No. 444.

LONDON, SATURDAY, MARCH 3. [1831-32.

LECTURES

ON

VETERINARY MEDICINE,DELIVERED IN THE

UNIVERSITY OF LONDON,BY

MR. YOUATT.

LECTURE XX.

TRACHEOTOMY.-THE THYMUS GLAND.-

THE BRONCHIAL TUBES.

THE respiratory canal is occasionally, andto an annoying and dangerous degree, ob-structed. Polypi occupy the nostrils. I irelated a case of one in a former lecture,which completely filled one nostril, and z,

thrust the septum narium so far out of itsnatural situation, as to cause serious im- ’,pediment to the breathing. Bony tumourshave been formed in the nostrils, and ob-structed the current of air. Tumours havedistended the guttural pouches, and pressedinto the pharynx. The tongue has becomeenlarged, or the membrane of the pharynxhas been thickened by inflammation, andclosed the passage to the larynx; or thetumour of strangles has pressed upon thepart, and for a while obliterated the pas-sage. Foreign bodies have lodged in thepharynx, or have even insinuated them-selves into the trachea. The larynx hasbeen distorted by tight reming; bands ofcoagulatfd lymph have been thrown acrossthe tracheal tube ; the membrane of the

windpipe or of the larynx has been thick-ened, or ulcers have formed in the larynxor the trachea, so sensitive and so painful,that the act of breathing was laborious andtorturing. In any of these cases we have

anxiously inquired whether we might notestablish an artificial opening for the pas-sage of the air, when the natural one couldno longer be used ; and we have found it tobe a very simple and safe operation to cutinto or excise a portion of the trachea,

either upon or below the point of obstruc-tion, as circumstances may indicate.

Description of the Operation (of Trache-otomy.—The operation being determinedon, and the precise spot at which it is to beperformed being selected, the horse is se-cured by the side-line, if he is standing.From the violent struggles with which hewould resist the act of throwing, he wouldprobably be suffocated. The twitch is then

firmly placed on the muzzle, and the headelevated—the operator, if necessary, stand-ing on a stool or pail, that he may moreperfectly command the part. A scalpel,scissors, bistoury, curved needles armed,and a moist sponge, should be held by anassistant.The hair is first to be closelv cut from the

part ; usually between the nfth and sixthring. The integument is then to be tight-ened across the trachea with the thumb and

fingers of the left-hand, and an incision

cautiously made through the skin, threeinches in length, the operator being pre-pared to raise the knife at the least motionof the patient. The subcutaneous tissuewill thus be brought into view.The operator must have previously de-

termined what kind of incision he will makeinto the windpipe. It has been usual tocut out a small slip in the centre, half aninch wide, and including one or two wholerings and the connecting ligament aboveand below. To this, however, there isserious objection. When some of the ringsare thus perfectly divided, the arch willbe weakened; its form will no longerbe preserved; it will assume a sharper,roof-like shape, and the calibre of thetrachea will be afterwards considerablylessened in that part, and the consequenceof this will probably be roaring to a greateror less extent. An immediate pressingdanger may be removed, but a permanentinconvenience will be established. Hereare three windpipes, on each of which youwill perceive the operation of tracheotomyhas been performed. The cartilage hasunited, but it has united by approximationrather than by reproduction: the front ofthe trachea is sharp instead of round; the

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sides are fallen in, and each animal was pro-bably a roarer.

Caution as to the Excision of the Rings.—I should advise you to adopt another me-thod. Excise a portion of two of the rings,about half of their width, with the interven-ing ligament. The remaining portion willbe sufficiently strong to retain the perfectarch form of the trachea ; and if you thushave the aperture a little shorter, you mustmake it somewhat wider.

But when you have done with, and wantto close, this artificial opening, will’the car-tilage (the edges of which cannot approxi-mate) be reproduced? Yes, perfectly.Here is a beautiful specimen of it. The

rings are a little thicker and wider, but theyare perfect, and the arch of the windpipeis altogether preserved. I

Well, then, Gentlemen, if you are to

excise a portion wider than it is long, youmust not only dissect and turn back thecellular tissue, and the sterno-thyroideusmmscle, to the required extent, but youmust remove a portion of both, until youhave sufficiently exposed the windpipe ;your aperture will be about half an inch

square, or perhaps a little wider than it islong. There are no blood-vessels of anyconsequence to interfere with this dissec-tion, and the haemorrhage will be slight.

Manner of Excising the Rings.—The sur-geon will now exchange the scalpel for asharp-pointed bistoury, and plunging itinto the ligament at the point which is tobound the aperture laterally, he will carryit upward until he has cut half way throughthe ring. He will then turn his hand andcarry the knife transversely along the middleof the ring, until he has arrived at the boun-dary of the intended aperture on the otherside ; another turn will take the knife

through the lower half of this ring, theligament, and the upper half of the ringbelow : he will then pursue the same linealong the centre of that ring, and afterwards,taking hold of the part now almost detached,he will complete the excision by one moreturn upward. The bistoury should be keen,and the hand should glide as swiftly asthe preservation of the form of the aper-ture and half the substance of the ringswill permit. Some make a simple incisioninto the trachea, and then introduce a smalltube. I shall speak of the tube presently;but this incision mustibe much longer thanis necessary in the operation I have de-scribed ; two of the rings at least must becut through, and then there will be a longer,roof-like projection, and greater contractionof the trachea.

It is wonderful to observe what. instan-taneous and perfect relief this affords ; thehorse that was struggling for breath; and

seemed every moment ready to expire, isin a moment perfectly himself.No Tube to be inserted.-What is now to

be done with the incision ? That dependson the purpose to be effected by the opera-tion. If the orifice is only to be kept openwhile some foreign body is extracted, orulcer healed, or tumour removed, or in-flammation subdued, nothing more is ne-

cessary to be done, than to keep the lips ofthe integument a little apart, and that maybe effected by passing some strong threadthrough each, and somewhat everticg themand tying the threads to the mane. A tubeis not required ; it is injurious rather thanserviceable ; it must irritate the lining mem-brane of the trachea, and, occasionally, atleast, annoy the animal and produce con-siderable inflammation.

T’ubes in permanent Obstruction.-If, how-ever, there is any permanent obstruction,as a large tumour in the cavity of thenostrils, or distortion of the larynx or tra-chea, then a tube will be convenient. Itshould be two or three inches long, curvedat the top, and the external orifice turn-

ing downward, with a little ring on eachside, by which, through the means of £tapes, it may be retained in its situation,will answer every purpose. It should betaken out and cleaned daily, and the woundattempted to be healed, leaving only a suffi-cient aperture for the canula. The Frenchhave an oval plate, of which here is an

engraving, three or four inches long by twowide, to the inside of the lower part ofwhich is affixed a canula or tube; imme-diately above the tube is a smaller moveableplate in the centre of the other. Whenthis plate is up, or open, the horse easilybreathes through the aperture, but when thatis closed it is immediately put to the test,whether the natural passage for the air has

again become pervious, and the plate mayeasily be pushed up if the respiration shouldbe laborious, or suffocation should threaten.The shield-like plate is retained in itssituation by tapes. This is an unneces-

sarily-complicated apparatus. The simplecanula will answer every purpose.

Curious Case of Tracheotomy.—There is asingular but well-authenticated account ofan operation performed by Barthelmy, oneof the professors at the veterinary school atAlfort. There was great distortion of someof the rings of the trachea, and the animalbreathed with difficulty, and became a

roarer almost to suffocation; she was quiteuseless. Tracheotomy was effected on thedistorted rings, and a short canula intro-

, duced. The mare was so much relievedthat she was trotted and galloped imme-

diately afterwards, without the slightest, distress. Six months afterwards she againbeg.4a to roar; it seemed that the rings

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were now distorted below the former place.Barthelmy introduced another canula, seveninches long, and which reached below thenew distortion. She was once more re-lieved ; she speedily improved in condition,and regularly drew a cabriolet at the rateof seven or eight miles in the hour, andthis she continued to do for three years,when the canula became accidentally dis-placed in the night, and she was found deadin the morning.

Tracheotomy on other Animals—Tracheo-tomy has been practised with success incattle in cases of laryngitis, to which theyare more exposed than the horse. No casehas come under my personal inspection,but two or three are recorded in the French

journals, in which immediate relief wasafforded, and an eventual cure produced.Once I operated on a dog with enormous

tumour in the throat, which almost strangledthe dog. The case was successful.

I assisted Professor Mayo in performingthe operation of tracheotomy on a rabiddog, whose respiration was peculiarly labo-rious and stertorous; it produced no effect.The difficulty of breathing, almost threaten-ing suffocation, seemed not to be dependenton any spasm of the glottis. The peculiar,harsh, grating, sound ceased; but the lungsheaved as violently as before, and the ani.mal died in less than twelve hours after the

operation.Ilealing the Wound.—We well suppose

that the desired effect has been produced. ITime has been’allowed for removal of theobstruction, or the subsidence of inflamma-tion, and we wish again to close the artificialaperture. Nothing is so easy. We lightly I,scarify the cellular and muscular substance I

beneath, and the inside of the integument ;we bring the lips ot the wound neatly to-gether, having previously scarified or paredthem ; we confine them bv a suture ; weplace a little dry tow over the wound, andconfine it by a loose bandage : and not onlywill the external wound be healed in a fewdays, but in process of time, as you see inthis specimen, the cartilage wili be repro-duced, and the trachea be as perfect as ever.I need not caution you I think, that in ex-tensive inflammation of the aerial passages,or in inflammation of the lining membraneof the trachea itself, although attended withdifficulty of respiration, and that almost

threatening suffocation, this operation wouldbe more likely to increase the inflammationthan to produce a beneficial effect.

THE THYMUS GLAND.

Well, Gentlemen, we once more tracethe entrance of the trachea into the thorax,and it has scarcely penetrated between thefirst ribs ere, in a young subject, it comesin contact with an irregular glandular body

situated in the doubling of the anteriormediastinum. This is of a pale pink colour,and of a lobulated structure like that of the

salivary and pancreatic glands. It is the

thymus gland, or in vulgar language, thesweetbread.

Its progressive Development.-In the earlyperiod of utero-gestation, it is of very in-considerable bulk, and confined mostly tothe chest, but during the latter monthsit strangely develops itself. The superiorcornua protrude out of the thorax; climb upthe neck between the carotids and the tra-chea; are evidently connected with the thy-roid glands, and become parts and portionsof the parotids. The parotid and the thymusglands are, in the latter months of foetal life,essentially the same; composed of a multi-tude of granules arranged into lobules, whichare of greater or less size, and envelopedbv slight and easily lacerable membranes.When they are cut into, a milky fluid isobserved in both, the composition of whichhas not I believe yet been examined. Theycannot be dissected from each other; theone is a prolongation of the other, and theonly difference in them is, that the parotidduct can be traced into the mouth, butno duct has ever, that I am aware, beentraced in the thymus gland.j Identified with the Parotid.—Here is a

beautiful dissection of it. Prolongations ofthe thymus, and those of considerable sub-stance, climb the whole way up the neck onboth sides, loosely connected with the thy-roid glands by cellular substance, and atlength, as you will see, identifying them-selves with and inseparable from the paro-tid. It is abundantly supplied, as you willperceive, by blood-vessels, and at whateverpart we cut into it, a milky liquor exudes.

Singular Disappeurauce of the Gland.-Soon after birth a singular change takes

place. It separates from the parotid. The

separation increases--or, rather, the glandgradually disappears, beginning from abovedownwards ; and in the course of a fewmonths not a vestige of it remains alongthe whole of the neck. It more slowly di-minishes within the thorax, and at lengthdisappears there too, and its situation isoccupied by the thoracic duct.

huractiora of the Thymus Gland.-Physio-logists have not agreed on the function ofthe thymus gland, or, rather, very few ofthem have ventured on any explanation ofits use. It is evidently connected with thestate of fostal existence-more particularlywith the latter stage of it; and when theanimal is born its function seems to cease, forit separates from the parotid, it disappearsdown the neck, and at length vanishes al-

together. May not the hitherto unobservedconnexion between the thymus and parotidgland in the fostua throw some light on

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this subject They seem to form the ex- tremities of the same gland, and secrete

the same fluid ; and the parotid dischargesits contents into the mouth. True the pa-rotid after birth is a salivary gland, but isit of necessity so when connected witti thethymus ; or does it not then evidently se-crete a different fluid-a milky one, and pre-cisely of the same apparent character withthe fluid which is often, or generally, foundin the stomach of the foetus? Magendiespeaks of the opaque and greyish fluidfound in the stomach, and which seemed tohave undergone a digestive process; and allanimals have a portion of feculent matter,if I may so term it, in the great intestines,the probable or evident process of a kind ofdigestion.

Conneeted uzih Nutrition.—The thymusgland then is possibly connected with thenutritive system. It pours a bland and

milky fluid through the parotid duct intothe mouth, and so into the stomach, iu orderto habituate the stomach by degrees to thedigestive process, to prepare it for that func-tion on which the nutrition of the animalis to depend ; and also to prepare the intes-tines for the discharge of their duty-the’separation of the nutritious matter, and thepropulsion down the canal of that whichis fecal. I dare not affirm anything posi-tively on a subject on which so many ablephysiologists have been silent; but I thinkthat from this connexion between the two

glands, a glimmering of light breaks upon us;and that we have, in the later period offcctallife, when alone the thymus gland is fully

developed, the beginning of the first essayat the preparation for those important func-tions in which the stomach and bowels are

THE BRONCHIAL TUBES.

We had in our last lecture followed thetrachea through the duplicatures of themediastinum to the base of the heart, andthere, beneath the curvature of the poste-rior aorta, it separated into two tubes cor-responding with the two divisions of thelungs ; these are the bronchial tubes. The

right is somewhat larger than the left,because, as we, shall presently see, the rightlung is larger than the left. These maintrunks plunge deep into the body andsubstance of the lungs. They presentlysubdivide, and the subdivision is continuedin every direction, until branches from thetrachea penetrate every assignable portionand part of the lungs. These are still air-

passages, they are carrying on this fluid toits destination for the accomplishment of avital purpose.

Theii- Construction.—It is still necessarythat they should be pervious, or that theircalibre should not be long obliterated. They

are now exposed to a new pressure ; a pres. sure alternately applied and removed,-towhich they are compelled to yield, butagainst which they must, to a certain extent,struggle, and in consequence of that strug-gle regain their former calibre the momentthe pressure is removed. The lungs inwhich they are embedded alternately con-tract and expand, and these tubes must con.tract and expand again with the lungs. Theperfect cartilaginous ring of the tracheawould not be sufficiently yielding, or foldup sufficiently close. Yet there must beresistance and elasticity. We have it, andwe preserve the cartilage while we have it.The ring remains, but it is divided into fiveor six see-ments connected together. The

ligamentous muscular band which connectedeach ring with its neighbours is no longerfound ; there is, however, a thin, yetstrong and elastic substance. The lungsbeing’ compressed, the rings yield, and thesegments overlap each other and they foldup and occupy little space ; but elasti-

city, although latent, is still at work, andas the pressure is removed they start againand resume their previous form and calibre.It is a beautiful contrivance, equalied onlybv the structure of the trachea ; and bothexquisitely adapted to the situation inwhich they are placed, and the functionsthey have to discharge.

Number of Segments.—In the larger divi-sions of the bronchiæ we can trace in eachring five or six of these segments. As thetubes decrease in calibre the cartilage isthinner and the segments are fewer. Hereare plainly five ; here we can trace onlythree. A little farther on, and we can per-ceive from the yielding nature of the thmcartilaginous ring, that it is divided into seg-ments, but we cannot clearly ascertain thenumber, certainly not more than three : a

little farther and the cartiiag’e can no longerbe traced, but the impression remains onthe tube ; it is there, but so thin and flexibleas not to be distinguished from the liningmembrane.

Termination of’the Bronchiæ—And so wetrace the bronchiæ until they almost eludeour sight : yet we can pretty satisfactorilyfollow any individual ramification until itarrives at one of the lobuli into which thesubstance of the lung is divided. We aresure that it enters there, otherwise thefunction of respiration could not be perform-ed, but we have no ocular demonstration ofthe fact, nor of the real termination of theseair-passages. There are some very prettytheories about this, and to a certain extentthey probably are true, but we have no

demonstration; and therefore, Gentlemen,at the fragile membrane which covers thelobuli, we will, if you please, leave thebronchial tubes.

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I should state that so far as we can fairlvtrace these tubes they are lined by a con-tinuation of the membrane of the trachea.This membrane is subject to inflammation,which I shall hereafter describe.

Blood-vessels.—The bronchial artery risesfrom the posterior aorta and from the poste-rior face of the curvature of that vessel, bythe side of the ccsophagean artery, and some-times from that artery itself. It advancesin a serpentine direction towards the leftbronchia, and there it divides and sends anearly equal brane.1-i to the right and to thelelt. These arteries penetrate into the sub-stance of the lung’s, and ramify on the bron-dual tubes through the whole of their course.the bronchial v eiii follows the course of theartery through the lungs, and pours itselfinto the vena azygos at its curvature, andclose to the ossopbagfan vein. Sometimesthese veins unite before falling into the

azygos.Before I proceed to the structure of the

lungs generally, and particularly of theselobules at which I have arrived, I mustlook around me and consider the cavity intowhich I have entered. The structure andcontents of the thorax will form the subjectof our next lecture.

ON THE USE OF

ALKALINE SALTS

IN THE CURE OF

TYPHUS FEVER, CHOLERAASPHYXIA,

AND OTHER IMPORTANT DISEASES ;

Tending to prove the Identity of the Causes ofthose Diseases: illustrated by Cases.

By PAUL SLADE KNIGHT, M.D.

(Concluded from page 761.)

WITH respect to the doctrines that assigninflammation of the brain as the cause oftyphus fever, I have brieflv to observe, thatthe evidence of such affection is very farfrom being always present. A late authortells us, that of 54 patients who had died ofthis fever, and whose heads were examined,only 37 showed marks of cerebral inflamma-tion having’ existed. So of the doctrinesthat assign the cause of fever to inflamma-

tory aiffction of the intestinal mucous mem-brane. Of 60 that were examined, only 24had been affected with inflammation of theintestinal mucous coat, of whom 15 hadulceration of the small intestines, and 16ulceration of the ileum and small intestines.Thus we learn that both the inflammation ofthe brain and the ulceration of the intes-tines are only accidental ; they sometimes

accede to the other symptoms and sometimesthey do not; morbid anatomy, therefore,proves, that neither inflammation of thebrain, nor of the intestinal mucous coat, isessential to fever. I question not that thebrain is very frequently found to have suf-fered from inflammatory action in typhus.Indeed, I know it to be a fact; and aslittle also do I question the existence ofinflammation and ulceration of the intestinal

mucous membrane, for this also I know tohappen ; but I do deny that either the oneor the other can be regarded otherwisethan as accidental; and were it a cause ofthe disease, it is incumbent on the advo-cates of this doctrine to show why evidenceof its existence is not always present, alwaysto be found ; since, according to their doc-trines, the affection has been so severe asto cause death. If death be the result ofphrenitis, pneumonia, gastritis, &c. &c., abun-dant evidence of the disease is alwaysfound ; were it, therefore, essential thatinflammation of the brain, or inflammationof the intestinal mucous membrane, shouldbe the cause of fever, the evidence of theirhaving’ existed would as surely be found asthe evidence of the inflammatory actionson any other parts producing death ; but if,on the contrary, their appearances are notfound in one-half of those who die, and thistoo, be it remembered, after cause andeffect have done their utmost, that is, havedestroyed the patient, am I not entitled toassume that gastric irritation, which is al-ways present in fever, is the cause of thephenomena of fever (the accessions or re-missions being independent, and referable tothe laws that govern our systems in healthas well as disease) ; and am I not equallyborne out by the facts in assuming, that thiscause is the effect of an acid of a peculiarlymorbific kind, which is lodged in the sto-

mach and intestinal canal? A cause-thereis, I trust mv readers will find, abundantground for belief-in the frequent dreadfuleffects produced by acid alone, fully equalto all the effects found either in the intes-tines or the brain, when the fever-patienthas been suffered to remain for weeks a

martyr to its all-but-unmitigated acrimony.I repeat, that these ulcerations of the in-testines, and the inflammation of the brain,are what may be expected from such cause,when its acrimony has only been mitigatedby gum-water, or milk and water, or an

occasional dose of some saline medicines,although an attempt be made to counteractthe inflammatory actions by general andlocal bleeding, poultices to the abdomen,&c. Because, reasoning from the cases Ihave to relate, I feel I am entitled to insistthat the same cause, namely, a peculiarmorbific acid being present in the stomachand intestines, does produce excess of vas-