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bolow. It is Woli linown that tho spinal marrow transmits iis biood Dom iis cervical portion to the vertebral vein, Dom iis thoracie portion to the vena agygos, and DOm iis loWer portionor cauda equina, to the lumbar vein. NON let us examine tho vena agygos Whicli receives the blood of the dorsal region. 26. The agygos or vena Sine pari in man, is situated along the vertebrae, betWeen the membranes of the pleura, and derives iis biood Dorn the sinuses and Veins of the spinal marro .
But ouiside the vertebrat sheath, it receives the bl ood Doni tho Whole spiratory seld of the Iungs, as Dom the right and lonintercostes muscies, froin the vertebrat muscies, Dom tho dentatiand pectorales, hom the diaphragm, through Whicli it ascenus at
os influx sor the two coincide; consequently that the spine, Whichequalty With the brain is the mover and dispenser of iis oWn proper blood, moves systallicatly With the Iungs. That the spinal marroW tines in and se ds out iis biood at
or Whicli insinuate themsolves into it: and Dom the distributionof the sume blood over the proximate membrane, and OVer thebeginnings of the nerves Which go out through the Very notches by Whicli the arterial blood enters and the venous deparis; Domthe passage of iis biood-vesseis in a Lind of gentie Spire, conformably to the reciprocat contorsion of the spine; So that of ne
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in Whicli moments every branch Without the vertebrae that receives the blood, in stiori, tho intercostat vein With the recipient Vena azygos,) disposes and opens itself to receive this neW Supply. And because these tWo motions are coincident When the muscieministering to the inspiration of the lungs expelf the blood, itfollows that they cannot differ in their moments Or interVal8. And this suems to be the reason Why the intercostat arteries comeoir Dom the norta at right angi es, and why the intercostes vetiis
27. That the trutili of this volu sends out iis biood into the Superior cava With Whicli it inosculates, exactly at the fame intervias in Whicli the bronchia aud trachea, or together With these, the Iungs, constrict themselves, is indicated clearly by the curvature of the agygos around the bronchia, and by iis intimate union With the fame paris, or mitti the trachea, by the fibres and Vesseis that penetrate it: as also by the semi-sphincter With Whicli it is furnished ut the place of inosculation, and vhicli is supplied by a particular nervo derived Dom the family of spinalnerves; respecting Whicli subjeci spe Morgagni and Lancisi. 28. And that every branch of the agygos admits iis OWn proper blood at the samo alternate intervias in Whicli the trunkadmits iis oWn blood; that is to say, at the times When the lungs
perform their inspiration, or the cineritious axis of the spinalmarroW unsolds itself, is evident from the nerve that enters and occupies them all. For the intercostat nerve, Which, as above
observed, enuelopes the carotid and partly the jugular vein, herealso goes to per rin the samo octice. Thus the said nerve puls rth a trunk in the nocti Dom both iis inferior ganglionio plexuses, Whicli frunk divides on each side into branches, about thelaurili or fifth dorsat vertebra; and these branches asterWards
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that it persoruas in the carotid and jugular vetus; ibat is to say,
it disposes these vetiis to a movement through spaces at a similar
That this Derve itself is moved, and can move the branches that ii embraces, only ut the intervias in Whicli the spinalmarro mOVeS, We may infer DOm the mere description of it. For the spinal nerves, excepting the srsi and the three last, immediately at their exit Dom the spinal marroW, produce Smallgangliosorm tumors, DOm Which tWigs and shori cordes are sent transversely to the intercostat nerve; DOm each, sor in Stance, in the Deck there is sunt one simple cord; in the thorax tWO, One DOm the superior, the other Dom the inferior part of thelitile ganglion; and again in the lumbar region Only one. Os
the politis of exit, like barleycortis, together With the fibres and first beginnings of the nerves, and together also With the twomeninges, and With certain tWigs containing the blood properto them, so that they are necessarily in the fame motion Ofvibration With the inmost medulla; as consequently also is the intercostat nerve Whicli is borti os nil these, and in the dorsal region With a doubie origin. Thus Whatever state of modification assecis the spine, the fame also Will affect the nerve that occupies these litile venous branches, and consequently the same Will affect the vein that conducis the blood to the agygos; and the agygos Will be hept in the fame by the fame nervebeing attached underneath to the pulmonary pipes. The intervalos iis dilatation Will thus coincide With tho constriction of the vetus and sinuses of the spinal marroW With in the sileath, and with that of the intercostat muscies out of it, and ut the Same time mitti those of the litile ganglions that seud branches out froni the fide into this common or great sympathetio nerVe. 29. As the vena agygos derivos to it the blood of the wholespiratory field, so the internat jugular vein, Whieli is the common Vein Of the brains, derives to it tiearly uJl tho blood Domthe muscies of the scutisori cartilage, and Dom the upper Partof the trachea, and 1 rom the muscies that assist it. For this
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Vein descends nostr the fide os the cervical vertebrae, and nearthe Windpipe, as may be seen in Eustachius, Tabul. Anai., tab. X., fg. 1. It receives a large branch from the abovementioned cartilage of the larynx and iis muscies, und a Desii One again Dom the loWest root; it receives also a large branch Dom theright jugular vel , into Whicli severat run, as Ahewn by the Same plate, and Dom the trachea and the muscies that assist respirationand speech. These facts abundantly indicate, in my opinion, that the familiar and natural mode os fluxion of these Velias, is the pulmonio, or, What is the fame thing, that it is that of thebronchia, Windpipe and larynx, Whicli concur every time Withthe respiration of the lungs. 30. Aud it cannot, I thini , he doubted, that the animatorymotion Os the cerebrum and cerebellum, is continued also to the Spinal marroW, from Which in this and the folloWing section me deduce the principat force of Our argument; sor ait these viscera are conjOinen as mutuat appendages by continuous medullaryproce8Ses, by the cineritious substanee, Whicli is concentraledinto an axis in the spinal marros; they stre conjoined also by the blood-vesseis and the tWO membranes, Damely, the dura and pia mater, and by the arachnoid tunic; so that it follows
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longing solely to the brain. Heuce it follows, in my opinion, that every time the bratus animato, and With them the Spinal
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quires), excepi ut the times When the brains animate and thel ungs respire. For Whether We deduce muscular motion Domtho immediate influx of the brains into their nerves, RA Wheu the bratiis exert their active or living force, that is, animate; orWhether Wo deduce it Dom any friction or touch of a nerve in the body; it is here provided, that neither One nor the Other, RS
R CRUSe, Or RS a minister to the principat cause, shali be Wantingio preserve the continuation of the motion, since in the vertebrat foramina through Whicli the above-mentioned nerves sRSSout, there is a peculiar mechanism os such Wonderfui construction, that as Osten as the ribs are raised, a certain SpecieS Offriction strities the issuing nerve; the foramina being compoSed by the meeting of the Dotches cui out in the inferior part of the superior vertebra, and in the superior part of the inferior Vertebra. Thus Whatever the time or manner tu Whicli the vertebrat column bends, or the ribs conjOintly rise, the notuli Ofthe superior vertebra, by reaction and friction, aetS upon onepart of the nerve sent Out, While the notch of the inferior vertebra is acting in a contrary manner tapon the other pari. Thistahes place more especialty in the dorsal region, but not to suchan extent in the lumbar, the vertebrat notches in the dorsal region being carved out more boldly than those of the lumbis. The manner in Whicli this is effected may be even mechanicatly exhibited to the oye. Moreover the ganglionic hodies exteriorto the notches are constricted ut the Same moment, and by a certain mode os contraction operate coriointly upon the nerve8above mentioned. Consequently, Whether the intercostat mus-cles are stimulated to action by the formor cause or by the lalter, or by both together, there can be no Want of an active force and efficient cause in the nervos, and derivatively in their muscies, so that the whole of this region, both Without undvithin the vertebrat case, may unanimousty conspire to producetho motion of respiration. We may confirm these vieWs by a remari able experiment recorded by SWammerdam. We observe,V says he, in many animais, that as Soon as the beginning of the spinal marrow in the cranium is disturbed, ait the subjacent muscies suddenlycontract. And this also happens in the fame manner With respect to est the tWigs of the nerves procoeding DOm the spinal
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34. But ali these things are more olearly and distinctly Seen in multi cord infecis, as nymplis, cate illars and buttersties, Which have indoed severat trachese and pulmonary pipes, and Severat litile spinal marrows or outgroWilis of the brain. Theabove universat and predominant motions cannot but be more distinctly imprinted and repres nised by the fluxion and mutuat communication of the nerves and vesseis in these creatures; sor they live principally under the auspices of the above motiOIIS, because under natural instinet. 35. From Malpighi's goiden treatise On the silk-WOrm Dissert. Epistolio. de Bombyco, and SWammerdam's Work On theanatomy of insects Biblia Naturos, me actualty see by the microscope that the severat dilatations of the spinal marrow in infecis, Whicli dilatations appear to be so many Succenturiate cerebra Or cerebella, exert the poWers of their activity principally upon the litile trachea: for every sueti moleCule or gangliosorm tumor of the spinal marroW produces tWo large patrS of nerves, of Whicli the upper immediately floWs into and operates Upon the nearest trachepe and pulmonary pipes; Whereas in thelarger animais Wo sud them acting sirst upou the ribs, the OSSe-ous and cartilaginous grate of the chest, and so upon the Iungs
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Stan C. . . . On ea li Si de tWo large patrS of nerves are gi ven Oss, . . . Os Whicli the upper pair is sunt to the neighboring trutilis of the trachea. There are . . . thirteen globules or nodules; forouer the first orifice of the trachen, tWo, but litile distant Domeneli Othor, . . . RSCeud toWard the head . . . . The JOWer globules beyond the first ring . . . are Siluated in a lino Dom the Orifices of the trachea. . . . The nodules above mentioned are Supplied
bu minute branches of the trachen; for Dom each of iis orifices tWo branches run toWard the intermediate Spine, and meetingeach other in the middie, generate a mutuat anastomosis, Whieligives out minute tWigs, that closely embraee the globules and the prolongation of the spine. Ibid. , p. 20, 21.) The cavityof the cranium is filled With many paris, namely, With a portionof the spinal marro v, With the extreme branches of the trachen, Ac. Ibid., p. 22.) But the author's figure more Clearly SheWSthe close relationship and consanguini ty betWeen the brain Orspitiat marroW and the trachepe or lungs ; and the render Wili do Wolt to consult it, for he Will theu see With his oWn eyes that
there can be no motion in the One Without the Same motion eX- isting at the sume time in the Other. φ36. In other insecis most acutely examined by SWammerdam, a Similar concordanee of motions is Seen RS in a picture. Tho ramifications of the trachen, V says S Wammerdam, COnstitute the principat part of the lota se ; they exist in immense numbers in the head, breast, belly, and legs, and even in the
sists of three large ganglia Or dilatations. . . . The membrane in-
Τhis Figure so meli illustrates the author's present doctrine, that we have thought it advis te to infert it here. It represenis a portion Os the spinal marro With a tracheal pipe and iis ramifications. ΑΑ is the white exterior part Of an Ovalglobule or nodule On the spinal marroW. B, the inner cineritious pari, curved aboveat C, and Sometimes forming below two appendages at DD, but Whicli are Shori, and in the line of the nerves, EE, Whicli run obliquet y down to the muscieS and joinis; While the nerves FF are sent to the ne liboring trutilis Of the trachea. PPΡPΡΡ are branches of the trachea.- Tro
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. . . VRSt numbers also are suspendest at the fides of the nerves. . . . The dura mater of the brain ... is also furuished With pul
bios Or ephemerus, he snys that iis spinal marrow consists of eleVen nodular tubercles, . . . Rud has a large number of Rir-
37. As the structure in ali these cases is more Simple, and nearer to the nature of the thin g, than in larger animais, Whose viscera must be more elaborately and artificiatly Woven, and their connections more complex, to fuit the concourse of vitalmotions,) so here We may See as in a picture, that the most universat motions of the Whole animal or animating System, arethose of the bratus and the Iungs. For in these most Simpletiving creatures, the bratu acts upon the motivo fibriis of the whole body by means of the nerves in consori With the number-less atr-pipes; but not by means os the hearis, Whicli, disposed under the Iobules of the Iungs, soW mediately and involuntarilywith thoir blood into the motive fibres. Τhe fame is the case in animais that have Only one heari, and tWO lungs, and a continued spinal marroW. For in these cases, every time the bratua is by the nerves iapon the muscies, it summons the lungs toassist it, Whicli superadd generat force to the most particular forces of the brain; as We may clearly see in ali attempis at action, Whether in listing Weighis, making beds, extruding the faeces, figliting, Wresiling, SneeZing, yaWΠing, Speaking Or Sing-ing, expelling the child Dom the WOmb, or any Other est Ort, WhenstraightWay the most generat force of the Iungs is immediatelyso exactly applied to every special force of the brain, that theaction of ali paris necessarily combines into One,-Whicli Without