc Icngtlx is much great- 
er in fu-lal life, at the tliird month of which it extends into the sacrum. 
In atlult life it only occupies al)out tlie upper two thirds of the verlc- 
Imd connl ; it is generally stated that its termination is about the first 
or second lumbar vertebra. 3Iorcover, it docs not fill the vertebral ca- 
nal, being, by reason of the transverse dimensions of ll»at cavity, rather 
suspended iu than confined by it. The rest of the space, amount- 
ing to about one tliird, is occupied by the roots of tlic nerves, liga- 



J 




THE STOTAL COHD. 



295 



iV.i«. 




iplaKlaoid. 



turn 



Fio- 120. 



mcnts* tbc investitures of the cord, btoad-veeseU, and a 
liquid. 

J'^iy, 138, A» A, shows the front \*iew of the spinal 
cord, Tvith the mcdalla oblongata; B, B, the posterior 
view ; and C, C, the decussation of its strands, fivm 
which it appears that the organ is composed of two equi- 
lateral portions. They are united by an interior com- 
missure, but sejjarated in front by the anterior, and be- 
hind by the posterior fissure. Of these tJic posterior 
fissure is the deeper, the anterior being wider. Besides 
these regional divisions, the cord also presents longi- 
tudinal fuiTOWs, two for each side, dividing it into the 
anterior, the middle or lateral, and posterior columns or 
tracts, as sJiown in tlie figures. 

With resi^ect to the interior constitution of the cord, 
ii has already been stated that it is composed exteriorly 
of white, and interiorly of gray material. The relative 
quantities of these, and the particiUar form and distribu- 
of the gray substance, may, perhaps, be best understood from the 

sections given in Ju^, 139, 
from one to nineteen, 1 show- 
ing a transverse section as 
high as the cerebral pedun- 
cles* ; 2, through tlie nieduila 
oblongata; and the remaining 
figures, to 19, at lower and 
lower points. 

In tlie first of these sec- 
tions, 1 is the intcrpedoncu- 
lar space ; 2, 2, inferior tract ; 
3, 3, middle tract ; 4, 4, locus 
niger ; 5, 5, superior tract ; 6, 
section of the oqueduct of 
Sylvius; 7, 7, section of the 
superior peduncles of the cer- 
ebellum ; 8, 8, section of the 
two tubercula qtiadrigemina. 
In the second section: 1,1, 
tlie p)Tamidal bodies; 2, 2, 
olivary boiUcs ; 3, 3, rcsti- 
4, 4, section of middle strands ; 6, floor of fourth ventricle, 
the fourth of these sections: 1, the right half of the cord ; 2, left 
3, anterior median fissure j 4, posterior median fissure; 5, 5, pos- 




296 



ersCCTt'EE OF THE BriKAL CORD. 



tenor furrows : 6, while or nntcrior conunusnre ; 7, gray or poeteiior 
coinmisauic ; 8, anterior horn of right crescent; 9, posterior horn of dit- 
to: it U prolonged to the posterior furrow ; 10, antcro-tatcral coltuma: 
11,11, posterior colnmns: these are nil of white tubular substance. The 
symmetrical reference numbers on one side are omitted for the aoke of 
clearness. 

The Bpinal cord is surrounded by three membranes, continuous with 
Urmbnnci of those of thc cnuiiiim : the dura mater, the arachnoid, and the 
ihoi^iDalconl. pj^ niatcr. Thc latter embraces thc cord so closely as to ex- 
ert a compression upon it. This is shown on slightly woondiug it,iHieD 
the white substance protrudes through thc orifice- >vj4a 

Fig. 140: 1, spinal dura mater laid open and drawn 
aside ; 2, 2, sheaths formed by this membrane round 
thc roots and spinal ^j^in^lia; 3, spinal arachnoid; 
4^ 4, sheaths formed by the arachnoid around the 
roots of the nerves and dentatcd ligament ; 5, 5, points 
of communication of the visceral hivcr of the aracli- 
noidf with its |iariotal layer; 6, pia mater; 7, denta- 
ted ligament scparnting tlie anterior roots from the 
posterior roots of thc spinal nerves, and sending as a 
communication between thc dura muter and pia roater. 

From the spinal cord there arise thirty-one pairs 
TtMtplnal of nerves, each nenc having two roots, an 
Dima. anterior or motor, and a jwsterior or sensory. 

The anterior roots issue from the anterior furrow, 
Rmu of the the posterior from the posterior furrow, 
spinal nenej. '^-Iiere the gray substance eniergos. Of 
the two the latter are the larger, and have more radicles. They abo 
have, in the interv-ertebral foramen, a ganglion. JSeyond llie ganglion ibo 
two roots coalesce, and tlie rcsidting nerve trunk, passing through the 
intervertebral foramen, divides into an anterior and posterior branch* for 
the anterior and posterior portions of the body. To this general descrip- 
tion there are, however, some exceptions. Tlius tlie posterior root of tin 
first cervical nerve is smaller tfian thc anterior, and very often it has nO 
ganglion. Thc spinal nerves arc enumerated as eight cervical, twelve 
dorsal, five lumbar, and six sacral pairs. Thc ccn'ical pass off to theit 
distribution transversely, the dorsal obliquely, and the lumbar and sacral 
vertically. Tlie latter constitnte the canda equina. 

Fig, 141 illostrates the origin of the anterior roots of the 8pin«I 
nervesL 1, pons varolii; 2, large and small root of the fifth pair; 3* 
sixth pair; 4, facial nerve; 5, auditory nerve; 6> intermcdian ncmj; 
7, glosso-pharyngeal ; 8, pneumogastric ; 9, spinal acceasory ; 10. hypo- 
glossal. 




Sf-taal dtin 
open. 



STTRUCTLTIE OP THE BPWAL COftT>. 



997 



142. 



in From 11 to 11, the eight anterior roots of the cer\*icol 

nerves; I'rom 12 downward, ihc game roots of the dorsal 
nerves : those of the lumbar and sacral are not ehown in 
tlie figure. As at 15, are shown the anterior branches of 
the spinal nen-ta ; as at 16, iheir posterior branches; at 
17, spinal ganglia formed on the posterior roots ; 18, ante- 
rior roots cut ; 19, anterior roots cut beyond the ganglion ; 
20, dcntated ligament, separating anterior from posterior 
roots; 21, insertion of this ligament on dura mater by ila 
dentated edge; 22, insertion of same ligament on the pta 
mater. 

J^iff, 142 iUnstratcs the origin of the jmsterior roots of 
the spinal ncn'cs. 1, tubcrcula quadrigeniina ; 2, trian- 
gular band; 3, 3, superior jicdundes of the cerebellum; 
4, 4, middle peduncles of cerebellum ; 5, 5, inferior pedun- 
cles of cerebellum ; 6, anterior wall of fourth ventricle; 7, 
glosso-pharjnigeal ; 8, pncumogastric ; 9, spinal accessory; 
from 10 to 10, posterior roots of eight cervical pairs: the 
dorsal, the lumbar, and tlie sacrul below 11 arc not shown 
in the figuR'. From 14 dowiiward, a dotted line arising 
from the tearing aivny of the posterior roots; 15, 15, an- 
terior roots of spinal nerves, the dentated ligament being 
visible througli the removal of the posterior roots ; 16, spi- 
nal ganglia, of wliich there are thirty pairs, the first pair 
of nerves not being frirni»hed with them ; 17, 17, anterior 
branches of spina) nrn'cs; 18, 18, posterior branches; 
19, 19, dentated ligamejit, placed between the posterior 
and anterior roots; 20, same ligament brought into \*iew. 

T^iy. 143 sliowB a portion of the spinal cord j?^. uj. 
surrounded ])y its envelopes, and seen in pro- 
file, so as to display at once the origin of the 
anterior and |K>8terior roots, 1, 1, posterior 
spinal nerves and their ganglia ; 2, 2, anterior roots 
same ner\'C3 anastomosing with the anterior portions 
Be ganglia; 3, 4, anterior and posterior roots cut; 
Eafcd ligament ; C, dura mater, presen'cd to show the 
9 which it forms around these ganglia and the branches 
spinal ner>-cs ; 7, vertical section of the sheath of the 
r and posterior roots, to show the little lamella which 
m tbo one root from the other ; 8, 8, interior face of 

ti mater, which is drawn aside to show the smooth SSIli'',^ 
hich it possesses, owing to the parietal layer of the '*"'***^ 
Bid which covers it. 




398 LONGITUDINAL TRA!?SMISSION IX THE CORD. 

The wliitc or fibrous portion of the spinal cord i* composed in part of 
the spinal iicrrc librcs and in part of oommisaura) ones. At one time it 
waa supposed Uwit eveiy one of tlje preceding continued uninterruptedljr 
to the braiu. On this jwinl, however, the weight of evidLncc will lead 
UB to intiiir that the vertical distance through which the-<ic dlirus para is 
ii<4 very great, and that they arc soon btY)ught in connection with the 
interior vesicular Bubstancc. If all the fibrcs passed uninterruptedly to 
tlie brain, we should expect that the cord would increase in thickness by a 
regular progression upward ; but this, as is shown in Jug. 13S. is not tin 
case. lis enlargcraents correspond to the number of nerve roota ^ven 
off from the localities in which they occur. Thus, where many d«vq 
roots are required for the upper extremities, and again for the lower ooes, 
we notice such corresponding enlargements. The experiments of Volk- 
maim show that these dilatations are as much owing to an increase of 
the vesicular material as to an increased number of (ibros. In the view 
presented in the preceding cha]>tcr respecting nen-e-orcs and the functioni 
of nerve-cells, wc eliouid be Jed to infer that every centrifugal and cen- 
tripetal librc of the cord is brought in connection with such a cell of the 
gray material, and tluit it doea not extend very far from its point of exit 
or entrance. 

KiNCTiciNK or THE Si'lN'AL CoHD. — The dctcTniination of tlio fore;- 
Funriton* or tions of the roots of the spinal nerves by Bell has alrcadjr 
ii)os|iia«l(<ura. (j^,j referred to as one of the great discoveries of physioi* 
ogy, nnd as furnishing a solid foundation for an exact knowledge of the 
functions of the ner^'ous system. The evidence of the trutli of the doc- 
trine that the anterior roots of these nerves ore motor and tin*, posterior 
Bet!'* fill- sensor)', is complete. Thus, if the anterior root of one of the« 
^'t*^- nerves be divided, all those parts winch are supplied by that 
nen'c will exhibit loss of motion, thougli their sensation is unimj>airod; 
if the posterior root be divided, tlic sensibility of tiic parts is lost, though 
the power of motion is unaffected. Similar evidence may also bo ob- 
tained by in-italing the ends of the diWdcd roots, muscukr motion Of 
jKuii, as tlic case may be, being correspondingly observed. 

The spinal cord transmits impressions from the periphery to the brain, 
Lonritniii 1 ^"^ convcrsclv cnablcs the brain to bring into action the 
truuuiwioa of motor nerves. Division of it at once causes an interraptios 
'***■ of voluntary motion and sensation in those parts supplied 
by nerves below the place of the oix>ration. the functions of the piurU 
above remaining unimpaired. But, though the innuence of the brain io 
exciting voluntary motion, and its capability of receiving sensations, la 
thus cut off, the severed portion of tlie cord still possesses an automatic 
power. 

Tills transmission of influences upward or do^mward i^ doubtless, to 



J 



TRAXaVEBSE TRANBMIRSIOX. 



const dcraljlc tlegrec, accomplished tiirougli llie vesicular substance, the 
nUity ol* wiiicli, in this respect, has been explained in the preceding 
pq)tcr. But, besides tliis, the exterior librotis structures {possess a like 
pction, correspondingly as they are connected with tho motor or scn- 
vy roots of tho nerves, tlic anterior columns being motor, and tlie pos- 
rior apparently sensory. 

I The spinal cord not only i>crmits tlic passage of infiucnces in its lungi- 
idinal, bat also in its transverse direction. This is what Tmnirprwi 
Ight bo anticipated Ironi the structure and functions of the irtnuiuwionof 
ila of its gray interior. Il'thc cord bo cut half through in " "*"*=""• 
given place, and again be cut half tlirougii on the opposite side, at a 
ic distance above or Wlow, impressions may be conducted through 
iutcnnodiatc portion, tlio vcslcultur material being tlien. tlielr only 
id. 

In a mcmoix on the dialribntion of tho fibres of tlie sensitive roots, and 

tiw transmission of impressions in tho spinal cord, Dr. Brown-Scquanl 

— i-Scquard, referring to the two theories entertained at wi tbo eouiimv 

t — 1st. That sensitive impressions reaching the cord '"""* «««*. 

in totality to the brain along the postciior columns; 2d. That such 

iona 50 arriving pass directly to the central gi'ay substance, which 

its them upward— otters reasons for supposing that both these 

Koriea, and cajtecially tho iirst, arc contradicted by facts. 

It is his opinion that sensitive impressions reaching the cord pass in 

Iflcrcnt directions, some ascending, others descending, but both going in 

nt by the posterior columns, and in part by the posterior gray horns, 

Bd perhaps by the lateral columns, to penetrate, after a short distoncOf 

! gray central substanco by which, or in which, ihey arc transmitted 

tho brain. 

He also shows tliat sensitive impressions of one lateral half of the 
aro transmitted principally in a crossed manner, that is to say. thnt 
feUow more particularly tho opposite linlt' of the cord to reach the 
irf; that the decussation of the conducting elements for sensitive ini- 
ions is not made^ as is commonly said, at the anterior extremity of 
pons ; that the gray substance does not ]X)ssess the property of 
roitling sensitive impressions in every direction, as some have sup- 
; that most, if not all the conducting dements for sensitive im- 
ious decussate in tho spinal cord, the decussation occurring in part 
immediately on their entry into the cord, but that a few make 
if decussation at a certain distance above the \yo\nt of entry, the ma- 
irity, however, descending in the cord, and making their decussation 
the point of entry ; that if there arc conductiiig elements for sen- 
ivc impressions which ascend tluDUghout the entire length of the coid 
make their decussation in tbe brain, their number modt be very small ; 



300 



REFLEX ACTION. 



and tlmt alterations capable of prodncinp; a panlyais o( eensibilitT, and 
situated ujH>ii any point of a lateral half of the cerebro-8pm.il axis« al- 
ways produce a paralysis of sensibility on the opposite half oi* the bodjr, 
and that there is no difference between the brain and the spinal manov 
in this reajjcct. 

Thus constructed, the spinal cord, as we shall presently show from 
A ii'- ith !'**• Carpenter, evidently agrees with the g&nprliatcd ■v'entnJ 
ventral corU cohI of tlic articulata, each portion of it from wiiicU a pair of 
' ""^ '^" ncr^'es is given off representing each ganglion of that vcntnl 
conU the difference in the two structures being, that in tiie spinal col- 
umn the ganglia arc comuiissured* bo as to form, in appearance, one con- 
tinuous mass, and ngrcejibly to this view of its construction ate tlw 
circumstances uTider winch its enlargements occur. In thooo animal 
fonns in which the entire trunk is conccrnctl in locomotion, as in snakes 
and eels, the cord Is nearly cylindrical ; but as soon as special merobcn 
for locomotion arc developed, a corresponding increase of diameter is ob- 
served. Thus, in birds, the ganglionic enlargement corresponds with tli< 
region from which the nencs for tlic wings are given off; Imt in that tribe, 
as in the ostrich, tlie mode of locomotion of whicli is by tho logs tather 
than by tlie wings, a corrcsjtonding posterior enlargement occurs. Ti» 
same ob3cr\'alion3 may even be morc distinctly made during metamorplh 
ose.i; thus, in frogs, wliilc they are ui tlie tad])ole state tlie spinal cordis 
cylindrical, but bulging ensues in it anteriorly ami poi-teriorly as aoon u 
the anterior and [wsterior membera are derelopciL 

The translation of impressions wliich have been bronght along tlie 
KcfloMctton cejitripetal fibres into motions, the exciting influence of which 
of ihe torii. ia conveyed along the centrllugal tibrcs. includes what is niv 
dcrstood as the reflex action of the spinal cord as dr^veloped by Dr. Hill 
Its essential condition is its indc|>cndcncc of the agency of tlic brain, and 
therefore unconscious nature. As general esamph»s may lie meniioncd 
the movements which occur in swallowing; for after the food has been 
carried by voluntary action into the fauces, its posaage onward ti) llie 
stomach is perfectly involuntary. In like manner, the introduction of air 
into the hmgs in ordinary respiration is involuntary ; for though it may 
be, to a certain extent, under tlw. control of the will, yet that c.^ct^nt is 
limited, n necessity for the motion j>resently arismg, which soon becomes 
uncontrollable. The action of the valvular arrangements at the car^ae 
and pyloric orifices of the stomach, and the constant contraction of the 
sphincter ani, are farther illustrations. To these may lie added those 
impulsive movements which we instinctively make on the approach of 
danger or in the act of falling, and perhaps, too, automatic walking, as 
we go from place to place in a state of mental abstraction, paying no at- 
tention to tlie course wc take. 



EEFLEX ACnOX. 



301 



k 



Flff. 144. 



The cord is to be regarded as a longitudinal scries of simple automatic 

I nerve arcs, or, as we have termed it, a multiple automatic Aaioroaiic »r- 

I arc. f^icli flcgiueut of it lias therefore an independent action tioaoftheconl. 

of ita own, but can conspire with its neighbors or be influenced by the 

brain, by means of its commissural 
fibres, an arrangement of whicli num- 
berless interesting instances might be 
furnished. Tlic one rcprej>cnted in 
/7^. 144, which is from the cord of 
Bpirostreptns, may, however, suffice : 
A, under surface of n portion ; B, u|>- 
per surface ; «, inferior longitudinal 
fibres; e, superior longitudinal tibrcs; 
f^ fibres of re-cnforccmcnt, seen also 
at b and c; ^, commissural Hbrcs, seen 
also at d. 

The power which the cord displays 
in this simple action is most striking- 
ly seen when it ia cat off from ita 
cranial connections. The decapitated 
frog props himself up stiffly on his 
legs, and, if his cutaneous surface be 
portiottofeordorfpiroftropttu. irritated, exhibits antagonizing mo- 

tions; sucli motions are all of the rcdex character, and arc commonly 
much more strikingly seen in cold than in warm-blooded animals; but 
erea in man precisely the same results arc witnessed during periods of 
the aoflpcnsion of the actiWty of the brain, as, when tire palm of the hand 
of a sleeping child is touched with the finger, the finger is at once grasped. 
As above stated, this reflex function of the cord is therefore independ- 
ent of the brain, though the brain can control it, and this ^^^^^^ ^^(^ 
the more perfectly the higher the organization of the animaL Jndppf-iideutor 
Breatliing can go on, whether we pay attention to it or not, ™"** 
bat we can arrest it if we choose for a time ; and since in man (his in- 
troduction of air is incidentally used for very refined purposes, by volun- 
tary exertion we moderate or regulate it, as in the production of musical 
sounds in singing or of articulate sounds in speech. 

In a general way, there is not much difficulty in distinguisliing be- 
tween simple actions of the cord and those in which the brain Dudnctioa b»> 
ia participating. In the former, no weariness or fatigue is inJ^J^J^J^j 
ever experienced ; in the latter it is ; and perhaps, even in «ct«m. 
these last, invoU*ing voluntary muscular action, though tlie control is to 
be attributed to the brain, the source of the force is in the cord. 

These normal phenomena which the cord displays become ^rcatly ^2> 




* 

i 
k 



802 KELATTON^^TO^PraAL COItD AXD BRAIV. 

Iaei««Kof njrgiTatcd in certain conditions of disease, as, for pxaniplc 
■pioai Action, tetaimg^ i„ uhicli the slightest peripheral irritation may W 
followed hy violent conMilsivc movement, or Ui© same occurs l»v llie 
agency of powerful poisonous substances, as stn'chnine. In llicdc cases 
the action may be eitlier limited simply to the cord, as in the tctaau 
brought on by opium in frogs, or the brain may be involved in it, «s is 
cases of hydrophobia, in which the sound or sight of water, opcntii^ 
through the cerebrum, will produce spasmodic convulsions. 

From the (iicla presented by the lower anima]<x, it may Ijc inferred that 
the spinal cord does not act as a single organ, but ratlier ahould be to- 
gnnleil as a collection of ganglia, special duties being diacliargcd by ?p^ 
cial ]>arts of it. 

With respect to the commissural action of the spinal conl, reference has 
- .. , already been made to the stnictural connection between tHa 

Conaocliott of 

tho coni «iiJ cord and the nervous regions above it, and in referring to ll» 
old anatomical doctrine tlmt each of the spinal nerves is coo- 
nocted by continuous fibres with the brain, due weight has l»cen girra 
to the fact tliat the cord does not increase in tliickness as it approaches 
the brain, but that its bulginga correspond to the regions from which it is 
necessary that an iinusual supply of nrrws sliould be given off. The 
(brce of this argument is, however, considerably diminished when ire 
recollect that the nerve-tubes are by no means of uniform diameter, bnt 
arc doubly conical in sJiaiie. Even, therefore, with a diminished diame- 
ter of the spinal cord, there might bo an upward cont'muation of sp'uul 
fibres, the diameter of which is becoming less and less ; and this scents 
to lie rendered more likely from the analogy of the structure of the veih 
tral cord of the articulata, in which tjlirea lu^ sent to the cephalic gaih 
glia for the purpose of establishing a communication between them atMl 
the roots of the nerve?. Hnt, however that may be, there can be no 
question of the influence of the brain over spinal action, and this, of eonra^ 
implies structural connection of some kind — an intercommunication — 
which, if it docs not take place solely through the white columns, must 
take place through the gray material. It is, however, important to ob- 
serve that the gray material has no direct communication with tliat of 
the cerebrum, but, passing through the optic thalamus, ends in the cor^ 
]ius striatum, extending therefore in one continued mass through the cord, 
and terminating in that ganghonie organ. Tiy one or both of tliese chan- 
nels, white or gray, the impressions which are made upon the spinal 
sensitive nerves are presented to the brain, and in a similar manner the 
intlucnccs which produce voluntary motions arc transmitted down. A 

., section of anvpart of the spinal cord at oneo incapacitates the 
Effect of 16- , ^ - * , ' , , - . ..1-1. 

sionaofthe wul from acting upon tlie parts beyond, tlie motions ol which 

"*"*• becomo therefore purely automatic, though the parts above still 




rUNCTTONS OP THE SPINAL COIID. 



303 



tisplay tlieir customary phenomena. These effects ore somclimea in- 
itnictively witnessed in man when lesions of tiie cord have occurred 
throngb disease. 

I 11* the view that has heen pi-escnted respecting tho continuation of 
nbrc3 from the cord to tho LraJn bo correct, iIicac tibrcs dis- ,, . 

Alotor Ant] aon* 

charge a commissural duty. This would lead ua to sup- K>ry uicu of 
pose that there is a correspondence between the functions of '*** ""^ 
the columns of the cord and those of the roots of the spinal nerves, tlic 
anterior columns being motiferous, or in unison willi tlie motor root of 
Hie ner\ea, tho posterior being scnsifcrous, or in unison with the sensory 
root of the nerves. Agrocjdtly to this, if the anterior columns be irri- 
tated, motions arc excited in ull thoi=c parts which arc supplied with 
pervc» beyond the irritated pohit ; and if the posterior columns be irri- 
hoted, in like manner pain is experiencal. In this instance, however, a 
certain amount of motion is occasionally obscn*ed, but this lias common- 
f been explained by referring it to refiexion within the cord. It has 
klso been obscr\'cd, aa strengthening these views, that if tho posterior 
p>1anui3 be irritated after complete section of the cord, the result will de- 
pend on wliich of the cut portions be disturbed ; if it be the lower, there 
will be no effect. An examination, under the same circumstances, of the 
Ulterior columns, demonstrates that, if the uppci' section be irritated, there 
is no effect produced ; if the lower, there are conviUsive movements of 
he parts supplied with nerves beyond. 

From these results wc should infer that the pliysiological functions of 
the anterior and posterior roots of the spinal nerves arc participated in 
by the anterior and posterior colunuis of the cord, and might tLeiefore 
expect tliat those functions would be continued in the higlicr distribu- 
tion of the columns above the medulla oblongata. 

From the point of riew under which we have thus presented it, the 
fection of the spinal cord is tliereforc simple, or it is disturb- Ronrr*! funo- 
cd by the agency of the brain; in the tirst ease it offera il- t'««» "ftiw 
pelf purely as an automatic instrument ; iu tlie latter, its com- 
l&issund connections with the brain make a compound apparatus. The 
former state is closely represented in tho construction of the anijdiioxns, 
the nervous system of which has no rudiment of a cerebrum or cerebel- 
lum; in thU animal, therefore, since also the sensory ganglia are merely 
in a rudimentary state, the mode of lite must be jnirely nuxhauical, just 
is it is with an artificial automaton, of whicli, when a given spring is 
touched, a given motion is made. Even among the highest vcrtcbrated 
animals, man himself at the periodic times of <iuiescence of the cerebrum, 
Is in sleep, when the cerebral influence over other portions is, to a certain 
Bxtent, suspended, an approach to a similar condition occurs ; hut in 
icriods of actiuty of the cerebrum, it can hold the spinal cord in check, 



004 



THE MEDULLA OBLONGATA- 



oonfTolling, and in some cases arresting im action^ and tliis is donctliroogH 
influence--? propagated along the tabular atructurca of the posterior and tat- 
tenor colunma, whicli therefore are to he regarded, in tliii respect, is 
comroissures to the train. 



OF THE MEDULLA OBLONGATA. 



The 



incdalla oblongata U 
and the brain. 



a conical body, Iring between the spinjil cord 
Limits of the *""* "^"^ «•«•". It 18 generally understood to bo boiindedat 
BirduUauUion- its uppcr portion by tho pons varolii, but thia ia not a titie 
^^^ limit, since its structure extends through tho pons varolii to 

the crura of the brain. There is the same indcfinilencss of limit as re- 
spects its lower boundary, which is generally said to bo marked by some 
decussating tibres which appear on its fronL Like the spinal cord, it 
III BuiKiivi*. has an anterior and posterior fissure, which divide it into two 
**"**• symmetricid lateral halves ; the former is a continuation of 

the anterior spinal Hssurc, the latter of the posterior, and ends in the o- 
lomus scriptorius above. The lateral halves thus produced are marked 
by three grooves, producing four eminences, which pass under the foUoa- 
ing name^: 1st. The anterior pyramids; 2d. The olivary bodies; Sd. 
Tlio restiform bodies ; 4th. The jwsterior pyramid*. The anterior fa- 
Burc is crossed about an inch below the pons varolii by decussating tibres, 
and hence injuries on one side of the brain produce nervous effects on tho 
op]>osite side of tlio liody. 

HraL Tho anterior pyramids consist of white 6bres originating near 
Tii* •Dtfrior ^^>® decussating fasciculi. They have a compound structure, 
pjTtmiiii. fof (jach contains fibres arising from tho inner side of tlie op- 
posite anterior column of the conl, and also 6brcs from its own side: 
tlicy pass through the pons varolii into the cms cerebri. From thoee 
pjTamids curved tibrea pass round the olivary body, and arc lost in tiie 
rostiform. They are calle<l arciform tibres. 

Second. The corpora olivaria receive their name from their olive shap& 
Tlw oUviry They are separated by a groove from the preceding in fronl, 
'™"«»' and by another groove from the restiform bodies behind. £i- 

temally, they arc formed of white tubular tissue, which incloses a Teac- 
ular mass, the olivary ganglion, wliich connects with the vesicular struc- 
ture of the pons above, and that of tho cord below. The fibres of these 
ganglia are called tho olivarj' tracts. They are continuous with the cen- 
tral part of the medulla oblongata, passing behind the pyramids, extend- 
ing upward along tlie posterior part of the crura cerebri to the optic thai- 
Ami and tubcrcula quadrigemina. The olivary bodies exist only in man 
and tlie monkey tribe. 

Third. The restiform bodies are se])arated from the olivary by a 
groove. They are continuoua witli the posterior and anteio-lateral col- 



M 



THE MEDULLA ODLOXOATA. 



aofi 



ans of llie cord. Ascending, they enter the ccrebcllnm, and 11,^ re»ur«rn 
continuous with liic inner part of ita cru3. They tkcre- '«'*i'"- 
fore arc a tract of communication from the spinal cord to tlie cerebellum. 

Fey each inclose a gray nucleus, which is the ganglion of the pncumo- 
rtric nerves, and of some of the roots of the glosso-pharynge^l. 
Fourth. The posterior pyramids are doubtftUIy marked off from the 
Tcstiform bodies in front, and arc separated from each other Tbojiostmor 
by the posterior iissurc. Superiorly, their fibrea are contin- prriwid* 
aons witii the sensory tract of the crura cerebri : their gray nuclei arc 
the ganglia of the auditory nerves. 

j^. 145. The structure of the medulla oblongata is exempli- 

fied in the annexed figures. 

iTy. 145 : 1 , chiasm of the optic nerves ; 2, cms cere- 
bri; y, tuber cincrcum; 4, cor|K)ra albicantia ; 5, locus 
pcrforatus ; 6, pons varolii ; 7, section of the middle 
(>edunele of cerebellum ; 8, transverse Bssurc, separa- 
ting the medulla from the pons; 9, iirst enlargement 
of the cord, or medulla oblongata; 10, anterior p>Ta- 
mid; 11, ohvary body; 12, anterior portion of reali- 
form body ; 13, neck of tlic medulla oblongata; firom 
IG downward is the anterior median tissure; frora 17 
downward, the anterior lateral furrow. 

I^iff. 14G: 1, section of optic 
tract; 2, rubercula quadrigcmina ; 
3, triangular band ; 4, section of cms ccrebctli ; 5, 
medulla oblongata ; 0, anterior floor of tlie fourth ven- 
tricle ; 7, median fissure of the fourth ventricle, aid- 
ing to form the calamus scriptorius; 8, mammillary 
swelling near the nib of the pen ; 9, posterior portion 
#1^.147. of tlie rcstiform body; from 12 down- 

ward, posterior median tissure ; from 
l.'S downward, lateral furrow; from 14 
•downward, posterior furrow. L,» t 

,,.,._,. , - , Ptirtcrior view of mcaall* 

j'tff.147: 0, anterior column of tuc obhwgAia. 

cord, divided superiorly into two portions, of wiiicli the 
most internal one contributes to the formation of tlio cor- 
responding p}Tamid ; 7, middle or lateral column, di- 
vided superiorly into three or four portions, decussating 
with as many portions of the column of the opposite side, 
the decussation taking place both laterally and antero- 
postcriorly: it is the origin of the internal two thirds 
of the pyramid; 8, S, pyramids ; 9, winte iibiTs of the 
dttUa Aoa rona, pyramid, traversing the pons, and continuing to the eras 

u 



Fi^. IW. 



506 



rtv- u& 





Itatelor Tttvornediilta oUongilk. 



THE UEDULLA OBLOXOATA. 

cerebri ; 10, superficial Bcction of the tniu- 
•**ergc fibres of the pons ; 1 1 ^ tlwpcr wctiw 
of the triinaversc fibres of the [>on8; 12,fll»' 
Tary body ; 13, right olivary body, l-r t 'tit 
into view by removal of the corrcsj-iiii.j 
pyramid. 

Fitj. 148 is a posterior view of ihe nic- 
dallft oblongata : y?, /». posterior pyramids, 
BCparated by n posterior lusurc ; r, r, reiti- 
(bnii bodies, composed of, <:, c^ posterior ool- 
umns, and </, </, part of antcro-latcnd oil- 
umna of the cord; a, a, olivary colunins,t3 
seen on the floor of the fourth ventricle, sep- 
arated by «, the median fissure, and crossed 
by some fibres of origin of, nj n, tlic scventli 
pair of nerves. 



FUNCTIONS OF TlIE MEDLXLA OBLONGATA. 

Viewed OB a superposed conlinantton of the spinal cord, the meduJU 
FnnctionK Qf oblongata IS the tract of comnmnicntion between that orgw 
ih« mcduU. : ajj^ thc brain : the anterior pyramids and olivary tracts con- 
cDtnmanlc*- vcy motor infiucnces, and thc restiform tracts and postenor 
''^- pyramids sensations. Hy cxpciriments similar to those wbicfc 

have been performed upon thc cord, theso concloaions have been maifr- 
laincd. 

Bat, besides this function of conduetion, the medulla oblongata di»- 
chargca a most important duty as a nervous centre ; on it depend respi- 
ration and deglutition. The brain may be wholly removed above, and 
the spinal cord below, as for as the origin of thc phrenic nerve, withoiU 
deatli necessarily ensuing, but on wounding the medulla oblongata, the 
muscular movements necessary for the introduction of air arc ncccssaxilr 
slop|>cd. 

ilorcovcr, tlie medulla oblongata exhibits tlie property of rc£ex action. 
lu rQtaUaiu to So for as the function of respiration is concerned^ its diief 
raipiration. ccntripctsl nerAc is the pncumogastric, but thc power whicb 
it possesses is participated iu by :nany others, pcrliaps by reason of ibe 
venous condition into which the blood is brought from want of propet 
aeration. The violent respiratory movements by thc sudden uppUcalion 
of cold to thc skin, tlic shower-bath, or dashing cold water on the fiice, 
nro converted by it into respiratory muscular motions. From it also 
arise the movements required in thc act of de^utition. 

Under this view of the functions of the medulla oblongata, it ia to be 
regarded as au exclusively automatic instrument, which con continue its 



THE rONS VAROtn. 



807 



p 



I 



I 



operation ancr llic excision of the brain. As witli tlic spinal corJ, so 
iritli it: its simple action inay continue though its coninuBSural action 
h$ cea^d, and this cither througli conditions of disease or by the nd- 
JDiaiBtration of drugs. In lesions of the brain respiration may still con- 
(imic, as it may aUo when sensation and voluntary motion have been ar- 
nstcd by the breathing uf clilorofonn. 

OF TUE PONS VABOLIL 

Tbo pona varolii consista of a loop of fibres poAsing from one crus 
ccrebclli to iho other, aronnd the tracts of communication stniciure of ihe 
between tlic conl luid the brain. As sliown in I^tf/, 145, ponavaruiu. 
thcv do not fonn a conlinuoua 8iii>eWicial cotti misiiure, but, at a certain 
distanco below, interlace with the fibres of the pyramids; moreover, 
among their deeper fibres jjray vcsieulnr matter occurs. That tliey con- 
stitute mainly a coniniissuje for the cerebellum is ai>parent from tlie eir- 
cnmatancc that, in those animals which have the median cerebellar lobe 
only, there is no pons, and in other cases its relative magnitude is iu 
proportion to the sizq of the cerebellar hemispheres. 

FUKCnONS OF THE PONS VAROLU. 

The functions of the pons varolii aio lliorefore twofold : it acts as a 
conductor, and also as a nerve centre. In tlie first respect, it puncUoni of 
is the channel from the spinal column to the cerebrum and *'•" i*"""- 
cerebellum, and also between the cerebellar halves, and cxi>enment3 upon 
it, in giv'mg rise to sensations and motions, are in conformity with wliat 
wc should anticipate from the structure and functions of the spinal cord. 

In the aeeond rt*spect, as a nervous centre, it has been stated that, when 
the ccrebram and ccrcbcUmu arc removed, but the pons left untouched, 
u animal gives tokens of sensation when pinched or irritated, and likc- 
wwo executes motions which have an object ; these, however, were no 
lORger observed after the removal of the pons. 

Wo have Imd repeated occasion already to mention that the surest 
.■mide which can Ite followed in iutorijretations of the func- 
tions of the ncr^-ous system is compamtive phynimogj'. ( mr ler'i view» of 
views of the action of the spinal cord, mednlla oblongata, [|^'^"j*,Jf;*J* 
and even portions above, hereafter to be described, will !« nsl cunj ofvfr- 
rcndercd clear by a knowledge of the structure and fnnc- [J^'J^JI^'' 
tiona of the ventml cord of the articulata, the analogy of «iniof«nieo- 
which to the parts wc have had under consideration was "^' 
first correctly pointed out by Dr. Car^ienter. I tlierefore transcribe from 
his General and Compniti\'e Phj-siology the following paragraphs, which 
present his views with perspicuitj-. 

The plan on which the ner\'otis system is distributed in thm wjV 



u 



SOS 



FDKCnONS OF THE CORD. 



Ft% 143. 



X 



king<]oin articulata exhibits a remarknblc uniformitj' tliroughont the 
tvholc aeries, wliile ils character gradually becomes more elevated as ire 
trace it from tlic lowest to the highest divisious of the group. It vsxx- 
ally consists of a double nervous cord studded with ganglia at intcmLs 
and tho more alike the diflcront segments, the more equal are these gau- 
glia. Tlie two tilamenta of tlie nervous cord are sometinies 
at a considerable distance from one anotlier, and the gan^tft 
arc distinct, but more frrqucnlly they arc in close apposition, 
and their ganglia ap|)car single and common to lx»lh- That 
which may seem as tlie typical conformation of tho nervoas 
system of this groap ia seen in tho ganglionic cord of«a>/> 
petulra^ or in that of the larva; of most insectfi, such as tluit 
of tho »phinx liffustrij Fi/f. 149. Here wo see tho ncrvoiu 
cord nearly uniform tliroughoutt its two halves being sepa- 
rated, however, in the anterior portion of the body- TTio 
ganglia arc disposed at tolerably regular intervals, are sinu- 
lar to eacii other in size (with tho exception of tho lut, 
which is formed by the coalescence of two), and c\*cry one 
supplies its own segment, and has little connection with any 
oilier. The two filaments of tlic cord diverge behind tbc 
head to inclose the a'soplmguSf above which we Bod a pair 
of ganglia that receive tho nerves of tlie eyes and antcnDT. 
We shall find that in the higher classes the inequality in tic 
formation and office of the diiFcrcnt segments, and tho in- 
creased powers of spcciiil sensation, iuvolve a cousideiabk 
chuiige iu the nervous system, which is concentrated aboot 
the head and thorax. Iu tlic simplest vennifomi tribes, oo 
the other liand, we lose all trace of separate ganglia, the nervous canl 
passing without evident enlargement from one extremity to the other. 
"Whatever may be tlie degree of niuliiplication of the ganglia of tlw 
trunk, they seem but repetitions of one another, the functions of etch 
segmont being liic same with those of the rest. The cejjAalic gna^v^, 
however, are always larger and more important. They are connected 
witli the organs of special sense, and they evidently possess a power of 
directing and controlling the movementa of tlie entire body, while the 
power of each ganglion of the trunk is confined to its own segment 

" The longitudinal gangUonic cord of the articulata occupies a positioa 
whicli seems ut tirst sight altogether different from that of tho ncrvooB 
system of vertcbrated aniinaU, being found in tho neighborhood of the 
ventral or inferior surface of their bodies, instead of I}nng jiist beneath 
theii- dorsal or upper surface. From the history of their development, 
however, and fixfm Bome other considerations, it has been saggcsted that 
the ic/wl<i body of these auimaU may be considered as iu ou invortod po- 



XrrrouB tyflna 
of Un-ft uf 
Bphlnx ligiuirl. 



rUXCTIOSS OP THE CORD. 



> 



I 



Ihc part in which the scgmcnlation is first dUtinguighed in insects 
iig the equivalent of the dorsal region in vertcbrata, and tliat over 
which the germinal mcinLrane is last to close in:, being homologcius wilh 
tho ventral region. This view applies also to the position of the dorsal 
vessel, which would then be on the ventral side of the axis, as in vcrte- 
biutn. Itcgardcd \mder tliis aspect, the longitudinal nervous tract of ar- 
ticalatA corresponds with the spinal cord of vcrtebrated animals in posi- 
tioHf aa vc shall 6nd it does in function. 

** When the structure of the chain of ganglia is more particularly in- 
quired into, it is found to consist of two distinct tracts, one of wiiich is 
composed of nerve fibres only, and passes backward from the cephalic 
ganglia over tho surface of all the ganglia of the trunk, giving oft* 
branches to the ncr^'es that proceed from them, while the other includes 
the ganglia themselves. Ilence^ as in tlio mollusca, every part of the 
body has two sets of nervous coimections, one witli tho cephalic ganglia, 
and the otlier with tlie ganglion of its own segment. Impressions made 
upon the afferent fibres wliicli proceed from any part of the body to the 
crphalic ganglia become Rennalions when conveyed to tlie latter, while m 
re5.|iondenco to these, tlie consensual impulses, operating through the ce- 
phalic ganglia, harmonize and direct tlie general movements of the body 
by means of the efferent nerves proceeding from them. For the purely 
reflex operations, on tho other hand, the ganglia of the ventral cord are 
sufficient, each one ministering to the actions of its own segment, an J to 
a certain extent, also, to those of otlier segments. It has been ascertained 
by tho careful dissections of Jlr. Newport, to whom we owe all our moat 
accurate knowledge of the ncr\ous system in articulated animals, tlmt of 
tho fibres constituting the roots by which the nerves arc implanlod in 
the ganglia, some pass into the vesicular matter of the gangUon, and, after 
ooming into relation with its vesicular substance, pass out again on the 
same side (/Vy. 150,/", /•), while a second set, after traversing the vesic- 
ular matter, pass out by the trunks proceeding from the opposite side of 
tlw tame ganghon, and a third set mn along the portion of the cord which 

connects tlic ganglia of different BcgmcnlB, 
and enter the nmous trunks that issue from 
them at a distance of one or more ganglia 
above or below. 

"7^/^.160, from ganglionic tract of poly- 
dcsmus maculatus. i, interganglionic cord; 
0, anterior ncncs; </, posterior ; y, X', tibrcs 
of reHex action; ^, A, commissural fibres; j, 
longitudinal fibres, softened and enlarged as 
they pass through the ganglionic matter. 
** Thus it appears that an im^rcauQU CAior 



n$.i»i. 




dio 



PUKCTIOXS OP THE CORIK 



veyed by an aficrciU fibre to any ganglion mar excite motion in the mu- 
clea of the same side of its own segment, or in those of llto opposite iidc 
or in those of segments at a greater or les^ distance, according to ik 
point at which the efferent fibres leave tJie cord ; and as the fiinctioD ot 
llicso guiigUa is altogether related to the locomotive actions of the tn^ 
ments, we may regard them as so many repetitions of the pedal gao^a 
of the uioUuscar tiieir multiplication being iu precise accordance with tbkt 
of the instruments wliich tlicy supply. 

** The general conformation of articulated animals, and the ajrangi 
of the parta of their nervous systems, render them |)eculiarly iavoraUe 
subjects for the study of the reBe^ actions, some of the principal ^ 
nomeua of which will now be described. The mantis religiosa custoiD- 
arily places itself in a curious position, e3])eciiiUy when threatened or al- 
iHcked, resting on its two posterior pairs of legs, and elevating its tlioni 
with the anterior pair, whicli ore armed with powerful claws ; now if tha 
anterior sograent of the thorax, with its attached members, be rcraorecl 
the posterior jxirt of the body will still remain balanced upon the fijur 
legs which belong to it, resisting any attempts to overthrow it, recover- 
ing its position when disturbed, and pertbnuing the same agitated niore- 
nicnts of the wings and elytra as when the unmutllated insect is iiritalcd; 
on the otiicr hand, the detached portion of the thorax, which coQtaioi i 
ganglion, will, when separated from the bead, set in motion its long titas, 
and impress thiiir hooks on the fingers wliich hold it. If the head of » 
centipede be cut oflf while it is in motion, the body will continue to move 
onward by the action of the legs, and the same will take place in the 
separate ports if the body be divided into several cUstinot portions* 
After these actions have come to an end, tliey may be excited again hj 
iiTltating any part of tlio nervous centres, or the cut extremity of the 
nervous cord. The body is moved forward by the regular and sucocssiTe 
action of the legs, as in the natural state, but its movements are alw»ys 
fonvard, never backward, and arc only directed to one side when the for- 
ward movement is checked by an interposed obstacle. Hence, though 
they might seem to indicate consciousness and a guiding will, they do 
not 80 in reality, for they arc carried on, as it were, mechanically, anil 
ahow no direction of object, no avoidance of danger. If the body be op* 
poBcd in its progress by an obstacle of not more than half of its ovn 
hciglit, it mounts over it. and moves directly onward as in its natural 
state ; but if tlio obstacle be equal to its own hciglit, its progress is arrest- 
ed, and the cut cxtreraify of the body remains forced up against the op- 
posing substance, the legs still continuing to move. If, again, the nerv- 
ous cord of a centipede be divided in the middle of tlte trunk, so that the 
hinder legs are cut oif from connection witli the cephalic ganglia, they 
trill continue to move, but not in lionaony wiih those of the fon: part ol" 




FUNCTIONS OP THE CORD. 



311 



<the body, being cornplelely paralyzed, so far h3 the animal's controlling 
power id concerned, tliough still capable of performing reflex movements 
by the influence of their own ganglia, wiiich iniiy thug continue to propel 
the body in opposition to the determinations of tlie animal itself. Tlic 
is still more remarkable when the nervous cord is not merely di- 
rided, but a portion of it is cnlirely removed from tlie middle of the trunk; 
for the anterior legs still remain obedient to the animal's control, the legs 
of the segments from which the nervous cord has been removed arc alto- 
gctbcr motionless, wliilc those of the posterior segments continue to act 
llirough the redex powers of their own ganglia, in a manner wliich shows 
that the animal has no power of checking or directing them. 

'•The stimulus to the reflex movements of tltc legs in the foregoing 
appears to be given by the contact of the extremities witli the solid 
m&ce on which they rest. In other instances the appropriate impression 
can only bo made by the contact of liquid. Thus a dytkcus (a kind of 
nrater-boetlc), having had its cephalic gangUa removed, rcma'mcd motion* 
less SB long as it rested upon a dry surface, but when cast into water tt 

leculed the usual swimming motions with great energy and rapidity, 
■tiiking all its comrades to one side by its violence, and persisting in 
tiiese for more than half an hour. Other movements again may be ex- 
cited ibrongh the respiratory surface. Thus, if the head of a centipede 
be cut off, and, while it remains at rest, some irritating vapor (such as 
that of ammonia or mnnatic acid) be caused to enter the air-tubes on one 
vide of the trunk, the body will be immediately bent in the opposite direc- 
tiont 80 OS to withdraw itself as much ns possible from the inducncc of 
tbe vapor ; if the same irritation be then ajipUcd to the other side, the re- 
Terse movetnent will take place, and the body may be caused to bend in 
two or three different cun-es by bringing the irritating vapor into the 
Bsighborhood of different parts of either side. This movement is evi- 
dently a reflex one, and 8er\e9 to withdraw the entrances of the air-tubes 
from the source of irritation, in tlie same manner aa the acts of cougliing 
imd sneezing in the higher animals cause tlie expulsion from the air-pas- 
Mgea of solid, liquid, or gaseous irritating matters whiclt may Iiave found 
ibeir way into them. 

**From these and simibr tacts, it appears that tlic ordinary movements 
of the legs and wings of articulated animals arc of a reflex nature, and 
onay l>c effected solely througlj the ganglia with which tlieso organs are 
«everaUy connected; while, in the pcrtect being, they arc harmonized, 
controlled, and directed by impulses which act through the cephalic gan- 
glia, and the nerves proceeding from ihcm. There is strong reason to 
^eUevc that the operations to wiiich these ganglia arc subservient are al- 
MMt entirely of a consensual nature, being immediately prompted by 
■cnsations, chiefly those of sight, and seldom or never by any ^ttut^fisu^ 



of a traly rational cluiractor. When Tve attcntivdy consider ihe luUti 
of these animals, we tind tiiat their actions, though cridcntlv directed to 
the altainmejit of certain ends, are very far fron» being of the wune ffon.- 
tancoua nature, or from possessing the same designed adaptation of mean! 
to ends as those performed by onrsclves, or by the more intelligent vci- 
tchrata under like circumstances, \^'c judge of this by their unvarying 
character, the different individiiuls of the same species exocattng pt^ 
ciscly the same uiovcracnts when the eircumatances are the eacne, and 
by tito very elaborate nature of the mental emotions which would be n> 
quired in many instances to arrive at the same results by an effort o( 
reason. .Of such wc can not have n more remarkable example than Is 
to be found in the operations of bees, wasps, and other social insecti^ 
which construct habitations for themselves upon a pUn which the mort 
enlightened human intelligence, working according to the most relued 
gconietricid principles, could not surpass, but which yet do «o without 
education communicated by their parents or progressive attempts of thcv 
own, and with no trace of hesitation, conlusion, or interruption, the di^ 
iVrent individuals of the conmmnity all laboring efledively to one pu^ 
pose, because their automatic impulses (producing wliat are usually term- 
ed instinctive actions) arc all of the same nature, 

** Not only arc the locomotive ganglia multiplied in accordance with tbe 
repetition of segments and members, but the respiratory ganglia arc mul- 
tiplied in like manner in acconlance with a repetition of respiratory at' 
gans. The respiratory division of the ner\"0U3 system consists of a cbian 
of minute ganglia lying upon the larger cord, and sending off its delicate 
ner\*e9 between those that proceed from the ganglia of the latter, as seen 
in 7*7*/. lol. Tlicse respirator^' ganglia and their nerves are best seenia 
tlie thoracic portion of the cord, where tlie cords of communication be- 
tween the pedal ganglia diverge or 8e]>ai-ate from one another; and this 
is particularly the case in the pupa state, when the whole cord is being 
shortened and their divergence is increased. The thoracic jwrtion oftho 
cord is shown ui J'^iff. 152, li, wliich represents the second, third, ana 
fourth double ganfjlia of the ventral cord, the cords of connection between 
tliem here widely diverging laterally, and the small respiratory ganglia 
which are connected with each other by delicate filaments that pass over 
i^. 181. the ganglia of the ventral coni, and which send off lateral 

brandies that are disiribnted to the air-tubes and other 
[l (mrts of the respiratory apparatus, and communicate writh 

those of the otiicr system." 

Illustrations of the nervous system of the articulata. 

/''iff. 161, A, single ganglion of ccntijjed^, much enlarged, 

showing the distinctness of the purely fibi-ous tract, i, from 
«ngiinj>of«ini- ^^^ ganglionic column, a. Fig. 152, B, portion of the 





THE BBAIlf* 



318 



#lff. 1S2. 




<Ioul)Ie cord from ihe thorax of 
the pupn of sphinx llgHShri, 
showiji}^ the respiratory gan- 
glia and ner^'es between tlie 
ganglia 2, 3» 4, and the sepa- 
rated cords of the locomotive 
gyslem. I'lg. 153, C, view 
of the two Bystcnis combined, 
showing their arrangement in 
the lan'ft: o, ganglion of tho 
ventral cord ; i, fibrous tract 
passing over it ; f, f, respira- 
tory system of nerves, distinct 
from both. 

Having thus presented the views of Dr. Carpen- 
ter lespccting the analogy between the ventral cord 
of the articulata and the spinal cord of the verte- 
bmtA, I should next continue tho explanations 
which this physiologist has ofi'ercd of the connec- 
tions and Tclations of the sensory ganglia; but tliis 
can rot be conveniently done until wo have passed 
thiougii the dcsci*iption of tlie organs at the base of 
tlie brain. 



Fig. ica. 



TkAraHc imrtmn of mrA of 



Combtiwiinn nf resplrwierr 
and ktaoraollTV giiigllfc 




CHAPTER XVT. 

OF THK BRAIN. 

lirmn: ita .SrnteAuv. — /tt Motor and Stiuoiy ParUy HrmirpttnTs, and ComtJtia.-narM. — ' 
Tir .VcMforiuM. — I'ariaiiont qftlte IlemisfJtent Ui Siae and Watjht. — lottrmmMal Salvre 
nf C^rtbrtim. — 7j4« CerfMbaii: Um Strwfun lUirf F^mrtumt. — 0>-ordiwit(M mvKvhr Motions. 
— OMoecfHM mVA Amatii<e»ts». — /'Arrtofoyy. — Oandtliont of Action y lirain. 
^mmetrieal DouHmen ^Om Brmm. — /'wirtion oftitch Hal/, and of both row/otnr/y. — /intrprnd- 
cnQB and IimionStiatitM ^tatk Ihtmnfthtre.—DoiAU Thout/ht. — Ailentate Tttowjht. — .Soitf- 
matt ly* /Ve-erufeHcv. — Lou of J'rrcfpiion of Time. 

Thk cerebrum and cerebellum, being organs additional to the spinal 
cord, and developed, as has been shown in the last cimplor, ^^ 
upon i^ tlie cord being able to discharge its own functions of siruciure of 
independently of them, we shall liiid it at once tho most ' 
natural and most commodious inetliod to consider their sfructurcs as 
arising out of its structure, and tlicir functions as liaving relation to ita 
fonctions. 

A general idea of the stmctnre of the brain as an ap\»endagc to tUe 




314 



THE DRAIK. 



spinal cord may be gathered hy considering that a btforc&tion of tk 
libres takes place in the uicduUa oblongata, and upon one oi* the ^^ 
suiting bundles, tlie cms cerebri^ tUe cerebrum i^ formed, on the otber 
the cerebellum. Tiie crua cerebri is composed of three strands : an infe- 
rior, the tibres of which have come from the anterior pyramids, and m 
part from llic olivary Ixxlica. This strand ends in the corpus strialmn, 
its fibres not, however, blending abruptly with the vesicular matter, ta 
passing into it in bundles. It is cssL-ntially motor. A superior, vhkfa 
is derived from the posterior pynmuds, and tcrmiiintcs in the thalamu. 
It is eascntiaUy sensory. Between thcac, constituting the third portion- 
strand it can scarcely iritli propriety be called — is a layer of dark veJi^ 
ular material, the locus nigcr. It is to bo understood that the motor 
strands of tlic opposite sides decussate in the medulla oblongata ; tie 
sensory strands decussate in the mcsoceplialon. 

The oUicr bundle, arising in the original bifurcation, assumes the de^ 
rorroation nt igualion of cnis corebelli. On it the cerebellum is devcl- 
the wroiwUum. o|^j, j^ consists essentially of fibres from the Pcstifonn 
bodies, re-cnforccd by others which have come from the anterior pyramids 
under the name of arcitbrm tiiiros. Tlicse together make their way to 
the interior ganglion of the ecrebcUam, the corpoa dcutotum, and there 
they end. But the crus ccrebcUi contains likewiso two other gmt 
strands : an inferior, which constitutes the commissure of the two coc* 
bcllar hemispheres, and which, running round the cutiro proloogalionaof 
the spinal cord, forms the pons varolii ; a 8ui)crior. the processus car* 
belli ad tester, whicli unites the cerebellum and cerebrum. 

Of the portions of the spinal cord on whicli the cerebrum is to be de- 
veloped, those which arc sensory end in the optic thalamus, tliose which 
are motor in the corpus striatum. The thalamus and striatum of eaek 
side may be regarded as one coui|X)und ganglion, since, like tlic coli 
of the cord, they are united by a gray and a white commissuic. Oft' 
jMjrtiona on whidi the cerebellum is to be developed, the termination is 
in the central ganglion of the cerebellum, the corpus dentatum. 

At the place of bifurcation of the constituent strands of the crus cere- 
bri and cms cercbclli from each other in the medulla oblon- 
gata, there is intercalated or included a ganglion, which, with 
its apparatus, constitutes the olivary body, the fibres of which make 
their way upward between the two preceding bundles, and, having bi- 
furcated, one branch goes to the quadrigemina and the other to tlio op- 
tic thalamus, the latter constituting, as has been said, a part of the 
crus cerebri. The seat of power of tlie medolla oblongata is in this 
ganglion. 

Such being the anatomical construction of the cms cerebri, it may bo 
pliyaiologically regarded as a compound strand, tho anterior portion of 



-ttch 



J 



THE BHAiy. 



815 



I 



I 



I which U motor, the posterior sensory ; and between these a Hnrvm of the 
dark vesicular deposit, tlie locus niger, wliicli is continuoas Mrvstrandrrs 
hetween tlie vesicular matter in tlio spinal cord and that of »pei:tiTelj-. 
the thalamoa and corpus Btriatum. From the lowest extremity of the 
oord to these great ganglia there is, therefore, an unbroken vesicular 
channeL In its progress onward to the corpus striatum, the anterior 
strand yields roots of the spinal accessor}', hypoglossal, facial, abducens, 
the small root of the fiftli, the trochlearis, and the oculo-motor nen-es. 
If there were no other proof of the motor character of this strand, the 
motor proi)erty of all thc^c nerves would he sufficient to determine it. 
In like maimer, the posterior strand yields the pneumogastric, the gloaso- 
pharjTigcjd, and the sensory root of the fiftli, from the sensor)* functions 
of which its sensory character is estalilished. 

The layer of vesicular matter which is found upon the cerebral convo- 
Intions, and which is doubtless the seat of the higher intcl- R«Ution of ihe 
Icctual qualities, has tliereforo no communication with the J^^orf tile ^ul- 
vesicular matter of the spinal axis, by contact or continua- bpUewj. 
tion, but only llirongh the intervention of lihrcs which radiate upon it in 
all directions from the thalamus and striatam, or rather through some 
which radiate from the great sensory centre, the thalamus, to the periph- 
ery of the ccrcbruro, and others which converge from that periphery to 
the great motor centre, the striatum. If the diameter of these fibres be 
assumed to be ^^{^ft of on inch, there must be many millions of tlicm 
in tlic o^regate. The vcsicukr matter of the hemisphere is arranged 
on tlie supcHicies instead of centrally, on account of tho necessities of 
their structiire and condition of activity, for thereby a great surface is 
obtained, which is further increased by the artifice of convolutions, a ve- 
sicular surface which, counting in tliat of the cerebellum, has been esti- 
mated at 670 square inches, and blood can be copiously supplied and 
freely removed. 

But the thalamus and striatum are only two of a cliain of ganglia be- 
ttcath the cerebral hemispheres. Anteriorly we find the ol- caneliii at the 
factive ganglia, or bulbs of the olfactory nerves, which are VnMofiiM) 
seated upon [xxlunclcs, though their character is manifo-st from 
the gray matter they contain. Behind these are the tubercula quadri- 
gemina, to 'which the optic nerves run, and wliich are tlicrefore their gan- 
glionic centres. "What answcxa to the auditory ganglion is lodged at a 
distance back, at the fourtli ventricle, and the gustatory ganglion is in 
the medulla oblongata. These are the ganglia of special sense, and to 
be regarded as suhordhiate to the thalamus, which is their common 
register. 

All these parts are coramissured with one another, and with their fel- 
lows of the opposite half of the brain. Indeed, so likewise are all ita 



L 



TITE BRAW. 



romm[««ire« of pflfts, tlic different cerebral iobcs, the opposite hcmiBpherea, 
ib« train. adjacent and distant convolutions, the ccrDbram with tiif 

cerebellum. Hence arisen a atnicture of extreme complexity. Among 
the commiasural apparatus may be more particularly mentioned the exu- 
pus cnllosum, the ibrnLx. the anterior, the poatcriori the soft, and the N^ 
[>crior longitudinal commissures. 

For the sake of a clear conception of the structnrc of the bnin. so fax 
A»p*rtaofth« *s ia required for physiological purposes, the annexed repre- 
braJn. sentations of its superficial aspecta are given. These are a 

preparation for the diagrammatic sketches whidi follow, and which cai- 
ble us to understand the relation and dependence of tlic more prominent 
parts. It need scarcely be added that tJio uses and functions of nearif 
all the subordinate parts are at present wholly unknown. For the time 
being, they are therefore objects of interest to the anatomist rather than 
to the physiologist. 

J*'iff. 154, external lateral face of the right half of the brain : 1, mo- 
dulla oblongata ; 2, pons varolii ; 3, cerel>cllum : 4, pncumogastric lob- 
ule; 5. frontal convolutions ; G, parietal convolutions ; 7, occipiUJ ooa- 
volutions ; 8, fissure of Sylvius ; 9, 9, its two brandies. 

Fig. 154. F(ff. 1RV 



Kstcnul teUnl fltw of Itw hnln. 




Fig. l.'io, superior asj)ect of the brain : 
1, 1, anterior lobes ; 2, 2, posterior lobe.** ; 
3. 3, great median fissure ; 4, -t, fissures ^'"^" .n«i «r Uh. hr^ 

of Kolando ; 5, 5, anterior parietal convolutions ; G, G, posterior parietal 
convolutions ; 7, 7, rudimentary parietal convolutions ; 8, 8, frontal con- 
volutions ; 9, 9, occipital convolutions. 

Fig, 156, internal lateral face of the right half of the brain: 1, half 
of medulla oblongata ; 2, half of jwns varolii ; 3, half of cms cerebri ; 4, 
nrbor vita' of cerebellum ; 6, a([uediict of Sylvius ; 6, half of the valve 
of Vicussena ; 7, two of the tubercula qnadrigemina ; 8, half of the pin- 
eal gland ; 9, its inferior peduncle ; 10, its anterior pe<Iuncle ; 11, trans- 
rcrso portion of the fissure ofBidrnt; 12»8u^tiorfaceof the optic tract; 



J 



THE BRAIir. 



317 



^ ? o 



"-^ii. 



InlaiuJ latcnl tmax of th« bnln. 



fT^ i.-.r. 



13, its Internal fncc; 14, commis- 
siua mollis; 15, int'andibulutn; IG, 
portion of pituitary gland ; 17, por- 
tion of tuber cinereon.; I8,pisilbrm 
tubercle; 19, locua pcribratus; 20, 
oculo-motor nerve; 21, portion of 
optic nerve ; 22, anterior cerebral 
commissure; 23, foramen of Mon- 
roe; 24, fornix; 25, septum luci- 
duni ; 26, orpus callosuni ; 27, 
splcnium ; 28, genu ; 29, sinus of 
the corpus collosuni ; 30. gyrus 
fomicntns; 31, internal convolu- 
of the anterior lobe ; 32, deep anfractuosity; 33, convolution of pos- 
lobe ; 34, anfractuositjr. 

J*^ff. 15V, base of the brain, photo- 
graphed from a wax cast: 1, 1, autcii- 
or lobes ; 2, 2, middle lobes ; 3, 3, pos- 
terior lobes; 4, anterior portion of great 
median fissure; 5, itu posterior portion : 
6, C, fissures of Sylvius ; 7, 7, antcro- 
posterior portions of (he great iissure 
of Bichat ; 8, tuber cincreum ; 9, 9, 
corpora albicantia; 10, locus pcribratus 
medius ; 1 1 , 1 1 , crura cerebri ; 1 2, pons 
Tarolii; 13, medulla oblongata; 14, 
14, anterior pyramids; 15, 15, olivarj' 
bodies; 16, 16, restifi^nn bodies; 17, 
17, lateral lobes of the cercbcUuni ; 18, 
portion of its middle lobe; 19, 19, 
wo small antero-]>osterior convolutions of the frontal lobe, sepai-ated by 
|bo groove of the olfactory nerve; 20, oblique convolution, limiting tlic 
ure of Sylvius ; 21, convolution of tbc great cerebral fii^sure ; 22, ol- 
totry ner^■e ; 23, its bulb ; 24, 24, optic nen'cs and their chiasm ; 25, 
5, oculo-motor nerves ; 20, 26, [uithctlci ; 27, 27, great and small roots 
the trifacial; 28,28, external oculo-motorncrves; 29, 29, facial nerves ; 
►, 30, auditory; 31, 31, glosso-pharjTigcal; 32, 32, pneumogastric 
es; 33, 33, spinal accessory; 34, 34, great hypoglossal. In litis 
ring several of ttie s^-mmetrieal numbers arc not repeated, for the 
of deamcas, 
^i^. 158 is an analytical diagram of the brain in a vertical section 
m 3Iayn). It ser\"es to impress on the mind the foregoing sirm-turp of 
ictural descriptions, s, Spinal cord prcjiaring for bihirca- ^^^ ^^""- 



Vr/ ^-" 



r v; 



Duo uTUie knirt. 





tion ; r, rcRtiform bodies passing to tf, the ccrebellani ; d^ corpuB denti? 
turn of the ccrelioHum ; fl, intnrcaUtion of the olivary Ijody ; y^ columns 
continuous witli the olivary bodies and central part of the niedolU oV 
longata, and ascending to the tubercula quadrigeniina And optic tliahuni; 
p^ anterior pjiamids : r, pons varolii ; n, ft, tubercula quadrigcmina; 
g^ geniculate body of tlic optic tlialanms ; ^ processns oerebelli ad leates; 
a, anterior lobe of the brain ; q^ jwflterior Iol>e of the brain. 

Fig, 159, the motor tract (fioin SirC. Bell). A, A, Hbrea of the hcin- 
iflphcrcs converging to form the uiitcrior ]K)rtion of the cms cerebri ; K, 
the same tract when passing the cms cerebri ; C, the right pymmidal 
body, a little above the point of decussation ; D, the remaining part of 
the pons varolii, a portion having been dissected off to expose B. I, 
olfactory nerve in outline; 2, union of optic nen-ea; 8,8, motor oculi; 
4, 4, pathcticus ; 6, 5, trigeminus ; fi, (>, its muscular division ; 7, 7, its 
Mnsory root ; 8, origin of sensory root from the posterior part of the me- 
duUa oblongata ; U, abducens ocrli ; 10, auditory nerve; 11, facial nerve j 




THE MOTOR TRACT. 



I' 



/,( 



i 



,V 



^\*- 



/ 



^ 



Sid 



Th* nolor mt/L. 



12|Cdgfath pair; 13, bypojii^loss^il; 14, spinal neircs; 15, spinal acces- 
sory of right 8ido, seporatctl from par vaf^im and plo3SO-pha^^^lgeal. 

i^ig. lUO (on tbe following page), the sensory tract (irom SirC. Bell). 
A, fXHu varolii ; B, B, sensory tract separated ; C, union of posterior 
columns ; D, D, posterior roots of spinal nerves ; E, sensory roots of tlie 

» fifth pair. 
Tlie ganglia at tlie l>aso of (he brain are regarded by Dr. Carpenter as 
constituting tho true sensoriuni, a doctrine which he has cs- ^^ 
tftbliftfacd by many wciglity arguments, and which is doubt- 
less one of the most important thvis far introduced by any physiologist. 

Tbe idea licrc intended to l)e conveyed is, that the thalaini, striata, 
BCtaorj ganglia, and ncr\'ous arrangements below, constitute on isolated 
apparatus; distinct from which, and superadded, are the cerebral hem- 
ispheres. 

From observations on the animal scries, the conclusion seems to bcun- 



820 




TtM Monrj ttMt 



avotilnlilc that tlic chain of ganglia now under consideration must cca* 
,f;titutu n Kcn»oriuin, the centri^wtal fihrea com nrnni eating their impression 
rjid motion ensuing, the impressions being attended witli consciousneaa. 
This view is tnorcovcr substantiated by observations made after exciaicm 
of the cerebrum, a certain degree of consciousness remaining, not unlikf 
that exhibited hy a man who is half asleep. This condition of things 'a 
natiu'all}' presented in tltc amphioxus. 

J$at after the cci'ehral licniis]>hcrca arc added, an impression received 
EflMofibeid- '^P^" *^° thalamus, whether it has come in through the so*- 
dlttononhe sory ganglia, or any other sensory part of the cranio-spinal 
**'* "'■ axis, is transmitted to the ccmvolutiona along the radiating 

fibres. From the convolutions, the influence whicli is to prodaoo n»- 
tion descends along the converging fibres to tlio striatum, thonoe along 
tlio Ulterior layers of the crue, through tlie meHOcephalon to tlio anterior 
lyramids. and by their decussation to the opposite side of the cord. 

Sueii is the view which Hr. Carpenter prescjits of tlie functions of tlie 
sensory ganghu and spinal axis ; or, employing the terms no have pre- 
viously dolined, the cord alone is a lon^tudinal scries of Mitoraatic arcs; 
on the addition of the tlialanius and striatum, it becomes a compound 
registering arc, the cerebral hemispheres finally annexed to it constitut- 
ing an inBucntial arc 

In a simple arc, an impression is at once converted into motion, and 
leaves l)chind it no traces ; its expenditure is instantaneous and complete. 
In a registering arc, a part of the impression ia stored up or remaiiu — 



THE CEREBROI. 



321 



I 



nay, ©vcn (lie wliole of it may be so received and retained. It la not to 
te overlooked that, as soon as this effect occurs, the evidences of sensation 
arise; and, since sensation necessarily implies the existence of ideas, 
ideas tliemselves arc doubtless dependent on this partial retention or peg- 
istjy of impressions. We may therefore adopt the doctiine of Dr. Car- 
penter, as regards the sensorial fiinctions of the cranio-splnal apparatus, 
tool only from the arguments he has presented, but also from otlier con- 
siderations. 

There can be no doubt tliat the cerebral hemisplieres constitute the in- 
strument through wliich the mind exerts its influences on the General resalt 
liodv. An3- injur}' of sufficient severity inflicted upon them "f v.-iriaii«ii 

- * 1 I • 1 11 /••It 1 in th« size and 

Is at once attcnaou witii a totju loss ot mtcUectual power; wtiRiiiofiha 
any malformation or lesion by disease is attended liy a dctc- ''*-'>»"'p'>p»«' 
Tioration liclow the customary mental standanl; any unusual develop- 
ment with correspondingly Increased powers of intellection ; and this not 
only as regards animals of difterent tribes, or individuals at special peri- 
ods of their lives, but also of different men when compared witli one an- 
other. The general impression is founded in fact tliat those who have 
distinguished themselves fur mental attainments or intellectual power 
have been marked by the unusual development of their cerebral hemi- 
spheres. 

It is to be understood that, in tlms asserting a correspondence between 
the development of tlie cerebrum and intcllectn.al capability, . . 

we are not to overlook the instrumental nature of that organ, nature ofccK- 
Though imperfections in it may produce a manifest inferior- '""°' 
ity, that inferiority is by no means to be referred to the intellectual prin- 
ciple itself. The mode of action being by an instrument, if that instru- 
ment becomes imperfect the action Iwicomes imp<^rlcct too. Under such 
circumstances, in any human contrivance, we should never (hink of im- 
puting inferiority to the prime mover. 

From tliis point of view we may tlicrefore consider the intellectual prin- 
ciple aa possessing powers, propci'tied, and faculties of its own ; as being 
actc<i on by impressious existing in the thalamus, and delivered througb 
the intervening tibroua structures to the vesicular material of the convolu- 
tions of the cerebral hemispheres. In this region they act upon the in- 
tellectual principle and arc acted upon by it, the returning influence, if 
any, coming down through the converging tubular structures to tlie cor- 
pus striatum, aud by its commissural connections sent otT to particular 
ganglia, passing along the inferior strand of the cnis tlirough the mcso- 
cephalon to the anterior pyramids, and by their decussation to the oppo- 
site side of the cord. 

Having thus spoken of the sensoty ganglia and the cerebral hemi- 
spheres} it remains to add some remarks respecting the cerebellum. It 

X 



322 



STRUCTURE OP THE CEREBIIIXUM. 



n» oenbel- arises, as has been stated, from the triple Htrand of tlic cnia 
Iwn- cerebcUi, of wliich one layer of tibres is connected with tl« 

corpora quadrigcmina, and throngb tltom with the optic thalami ; a sec- 
ond with the rcstiform bodies ; and tlic third ia commissural, and paaan 
tbrwanl as the pons varolii. 

Like the cerebrum, this organ is vesicular on its surface^ which pre- 
sents a number of parallel lines, which ore fissures descending to the in- 
terior. Their object is apparently the same as tliat of the convolattODB 
of the brain, tlio augmentation of surface. Of these fissures, th« deep 
are termed the primary : lliey divide the organ into lobes. Those whidi 
descend to a less depth arc termed secondary : tlie dirisions lliey gitt 
rise lo are lobules. The gray vesicular material does not, however, de- 
scend to the bottom of tho primary fissures, and in this respect they dif- 
fer from the cerebral convolutions. Moreovcrt from this circumstanccv 
that material is not continuous all over tho cerebellum, but is in divided 
portions. 

Such arc the appearances presented on an exterior exatninatiou of 
Stnieiuraof ^ho ccrebclluiii. Viewed as a development upon the crun 
ihecewUUttm. ceiebelli, it may be described as consisting of a median loU 
and two Iicmiaphcrcfl ; the former is, however, found existing alone in lialh 
cs and roptilod, the latter being subsequently added in the liiglier trilxfl. 
From the central column of each hemisphere white fibrous planes are 
given off, and from these, again, secondary, and again, tertiary planei 
proceed. The planes are covered with vesicular matter, and tlius grre 
rise to the appearance spoken of in the preceding paragrapli, in the exte- 
rior examination of tlic cerebellum, as primary and secondary fismiTffc 
They are lined with pia mater. The median lobe is formed on the mM 
plan. Its fibrous stem comes from the processus ccrobclli ad testes, or, 
more properly, from the optic thalamus. The weight of the ccrebcllam, 
compared with that of tlie ccrehmm, is usually stated as being about 1 to8. 

Much diversity of opinion prevails respecting tlie true function of the 
ccrelx;llum, some supposing that it is the centre of common sensation, 
others tJiat it is for the purix)se of co-ordinating muscular niorem^t, 
and others that it is tho scat of sexual instinct. 

That the cercl)cllum is one of the sensory ganglia may be inferred from 
FaBctbmorUM ^^^^ history of its development and its anatomical connec- 
cerebeUuro. tions. Its median lobe is the first to appear, as in fislies, 
and the hemispheres arise subsequently as appendages thereto, as in 
tnrds. The size which these eventually attain g^ves tliem a deceptive 
prominence, and hides their sulwrdinate character. Kcgardiug the lobe, 
therefore, as the essential and fundamental portion of tho structure, the 
signiticancc of its cerebral connection with the thalamus through the pro- 
cessus ad testes is too obvious to be overlooked. As by tliis its , 



aen^^ 



PLTfCTIONS OF TirE CEREBELLUM. 



323 



\ 



I 



\ 



ry dmrnctcr is displayed, bo the same holds good for the Jiemiaphenea, 
tbetr relations with the spinal cord through the rcstiforin bodies being 
■Ibo of » sensory nature. It seems probable that the superficial vesicu- 
lar material is in anatomical connection with the tlialamus, and the cor^ 
pus dentatuDi or inner ganglia with the posterior or sensoiy colomns of 
ihe cord- 

Thc arguments which have been brought forward by those who sup- 
poee the cerebellum to have for its office tlio co-ordination of Tho aoctrin» 
general mnscolar movement, may be briefly quoted as fol- [^^'iJ^^l^uI 
Iowa : There appears to be a general correspondence between mocioii. 
its size and the degree of energy and complication of the motor powers 
ia various animals. Thus, in tisties, and likewise in birds, those tribes 
which excel in their powers of motion, or arc distinguished by the com- 
plication of their movement?, are chametcriKed by the manner in which 
thia organ is dcvclojKyl ; and the same may |je wii«l even of the mamma- 
lia, quadrupeds whose locomotive mechanism is simple posscssuig it in 
a lower state of development tlian those which either temporarily or 
constantly move on the posterior extremities. Among apes, those which 
more frequently assume the erect posture, which is normal to man, have 
their ccrelWhim of a size more closely approaching to his. 

On examining such facts, it appears tl»at it is not so much muscular 
as tho quality of co-ordinating and governing minute muscular 
tDotions. To maintain the standing position motionless, there are, in re- 
ality, a great many muscular movements required, which serve to antag- 
onize all the little incidents producing a tendency to tall ; and if this be 
00 in standing, how much more difficult must such antagonizing and 
compoHsating actions l)ecomc in walking, running, and snch movements. 
Theoictically, it might be cxiwctcd that some sjwcial organ is necessary 
to combine such various actions, and that organ seems to be the cere- 
bcllnm. 

In contirraation of this are the experimental results which have l>ccn 
obtained. The cerebellum, on irritation, gives rise to no Rwulu of ex- 
convnisive mr)tinns. nor to sensations. If removed by de- ih« "^ii!i. 
grecs in snccrssivc slices, the motions of tin* animal beirome turn. 
irrrgubir, and, finnlly, it loses all power of walking or of maintaining its 
iHjuilibriuni. Though the powers of the animal in bringing its muscles 
into contraction sccni not to Iiave suflcreil, it can not co-ordinate or com- 
bine the necessary muscular exertions, and, as is graphically stated, stag- 
gera and falls over lik(! a drunken man, still making efforts to maintain 
ifa balance. Such exix^riments have Ix^n rcpcate<lly made in the case of 
diSoicnt animals, and with the same results. 

Connected with these results of experimental lesions of the cerebellum 
are the rotations, as they are tcnned, which occur, for ex&m^\c,^\wsv «ftft 



VOCTIUXE OP PHREXOLOGT. 



BotairmoiJoM of the cTUTa corcLclli is cut, the animal rolling upon itsW 
efaniiult. gittidinal axis for a long time and with great raptilitr. 
From such facts, it has therefore l)een concluded that the function of iLe 
cerobcUum is neither for sensation nor intellection, nor is it the source of 
voluntary movements, but that it is for tlio government or contrvl of 
combined muscnlar action. This is the view of il. Klourciis. 

II. Foville supposes that tlic cerebellum is fur tlie perception of ihc 
Doctrine that scnsations derived from the rausclea, and enabling the nuul 
inreiteiiimi if \q excrt tt guiding action. The facts whicli support the pR- 
Uon of mnwa. ccding vicw suppoft tlils aUo, there being, moreover, in tliic 
lar •euBiUoiu. cjitjc^ an additional argument derived from the comiection 
which the cerebellum has Ix^n shown to maintain with the scnson' col- 
nmns of the cord, and the pain experienced on irritating the restifbtui 
columns. It Iiaa likc^viso been pointed out that this hypothesis iilna- 
tratcs the connection between the cerebellum and the optic ganglia, as if 
it were for the puqiose of bringing the oigans of sight to the aid of tiiis 
co-ordination of muscular motion. 

A third hypotlicsis, to which allusion has been made, ia, that the cere- 
^ ^ ^ bellum is the oigan of sexual iustijict, or of amativetiess, as 
It U Um orftan it is texmed by phrenologists. Tlic evidence of this^ wlua 
orsMUTKMiM. fjjjyjy. examined, i.% however, vay far from afibrdtng a fiill 
proof; indeed, in many instances the facts arc in direct opposition to 
the doctrine. In castrated animals the cerebellum uudcrgoes no dimi- 
nution. Tliere ia no coincidence between the intensity of that instinct 
in the diifercnt animal tribes and the degree of development of this or- 
gan ; and where it has been in a diseased condition, there lias not been a 
necessary corTCS]iondence between the lesion and the loss of the instinct 

This view of the ftmction of the eercbcllum is connected with tlie doc- 
trine of special localization, or phrenology, which may therefore be here 
briefly considered ; the general expression of iliis doctrine being that pir- 
ticuliu regions of the brain arc devoted to special fnnrtioms 
and that by an ina[>cction of tbo exterior of the cranium men- 
tal peculiarities may be detected. Drs. Gall and Spurxheim considea^J 
thnt this >-icw is supported by the fact that the specialization of functij|^| 
in the brain is agreeable to the general mechanism of the system, in 
whicli particular organs are charged with particular duties ; that, in any 
individual, the mental powers are not equally or jiroportionally developed, 
but some at one and some at another period of life, and so likewise of theii 
decline, some remaining at their original strength, while others may have 
Artfumcnu in bocome scriously impaired. It docs not appear liow each 
Curlti^'^rf '^^^^ ^^*" ^ cxplmncd upon the h^-pothesis that tlic whole 
functioiu. brain acts as a imit. Thoy may be readily Qndcrst^x>d if it 
he supposed to act by parts which are developed in sncoeesi^o. Tlie 



rbttDoioK^-. 



■VnnGHT OP THE BRAI?;. 



S23 



fsBnic condusion is arrived at from well-known facta connected with in- 
lity, in which it \QTy frequently happens that some of the faculties 

lalotie are deranged, wliLle the others retain their power, and some raay 
tven become more {x^rfcct than before ; so. likewise, in drcamiitg, some 
of the faculties retain tlii-ir activity, while otherH have become torpid; 
and fio, likewise, when diflereiit individuals are compared, some exhibit a 
superiority in one, and Bome in another mental particuhtr ; and it is as- 
serted that where the Bame peculiarity has predominated in different in- 
divitluaU, it ha3 always been attended by an unusual development of a 
special locality of the brain. Nor is there, in these views, any thing that 
flitandd in contradiction to the general plan upon which the nervoua sys- 
tem itself is constituted, as is manifested by the different sensor}' gan- 
glia for vision, hearing, or smell, or the arrangement for motion or sensa- 
tion presented by the spinal cord ; and, moreover, they arc supi>ortcd by 
the com|Kirative anatomy of tliis system ; for, whatever grade of animal 
Kfe "WO mav consider, the appearance of a new function or of a new in- 
stinct 13 certain to ho connected with a new and contemporaneous devel- 
opment of some part of the nervous system. 

The facta which have been obser\'ed in cases where one ccrchral hem- 
tsphcTTS Ims cither suffered lesions or lost its functions, do not present 
■ay contradiction to the preceding doctrines ; for, though the remaining 
hemisphere may seem to act eqnally well alone, as did both together, we 
are very apt to deceive ourselves as rcgiu-ds the actual facts, a statement 
which may be illustrated by recollecting how easily we persuade our- 
selvea tliat we sec witli one eye as well as with two. No doubt, in many 
of the ordinary cases, one iicmisphcrc of the brain may, like one eye, seem 
to act well enough, but a more critical examination proves that in otlicr 
casea this is tar from being true. That the two hemispheres act sever- 
ally and separately is clear irom what sometimes ensues in diseased con- 
ditions of ono of them, or when, perhaps, there is a want of symmetry 
liptween them, those remarkable forms of mental derangement, some- 
times known under the designation of double life or duality of mind, 
thrn ensuing. 

In man, the weight of the brain averages alxiut fifty ounces; in fe- 
males, about forty-tive; the maximum being about sixty-four, Weiphtofihe 
and the minimum about twenty ; in the case of idiots, the '^*^- 
mean specific gravity of the gray matter is stated by Dr. Sankcy to be, 
in Iwth sexes, 1.034, but somewhat less early and late in life. The 
Fpecific gravnty of the white is 1.041, and this varies less vnth sex and 
time of lite than the former. 

The functional activity of the brain depends on the copious supply of 
blood. It is computed that one fifth of the whole qnaniity in 
"3fCuIation is sent to this organ. It is delivered through ihc two 



326 



rit£SSURE ON THE BKAIN. 



Pu iv ot J"tc""^l carotid and two verteliral arteries. The impetai d 
iiltHMi'to ibo tUo carrcnt U checked by ttio Rinuoas eonrse these Toaeh 
^"^* take, or by their breaking promptly into capillary branches 

A freedom of auastouioeis among them» as is well displayed in tlie circle 
of Willis, ail'ords abundant provision for accidental stoppages or re- 
fitrainis. 

Although the brain is inclosed in an unyielding ctt\*ity, it U sn* ' 
j^^^j^ . the prcsatiro of the air, a fact which, though it has b- 
pnwaraovtlM uied by some physiologists, follows li?om ordinary physiol 

°* principles. And since the quantity of blood present at any 

moment in the organ varies with the contemporaneous functional activ- 
ity, being greater 03 that activity is greater, the ecrebro-spinal tluid also 
varies in amount. Through this iluid an equality of prcssnre is tben:- 
fore insured^ no matter what may bo tlio quantity of blood in the brain. 

The ccrebro-Bpinol fluid, the quantity of which has bt^n eatiroateil at 
c«r«tiT&4p)Ml two ounces, is readily absorbed and as readily reproduced, 
fluid. rpj^ ^^^ ^^* ^justmcnt between it and the blood roquiriag & 

certain period for its completion, tho brain can not instantaneously he 
bronght to its maxinium action. Thus, as all jjcrsons observe, when we 
undertake any unusual intellectual duty, tlierc is a certain prepanitoiy 
period to be passed tlurougli, as the common expressinn is, '^^for coiupOi- 
ing the thoughts.'* 

Pressure upon the brain, either applied moclianically or tlirough occi- 
r.ffect of mc- dental effusions, produces at once functional ijiactiviiy, prob- 
ciianimi pre*, ably by intorfcrenco with tho due circulation of the blood; 
chongva in tha and, in like manner, any marked change in. the chemical le- 
i>loo«L lations of that fluid exerts on the brain a corresponding ef- 

fect. Tims, when oxygen gas is breathed, or, still better, protoxide of 
nitrc^n, which is more soluble in the blood, the processes of intellection 
go on in an exaggi^rated way, and ideas in rapid succession, and iu unu- 
sual forms of combination, flit tlu-ough the mind ; but, as the consequenee 
of this, since the lungs can not remove with the necessary promptness 
the carbonic acid which is arising, the narcotic effects of that body w 
soon experienced ; and this is also the case in alcoholic inlosuoation, in 
the advanced stages of which the accumulation of carbonic acid in the 
blooil gives rise to the simic result. 

That different regions of the brain have independent though matnallj 
nn^ctoftUs commissured faculties, is fully established by the phenomena 
SoulAh*™' *** '''*^ ner^'cs of sense, nor can there be any doubt that these 
iir*iii. diflcrcnccs of physiological function arc directly dependent on 

differences of anatomical structure. It is, indeed, to structural differences 
that we should impnte tlie greater or less ethniency of llie whole organ, 
as much as to differences of its weight Because of a higher claboralio 



to — ' I 

laboration, 



D0UDLEXE3S OP THE NEBVOCS 8TSTEW. 



the brain of one person may Lc more energetic than tliat of another, even 
.ugh its weight may be less. It is not to be denied, however, that there 
i connection between mental power and the quantity of cerebral matter, 
when individuals of the same kind arc compared, or that in the animal 
scries the psychical powers decline as the cerebrum diminishes in alze. 

few topics are more worthy of the attention of the physiologist than 
tli&t of the variable psychical power» of man, and yet few liave .^^ j^. . 
been more overlooked. By variable psychical poivera I mean psychiaJ 
those periodicities of increase and diminution in our intellect- P^'**"- 
xul efficiency, whicli may be noticed not only in diseased, but aUo in 
beaithy states. On the principles wc have presented, these find their 
explanation in the temporary physical states of the organ, such as its 
condition of repair, its existing facility for oxidation, and the constitution 
of the blood as respects a proper artcrializntion- 

The most striking structural characteristic of the nervous system is its 
symmetrical doubleness, the cranial and spinal nerves com- SjrametricAt 
ing forth by pairs to their distribution on the right and left 'll^^lZ'^.^' 
sides of the body. The manner of development from tbe i«p>. 
spinal axis laterally impUes such a construction, and, indeed, gives ori- 
gin to two halves so equal and alike that it has ot^n been said eadt 
person consists of two separate individuals. Examining those organs 
which, by reason of the elaborateness of their mechanism and principles 
of action, enable us to determmc with satisfactory precision p,jn^j[on ^r 
the function discharged by each one of the members of the ucb lateni 
pair, as in tlie case of tlie eye or the ear, we may come to tlie '"^*"- 
following conclusions : Each is a distinct organ in itself, capable of its 
meeting the requirements of tlie economy in a sufficiently satisfactory 
manner, and therefore forms a distinct whole; but the pair can likewise 
act simultaneously, re-enforcing, to a certain degree, each oth- ,. . . , 
er*fl power, though in this double action there by no means iiuabio otsaim 
arises a double intensity of cifect. The closure of one car ^^^ J^iJj! 
to a sound does not diminish the loudness by one haJt^ nor cnyuoUieir 
docs the shutting of one eye reduce to one half the bright- P"*^*"*- 
ness of a light ; but, though there is not such a doubhng of cffeet when 
both eyes or both ears arc employed, there is a degree of precision in the 
resulting indication which is not to be gained by the use of one of ihcso 
o^ans alone. In such a double organ, then, the result is not so much 
a heightening of the final impression as the giving to it of a greater de- 
gree of precision. 

Uorcover, each organ seems to exext a compensating influence over its 
fellow in any deficiencies or imperfections it may p^ssefS. Comt^-n^aUoa 
Thus it is rare that both eyes are of an equal optical g.cd- *''"''"f*^*^ 
I, as most individoals will find on making a personal examination; 



E 



328 INDEPENDENT ACTION OP EACH HEanSPHEHE. 

but in vision with both eyes the faults of the more imperfect one aw 
merged in the indications of tlic better, and tlie same might be remark- 
ed of the ear; from which it would appear llmt this doablcness of or- 
gans is rather for tlio purpose of introducing a principle of compcnaation 
tiian one of conspiring action, the object intended to be gained being a 
jufltnejs of perception rather than an increase of effect. 

These observations apply to double organs in their normal states, or, 
EOkctoricm- if not their normal, their Iiabitual ones; but if to tJie erev 
iiorftn- diuurh. f^^ example, a temporary disturbance is given, as by prea^ 
g»n. ure which renders its optical axis oblique, the fdlow OKpo 

being permitted to rt'tnin its usual position, double sight is the rosah, 
It is true that, in the habitual divergence of strabismus. 8uch is not the 
cifcct, one of the images disappearing, or perhaps the mind, acconmK>dAt* 
ing itself to the luibitual condition, combines the two into one. ThesB 
circumstances indicate that each member of a double organ can. uodor 
conditions of difiturbaucc, exercise an independent and even opposing ac- 
tion to its fellow. 

It has by some been supposed that the mind pays attention to tlie im- 
Thelotlicstionji prcssioDs of only one of the pair of organs at a time ; thvs, 
^Mi^RmUt") *^'"* ^^ ^^^ ^^^^ imagei) furnished by only one eye, though ire 
Bi ft time. can with very great quickness direct attention to thow fur- 

nis)ic<l by the other, and therefore, deceived by the rapidity v»itli which 
tliia altcnmtion of attcnlion can be accomplished, our belief in the syn- 
chronous use of both organs is an error, if two differently colored ob- 
jects, sueli as differently tinted wafers, be so placed as to l)c fteparately 
and yet simultaneously viewed by both eyes, the mind vainly attempts 
to combine the two images together. Wc do not see the resulting form 
of a green tint, but wc see, according as our attention is gii'cn to the 
right or left, a blue or a yellow, if these have been the colors of the wa- 
fers, and these colors can quickly mei^ into one another, like dissolving 
Illtuirative vicws. There is a simple experiment which serves to support 
«xp«rlmcui. tiiia view, and which any one may readily make. If the open 
liand be placed along the nose, so as to divide the right eye from the left, 
and wo look upon the snrfaee of a uniformly-ill uminaled sheet of paper 
covered with writing, it will be found tliat we can only read with one 
eye at a time, but that the mind can with groat rapidity determine which 
eye it will use. In tliis little experiment, we have, moreover, the means 
of estimating the relative sensitiveness of the two eyes, andother of their 
optical peculiarities ; thus it will be commonly remarked that, though the 
pajwr be, as we have said, uniformly illuminated, that part of it which is 
regarded by one eye is brighfer than that seen by the otlier, this being 
duo to a difference in their sensibility. It will also frequently occur 
that the two portions of the poge will present different shades of tint, 



^ 



DOUBLE TRAIKS OP THOUGHT. 



329 



1 ore, petlmps, Iwing a faint greenish gray* vriiile tlic other ia of a yd- 
hitc, the proper color given to it by the candle or kmp by wliicb 
iia &COU. 

9 In this feature of double construction the brain itself participates, pro- 
■bttng a ri;^ht and left lialf approaching one another in form, ivitliout 
toing absolutely identical. Much, therefore, of what has been said rc- 
pecting the mutual relations of the right and left eye, and the riglit and 
pft car, niu«t apply to tlic right and left hemispheres of the brain; and 
f-is under this point of view that I>r. Wigan has regarded it in j^^^^ . 
. work on the Duality of the Mind. Nor can there be any Bciionofvacb 
ibt that each hemisphere is a distinct organ, having the "^^ ^ "*' 
?cr of carrying on its functions independently of its fellow; that, though 
can tlius act separately, both can act simultaneously ; and, jadg- 
; from the cases that have just been presented, it would seem that we 
ijUBtiticd in inferring that the common action of the two hemispheres 
1^ not for the purpose of a heightening of effect, but ordy for greater pre- 
pion, and that in the same manner as it is a rare tiling to find two eyes 
k two ears of equal goodnesfi, so aUo it is unusual to have two Iiemi- 
bherea which arc precisely alike. The defects of the one may i„i„iK.r.iini- 
i compensated by the superiorities of the other, and thus Ti^jn or ooa 
[incan result be attained; and as one eye or one car can, """^i"* 
llder the proj>er cireumstanccs, overpower its fellow, so likewise can one 
usphcre of the brain, except in certain cases, which Iiave been some- 
at imaginatively described as insubordination of one of the hemi- 
hcrea, when insanity is the result, the healthy half being unable to 
Btrol the diseased one ; and for this reason, wo often obacne of the 
! that they have synclironously, or, at all events, in a very rapid al- 
fttion, two distinct trains of tliought, and, consequently, Doublfiirainof 
ro distinct utterances, each of which may, so to speak, be »'»""«'"• 
fectly continuous and even sane by itself, but tlic incongniities that 
; from the mingling of the two betray the condition of such persons. 
k ihii! cnsc doubleness of action ia seen in its most exaggerated aspect, 
nt in a less degree, it maj' lie remarked, in the thinking operations of 
boBC whose minds arc perfectly sound. Thus there is no student but 
Bt have observed, when busily engaged in reading, tliat his mind will 
nder off to otlior things, though he may mechanically cast his eyes 
page after page; and the same may occur in listening to a lecture 
sermon. But, tliough the insane man may indulge in two synchro- 
^>U8 trains of thought, he never indulges in three, for the simple reason 
^t lie has not three hemispheres to do it with, tlie same remark apply- 
}fg to the sane man in the accidental wanderings of hia thoughts. 
The overcoming of this insubordination of one of the hemispheres may, 
a very considerable degree, be accomplished by cd\xea.uciw, q^ -^ViasS^ 




Eflfcct of edu- one of the chief results ia that it cxcrcisps us in the habit of 
"^"'- thinking of one thing at a time, of thinking therefore wiUi* 

out confusion, and of arriving at conclusions with precision and decisua. 
And tlicsc considerations should aUo, in Dr.\Vigan's Wew, he our cluef 
guido in the cure of insanity, doing all in our power to invigorate the tc- 
tion of the healthy hemisphere, and enable it to subdue tiie inanbordiiia- 
tion of the diseased one. If both hcniisphcrcs are diseased, the case is 
almo!;t hopeless. 

Of the independent and yet complete action of cadi of the cerebral hem- 
Pfrffct «cU isplieiea wo have abundant and interesting proof. 31eiital 
gf a sin^e Operations can be earned on in a profoundly diseased state of 
httmbphtf*. Qjjg ^£ these organs, as multitudes of well-authenticated cases 
attest — ^nay, even when the lesion has gone so far as to amount to *h 
absolute and entire disorganization of one of tlie hemispheres. Simitir 
evidence is also fumitthcd hy those interesting cases in which, by accidcali 
03 by gunshot wound, destruction of one side has occoired. 

Even in a state of health we have numerous examples of this inde- 
iRiennixM »c- P^"*^^"* action of cacli hemisphere. Wliile engaged in ordi- 
don or the two nary pur^uita which imply a continued mental occupation, 
emisp cre». ^^ ^^^ occasionally troubled with suggestions of a different 
kind. A strain of music, or even a few notes, may !« jierpctnally ob- 
truding, and such an occurrence we could scarcely explain save upon tlie 
principle of the 8ei>arato action of tlieso organs, the one interfering witii 
the other. That precision whicli wo Iiavo remarked as artsing^ from the 
conjoint use of two eyes and two ears ia doubtless also attained whoe 
the two hennsplioTes are acting in unison. AVo can, moreover, ^tduntftr 
rily permit one to rest while tlie other continues its duty, as we can vol- 
untarily make use of one eye, disregarding tlxe indications of the other; 
but where it is necessary to execute a critical comparison or arrive at an 
accurate judgment of things, both hemispheres are brought into action, 
^^^ as are both eyes when wc intently consider an object. 
^^B Among other phenomena, Dr. Wigan calls attention to the operation 

^^" Cftsite- of castle-building, as it is designated, as illustrating the volunta- 

■ biiUdiiig. j.y nianner in which we permit one hemisphere to act, presenting 

■ fanciful dclusiona; the other, as it were, watcliing with satisfaction the 

■ operation, and in this respect lending itself to it. Not that for a moment 
I wc suppose there is any truth in the ideas suggested, and in thia the 

■ pltcnomcnon difiers essentially from tliat of dreaming, in which it never 
I occurs to us that the scenes and actions are unsul>stantinl, 

I distill moro strikingly do those singular cases, which horn time to tine 

I Double or tl- P^"*^®*^"** thcmsclvca to tho physician, of double or altenute 

H (crnaiocDD- consciousncss, illustrate this isolated function of tho hemi- 

I ecwuitKiM. g^jjgfea^ In gQine gf ihftse, which have heen carefully ob- 



lyob- 



SENTniENT OF PRE-EXISTENCE. 



881 



aenrod anJ authentically recordodi each of theee portions of the brain has 
continued its action for a period of days, or even weeks, and then, rclapft- 
ing into a quiescent state, lias been succeeded by tJie otlier, thus present- 
ing in Eome degree an analogy of wliat is obscrred in ordinary cases of 
insanity* so far as the reciprocatiiig action of the two oi^ns is concerned, 
bat difi*ering in the period uf durution of their function ; and thus, if one 
of them should have undergone deterioration, or have satFercd lesion, so 
that it has been reduced to what might be termed sn infantile state, the 
impressionB formerly stored up in it having been for the most part lost, 
or tJiere being an incapacity in it to make use of tbcui, the patient will 
alternately exhibit what has been aptly termed child life and mature life. 
For a few days, or jwrhapa weeks, lie will conduct himself in the ordi- 
nary manner of an adult, reading, reasoning, and actuig, and then, for a 
similar period, will pass into a condition in which he docs not even know 
hid letters, and reasons and acts like a child. These phcnomrna of at- 
lemato and double intellection are intcreating in the highe-st degree, and 
aeem to be explicable on no other principle than that which this author 
snggests. 

But I do not think that the explanation which he oUcrs of the scnti- 
tnent of prcH^xistcnce is correct. By this term i.^ under- Sfndmrnt of 
stood that strange impression, which all persons have occa- it'xa^i"''*- 
Bionally obBcr\-cd in the cxiursc of their lives, that some incident or scene 
at the moment occurring to them, it m.iy bo of quite a trivial nature, 
has been witncs^d by them once before, and is in an instant recognized. 
Thougli this opinion that we have seen a present incident once before 
aomctimcs occurs in coses where the circumstances are of profound in- 
terest to us, tlie experience of most persons assures us that it is more fre- 
quently in trivial events. Dr. Wigan's view is, that it arises from the 
almost contemporaneous action of the two hemispheres, and that, under 
the circumstances, we have a confusion of memory, and are led to be- 
lieve that there has been an interval of indefinite duration, when, in 
point of fact, it was iu\ impression in each hemisphere closely coincident 
in point of tlmt*. Tills explanation turns on the assumption that this 
sentiment of pre-existcncc occurs hut once. He denies tliat we ever 
snppoee that we have seen the thing twice before. Hat I believe that 
the experience of many individuals assures them that this is not the case, 
and that they are under a fum persuasion that they have witnessed the 
■Mne incidents more than once before, nay, perhaps even many times. 
The instance which this autlior furnishes as occurring to himself, in 
whicli, on tlie occasion of attending the funeral of an exalted personage, 
and at the time of the coffin being deposited in the vault, with the strik- 
ing •solemnities of the occasion there rushed upon his mind the idea that 
he had been present at this same scene once before, a tlvlu^ nn\v\c\x \{%s^ 



LOSS OF PERCEPnOX OF TIME, 



of conrsc, nn imposslbilitr, is very instructive. But the difficulty in tbe 
way of his hypothesis lies in the fact that it offers us no exphuutlioDof 
those cases in which we are perfectly persuaded that we have witnessed 
tlie thing more thim once bclbrc, though it may answer in the particaUi 
1m* of I tniB histance hero cited. Perhaps wo may appropriately recall ik 
perc«t)tioR of wcll-known fact offered to ua in dreaming, and to which at- 
tention hereafter will be more particularly directed, that tben 
ore circumstances under which our mental oiKsrations are carried fonrtil 
with tlic most maneloujt speed. Thus a sudden sound, which awakes 
na, or even a flash of lightning, which is over in a moment, may be i&- 
corporated or expanded into a long dream, diversified with a varicms 
multitude of incidents, all appearing to follow one another in an appro- 
priate order, and occupying, aa wo judge, quite a long time, yet all nefr 
cssnrily arising in an instantaneous manner, for we awake at the moment 
of the disturbance. Of the same kind is that remarkable deception, 
wliich is authentically related by those who have recovered from deali 
by drowning, that in the last moment of their agony all the varuxu 
events of their past life, even those of a trivial kind, have como mshiiij 
before them with miraculous clearness. I^Iental oiicrations, therefoRj 
both as regards old recollections and new suggestions, may take efiect 
with wonderful rapidity, and if the sentiment of pre-cxisteiice is to be 
explained on the principle of the double action of the brain, it must lik^ 
wiao bo dependent upon the fact here presented. 



THE CnAVUt 3n5R\'ES. 



I 
I 



I 

\ 



P 



CILVPTER XVn. 

OF Tire CRANIAL SERVES AXD THE GREAT SYJIPATHETIC. 

EmtrntTiition of (he Crattial Xerves. — The TTnrd Pair, or Ocitio-molor. — TKc Fourth Pair, or Pa- 
tiutid.— The Pi/tk J\rir,or Trigtmini,— The Sixth Pmr.or Abdnemta.—IlluxtfatloHM t^ tks 
TKini^ FoartA^ Fi/Ot, tmd SUtA Pain.— The Seventh Pair, or FadaL—Uhtlration ^ the 
Fitaat — The NlnAPair,or Ohuo-pharf/nyeal — lUiutraiicn of the Ghuto-pharyn^eaL — TV 
TVjiM Pair, or Pnmmorfitstric.. — lUtutrafion of the. Pnmmogoftrie. — lUtuUrulion of Oif. Aoryo- 
yoaUt. — The Elevenlk Pair, or Sptnai Aocesaory. — The Ticeiflh Pair, or JI^pogioM$al. — /t 
btMtratiou of the UgpogtoataL 

The. f^rrnir .Vcn-e. 

Qf^ the itrtat Syvpalhelie Synlem. — P»ntion, Structure, oarf Origin of the Spofiat^tir^ — Itn R^ 
Lttkm teitk the pBemnoytutric. — Its Omnectiou itilA the Sjrinal System. — Ju Pitxiiete. — Jt» 
(J*rrtgHa. — They are Rseerroir* ^' Fora. — Smntitary of the Fmctioae of the Sympathetic — 
JUuMXrtitian o/ the Sympathetic.--' The Abfjomiaal Plexiues. — T7te Sohr PtexuM. — TV J/uen- 
teric PkTMsea: 

Tu£RE are twelve pairs of cranial nerves : 1st, The olfactory; 2d. The 
optic; 3tL The oculo-inotor ; 4tli. The pathetic; 5th. The tri- The cranial 
facial; 6th. Tlic abducent ; 7 ih. The facial; 8th. The audito- >»^""- 
ry; Uth. The glosso-pharyngeal ; lOlh. The pneumogastric; lltli. The 
spinal acccsaoiy ; 12th. The hypoglossal. 

Of these, the first, the second, and the eighth, being nerves of special 
sensation, may be more convenienlly studied in connection with the or- 
gans of special sense — the nose, the eye, the car. 

OP TSK THIRD PAIR, OR OCDLO-XOTOS HEarCB. 

The motor-oculi nerve arises from the inner side of the erus cerebri, 
near to tlie pons -varolii, some of its fibres passing into the The ttird [i«ir, 
gray substance of tl»c cms. Advancing forward, it di\-idc3 oronJiMnoior. 
into two brandies, one of which supplies the superior rectus and levator 
]}alpcbne, the other tlie internal rectus, inferior rectus, and inferior ob- 
lique. Considering the place of origin, it would be expected that this 
nerve is wholly motor, and tliis is contirmed by experiment. Wiicn the 
nerve is irritated the musclea which it supplies are convulsed, and when 
it is divided they arc paralyzed. Through its connection with the len- 
ticular ganglion, it furnishes motor filaments to the iris. The optic 
nerve, the corpora quadrigcmina, and this nerve together constitute a 
complete nervous arc, and impressions made on the retina occasion mo- 
tioua in the iris. 



k 




334 THE FOUBTH, FIFTH, AND SiaTTU PAIBS, 

or Tin roDttm rjiiB, rATiisTtci, tut ntocntxAK sckxtk*. 
This ncn-e arises from tlie valve of Vicnaaens, near the testU, «&i 
Tliv fourth pair, passiiig oTOund tlio CTttfl ccTcbri, enters tlic orbit, and is di»- 
or pAthctioi. tributcd to the orbital surface of the superior oblique, cr 
trocUIcar muscle, for which it is tlie motor ner\'e. When it ia iiritstei 
that muscle is convulsed. 

or THE rtrm PAUt, tufacul, oa nuaEvca. 

Tlie iiftli nerve Ims a construction so closely analogous to that of ttw 
TTie fifth pair, Bpinal nervcs» that it lias been designated the spinal nerve of 
or tri^wninL |j,(j head. It arises by two roots, the anterior of which is 
the smaller, the posterior having a large ganglion, the ganglion of Gas- 
Bcr ; with this ganglion the anterior root 'is in contact, but not in con- 
nection : it passes forward to tlie inferior ma-TcilUrj' nerve. From tlic 
ganglion three branches diverge, the ophthalmic, the superior maxillary, 
and inferior maxillary, tlic first proceeding from the upper angle of tlie 
ganglion, the second from the middle, tho third irom the inferior aa^ 
This last receives the motor portion of the nerve ; tlie first and uajai 
branches are sensory, the third is sensory and motor also. From tha 
sensory portions the anterior and most of the antcro-latcral portions of 
the head are funu5hed, as also the organs of special sense themselves, n 
far as their common sensation is concerned. Tlic motor branch supplid 
the muscles of masticatioru 

or TOB flUTO PAn, Ott ABDrCBXTKt. 

This nerve arises by several tilamcnts from the upper part of the cor- 
ThsMiihpilr. pus pvTamidalc, near to the pons varolii, and is distribalcd 
or abduceoti!*. ^^j ^\^^ external rectus. From its origin, distribution, and 
from experiments made upon it, it is known to be a motor ncn'c 



n 



lU-trsTKATioNi or ma raiai>, rocBTu, rirrs, axd •ixth rioaa or trEarsj. 

Fig-in. /'i^. 161: 1, chiasm of optic nerves; 2, 

third pair ; 3, nasal nerve ; 4, externa] octdo- 
motor; 5, ganglion of Gasscr; 6, nasal nerve 
and its two limnchea, internal and external; 
7, nerve of obliquus inferior ; 8, ophthalmic 
gnngiion ; 9, ciliary nervea ; a, portion of le- 
vator palpobrae superioris and rectus superi- 
or ; &, rectus intemus ; r, rectus extemus ; d, 
fibrous ring of tlie recti muscles. 

nXTKI Ol THB OKBITAL CATirT. 




MarrMofihaortitL 



I^iff, 162 : 1, 1, optic nerve and globe of tin 



^ 




THE FIFTH KERVE, 



335 



eye; 2,third nen'c; 3, superior branch; 
4, nerve of obliqmis inferior; 5,externtil 
oculo-niotor; 6, ganglion of Gassor ; 7, 
ophthalmic branch ; 8, nasal nen'c ; 9, 
ophthalmic ganglion; 10, short root of 
opht Iiahiiic ganglion ; 1 1, ciliaiy iiervcB i 
12, 6vnt&l ncn'c; a, levator palpcbnu 
superioris and rectus superior; 6, rectus 
interior ; c, obliquus inferior ; </, rectus 
extemus ; e^ ring of the recti muscles. 



DUOBAU or TUB rurn xatvs. 



J^ff. 163: 1, ganglion of Ga&acr ; 
2, ophthalmic ganglion ; *l, its long 
root fumislied by the nasal branch; 
4, short root ; 5, 8}'mpathctic from 
the plexus surrounding the iiiter- 
nal carotid ; 6, ciliary nenea txav- 
craing the sclerotic ; 7, ciliary gan- 
glion ; 8, ganglion of ilcckel ; 9, 
its sensory roots from the Huperior 
maxillary; 10, petrous branch of 
vidian nerve, or motor root of tlio 
ganglion of Meckel ; 1 1, its sym- 
pathetic root; 12, naso-polatinc 
DUcmnortbetfthDcrra gnnglion, receiving at its up|x:r an- 

gle the naso-palatine nerve, and at its inferior the anterior palatine ; 13, 
Otic ganglion ; 14, small superficixU petrosal ; 15, submnxillar)' ganglion ; 
16, sublingual ganglion ; 17, geniculated ganglion; 18, cavernous ganglion, 

aixQuosi OP OAsaEB ahd amacefx pasts. 

Fiff.1^ _fiff, 164: 1, ganglion of Gas- 

Eor; 2, ophthalmic nerve; 3, front- 
al branch ; 4, lachr)'nial ; 5, na^ol ; 
6, opthalmic ganglion; 7, superior 
maxillary ner\*e ; 8, orbital branch ; 
0, ganglion of 3IcckeI; 10, petrosal 
brancli of vidian nerve ; 11, palatine 
nerves : 1 2, anastoraosia of the gan- 
glion of Jlcckel with the ncr^oua 
plexus surrounding the internal max- 
illary nrterj^; 13, posterior and su- 
perior dental nerves; 14, suborbital nerve, its anastomoses wit' 




GukUoh ot a 



TUE FIFTH NERVE. 

and n&sal; 15, inferior maxilhirj*, receiving the motor portion of the fifth 
pair: 10, superficial aiiriculo-temporal nerve; 1 7, buccal nerve ; lH«&«o 
tion of otlier collateral branches of inferior ma^ullary ; ID, inferior den- 
tal; 20, mental nerve; 21, lingual; 22, chorda tympam ; 23, fwia) 
ner\'c ; A, external carotid arlcry ; H, facial artery ; 0, temporal arteiy: 
D, internal maxillary; £^ it3 dental branch; F, middle meningeal; a, 
membrana tympani ; A. glenoid cavity ; f, orbicularis oris ; </, buccina- 
tor; e^ pterygoideus internua;^, pterygoideus cxlernus ; ff, digastric; 
At stemo-deido-maatoid muscle. 

TSB nrtn xeste, tuk oaxclio}! of oasscu beuo KKatoTKn. 

Pig. i«^ _ Fig. 165: 1» oplitbalmic, cut; !, 

sujKiTior maxillnry, cut at both ei- 
tremitiea ; 3, ganglion of Medcd; 4, 
petrosal and carotid branch of lidian 
nerve; 5, abducent; G, nerve of Ja- 
cobson ; 7, superior and posterim 
dental nerves ; S, anterior and sxipe* 
rior dental none; 9, otic ganglion; 
10, gustatory nerve ; II, chorda tym- 
jiani ; 12, subinaxillary ganglion; 
13, anastomosis of lingual with hy- 
poglossal ; 14, sublingual plexus ; 15, terminal brandies of gustator)* w 
lingual nerve ; IG, inferior dental ; 17, mylo-hyoid branch; 18, mental: 
19, indsive nerve ; 20, ganglion of glosso-pharyngeal ; 21, facial, in the 
aqueduct of Fallopius ; 22, hypoglossal ; a, superior maxillary bone; 6. 
cartilages of the nose; c, iutemid wall of tympanic cavity; d^ ptorj- 
goideus intemus musdc; c, buccinator, cut; f^ mylo-hyoid musdc; y, 
port of anterior belly of digastric ; A, stcmo-clcido-mastoid, turned aside 




T1>« flAb iicrvft 



re. !«. 






lUcartuTiOH of tiik tkhmixxl nitAxcnzs or tin 

IKFLltlOR MAX H JJkBT MKttVr.. ' 

F^g, 166; 1, motor and sensory roo^i 
of ganglion of Gasscr; 2, junction of H^H 
tor root with inferior maxilhu'y; 3, auii^^^ 
lo-tcmpornl nerve; 5, bucciil ncrvoj fi, 
pterygoid nerves ; 7, cut branches of tem- 
poral and masseteric nerves; 8, gnstaton" 
nerve; 0, chorda tympaui; 10, Cidol; 11, 
anastomosis of gustatory and inferior den- 
tal nerves; 12, tonsillar branch ; 13, sub- 
maxillary ganglion ; 14, sublingual plex- 



us; 15, anastomosis of gustatory and hypoglossal nerves ; 10, bnmdies 



THE FAC 



337 



i gustatory; 17. inferior dental ; 18, mylo-liyold nerve; 19, Incisive 
■ranch of dental nerve ; 20, bnmcli of mental^ cut ; a, pterygoidcus In- 
cmas ; 6, part of pterygoidcus ejctemus muscle ; c, mylo-hyoid muscle ; 
U portion of anterior belly of the digastric; e, hypoglossal muscle ;y, 
bortion of dubuiaxiliary gland. 

OP Tui: be\t:ktii paih, tiib facul xbrtk. 

This nerve arises from the up|)cr part of tJie groove between the oli- 
rary and rcstitonu bodies, and near the pons varolii. With tiio womnih 
the auditory ner>'e, or portio mollis, it constitutes the seventh P*''- "' f**'*'- 
nerve in the nomenclature of Willis, and derives the name porllo dum, 
tinder which it sometimes passes, from the density and closeness of its 
textturc It supplies all tlic muscles of the face except those of mastica- 
tion, which arc supplied by the fifth ncrvo, those of the palate, the sta- 
pedius, laxator tynqwrni, and tensor tympani ; also the muacles of the ex- 
ternal ear, and some of those of the tongue. The facial is a centrifugal 
nerve If irritated near its origin, there is no sensation of pain; but bu1>- 
Bcqucntly it obtains fibres from other sources, as from the tiflh and tho 
pneumogaBtric. After it has been joined by tliese, irritation is acutely 
felL It is therefore to be regarded as the general motor nerve of tlio 
face, inHuencing the function of respiration through reflex action, but not 
being connected with the function of mastication. Injury of it produces 
paralysis oftlu! parts to which it is distributed, as, for example, the orbic- 
ularis paljwbrarum, causing inflammation of the eye and o[Kicity of the 
cornea, through inability of that organ to iree itself from dust and spread 
the lachryroal secretion over its surface. In like manner, the sense of 
hearing may be injured through loss of control over the muscular struc- 
tures of the ear, and the acuteness of the sense of smell diraudshed from 
Fig.iei. inability to introduce the air in a 

strong current, or the sense of taste, 
if the point of injury be previous to 
the giWng off of the chorda tympani. 
In paralysis of the facial ncn'e the 
muscles of the face become powerless, 
and the countenance, therefore^ dis- 
torted. 

lu-rsnunoN of the vacul xrarc. 

J^ig. 167: 1, trunk of the facial 
at its emergence from the ariucduct 
of FaUopius ; 2, occipito-auricular 
branch; 3, auricular of the cervical 
plexus ; 4, twig of the occipital mua- 




Tbe (kcUI Qcnro. 



838 



THE GL0&80-PUABl7ia£AL 2<ERVE. 



cle ; 5, twig of the posterior auricular muscle ; 6, twig of the Fuptriir 
auricular ; 7, nnastomosis of tlie facial with the auricular of the cervial 
plexus ; 8, branch for the stylo-hyoid and posterior bcUy of the digastric; 
0, tcniporo-faoial anastomosis with tlie supcrticiiJ auriculo-tcmponl U 
the tiflh pair ; 10, tcni^toral rauiificatioiia of the facial ; 11, frontal twigs', 
12, superior palpebral twigs; 13, middle palpebral twigs; 14, inferior 
or motor palpebral twigs; 15, suborbital twigs; 16, enborbital picxuj; 
17, superior buccal ; IS, ccrvico-facial branch; 19, buccal brandies, ana*- 
tomoamg with, 20, buccal nerve of fifth pair ; 21, mental twigs, forming 
witli, 22, mental nerve of fifth i>air, the mental plexus; 2.'t, ccnlal 
branches; 24, transverse cervical branch of cervical plexus ; 2o, parotid 
branches of the superficial aunculo-tcraporal ; 26, {>arotid bmnchcB of tk 
facial; a, frontal muscle; ^, occipital muscle; c, anterior auricular; rf, 
superior auricular ; c^ posterior auricular; f, orbicularis palpebrarum; y, 
zygomaticus major; A, buccinator ; », orbicularis oris; k^mmsBCter; L 
parotid gland ; m, platyama ; n, stj'lo-hyoid aud posterior bcUy of (It- 
gastric ; Of aterno-clcido-niastoid ; jf., trapezius. 

or me ximi rxitt, on oLOMo-rBAjtntcKAL. 

Tliis ncn'c arises by five or ?ix filaments from the groove betwwn 
The ninth polr *^ oUvary and rc.-*tiform Irodics. Its origin may be tmced 
or pio*»i>.iiiiii- to the vesicular substance in the floor of the fourth ventricle: 
'''°^'*^ passing forward, it is distributed to the mucouji membraite 

of tlic base of the tongue and fauces. While in the jugular fossa it 
forms two ganglia, a small one produced by its posterior fibres, and call- 
ed the fi«|K;rior ganglion ; a second, much larger, termed the inferior, or 
ganglion of Andersch. The branches given off by the glosso-pluiryngttl 
arc tlie muacxdar, tlie tympanic or Jncobson's nerve, which is distributed 
to the inner wall of the tympanum and interior ixtrtions of the car; ibe 
pharj-ngcal, which sujipUes the pharynx, and, with branches of the pneu- 
mogastric and sympathetic, forms the phar^-ngeal plexus; the lingual 
suppliea the mucous mcmbmno of the sides and base of the tongue: 
the tonslllitic, which supplies the mucous membrane of the fauces and 
Boll palate, and forms a plexus round the base of the tonsiL Besides 
these, tlie glosso-pharyngeal anastomoses willi tlic facial, pneumogostrict 
accessory, and sympathetic. 

Examined in tlic usual way, the glosso-pharyngeal proves to bo a oen- 
tripctal nerve, having the power of producing reflex motions through the 
nerves of deglutition, its motor influence being chieily due to its cou^ 
nections with the jnicumogastric and accessory. Though thus a sen- 
sory nerve, it is doubtful wlicther it be the only ner\'e of taste, or whcthct^ 
tliat function is not likewise pnrlicipnted in by the lingual branch of tbc^' 
fifth pair. It is certain that section of the lingual does not destroy 



1 



THE OLOSSO-PllAnTNaCAL XEmT!. 



sense of tnste, and also timt tliosc parts of tlie tongiic to which tlie 
glosso-pliaryngcal is distributed prcsont that sense in the most marked 
manner. The inference wliich is usually drawn is that this nerve and the 
Hngnal are both tactile and guatative, and this renders appropriate its 
description in this place rather than among the ncn'es of special sense. 



F;g.\0^ 




Tb« sl'»K>-|'^*0'<m<^^ 



pathetic; ID, hypoglossal, cut. 



n4.08TiuTio» or Tar, cLoano-piuRTaoEAi.. 



J^lff. 1G8: 1, origin of the glosso-|iharnigpal 
between^ 2, tlie pneumogastric, and, 3, tlie facial ; 
4, ganglion of Andcrsch; 5, pharjTigcal branches; 
6, anastomosis of tlic glosso-pharyngcal with the 
lingual branch of tlie facial ; 7» application of the 
spinal to the superior ganglion of the pneumo- 
gastric; 8, branch of jugular fossa; 9, plexifonn 
ganglion of par vagum ; 10, carotid brancli ; 11, 
superior larpigcal ncr\c ; 12, external lar}*ngcal; 
13, inferior or recurrent laryngeal; 1(, cervical 
branch of the spinal; 15, bulbar branch of same 
nerve ; the union of these forms a trunk which 
divides into two brandies ; 16, external branch ; 
17, internal branch ; 18, cervical portion of syra- 



ng- lo. 




UIAGUAM or CLOSSO-PniBTSOElU 

J^ff.lGO: 1, facial; 2, glosso-pharyngeal; 3, pneumo- 
gastric ; 4, spinal ; 5, hypoglossal ; 6, superior cerWcal 
ganglion ; 7, 7, anterior branches of the two first cervical 
pairs; S, plexus cnvclo|)ing the internal carotid artery; 
9, Jacobson's nerve ; 10, its anastomotic Inranch with the 
carotid plexus ; 1 1, small deep |ietro5al, which passes into 
the great sujierficial petrosal; 13, otic ganglion; 14, uiuis- 
toniosis of gloss o-pluiryngeal with lingual branch of the 
facial; 15, anastomosis of gIosso-pharj*ngpal and pneumo- 
gastric; Il>, anastomosis of the pharyngeal of the glogso- 
pliaryngeal with that of the pneumogastric and of the 
spinnl ; 17, auricular t>vig of Arnold ; 18, application of 
the trunk of the spinal to the superior ganglion of the 
pneumogastric ; 19, anastomosis of intenial branch of the 
spinal with the ganglion of the trunk of the par viigum ; 20, anastomosis 
of pneumogastric and hyjioglossal ; 21, anastomosis of lni>oglos8al with 
the loop formed by tirat and second cervical ; 22, 22, anastomosis of the 
two first pairs with the cervical ganglion ; 23, i>haryngejxl plexus; 24, 
laryngeal plexus ; 25, anastomosis of the external branch of the spinal 
with the anterior branch of tlic tJiird ccrvljial pn\r. 



DlHgnuu of ktuffto- 



S40 



THE PSETMOGASTMC XERTE, 



or THE TEXTR PAIS, TIIK PAB VAODM, OR PJfKCHOGASTKlC XCRTX, 

The pncumogastric nerve arises hy six or eight tilamcnts from tU 
groove between t)»e olivary and rcstilorm bodies below the glosao-phip 
ryngcalt and, like it, may l>c traced to the vesicular material of the fiotf 
Th«tcntii Air °*^ ''^*^ fourtli ventricle. It tirst presents a small gangUoQ. 
or i>neunH:e»- and BOon after a second, nearly an inch in IcngUi, called the 
plexus ganplifonnis. The nerve then descends the neck in 
the sheath of the carotid vcsscU, and in its course dUTcrs on the nglit 
and left sides respectively. On the right side it passes between the sob- 
cla^nAn artery and vein, descending toward tlic stomach and solar plexus 
on tlio posterior portion of the oesophagus ; on the led it enters the cbesi 
nearly parallel with the left subclavian, and jiasscs to the stomach uvi 
solar plexus along the anterior portion of the irsoiiliagus. 

The cliief brandies of the pneuniogastrie arctlie auricolar, thcphaiyn* 
gcal, the superior laryngeal, the cardiac, the inferior laryngeal or recor- 
rent, the anterior pulmonary, the posterior pulmonary, the cesophsged, 
and the gastric. 

The pneumognstric presents several plexuses in its coarse;, and, e^TO 
wlien distributed on the stomach, cxluhlLs Hat, mcmbraniform ganglii. 
It supplies three great classes of organs : 1st. The digestive, as the pba- 
vyns, oesophagus, stomach, liver; 2d. Kespiratory, as the larynx, tracho, 
lungs ; 3d. Circulatory, as the heart and great vessels. It associates i1- 
self intimately with the sympathetic, and aids it in forming se\'eral gretl 
plexuses. 

At its root the pneumognstric la sensory, but in its trunk it posaesses 
n double function, arising from its intermingling with other nerves, as the 
spinal accessory and sympatlietic- Though the trunk, if irritated, gives 
rise to pain, we arc not, under ordinary circumstances, conscious of iaili* 
cations, as, for example, in the act of breathing, in which wc do not pei- 
ceivc the necessity of respiration, except the access of the air be too long 
delayed. The pharyngeal branch is the chief motor nerve of the pharynx 
and palate. The superior lar^ngc^l is the sensory nerve of the laryns. 
the inferior laryngeal being the motor. Considered along witli tl»c f^n- 
nal accessory, the pncumogastric presents an analogy to a spinal nerve; 
tlu' accessory constituting the anterior or motor root, and the pnctuno- 
gnstric, with its ganglion, the sensory root. 

The pneumogastric nerve was formerly regarded as taking an influen- 
tial pai't in the action of the stomach during digestion. The precise na-— 
tnre of its agency in this resjxjct has been already alluded to. In addi— * 
tion, it may be remarked that probably through tiiis nerve is the 
tion of hunger conveyed to the mind. 





n-j. i;ol 



J^^. 170 : 1, 1, 1, the pncumogastric nerve ; 2, anastomosis of it witli 
the hypoglossal ; 3, anastomosis of plexiform ganglion with internal 
Iranch of the spinal; 4, ])haryngcal, passing in front of the internal car- 
otid artery ; 5, superior hiryngeal, l)ehin(l the internal carotid artery ; 6, 
external laryngeal; 7, laryngeal plexus, formed by external ]ar}'ngeal 
and great s}Tnpatlictic; 8, superior cardiac ; S), middle cardiac; 10, 10, 

inferior laryngeal, or recurrent, 
forming a cnnc round tiio arch 
oftiicaorta; 11, pulmonary gan- 
glion , 12, its anastomosis with 
the great sympathetic ; 13, |K)S- 
terior pulmonary plexus; 14, 
oesophageal plexus; Ij, curves 
formed around the a>su]>liagU9 
by tJie right and left jnieumo- 
gastrics , I G, cL'sophagcal strand 
traversing the diaphragm ; 17, 
plexus formed by the strand 
upon the anterior lace of the ear- 
diac end; 18. branches for the 
great end of the stomach; 19, 
branches for the small curva- 
ture; 20, branches for tlie ante- 
rior face of the stomach; 21, 
lu.'[tatic branches connniiigling 
with the hepatic plexus of tlic 
great sympathetic, and raraify- 
ing in tlie substance of the liver, 
22, glosso-pliarjTigeal . S.*?, its 
lingual brancli , 24, pliaryngeal 
braneli ; 2.'j, brancli for ihc sly- 
lo-pliarynge^d muscle; 2(>, spi- 
nal; 27, internal branch, aiding 
to form the jiharyngeal ncr\'e ; 
28, exteriinl lirnnch ; 29, tivig 
of external branch anastomos- 




Tlw lef. iinriimoeBttric atrtt. 



' ing with the third eervic<'U; 30, anastomosis with trai>ezian branth of 
tlie fourth cenical; 31, cen-ical portion of great sympathetic; 32,32, 
thoracic portion ; a, thyroid body ; A, trachea; /*, left lung, drawn to the 
right ; dj liver, raised ; tf, oesophagus ; f, great end of the stoinacli* 
drawn lo the left; ff, arcli of the aorta; the carotid, and subclavi.m nr- 

1 1 cries, cut. 



842 



THE fiPIXAL ACCKB«ORT KER\T. 



F^ITI. 



MnidMU-)' (WisthL 



IIXCSTttATlOX or rtTLyoXABT <tA3IOLLi. 

lug, 171 : 1, 1, pulmonary ganglia ; 2, median lau- 
tonioBcs of tliese ganglia at the posterior face oftW 
tracliCA, and origin of the bronchi ; 3, left kryngfal 
nerve, aiding to form iho bronchial plexus ; 4, anw- 
tomosea of the two pncumogastrica on the postcnoi 
faoo of the oesophagus. 



* ILLCSTKATlUN OF IMFLXIUK l-iBrxa IU.La, ATCTCRIOft rUUIOXAlIT, JISO CXltDUC riXXO. 

lig. 172, 1, 1, pncumogastric ; -, 2, superior lar^-ngeal ; 3. 3. extci- 
rtff. ITS. nal Uiyngeal j 4, superior cat- 

diac nerve ; 5, 5, middle canliai: 
ncr\c8 ; G, inftrior cardiacs ; J, 
cardiac ganglion and plexus; S,!i. 
nerves from this plexus sunoiuii]- 
ing t!ic coronary plexus ; 9, 9, «- 
tcrior pulnionaiy plexus ; 10^ 10. 
inferior lai^-ngeal: tlie left em- 
bracing the arch of the aorta, the 
right the subclavian arler}', Iwtlt 
go to the pos^tcrior face of ibc 
lar}'iix ; 11, tracheal braiKhcs: 
A, pulmonary artery ; B, its Ici't 
branch ; C, its right branch ; U 
arvh of the aorta ; £, fibrous cord 
Th« infariar uirnpwu. arising from obliteration of tlw 

ductus arteriosus ; F, left subclavian ; G, G, left immitive carotid ; U. 
brachio-cephalic trunk, cut to show cardiac nerves ; I, vena cava eui*- 
rior; K, left coronary artery and vein; L, right coronary artery aod 
vein , rt, os hyoides ; i, proji*cting jmrtlou of the larj'nx ; c, trachea; A 
♦h}'ro-hyoid muscle; c, c, crico-thyroid ; f^f^ scalenus anticus; s^,J. 
th}Toid body; h^ />, diaphragm; i, U pericardium, cut away. i 

or Tuii ELKrrxrn paib, or bh^al acceuokt jncara. 

Tlio spinal accessory arises by so'cral filaments from tlic side of thfc 
Th H r It) sp'"3i cord, as low as the fifth or sixth cervical ncr\c In 
■■air or »(>iii«i its Upward cctu'sc it communicates with the posterior roolf^ 
ncwMor.v. ^j. j]^^ j.j.gj (.(,rvif.,-il. It tticn divides into two branches, th*> 

smaller joining the pncumogastric, the main tniiik jiassing onward, an^ 
being GvcntunUy distributed to the tra}>ez!us nmsclo, and also furnisMzi^ 
supplies to tlie stcmo-mastoid. 

27jc spinal accessory is a motor nerve, as appears from the ttsnal c^S-^ 



J 



THE nVPOGLOSSAL AND PHRENIC KERVE3. 



8^ 



dencc of irritation, and aUo from its origin and distribution. Ita action 
15 not essential in ordinary' or involuntary respiration. In volontary res- 
piration it is brougiit into play. 

or Tltl: TWELFTn pair, or UTfOCLOSSAL NKRrR. 

This nerve arises in tlic groove Ijetwecu tlic p/raraidol and olivary 
Itodies, Ly 8 or 10 filaments, wliicli are collected into two Theiweifih 
bundles. It next passes forward and crosses inward, piir- p»if, or livpo- 
snes a course wliicli is concave upward, and supplies the *"' "*" ' 
igcnio-liyoglossus and muscles of tlie tongue generally, giving off tlic 
jlfjllawing brandies in its course: tlie descendeus noni, the tliyro-hyoid, 
•nd filaments connecting the gustativc nerve. Il also anastomoses with 
ithc pneumogaatric, spinal accessory, first and second cen-ical nerves, and 
wym pathetic. 

The h}-poglossal is the motor nerve of the tongue, irritation of it giv- 
ing rise to movements throughout that organ, the lingual braucli of 
the fifth being the sensory, Tlie hyjioglossa! causes the musel'":^ of tlie 
fteck to aid in the movements necessary for articulutc speech. 

ILLCSTa»Tl'>;ff OF THE IITrOOLOSSAI. KZaTt. 

.^f^. 173: 1, medulla oblongata ; 2, glosso-pharyngeal ; 3, pncumo- 
Fis. IT3. gastric ; 4, aui>crior laryngeal ; 5, spi- 

nal ; G, first cervical |>air ; 7, second 
pair; 8, third pair ; 9, fourtii pair; 
10, lingual; 11, origin of hypoglos- 
snl; 12, anastomosis of h^'pogloasal 
wi(h first cervical; 13, anastomosis 
witli nenous loop of two first cervl- 
cals ; 14, descending branch of hy- 
I ^^/^S^^^^^S^^^" poglossal, anastomosing with, 15, dc- 

^^ '^llf^K^K^^' scending brandies of cervical ])lc:tua : 

^B ^^^^ 16, twig of th}TO-hyoid musde; 17, 

^^ Th^bTpofffc—x^^rr* Lmnches of hyoglossus ; 18, rccur- 

'rcnt branch of stylo-glossus; 19, bnuiclies of gcnio-hyoid ; 20, plexiform 
llronchcs of hypoglossal ; 21, anastomotic branch with the lingual; 22, 
jlraiich for submajtillary ganglion ; A, vertebral arterj- ; B, external car- 
lotid; C, Ungual ; D, tem^^iorul ; K, internal maxillary ; a, [wrtlon of the 
(condyle of the occipital bone ; by median section of atlas ; c, stj'loid pro- 
; rf, Htylo-glossus ; c, atylo-pliar^Tigeus ; f^ hyoglossus ; y, genio- 
/*, ptcrygoideus extemus ; i, ptcrygoidcus intcmua. 

OF THE PlIBCKIC ICERTE. 

Although the plu^nic, or internal resjuratory nerve is not strictly in- 






The pbreoio cluiled in llie group now uii^cr conai deration, yet, coi 
"«"*• its iinportntit tomicction with the motions of respiration, it 

proper to describe and illustrate it here. 

Il arises from the tbinl and fourtli cervical nerves, aided by a hnach 
from tliB iiAh, or from tlic brachial plexus, and from the sympathetic. 
Id its descent it communicates with the lower cerWcal ganglion, enlen 
the thorax l>ctwecn the Bubclavian vein and ar1cri>% and, pasi^ing aloitg 
the side of the pericardium, descends to the diapbragn), the right phrenie 
being pcr])cndicular, and the loft running obliqnely round the apex of tbfe 
heart II is distributed, for the most part, to both faces of the diaphtagm, 
sapcrior and inferior. It is the motor nerve of the diaphragm. 



rt> iTi. 



iLLcmuTiox or TttK piiasxic snEBvm. 




i 

i- 



nu pbniUo nun't. 



I'lff, 174: 1,1, root of the phrem! 
nerve, funiislied by the fuurtii cervi- 
cal ; 2, 2, roots ftom the hraciiial 
plexus ; anastomosis of this nerve 
with branch of the subclavian ; 4, 
anastomosis with the inferior c»- ' 
\'ical ganglion ; 5, 5, curve of the 
li^*pogloasal, cut, sending a twig to 
the phrenic nerve ; 6, 6, ]>ericaniiac 
branches of the phrenic nerve; 7, 
7, branches to the superior lace <^__ 
the diaphragm; 8, 8, branches tfl| 
the inferior face of the diaplimgra; 
9, anastomoses of these branches 
with, 10, tiie solar plexus ; 11, 
transverse communication of the 
plircnic ncn'cs. ^j. 



or niB OQEAT evairATUETic serve. 
Under the designations of sympathetic, visceral, trisplanchnie. gangli- 
P "tio a **"*'^ intercostal, or nr.no of organic life, passes a series of 
■tncturaortlH reddish or gray ganglia, intertx)nnccted by nervous strands, 
•jinpftUMUc. extending along eacli side of the vertebral column, from the 
head to the coccyx, communicating with all other nerves of the body, 
and distributing brunches to the internal viscera, or organs of invoJunla- 
Tj function. These ganglia arc less numerous than the vertebra*; the 
chain on each side communicates witii its colleague through plexuse s, 
and the ganglion impar is the common uniting point on the coccyx b<l^| 
low. By f»omc it is supposed that the ganglion of Ribes, and by othei^^ 



that ih& pituitary body has the same function in the cranium alMv^ 




CONXEcmON OP SYSIPATUETIC ANI> SPIXAU 



345 



here Bpoken of as nervous strands nrc perliapa more coixcctl/ 
■tion3 of tb« gtuiglia tiieiuaelvcs. 
J ongin of the sympathetic lias been long a subject of dispute, some 
»ng that it is n special system, of which the ganglia ore origin ofibe 
ny independent centres, rstablisiiing incidental commu- svn»H>iiei»c- 
ms witli the cerebro-spinal ; others, that its origin is in the internal 
B, and its termination in the eerebro-spinal system, this opinion be- 
ipportcd by tiie aUenvd facts thnt the Bvnipathetic, in its dcvoloi>* 
appears before tlic other parts of the nervous system, and simulta- 
\y vitli the eplanehnic organs, and that it lias been found in mon' 
without a brdin or spinal cord; others, again, sup]wse that it orig- 
from the roots of tlic ccrcbro-spinnJ system, and terminates in tlio 
)r organs. Regarding it in this light, some have impntcd its origin 
the spinal, and tifth and sixth cranial conjointly; otlicra havclim- 
; to thfl two latter. 

& pncnmogastric nerve aids it in forming throo of its plexuses, the 
ngcal, cardiac, and solar. In certain respects the pncu- Ktiiuiopj of 
rtric and sympathetic Bccra to cxiiibit a reciprocal dc- f/J^BnlJ'srm- 
nent, in some of the lower animals tlio former pre- i>«Uieiic 
lating over, and supplying the place of the latter; and this rcplace- 
it is said, goes on in the descending series until, in (lie ccphalopo- 
noUusks, the sympatiietic has disappeared, and the pneumogastric 
its place. 

J^tff. 175 illuBtratcs the relation 
of the sympathetic and spinal nerves: 
Cj c anterior fissure of the spinal 
cord; a, anterior root of a dorsal 
spinal nerve ; jw, posterior root, with 
its ganglion; a', anterior branch; j/, 
posterior branch ; *f, syinjiatlu-tic; tf, 
its double junction with liic anterior 
brancli of the spinal ncn*c by a white 
and a gray filament. 

The Bympathelic chain therefore 
establishes connections connection of 
with the ccn=bn.-,i,inal ri^rj'^-. 
Bystem, Kaeli spinal <«m. 
nerve is brought into relation with 
it through two strands, a tubular or 
white, and a gelatinous or gray. 
The tubular or white strand may be 
regarded as actually arising from the 
spinal cord, and couftvftlw?^ cs? \ftQ,V«t 
and sensory fi\amcT\V&. \\ w;^«> >^* 



rtj. im 




4Mton aflhn •jmjfmthctte mad i^lnal. 



L 



MS 



THE GREAT SYICPATIIETXC. 



way to the ganglion of the sympathetic, passes over and through it, ils 
fibres conjoining themselves ivllh. gray ones, which they liave gathered in 
the ganglion. The gray or gelatinous root is to be viewed as baring its 
origin in tlie ganglion of the sympathetic, and sending its fibres chiefly 
to tlie ganglion on the posterior root of the spinal ner%-e, but few of then 
doubtfully communicating witJi the anterior root. The tibres which aoem 
to enter iho cord ore probably for the supply of blood-vessels. Kadi of 
these sympathetic ganglia is, therefore, a nen'oua centre, sending forth 
strands in three directions: 1st. To join the spinal tibrea in their datn- 
butiou ; 2d. To tiie spinal cord itself, or chiefly to the gangUa on the po«- 
tcrior roots of its ner\'cs ; 3d. To tho next sympathetic ganglion abo\-e. 
Srmpiiiiietic In the various plexuses of the sj-nipathctic, vesicles aie found. 
plexuMs. j[rom which gray fibres seem to originate. The branches which 
supply the viscera constantly form plexuses ; the arieries are surrounded 
witli such a net-work. The splanchnic ganglia, with their interconnect- 
ing strand5, and supplies from the cercbro-spinal, give riso to four great 
plexuses: tho pharyngeal, the cardiac, the solnr. and the hx-pogaatnc 
The iirst and last of lliese arc in aymuielrical jiairs; the other two an 
single, and placed on the median lino. 

l''rom its c*on8truction the sympathetic can not be regarded as an iso* 
Phv>ic«ien«-t« ^^^^ or self-acting system, since oil its hranclics contain 
of Hvmiiitheiic (ibrcs derived from the cerebro-spinaL In function it mtut 
guitf la. therefore Lc adjuvant to tliat system, and it must lie adndt- 

ted that the motor and sensory qualities of the included spinal fibres, ac- 
cording as they have been derived from the anterior or posterior coluniBS 
of tho cord, ore continued in their association with the sympathetic. 
Ilence, iu so far as being a compound ner\'e, it possesses bolb those func- 
tions, and this conclusion is corroborated by such facts as those of the 
distribution of tho sympatlictic both to muscular portions, as to the heat 
and also to sensitive ones ; by the circumstance that tho intestinal ontl 
from tho stomach to the cud of tho colon receives its nervous supply 
from this source alone. Kxperiments on the sympathetic ganglia cstalh 
lish a similar conclusion, irritation of the cadiac ganglion, for instance. 
giving rise to incre-ascd peristaltic motions, and pathological observation 
fumishiiig like evidence as regards the sensory function. Compared 
with otlier nerve trunks, tho sjTnpathetic is much less active in those re- 
spects, a Iiigh irritation of the parts supplied by it often beijig rcquireii 
to cause pain, and, in like manner, its motor fibres arc Httlc under tho in- 
iluence of the will. 

The sympathetic transmits sensations so tardily that it has been sop- 
poac<d that one office of its ganglia is for tlio purpose of cutting otT aacb 
impressions ; and, in like manner, wlien motor fibres of the cercbro-spi- 
tml Bj'stem pass through its ganglia, their conducting power a]ipears 1t> 



I 



I 



THE GREAT tSTMPATHETia 347 

Ix imiiaircc]. There doca not seem to be any decisive proof that any of 
tlie fibres of the syniimtliotic, properly s|>eaking, are molor or sensory, or 
tliat its ganglia product*. rcHcx action, the agency ivliich it exerts in these 
respccta on the muscular structuTo of tlie heart, blood-vessels, digestive 
or urinary Cleans, being due lo the associated cerebro-spinal fibiva. 

In thi.-4 manner, by its distribution to the arteries, the syiupalhetic, ns 
« compound nerve, exerts a power over the passage of the blood tlirough 
them by influencing their contractility, and thereby their diameter. In 
virtue of this, it therefore affects the rapidity of secretion, and also r^u- 
JAtea the rate of nutrition. The entire digestive tract, with its dependen- 
cies arc thus brought under its iiillucnco, the salivary glands, pharynx, 
OBSopltagos, stomach, intestine, nasal, Lroncliial, and pulmonan,'^ sur* 
fiu^ee, etc. 

The ^-icw of the function of ganglia presented on preceding pages is 
strongly supported by the mechanism and phenomena of the itg„„-jj. .„ 
sympathetic ncnx. Its gangha permit tlie influence passing reaurvoin cf 
along the nervous cords to escape therefrom into new chan- ^'^' 
ttels, and also retain and store up nervous power. They become, there- 
fore, magazines of force, and are hence capable of sustaining rhythmic 
movements. Kvcn after organs have been cxBCctcd, they will still exhib- 
it, under the inllacncc of the»e ganglia, tlicir accustomed motion, as is the 
case witli the Iicart, which, in some of tl:c cold-blooded animals, will con- 
tinue its contractions for majiy hours alUr it has been cut out of the body. 

I tliereforo rt'gard the s^-ropathctic system as having for one of itb 
main functions the cquali^auon or balancing of the nervous Conclusion 
force, storing up all transient excesses of it, and furnishing {".^'"^^Ik 
ail transient dclicJencies. As in a mechanical contrivance, lyiiipatbetic. 
in which the prime mover works in an irregular way, the fly-whccl har- 
monizes all such variations, storing up or supplying power as the cir- 
cnmstances may require, so dues this complicated apparatus act in the 
mocbanism of innervation. And it is wortliy of remark, that some such 
MTangement would seem to be necessary, since the organs of digestion, to 
whicli the sympathetic is so largely directed, are periodically in activity 
and pcriodicjiIJy quiescent. 

It is to be greatly regretted that the term sympathetic lias been sp- 
plied lo this important nerve, since that tenn, as defining function, has 
led to the promulgation of theoretical views which liavc exerted an influ- 
ence lo the disadvantage of the progress of physiology — views which will 
not bear the test of anatomical criticism, and which are therefore incor- 
rect. It is always much better to give designations in allusion to struo- 
tore or position than to function, especially where the function is doubt- 
ful. For this reason, the title of intercostal is much preferable lo that 
re of organic life, and trisplan clinic better than syTO^tVw,v.v:. — (aai 



348 



THE OBKAT fiTMPATIIETTC. 



imposing hnt mj-stcrions rpithet, wliirh hoH \iccn a sonrrr of injury to 
the science, and which it would Ire well even now to replace by sudu 
tcnn B» vincular or moniliform ncnc, or same title of eqnivalcnt import. 



XLLrmuntKi or tub great tmrATurnc. 



Pi9. i;& 









'¥ i 



J^iff. 176: 1, globe o( the eye, 
dissected so as to show the ciliary 
nen-es ; 2, branch of the inferior ob- 
lique and tlic motor root of the opb- 
thnlroic ganglion; 3,3,3, the tlvM 
branches of the trifacial, in connec- 
tion with most of the cranial gaa- 
gUa, that is, with, 4, ophthalmic giih 
glion, 5, sphcno-palatinc, 6, otic, 7, 
submaxillaiy, and, 8, sublingual: 
9, external motor ocuU; 10, facial 
and its nnnstomoses with the splw- 
no-palatine, and otic ganglia; 11, 
glosHO - pliaryngGol ; 1 2, 12, ri^t 
pneumogastric ; 13, loft pncum»> 
gastric; 14,s|iinal; 15, hj-]K)gIos- 
sal; 13, 16, cer\'ical plexus; 17, 
brachial plexus : IH, 18, intercnstal 
nerves; IS), 1!J, lumbar plexus; 
20, sacral plexus; 21. snpcrior cer- 
vical ganglion, furnishing two caro- 
tid branclu's, forming the carotid 
plcxns around the artery of that 
name, and tVom which arise the 
anastomoses with, 22, iicrvo of J*- 
cobson, 23, carotid branch of vid- 
ian ncne, 24, external motor oc- 
uli, 25, ophthalmic ganglion; 26, 
twig for the pituitary gUind; 27, 
anastomosis of superior oenieal 
ganglion with the tirst cerrictl 
pairs; 28, carotid and phaiyngwl 
branches; 29, pharyngt^al and in- 
tcrcarotid plexus ; 30, laryngi«l 
branch, anastomosed with tlie external larj'ngcal of the pneumc^astric; 
31, superior cardiac ner\*e ; 32, strands of junction of the superior cenn- 
<'al gnnghon with, 33, middle cervical ganglion : among the infernal 
brandies q{ ihe latter are, 34, the aivaalomQUc. mlh-. 33, the recuirent 



The (fre«t frnpftthHle ncrv*. 




THE ABDOMmAL PLEXUSES. 



$49 



J6, middle cariliac nen'c ; 37, strand of junction of middle cervical 
lion with, 38, inferior ccr\'ical ganglion ; 40, twigs furnislicd by in- 
; oen'ical ganglion around the subclavian and vertebral arteries ; 41, 
[omotic branch with the lirst intercostal nerve; 42, cardiac plexus 
ganglion ; 43, 44, nccondary plexuses of right and left coronary ar- 
i; ftom 45 to 4l), thoracic ganglionar}' chain ; 47, the great aplanch- 
nvcraing the diaphragm, and going to, 48, semilunar gangUon ; 49, 

splanchnic; 50, solar plexus, receiving, 51, anastomosis of j>nou- 
istrlc,02, phrenic nerve; 53, gastric coronary ; 54, hepatic; 55, splc- 

56, superior mesenteric, enveloping the ai'teries of those names ; 57, 

plexus ; from 58 to 58, lumbar ganglionic chain ; 5Q, lumho-aortio 
IS, presenting two enlai^nicnts, one, GO, above, the other, Gl, below 
ifhrcation of the aorta; G2, spermatic plcxns; G3, inferior mcscntcnc; 
ijpt^astric plexus ; (>5 to (J5, sncral ganglionic chain ; tiG, terminal 
rgeal ganglion; A, heart, slightly turned aside to show t]ic cardiac 
a» ; B, arch of tho aorta, also drauii aside by hook ; C, iunominata ; 
tbclavian, cut, to show inferior cervical ganglion ; E, inferior t]iy« 
I F, |)ortion of external carotid ; G, internal carotid ; H, thoracic 
>; I, abdominal aorta; J, primitive iliac; K, intercostals ; L, pul- 
uy artery, of which tho right branch is cut ; II, superior vena CJiva, 
it its origin; N, vena cava inferior; (), pulmonary veins; tf, lach- 
1 g^and ; &, sublingual gland ; c, submaxillary gland ; d^ thyroid 

; 0, trachea ; y, oesopliagus, going to. ^, the stomach ; /j, several in- 
kal loops with superior mesenteric plexus ; i, transverse colon ; j^ 
did dcxure; ^', rectum; /, bladder; ?n, ureter; n, prostate; 0, vc- 
■'^l^ '"- sieula scminalis ; ^7, vas deferens ; (7, sperm- 

atic cord ; r, r, diaphragm. 



TUK AODOHIKAt. TLEXUKEg. 



•uIraI pUr 



J^i^. 177: 1, 1, 1, 1, portion of the right 
and left ganglionic chain ; 2, coccygeal gan- 
glion ; 3, median anastomoses of the two 
sacral cords ; 4, 4, great splanchnic, right 
and left, traversing the diaphragm, and go- 
ing to, 5, 5, BcmilnnRr ganglia ; 6, solar 
plexus ; 7, splenic plexus ; 8, hepatic plex- 
us; 9, coronary plexus of stomach; 10, 
anastomoses of tho two pncnmogaatrics, 
right and loft, with solnr plexus and gastric 
coronaiy; 11, dia])hraginatic plexus and su- 
perior capsular; 12, anastomoses of these 
two plexuses with the plircJiic ncr\-e; I'J, 
middle capsular plexus ; 14, inferior ca^sa- 



350 



THE SOLAR PLEXUS. 



lar plextig, coining from, 15, renal plexus; U>, 16, lesser splanchnic*, 
traversing tlie diaplimgm ; 17, puperior mesenteric plexus ; 1^. spcnn- 
Atic plcxQS, arising from thrco eoorcca, the renal, lumbo-aortic, and hrpo- 
gastric; from 19 to 19, lunibo-nortic plcxos; 20, 20, its bifurcations; 
21, inferior racsCDleric plexus; 22, 22. its anastomoses witli, 23, 23^ 
hypogastric plexus on cacli side ; 24, 24, sacral plexns ; a, diaphragm, 
cut ; A, portion of stomach and os.sophagus ; r, spleen ; rf, kidney and it« 
supra-renal capsule ; <?, testicle ; /', ureter, cut ; A, A, aorta. 



mi: SOLAR 1>IAKC». 



Fig* 178: I, eolar plexus, furnishing, 2, hepatic plexus; '■^, gastric 
coronary plexttJ*, and, 4, splenic plexus ; 5, anastomoses of right and left 
pneumogastric with the solar plexus and gastric coronary ; G, brandies 
of pneumogastric going to the liver ; 7, plexus of biliary ducts; 8, origin 
of superior mcsenterie plexus; 9, renal plexus; 10, capsular plexus; 
11, 11, spermatic plexus; 12, commencement of lumbo-aortic plexoi; 
1 3, portion of inferior mesenteric plex-us; a, the liver, raised; ^,lhcs1oro> 
ach, cut at its great end; c^ the spleen; </, the kidney; r, kidney, cut; 
f^ supra-renni capsule ; g, g, ureters ; . _ 'V- 1"- 

At duodenum ; t, i, pancreas. 

riff. 179. 



It u n II 

Tbs loUr pitxm 




Tlip mcMnlBrk idanHB 



irruBtoR MEanrrBuc xm ntrcRios ue«EinxRic puexcs. 

J^ig. 179: 1, snperior meacntcric plexus, surrounding the divisions of 
the nrtpry of the same name, and offering many flat ganglia ; 2, portion 
of inferior me^ntcric plexus; n, ccecum and appendix vermiformis ; A,i, 
transverse colon ; c, portion of small intestine. 



I 



351 



CHAPTER XVHL 



OF THE VOICE. 

I aft\e Voir*. — Oimparatirr. Physioloyy t^f Sout, Sony, Vtfvx. — Diatmetion bettpoeti Sonp 
SpetrA. — T%e Larynx, ami its Artion in Siayutff. — MuIIctm JCr/ttfOiOtioa ^f the Adion of 
I'uncf/ Oryun*. — Sjieatiiiff Aniaiata oni/ Mudniteji, 
KifMfv qf" W'ttni* and thtir ooattitmatt Soundi, — V<nvclt and C'onvitaiU. — WlMt/teriny, — (Tm 
<fih€ Viiict of AmmaU, 

' tjaBtgimvjt*: tJicir Daration^ Ch v aete r , IIittorif.~~Rttfi*trj g^ Somiidt hg Writing and I\mt- 
^iff,—MiimealSiynM.~-Alp!iahetie Writing. 

Fob the produciion of tlic sounds nccesBary for intercommuuication 
nong the higher animala, anil ]iarticularl)^ for tho spt^ech of Voice mnwt 
nan, it might he supiwscd that some complicated and elah- „7^aru of 
Ofate contrivance must needs he resorted to. This object is, lespirkUon. 
however, ucconipHshcd by merely eiHployiii|*, on its escape from the sys- 
tem, llic waited product of rcejiiratiou, tho breath, which, as it issuca out- 
through the respiratory passfigcs, sets in motion a simple niccban- 
tlit^rchy originates nil tlic exquisite modulations of son^, and 
itnpressive utterances of 8[>ccch. Is it not to be admired (liat 
iO&i oiit of dead and dismissed matter, results of so high an order, ma- 
t' ^ and meutally, arc obtained? 

. . - -L might bo tenned tlie com]>arativc physiology of the ^'oicc is very 
ioiple. It appears first in invertebrate animals as a mo- » . 

lotonoos noise or cry, wliieh gnidnally, in higher tribes, be- phy%ia\o?yot 
somes more varied in loudness and note. It is worthy of ^ * *'"*^' 
cmark that, in the different stages of his existence man himself furnishes 
|m UJuitration of this course. Voiceless before birtJi, with a piteous or 
monotonous cry in early infoncy, articulate speech and song are tiie re- 
mit of education, and through these the power is cventUAlly gained of 
expressing the most refined emotions and the most elevated ideas. The 
lolitary bcU-like sound which the nudt branchiate gasteropods emit, thus 
lirodnces, by its successive improvements, a wonderful result at lajit. 

Among insects tlic modes of producing sounds are very various, some 
cfTccting it by percussion, some by the friction of homy or- p^j„pjj„a ^ 
gans. In otiiers, the extremity of tho traclicn, through riuiimcntwy 
vhich the air escapes, ia accommodated with vibrating mem- *°^ 

According to Uurmcistcr, the contractions of the muscles of the 
which are brought vigorously into action during flying, ocoaaion 





BUDIMENTARY SOUKDS. 

an alternate prcssoro and rdax&tioa 
upon the tracheal tubes. The sir, 
thus ^>assing in and out, throws iiiio 
vibralion tlic valves of the spincle, 
which, as seen in I^ig» 180, aro los- 
peiidcd upon a dozen or more flcxiUc 
supports ; but their Ijco edges, ap- 
proaching witliin a certain distance of 
each other, are throirn into quick vi- 
bnilion by the passing current, in the 
same manner as is tlic vibrating spring 
ot' the accordeon. These vibrating 
plates of insects ore the rudiments ol 
apirMi««rb»eei. ^^.j^^^ ^,-^ bccomc tlie perfect vocal ap- 

paratus in man. Again, in others, the swiftljr-rccorring beating of the 
wings produces a sound, as, for example-, in the musf|uito. Among vcr- 
tebratcd animals, tiiosc which breathe the air arc vocal, nearly all tuhei 
Sonnds nf np. bcing mutc. From lishcs, as we pass upward, the sound 
iUc» and liirUs. j^^^ jj^^ jnstnimcnt which makes it increase together in com- 
|>!cjcity. Through a simple chink, tiic air expelled from the respiraloi; 
sacs of snakes, by the contraction of their ab<lomiual muscles, issues 
forth as a mere hiss, the sound being increased in the frog by tJio devel- 
opment of resonant cavities. From these simple noises we are condact- 
cd to the musical notes of birds, some of which are of exquisite purity 
and sweetness. Iji these, tlie vocal glottis is situated at tlic bifurcation 
of the trachea, another glottis bcing above for tlie iinal e»- 
capc of the air. These vertebrated animals lirst introduce 
us to the mechanism for articulate speech, the raven and paiTOt being 
able to pronounce words with distinctness. The articulation is ctlccted, 
as in man, by the motions of the tongue and other portions of the mouth. 
For the further consideration of this subject, it is necessary to under- 
Di»tl ct'on bp. *'*"■"*! *^^^ there is a distinction between song and spcccli. 
ihfcQMjnganii Song is produced by the glottis, speech by the mouth; or, 
perhaps, a more correct statement would be, that tho laiynx 



TftUuQg birds. 



Bplft'Cll. 



ii the organ of song, tlie mouth of that form of speech which wc call 
wlusi)cring, and for which nothing is required but a stream of nir issuing 
from tlic fauces, the tongue and other organs giving it articulation ; hot 
for audible sj^eecli, a noiao is created in the larj'nx, and modi6ed by ar- 
liculiitiun in the mouth. 

The double larynx of birds is replaced by a single larynx in man, 
wliich scn'os at tho same time for the entrance and exit of air, and like- 
wise for vocalization. Tliosc birds in which the lower larynx is absent 
are voiceless. A general idea of the construction of the organ of \-oicc 



ACnOK OF THE VOCAL C0BD8. 



353 



ninan may be gathered by supposing it to be composed of three por- 
tions, the trachea, the larynx, and (lie mouth. T!ic trachea ti<^ni.iion of 
a the tnbc by which air i^ brought from the lungs and de- ^*"= '«•".* "-'^ 
Itreied into the larynx, wliich is a ftU|>erpo3ed structure, arranged tipon 
llie cricoid cartilage, on which is articulated the thyroid cartilage by its 
lomr Horns, around which a certain degree of rotation can be accomplish- 
ed, so that the front of the tliyroid may be elevated or depressed with a 
kinti of bowing motion. Posteriorly, on the cricoid cartilage are placed 
ttio orytejioid c<-trliJ;igc3, wiiicli can be approached or separated from each 
i}(ber,and from their summits pass to the front of the thyroid cartilage 
the inferior larj-ngcnl ligaments or vocal cords. These constitute the 
csseniial organ of sound. The thyroid cartilage, by its motions, can de- 
Itnnine the strain put upon them, and the arytenoids can cither bring 
lliwa into p-iriilltOisin, or phure tlieni at an acute angle. The triiink or tis- 
i\m l«twecn tlicm is tlic rima glottidis : its figure and widtJi vary with 
lie recession or approximation of the vocal cords, which, as the air ]>a8S03 
W ifeem, are thrown into vibration in the same manner as the reed in mu- 
sical instruments. The epiglottis cartilage, which is above, guards the 
puuge, and may also bo supposed, by its descent, to deaden the sounds. 
The slowness or rapidity of the vibration is dependent on tlic stretch 
of tho vocal cords. The manner in which various degrees K«igQluion of 
"Jf tension can be given to tlie cords is readily understood by tb«»oe»l«>rt«. 
wnsidcring their attachmcitts. In front, as we have said, they arc fast- 
*!Qed 10 the tlijToid cartilage, posteriorly to the arytenoids. When tlie 
lit)TOid cartilngc executes a bowing motion forward, the vocal cords are 
pat upon the stretch, and similar variations of their tension and also of 
iluiir position can be given by the movements of the arytenoid cartilages 
Wiind. AVhcn the air is moving in and out without giving rise to any 
Wnnd, the chink of the glottis is angular, its iwint being forward, and 
''om that the cords diverge posteriorly. i*or the production of sound, 
^lie cords most be brought parallel, or even inclining toward each other. 
"ihcj incline away from each other, no sound will be produced. The 
pitch of the note will be determined by the strettth of the cords, and this, 
"1 itB turn, will be determined by the contraction of the vocal muscles. 
■*ne crico-tbyroid and stcruo-th'k'roid bow the front of the thyroid cartU- 
L*gc down, (lie thyro-arytenoiJ and thyro-hyoid carry it back ; the for- 
■^Cr therefore stretch the cords, and the latter relax ihem. The opening 
the glotlta is likewise determined by other muscles, the posterior cri- 
jytejioid dilating it, and the lateral crico-arytenoid and tho transverso 
noid clof^ing it. 

-f^ff. 181. p, 354, is the larynx, seen in profile: a, a,half of tho hyoid 
//, thyroid cartilage, cut; r, thyro-hyoid membrane; fi^ cricoid 
tilage ; tJ, trachea ; /', ccsophagus ; ^, epiglottis ; A, great hem of the 

Z 



854 



ACTION OF THE TOCAL ORGXXS. 



Fiy. 191. 



Fi-t. WS 







thyroid cartilflgc, united to, i', the grott bom of the oa by- 
oidea by, i, the lateral thyro-Iiyoid ligament ; /, thyn>-h»(i3 
mcmbmne, traversed by the sapcrior laryngeal ncm; m, 
posterior crico-arytcnoid miucic ; n, lateral crico-arrtenoiii : 
1, inferior laiyngeul ncr>'e; 2» posterior crico - arytcnoni 
twigs ; 3, lateral crico-arytenoid twigs ; 4, tliyno-arytenfiid 
twigs ; 6, arytenoid twig. 

7*7^7. 182 13 the posterior Wcw of the lar- 
Prouie "n^fjtuL ynx: a« base of the tongue; A, posterior bor- 
der of the thyroid cartilage ; c, c, thyroid body ; it, pos- 
terior crico-arytcnoid muscle; t, arytenoid muscle; 1, 1, 
superior larj^ngeal, traversing the superior thyro-hyoid 
membrane, and giving otf lingual and epiglottic branches, 
nnd others to the mucous membrane covering the poste- 
rior face of the larynx ; 2, twig for the arytenoid muscle ; 
3, anastomotic of (Jalicn ; 4, inferior laryngeal : 5, tra- 
cheal branches ; 6, twig for tlie posterior crico-arytenoid 
muscle ; 7» twig for the arrtenoid muscle ; 8, branch for the lateral crico* 
lurj'tenoid and posterior crico-arjtenoid muscles. 

The researches of MtiUcr furnish the best account we posse&s of ibf 
U&ller'acx. ftctiou of the vocal organs. He has shown that the Urrnx 
UuuUoDofUM ** essentially a reed instrument with a doable mcmfaraaoas 
toceI orffAM. tongue. Tliat the riran glottidis is the scat of the origin*/ 
the sound is proved by the fact that when an aperture exists in the tn- 
chea below the glottis the voice disappears, but if above the glottis then 
is no efFcct, Magendic i-ccords ihc case of a man who had a tistulous 
opening in his trachea, and who could not s])?^!!^ unless he closed it « 
wore a tight eravat 31orcover, the human or animal larynx can be mail 
to produce its characteristic sounds witit more or less distinctness, aflait 
has been removed from the body, by directing a current of ah: throng 
the trachea. Cases have occurred which have afforded the opjwrtnnilT 
of obsen'ing the condition of the glottis while emitting sounds. Tbs 
vocal cords arc brouglit into |iarallclism with one another, and sepamted 
by an inten'al of scarcely more than from the yj-^j to the -j-|^ of an inch; 
but when the air is moving in and out silently^ the tissure assumes a di* 
vergcnt or triangular form. 

Professor Miillcr gives the following account of the mode of produc- 
tion of the notes of the natural voice. " TIio vocal ligaments vibrate '^ 
their entire length, and with tliem the surrounding membranes aiid \^< 
thyro-arj'tenoid muscles. For the deepest notes, the vocal ligaments si' 
much relaxed by the approximation of the thyroid to the arytenoiJ (^ 
tilagcs. The lips of the glottis arc, in this state of the larynx, not oniT 
qmie devoid of tension ; they are, when at rest, even wrinkled and pl^' 



I 



» 



OP SINGING. 855 

cate«l, but they Income stretched hy the current of air, and thus acquire 
the degree of tension necessary for vibration. From the deepest note 
thas produced, the vocal sounds may be raised about an octave by al- 
lowing the vocal cords to have a shght degree of tension, which the elas- 
tic crico-thirToid ligament can give tliem by drawing the thyroid cartiJ-ige 
toward the cricoid. The medium state, iu wliich the corda are neitJier 
relaxed and wrinkled nor stretclied, is the condition for the middle notes 
of the natural register, tiiose whicii are most easily produced. The or- 
4inBry tones of the voice in speaking are intermediate between these and 
the deep bass notes. The higher notes are produced and the corTCS»pond- 
ing falsetto notes avoided by the lat