No. 462.

LONDON, SATURDAY, JULY 7. [1831-32.

LECTURES

ON

VETERINARY MEDICINE,DELIVERED IN THE

UNIVERSITY OF LONDON,BY

MR. YOUATT.

LECTURE XXXV.

THE MEMBRANES OF THE BRAIN-THE SIZE,

FORM, AND COMPOSITION OF THE BRAIN-THE FUNCTIONS OF THE CINERITIOUS

AND MEDULLARY PORTIONS, AND THE

INTELLECTUAL PRINCIPLE IN ANIMALS.

The Dura Mater in the Horse.-On en-deavouring to raise the roof of the skull inany of our patients, we find, adhering to’he inner surface of the bone, and separatedfrom it with difficulty, a dense and strongmembrane, the dura mater, at once the in-ternal periosteum of the bone, and thecovering of the brain. It adheres to thebone by innumerable prolongations of itssubstance, and by minute vessels, andthese are most plentiful along the sutures,and the ridges of the bones. If I macerateeither of the bones composing the craniumin diluted muriatic acid, the earthy matterwill be dissolved, and I shall have remain-ing the outer and the inner membrane-thepericranium and the internal periosteum-with a great deal of interposed cellulartissue, and numerous vessels of coramuni-cation.

Nature of the Membrane.—This adhesionto the bone gives to the dura mater a rough-ened surface exteriorly, while it presentsa polished, glistening face to the mem-branes below-thereby obviating injuriousfriction between them. The dura mater isunited to the membranes below by manylittle chords or prolongations of its sub-stance, and these particularly following thedirection of the sinuses. Each of theselittle chords or doublings of the membranecarries a small blood-vessel, and penetrate:

through the other membranes, and entersinto the substance of the brain, and is

firmly tied down wherever it enters, thusanswering the double purposes of carryingblood, and giving support to the brain orits membranes, and particularly in the direction of the great divisions or sinuses.This membrane consists of many laminae,and it is lacerated with much difficulty.

The manner in which it covers the Brain.-The dura mater completely envelops thebrain, but does not enter into any of itssinuosities or cavities; it accompanies theoptic nerve out of the cranium, and a pro-longation of it, but singularly modified, as1 shall have hereafter to describe, and nolonger adhering to the bone, passes throughthe foramen magnum, and encloses the

spinal marrow through its whole extent.The Longitudinal Sinus.-The dura mater

dips deep into the scissure between thelobes of the brain, and that in a very curi-ous manner. When it arrives at the cen-tral scissure on either side, it splits intotwo laminae, or collections of laminae. Oneof them passes over the scissure, and bindsthe lobes together; the other runs deeplyinto it on one side, lining, as it were,s the lobe on that side and then being1 suddenly inflected or turned at the bottom, of the scissure, it climbs up the other sideof the sulcus to reach the external trans-iverse portion, and thus forms a triangularr cavity-the longitudinal sinus-the reser-- voir of the superficial venous blood of thee brain, as- will be hereafter more fully ex-- plained.

The falx.—These laminae approximateto each other as they descend between thelobes forming the apex of this inverted tri-angle, and at length uniting, pierce yetmore deeply, under the denomination ofthe falx in the human being ; but from theflatness of the brain of the quadruped it ismuch less developed, and scarcely deservesthe name of a falx or scvthe. A similardivision and prolongation of this membraneis observable at the tenterium, dippingdown beneath the bony part in the form ofan irregular but narrow fringe. This du-plicature of the dura mater is particularlyextended in some animals that have not d

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bony tentorium. See this cranial cavity ofthe sheep, how perfectly it is partitioned !,into distinct chambers by these mem-branous curtains. In some quadrupeds,however, the falciform process of the cere-bellum is altogether wanting.The manner in which the praper falx and B

the tentorium meet each other at rightangles, and the support they give to eachother, and the manner in which both arerendered tense and effective, are worthy ofobservation. The lateral- sinuses are like-wise constructed of the laminæ of the ten-;torium ; and the sphenoidal and cavernoussinuses are formed from the splitting of the.dura mater.

The Dtcoa Mater in otlter DomesticatedAnimals.—I do not know of any consider-- able difference of structure in this mem-brane in our other patients, except that the,cavernous sinuses are mOte extensive in theox, and that they likewise contain a kind-of arterial reservoir derived from the ca-xotids.

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, The Arachnoid Membrane.—Beneath thecdur.a mater and separated from it by a smallportion of fluid, or at least of moisture onthe surface of the membranes, is the arach-noid t1tnic, so called frbm being as fine asa spider’s web. It likewise envelops thebrain. It is said to float loose between thedura mater and the pia mater, but it is tieddown by those chords and vessels from the,dura mater which penetrate through it in.order to reach the brain, and at these points- of union where we are occasionally enabled,to make a happy dissection, we find a por-tion of cellular substance of almost incon-ceivable delicacy surrounding the chord,and giving some strength to the attachmentof so fragile a membrane. The arachnoidtunic is most easily demonstrated at thebase of the brain superiorly to the originsof the optic nerves. Of its use I cannotconfidently speak; it may either be a se-

creting membrane to supply the fluid inter-- posed between the meninges of the brain,, or it may be destined in some raeasure to.cut off the communication between thebrain and the dura mater, and to prevent:its too much sympathising with any in-flammation or injury of the membranes of.the cranium.

It does not appear that either the duramater or the arachnoid membrane is en-dued with sensibility, and in none of ourpatients have we proof of that inflammationof the tunica arachnoidea of which medicalmen have spoken.- The Pia Mater.—Beneath these is the

- proper investing membrane of the brain-the pia mater—and which not only covers.its external surface, but penetrates into.every sulcus, lines every -ventricle, and

:clQthe5 every irregularity and portion and

part of the brain. So far as we can judge ofit by maceration, it is composed of delicate

but condensed cellular tissue; and, like thecellular tissue generally, it penetrates everv-where, being the vehicle by means of whichI the blood-vessels and the absorbents are

conveyed, by which strength is given toevery part, and by which they are at once

divided and united. The external surfaceof the pia mater is smooth and polished-the internal surface cannot be demonstrated- it may occasionally be torn off, but itcannot be dissected—it is, however, neces-sarily roughened by the multitude of ves-sels which it-conveys into the substance ofthe brain. Both the - pia mater and thearachnoid membrane are prolonged throughthe -whole extent of the spinal-cavity.

The B2cllc of the Brain.—We now arriveat the brain itself, and the first thing whichstrikes us is its comparatively diminutivesize in our domesticated animals. Look atthis brain of the human being, how broad,and rounded, and bulky, compared with theelongated, flat one of the horse and the ox.The human brain is double the size of thatof the horse, and, campared with the bulk ofthe animal, it is many times the size. Com.parative anatomists have given us a kind oftable of the proportionate,’ weight of thebrain. In the human being it has beencalculated at 3 part of the weight ofthe frame ; in the dog, according to hissize, it varies from to part; inthe horse it is in the swine inthe sheep (Carus strangely says);and in the ox -g 0 I i . Do we trace any con-nexion between this relative bulk of brainand the quantum of intelligence We seemto have been classing our patients prettynearly in proportion to their degree of in.telligence. But we are not yet preparedfor this.Form of the Brain.-The flatness of the

brain of quadrupeds, compared with therotundity of the human brain, is one of thefirst things, 1 have said, that will attractourattention; and the flatness, when we turnthe brain over, is far more remarkable be=

low than above. The convexity of the mid.I dle lobes is strangely diminished, whilethe posterior lobe is in a manner lot. These

circumstances, and particularly the last ofthem, account for the great difference in

the base of the cranium in the human beingand the quadruped,-the deep concamtiesof the one, and the comparative flatness andregularity of the other. Observe the pro-! longed oval shape of the brain in the horse,the ox, and sheep ; somewhat broader, in-

. deed, posteriorly than anteriorly, and thisassuming almost the form of a triangle inthe dog.1. . Irregularities of Suiface.-II-e recogonise an irregularity of surface, as on the humaa

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brain—certain prominences and depressions,but not so marked. The surface of thebrain in the quadruped is comparativelytame and inexpressive ; nay, some of ouroccasional patients have no convolutions onthe surface of the brain ; they are not foundip the hare, the rabbit, the rodentia ge-nerally, or the bird; and they are not so

bold or so deep in the ox as in the horse,nor so much so, compared with the differ-ence of bulk, in the horse as in the dog,—the swine holding an intermediate place be-tween the two. We must not dare to con-nect this with the proportion of animal foodby which each is nourished, although, inproportion as he is carnivorous, his brain isusually convoluted ; but I am afraid thatwe do not know enough of the functions 01any part of the brain of the quadruped, tcassociate these convolutions with anythingelse.Some comparative anatomists, whose de-scriptions are generally distinguished fortheir accuracy, have told us, that " in theopposite hemispheres of the cerebrum inanimals, the most exact correspondencemay be traced between the dispositions ofthe convolutions in both." This is erro-neous: compare together the hemispheresof these brains, and tell me whether youcan find in either of them this " most exactcorrespondence." I am bound to confess,that after having been in former years acraniologist, mv faith began to be shaken,and was at length overturned, by not alwaysfinding even ,the general resemblance"that exists in the human brain, and certainly" no correspondence between the convolu-

tions and the superficial structure of thebrain," and no possibility of discoveringit in the living animal, if such correspond-ence had existed.

The Divisions of the Brain.—The contentsof the cranial cavity are divided in prettynearly the same manner in all quadrupeds.There is the cerebrurn and the cerebellum, ’.the former divided into two lobes, and thelatter into three, or rather into two, unitedby a belt. There is considerable difference,however, in the relative size of the cere-brum and cerebellum. In the human beingthe cerebellum is about one-ninth of thebulk of the brain ; in the ox it bears thesame proportion ; in the dog it is one-

eighth ; in the horse one-seventh; and inthe sheep one-fifth : this, however, dependsupon the aga, for it is only in the adultanimal that the cerebellum is fully deve-loped. We have not yet inquired into thefunctions of these two portions of the brain,and when we do, I fear that we shall not beable satisfactorily to account for this differ-ence of bulk.

. The relative situation of the cerebrum andcerebellum present, as I stated in my last

B lecture’, only-an. apparent difference. Inthe quadruped the cerebellum is posteriorand even superior to the cerebrum; in thehuman being it is inferior; but this dependsupon the manner in which the head is con-nected with the atlas. In both the cere-bellum is the portion nearest to the fora-men magnum, and under which the cruracerebri must pass to arrive at the medullaoblongata and spinal chord.

The Difference in the Composition of theBrain.—lf I cut into the brain, I find itcomposed of two substances very unlike in

their appearance. The one from its situa-tion on the outside of the brain is called thecortical, and from its reddish ashen colour,:. the cineritious substance ; the other, from

f I its pulpy nature, and found deeper in the

) brain, is termed the tnedullary substance.Long z’ hardening in alcohol has proved themboth to be of a fibrous structure, and has

- confirmed the old opinion that they arer essentially distinct from each other, as well as of very different composition. Placed in-i apposition with each other, and seemingly* mingling, they never change by degrees

into one another, or run, as it were, into- the same mass.The fibres of the cineritious portion run

in various ways : on the surface of the brain

they are vertical,-deep within the brain,they take every possible direction. While

they are unconnected with the medullarysubstance, they are in a manner isolatedamong each other. The medullary fibresare connected throughout the brain. Theyhave all a direct or indirect tendency to-wards the centre and base of the brain 7and from their common centre, or condeiisa.tion of substance and influence and power,the nerves derive their origin. The nervesseem to be prolongations of the medullarysubstance. The cineritious portion is scat,.tered every-where, chiefly distributed to-wards the outside of the brain, but foundalso deep in its centre ; and striæ, or por-tions of it, at the root of every nerve. Themedulla oblongata and the spinal chord areevident prolongations of it.

Tlte Proportions of Medullary and Cineri-tious Portions in different Animals.—Thefacts that I have just stated led to the mostinteresting inquiry in which the physiolo.gist can be engaged, viz. a comparison be-tween the brains of various animals—the

proportions of these two substances in each,and the character and destinv of the diner-

ent animals ; and the conclusion drawn from.such an inquiry will be arrived at withoutdifficulty, and kvill be perfectly satisfactory.Compare together these brains-that of thehuman being, the horse and the ox. Ob-serve, in the first piace, the development,greater beyond comparison, of the nerves ofsense in the brains o.f the inferior animals;

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compare the olfactory nerve in the humanbeing and the quadruped, (I must maintainthat it is a perfect nerve, although our bestcomparative anatomists have degraded itinto a mere mammillary process,) that he-longing to the human brain is not one-fourth the size of the same nerve in thehorse, nor a sixth part so large as that inthe ox. Compare the optic nerve in thebiped and the quadruped, the size of thetractus and the bulk of the nerve itself-the auditory nerve affords as satisfactory apoint of comparison. Examine that whichI have described as the common centre ofthe medullary substance or influence, thatwhich gives origin to every cerebral nerveof sensation and of motion : first. the cruracerebri, mere chords in the human being,compared with the broad and bulky pillars Iof the quadruped. Observe the medullaoblongata, the centre or the condensation ofthe medullary matter of the cerebellum aswell as the cerebrum-the origin or com-mencement of the spinal chord-connectedwith loco-motion, with strength and com-mon sensibility-connected too, as we shallhereafter see, with the powers of organic aswell as animal life. How striking is thedifference !—the breadth of the medulla ob-longata in the human being’ is but one- Iseventh part of that of the brain ; in thehorse and ox it is nearly a third ; in the dogit is more than a half ; in the hog it is morethan two-thirds. Notwithstanding this

disproportionate bulk of medullary matter,the brain of the horse, the ox, the swine, andthe dog, is comparatively less, much less thanthat of the human being. The brain of the

dog is scarcely a fourth part of the propor-tionate weight of the human being; the brainof the ox is not a twentieth part. Then howis this difference made up? Why in thecortical or cineritious parts. That pre-ponderates as much in the human brain asthe medullary substance does in the brainof the Quadruned.

The Functions of the Medullary and Cine-7’ttMMS Pa1’ts in the Human Being and theQuadruped.—Now then, Gentlemen, a littlelight begins to break in upon us. In thequadruped the medullary portion prepon.derates; in the human being, the cineritious.In the former, the senses are acute and themuscular power is great ; in the other thereis or ought to be a stronger mental principle.The hunter will recognise the cry of thehounds, and his ears will be erect, and hewill be all spirit and impatience, long beforehis rider is conscious of the least sound.We soon find in the exercise of our pro-fession, that when all is dark and blackaround us, we can trust to the keener visionof our horse, who, if we resign ourselves tohis guidance, will carry us safely through theintricacies and dangers of the road, and

we must have carelessly observed him, if wehave not been taught that the sense ofsmell supplies in him the place of the senseof touch and lessons of experience. To thisit must be added, that in power or quicknessof muscular action, according to the kind ofservice that we require, he is all that wecould wish. ln the human being, the sensesare comparatively dull and obtuse-neitherin hearing, sight, or smell, can we vie withthe meanest brute, but we have the powerof thought to arrange and to compare theintimations which our senses afford us, andto extract from them all that is necessaryfor our existence and comfort, and to combine with the impressions that we receivefrom them many an association whichrenders them productive of intense delight;and, best and noblest of all, to make them

the foundation of intellectual improvement: and moral worth.

Comparison between the Cineritious and

Medullary Substance in different Quadrupeds.- Observe these brains-that of the horseand that of the ox. The brain of the horseis considerably the larger of the two-itsrelative weight is nearly double. How isthis difference made up ? In some parts ofthe base of the brain there is more medul.

lary substance in the ox than in the horse-! the medulla oblongata and the spinal chordare larger—the additional bulk of brain inthe horse is composed of cineritious matter.Observe again these brains-that of the dogand of the sheep. The dog was not halfthe size of the sheep, and yet his brain islarger, although, if we examine the base ofboth, there is proportionally more medul.lary matter in the sheep than in the dog.Here again the additional bulk of brain is

composed of cineritious substance. Howdifferent is the character of these animals !-the sluggish stupid ox, and the intelligent

, horse-the silly sheep, and the intellectual,companionable dog. I must not use de-cided language on such a subject, but theconnexion between the cineritious part ofthe brain and the intellectual principle,and that between the medullary portionand the mere animal principle, does seemat least highly probable. The latter is themedium through which the impression isconveyed, or the motion is effected—theformer is the substance to which that im-

pression is referred, where it is received,registered, and compared, and by whichthe operation of the motor nerves is influ-enced and governed ; the one is providingmaterials to work upon-often rude anduseless beyond the present moment-thelatter is surveying and arranging them, andbuilding up the fabric of intellectual andmoral worth.

Brutes.— The Preponderance of Anímal Power inBrutes.—The substances of which the brain

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is composed are the same in all our patientsand in every vertebrated animal. They differonly in the mode of arrangement, and intheir relative quantities. It is what weshould expect, after experience has taughtus that the difference between the human

being and the brute, in intellectual and inmoral worth, consists in degree and not inkind. The animal portion of the brain pre-ponderates in each-and in each withbeautiful adaptation to the situation inwhich he is placed, and his connexionwith man. Look once more at the olfactorynerve, bearing in development an invariableproportion to the necessity for acute scent,not only for the purposes of the animal in-dividually, but of man. Observe this nervein the horse, how large compared withthat of the human being-larger in the ox,who is not so much domesticated, andoftener sent into the field to shift for him-

self-larger still, in the swine, who is tosearch for a portion of his food buriedunder the soil, and immersed deeply inrefuse and filth, and largest of all in the

dog, the acuteness of whose scent is somuch connected with our pleasures. Aswe advance in our subject, the organicnerves will pass in review before us, andthere we shall observe the same compara-tive difference, both in those of the spine,and the deeper-seated ganglia-the motor,and the secretory or chemical organicnerves-the worth of the horse dependsupon his wind, and that of the ox on hisdisposition to fatten.

The Dimiarution, yet existence, of Iratellec-tual Power in the Brute.—Then this corticalpart-once more observe it, compare it.

Forgive a little repetition here. How differ-ent its relative quantity-whether comparedwith the human brain, or those of variousanimals ! Once more observe it in the dog,the horse, the sheep, the ox-compara-tively small in each-diminishing in eachaccording to the evident proportion of intel-ligence. Smallwe say in each, for in theirwild state the brutes have no concern, andno idea beyond their food and reproduction-in their domesticated state they are

destined to be the servants of man. Theacuteness of their senses-the preponder-ance of the animal power, qualify them forthis service, but were proportionate intel-lectual capacity added to this-were theymade conscious of their strength, theywould burst their bonds, and man would inhis turn be the victim.and the slave. Stillhowever the cortical part is found in each,prevailina in each as it would seem to beneeded for our purpose that intelligenceshould be added to animal power. In eachthe organisation, the connexions, appealto be the same, and the distinction in theintellectual—aye, and even the moral quali-

ties in the biped and the quadruped, is indegree and not in kind-nay, it may so

happen, that the one being advanced andimproved by circumstances, and the otherretarded or contaminated, there may bemore difference between the cultivated andgood man, and the savage and depravedone, than between the biped and the brute.

Conclusion.-If we had time I mighttrace in our patients the palpable existenceof every mental faculty-attention, me-

mory, association, imagination, judgment;and I might trace too, shall I say, theBerm—no, the full development of many avirtue-parental, filial, social affection--..courage, fidelity, gratitude, disinterested-ness, and a consciousness of right andwrong. This would be a pleasing relief toour severer inquiries into anatomy and dis-ease-it would reconcile us to our pro-fession-it would teach us to admire and tolove those whose medical guardians andfriends we had undertaken to be-it wouldgive that impelling principle, that aim andobject, which would ensure our professionalsuccess. To this subject let your atten-tion be often directed, every day will affordyou pleasing illustration of it, and the re-sult will be that your professional fame willbe established on the only sure basis-science and humanity.

LONDON HOSPITAL.

CLINICAL LECTURE

BY

DR. BILLING,

Delivered Jan. 21, 1832.

TUBERCULAR CONSUMPTION.

IN the lecture to-day, Gentlemen, I shalltake the opportunity, in tracing the progressof cases of that scourge of our country,tubercular consumption of the lungs, to

point out to you those diagnostic symptoms,which you will be constantly and anxiouslyrequired to decide upon in the future exer-cise of your profession; and at the same

! time that I show you the inflexible charac-ter of the disease, and how slight the chanceis of recovery from it, let me impress uponyou the possibility of temporary, and evenof permanent cure, and the rational mode ofattempting it. In order to illustrate the

symptoms of the stages of this formidabledisease, I have laid on the table a series ofspecimens of the tubercles of the lungs atdifferent periods of their progress, and ofthe destruction of the lung subsequently,besides that which has been preserved from