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

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Whicli is very White, solid and less juicy, and is termed thum dulla of the cerebrum and cerebellum; Where re the medulla clearly appears to arise primarily Dom the cortex, both in the appendices, the ventricles, the crura, and the medulla ob

the medulla proceeds DOm the cortex, With iis proportion, subric and divisions. Ibid., n. 9I.)II 5. I do not knoW hoW any person Who admits these facis, and acknowledges the influx of the bl ood-vesseis into the sub- Stanee of the cortex, cari deny the continuation Os the fame into the fibres of the medullary substance, UnleSs he Chooses to Suppose an interruption os continuity, and a dead stos; but asthis is repugnant to nature, Whose lise consisis in the continuityos her paris, and thereby in the perpetuat circulation os hors uids, there seems to be no reason to descend to any Sueli VieW. And yet Ri sch seems to intimate as much, is not openly tostate it, in ordor that he may alter the glandular character of the cortex tuto One that is purely Vascular. BOerhanVe replieS : But Whuthor tho minute ultimate t gs of the cortical ves-self become by direct continuation the origin of the fibrous SubStanee of the brain, . . . as Would appear from What Ruyschlias Stated, is a question uot decided by any valid argument,

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Ac. Ac. Vbid., n. 94.ὶ There are indoed numerous vesseis that penetrate beside and beyond the cortical substance into the

medulla , but they go partly to the cineritious substance thatis hiddon aud scatiored about in the brain; partly to the diverticula ann receptacles formed for the purpose of giving the brain iis generat poWer of extension; and partly to the littJu fheatlis

of the fibros and fascicles; as Will be seen in Ρart IV., on the Arteries and Veius of the Brain. MeanWhile the render Will See an abundance of Ocular testimony amassed in Pari III., onthe Medullary Substance of the Brain, ali tending to fhew that the medullary substance of the brain proceeds Dom the cortex. II 6. Therelare the cortical substance is placed in the middie, or in the last term of the arteries of the brain, and in the sirst term of the fibres of the bruin, so that this substance, like thetWO-hended Janus, loolis backWards and forWards; backWard Ontho side of the arteries to the crasser blood, but sorWards onthe fide of the fibros to the spirituous fluid, both of Whicli unituin a manner in the cortex as their common and principes substance ; and this, in order that effecis may return to their causes in a Wonderfui circle every time that causes tend to their essecis; and vice versa. But to proceld.

117. Consequently in the midiae, in order that it may be ableto ertraci from the blood the purer essences and animal virils, and transmit them immediate into the snest medullam flument' and so into the nervous flaments of the bo . There can be noWorthier subject Os enquiry than that presented by the folloWing question : What do the medullary 1ibros of the brain, and in their turn, the nerves of the body, extraci Dom tho blood 3As this is a matter requiring the deepest investigation, We mUStdWeli upon it someWhat ut tength. The examination Os thecortex atone Will assord but litile light; tho examinatiou of thebrain Will give us more; and of the nerves of the body, stili more: hence We must follos the subjuct Hl the way tuto the

found the truth; for is Wo have, nil our succeeding Paris Ontho Brain and the Body, With thoir infinite particulars, Willrange themselves by iis fide; and it is DOm a caresul examination of these particulars, for I have gono through the wholeanimal system in the fame manuer as I have here gone through

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tho cortical substance, and in the nexi Part through the modullary substance,' that I have at last gained this universat notionos tho circulation Of the animal spiriis.118. I say that the substance of the cortex attracta thesurer ESSences Or animal spiriis Dom the arterial blood of thobrain, but nos Dom iis concomitant serum, and transmits theminio the subilest passages of the fibres. In order to sollow thotruth of this assertiou, it is necessary to en quire into the Cha

their Way to compose the vertest substances of the cortex. 3.

tical substance, and so flies On in to the corresponding litile canalos cach fibro. 4. But When dividen a second time, or into the purest spirituous suid, it penetrates into the subilest threads of this cortical spherulo, Whicli constitute the Sursace, and so ispoured into the sursace of the fibres of the above cannis. 5. The medullary substance of the bratu and the nervous substance of the body are so framen and Woven, that the Whole of the truly Sanguineous globules, When resolved tuto their paris and elemenis, enter them distinctly, and ruu through their sub-Stance ; so that nothing of the genuino blood is tost besoro ithas performed a use in the innermost penetralia of the animal

119. Fιrat , the blood draWn up by the brain is soster, lighter, more resned and fluid than the rest of the blo d. Τhis fact is perfectly plain Dom the character of this biood, usinvestigated by the best anatomisis. Respecting the nature Ostho blood that is supplied to tho brain by the carotid und vertebrat arteries, and respecting the disseretice belWeen ii and alltho rest of the blood, see Boerhaave, Inst. Med., n. 223-235,275. And respecting the lymph of the brain, that it forins

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rial blood stili fluid, and of a boautis ut light crimson color; Whilo the blood in the sinuses of the dura mater had coagulated, and Was os a foui blachened hue, contrary to What We generallysiud in tho arterius and veitis of the body : a plain proos thattho blood of tho brain is more impregnated With spirit, Whicligi vos it iis genuino fluidity. And this follows as a matter os

ing the peculiar blood that it is to expend upon the fibres; asWe have demonstraten in the preceding Chapter on the Motion of the Brain; and in Vari I., on the Blood, the Arteries, the Velias, and the Heari, D. 227, 346-350. 120. In Pari I. We also fhewed that the genuino blood is intrinsicatly and naturalty sost, yields to the compreSSing VeS-

culation of the blood, the arteries Were Dot Wider than to alloW8ingle particles of blood to pass through them Without impediment. . . . I SRW that many of the particles Wore rendered tWiceas long as broad, and that Oach of their extremities appenred acute.' Arcana Naturae Delecta, in Oper. tom. it., p. 161; See

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diameter Os one globule of blood, but Dot even the thousanditi part of that diameter, and scarcely even the millionili pari, Sothat unless the bl od-globule sussered itself to be bent, and tobe divided into minuter particles, transpiration Mould CORSO, and nothing Would remalia but a solid, euti rely destitute offluid; hen e there Would bu an annihilation os lise, since lise consisis principalty in conspirability and perspirability, accord- ing to the declaration of Hippocrates. From these observations the nexi preliminary proposition solioWs. I 2I. Second*, This biood suffers itself to bu readily divided, through degrees corresponditig to the divisious whicli the litile

arteries Undergo On their Way to compose the vertest SubStances of the cortex.-Although this is a consequetice of the former State-

clue in the living labyrinth. With respect to the divisibilityof the blood, Wo have ut ready tres ted of it in sufficiunt dotali in

other, breali aWay and Separate, but these Amali globules, SiX of Whicli constitute One perfect globule, Were much soster thanthose Whicli constitute a globule of beer Or Wine.' Arcana Naturin Delecta, in oper. tom. it., p. 8.) Aud again he Says, that he has seen a large number of globules of blood eastly dissolved during their protrusion through the narrOW channeis Ofthe arteries, and that Which Was previ Ousty a single globule, Separated into fix distinet globules. Ibid., p. 36. In another

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place he relates, that on adding the yellos Oil obtained by destructivo distillation frona tho bark of china china, to a portion Osblood talion sporn his thumb, ho could most distinctly observe in cach of tho blood-globules, that they consisted of other dis

pure blood in retoris and phials, changes into species of quite adisserent character, as into Oil and spiriis, and leaves a feWsaline residua; SheWing that When decomposed, it passes intoplements of a disserent nature. Why not then in iis oWn natural laboratory, Where nature lives in her vertest ars, and tho blood 1lows in iis nativo sonuess, Warmth, and divisibilitDWhithersoever the public anu private wellare attracts it; and

particularly in the brain, Whicli in providing for iis fibros

requires Dom the blood so osten iis finest essetices 3 122. That tho rod blood is divisibio not only into si x such spherules, or into the purer blood discoverable by the microscope, but also into blood stili purer, and Whicli me may cali thespirituous fluid, is a fact Whicli is not ascertain able by the sense of sight, though rai sed by the microscope sar beyOnd the range of iis natural poWers. But We ought not therelare to attempt todeny the fact; sor our senses lead us only to the threshold Where nature begius to aut most perfectly and to live most distinctly. It has pleased the Divine Being that w0 should arrive at thispoint by the assistance of ari, and that there human reasOnshould be at haud to tine iis the thread, and to carry it OuWard. Were We theres Ore to terminate Our researches by the limits of sight, We should deprive the mind of ali iis privileges, and hencebo but litilo Wiser than irrational creatures. Τhat there is a further division of tho blood beyond the si X pellucid spherules, or purer blood, We are induced to belleve Dom the vesseis them-

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examine With a poWersul microscope the transverse section Os alitile nerve, as our author telis us he has osten dono, We shallseo that it consists of fascicles distinctly surroundest With tunics; and that caeli individual fascicle is made up Os most minute, tapering canais, and Whicli are compressed because contiguous, and that a clear humor floWs through them, as observabie by the Same magnifying poWers. Through the littio iunios fine lines have been seon Winding in a spirat direction. These phe- nomena Occur then in the litile nerve, to each sbro os Whicli in the fascicle corresponds a particular cortical spheriale; to thelitile canal in the Derve corresponds a similar cavity; to iis litile

lines Or Spires, a similar circumserenoe of mOst minute Vesseis ;

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indicatus that tho globulo of rod blood is a sortes of three vitalsuids, for Whicli three distinct cannis appear to be Constructed, Whicli are successively elevated into Such vesseis RS We see atlast in the nerves. Desides this, the fame discoverer has ostenseen the red globule itself divided into fix glistening or pellucidspherules, and has described Dom his experience the very aut of division; also hoW he saW the Six spheriales combined in a globulo, and discriminaled by light and shade, and suffering them-selves to be extended One by one into an Oval and comparatively oblong form, together With many Other most interesting parti- Culars, calculated not only to persuade but convince us, is Woare disposed to trusi our sight, that this part of the rod bloodis by no means a Simple substance, but Only appears So to thenaked eye; being in reality composed of Six Iesser Spherules, andat the fame time of a quantity of angular Or Saline particles, which wero frequently seen by him through the Same microscope. NON is tho miud ascends a litile beyond the disclosures audacumen of the eye, it must at Onee admit, that it is not contrary to the truth, because not contrary to a belles correctlybased iapon the senses, that this division is not nature s last division in the blood-globule, but that there is stili another,namely, into What must be called the spiritu iis fluid, Whicharises from the pellucid spheriales, after the rejection of themost subtile corpuscules Or Saline copulates borrowed Dom thebosom of the ether, in the Same maniter as the pellucid sphe-rules ariso Dom the red globule. From these and many other Wondersul glimpses of nature's purer field, LeeuWenhoeli ut last passes hom the sphere of sight to the sphere of the mind, Whichis the human ground , and offers the lalloWing suggestions on

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plead Our cause. Whon it is considered, says he, that thered particles of the blood appear by the microscope to be thegrossest os ali that are contained in our healthy humors; and in the meantime, that the serum, the particles of Whicli aremuch Amalter, is again divisibio into corpusculos incredibiy le88, RS may appear froni the grosth of the chieli in tho incubatedegg, Where the humor of the albumen is successively attenuat eduntii it is adaptod to floK through tho inconceivnbly minute vesseis of the litile embryo; and that in the smallest insecis ani ne nity of vesseis of various Linds ure penetraled by their oWn

peculiar humors; and that fur sin alter creatures than even theSOinSecis, are discernit,te in humati semen When this is consi

Observations are suffcient for the present to convince VS, that

the red blood-globule suffers it self to be resolvest uot only intosix spheriales, but also into the principies of these spheriales, in saet to bo dividod utitit it cati floW through the minutest pa8SageS, or the eanais of cannis, in Whicli, although there is nored, beavy, sluggisti blood, beset With saline diast, yet the betteresseiice of the blood stili rem ains, honeo the blood is there pureaecellence, or the eminent blood, and tho vosset also whicli it permeates is similarly eminent. I maintain that it may bedemonstrated,V says Ruysoli, that the extremities of the littio arteries degenerate in various places Without any intermediate substanco into vesseis of a different character. V Ρari II., Π. 86. Τhis suid, raisod to the third degreo above the red blood, I Would denominate With the most os learn ed an atomisis the animal spirit. 124. Third . This biood, whon dividod a si si time, or into the purer blood, passes through the litile bosoni or fine mi dille

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bed of each cortical substando, and so flies On into the corresponding litile canal of each fibre.-ΤO use a compRriSOn, thepurer blood passes through the cortical substances into thesibres, much in the fame manner as the red blood paSSesthrough the chambers of the hoart. The pye indeed has notShewn that there is any cavlty in any individual part of the cortical substance, for nil the observations upon it have been madeaster the brain has beon bolled, consequently When the cortical SubStanees are collas Sed, compressed, and juicetess ; and is theentire sursace and bulli of these is not presented to the eye, hoW much less can be the minute ventricle that it contains. Stili that thoy are furnishod with a corresponding ca ity may doubiless be conjectured Dom the faci, that these substancesare nearly ovat spherules, and as it Were nodules and acini. They are os an ovat figure,'' says Alalpighi, but compressedali round by the adjacent gland8. . . . But these cerebrat glandSare seen With difficulty in the ram brain, even though it be thelarge brain os perfeci animais; because they are lacerated by tearing aWay the pia mater, and their conterminous limits are

n. 76. Vieusseus Observes: The cineritious SubStanee . . . Wheu closely examined through the microscope, is seen to becomposed Os innumerable globules, ali combinod together, andio a certain extent of nn Oval figure . . . . Even is they Rre