The economy of the animal kingdom, considered anatomically, physically, and philosophically

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a perpetuat conspiring of the said viscera, WOuid nover bo the

VI.38. NoW since in creatures of this very Simple character We Observe SO close a conjunctiori belWeen the pulmonary pipes audtho bratus, that there is reason sor belleving that the One is necessarily agitaten and as it Wero ventilated by and with thoother; heiace We may lairly suspect that there is also a similarcommerce belWeen the uir that We dram into the cavities of thonares and convey to the pulmonary Vesicles, and the brain. Fornature is the fame in the least sphere as in the greater and thegreatest, although With a disseretice of connection and degrees. NoW then let us see What influx there is of the air draWnthrough the nostriis into the brain Wheu it animates. Butbelare We can touch this subject closely, We must meli examine the mammillary processes, and the olfactory nerves proceed ingsrom them, as also the cavities of the ethmoid bone, und compare these paris With the phenomena presented by the insecttribe, as discovered by the microscope, and mentioned in thepreceding Sectiori V., Π. 34-36).39. In man the mammilla processes are very thin and smali, but in other animais, and more especialty in those Whichliave an acute sense of smeli, they are Iike two botiles, ve large and round, broad at their commencement, and deeroasing by degrees, and they occupy a very considerable part of the base

tain a cavi ty fuit of limpid fluid, the insation of Whicli cavi tyby means of the bloWpipe Wili cause the Whole mass of thebrain to rise and sWeli vp; according to the experience OfWillis. rebri Analome, cap. i.) They lie upOn the dura mater, ali the Way from the clinoid processes to the ethmoid bone; they are pretiy sost; and When they reach the cribriform plate of the crista galli, they transmit a vast number of filaments through iis foramina. As these descend, they are invested With and accompanted by an eques number of titile prolongations of the meninges of the brain, and proceed untii they reacti the

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pulpy flesti und folliclos and granulatod substance of the pituitary membrane, in Whicli they torminate. Some authors derive the origin of the fibres Oxtensively Dom the posterior and anterior Iobes, and from tho middie portion Os the centrum ovale; Some, more limitedly, Only froin the anterior part of the medulla oblongata, and from the corpora Striata, from Whicli, running Obliquety in concealment, they ut last come out betWeen theanferior and posterior lobes.' MeanWhile the pituitary membratio in Whicli they are inserten, expands far and Wide, malitia ga variety os circumflexions, sor it insinuntes itsulf in to the cavities of the si x sinuses, and tuto the Dur celis of the spongyand turbinat ed hones. 40. From this stight description Os the mammillary pro-CeSSOS, olfaetory nerVes, and eavities of the ethmoid bono, Wemay See hoW it happens, that no uir can be drawn through thonostriis into the larynx and trachen, Or into the lungs, Without in iis passage sirst coming in contact With the papillae, gland8, Sensitive membranes and fibriis, Whicli are derived Dom thobratia into the expandod pituitary membrano that invests the Ove cavities. Thus Whether the air bo cold or Warm, or sillud vitii fragrant or fetid effluvia, this ouisprending Sensorial organwill necessarily bo irritated by the contact; and is the organ, then also iis meningeat fibro and prolongation; and is these, then the medullary substance of the brain is excited, With Whichthe above processes Dom the corpora Striata communicate On ull

lary and interior substance of the brain, and at the fame timeboth iis membranes, or the exterior, bo excited, it is impossibie but that tho cortical substance mediate betWeen both, and continuous With both, must be re dured conscious and participant of the contaci and irritation; in other Words, it is impossibiel, ut that tho sense shali instantaneousty diffuso itself throughout the Whole brain, a1id, as We may fairly conjecture, excite it to

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brain With pleas ure tu a fragrant garden, and hoW struightly and with What constricted lungs We brenthe in an atmosphere Offotist smelis. 4I. But Whethor tho uir itself, or rather iis Warm or coid temperature, and Whether the effluvia that it contains in large quantities in the loWest atmospherie strata, as Osten as they are inspired, excite the brain to aut, is a question Whicli cannot beillustraten more olearly than by contemplating the greatest de-gree of excitation perceptibi e to Our senses. Having done this, We may proceed to draW insereticus With respect to the lesserdegrees, Whicli scarcoly come Within the sensibie sphere at all. S1100ging' is the highest degrese of animation Or respiration, and ns it Were a species of convulsion. It is excited, as is Welli noWii, by the impact of subtilo und spicular bo dies upon the membrane of the nostriis, ulso by urinous spiriis, sine titillating poWder, the Solar rnys, and Othor externat causes. It is excited also by internat causes, as When anything Stops up thelitile foramina of the cribrous lamina, or the litile interstices of the medullary substance, or the Winding channeis of the corticalor cineritious substance, as may be known froin the effect produced ; for Wheu the pituitary substances Whicli clogged the paris are expelled by the aut os sneeging, the brain is immediately quiet, and composes iis cortical tori tuto their due order; and the lungs With their vesicles do the fame; Which yet nei ther

tion of the viscera. How this is dono may be shewn is We tinelar granted the animatory motion os the brain. That the dura mater is evidently contracted at the moments of SHeeZing, is alaci considerest unquestionable by ali the authors I have everread; for it is perceptibi e to the senses os fouet, and sight in the case of persons struch on the head, and Where the brain has been laid open by Wounds and removat of the craniat bones. Besides, e very one knows that When the brain is Somnolent, OrWhen, RS in a great variety os maladies, it, together With thel ungs, begius to be iners, it is resuscitated to the performanceos iis proper motion by the application os urinous salis titillating the nostriis. Τhis then, as I have said, is the highest

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degree of excitation, and consequently of constriction and expansion, belonging to the brain and lungs. All other excitationsare tesser degrees of the fame genus, ariSing 1 rom Similar cauSes, that is, Dom tho contact of air and effluvia. These tesser de-grees Ue may infer Dom the superior Or highest; so that When-ever the air is draWn ita, there is some inciting substance that moves the brain to persorm iis reciprocations. The reason is, that in compotin des the fame effect cannot be Obtained excepi mediately, Which in the more simple substances is obtained immediately. I do not say that the air is the cause of the animation os the brain, hecauso it is at the option os the bruin todraW in the air, or to animate. But When it is the will of thobrain that the air should be inspired through the nostriis, thisair becomes a Lind of conjoi ut motory and impulsive cause of the continuation os iis motion, as We had occasion to say of the friction os the nerves issuing Dom the spinat sheath, Whichfriction is a subservient cause. This excellently meets thequestiolis piat by Boerhaave, Where he says: Why is there so

extensive a communication belWeen the inferior of the nose and the muscies of respiration 8 . . . Does ΠOt Sueeging excite und

42. The mammilla processes are so thin and smali in the human Subjeci, and their roots are nos extended so Widely into the medullary substance of the brain as in brute animais, be- cause the human brain is not intended to be so excited by externat causes, as the bratus of irrationat animais Whicli live under

the guidance of their instincis, and are stimulated to act by allcauses; by the internat, or those proper to the body, and by

human brain is pondering reasons, and directing the rationalmiud to them, it destres to be at rest, and to draW breatliquietiy, as is usual With intense thiukers : it also, in order

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that it may be lest to itself, deprives ali tho organs of their acumen, and consequently also the olfactory organ; Iest anythingshould disturb iis OWn process of analysis, and prOVOke a greater influx of blood than sueti a state of the brain then requires. ΡοWur therofore is gi ven it to draW in the air through a shortor passage, Without iis coming in contact With the sensory fibriis, namely, through the mouili, disserently Dom What we find to bothe case With Other animais. But brutes, as they have noreasoning poWer, in Order to avail themselves of ali the cause of their instincis, and to apply it to themselves and their oWΠnature, me under the neceSSity of continuatly expanding the acuteness of their Sensations to the ultimate degree, so as toprovide sor themsolves out os present objecis. Heuco it is thatthey are endoWed With such exquisite organs of smeli, and with such very ample mammillary processes, occupying thegrenter part of the base of the brain, and ontering tuto tho

VII.

43. But as the animation os the brain floWs by a naturalnecessity into the respiration Of the lungs; and as there are amphibious animais that live alternately in the Water and the uir, or that alternatoly draW and retain the pulmonary breatli, heuce I fuit anxious to examine the bratus Of such animais, and al

of the brain come in VieW, shining conspicuousty through the

dura mutor.

44. The accompanying figure represenis the upper Sursace of the cerebrum and cerebellum. This sursace is covered With

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R membraue Or dura mater, Whicli is in close contact With thesia mater, and surround s it, but does not anyWhere adhere tothe cranium excepi beside the orbiis, and Where the nerves and blood-vesseis mine their exiis and entrances. The Orbiis are placed about oo. Under the dura mater, in Which no arteriesare visibio, blood-vesseis ruit in most beautiful Order, und arehelter feen When this transparent covering is removed. The

Whicli uni ting, descend to the spinal marroW. When the dura mater is removed, the Sinuses are talien aWay, for the lalter are

compri sed With in a duplicature os tho dura mater. There is also an extremely fine membrane, Which besides the above, in-vesis the Sinus Within, and is seen When the dura mater is pulledaWay Dom the brain. The arteries have tWO Origitis, One at thebase of the situli, under a Lind of osseous barrier, Whicli is

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identical With the posterior clinoid process, OVer Whicli theycurve, and this, at the fides of the pituitary gland, be rethey climb the cerebrum; the other, in the orbiis, belo oo),

Where the dura mater, as me have said, adheres to the bone.

The sirst-named arteries, Whicli come frona the base of the si ullor hom the internat carotid, ascenning ut the fides of thebrain, Whieli are not represented here, reunite principalty into

that the semicircular subtense passes as an intermediate betWeeuthe blood-vesseis derived Dom these two AOurces, alternatelyreceiving the blood Which also alternately sows in; so that Whenthis bird respires the air, thero is a largo influx of blood throughthe carotids, aud a large esslux through the laterat sinuses staph), but When iis respiration is interceptud by the necti being heldunder Water, there is a large influx through the orbitat arteries, and a large efllux through tho divaricated rostrat sinuses silo), underneath Whicli the olfactory nerves proceed, in the middie of the semicircle m, m, ' n), Whicli lends to each iis oWn litilechannei, Whether the litile branches soW in Or Out. Τhus it is provided by a Wonderfui expedient, that the bra inisself shali bu the uniting medium belWoen the motions of the beari and brain, Whicli medium is supplied in land animais by

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the dura mater attached to the cranium, and a litile distant om the sursace of the brain. VIII. 46. But hithorto me have derived the series of confirmatoryarguments Dom anatomicat investigations alone. But the realtriath is, that anatomy dictates nothing more than the probability of our position, and is dumb excepi in cases of Vivisection. For although the connections of the Vesseis, nerves, and Rirtubes, coincide With the influx of motions, stili they do so onlyin reserenue to the judgment of the mitid, Which should itcheristi any other preconceived idea, it is With dissiculty per- Suaded, unless the contrary be demonstrated to sight and totich. It is necessary then that the fact should bo exhibited to the senses by opening the situli. But perhaps you Will say, Why est this circuitous and Operose deduction When a single living example Would setile the matter. Be it so; yet the subject upon WhichWe enlarge, is Well Worthy of our patiis; for it is only by the

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tion os the organs immediately subservient to respiration, as thelaiynx, t 1achea, bronchia, iungS, pleura, diaphragm, DerVes,

from patia, or torpor, attend to the changes that talio place in the inferior paris. Near the temple Os Tellus, noW the churchos St. Pantalleone, bulli on the si te of the liouse of Cassius, in the street Suburra Within the Carinae, I linem a Woman 70 years old, Who suffered under severe asthma With continuat cough, but Whenever She strongly compressed the top of her head With both her hands, the asthma aud catarrhat cough immediatelyceased; and this, So long RS the pressure Was continued; butWheu fhe WithdreW her hands, both symptoms immediatelyreturned: whicli might be the case many times in the course of the day. In this instanee, Was the pericranium assected and supported by the Strong compression of the hands, and was theeffect propagated to iis origin, the dura mater; so that thelalter acquiring additional poWer and tone, tho motions of theliquids in the inferior paris Were botter directed, and thus theasthma and cough immediately ceased J Assuredly a more pro-

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bable Way os accounting sor the facts cannot Wolt be conceived.V Specimen Quatuor Librorum de Fibrci Motrice, lib. i., cap. V., ud suu Unless perhaps the joinings and futures of the cranium Were SO IOOse, fas Was found to be tho casu in tho head of Pascalafter his death), that by the assistance of the hauds, the patient forced the dura mater attached to the futures to perform iis natural office in assisting in the elevation of the brain, thedilatation of the sinuses, and the duo influx of blood thereinto. 49. Similar cases occur in those Who astor the application Osthe trepan, are destred by ali skilful surgeons to holii tho breath Strongly, by Whicli means the collected sanies is extruded, or is preVented Dom passing inWariis. Thus Nuck says : Is thebl Od Or sanies does not come out spontaneouSty, the dura mater must be depressed by the decussorium,' and in ordor that the mattor collected in the cavlty of the cranium may the bettersirid an exit, let the patient close his mouth and nostriis, and hold his breuth, and theu When the brain is compressed, themore deeply- sented matter Will rusti Out.' erationes et Emperimenta Chirutaica, exp. V., p. 21; 12mo ., Lugd. Bat., I 692.)Aud Boerlinave says in his aphorisms On Wouniis of the head, and On the trepan: Sueeging and holding the breuth Will holpthe patient during the operation of elevating depressed portions of the stiuit.' horismi de cvn. et cur. Morbis, Π. 271.) Andagain he says : Deep and stoW respiration indicate an Obstructed brain, and the diseases attending or solioWing it, ascoma, lethargy, delirium,V kc. Inst. Med., Π. 986.) I sorbear

50. In ali bratiis obstructed by any sanies, viscid phlegm,or Other malignant impurity, the faculty of reciprocation is similarly impuded, either in Whole or in pari, aS in apopleXy, epilepsy, and the like, of Whicli an excellent account has been

An instrument Which by gently pressing on the dura mater, CauSes an evacuation of the pus collected belWeen the cranium and the beDrementioned membrane,

through the per ration made by the trepari. V James' Medicat Dictionary . - Tr. 9