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structure, but occupiod horizontalty the apex of the ogg. Thochicli, with a large head and oblong spine, the lalter eouered by the ruptured sollicie, Was immersed as heret fore in the colliqua mentum, of Whicli the quantity Was noW increased V n. 242). This, as I have suid, is the first of iis innocent ages,-Rn age in Whicli the spirituous fluid truces out the sirst stamina With avioW to form tho litile bratus and medulla spinalis, from Whichali tho other members are likeWise formed. The mode, hoWeVer, in Whicli these paris are respectively delinented oach Dom thetime os iis sirst inception, We shali on demor to utilald in the Paris oti tho Brain and iis Cortical and Medullary Substances. For every spherule of the cortices substance is a cerebellum in iis smallest typo, or is like a minimal brain, through Whicli thospirituous fluid is conveyed, and from Whicli once inchoatod allother things 1low in their proper sequence. MeanWhile this ageis to be rogarded as the 1irst, or as the one in Whicli the Osrspring 1irst designs to visit the externat World enjoyed by iis parent, and by the robirth of the parent in iiself, to secure the immortali ty of iis Lind. The period that precedes, Or that exisis bufore it comes into the ovum Or uterus, is not One that is proper to itself, but common also to iis parent; and When Domitiis it has passed into the periods and degrees proper to iis OWn nature, then the mollier represenis to herself the os pring asstili in horself, Or as stili existing in the period common to hor- suis. This appears to be the reasOn Why she does not regarither offspring as being as yet the object of that nurturing caro and love, Whicli is asterWard the connecting boud belWeen tho
274. The seconii, when by the messium of the purer blood, thesimple tellure of the heari is provided. This state is tho second
as the brains have impartod sufficient longili and continuity to the spinal marros, and have thus Inid a sussiciuntly solid soli11-dation for tho futuro odifice. Aster this ali the operations continuo to bo carrien oti by the most regular laWs ; thus We findiliat in tho nexi placo there is nothing Whicli the bratus so mucti destre in the Way os an associale and helpinate in their tash, as blood and a heart. Consequently, the hoart at longili dorives iis origin Dom fibres rolled Osr Dom the elongated cicatricula,
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275. The formative force there re issues sortii Dom thospitio os iis litile medulla as Dom the firsi and goiden age of iis existenee, Whence it passes into another theatre Os action, and there reueWs the dispori of iis determinations mitti thevieW of extending them over a still Wider range; for Whichreason it sirst transcribes iis power into the heari, Whicli is designen to serve as the regulator of the future body, and Whichlies moreOver close to the spinat sheath on the ouisi de of the thorax, clothed by the medulla With fibres emulating the muscular, and adapted to the exercise of their proper forces in proportion as the blood receives iis fixation in iis ultimatu
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mence When the heari sirst begitis to appear, and the blood is circulatest in a simple orbit, of Whicli subjeci I shali speah in
almost naked on the ouiside of the thorax, are on the laurili Orfifth day covered over by a sine tunic, and gradually after theseventii day are concented Within the thorax' n. 246). Again he says : On the 5th Gy of incubation, One may Without dissi-culty seo that the right ventricle of the beari has approachedio tho lust, and is lying upon it ;V but the heari, as he Observes, is not of a conical figure utitit ustor the sevcnth dayV Ibid. The reader should here consuli the works of Malpighi, in Whose figures he Will have an opportunity os admiring nature'S play; after his Delings os astonishment have been excited by a perusalos theso illustrations, he Will be refreshed With the pleusing nature of the c1rcumstances Which tahe place at this stage of existenco. This third age is more particularly that of the purerblood, as the second Was that of the spirituous fluid. In regardio timo, it is longer than the others; in regard to space, the Operations are more Widely extended; in regard to heat, thereis a fuller supply; in regard to appearance, the partS Rre more prominent, as may be Seen by holp of a lens; in regard totouch, they are Stili very sost anil tender; this age being one iuwhicli a corresponding treaiment is required. The Corculum Ortitile heari is uoW seen to be traversed by the purer Or White
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humor, and 8Ometimes a humor Of the color Os sere vine-leaves. . . . The norin Sent UpWardes Certain considerable branchus to the
are not visibly produced Or excluded Dom the sinuses of the hoari illi tho Sth day, nor can they be excluded be re the Ventricies of the heart have coalesced, and besore the pulmonaryartery is sent Out Dorn the right ventricte, and the pulmonaryuoin is continued into the lest. Thus the first age of the lungsis the second age of the heari, or the third age of tho brain and iis spinal marroW. Whence it is evident that there is uot asingle member of the body but passes through iis oWn distinctstages Os existence. We are here hoWever treating only of those generat ages pertaining to the body, Whicli are severalty passed through, froin the time of the existence of the sirst living potnt, according to the ordor of the fluids. How or by What cause this most simple type of the heari, orthis three id vesicle, causes iis Separate paris succe88iVely to combine into One,-sor instanee, hoW the right ventricle of the heurt tWisis bach upon the lest, fixes rOOtS, Superinduces muScular crusis, and knOis the heart up into a cono; hoW the right auricie, Whicli is asterWards fimbriated, and likeWise the lost, Whicli arises out os uo visibi e trace, extend Over their respective ventricles, and both become uni ted by an intermediate septum; hoW the foramen ovale is opened froni the right into tho Iost auricie, Whilo the right ventricie, Which hitherio had given no
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Sigia os opening into any place, noW sorm S a communication Miththe pulmonary artery, and Dum that artery sends the litile arteriai duci into tho uorta; und finalty, hoW the lungs, Whicli areextended into the trachen, preclude the influent uir Dom any necess to the hestri; are nil questions the explanation os Which Idesign to Walve. Nor shali I say Whether in so doing it be bo- cause these ure subjecis more os curiosi ty than utili ty; or because in explaining arcana Os this nature I should nos appear to thereader sufficiently clear or Weli supplied With facis, Without 1irstimparting to him an experimental knowledge of the organign-tion aud functions of the severat members, and of the variety of the besoru-metitioned circulations of the blood, for Whicli seu
Generat, because the particular paris are not yet formed. Only the generalouuine ut 6rst is sketched, and hence Only such materials for the completion of thebody are required as are of this generat nature.- Tro
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279. There are three generat fources of motion, On which authe particular sources depend; sor What is generat is requisite inorder that there may be a distinet particular: the generat in thepresent case is, the brains, the heari, and the tuus. The motionos the brains is called animation sese Paris II. and III.), and theuction of the spirituous suid depentis uson it. The motion of the heari comprises systole and diastole, and on these the circulationos the blood depends. The motion of the lunos is called respiration ; on this the circulation of the purer blaod principally dependa. Aut since the purer blaod is intermediate belloeen the spirituous id and the red blood, there fore iis circulation deperiri upon themotions of the brains as weli as of the lunos. On this subject thereader Will sud numerous remariis in the sequel. The motionos tho lungs Will bu discussed in Ρart VII , on the Tongue, Trachea, and Lungs.' In the meantime, Willi respect to the circulation Os the purer blood, See n. 359, Seqq. 280. Durino the formation of the chich or the embryo, and previsus to eaeclusion from the eis or the womb, the animationos the brains is coincident milh the systole and diastole of the heuri; but afler the lunos are formed, and the chick or embryo is born, the animation of the brains dissociales isset from the motion of the heari, and conjoins itself with the respiration of themus. On this subjeci I must det in the reader sor some litile
time, for uiatess these particulars are confirmed by actuat facis, We Cannot move a single step tOWard the theorems Whicli are tofollow in tho present Ρart. The truth of this article hinges onthe solioWing propositions. I. That there is an animatory motion of the cerebrum, und With the cerebrum, of the cerebellum and spinal marroW, Whicli motion has been called by Some Ruthors a systallic motion. 2. That during the period of formation, this systallic motion exactly coincides With the systolicmotion of the heart. 3. That after the period of formation, Or
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after birili, it conjoiias itself With the respiration os the lungs. 4. Diat that it again conjoiias itself With the motion of the hoari
Wheneuer it returus into a state similar to that Os formation, OrWhenever the lungs cense to respire While the heari continues tobent, ns in cases Os drOWning, suffocation, Obstruction Os thegullet, trachea and bronchia, in lainting, and so fortii. 28I. I. That there is an animatory motion of the cerebrum, and with the cerebrum, of the cerebellum and spinia marrOW, Whicli motion has been culled by some authors a Sy Statile motion. SO far as I may sortii a conjecture froin the writings of the learned, there are some WhO do not deny motion to any viscus in tho body excepting the bratias and their medullae. Τhus the stomach and intestines have a peristallic und vermicular motion; the lungs, an alternately expanding and subsiding motion; the heari, arteries and vetus, a pulsatory and circulatory motion; the neighboring members in the thorax and abdomen, n motion in common Mith those just mentioned; and allother members a muscular motion : While the braitis ure allowed Scareely any motion but that of the arteries as they slighilyrnise themselves above the levet Of the sursace. ΝOW a mn-chine lilio tho brain, Whicli talios such a loading part in ali theessoris, forces and actions of the body; Whicli is unweariod in iis Operations; Whicli never censes Om the duties and cares re
sibros. The truth of this circumstance We are SheWn by OXperi- ence, and we are taught it likeWise by the relation Os causes. Nor is there any right to expect that We can eVer arrive ut a true knowledge of the cerebrum and cerebellum, the nerVOS, In IS-cles, and viscera of the body, Without sirst admitting tho factos the animation and alternate expansion and contraction Osthe former. Indeed, there is not in the bratus and their various procesSes a Single furroW, ridge, cnVity, si bre, artery, Or Vein, that does not indicate anil most distinctly prove, that both thebraitis and their medullae are formed in motion and lar motion. Let us then once set the machine in motion, and the use, effect
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and en d os ali iis mombers Will be evident to the sense8. In cases in Whicli the head has been Wounded und laid open, thedura mater, and more especialty the Subjacent brain S, axe Seerito be in motiou. Ridloy luid bare the dura mater, and after Opening the longitudinal sinus, and Hlowing somo of iis bioodio eScape, detestted a motion exactly synchronous With the pulse of the heart. Anatomy of the Arain, chap. vi.) Ρacchioni declares that the motion Of the dura mater is not simply pulsatile; although, according to AlayoW, When the cranium is perforated SO that a portion os the brain comes into vioW, the bruin itfelsis Seen to swell, and then to Subside. era, p. 152, 153; 4to. Rome, 1741.) Where the coronat spine and the crista galli os the ethmoid bone decline into the plane of the cranium, theyure succeeded by the front portions of the frontal bono, Whichon the concave side, facing the iobes of the cerebrum, aresormed into such hollows, that the gibbous projections of thentiterior lobes of the cerebrum can advince tuto them anuthere malle their abode. In these hollows, and round abolitthem, the arteries of the dura mater Rre seeu impressed audesfigied upon the bone. The fame is the case in the large parietat bones, Where beside the litile canals Whicli are carvedout for the longitudines und the two lateria sinuses, there are
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thum. There is likeWiSe a Space belWeen the membrano pro- per or proximate to the brain and the dura mater; in Ordor that tho brain, is capable of elevation, may be elevated. Thereare also fibres like muscular fibres at the fides of the sinuses, and in the sinuses themselves there are chords that exhibit a manifest motion Originating Dom the bratu. There is also in places a fibrOus substance belWeen the corpus callosum and the falx, of Whicli Willis mines mention. Cerebri Analome, cap. Vi.).
The fluxion of the tendinous fibres, of Whicli tho falx, the
transverse septum betWeen the cerebrum and cerebellum, and
the dura mater Dom the falx to the periphori es, are conStructedand Damed, politis out not Only that there is a motion, but also What that motion is. Τhe very si usos themsolves, and ali the arteries and vetus Of the brain, ure disposed according to the Stream of that motion. There are ventricles and hollows, Whichusford the brain room Wheu contracting, and close When it is opening, and whicli enable the offect of the action to bucomedeterminod toWard either the interiors or exteriors. There Rrealso chiniis, such as is that of the third ventriclo, Which Wouldbe perpetuatly closed uuless the cerebrum Opened the fissure into the space benenth. There is theres ore somo internat notio in the bratiis, Whicli, according to the experience of Ridley, inny even be perceived by means of the fingors. Anatomy of the Arain, Chap. Vi.). In a Word, throughout the entire subric os the brain, thero is nothing Whieli presentes itsolf to Observationbut tentis . to confirm the faci, that there is in it a generat unimatory motion. Without motion tho blood could uot bo expollod froin the largor trutilis Os iis arteries into the smulier, much loss could tho bland juice bo expre8Sed in So large a quantity into tho ultimatu capillaments of the cortical substance and of the fibriis. Moruover the arteries and vetus in the bratus,
the brain iiseis; not arising Dom the hestri, beenuse Mithout auxiliary fibros or motory rings round iis arteries and vetus, this organ could uot extend the force and sphere os iis action into the very penetralia of the brain iiseis. For What I have atready Sald On the muscular coat, see n. 217. The blood moreover in iis passage toWard the interiors of the bratus through their me-
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animal nature has so providently and ingeniousty constructed sor it. The brain theresere is formed in motion and for motion, and as I have above observed, let us Only set the machine in motion, and the use, end, and effeci, of iis severat puris Will ut
Onee bo made manifest to the SED SES.
A motion similar so that We have here called the animatory, is observabie in the rudimentary brain. I have Osten re-marhed,V says Malpighi, as a usual piece Os nature'S play, amotion present in the gones, by the coming and going of Whicli, the areas and cavities Os the carina Were either e larged Or Oblitoraled V n. 243 . But the proximate cause of the animationos tho brains is a matter of dispute among the learned. In Paris II. and III., I shnil shew that it arises Dom the animation of the cortical und cineritious substanee of the Spherules, and thus primari ly Doui the foui itself governing the motions os iis oWn fluid. The reader may here consult n. 177, Where it Was potnted out that the animatory motion of the brain dependson the cortical spherules, and lienee as it Were tapon an infinite number of titile hearis, one of Whicli is prefixed to euch of the
282. II. That during the period of formation, this Systallic motion exactly coincides With the systolic motion of the beari. Os this me may have ocular demonstration by merelyinspecting Alalpighi's figures in his litile frontise, De Formatione Piali in ovo. We are there Ahewn, that from the last vesicle of the heuri, the blood seuds out three principia branches rurining to the head only, Whicli meet together and form a largercanal; that this canni renchos round the extremit of the Carina,