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any gi ven species, Whether it be n portion, n maSS, n mountain, d Oes not cense to be sali, Stone, or metat, belonging to that species. The fluid consisting Os plano-Oval spherules, Whetherit fili a fibrii or tho smallest filament Os a nervo, a Siphon, OT Rbludder, remaius nevertheless One and the fame fluid. The fame rule holds in regard to ali other things, the division ofWhicli continues, Without any change of Dature, even to their component unitS, Or the constituent elements of that degree. Unless Our conceptions On this subject be clear and distinet, Weshali have Only an erroneous idea of the nature os divisibili tyand composition. The severat single paris of a Whole me ascommon numbers and rational integers, Whicli are homogeneous
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numbers, the multitude and quantity of Whicli, in relation to the multitudo and quantity of the former, are heterogeneOHS. A similar law is obsorved by the blood, tunios, and VeSSel S. Thus tho proceed from Drye arteries to lener and least arteri , and from least veins to Dryest; ali of which are emplayed inconvmino the volumie of red blood, and constitute only one Orderos veraeis.157. There is the fame progression in vesseis of the Secondor G which conum the less compounded blood; and the Samevuin in veraeis of the 'st order, or in the fibres, which convey the
viritusus id. Τhis is a consequence of the former rule. Inregard to the fibres, hoWover, the fame laW does not altogether obtain as in regard to the blood-vesseis. For in Stanee, RS thesibres progress, they do not in the fame manner decrense in Sige, but accumulate into a fascicle, a d hoWever large this fascicle may be, it comprises Ouly fibres of the srst Ordor. The fascicles, Whicli are also the beginnings of nerves, and Whicli in the medulla spinalis are called anterior und posterior, are there congregated into one nerve, Whicli, hoWever large, includeS Onlynerves Of the Second Order. Consequently u fibre is a unit of the sirst ordor, a fasciolo of fibres a unit of the secOud Order,
and a nerve a unit of the third order. In the sirst the unit is determinate, in each of tho tWo Ialter it is indeterminate, inasmuch as they are diminished in the number and multitude of the component uniis, in proportion as they descend into the SeVerat provinces of the body. A similar iam holds in rogard to the spirituOus Or nervous fluid, as in rogard to the fibres. Τhus, for eXample, the very fibre itself, or fibre of the first orderi carries Within it a mosthighly desecated and most puro fluid. But betWeen the firstfibres, or in the spaces interposing betWeen them, a fluid Whichis tess spirituous is carri ed. The fascioles, hOWeVer, Where nobiOOd-VeSSelS Rccompany them, carry With in them a lymphaticor other fluid, Whicli is commonly callest the nervous fluid. Eaeli of these nevertheless is spiritu0us suid, but in the sirstfibres it is pure, in the fibres of the second degree it is mixed homogeneous, in the fibres of the third it is mixed heterogeneous. Phut the fibres aro distinguishod one froin the Other, in the Same manner as the fluids of the fibros in the bratias avd me-
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dullae, and that also in the body they are thus separated, Willbe Seen in Pari III., on the Substances of the Brain; and in Ρart IV., on the Tunics of the Brain; as also in the severat Paris on the Nerves, Muscles, and Glands. What the condition is of vesseis of the second Order, Or thOse Whieli conveythe purer blood, may appear hom the ratio of the fibres as compared With that of the red blood, sor they are the intermediates betWeen the tWO, and DOm tWO gi ven extremes may be educed by analysis the relation Os the meanS. 158. Hence the transition of the blood, membranes and vessela ofone order into those of another, is not effected by continuous attenuation or decrease, but by a division and separation of each unit
divided, and with a membrane thus elevated Or Separated, ascendes out of a loWer into a superior Sphere. 159. For the salie of more clearly understanding the Sub
juct, let the severat sirst entities of any one degree be compared With uniis. A unit os an inferior degree is composed Os aggregate uniis of a Superior degree, but in addition to this there mustbe a third accessory substanee, Which gives it determination, copulates, and perfecis it. In the bl ood this third accessorysubstance is the volatile sali, Whether SulphurΟHS Or urinous; in tho fibros it is tho iunio sileathing the collective fasciclo: consequently, the third substance, adequale to the formor audconnecting it, is either internal or Glernal. Hence a unit thus compounded, belare it loses iis nature Or reascends into tho Sphere of superior uniis, must in like manner be divided,' un-bound, Or Separated; lar instance, the blood must divest itsolsos iis saline corpuscles, and the nerve of iis integuments.160. A unit os a superior degree is compOunded SucceSSively, whenco it follows that it is also resolved successively. For the
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CR ISMeS, Or they never could conformably to them determine effecis; they never could be either in a state os conatus, Or EXCite actuat motion; they never could Will and perform actions in the body, much Iess could they proscribe laWs to Organs and members of in serior rank. In things simultaneous, action is Simultaneous; in things successive, action is distinet and ordinaten, Or Recording to a certain Order. Animal nature is asit Wore ali in iis pure and least principies, nor does it Observe any laws but those of the universo. The puror it is in iis Substanee and Drce, the more universat and persect is it in acting and prospectively providing. The more compotitiden itis, the more particular and limited is it. For Dom iis pure indleast principies it has relation to eve thing; in iis compoundedstate it has a relation to some one thing in particular; it circumscribes itself With ends, very conspicuous and desinite, Wheneuer it compotinus iiself, but it is in relation to the neigh-boring paris that it forms iis limiis, in ordor that hom iis OWnpure principies it may be en led to maintain a relation to every state Os the WhOle compound. For by means of the fibres, whicli are animatest With spirit, it descends to the respective
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homosseneous to a pure volume. For as it proceeiis, it purifestiset froni the serum; so that whide accomptishino iis transitioninto the veins, it becomes a pure volume; the miXed heterogeneous and homosseneous substances belv successively separated and
ejected. Τhis is testified by the excretion of tho urine, theSWeat, the Sanctorian perspiration, and by a variety of otherthings. Asain, in the veins the blood passes from a pure into
a mited homogeneous volume, and Dom a mimed homogenesus inlo a mised heterogeneous volume. For in the fame order in
whieli tho blood is dividen in the samo it is compounded. The Same procera iastes place in the volume of the simpler blood, and the sume again in that of the spirituous suid. To colluci thevari Ous testimontes in support of these severat positions, Would require me to range the selds of natural chemistry, adenology, and pathology. Stili it is necessary to mention and to insertilium in their proper order, With a vieW to preserVe the conue tion botWoen the disserent paris os Our subjeci. As I cannot, hoWevor, falle the wide excursion to Whicli I have adverted, Iam under the necessity, as I Sald besore, Of referring to succeeding ch ters, Where the facts are discussed ni large. Forit is in experimental fucis Mone that ali the strengili os confirmation lius, and of the assistance of these I should be virtu-
bu laid. The mere poWers of genius, unaided by facis, arealtogether uneques to resse the edifice of true philosophy, andis they attempt to bulld it is only upon a basis of air. Theomniscient appears to have plucked the Wings Dom the Mercuries of Our planet, test in disorderly multitudes they shouldroam ut large in the highest regions os Our atmosphere, tili theylost their breath, and diud os distention; and test some should Wish, With the daring of Icarus, to Soar to the precinis of the sun , and to be Scorched With iis rays; that they might vaunt astor their sali hoW very near they had been to a heaven that is foretgn to their nature, and that at the expense of their Wings, thoy had brought down Ρromethean fre, and drank the draught of the superior aura. No Other Wings staturi there re are
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alloWed to the geniuses of the present age than Such RS are
163. As both the blood and the Desseis are os a three ldorderi so also is evem tewture which is formed by the veraeis; assor instance, the olands, which are the receptacles of the secretions, and the ducis of the ercretions; for they are con sun more simple, and most simple: and accordino to the order lo whichthey belono, they are called either gland8, ve8icles, Or porra; One of which is compounded of the other, and one is divided into theother. The divisions and definitions of the glands, as givenby disserent authors, have been someWhat numerous. AS iotheir division, most generalty they are dividest into conglobate and conglomerate. According to Heister, the conglobate are Simple, consisting of One spheroidat corpuscule, distinet, and en-olosod within iis oWn diminutive proper membrane. The COΠ- glomerate, Whicli are alSO called compOund, are, according to Nucli, those Whicli, constituting a congeries of Smaller glands, are enelosed in One common tunic. Each of these glands emits R Smali eXcretory vesset, composing a canal, by Whicli iis liquor 1lows out of it into some observabie cavlty Within the bodn orolse goes Out of the body altogether. They are nothing buta tissue Os most minute vesseis composed of the finest arteries, terminating in tWo Linds of Smali VeSSeis, One Venous, Oradmitting venous blood, and the Other excretory. As to the de sinition of the glands, they are desined by Some as globose, SOR, IRX, Spongy paris, as parenchyma, or as fungous flesti; byOthers, as a congeries of Vesseis enclosed Within their OWn proper membrane; by Others they are called gland8, On account Osthe feshy substance peculiar to them, that is, On account Oftheir peculiar forin, Or their singular externat appenrance. Similar corpuscules, in a preternatural State, are frequently denominated by Alalpighi, diseased tubercles, atheromata, Stentomata, grandines, Ac. And since they noWhere agree either intexture, siluation, Or use, a diSpute has arisen, Whether eVerything is to be called glandular Whicli in any pars of any Viscusor ViSCern represenis a Vaseular and Vesicular congeries and
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cular fissuos as me do the blood and iis vesseis, and is se contemplate their degreus and origins either in a tWO ld Or three sold relation: and is, thus discriminating betWeen their natures, Me give them appropriate names, theu Will the definitions osmost authors agrest, taking them in their broad sense, together With their deduction and description, and the foregoing Various opinions Will be Dund to harmonige in one, as founded uponone and the fame common notion n. 10 . Α gland is a coacervation Os blood-vesseis os a threemld Order, consequently of the arteries and vetus of the red blood, of the purer blood, as also of fibres; and as glands are mutuatly distinguished DOm enchother by their origin and composition, so are they likeWise bytheir appellation. Each congeries respectively is circumscribed by iis OWn common membrane. Interiorly there are formed, according to the complication Or conglobation and conglomeration of the Vesseis,) holloWs, and larger and 8m alter ducis, Whicli receive, convey, drain os bring bach, as Weli as excrete the secreted juice, and thus per rm nil the Stupendous Operatiotis Whicli are found to talie place in the chemistry Os nature. Is the smallest hollows, or those belonging to the sirst ordo be called itimost recesses, Or litile sonis inaccessibie to anyreaul, of the externat senses; and is the litile ducis of that ordor be called by their common appellation os pores, invisibie commissures, litile chiniis rimulae , permeable lines, Or Other-Wise; then a compages of these, overinid With their oKn proper
cumscribed stili further With another common membrane, begeis another Order, WhOSe SomeWhat larger cavities, or litile vesseis receptory of SecretionS, may be called either minute vesicles, orsollicles, Or Duntains, or receivers, or litile cases Os fluid, or by
any other such name; and their litile ducis may be called passages commeatus , or operi inleis Daccessus hiulci , fissures, Or
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the compages Whicli resulis Dom these, namely, a larger glomeration, Or globe, Whether it be of R IOOSe, Spongy, fungous, Orelse of a dense and compaci texture, and Whatever be iis color, fgure, magnitude, appearance, and garb, is neverthel ess in the proper Sense a gland . Iis minor cavities are also properly VeSSeis receptory Os secretiolis, loculi, vesicles, sollicles, celis; iis larger cavities ure receptacles, conduitS, CyStS, Ventres, CiSterΠS, caVernS, fauces ; their ducis are cannis, Siphons, sOSSulae, infundibula, and so forth. The circumstance of their being largeror Sm alter does not alter the nomenclatiare. See n. 156.
Without, hoWever, illustration by examples, We shali ad-vance but floWly. Let iis therofore talle the case of the brain, Whicli in the intricato conglobation of iis simple and primitive Substances is an exemplar and emgy of nil the compositions and derivations to be found in the body, and heuce also the essigyand exemplar os ali the glands. Α spheriale os cortical Or cineri
ble lines proceed, is not a gland excepi in an eminent sense. Thespherules and portiles of this Lind are conglomerated into nuclei, nodes, Or cerebellules, Whicli in the fari troating on that subjectu e shali cali cortical tori, and Which, both in their smalloremgy and in their appearance, altogether resemble the cerebellum, sueti as it is in iis larger essigy; and wheti overtaid withtheir ΟWn proper membrane, comp0Se another degree of cortical spherules, Whicli nevertheless cannot be called glands except byWay Os analogy. From these again, connected together in thesorin of a spiria, and discriminated into Separate conVOlutions, nil overtain and bound together With a doubie or triple tunicor meniux, the brain is produced; and thus has the character ofa great or principat gland, Whose larger cavities are the laterat ventricles, the intermediate ventricte, and the aqueduci; iis pas- Sages are the foramina, called the vulva and the anus; iis excretory is the infundibulum, Whicli in the humati subject is, together Mith the pituitary gland, employed to discriminato the
humors whicli floW into it. Not to mention innumerable otherthings, Whicli most satisfactortly teach us the nature of the gland8. Os these severat degrees of glands, the cerebellum be-
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longs to the second, hecause it is homogeneous to the soconddegree of gland 8, or to the cortical tori of the brain, With whichit corresponds. In like manner the glands, Whicli in the bodyare called conglobate, are in their composition glands of the Second degree; the conglomerate being those of the third de-gree. From the foregoing remariis it noW solioWs, that 165. In a similar order are carried on the secretions from thesmali arteries into the above olaniis; as weli as the cretions: likewise the commimtion of the secretions, and the reabsorption by the Meins. I have a ready been dotained long enough by the consideration Of these more universal topies; let us noW proceedio the bl ood, properly so called, and to iis circulation, Whicli is the main object of the present Ρart. 166. To the end that ali these thinos may attain to their dueesfeci, there is required a constant circulation of the sanguineous Nolume8 ; namely, a circulation of the red blaod from the tot sideos the heari into the trunk of the vorta; from the trunk of theaorta into iis branches; froni iis branches into the smallest vesseis belonying to that order; froni these smallest vesseis into the smalia est veins, as weli as into the numerous hollatos and receptacles forthe secretions. On these subjecis, as no doubi has been entertained, I sorbear mining any comment. This circulation is performed by successive propagations os an undulation, euch σwhich takes place within an imperceptibie moment of timer in consequence whereos there arises in every part of the permeated tessela that sensibie elevation which is denominated the pulse. What that is Which produces the pulse Or causes the salietice Ofthe arte , is a question Whicli has been classed among the
Oeculi secrets of anatomicat science, and the solution of Whichis a desideratum among the learned. Some there are Who attributo it to tho blood only, to iis heat, iis spirit, iis fermentation. Othors who attribute it to the fibros and bratiis. Others Who attributo it to the tunios, particularly the muscular, the extensionos Whicli Galen Was of opinion depended upon a pulsisic faculty. Willis thought it deponded upon the animal spirit. Vietissens solely on the impulse of the blood, Which he considerest to beendoWed With an expansive force n. 122.) There are those again Who attribute it solely to the heari, and maintain that thuarteries have nothing to do With it; While others attribute to
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ille heari and arteries equat shares in iis production. Whateverbo the cause Or causes of the phenomenon, there has I thinlibeen no disputo that the effect produced is an elevation and throbbing of the artery, as perceived upon applying the finger. Vieusseris snys : It is very evident that in that motion of the arteries Whicli is properly called dilatation, their conis urestretched in overy direction beyOnd their natural degree os tensionV n. 122 . LeeuWenhoeli states that this arteriai tensionis carried On even in the very minutest arteries; for that he
and has iis termination ut the extreme ends of the smallest Vesseis, Where it is continued into the minute vetus, is a factwhicli admits of litile controversy; for, as We have Sald, thOSe protrusions have been actualty seen, as also the smali volumes and paris of the blood Whicli urere hurrien to and Do; the increased rate of speed occasioned by the extension Os the vesset ; the informissions Which took place Whenever there WaS nny intermission in the motion of the heari; the states of inactionand quiescence Whicli solioWed When the motions of the heari censed; the successive and distinet translation of the volumesrom the venous sinuses into the auricles, and thetice into the ventricies of the heari, Whicli are succeeded by the arteries, these converting What is successively contiguous into What is succes-SiVely continuous. Reason also is On the fame fide of the question; λr Were the elevation Os the artery instantaneous OrSimultaneous, the artery Would repress the blood ns much as it