m «r hO tm iV-'VfcJfd* m ms ■" --■*-•• '-•'. Ml ■.■-■' • ■ ■- B ■ ■•■'■. N^MNftftJE im m HI Ymf hB^HMmbh • Bfli '*-':«' ^ k ru ru \ o LU ■ 00 1 if t (y 3 X ZOONOMIAi OR) THE LAWS OF ORGANIC LIFE IN THREfe PARTS. By ERASMUS DARWIN, M.D.RR.S, AUTHOR OF THE BOTANIC GARDEN, PHYTOLOGIA, &C Principid cceium, ac terras, campofque liquentes, Lucentemque globum lunse, titaniaque aftra, Spiritus intus alit, totamque infufa per artus Mens agitat molem, et magno fe corpore mifcet. Virg. JEtt. VL Earth, on whofe lap a thoufand nations tread* And Ocean, brooding his prolific bed, Night's changeful orb, blue pole, and filvery zonesj Where other worlds encircle other funs* One mind inhabits, one difFufive Soul Wields the large limbs, and mingles with the whole. COMPLETE IN TWO VOLUMES. irrnMMti " Vol. I. Second American, from the third London Edition, corrected by the Author. Printed at Bofton, by 15. Carlisle^ For THOMAS and ANDREWS. Sold at their Bookftore, No. 45, Newbury Street; by I. Thomas, Worceftcr ; an<£ by Thomas & Thomas, Walpole, N. H.— Sold alfo by T. Sf J. Swords, . New York ; Whiting, Leavenworth G? Whiting, Albany; O, Penniman & Co. Troy ; and Thomas, AK* drews Sf Butler, Baltimore. Feb. 1803, DEDICATION. .* i To the candid and ingenious Members of the College of Phyficians, of the Royal Philofophical Society, of the Two Uni- verfities, and to all thofe, who ftudy the Operations of the Mind as a Science, or who praftife Medicine as a Profeffion, the fubfequent Work is, with great ref- pe6l, infcribed by the Author. Derby, May i3 1794. • *<^^ T O ERASMUS DARWIN, ON WIS WORK ENTITLED, Z O O N O M I A. By DEWHURST BILSBQRROW, ii tuiii.i»!imMM»jiiM».i?wi— s—^wiu mm n Hail to the Barb ! who fung, from Chaos huiT4 How funs and planets form'd the whirling world j How fpherc on fphere Earth's hidden ftrata bend, And caves of rock her central fires defend ; Where gems new-born their twinkling eyes unfold, I And young ores fhoot in arborefcent gold. How the fair Flower, by Zephyr woo'd, unfurls Its panting leaves, and waves its azure curls ; Or fpreads in gay undrefs its lucid form To meet the fun, and ihuts it to the ftorm ; je> While in green veins impaflion'd eddies move, And Beauty kindles into life and love. How the firft embryon fibre, fphere, or cube, Lives in new forms,— a line,— *a ring, — a tube ; Clofed in the womb with limbs unfinilh'4 laves, jj Sips with rude mouth the falutary waves ; Seeks round its cell the fanguine ftreams, that pafs, And drinks with crimfon gills the vital gas ; Weaves with foft threads the blue meandering vein, The heart's red concave, and the filver brain ; %f> Leads the long nerve, expands the impatient fenfe, And clothes in filken {kin the nafcent Ens, Erewhile, emerging from its liquid bed, It lifts in gelid air its nodding head ; The light's firft dawn with trembling eyelid hails, $J With lungs untaught arrefts the balmy gales ; Tries its new tongue in tones unknown, and hears The ftrange vibrations with unpractiied ears 5 Seeks with fpread hands the bofom'o velvet orbs, With clofing lips the milky fount abforba 3 And, as comprefs'd the dulcet ftreams diftil, Prinks warmth and fragrance from the living rill }<*■ I Vi TO ERASMUS DARWIN. Eyes with mute rapture every waving line, Prints with adoring kifs the Paphian fhrine, And learns ere long, the perfecl form confefs'd, Ideal Beauty from its mother's breaft. Now in ftrong lines, with bolder tints defign'd, You fketch ideas, and portray the mind ; Teach how fine atoms of impinging light To ceafelefs change the vifual fenfe excite : While the bright lens coiled s the rays, that fwcrve, . And bends their focus on the moving nerve. How thoughts to thoughts are link'd with viewlefs chains, Tribes leading tribes, and trains purfuing trains ; With fhadowy trident how Volition guides, Surge after furge, his intellectual tides ; Or, Queen of Sleep, Imagination roves With frantic Sorrows, or delirious Loves. Go on, O Friend ! explore with eagle-eye; Where wrapp'd in night retiring Caufes lie : Trace their ilight bands, their fecret haunts betray, And give new wonders to the beam of day ; Till, link by link with ftep afpiring trod, You climb from Nature to the throne of God* So faw the Patriarch with admiring eyes From earth to heaven a golden ladder rife ; Involv'd in clouds the myftic fcale afcends, And brutes and angels crowd the diftant ends. Trin, Col. Cambridge, Jan. i, 1794. 35 4» 45 50 55 REFERENCES. hoiamc Garden, Part I. Line 1. Canto I. 1. 105. IV. Line 18. Seel. XVI. 2. and XXXVUL 3- 4- 5- 8. 9- iz. *3- I. III. IV I. 1. 40Z. 1. 140. 1. 401. 1. 45*. 1 14. Z&onomia. Sed. XIII. XXXIX.4. I. a6. SO- 36. •38. •43- 44. 45. 47. 50. 5i- 54, - XVI. 4. . XVI. 4. . XVI. 6. - III. and VH. - X. ■ XVIII. 17. XVII. 3. 7. XVIII. 8. XXXIX.4- 8. XXXIX- the MotU. XXXIX. &. PREFACE. 1 HE purport of the following pages is an endeavour to reduce the fa&s belonging to Animal Life into claffes, orders, genera, and fpecies ; and, by comparing them with each other, to unravel the theory of difeafes. It happened, perhaps unfortunately for the inquirers in- to the knowledge of difeafes, that other fciences had re- ceived improvement previous to their own ; whence, in- ftead of comparing the properties belonging to animated nature with each other, they, idly ingenious, bufied them- felves in attempting to explain the laws of life by thofe of mechanifm and chemiftry ; they confidered the body as an hydraulic machine, and the fluids as pafling through a feries of chemical changes, forgetting that animation was its eflential chara&eriftic. The great Creator of all things has infinitely diver- fified the works of his hands, but has at the fame time (lamped Viii PREFACE. (lamped a certain fimilitude on the features of nature* that demonftrates to us, that the whole is one family of one parent. On this fimilitude is founded all rational analogy ; which, fo long as it is concerned in compar* tng the eflfential properties of bodies, leads us to many and important difcoveries ; but when with licentious ac- tivity it links together objects, otherwife difcordant, by fome fanciful fimilitude ; it may indeed collect orna° lnents for wit and poetry, but philofophy and truth re«< coil from its combinations. The want of a theory, deduced from fuch ftrict anal- ogy, to conduct the practice of medicine j is lamented by its profeffors ; for, -as a great number of unconnected facts are difficult to be acquired, and to be reafoned from, the art of medicine is in many inftances lefs efficacious under the direction of its wifeft practitioners ; and by that bufy crowd, who either boldly wade in darknefs, or are led into endlefs error by the glare of falfe theory, it is daily practifed to the deftruction of thoufands ; add to this the unceafing injury which accrues to the public by the perpetual advertifements of pretended noflrums ; the minds of the indolent become fuperftitioufly fearful of difeafes, which they do not labour under ; and thus become the daily prey of fome crafty empyric. A theory founded upon nature, that mould bind to- gether the fcattered facts of medical knowledge, and con. verge into one point of view the laws of organic life, would thus on many accounts contribute to the intereft of focietv. Tt would caoacirate men of moderate abili- tJ< PREFACE. is ties to pra&ife the art of healing with real advantage to the public ; it would enable every one of literary ac* quirements to diftinguifh the genuine difcipies of medi- cine from thofe of boaflful effrontery, or of wily addrefs $ and would teach mankind in fome important fituations the knowledge of themfehes. There arefomemodernpra&itioners,whodeclaimagamft medical theory m general, not confidering that to think is to theorize 5 and that no one can direct a method of cure to a perfon labouring under difeafe without think- ing, that is, without theorizing ; and happy therefore is the patient, whofe phyfician poffefTes the bed theory* The words idea, perception, fenfation, recollection, fuggeftion, and alfociation, are each of them ufed in this treatife in a more limited fenfe than in the writers of met- aphyfic. The author was in doubt, whether he mould rather have fubflituted new words inftead of them j but was at length of opinion, that new definitions of words already in ufe would be lefs burthenfome to the memory of the reader. A great part of this work has lain by the writer above twenty years, as fome of his friends can teftify : he had hoped by frequent revifion to have made it more worthy the acceptance of the public ; this however his other perpetual occupations have in part prevented, and may continue to prevent, as long as he may be capable of re- vifmg it \ he therefore begs of the candid reader to ac- cept of it in its preferit date, and to excufe any in- vol. *• h accuracies x PREFACE. accuracies of expreffion, or of conclufion, into which the intricacy of his fubjecl, the general imperfection of language, or the frailty he has in common with other men, may have betrayed him ; and from which he has not the vanity to believe this treatife to be exempt. PREFACE PREFACE T O THE THIRD LONDON EDITION. 1 HE Reader fiiould be apprized, that many new pages are interfperfed in this edition, which confift of practical and theoretical obfervations, as the whole articles on He- micrania idiopathica, retroverfio uteri, aneurifma, and the appendix to the fection on Generation, beginning at No. 8. as well as the diftin&ion between philofophy and fophiftry in Seel: XV. i. 5. and the Ratiocinatio verbofa, verbal reafoning, in Clafs III. 2. 2. 3. and fome others. Derby, Jan. 1, 1801. o3" In the former editions of this work the Materia Medica [which forms Part III.] was placed after the fecond part, or the clafles of difeafes, but to preferve the more equal fize of the volumes, in this octavo edition, the publifher has placed it, with the aflent of the author, af- ter the firft part. CONTENTS. CONTENTS, PART I, Page, Sect. I. Of Motion. ------ i II. Explanations and Definitions. 3 III. The Motions of the Retina demonftrated by Experiments. • * 8 IV. Laws of Animal Caufation. 20 V, Of the four Faculties or Motions of the Sen- forium. - - - - - -21 VI. Of the four Gaffes of Fibrous Motions. - 23 VII. Of Irritative Motions, 25 VIII. Of Senfitive Motions. - - - - 29 IX. Of Voluntary Motions. "V '"' - - - 31 X. Of Affociate Motions. 34 XI. Additional Obfervations on the Senforial Powers. ----- 37 XII. Of Stimulus, Senforial Exertion, and Fibrous Contraction. - 43 JQII. Of Vegetable Animation. 73 XIV. Of the Production of Ideas. - - - 79 XV. Of the Gaffes of Ideas. 95 XVI. Oflnftina. - - - - - 1 oi XVII. The Catenation of Animal Motions, - 143 XVIII. Of Sleep. - - - - - ~T53 XIX. Of Reverie, » - - • - 170 XX. Of Vertigo. - - • - - 175 XXI. Of Drunkennefs. - - - - 10 \ XXII. Of Propenfity to Motion.- Repetition. Im- itation. ------ ip8 XXIII. Of the Circulatory Syftem. - - 206 XXIV. Of the Secretion of Saliva, and of Tears. And of the Lachrymal Sack. - - 212 XXV. Of the Stomach and Interlines. - - 217 XXVI. Of the Capillary Glands, and of the Mem- branes. ----- 226 XXVII. Of Haemorrhages. - 229 XXVIII. The Paralyfis of the Lacteal*, - - 234 Sect, xiv CONTENTS. Page. Sect. XXIX. The Retrograde motions of the abforbent Veflels. - - - - - 238 XXX. The Paralyfis of the Liver and Kidneys. - 272 XXXI. Of Temperaments. - 277 XXXII. Difeafes of Irritation. - 282 XXXIII. of Senfation. - 305 XXXIV. of Volition. - - - - 324 XXXV. — of AfTociation. - - 343 . XXXVI. The Periods of Difeafes. - - 352 XXXVII. Of Digeftion, Secretion, Nutrition. - 360 XXXVIII. Of the Oxygenation of the Blood in the Lungs and Placenta. - - - 366 XXXIX. Of Generation. - - - - 373 XL, Of Ocular Spectra. - 443 [Part II. forms the second Volume.] PART III. articles of the materia medica. Art. I. Nutrentia. II. Incitantia. HI. Secernentia. IV. Sorbentia. V. Invertentia. VI. Revertentia. VII. Toroentia. Page. 5 l9 3* 42 65 7° 73 INTRODUCTION INTRODUCTION TO THE AMERICAN EDITION CONTENTS OF THE INTRODUCTION, ObjeB of thejirjl part of the Zoonomla. Arrangement of living motions* Functions referable to each of thefe. Clarification of animated adioti under four heads. Influence of Jlimuli in fuflaining life. Comparlfon of Dr. Darwin's doitlrlne of Jllmidus and exertion with the Brunonian Elements. Great refemblance acknowledged by the former. Which of them was indebted to the other ? The two authors efpoufe Jimilar funda- mental principles. Examination of the Jlander that Brown's dotlrinc was but a revival of the opinions of the ancient Methodic Seel. HIJIg- ry of that feci. A branch of the Epicureans. Sketch of the Epicurean, philofophy. Application of this to medicine. Reafoning wholly mechan- ical. Hiflory of the opinions concerning life fuperadded to mechanifmy from Hippocrates to Cullen. How far the latter had proceeded. Mer- its of Brown. Abflrabl ofthefirjl edition of his Elementa, publijhed in 1780, and now very rare. Review of his fecond edition in 1784. The Englifb work a mere tranflation of this. Epitome of the Bruno- nian Dotlrine. Very different from the notions of Themifon and Thef- falus. Defecls in Brown's fyjlem. Room for improvements. Great amendments made by various perfons. Introdutlion of chemical princi- ples and modes of reafoning. Infujficient to explain the phenomena of life. Laudable attempt of Dr. Darwin to invejllgate thofe laws which neither mechanifm nor chemiflry can explain. Objetl of the fecond part to form a nofology, or catalogue of dlfeafes, by a natural clajJiflc%tionf founded on their proximate caufes. AN attempt has been made in the firft part of this work to in- vefligate the complex laws of animal caufation. Thefe are de- duced from the contractions and relaxations performed by the living fibres, which conftitute tht mufcles and organs of fenfe. Fibrous con- tractions feem to conftitute all the functions of animated bodies, *ad indeed all we know both phifiologically and medically con- cerning *vi INTRODUCTION TO THE terning life and its functions. They are arranged into four clafT- es of motions, which form the foundation of all juft nofology and practice, as detailed in the fecond great divifion of the Zoonomia. Vi- tal motions are thus called irritative, fenjhive, Voluntary, and ajfociated, according as the parts of the body in which they exifl are endowed with irritability, fenfalion, volition, or fympathy. This quadruple allot- ment of functions forms a llrong and peculiar character of the follow- ing work. And the diftribution of the almoit endlefs variety of ani- mated phenomena into this fourfold and lucid arrangement, is a clear proof of the discriminating and generalizing mind of the author. But in all thefe conditions of the fyitem, whether influenced by the vis infita or the vis nervea, by voluntary or fympathetic energy, the fen- forial powers are fuilained by the unceaiing operation of stimulants. The theory of thefe is contained in the twelfth chapter of the firft part, and exhibits very advantageoufly the doctrine of (limulus, and exert iont or as it has been more generally called, excitement. There is a itriking analogy between thefe fundamental doctrines of Dr. Darwin and thofe contained in Dr. Browns Elements of Medicine. Our author was aware of this, and to guard himfelf againft the impu- tation of having borrowed Brown's ideas without acknowledgment, or of being merely his imitator, he obferves that " the coincidence of " fome parts of this work with correspondent deductions in the Bru- " nonian Elementa Medicince, a Work (with fome exceptions) of great " genius, muft be confidered as confirmations of the truth of the " theory, as they were probably arrived at by different trains of rea* " forting." In vefpect to Originality, there is great difficulty in fettling claims* In this cafe however, there is not even a fufoicion that Brown derived any thing from Darwin. Both might indeed have come to fimilar conclufions, by the independent exercife of their reafon, without any communication or inlercourfe. And yet, an impartial obfervcr, prone neither to obloquy nor flattery, would not forfeit his candour in fuf- pecting that a writer of Darwin's acutenefs might have gathered fome- tiling from Brown, who- publiflied fourteen years before him. Confidering the Brunonian and Darwinian fyftems as retting upon the fame pillars, it appears to me there may be both uSeSuhieSs and cu- riofity in Searching and digging about the ground on which they (land. In performing this talk, it has been expected there mould be a ftate- ment /hewing how far thefe doctrines of the Scottifh and Englifh phy~ fieians are themfelves novel or modern, or whether they are both of the old School and derived from remote and ancient Sources. By deciding in favour of their modernity, it will be likewife expect- ed that a view fliould be given of the Brunonian fyftem, thai it may be compared with the cotemporary doctrines of Cullen and Darwin. Jn this comparifon, it will be found, that Brown's merit is very con- fpicuouS. The three diftinguifhed authors have fmifhed their earthly id they and their writings may now be confidered without iality. To thofe who are curious to trace the progrefs ♦f thefe opi nil -Inch exert Such extenfive dominion over the mind* thefe AMERICAN EDITION. xvii thefe introductory remarks may perhaps afford fome gratification. Others, who poflefs not the tafte or leifure for fiich enquiries, may pafs them over, and in the progrefs of obfervation and experiment in phyfics, within a few years, fuch a number of new and important facts have been brought to light, that many philofophers have believed the peo- ple of the prefent day were pofTeffed of a great deal more knowledge than the moderns of the three laft centuries, or their ancient prede- cefTors. This opinion, in particular, has been deemed well founded, and true in its refpect to medicine, which, at this time, is not only confidered fufceptible of new expofitions and interpretations, but of being great" ly improved and enlarged, both in theory and practice. And although among thofe who think thus are reckoned molt of the original and clear lighted geniufes of our time, yet there are not wanting fome, and thofe men of talents and reputation too, who are in the habit of thinking, if the ancitnts knew not quite as much as ourfelves, yet their writings contain the leading hints, or great outlines of almoil every thing dif- coverable, either directly expreffed, or fignified in allegorical terms. This literary fuperftititon has been carried a great way ; and if it had Hopped at declaring the Iliad the beft of pofiible poems, or the PhlU liplcs the moll finifhed of the rhetorical productious, I mould not at this time have troubled myfelf to contradict it. But when thefe euthufiaftic admirers of antiquity declare, that, in matters of fcience as well as of letters, the fubjects of enquiry have been exhaufted two thoufand years ago, and that no idea can be ftarted which is not an imitation of fomething that a Greek or a Roman, or fome body elfe, had thought before, I own 1 am a little difpofed to believe their aiTertions are grounded neither in truth nor in the nature of things. For why muft we refort to the Platonists, Stoics, and Peripa- tetics, for doctrines which the Academy, the Porch, and the Ly- ceum never knew ? Thefe remarks are made in confequence of an opinion propagated and believed by fome, that a certain method of reafoning upon medical fubjects, and of medical practice introduced now of late as many be-, lieve, which are already pretty well eftablifhed, and acquiring rapidly more and more adherents, are in fact but a revival and new modelling of the opinions and procedure of the Methodic Sect, founded by Asclepiades, the cotemporary of Mithridates and Crassus. ' In order to know whether this opinion -is well founded, 1 mall en- quire what the philofophy of the Methodic Sect was. Its founder, Asclepiades, adopted that philofophy, whofe foun- i dation had been laid by Anaxagoras, Emfedo-cles, and Heracli- tus, and which was afterwards wrought up into the Atomic Syflem, by Leucippus, and Democritus, of the Eleatic Seel ; who, rejecting all mctaphyfical explanations of the caufes of things, undertook the inter- preting nature, from the laws of matter and motion. This was after- wards commented upon, enlarged and adorned by Epicurus, fo as to form, what was afterwards called the Epicurean Philofophy . What the details of this are, may be feen in Diogenes L,A£RTius,in Vol. I. c Bku'cks-r < xriii INTRODUCTION TO THE Erucker and his tranflator Enfield, as well as in the poem of Lu- cretius, who has confeffedly attempted a poetical difplay of thefe very doctrines. A general view, comprrfing a mere fketch of the fyf- tem of this /YyJe5$«f*7os or felf-taught man, as he called himfelf as far as connected with the prefent fubject, is all I fliall offer here. An Epicurean would explain himfelf thus : — " It is clear, from the chang- " es which natural bodies undergo, that there is a perpetual formation " and dedruction of them going on ; there muft then exift matter of ' which thefe things are formed, and into which they are refolved ; and hence proceeds the conclulion which is the ground-work of the " fyftem, that a thing car. neither be made out of nothing, nor reduced M to nothing. " Nullum rem e nihil o gigni divinitus unquam." The " univerfe, therefore, as to its conltituent atoms or particles, was al- " ways as it is at prefent ; and confequently matter is eternal. The " workman cannot perform any thing without materials ; and thefe 11 felf-exiftent materials, in the decay and renovation they undergo, ac- " count for the phenomena of nature and of art. If things were cre- " ated out of nothing, then every kind mould proceed from each, and " the greateft irregularity enfue ; men mould be produced in the fea, " fifties on the land, and cattle in the clouds ; generation would be ufe- " lefs. and food unnecefTary : if they returned to nothing, then, in the " courfe of pail ages, through wafte, confumption, and lofs, much " muft have vanifhed to non-exiftence, and have been completely anni- M hilated. But neither of thefe fuppofitions is true, fmce out of the " wreck or ruin of one being or exiitence, nature, we know, without an " aft of creation or annihilation, can work up the old materials into a " new fabric. " All exigences in nature are referable to two kinds, I. Bodies ; 11 and, 2. The inane , or void in which they exift. " Our fenfes fatisfy us of the exiitence of bodies, as alfo do their " actions, paffions, and refilling powers ; particularly as they operate *l upon each other, and upon our touch : " Tangcre cnim et tangi nifi corpus nulla poteft res." — Luc ret. ■ For nothing but a body can touch or be touched." " From the exiitence and motion of bodies is inferred the exiftence " of fpace ; and the effect: of bodies operating upon each other is de- " nominated " an event ;" and if there was not a void there would not «' be a poffibility of motion ; for if a plenum exifted, then every portioa " of fpace being clofely impacted and wedged with folidity, the molt " uniform reft and dead ftilinefs would pervade the whole of nature. " As to bodies, they cither confift of elementary atoms, or of fub- '• lances formed from thefe ; and thefe primordial particles, notwith- " (Landing fome appearance:, to the contrary, are fimple, folid, and 4i indivisible. " Sunt igitur solida, ac fine inani corpora prima." — Lucrkt. '■ Therefore Llenicntary bodies are folid and deftitute of vacuity." a All AMERICAN EDITION. xix " All thefe atoms poffefs the fame general properties, and do not " differ from each other in any effential refpeft. Though, from their « different operations upon the fenfes, is inferred a difference among « them as to fize, fhape, and heavinefs. Their figures, in particlur, « are varied in an endlefs manner, fo as to take on every mechanical " form : but in all thefe cafes they are {till infrangible and incapable " of farther divifion. « Each atom contains, within itfeif, an active energy, or internal ** force, by which it is either conftantly in motion, or making an effort " to move ; and this is denominated gravity. Thefe atoms, impelled " by gravity through void [pace in curvilinear courfes, ftnke againft " each other, exercife repelling powers, and produce vibration or agi- " tation ; and as this gravitating power is effential to matter, it can « never be ina&ive, but muff be always at work, and has been fo from V eternity. " Every compound body, being made up of individual atoms, there. " fore potfeffes the united energy of them all, which energy is the Jole "-agent in nature ; but by reafon of their different figures, their " varied magnitudes, and particular fituations, it is varioufly modifi- " ed ; as when the atoms are hooked or rough, motion will be retarded " among them, and be facilitated when they are round and fmooth, as " in the principles of fire and animation. Bodies thus being compof- " ed of atoms, derive their actions from the energy inherent in and " proceeding from thefe atoms. " All alterations happening in bodies, whether in their fhape, hard- " nefs, fweetnefs, &c. are afcribable to the change taking place in the " arrangement, difpofition, Sec. of the conftituent particles ; and thus " porolity, tranfparency, elafticity, malleability, &c. are to be account- " ed for in the fame way. Gravity being an effential property of mat- " ter, all corpufcules, and all bodies formed of them, muff be heavy. " Thus, from thefe properties of bodies, their feveral combinations " and mechanical operations, arife other more complex phenomena, ** referable however to the principle of motion, fuch as the heating of " bodies from the influx of foft, round and fmooth particles ; the cool- ic ing of them from the ingrefs of atoms of oppofite and irregular " figures ; even fenfations, both of the pleafurable and painful kinds, " motion, reft, and time itfeif, are contingences to bodies. In fhort, " the whole phenomena of the production, growth, nutrition, decline, " and diffolution of bodies, is to be afcribed to an alteration of ar- «' rangement in the particles, and to their addition or fubtra&ion. " Minerals, plants, and animals were thus produced in the beginning, " according to thefe mechanical laws of matter and motion, and fo was «* the world they compofe and inhabit. They continue to propagate " their kinds in regular ways,becaufe nature has become accuflomed,by " babiti to produce them in an order fo uniform as to look like defign. " The eye, however, was not made for feeing, nor the ear for hearing ; " but having been accidentally formed in fuch a way as to aniwer " thefe psrpofesj this fentient principle within, which is co-sxiflent " with *x INTRODUCTION TO THE " with the organization, finding them fit for the purpofes of fight and " hearing, makes ufe of them accordingly. " Seniation, proceeding from the arrangement and texture of parti - " cles, is to be afcribed to their peculiar magnitude, fhape, combina- f* tion, &c. fo that inilead of being an original property of matter, it tf is, in fact, only an occafional quality. Death is the privation of ei fenfation, in confequence of the feparation of the fentient principle " from the body : and this fentient principle, when a man dies, is de- " compounded into its fimple atoms, lofes its fenfitive powers, and goes *' into other forms and combinations. The foul, in this refpect, re- §* fembliug the eye, which is no longer capable of performing its func- (i tions than the connection of its organized texture with the body lafts." What Asclepiades did, was to apply the principles of the Epi- curean Philofophy to medicine, and this he did with much ingenuity and acutenefs. Building upon that hypothefis, he fuppofed the hu- man body compofed of Epicurus' ultimate atoms, which, by their figure, proximity, and arrangement, enabled it to perform its functions ; and in a particular manner, that health confided in the fymmetry and permeability of certain pafiages through the firm parts, which he call- ed pores ; and the clofing up, or obftruction of thefe, conftituted dif- cafe. He imagined the fluids to be formed of particles, varying in figure and fize, and thus making all the varieties of them, from the trucked blood to the moil attenuated animal fpirits. And when thefe fluids moved freely through their pores, the body was found ; but when they were too narrow, fo as to produce ftagnations, or fo oblique as not to be readily pafTable, then indifpofition enfued. Such were the leading principles of Asclepiades, and he had ma- ny followers, among whom Themison of Laodicea was the moil eminent. He rejected molt of the fubtle and laboured reafonings of . mailer, and, declaring fuch minute inveftigations were ufelefs, af- firmed, without delcending to particulars, and burthening himfelf with tails, a phyfician need only make himfelf acquainted with the gen- eral principles of difcafes. Thefe, he faid, all belonged to two ciaffes. I. Thofc proceeding from laxity; and, 2. Such as were caufed by firiciurc. All that was neceffary to be done, therefore, was to afcer- t.ain to which clafs any given difeafe belonged ; and then, if to the former, to prefciibe ajlringent ; if to the latter, relaxing remedies. The regular and fyftematic plan which Themison and his numer- ous followers adopted in their practice, differing very widely from the conjectural and uncertain mode of other phyficians, caufed them to be called Methodists ; and thev are to this day known in hiftory by the name of the Methodic Sect. While Themison was reflecting upon his fyftem, and endeavouring to advance it to maturity, he died, I the unSniihed work was taken up and completed by his follower Thessalus. He lived in the time of Nero ; and having rejected, olous, all the opinions of his predeceffors, he declaimed, with icmence and fury, againft the phyficians of all ages, and offered to .rucl a beginner in the art of medicine in the fhort duration of fix months. And then, with a degree of arrogance and impudence, of which, AMERICAN EDITION. xxi which, as no parallel is known to have exiiled in ancient times, it can only be found in the hiftory of modern quackery, he took upon him- felf the appellation of ldl$Hx%hg9 or the conqueror of phyficians. After Th ess alus the feci began to decline and dwindle, and al- though Soranus, Julian, and Moschion retarded for a while its downfall, yet it was totally abforbed and loft in the Galenic Doclrines which followed. Thus, from an examination of the Methodic Syjlem, it is evident the explanation of every thing in the animal economy is attempted upon PRINCIPLES OF MECHANISM only. The firft notice- of any thing elfe requifite to give life, arid regulate its functions, feems to have occurred to Hippocrates, the cotempo- rary of Democritus and Leucippus. The to tvooftw of this faga- cious obferver, as the interpretation of the word imports, obvioufly means an exciting power in animals : and the effects of animation re- fulting from this, imperfectly known, and badly explained, doubtlefs give rife, according to the opinion and judgment of the different wri- ters, to the Nature of Sydenham,* the Aura Vitalis of Van Hel- mont,-]- the Vis nature Medicatrix of Gaubius,^: the Anima Medica of Stahl and Nichols, $ and the learned and curious treatife, enti- tled Impetum Faciens, of Kaauw Boerhaave.jj And here it is worthy of remark, that from Hippocrates to Brown, all writers entertain the opinion of a principle or power with- in, exifting as the caufe of life, as appears by the active fignification of all their terms ; whereas the 'idea of the Bruuonians is, that the or- ganized animal folid poffeffes no internal energy, and would always re- main inactive, unlefs excited by ftimuli from without ; they therefore fpeak of the vital capacity in the paj/tve voice, as only fufceptible «f being acted upon. Herman Boerhaave, in his account of the difeafes of a lax and of a rigid fibre, feems a grain to relapfe into the mechanical confideration of thele things ; but Haller, by his numerous and luminous experi- ments on fenfibility and irritability, led the way to a right mode of purfuing and underftanding fuch enquiries. The attention of Hoffman had been turned to the confideration of the nervous fyftem, as influencing difeafes, more particular than any other perfon ; and from his writings were probably taken the hints which terminated in Cullen's doctrine of Excitement and Collnpfe, in his Phyiiological Tract ;^[ enlarged afterwards, and applied to prac- tice, * Opera Paffim. _ f Equidem fciant Spiritum effe aliquem illud impevum faciens Hippocrates, vitc-e clavum manu fua tenens (Ort. Medicin. p. 724.) \ Who quotes Hippocrates for the idea (Sect. 649.) couched under the term of avlonpxlcta. \ Animam effe Guberna»ricem, &c. &c. Oratio de anima Medica. paffim. |j Lug. Batav. Luchtmans, 1745. (Chap. 7.) f Inftitutes of Medicine, \ 126 to 135. " From what has been now faid of the excitement and collapfe of the brain, it will appear that we fuppofe life, as far as it is corporeal, to confift in the excitement of the nervous fyftem, and efpecially of the brain, which unites the different parts, and forms them into a whole.'1 <- 136. INTRODUCTION TO THE ticc, in his chapter on vefanias, (Firfl Lines, § 1544. and feq.) as well as the obfervations in his letter on the recovery of perfons drown- ed : (p. 4.) " Though the circulation of the blood is neceffary to the fupport of life, the living (late of animals does not confift in that alone, but efpecially depends upon a certain condition of the nerves and mufcular fibres, by which they are fenlible and irritable, and upon which the action of the heart itfeif depends," &c. And alfo the re- marks on the effect of ftirnuli in keeping up the action and energy of the brain* at all times, in his treatife upon the materia medica. John Hunter had been fpeculating too on this fubject. In his experiments on animals, with refpect to their power of producing heat, he has brought curious and important facts to view : though his reafoning on them is in fome inftances inconclufive and exceptiona- ble, in others quite unplulofophical. This enquiry was intended as a counterpart to the experiments of Blagden, and his affociates in the heaied chamber, on the power of the human body to produce cold in high temperatures. He afcribes a great deal, throughout his per- formance, to the ftimulant action of cold, and to the exhauflion of the whole of the powers of life in freezing animals, by their efforts to produce heat ; he even afcribes the attempt of his poor victim, the dormoufe, to get out of the veffel in which he was to be frozen to death, to the roufing of animal aBion by cold 1 He feems to take little notice of the vital organs, the fire-place whence the constitution re- ceives its warmth ; nor regard much the condition of the refpiratory function in any of the creatures he operated upon, nor the pain they endured, and the changes in their economy confequent upon it. The experiments on the eggy frog, eel and fnail, may be as well explained on the idea of the increafed fnfceptibility of imprefiion, produced by the fubduction of ftirnuli, and by an extraordinary exertion of the refpiratory organs caufing a greater evolution of heat, as upon the author's hypothefis, which may be fummoned up in this general con- clufion ; that cold produces its effect in fufpending the voluntary ac- tions, by acting as a fedative to a certain point ; beyond which it feems to act as a. Jli mutant, exciting the animal powers to exert them- felves for felf-prelervation. It will be evident to him who reflects on what has been related,1 that the Epicurean Sectaries entertained no other than mechanical notions concerning the production, actions, and changes of bodies ; and that Hippocrates and his followers, though coniiderably more advanced towards the truth, had gone no farther than to obferve foli- tary and individual facts, arrange thefe into detached fentences, or in- flated aphoriftns, fomctimes intirely true, and fome containing only a mixture of truth ; or frame (trange and whimiical hypothefes, by aid of which, as general principles, they attempted to explain things ; and the molt forward of them feems to have done little more than trace the corporeal functions, by partial induction, to the octeiov raPohix-vo or common sensory. Such was the condition of medical fcience, until almofl twenty-five years * Materia Medic?, p. 6", &c. AMERICAN EDITION. xxiii years ago, when, in that very place where fpafmy reaSton, and vis med- icatrix natura were flourifhing in full vigour, under the afiiduous culti- vation of Cullen, they were nipped and cropped in the bloflbm, and nearly eradicated as noxious, by the improving hand of Brown. From the intimate acquaintance which Brown, or Bruno, as he called himfelf, had with the publifhed writings, and probably with the private opinions of Cullen ; from his academic habits, his erudition and knowledge of every thing palling at the Univerfity of Edinburgh, he mull have had great opportunities, as well of learning all that was printed in phyfic, as of Undying the defects, and detecting the weak- nefs of that profeffor's do&rines. He told the writer of this preface, that he ventured one day to talk to Cullen on the incomprehenfible ideas of atony and fpafm exifting in the fame veflels of the body at the fame time ; and thereby provoked him to manifeft ligns of impa- tience and difpleafure. A coolnefs took place immediately, which increafed at laft, by fucceffive and mutual aggravations, to rooted averfion and deep oppofition. And to this irritated (late of Brown's mind, indignant with the fenfe of unbecoming treatment, is to be af- cribed no fmall portion of that rcfolution and energy with which he laboured out a Syftem of Medical Philofophy, which, though not free from errors, borrows, however, none from Cullen. On the publication and contents of the firfc edition of the Elementa Medicinae of this author I fhall be a little particular, an account of the fcarcity of the work, and of the gratification it may afford to an enquiring mind to learn the progrefs of ufeful difcoveries. It was publifhed in 1780, and was dedicated to Sir John Elliot ; but this dedication was withheld from the fecond edition. After {rating his twenty years labour in learning and teaching phyfic, he obferves, it was not until the fourth luftrum that fome dawning of light broke in upon him. The opinion that in the phlegmafice of nofologifts, local affection was not the caufe of pyrexia, but, on the contrary, a fymptom confe- quent upon a previous general excitement of the whole conftitution, appears to have been early adopted by him ; and from his own perfon- al fufferings in eryfipelas, cynanche tonfiilaris, catarrh, and fynocha, and from his perufal of whatever had been written by Morgagni, Trill er, and other candid authors on thefe fubjects, and on pneu- monia, he was confident his idea was right. He, at this time, propofed the doctrine of cold predifpoflng the body to be operated upon in a powerful manner, and to a morbid de- gree, by fubfequent heat ; which, indeed, may be regarded as one of the rnoft important practical truths in medicine. He calls in queftion the propriety of forming opinions of the nature of difeafes by their fymptoms merely, and boldly adopts the method of judging from the " laedentia and juvantia." He offers well-founded criticifm on nosological arrangement, and (hews wherein, through want of diflinctiou between univerfal and local difeafes, a number of thefe had been claffed wrong. On examining the phlogifijc exanthemata he contends, that in meafles xxiv INTRODUCTION TO THE nieafles and fcarlet fever, as well as in fmall-pox, the general indication of cure is to diminim the inflammatory diatheiis, without the leaft re- gard to the particular nature of the contagion, or the ilage of erup- tion ; but thefe are carefully to be dhlmguiihed from the plague, and other eruptive difeafes of a totally oppoiite character : and that with- out attending to the peculiarity of the refpiration, or the precife na- ture of the morbific caufe, the certain things to be attended to are, How far the difeafed condition deviates from health ; and in what de- gree the living body approximates towards death. The exanthema- tons fymptoms in the two claffes of complaints, varying in each, their form only, and not their nature* Having proceeded thus far, he declares that difeafes of the fame type or clafs are to be relieved, or cured, by the fame mode of treat- ment ; and that the volumes of diagnoftics, and the endlefs diftinc- tiona of nofology, in ipite of the authority of even Baglivi and Syd- enham, when oppofed to clear reafon and matter of fact, ought to be disregarded. He expreifes his appreheniions too, left the infinite dif- cinclion of difeafes mould lead to a mode of practice equally diverii- fied. and have a very baneful effect upon materia medica and pre- scriptions. * In his remarks upon predifpufition to bad health, he avers that no perfon ever fuddenly became lick, but that gradually a predifpoktion was created by the agency of the exciting powers, and but of this pre- difpofition grew the difeafe. Of this he gives examples in the phlogif- tic exanthemata, wherein he fays, a high degree of excitement pro- duces the difeafe, a lower predifpolition, and a dill lower health : the means, therefore, conducive to the latter of thefe he thinks fo iimple, that the ufe of the common nofology is intirely fuperfeded. Proceeding upon this plan, he diftinguifhes local from univerfal ailments ; both of which are confufedly claffcd together, in the differ- ent nofological arrangements. This led him to an examination of hemorrhagy, which, if attended in the beginning with phlogiftic diatheiis, he thought always became eventually afthenic, and in this enquiry it was that he was induced to call in queftion the exiftence of plethora, as a caufe of hemorrhagy, and to reject: altogether the notion of a vis mtdicatrix naturae as an agent in the animal iyflem. This lirfl edition of the Elementa is an unfinished work, and com- prehends the details of his doctrine no farther than thejlbtnk form of difeafes. Among thefe he there ranks hemorrhagy, efpecially menor- rhagia, haemorrhois, epiftaxis, and apoplexy ; an arrangement /vhich he afterward c< nfidered wrong, and altered accordingly in the fol- lowing editions, by placing them all in the afthenic clafs. Such, he tells us, was the train of ideas palling in his mind as he reflecred upon the animal economy ; a ton thefe confederations idge himfelf warranted in undettal n explanation of the fubjeft, different in many refpe&s from any done before him. , throughout the whole, he nc\<:v defcends beneath his dignity to animadvert upon particular perfotu ; though in certain cafes, AMERICAN EDITION. xxv cafes, where almoft implicit faith and idolatrous reverence had been given to certain authors, he has freely attacked and refuted their opinions. He apologizes for the plainnefs of ftile and manner with which the performance is written, especially, fince to avoid the conta- gion of opinion, he had read no medical book for five whole years, and had fcarcely confulted the monuments of ancient elegance for twenty. There is a great deal of animation and force in his argument againft plethora, from the ninety-fourth to the ninety-eighth fection, which he concludes with this challenge : " Si fit quod ad hoc refpondeas, " refponde Stahli aut jube Junckerum."* In the hundred and fourth fection he oppofes, in decided terms, the tonic or aitringent operation of cold, particularly as caufing conftriction of the fkin ; and repeats the fame in feveral places, (J 180 — 182.) de- nying that it acts as a ftimulant. In his reafoning againft lentor in the fluids as a caufe of difeafe, he breaks out into the following fpirited exclamation t " Quam infelix <* ea pathologia eft ! cujus perpetuum principium, quod univerfis " comprehends partibus convenire, univerfas illuftrare, et explicare " debet, ne uni quidem convenit, unam illuftrat, unam explicat, con- (l tra omnibus repugnat, omnes obfeurat, et confundit ;" and, reject- ing the pathology of the fluids, declares, that cool water, pure air, wine, and Peruvian bark refift putrefaction in no other way than by keeping up excitement. In his remarks upon fpafm, he endeavours to mew that it cannot be a caufe of difeafe, either of the fthenic or afthenic kind, and ought, of courfe, to be rejected from both, as fhould alfo what has been called the reaction of the fyjlem, in fever. In the courfe of his animated ar- gument, he afks if, toward the end of the eighteenth century, " quis, " opinionem meram, nulla rationis, nulla veri vel tenuifiima umbra com- " mendatam, folidiflimis argumentis, item ipfi tuendae adhibitis corn-* ** pertam falfam, poft vanam omni falfae logicse genere defenfionem, " pro re vera et certa oblatum iri crederet V He is every where oppofed to that claflification and arrangement of difeafes which has fo much obtained of late, and clofes this work with the words, " Nofologia delenda." He publifhed a fecond edition in the year 1784, and added thereto the afthenic clafs of difeafes. Taught by experience and obfer- vation, in the different forms of the gout and, aft h ma, of the benefit of ftimulant remedies, he had no hefitation to coniider them among the effects of weaknefs ; as were likewife fevers ftrictly fo called (febres) both intermittent and continued, and all the kinds of hemorrhagy, &c. In fhort, the confederation of the difeafes not belonging to the fthen- ic clafs, convinced him they mult be referred to the afthenic ; fuch were all fpafmodic or convulfive ailments, dyfpepfia, and other the like affections of the alimentary canal, and the greater part of the maladies of children. Vol. I. d In * Note Juncker was the difciple of Si<*h! and the expofitor of his do&rine-i. xxvi INTRODUCTION TO fiOJE In this performance too, he contends againft the advocates for fed- atives. Opium, he declares, has a flimulant operation ; colds or ca- tarrhs are produced by heat fucceeding to cold, and not vice verfa ; and extends his laws of animation to the vegetable creation. In fhort, he concluded there was in the medullary nervous matter, and niufcular folid of living bodies, which have been generally called the nervous fyflem, a property by which they could be affected by outward agent?, as well as by their own functions, in fuch away as to produce the phenomena peculiar to the living (late. This capacity of beinc acted upon is termed excitability, and the agents are all denom- inate djlim ulant s, while the effect produced by the operation of flimu- lants upon excitability is called excitement. Excitement is terminated in two ways. i. By the exhauftion of excitability, through the violence c-r continuance of flimulus, which is called irvMrccl debility, 2. By the accumulation of excitability, through deficient Itimulus, which is termed direcl debility. Between the two extremes of indirect and direct debility are experienced both health and dileafe6 of the fthenic kind, or thofe febrile complaints (py- rexia;,) accompanied with what has been called phlogiftic diathefis, wherein, though the excitement confiderably exceeds the healthy rate, ftill it does not reach the limits of indirect debility. Stimuli lofe their efficacy after long and frequent application ; but even then the excitability, exhaufled in relation to one itimulus, is ca- pable of being acted upon by another. Therefore, the waile of excitability, after exhauftion of one flimu- lus after another, is very hard to be repaired, by reafon of the difficul- ty of accefs to frefh ftimuli to work upon the languishing excitability ; which, by being applied ftrong at firft, and gradually weakened after- wards, anfwers the purpofe ; and alfo the fuperabundant excitabili- ty left by fubduction of one flimulus after another, produces fuch an excitable condition of the fyflem, that much nicety is requifite to wear it gradually away by application of very weak flimuli at firft, and by degrees flronger and flronger, until the aceuilomed ones can be com- fortably borne. According to the Brunonian Doctrine difeafes ap- pear under various modifications, as exhibited in the table below. Thus they may be, 1. Univerfal, fuch as primarily affect the whole conftitution, as fe- vers, Zlq.. 2. Local, where, from limited morbid affection, a particular part labours, without difordering the intire habit ; as trifling wounds, phlegmons, occ. 5. Loeo-univcrial, when, from a local affection, the whole body is eventually brought into a dii'eafed condition ; as in lues originat- ing from chancre, fmall-pox from inoculation, &c. 4. Tlmverfo-local ; as if after a general ailment any particular part or organ is affected in a fecondary way ; as the eruptions of exan- ; matous pyrexia, fyphilitic blotches, &c. Anf' each of thefe forms of difeafes muff coniiil either in, l. I >ire& debility ; as in fcurvy, hunger, cold, &c. 2, StheiH- AMERICAN EDITION. xxvii 2. Sthenic diatheSis ; as in plcurify, other forms of Synocha, &c, 3. Indirect debility ; as in old age, intoxication, fatigue, Sec. 4. Direct debiKty added to indirect ; as in gout very often, and in many difeafes of advanced life. 5. Indirect debility added to direct ; as in over-feeding a familhed perfon, &c. in moft difeafes of infants and young perlbns. Let now the candid reader compare this view with the opinions of the old Methodists, and fay, whether it be a mere revival of the practice of Thjemison and Thessalus ? Surely they who have af- Serted it was, can never be fupp6fed to have given themfelves the trou> ble to examine. Yet, with all this novelty about it, Brown's doctrine wants pre- cision. It proceeds not far enough beyond general principles, which, by reafon of their abftract or fpeculative nature, have not been found cloSely enough applicable to the fubjects of pathology and phyfiology. He takes for granted, for in fiance, that the nervous Syftem is always one and the fame excitable thing. He fays fcarcely any thing accurate 0:1 the different qualities of the blood and circulating fluids, and of the feci e- tions ; and gives nothing very minute concerning the mighty influence of the refpiratory and digeftive proceffes upon the animal ceconomy. He pafTes over entirely the chemical compofition of our food and drink, of our inhalations and excretion?, of the gafes we breathe and the remedies we fwallow : in fhort, he' has left not a fentence on the compofition or the nature of bone, mufcle, veffel, fat, lymph, or gluten, nor how varioufly thefe are affected by difeafe, nor in what their healthy differs from their morbid flate, nor by what means the alterations they undergo are brought about. Thefe, and other omiffions and defects in the Brunonian System, called for amendment ; and this was to be begun by attending to the varying condition of the living folid, and the concomitant flate of the fluids. The eftablifhment of the new nomenclature of chemiftry in France, m 1787? may be confidered as forming a new epoch in fcience. Since the publication of that invaluable performance, language has been adapted with greater accuracy to the expreflion of ideas, and philo- sophical investigation conducted with Superior advantage and fuccefs. Lavoisier, in his Elements of Chemiftry, has attempted the expla- nation of the putrefactive, as well as the fermentative procefs in the organized forms of animals and of plants, upon the modern principles ; and, in a natural and convincing manner, has proceeded a great way beyond any one who undertook the explanation before. Spallan- zani indeed, in his Experiments on the Concoction of Food in the Stomach, and Crawford, in his Application of the Principles of Combuflion to the Function of the Lungs in breathing, had givejj ex- cellent Specimens oS this mode of reafoning on phyfiological fubjects. Great progreSs has been made Since in detecting' the nature and prop- erties of the atmofphere, the gafes and aeriform fluids ; and the right •knowledge of thefe, derived from experiment and observation, has fur- nil lied xxviii INTRODUCTION TO THE nifhed the means of expounding many of the animal fun&ions, in a plain and happy manner. We do not merely know, at prefent, that there is a gafeous produc- tion, pure air, neceflary to the prefervation and continuance of animal life ; but we think we know it is a compound fubftance, and what its compound ingredients are ; we believe we can make and unmake it ar- tificially, and that nature is doing fo incefTantly : we think the term " dephlogifticated air" not accurately nor logically applied; but, judging from its tendency to produce fournefs when combined with other bodies, we call the bafis of it " the acidifying principle," and the combination of that bafe with light and caloric or the matter of heat, " oxygene gas or air," or more properly " gafeous oxyd of light." From noting the operation of this oxygene, or principle of fouring, upon various bodies, we imagine we know the compofition of ado's, and have made out a confiderable lill of acidifiable bafes; fo that the forma- tion of fixed air from oxygene and carbone, or charcoal, of nitrous acid, from it and azote, of vitriolic acid from the fame and fulphur, and phof- phoric acid from its union with phofphorus, feem to be well eftablifh- ed truths. We imagine that a certain other clafs of bodies capable of combining with oxygene, but not to the point of acidity, forms there* by half-acids or oxyds, and that thus the calces of metals, animal blood and fecretions, as well as the farinaceous, gummy, and mucil- aginous parts of plants, are formed. We think the compofition of water is underflood, and inftead of be* ing an elementary body, as was formerly believed, that it is, in fact, but the oxyde of hydrogen, or a combination of this latter fubftance •with the principle of acidity, but not to the fouring point. It is confidered alfo, that more is known concerning the compofition of the irritable fibre, of the adipofe matter, and of the bones : and that the effects produced upon the circulated fluids by breathing, and through them upon the folids of the animal body in health, and the alterations too that the liquid and firm parts undergo by impeding, vitiating, or obftru&ing that function, in ordinary cafes, as well as in gravid females, are now better comprehended than they ufed to be. Inafmuch, that after the great light thrown upon this fubjec~t, fucceed- ing authors have been enabled to drefs up the Brunonian Syftem in the more recent fafliion, and, to fupply and adorn it with almoft all that ww wanting to make it additionally engaging and attrac- tive. Drowning, fufTocation, fcurvy, (lone, dyfentery, peftilence, ulcers and fever, have already received great elucidation, both in theory and practice, from the application of chemical principles ; and we may reafonably hope, that before many more years elapfe, better and more correct ideas will be entertained of many articles of the materia medica, and of their manner of operating ; that a new medical nomenclature (than which nothing in fcience is more wanting) will be made out ; and that, from the afcertained condition of the body, and the known compofition and operation of remedies, phyficians may prefcribe fairly for the actual ftatc of the constitution, and the removal of the prefent malady, AMERICAN EDITION. xxix malady, without feeing mifled, as too often happens at prefent, by fpe- cious words, and idle or deceitful names. But, notwithstanding the many and beautiful applications of chem- ical principles to the explanation of the animal functions, we are not to imagine every thing in life fufceptible of chemical interpretation. What it is that enables the atoms compofing a mufcle to cohere, and the mufcle to contract and perform great exertions of ftrength, we know not ; but this we know very well, that we can never form a muf- cle by fynthefis, or the putting together, in any artificial form, thofe fubftances which appear, from analylis, to conftitute a mufcle. There is fomething in animated exiftence, which eludes our moft active re- fearches, and which defies fubmiffien to either mechanical or chemical laws. With refpecl to chemical modes of reafoning upon thefe fub- jecls, it is obfervable, that they apply, with their greateft extent and accuracy, to fuch parts of the body as have the loweft degrees of ani- mation, as the contents of the inteflines, the teeth, bones, fat, fubftan- ces adhering to the fkin, and, generally fpeaking, the circulated and fecreted fluids ; while the qualities of mufcular fibres, by which they become contractile, and of nervous expanfions, whereby they take on fenfation, with the whole of the functions arifing from irritability and fenfibility, are referable to other and different laws. The inveftigation of thefe Laws of Organic Life is attempted by our learned and very ingenious author in the following work. The Zoonomia, therefore, though not exempt from fanciful and vifionary doctrines, prefents confiderations of the firft importance, "both to the fpeculative philofopher and the practical phyfician ; to him who con- templates the operations of mind as a fcience, or to him that attends to the corporeal functions as an artift. The fecond part of this work being engaged in an arrangement of difeafes, with their remedies and modes of treatment, will be very acceptable to the practical as well as the theoretical phyfician. After the different projects for methodiz- ing this department of knswledge, which have fucceflively been offer- ed to the public with fo little advancement of true fcience, the friends of medical improvement and of the healing art will joyfully accept of fomething that promifes to lead them from arbitrary fyftem to nat- ural method. And as the diftinclions are founded upon the increafedy decreafed or inverted actions of the moving machinery of the body, it will initantly be perceived how clofely the Brunonian doctrine is inter- woven with the whole fubjeft. It is however to be always borne in mind that on American difeafes the phyiicians of this country have generally written the beft. SAMUEL L. MITCHILL, New York, Nov. 3, 1802. Z O O N O M I a; OR. THE LAWS OF ORGANIC LIFE. PART I. CONTAINING THE IMMEDIATE CAUSES OF ANIMAL MOTIONS, DEDUCED FROM THEIR MORE SIMPLE OR FREQUENT APPEARANCES IN HEALTH, / AND APPLIED TO EXPLAIN THEIR MORE INTRICATE OR UNCOMMON OCCURRENCES IN DISEASES. FELIX, QUI POTUIT R.ERUM COGNOSCERE CAU3AS. • — t— -~-r- — — — rr-r^rr-. ■ -g— vrai1— »"ui»~- a«"'-' -J— ■■!-- 1 —"."g ,'-. nt-^ii. jiB.i > in I. — 1. The nervous fyftem has its origin from the brain, and is diftributed to every part of the body. Thofe nerves, which ferve the fenfes, principally arife from that part of the brain, which is lodged in the head ; and thofe, which ferve the pur- pofes of mufcular motion, principally arife from that part of the brain, which is lodged in the neck and back, and which is erro- neoufly called the fpinal marrow. The ultimate fibrils of thefe nerves terminate in the immediate organs of fenfe and mufcular fibres, and if a ligature be put on any part of their pafTage from the head or fpine, all motion and perception ceafe in the parts beneath the ligature. 2. The longitudinal mufcular fibres compofe the locomotive mufcles, whofe contractions move the bones of the limbs and trunk, to which their extremities are attached. The annular or fpiral mufcular fibres compofe the vafcular mufcles, which con- ftitute the inteftznal canal, the arteries/ veins, glands, and ab- sorbent veftels. 3. The immediate organs of fenfe, as the retina of the eye, probably confifh of moving fibrils, with a power of contraction fimilar to that of the larger mufcles above defcribed. 4. The cellular membrane confifts of ceils, which refemblc thofe of a fponge, communicating with each other, and con*- necking together all the other parts of the body. 5. The arterial fyftem confifts of the aorta and the pulmona- ry artery, which are attended through their whole courfe with their 4 DEFINITIONS. Sect. II. i. <5. their correfpcndent veins. The pulmonary artery receives the blood from the right chamber of the heart, and carries it to the minute extenfive ramifications of the lungs, where it is expofed to the action of the air on a furface equal to that of the whole external (kin, through the thin moid coats of thofe vefTels, which are fpread on the air-cells, which constitute the minute terminal ramifications of the wind-pipe. Here the blood changes its colour from a dark red to a bright fcarlet. It is then collected by the branches of the pulmonary vein, and conveyed to the left chamber of the heart. 6. The aorta is another large artery, which receives the blood from the left chamber of the heart, after it has been thus aera- ted in the lungs, and conveys it by afcending and defcending branches to every part of the fyftem •, the extremities of this ar- y terminate either in glands, as the falivary glands, lachrymal glands, &c. or in capillary vefTels, which are probably lefs invo- luted glands; in thefe fomc fluid, as faliva, tears, perfpiration, is ieparated from :he blood; and the remainder of the blood is abforbed or drank up by branches of veins correfpondent to the branchesof the artery; which are furnifhed with valves to prevent its return ; and is thus carried back, after having again changed its colour to a dark red, to the rieht chamber of the heart. The circulation of the blood in the liver differs from this general fyf- tem ; for the veins which drink up the refluent blood from thofe arteries, which fpread on the bowels and mefentery, unite into a trunk in the liver, and form a kind of artery, which is branch- ed into the whole fubitance of the liver, and is called the vena portarum ; and from which the bile is feparated by the numer- hepatic glands, which conftilute that vifcus. 7. The glands may be divided into three fy (terns, the convo- luted glands, fuch as thofe above defcribed, which feparate bile, tears, faliva, &c. Secondly, the glands without convolution, as the capillary vefTels, which unite the terminations of the arteries and veins; and feparate both the mucus, which lubricates the cel- lular membrane, and the perfpirable matter, which preferves the Ikin moift and flexible. And thirdly, the whole abforbent fyftem, confuting of the lacteals, which open their mouths into the ftom- ach and inteftines, and of the lymphatics, which open their mouths on the external furface of the body, andon the internal linings of all ie cells of the cellular membrane, anil other cavities of the body. Thefe lacteal and lymphatic vefTels are furnifhed with nu- merous valves to prevent the return of the fluids, which they abforb, and terminate in glands, called lymphatic glands, and may hence be confidered as long necks or mouths belonging to nds. To thefe they convey the chyle and mucus, with a Sect. II. i. 8. DEFINITIONS, 5 a part of the perfpirable matter, and atmofpheric moiflure $ all which, after having paiTed through thefe glands, and having fufFered foine change in them, are carried forward into the blood, and fupply perpetual nourifhment to the fyitem, or re- place its hourly waile. 8. The ftomach and inteftinal canal have a conftant vermic- ular motion, which carrier forwards their contents, after the lacleals have drank up the chyle from them ; and which is ex- cited into action by the ftimulus of the aliment we fwallow, but which becomes occasionally inverted or retrograde, as in vomit- ing, and in the iliac paflion. II. 1. The word fenforium in the following pages is defign- ed to exprefs not only the medullary part of the brain, fpinal marrow, nerves, organs of fenfe, and of the mufcles ; but alfo at the fame time that living principle, or fpirit of animation, which reiides throughout the body, without being cognizable to our fenfes, except by its effects. The changes which occafion- aily take place in the fenforium, as during the exertions of voli- tion, or the fenfations of pleafure or pain, are termed fenforial motions. 2. The fimilarity of the texture of the brain to that of the pancreas, and fome other glands of the body, has induced the inquirers into this fubjeel: to believe, that a fluid, perhaps much more fubtiie than the electric aura, is feparated from the blood by that organ for the purpofes of motion and fenfatipn. When we recollect, that the electric fluid itfeif is actually accumulated and given out voluntarily by the torpedo and the gymnotus elec- tric us, that an electric mock will frequently llimulate into mo- tion a paralytic limb, and laitly that it needs no perceptible tubes to convey* it, this opinion feems not without probability ; and the fingular figure of the brain and nervous fyitem feems well adapted to diftribute it over every part of the body. For the medullary fubftance of the brain not only occupies the cavities of the head and fpine, but palfes along the innumer- able ramifications of the nerves to the various mufcles and or- gans of fenfe. In thefe it lays afide its coverings, and is inter- mixed with the {lender fibres, which conuVitute thofe mufcles and organs of fenfe. Thus all thefe diftant ramifications of the fenforium are united at one of their extremities, that is, in the headsand fpine ; and thus thefe central parts of the fenforium conftitute a communication between all the organs of fenfe and mufcles. 3. A nerve is a continuation cf the medullary fub fiance of the brain from the head or fpine towards the other parts of the body, wrapped in its proper membrane. 4. The 6 DEFINITIONS. Sect. II. 2. 4. 4. The mufcuhr fibres are moving organs intermixed with that medullary fubftance, which is continued along the nerves, as mentioned above. They are indued with the power of contrac- tion, and are again elongated either by antagonift mufcles, by circulating fluids, or by elaftic ligaments. So the mufcles on one fide of the fore-arm bend the fingers by means of their ten- dons, and thofe on the other fide of the fore-arm extend them again. The arteries are diftended by the circulating blood ; and in the necks of quadrupeds there is a ftrong elaftic liga- ment, which afiifts the mufcles, which elevate the head, to keep it in its horizontal pofition, and to raife it after it has been de- preiTed. 5. The immediate organs of fenfe confift in like manner of moving fibres enveloped in the medullary fubftance above men- tioned ; and are erroneoufly fuppofed to be fimply an expanfion of the nervous medulla, as the retina of the eye, and the rete mucofum of the fkin, which are the immediate organs of vifion, and of touch. Hence when we fpeak of the contractions of the fibrous parts of the body, v/e fhall mean both the contractions of the mufcies, and thofe of the immediate organs of fenfe. Thefe fibrous motions are thus diftinguifhed from the fenforial motions above mentioned. 6. The external organs of fenfe are the coverings of the im- mediate organs of fenfe, and are mechanically adapted for the reception or tranfmiflion.of peculiar bodies, or of their qualities, as the cornea and humours of the eye, the tympanum of the ear, the cuticle of the fingers and tongue. 7. The word idea has various meanings in the writers of metaphyfic : it is here ufed fimply for thofe notions of external things, which our organs of fenfe bring us acquainted with orig- inally ; and is defined a contraction, or motion, or configuration, of the fibres, which conftitute the immediate organ of fenfe ; which will be explained at large in another part of the work. Synonymous with the word idea, we (hall fometimes ufe the words fenfual motion in contradiftinction to mufcular motion. 8. The word perception includes both the action of the or^an of fenfe in confequence of the impact of external objects, and our attention to that action ; that is, it exprefles both the motion of the organ of fenfe, or idea, and the pain or plcafure that fuc- ceedsor accompanies it. 9. The pleafure or pain which necefiarily accompanies all thofe perceptions or ideas which we attend to, either gradually fubfides, or is fuccceded by other fibrous motions. In the latter cafe it is termed Jen/at ion, as explained in Sect. V. 2, and VI. e reader is intreatcd to keep this in his mind, that through Sect. II. 2. 10. DEFINITIONS. 7 through all this treatife the word fenfation is ufed to exprefs pleafure or pain only in its active ft ate, by whatever means it is introduced into the fyftem, without any reference to the ftimu- lation of external objects. 10. The vulgar ufe of the word memory is too unlimited for our purpofe : thofe ideas which we voluntarily recall are here termed ideas of reco/Ieclion, as when we will to repeat the alpha- bet backwards. And thofe ideas which are fuggefted to us by preceding ideas are here termed ideas of fuggef.ion^ as whilft we repeat the alphabet in the ufual order ; when by habits previ- oufly acquired B is fuggefted by A, and C by B, without any effort of deliberation. 1 1 . The word affbciation properly fignifies a fociety or con- vention of things in fome refpects fimilar to each other. We never fay in common language, that the effect is aflbciated with the caufe, though they neceflarily accompany or fucceed each other. Thus the contractions of our mufcles and organs of fenfe may be faid to be aflbciated together, but cannot with pro- priety be faid to be aflbciated with irritations, or with volition^ or with fenfation ; becaufe they are caufed by them, as men- tioned in Sect:. IV. When fibrous contractions fucceed other fibrous contractions, the connexion is termed affociation ,• when fibrous contractions fucceed fenforial motions, the connexion is termed caufation ; when fibrous and fenforial motives recipro- cally introduce each other in progreffive trains or tribes, it is termed catenation of animal motions. All thefe connexions are faid to be produced by habit ; that is, by frequent repetition. 1 2. It may be proper to obferve, that by the unavoidable idi- om of our language the ideas of perception, of recollection, or of imagination, in the plural number fignify the ideas belonging to perception, to recollection, or to imagination ; whilft the idea of perception, of recollection, or of imagination, in the lingular number is ufed for what is termed « a reflex idea of any of thofe operations of the fenforium." 13. By the v/ord Jlimulus is not only meant the application of external bodies to our organs of fenfe and mufcular fibres, which excites into action the fenforial power termed irritation ; but al- fo pleafure or pain, when they excite into action the fenforial power termed fenfation ; and defire or averfion, when they ex- cite into action the power of volition ; and laftly, the fibrous contractions which precede aflbciation ; as is further explained in Sect. XII. 2. 1. MOTIONS OF Sect. III. i. i SECT. III. THE MOTIONS OF THE RETINA DEMONSTRATED BY EXPERI- MENTS. I. Of animal motions and of ideas. II. The fibrous firuBure of the retina. III. The aBiviiy of the retina in v'fion. I. Rays of light hove no momentum. 2. Objects long viewed become fainter. 3. Sped r a of black objects become luminous. 4. Varying fpeBra from gyration. 5. From long infpeBion of various colours. IV. Motions of the organs of fenfe confiitute ideas. 1 . Light from pi effing the eye-ball, and found from the pulfation of the carotid ar- tery. 2. Ideas in fieep mifiaken for perceptions. 3. Ideas of im- agination produce pain andficknefs like fen fations. 4. When the organ of fenfe is defiroyed, the ideas belonging to that fenfe perifh. V. Analog") between mufcular motions and fenfual motions, or ideas. 1. %hey are hot;: originally excited by irritations. 2. And officiated together in the fame manner, 3. Both act in nearly the fame times. 4. Are alike firengthened or fatigued by exercife. 5. Are alike painful from inflammation. 6. Are alike benumb- ed by comprejfion. 7. Are alike liable to parahfts. 8. To con- njufion. 9. To the influence of old age. — VI. ObjeBions anfwered. I. Why we cannot invent new ideas. 2. If ideas refemble exter- nal object s. 3. Of the imagined fen fation in an amputated limb. 4. Alfiracl ideas. — VII. What are ideas, if they are not ani- mal motions ? Before the great variety of animal motions can be duly ar- ranged into natural claiTes and orders, it is neceffary to fmooth the way to this yet unconquered field of fcience, by removing fome obstacles which thwart our paffage. I. To demonftrate that the retina and other immediate organs of fenfe pofTefs a power of motion, and that thefe motions conftitute our ideas, according to the fifth and feventh of the preceding afTertions, claims our firft attention. Animal motions are diftinguiihed from the communicated motions, mentioned in the firft fection, as they have no me- chanical proportion to their caufe \ for the goad of a fpur on the &in of a hcrfe ftiall induce him to move a load of hay. They diircr from the gravitating motions there mentioned as they arc with equal facility in all directions, and they differ from e chemical clafs of motions, becaufe no apparent decompofi- - o;- new combinations are produced in the moving ma- is, Hence, Sect. III. m. THE RETINA. $ Hence, when we fay animal motion is excited by irritation, wa do not mean that the motion bears any proportion to the me- chanical impulfe of the ftlmulus ; nor that it is affected by the general gravitation of the two bodies ; nor by their chemical properties 5 but folely that certain animal fibres are excited in- to action by fomething external to the moving organ. In this fenfe the ftimulus of the blood produces the contrac- tions of the heart ; and the fubftances we take into our ftomach and bowels ftimulate them to perform their neceffary functions. The rays of light excite the retina into animal motion by their ftimulus ; at the fame time that thofe rays of light tfiernfelves are phyfically converged to a focus by the inactive humours of the eye. The vibrations of the air ftimulate the auditory nerve into animal action ; while it is probable that the tympanum o£ the ear at the fame time undergoes a mechanical vibration. To render this circumftance more eafy to be comprehended, motion may be defined to be a variation of figure ; for the whole univerfe may be confidered as one thing pofiefling a certain fig- ure ; the motions of any of its parts are a variation of this fig- ure of the whole : this definition of motion will be further ex- plained in Section XIV. 2. 2. on the production of ideas. Now the motions of an organ of fenfe are a fucceffion of con- figurations of that organ ; thefe configurations fucceed each other quicker or flower ; and whatever configuration of this or- gan of fenfe, that is, whatever portion of the motion of it is, or has ufually been, attended to, conftitutes an idea. Hence the configuration is not to be confidered as an effect of the motion of the organ, but rather as a part or temporary termination of it j and that, whether a paufe fucceeds it, or a new configuration immediately takes place. Thus when a fucceffion of moving objects are prefented to our view, the ideas of trumpets, horns, lords and ladies, trains and canopies, are configurations, that is, parts or links of the fucceflive motions of the organ of vifion. Thefe motions or configurations of the organs of fenfe differ from the fenforial motions to be defcribed hereafter, as they ap- pear to be fimply contractions of the fibrous extremities of thofe organs, and in that refpect exactly referable the motions or con- tractions of the larger mufcles, as appears from the following experiment. Place a circular piece of red filk about an inch in diameter on a fheet of white paper in a ftrong light, as in Plate I.-— look for a minute on this area, or till the eye becomes fome- what fatigued, and then, gently clofing your eyes, and fnading them with your hand, a circular green area of the fame appar- ent diameter becomes vifible in the clofed eye. This green area is the colour reverfe to the red area, which had b^tn pre- vol. I. C viouilv lb MOTIONS OF Sect. III. 2. 1, vioufly infpected, as explained in the experiments on ocular fpectra at the end of the work, and in Botanical Garden, P. I. additional note, No. I. Hence it appears, that a part of the ret- ina, which had been fatigued by contraction in one direction, relieves itfelf by exerting the antagonift fibres, and producing a contraction in an oppofite direction, as is common m the exer- tions of our mufcles. Thus when we arc tired with long ac- tion of our arms in one direction, as in holding a bridle on a tourney, we occafionaily throw them into an oppofite pofition to relieve the fstigued mufcles. Mr. Locke has defined an idea to be fC whatever is prefent to the mind 5" but this would include the exertions of volition, and the fenfations of pleafure and pain, as well as thofe opera- ti ms of our fyftem, which acquaint us with external objects ; and is therefore too unlimited for our purpofe. Mr. Locke feerns to have fallen into a further error, by conceiving, that the mind could form a general or ab (tract idea by its owii operation, which was the copy of no. particular perception ; as of a triangle in general, that was neither acute, obtufe, nor right angled. The ingenious Dr. Berkley and Mr. Hume have demonstrated, that fuch general ideas have no exiftence in na- ture, not even in the mind of their celebrated inventor. We fhall therefore take for granted at prefent, that our recollection or imagination of external objects confifts of a partial repetition of the perceptions, which were excited by thofe external ob- jects, at the time we became acquainted with them ; and that our reflex ideas of the operations of our minds are partial repeti- tions of thofe operations. II. The following article evinces that the organ of vifion con- fifts of a fibrous part as well as of the nervous medulla, like oth- er white mufcles ; and hence, as it refembles the mufcular parts of the body in its ftructure, we may conclude, that it mult re- femble them in poiTeffmg a power of being excited into animal motion. The fubfequent experiments on the optic nerve, and on the colours remaining in the eye, are copied from a paper on ocular fpectra publifhed in the feventy fixth volume of the Phi- lof. Tranf. by Dr. R. Darwin of Shrewsbury ; which, as I fliali have frequent occafion to refer to, is reprinted in this work, Sect. XL. — The retina of an ox's eye was fufpended in a glafs of warm water, and forcibly torn in a few places ; the edges of thefe parts appeared jagged and hairy, and did not contract and ne fmooth like fimple mucus, when it is diftended till it breaks 5 which evinced that it confided of fibres. This fibrous conftruction became ltill more diftinct to the fight by afflding fvme cauilic alkali to the water \ 39 the adhering mucos was firft / Sect. III. 3. 1. THE RETINA. n firft eroded, and the hair like fibres remained floating in the vef- fel. Nor does the degree of tranfparency of the retina invali- date this evidence of its fibrous ftructure, fince Leeuwenhoek has fhewn, that the cryft aline humour itfelf confiits of fibres. Arc. Nat. V. I. 70. Hence it appears, that as the mufcles confift of larger fibres intermixed with a fmaller quantity of nervous medulla, the or- gan of vilion confiftsof a greater quantity of nervous medulla intermixed with fmaller fibres. It is probable that the locomo- tive mufcles of microlcopic animals may have greater tenuity than thefe of the retina -, and there is reafon to conclude from analogy, that the other immediate organs of fenfe, as the portio mollis of the auditory nerve, and the rete mucofum of the fkin, poflefs a fimilarity of ftructure with the retina, and a fimilay power of being excited into animal motion. III. The fubfequent articles mew, that neither mechanical imprefiions, nor chemical combinations of light, but that the animal activity of the retina conftitutes vifion. 1. Much has been conjectured by philofophers about the momentum of the rays of light ; to fubject this to experiment a very light horizontal balance was cbnftructed by Mr. Michel, with about an inch fquare of thin leaf-copper fufpended at each end of it, as defcribed in Dr. Prieftley's Hiftory of Light and Colours. The focus of a very large convex mirror was thrown by Dr. Powel, in his lectures on experimental philofophy, in my prefence, on one wing of this delicate balance, and it reced- ed from the light ; thrown on the other wing, it approached towards the light, and this repeatedly ; fo that no fenfible irn- pulfe could be obferved, but what might well be afcribed to the afcent of heated air. Whence it is reafonable to conclude, that the light of the day mult be much too weak in its dilute ftate to make any mechan- ical impreilion on fo tenacious a fubftance as the retina of the eye. — Add to this, that as the retina is nearly tranfparent, it could therefore make lefs refrilance to the mechanical impulfe of light ; which, according to the obfervations related by Mr. Melvil in the Edinburgh Literary EfTays, only communicates heat, and fhould therefore only communicate momentum, where it is ohftructed, reflected, or refracted. — From whence alfo may be collected the final caufe of this degree of tranfpar- ency of the retina, viz. left by the focus of ftronger lights, heat and pain fhould have been produced in the retina, inftead of that itimulus which excites it into animal motion. 2. On looking long on an area of fcarlet filk of about an inch in diameter laid on white paper, as in Plate I. the fcarlet colour becomes i a MOTIONS OF Sect. III. 3. 3. becomes fainter, till at length it entirely vanifhes, though the eye is kept uniformly and fteadily upon it. Now if the change or motion of the retina was a mechanical impreflion, or a chem- ical tinge of coloured light, the perception would every minute become ftronger and ftronger, — whereas in this experiment it becomes every inftant weaker and weaker. The fame circum- ftance obtains in the continued application of found, or of fapid bodies, or of odorous ones, or of tangible ones, to their adapted organs of fenfe. Thus when a circular coin, as a (hilling, is preffed on the palm of the hand, the fenfe of touch is mechanically comprefE. ed 5 but it is the ftimulus of this prefTure that excites the organ of touch into animal action, which conflitutes the perception of hardncfs and of figure : for in fome minutes the perception ceafesj though the mechanical prefTure of the object remains. 3. Make with ink on white paper a very black fpot about half an inch in diameter, with a tail about an inch in length, fo as to refemble a tadpole, as in Plate II. ; look fteadfaftly for a minute on the centre of this fpot, and, on moving the eye a lit- tle, the figure of the tadpole will be feen on the white part of the paper ; which figure of the tadpole will appear more lumi- nous than the other part of the white paper ; which can only be explained by fuppofing that part of the retina, on which the tadpole was delineated, to have become more fenfible to light than the other parts of it, which were expofed to the white paper ; and not from any idea of mechanical impreflion or chemical combination of light with the retina. 4. When any one turns round rapidly, till he becomes dizzy, and falls upon the ground, the fpectra of the ambient objects continue to prefent themfelves in rotation, and he feems to be- hold the objects itill in motion. Now if thefe fpectra were im- preflions on a paffive organ, they either mud continue as they were received laft, or not continue at all. 5. Place a piece of red filk about an inch in diameter on a flieet of white paper in a ftrong light, as in Plate I. •, look ftead- ily upon it from the diflance of about half a yard for a minute ; then clofing your eye-lids, cover them with your hands and handkerchief, and a green fpectrum will be feen in your eyes refembling in form the piece of red filk. After fome feconds of time the fpectrum will difappear, and in a few more feconds will reappear ; and thus alternately three or four times, if the experiment be well made, till at length it vanifhes entirely. 6. Place on a fheet of white paper a circular piece of blue filk, about four inches in diameter, in the funfhine ; cover the r of this with a circular piece of yellow filk, about three inches Sect. III. 4. *• THE RETINA. 13 inches in diameter ; and the centre of the yellow filk with a circle of pink filk, about two inches in diameter ; and the cen- tre of the pink filk with a circle of green filk, about one inch in diameter ; and the centre of this with a circle of indigo, about half an inch in diameter ; make a fmall fpeck with ink in the very centre of the whole, as in Plate III. look fteadily for a min- ute on this central fpot, and then clofing your eyes, and applying your hand at about an inch diftance before them, fo as to pre- vent too much or too little light from paffing through the eye- lids, and you will fee the moil beautiful circles of colours that imagination can conceive j which are mod refembled by the colours occafioned by pouring a drop or two of oil on a Hill lake in a bright day. But thefe circular irifes of colours are not only different from the colours of the filks above mention- ed, but are at the fame time perpetually changing as long as they exift. From all thefe experiments it appears, that thefe fpecVra in the eye are not owing to the mechanical impulfe of light im- prefled on the retina •, nor to its chemical combination with that organ ; nor to the abforption and emiflion of light, as is fuppofed, perhaps erroneoufly, to take place in calcined (hells and other phofphorefcent bodies, after having been expofed to the light : for in all thefe cafes the fpeclra in the eye fhould ei- ther remain of the fame colour, or gradually decay, when the object is withdrawn ; and neither their evanefcence during the prefence of the object, as in the fecond*experiment, nor their "change from dark to luminous, as in the third experiment, nor their rotation, as in the fourth experiment, nor the alternate prefence and evanefcence of them, as in the fifth experiment, nor the perpetual change of colours of them, as in the lad ex- periment, could exift. IV. The fubfequent articles fhew, that thefe animal motions or configurations of our organs of fenfe conftltute our ideas. 1. If any one in the dark prefles the ball of his eye, by ap- plying his finger to the external corner of it, aluminous appear- ance is obferved j and by a fmart ftroke, on the eye great flames of fire are perceived. (Newton's Optics. ) So when the arteries, that are near the auditory nerve, make ftronger pulfations than ufual, as in fome fevers, an undulating found is excited in the ears. Hence it is not the prefence of the light and found, but the motions of the organ, that are immediately neceiTary to con- ilitute the perception or idea of light and found, 2. During the time of fleep, or in delirium, the ideas of im- agination are miftaken for the perceptions of external objects ; whence it appears, that thefe ideas of imagination are no other than 14 MOTIONS OF Sect. III. 4. 3, than a reiteration of thofe motions of the organs of fenfe, which were originally excited by the itimulus of external objects : and in our waking hours the fimple ideas, that we call up by recol- lection or by imagination, as the colour of red, or the fmell of a rofe, are exact refemblances of the fame fimple ideas from perception ; and in confequence mull be a repetition of thofe very motions. 3. The difagreeable fenfation called the tooth-edge is origin- ally excited by the painful jarring of the teeth in biting the edge of the glafs, or porcelain cup, in which our food was given us in our infancy, as is further explained in the Section XVI, 10, on Inftinct.— This difagreeable fenfation is afterwards excited not only by a repetition of the found, that was then produced, but by imagination alone, as I have myfelf frequently experien- ced ; in this cafe the idea of biting a china cup, when I imagine it very diftinctly, or when I fee another perfon bite a cup or glafs, excites an actual pain in the nerves of my teeth. So that this idea and pain feem to be nothing more than the reiterated motions of thofe nerves, that were formerly fo difagreeably af- fected. Other ideas that are excited by imagination or recollection in many inftances produce fimilar effects on the conititution, as our perceptions had formerly produced, and are therefore un- doubtedly a repetition of the fame motions. A (lory which the celebrated Baron Van Swieten relates of himfelf is to this pur- pofe. He was prcfent when the putrid carcafs of a dead dog exploded with prodigious ftench ; and fome years afterwards, accidentally riding along the fame road, he was thrown into the fame ficknefs and vomiting by the idea of the ftench, as he had before experienced from the perception of it. 4. Where the organ of fenfe is totally deftroyed, the ideas which were received by that organ feem to perifh along with it, "3 well as the power of perception. Of this a fatisfactory in- ftance has fallen under my observation. A gentleman about fixty years of age had been totally deaf for near thirty years : he appeared to be a man of good underftanding, and amufed himfelf with reading, and by converfing either by the ufe of the pen, or by figns made with his fingers, to represent letters. I 1 that he had fo far forgot the pronunciation of the lan- ^ that when he attempted to fpeak, none of his words had ct articulation, though his relations could fometimes un- dcrfland his meaning. But, which is much to the point, he af- fured mc, that in his drenms he always imagined that people converfed wii n by figns or writing, and never that he >ne fpeak to hii From hence it appears, that with the Sect. III. 5. 1. THE RETINA. t$ the perceptions of founds he has alfo loft the ideas of them 5 though the organs of fpeech Hill retain fomewhat of their ufual habits of articulation. This obfervation may throw fome light on the medical treat- ment of deaf people ; as it may be learnt from their dreams whether the auditory nerve be paralytic, or their deafnefs be owing to fome defect of the external organ* It rarely happens that the immediate organ of vifion is per- fectly deftroyed. The rnofl frequent caufes of blindnefs are occasioned by defects of the external organ, as in cataracts and obfufcations of the cornea. But I have had the opportunity of converting with two men, who had been fome years blind ; one of them had a complete gutta ferena, and the other had loft the whole fubftance of his eyes. They both told me that they did not remember to have ever dreamt of vifible objects, fince the total lofs of their fight. V. Another method of difcovering that our ideas are animal motions of the organs of fenfe, is from confidering the great analogy they bear to the motions of the larger mufcles of the body. In the following articles it will appear that they are orig- inally excited into action by the irritation of external objects like our mufcles ; are aflbciated together like our mufcular mo- tions ; act in fimilar time with them ; are fatigued by continu- ed exertion like them ; and that the organs of fenfe are fubject to inflammation, numbnefs, palfy, convuliion, and the defects of old age, in the fame manner as the mufcular fibres. 1. All our perceptions or ideas of external objects are uni- verfally allowed to have been originally excited by the ftimulus of thofe external objects ; and it will be fhewn in a fucceeding fection, that it is probable that all our mufcular motions, as welt thofe that are become voluntary as thofe of the heart and glan- dular fyftem, were originally in like manner excited by the ftim- ulus of fomething external to the organ of motion. 2. Our ideas are alfo aflbciated together after their produc- tion precifely in the fame manner as our mufcular motions j which will likewife be fully explained in the fucceeding fection. 3. The time taken up in performing an idea is likewife much the fame as that taken up in performing a mufcular motion* A mufician can prefs the keys of an harpfichord with his fingers in the order of a tune he has been accuftomed to play, in as little time as he can run over thofe notes in his mind. So we many times in an hour cover our eye-balls with our eye-lids without perceiving that we are in the dark ; hence the percep- tion or idea of light is not changed for that of darknefs in fb fmall a time as the twinkling of an eye 5 fo that in this cafe the mufcular 16 MOTIONS OF Sect. III. 5. 4. mufcular motion of the eye-lid is performed quicker than the perception of light can be changed for that of darknefs.— -So if a fire-Hick be whirled round in the dark, a luminous circle ap- pears to the obferver ; if it be whirled fomewhat flower, this circle becomes interrupted in one part ; and then the time taken %»p in fuch a revolution of the flick is the fame that the obferver ufes in changing his ideas : thus the "hoXiy^y.^ ty%o$ of Homer, the long iliadow of the flying javelin, is elegantly defigned to give us an idea of its velocity, and not of its length. 4. The fatigue that follows a continued attention of the mind to one object is relieved by changing the fubjetl: of our thoughts; as the continued movement of one limb is relieved by moving another in its ftead. "Whereas a due exercife of the faculties of the mind flrengthens and improves thofe faculties, whether of imagination or recollection ; as the exercife of our limbs in dancing or fencing increafes the ftrength and agility of the muf- cles thus employed. 5. If the mufcles of any limb are inflamed, they do not move •without pain 5 fo when the retina is inflamed, its motions alfo are painful. Hence light is as intolerable in this kind of oph- thalmia, as preiTure is to the finger in the paronychia. In this difeafe the patients frequently dream of having their eyes pain- fully dazzled ; hence the idea of ftrong light is painful as well as the reality. The firft of thefe facls evinces that our percep- tions are motions of the organs of fenfe ; and the latter, that our imaginations are alfo motions of the fame organs. 6. The organs of fenfe, like the moving mufcle9, are liable to become benumbed, or lefs fenfible, from cornpreflion. Thus, if any perfon on a light day looks on a white wall, he may per- ceive the ramifications of the optic artery, at every pulfation of it, reprefented by darker branches on the white wall ; which is evidently owing to its comprefling the retina during the diaftole of the artery. Sauvages Nofolog. 7. The organs of fenfe and the moving mufcles are alike lia- ble to be affected with palfy,.as in the gutta ferena, and in fome cafes of deafnefs j and one fide of the face has fometimes loft its power of feniation, but retained its power of motion ; other parts of the body have loft their motions, but retained their fen- fation, as in the common hemiplegia ; and in other inftances both thefe powers have perilhed together. 8. In fome convulfive difeafes a delirium or infanity fuper- venes, and the convulfions ceafe ; and converfely the convul- Jions (hall fupervene, and the delirium ceafe. Of this I have been a witnefs many times in a day in the paroxyfms of violent fpilepfies ; which evinces that one kind of delirium is a convul- fion Sect. III. 5. & THE RETINA, 1 7 Hon of the organs of fenfe, and that our ideas are the motions of thefe organs : the fubfequent cafes will illuftrate this obfer- vation. Mifs G , a fair young lady, with light eyes and hair, was feized with moil violent convulfions of her limbs, with outra- geous hiccough, and moft vehement efforts to vomit : after near an hour was elapfed this tragedy ceafed, and a calm talkative delirium fupervened for about another hour ; and thefe relieved each other at intervals during the greateft part of three or four days. After having carefully confidered this difeafe, I thought the convulfions of her ideas lefs dangerous than thofe of her mufcles ; and having in vain attempted to make any opiate continue in her ftomach, an ounce of laudanum was rubbed along ilhe fpine of her back, and a dram of it was ufed as an enema ; by this medicine a kind of drunken delirium was continued ma- ny hours ; and when it ceafed the convulfions did not return $ and the lady continued well many years, except fome Uighter re- lapfes, which were relieved in the fame manner. Mifs H , an accomplifhed young lady, with light eyes and hair, was feized with convulfions of her limbs, with hiccough, and efforts to vomit, more violent than words can exprefs j thefe continued near an hour, and were fucceeded with a cataleptic fpafm of one arm, with the hand applied to her head ; and af- ter about twenty minutes thefe fpalms ceafed, and a talkative reverie fupervened for near an hour, from which no violence, which it was proper to ufe, could awaken her. Thefe periods of convulfions, firft of the mufcles, and then of the ideas, re- turned twice a day for feveral weeks ; and were at length re- moved by great dofes of opium, after a great variety of other medicines and applications had been in vain experienced. This lady was fubjeci: to frequent relapfes, once or twice a year for many years, and was as frequently relieved by the fame method. Mifs W , an elegant young lady, with black eyes and hair, had fometimes a violent pain of her fide, at other times a moft painful ftrangury, which were every day fucceeded by de- lirium ; which gave a temporary relief to the painful fpafms. After the vain exhibition of variety of medicines and applica- tions by different phyficians, for more than a twelvemonth, (he was directed to take forae dofes of opium, which were gradually increafed, by which a drunken delirium was kept up for a day or two, and the pains prevented from returning. A fleih diet, with a little^ wine or beer, inftead of the low regimen me had previouily ufed, in a few weeks completely eftablifhed her health % which, except a~few relapfes, has continued for many years. 9. Laflly, as we advance in life all the parks of the body be- Vojl. L D Ijcorrie 1 8 : MOTIONS OF Sect. III. 6. r, come more rigid, are rendered lefs fufceptible of new habits of motion, though they retain thofe that were before eftabliihed. This is fenfibly obfei ved by thofe who apply themfelres late in life to mufic, fencing, or any of the mechanic arts. In the fame manner many elderly people retain the ideas they had learned early in life, but find great difficulty in acquiring new trains of memory ; infcmuch that in extreme old age we frequently fee a forgetfulnefs of the bufinefs of yefterday, and at the fame time a circumftantial remembrance of the amufements of their youth; till at length the ideas of recollection and activity of the body gradually ceafe together, — fuch is the condition of humanity ! — and nothing remains but the vital motions and fenfations. VI. i. In oppofition to this doctrine of the production of Our ideas, it may be afked, if fome of our ideas, like other ani- mal motions, are voluntary, why can we not invent new ones, fhat have not been received by perception ? The anfwer will be better underftood after having perufed the fucceeding fection, where it will be explained, that the mufcular morions likewife are originally excited by the ftimulus of bodies external to the moving organ ; and that the will has only the power of repeat- ing the motions thus excited. 1. Another objector may afk, Can the motion of an organ of fenfe referable an odour or a colour ? To which I can only an- fwer, that it has not been demonftrated that any of our ideas re- ferable the objects that excite them ; it has generally been be- lieved that they do not ; but this fhall be difculled at large in Sect. XIV. ; 3. There is another objection that at firft view would feem lefseafy to furmount. After the amputation of afoot or a finger, it has frequently happened, that an injury being offered to the flump of the amputated limb, whether from cold air, too great preiTure, or other accidents, the patient has com- plained of a fenfation cf pain in the foot or finger, that was cut off. Does not this evince that all our ideas are excited in the brain, and not in the organs of fenfe ? This objection is anfwered, by obferving that our ideas of the fhape, place, and folidity of cur limbs, are acquired by our organs of touch and of fight, which are fituated in our fingers and eyes, and not by itions in the limb itfelf: In this cafe the pain or fenfation, which formerly has arifen in (he foot or toes, and been propagated along the nerves to the central part cf the fen fori urn, was at the fame time^ccompanied ,h a vifible idea 1 \ fhape and place, and with a tangible idity of the effected limb : now }vhen thefe nerves d by any injury done to the remaining ump s^1 Sect. III. 6. 4. THE RETINA. iq flump with a fimilar degree or kind of pain, the ideas of the ihape, place, or folidity of the loft limb, return by affochtion ; as thefe ideas belong to the organs of fight and touch, on which they were firft excited. 4. If you wonder what organs of fenfe can be excited into motion, when you call up the ideas of wifdom or benevolence, which Mr. Locke has termed abftracted ideas ; I afk you by what organs of fenfe you firft became acquainted with thefe ideas ? And the anfwer will be reciprocal ; for it is certain that all our ideas were originally acquired by our organs of fenfe -? for whatever excites our perception rnuft be external to the or- gan that perceives it, and we have no other inlets to knowledge but by our perceptions : as will be further explained in Section XIV. and XV. on the Productions and ClaiTes of ideas. VII. If our recollection or imagination be not a repetition of animal movements, I afk, in my turn, What is it ? You tell me it confifts of images or pictures of things. Where is this ex- tenfive canvas hung up ? or where are the numerous receptacles in which thofe are depofited ? or to what elfe in the animal fyftem have they any fimilitude ? That pleafing picture of objects, reprefented in miniature on the retina of the eye, feems to have given rife to this illufive or- atory ! It was forgot that this representation belongs rather to the laws of light, than to thofe of life ; and may with equal ele- gance be feen in the camera obfcura as in the eye ; and that the picture vanifhes for ever, when the object is withdrawn. s;ect. 20 ANIMAL CAUSATION. Sect. IV. SECT. IV. LAWS OF ANIMAL CAUCATION. I. The fibres, which conftitute the mufcles and organs of fenfe, pofTefs a power of contraction. The circumftances at- tending the exertion of this power of contraction conftitute the laws of animal motion, as the circumftances attending the exertion of the power of attraction conftitute the laws of motion of inanimate matter. II. The fpirit of animation is the immediate caufe of the contraction of animal fibres, it refides in the brain and nerves, and is liable to general or partial diminution or accumulation. III. The ftimulus of bodies external to the moving organ is the remote caufe of the original contractions of animal fibres. IV. A certain quantity of ftimulus produces irritation, which is an exertion of the fpirit of animation exciting the fibres into contraction. V. A certain quantity of contraction of animal fibres, if it be perceived at all, produces pleafure ; a greater or lefs quantity of contraction, if it be perceived at all, produces pain ; thefe con- ftitute fenfation. VI. A certain quantity of fenfation produces defire or aver- fion ; thefe conftitute volition. VII. All animal motions which have occurred at the fame time, or in immediate fucceflion, become fo connected, that when one of them is reproduced, the other has a tendency to accompany or fucceed it. When fibrous contractions fucceed or accompany other fibrous contractions, the connexion is term- ed afibciation ; when fibrous contractions fucceed fenforial mo- tions, the connexion is termed caufation j when fibrous and fen- foriarl motions reciprocally introduce each other, it is termed catenation of animal motions. All thefe connexions are faid to be produced by habit, that is, by frequent repetition. Thefe laws of animal caufation will be evinced by numerous facts, which occur in our daily exertions ; and will afterwards be em- ployed to explain the more recondite phenomena of the produc- n, growth, difeafes, and decay of the animal fyftem. SECT. Sect. V. i. SENSORIAL FACULTIES. 21 SECT. V. OF THE FOUR FACULTIES OR MOTIONS OF THE SENSCRIUM. I. Four fenforial powers. 2. Irritation, fen/at ion, volition, ajfoci- ation defined. 3. Senforial motions difiingufhed from fibrous mo- tions. 1. The fpirit of animation has four different modes of ac- tion, or in other words the animal fenforium poifeiTes four dif- ferent faculties, which are oecafionally exerted, and caufe all the contractions of the fibrous parts of the body. Thefe are the faculty of caufing fibrous contractions in confequence of the irritations excited by external bodies, in confequence of the fenfations of pleafure or pain, in confequence of volition, and in confequence of the aflbciations of fjftppus contractions with oth- er fibrous contractions, which precede or accompany them. Thefe four faculties of the fenforium during their inactive ftate are termed irritability, fenfibility, voluntarity, and afibciability ; in their active ftate they are termed as above, irritation, fenfa- tion, volkion, aflbciation. 2. Irritation is an exertion, or change of fome extreme part of the fenforium refiding in the mufcles or organs of fenfe, in confequence of the appulfes of external bodies. Sensation is an exertion or change of the central parts of the fenforium, or of the whole of it, beginning at fome of thofe ex- treme parts of it, which refide in the mufcles or organs of fenfe. Volition is an exertion or change of the central parts of the fenforium, or of the whole of it, terminating in fome of thofe ex- treme parts of it, which refide in the mufcles or organs of fenfe. Association is an exertion or change of fome extreme part of the fenforium refiding in the mufcles or organs of fenfe, in confequence of fome antecedent or attendant fibrous contrac- tions. 3. Thefe four faculties of the animal fenforium may at the time of their exertions be termed motions without impropriety of language ; for we cannot pafs from a ftate of infenfibility or inaction to a ftate of fenfibility or of exertion without fome change of the fenforium, and every change includes motion. We {hall therefore fometimes term the above defcribed faculties fenfo rial motions to diftinguifh them from fibrous motions ; which latter exprcflion includes the motions of the mufcles and organs of fenfe. The active motions of the fibres, whether thofe of the mufcles ^. 22 SENSORIAL FACULTIES. Sect. V. 3. or organs of fenfe, are probably fimple contractions ; the fibres being again elongated by antagonift mufcles, by circulating fluids, or fometimes by elaftic ligaments, as in the necks of quadrupeds. The fenforial motions, which conftitute the fen- lations of pleafure or pain, and which conftitute volition, and which caufe the fibrous contractions in confequence of irritation or of aflbciation, are not here fuppofed to be fluctuations or re- fluctuations of the fpirit of animation 5 nor are they fuppofed to be vibrations or revibrations, nor condenfations or equilibra* tions of it i but to be changes or motions of it peculiar to life. ot SECT. Sect. VI. i. i. FIBROUS CONTRACTIONS. n SECT. VI. OF THE FOUR CLASSES OF FIBROUS MOTIONS. I. Origin of fibrous contractions* II. Diftributien of them into four clajfes, irritative motions, fenfitiie motions, voluntary motions, and officiate motions, defined. 1. All the fibrous contractions of animal bodies originate from the fenforium, and refolve themfelves into four clafTes, cor- refpondent with the four powers or motions of the fenforium above defcribed, and from which they have their caufation. i. Thefe fibrous contractions were originally caufed by the irritations excited by objects, which are external to the moving organ. As the pulfations of the heart are owing to the irrita- tions excited by the ftimulus of the blood ; and the ideas of per- ception are owing to the irritations excited by external bodies. 2. But as painful or pleafurable fenfations frequently accom- panied thofe irritations, by habit thefe fibrous contractions be- came caufable by the fenfations, and the irritations ceafed to be neceflary to their production. As the fecretion of tears in grief is caufed by the fenfation of pain ; and the ideas of imagina- tion, as in dreams or delirium, are excited by the pleafure or pain, with which they were formerly accompanied. 3. But as the efforts of the will frequently accompanied thefe painful or pleafurable fenfations, by habit the fibrous con- tractions became caufable by volition ; and both the irritations and fenfations ceafed to be neceflary to their production. As the deliberate locomotions of the body, and the ideas of recol- lection, as when we will to repeat the alphabet backwards. 4. But as many of thefe fibrous contractions frequently ac- companied other fibrous contractions, by habit they became caufable by their aflbciations with them ; and the irritations, fenfations, and volition, ceafed to be neceflary to their produc- tion. As the actions of the mufcles of the lower limbs in fen- cing are aflbciated with thofe of the arms"*, and the ideas of fug- geftion are afibcicrted with other ideas, which precede or accom- pany them ; as in repeating carelefsly the alphabet in its ufual order after having began it. II. We (hall give the following names to thefe four clafles of fibrous motions, and fubjoin their definitions. 1. Irritative motions. That exertion or change of the fenfo- rium, which is caufed by the appulfes of external bodies, either fimply fubfides, or is fucceeded by fenf*tiop, or it produces * fibrous 54 FIBROUS CONTRACTIONS. . Sect. VI. 2. 2. fibrous motions ; it is termed irritation, and irritative motions are thofe contractions of the mufcular fibres, or of the organs of fenfe, that are immediately confequent to this exertion or ohangeofthe fenforium. 2. Senfitive motions. That exertion or change of the fenfo- rium, which conftitutes pleafure or pain, either fimply fubfides, or is fuccecded by volition, or it produces fibrous motions *, it is termed fenfation, and the fenfitive motions are thofe contrac- tions of the mufcular fibres, or of the organs of fenfe, that are immediately confequent to this exertion or change of the fenfo- rium. 3. Voluntary motions. That exertion or change of the fen- forium, which conftitutes defire or averfion, either fimply fub- fidc,, or is fucceeded by fibrous motions ; it is then termed vo- lition, and voluntary motions are thofe contractions of the muf- cular fibres, or of the organs of fenfe, that are immediately con- fequent to this exertion or change of the fenforium. 4. Aflbciate motions. That exertion or change of the fen- forium, which accompanies fibrous motions, either fimply fub- fides, or is fucceeded by fenfation or volition, or it produces other fibrous motions ; it is then termed aflbciation, and the af- fociate motions are thofe contractions of the mufcular fibres, or of the organs of fenfe, that are immediately coufequent to this exertion or change of the fenforium. % • 1 SECT. I Sect. VII. i. i. IRRITATIVE MOTIONS. 25 SECT. VII. OF IRRITATIVE MOTIONS. I. I. Some mufcular motions are excited by perpetual irritations. 2 Others more frequently by fenfations. 3. Others by volition. Cafe of involuntary f retchings in paralytic limbs. 4. Some fen- fual motions are excited by perpetual irritations. 5. Others more . frequently by fenfation or volition. II. I. Mufcular motions ex- cited by perpetual irritations occafwnally become obedient to fenfation and to volition. 2. And the fenfual motions. III. 1. Other muf- cular motions are affociated with the irritative ones. 1. And other ideas with irritative ones. Of letters , language, hieroglyphics. Irritative ideas exijl without our attention to them. I. r. M. any of our mufcular motions are excited by perpet- ual irritations, as thofe of the heart and arterial fyftem by the circumfluent blood. Many other of them are excited by inter- mitted irritations, as thofe of the flomach and bowels by the ali- ment we fwallow ; of the bile-ducts by the bile ; of the kid- neys, pancreas, and many other glands, by the peculiar fluids they feparate from the blood ; and thofe of the lacteal and oth- er abforbent vefTels by the chyle, lymph, and moiflure of the at- mofphere. Thefe motions are accelerated or retarded, as their correfpondent irritations are increafed or diminifhed, without, our attention or confcioumefs, in the fame manner as the vari- ous fecretions of, fruit, gum, refin, wax, and honey, are produ- ced in the vegetable world, and as the juices of the earrh and the moiilure of the atmofphere are abforbed by their roots and foliage. 2. Other mufcular motions, that are mod frequently con- nected with our fenfations, as thofe of the fphincfers of the bladder and anus, and the mufculi ereclores penis, were origin- ally excited into motion by irritation, for young children make water, and have other evacuations without attention to thefe cir- cumflances ; " et primis etiam ab incunabulis tenduntur fispi- us puerorum penes, amore nondum expergefael:o." So the nip- ples of young women are liable to become turgid by irritation, long before they are in a iituation to be excited by the pleafure of giving milk to the iips of a child. 3. The ^tontraclicns of the larger mufclss of our boli.-s, tha,t are molt frequently connected with volition, were originally ex- cited into action by internal irritations : as appears from trie: ^•retching or yawning of all anim?." :r long fieep. In trie Vol. L * E nni»g *< IRRTTATIVE Sect. VIL r. 4, beginning of fomc fevers this irritation of the mufcles produces perpetual ftretching and yawning •, in other periods of fever an univerial reftlefTnefs arifes from the fame caufe, the patient changing the attitude of his body every minute. The repeated ftruggles of the fcetus in the uterus mult be owing to this inter- nal irritation : for the foetus can have no other inducement to move its limbs but the tsedium or irkfomenefs of a continued pofture. The fcllowing cafe evinces, that the motions of ftretching the limbs after a continued attitude are not alwavs owine to the power of the will. Mr. Dean, a mafon, of Auftry, in Leicefterfhire, had the fpine of the third vertebra of the back enlarged ; in fome weeks his lower extremities became feeble, 2nd at length quite paralytic : neither the pain of blifters, the heat of fomentations, nor the utmoft efforts of the will could produce the leaft motion in thefe limbs ; yet twice or thrice a day for many months his feet, legs, and thighs, were arretted for many minutes with forcible flretchings, attended with the fenfation of fatigue ; and he at length recovered the ufe of his limbs, though the fpine continued protuberant. The fame cir- cumftance is frequently {ten in a lefs degree in the common hemiplegia ; and when this happens, I have believed repeated and ftrong (Locks of electricity to have been of great advantage. 4. In like manner the various organs of fenfe are originally excited into motion by various external ltimuli adapted to this purpofe, which motions are termed perceptions or ideas ; and many of thefe motions during our waking hours are excited by perpetual irritation, as thole of the organs of hearing and of touch. The former by the conftant low indiitindl; noifes that murmur around us, and the latter by the weight of our bodies on the parts which fupport them 5 and by the unceafing varia- tions of the heat, moiilure, and preiTure of the atmofphere ; and thefe fenfual motions, ■ precifely as the mufcular one above mentioned, obey their correfpondent irritations without our at- tention cr confeioufnefs. 5. Other daffes of our ideas are more frequently excited by our fenfations of pleafure or pain, and others by volition : but that thefe have all been originally excited by ftimuli from exter- nal objects, and only vary in their combinations or feparations, ha$ been fully evinced by Mr. Locke : and are by him termed the ideas of perception in contradiftinction to thofe, which he calls the ideas of reflection. A II. 1. Thefe mufcular motions, that are e::cited vy perpetual ritation, are-ncverthelefs occafionaiiy excitable by the feniations afure ox pain, or by volition ; as appears by the palpita- tion Sect. VII. 2. 2. MOTIONS. 27 tion of the heart from fear, the increafed fecretion of faliva at the fight of agreeable food, and the glow on the fkin of thofe who are afhamed. There is an in fiance told in the Phiiofophi- cal Tranfactions of a man, who could for a. time flop the mo- tion of his heart when he pleafed ; and Mr. D. has often told me, he could fo far increafe the periftaitic motion of his bowels by voluntary efforts, as to produce an evacuation by ftool at any time in half an hour. 2. In like manner the fenfual motions, or ideas, that are ex- cited by perpetual irritation, are neverthelefs occafionally exci- ted by fenfation or volition ; as in the night, when we liften under the influence of fear, or from voluntary attention, the motions excited in the organ of hearing by the whiipering oi the air in our room, the pulfation of our own arteries, or the faint beating of a dntant watch, become objects of perception. III. 1. Innumerable trains or tribes of other motions are af- fociated with thefe mufcular motions which are excited by irri- tation ; as by the fiimulus of the blood in the right chamber of the heart, the lungs are induced to expand themfelves ', and the pectoral and intercoflal mufcles, and the diaphragm, act at the fame time by their aflbciations with them. And when the pha- rinx is irritated by agreeable food, the mufcles of deglutition are brought into action by afibciation. Thus when a greater light falls on the eye, the iris is brought into action without our at- tention, and the ciliary procefs, when the focus is formed be- fore or behind the retina, by their affociations with the increaf- ed irritative motions of the organ of vifion. Many common actions of life are produced in a fimilar manner. If a fly fettle on my forehead, whilfl I am intent on my prefent occupation, I dillodge it with my finger, without exciting my attention or breaking the train of my ideas. 2. In like manner the irritative ideas fuggeft to us many oth- er trains or tribes of ideas that are aflbciated with them. On this kind of connexion, language, letters, hieroglyphics, and ev- ery kind of fymbol, depend. The fymbols themfelves produce irritative ideas, or fenfual motions, which we do not attend to ; and other ideas, that are fucceeded by fenfation, are excited by their afibciation with them. And as thefe irritative ideas make up a part of the chain of our waking thoughts, introducing oth- er ideas that engage our attention, though themfelves are unat- tended to, we find it very difficult to investigate by what fteps many of oumhourly trains of ideas gain their admittance. It may appear paradoxical, that ideas can exifc, and not be at- tended to ; but all our perceptions are ideas excited by irrita- tion, and fucceeded by fenfation. Now when thefe ideas exci- ted £8 IRRITATIVE MOTIONS. Sect. VII. 3. 2. ted by irritation give us neither pleafure nor pain, we ceafe to attend to them. Thus whilft I am walking through that grove before my window, I do not run againit the trees or the benches, though my thoughts are ftrcnuoufly exerted on fome other ob- ject. This leads us to a diftinct knowledge of irritative ideas, for the idea of the tree or bench, which I avoid, exifts on my lina, and induces by aflbciation the action of certain locomo- tive mufcles ; though neither itfclf nor the aclions of thofe muf- clcs engage my attention. Thus whilft we are converting on this fubjecl:, the tone, note, and articulation of every individual word forms its correfpondent irritative idea on the organ of hearing ; but we only attend to the afTociated ideas, that are attached by habit to thefe irritative ones, and are fucceeded by fenfation ; thus when we read the words " printing-press" we do not attend to the fhape, fize, or exiftence of the letters which compofe thefe words, though each of them excites a correfpondent irritative motion of our organ of vifion, but they introduce by aflbciation our idea of the moll ufeful of modern inventions ; the capacious refervoir of human knowledge, whofe branching flreams diffufe fciences, arts, and, morality, through all nations and all ages. ; SECT. ,£ect. VIII. i.i. SENSITIVE MOTIONS. ^ SECT. VIII. OF SENSITIVE MOTIONS. I. I . Serf five mufcular motions were originally excited into action by irritation, 2. Andfenfitive fenfual motions, ideas of imagina- tion, dreams. II. I. Senjitive mufcular motions are occafonally obedient to 'volition. 2. And fenfttive fenfual motions. III. I. Other mufcular motions are officiated with the fenfitive ones, 2- And other fenfual motions. 1. I. Many of the motions of our mufcles, that are excited into action by irritation, are at the fame time accompanied with painful or pleafurable fen fat ions ; and at length become by habit caufable by the fenfations. Thus the motions of the fphincters of the bladder and anus were originally excited into action by irritation ; for young children give no attention to thefe evacuations ; but as foon as they become fenfible of the inconvenience of obeying thefe irritations, they fuffer the water or excrement to accumulate, till it difagreeably affects them 5 and the action of thofe fphincters is then in confequence of this difagfeeable fenfation. So the fecretion of faliva, which in young children is copioufly produced by irritation, and drops from their mouths, is frequently attended with the agreeable fenfation produced by the maftication of tafteful food ; till at length the fight of fuch food to a hungry perfqn excites into action thefe falival glands ; as is (sen in the Havering of hungry dogs. The motions of thofe mufcles, which are affected by lafcivi- ous ideas, and thofe which are exerted in fmiling, weeping, flarting from fear, and winking at the approach of clanger to the eye, and at times the actions of every large mufcle of the body become caufable by our fenfations. And all thefe motions are performed with ilrength and velocity in proportion to the energy of the fenfation that excites them, and the quantity of fenforial power. 2. Many of the motions of our organs of fenfe, or ideas, that were originally excited into action by irritation, become in like manner more frequently caufable by our fenfations of pleafure or pain. Thefe motions are then termed the ideas of imagina- tion, and make up all the fcenery and tranfactions of our dreams. Thus when any painful or pleafurable fenfations pof- fefs us, as of love, anger, fear ; whether in our fleep or waking hours, the ideas, that have been formerly excited by the objects of $5 SENSITIVE MOTIONS. Sect. VIII. 2. ri of thefe fenfations, now vividly recur before us by their con- nexion with thefe fenfations themfelves. So the fair fmiling virgin, that excited your love by her prefence, whenever that fenfation recurs, rifes before you in imagination 5 and that with all the pleafmg circumftances, that had before engaged your at- tention. And in fleep, when you dream under the influence of fear, all the robbers, fires, and precipices, that you formerly have feen or heard of, arife before you with terrible vivacity. All thefe fenfual motions, like the mufcular ones above mentioned, are performed with ftrength and velocity in proportion to the energy of the fenfation of pleafure or pain, which excites them, and the quantity of fenforial power. II. 1. Many of thefe mufcular motions above defcribed, that are moll frequently excited by our fenfations, are neverthelefs occafionally caufable by volition ; for we can fmile or frown fpontaneoufly, can make water before the quantity or acrimony of the urine produces a difagreeable fenfation, and can volunta- rily mafticate a naufeous drug, or fwallow a bitter draught, though our fenfation would ftrongly diffuade us. 2. In like manner the fenfual motions, or ideas, that are molt frequently excited by our fenfations, are neverthelefs occafion- ally caufable by volition, as we can fpontaneoully call up our laft night's dream before us, tracing it induftriouily ftep by ftep through all its variety of fcenery and tranfaction ; or can volun- tarily examine or repeat the ideas, that have been excited by our difgult or admiration. III. 1. Innumerable trains or tribes of motions are afibciated with thefe fenfitive mufcular motions above mentioned ; as when a drop of water falling into the wind-pipe difagreeably affects tliQ air-vefiels cf the lungs, they are excited into violent action ; and with thefe fenfitive motions are afibciated the actions of the pectoral and intercoftal mufcles, and the diaphragm ; till by their united and repeated fuccefhons the drop is returned through the larinx. The fame occurs when any thing difagree- ably affects the noftrils, or the ftomach, or the uterus ; variety of mufcles are excited by affociation into forcible action, not to be fupprefied by the utmoft efforts of the will ; as in fneezing, vomiting, and parturition. 2. In like manner with thefe fenfitive fenfual motions, or ideas of imagination, are affociated many other trains or tribes of ideas, which by fomc writers of metaphyfics have been claffed under the terms of refemblance, caufatiouj and contiguity ; and wil more fully treated of hereafter. SECT. Sect. IX. i. i. VOLUNTARY MOTIONS. 3 1 SECT. IX. OF VOLUNTARY MOTIONS. L 1 . Voluntary mufcular motions are originally excited by irritations. 2. And voluntary ideas, Ofreafon. II. I. Voluntary mufcular motions are occafionally caufable by fenfat'tons. 2. And voluntary ideas. III. I. Voluntary mufcular motions are occafionally obe- dient to irritations. 2. And voluntary ideas. IV. I. Volun* tary mufcular motions are officiated with other mufcular motions. 2. And voluntary ideas. "When pleafure or pain afFecl: the animal fyftem, many of its motions both mufcular and fenfual are brought into action ; as was {hewn in the preceding feclion, and were called fenfitivc motions. The general tendency of thefe motions is to arreft and to poffefs the pleafure, or to di/lodge or avoid the pain : but if this cannot immediately be accomplished, defire or averfion is produced, and the motions in confequence of this new faculty of the fenforium are called voluntary. 1. 1. Thofe mufcles of the body that are attached to bones, have in general their principal connexions with volition, as I move my pen or raife my body. Thefe motions were original- ly excited by irritation, as was explained in the fection on that fubject, afterwards the fenfations of pleafure or pain, that accom- panied the motions thus excited, induced a repetition of them ; and at length many of them were voluntarily praclifed in fuc- ceilion or in combination for the common purpofes of life, as in learning to walk, or to fpeak ; and are performed with ftrength and velocity in proportion to the energy of the volition, that excites them, and the quantity of fenforiai power. 2. Another great ciafs of voluntary motions confifts of the ideas of recollection. We will to repeat a certain train of ideas, as of the alphabet backwards ; and if any ideas that do not be- long to this intended train, intrude themfelves by other connex- ions, we will to reject them, and voluntarily periift in the deter- mined train. So at my approach to a houfe which I have but once viCitedy and that at the diftance of many months, I will to recollect the names of the numerous family I expert to fee there, and I do recollect them. On this voluntary recollection of ideas our faculty of reafon depends, as it enables us to acquire an idea of the diflimiutuda of any two ideas. Thus if you voluntarily produce the idea of a right-angled triangle, and then of a fquare \ and after having excited 32 VOLUNTARY MOTIONS. Sect. IX 2. u excited thefe ideas repeatedly, you excite the idea of their differ- ence, which is that of another right-angled triangle inverted over the former ; you are faid to reafon upon this fubject, or to compare your ideas. 'Thefe ideas of recollection, like the mufcular motions above mentioned, were originally excited by the irritation of external bodies, and were termed ideas of perception : afterwards the pleafure cr pain, that accompanied thefe motions, induced a rep- lion of them in the abfence of the external body, by which they were firft excited ; and then they were termed ideas of imagination. At length they become voluntarily practiced in fucceffion or in combination for the common purpofes of life ; a~. when we make ourfelves mafters of the hiftory of mankind, or of the Sciences they have inveftigated ; and are then called ideas of recollection ; and are performed with Strength and velocity in proportion to the energy of the volition that excites them, and the quantity of fenforial power. II. 1. The mufcular motions above defcribed, that are mod frequently obedient to the will, are neverthelefs occasionally caufable by painful or pleafurable fenfation, as in the flarting from fear, and the contraction of the calf of the leg in the cramp. 2. In like manner the fenfual motions, or ideas, that are mod frequently connected with volition, are neverthelefs occasionally caufable by painful or pleafurable fenfation. As the histories of men, or the defcription of places, which we have voluntarily taken pains to remember, fometimes occur to us in our dreams. III. I. The mufcular motions that are generally fubfervient to volition, are alio occasionally caufable by irritation, as in ftrctchlng the limbs after fleep, and yawning. In this manner a contraction of the arm is produced by palling the electric fluid from the Leyden phial along its mufcles ; and that even though the limb is paralytic. The fudden motion of the arm produces a difagreeable fenfation in the joint, but the mufcles feern to be brought into action fimply by irritation. 2. The ideas, that are generally fubfervient to the will, are in like manner occaiionally excited by irritation ; as when we view again an object, we have before well ftudied, and often recc 1. IV. 1. Innumerable trains or tribes of motions are affociated with thefe voluntary mufcular motions above mentioned ; as when I will to extend my arm to a dittant object, fome other trr re brought into action, and preferve the balance of my body. And when I v. ifh to perform any fieady exertion, as in threading Sect. IX. 4. 2- VOLUNTARY MOTIONS, 33 threading a needle, or chopping with an ax, the pectoral mufcles are at the fame time brought into action to preferve the trunk of the body motionlefs, and we ceafe to refpire for a time. 2. In like manner the voluntary fenfual motions, or ideas of recollection, are aflbciated with many other trains or tribes of ideas. As when I voluntarily recollect a gothic window, that I faw fome time ago, the whole front of the cathedral occurs to me at the feme time. Vojt, L F SECT. 34 ASSOCIATE Sect. X. i. i. SECT. X. OF ASSOCIATE MOTIONS. I. I. Many mufcular motions excited by irritations in trains of tribes become affiociated. 2. And many ideas. II. i. Many fenfiiive mufcular motions become officiated* 2. And many fen- Jitive ideas. III. I . Many voluntary mufcular motions become officiated. 2. And then become obedient to fenfation or irritation* 3. And many voluntary ideas become officiated. All the fibrous motions, whether mufcular or fenfual, which are frequently brought into action together, either in combined tribes, or in fuccelfivc trains, become fo connected by habit, that when one of them is reproduced the others have a tendency to fucceed or accompany it. 1. 1. Many of our mufcular motions were originally excited in fucceflive trains, as the contractions of the auricles and of the ventricles of the heart •, and others in combined tribe?, as the various divifions of the mufcles which compofe the calf of the leg, which were originally irritated into fynchronous action by the tedium or irkfomenefs of a continued pofture. By fre- quent repetitions thefe motions acquire aflbciations, which con- tinue during our lives, and even after the deftruction of the greateft part of the fenforium ; for the heart of a viper or frog will continue to pulfate long after it is taken from the body ; and when it has entirely ceafed to move, if any part of it is goaded with a pin, the whole heart will again renew its pulfa- tions. This kind of connexion we (hall term irritative aflbcia- tion, to diftinguim it from fenfitive and voluntary aflbciations. 2. In like manner many of our ideas are originally excited in tribes ; as all the objects of fight, after we become fo well ac- quainted with the laws of vifion, as to diitinguifh figure and dis- tance as well as colour ; or in trains, as while we pafs along the objects that furround us. The tribes thus received by irritation become affbeiated by habit, and have been termed complex ideas by the writers of metaphyfics, as this book, or that orange. The trains have received no particular name, but thefe are alike af- fociations of ideas, and frequently continue during our lives. So the talte of a pine-apple, though we eat it blindfold, recalls the colour and fnape of it ; and we can fcarcely think on folidi- ty without figure. II. 1. Ey the various efforts of our fenfations to acquire or •id their objects, many mufcles are daily brought into fuccef- five Sect. X. 2. 2. MOTIONS, 35 five or fynchronous alliens ; thefe become a/Tociated by habit, and are then excited together with great facility, and in many inftances gain indifTolubie connexions. So the play of puppies and kittens is a reprefentation of their mode of fighting or of taking their prey ; and the motions of the mufcles necefTary for thofe purpofes become afTociated by habit, and gain a great adroitnefs of action by thefe early repetitions ; fo the motions of the abdominal mufcles, which were originally brought into concurrent action with the protrufive motion of the rectum or bladder by fenfation, become fo conjoined with them by habit, that they not only eafily obey thefe fenfations occafioned by the ftimulus of the excrement and urine, but are brought into vio- lent and unreftrainable action in the ftrangury and tenefmus. This kind of connexion we mail term fenfitive afTociation. 2. So many of our ideas, that have been excited together or in fucceffioxi by our fenfations, gain fynchronous or fuccefhve afTociarions, that are fometimes indifTolubie but with life. Hence the idea of an inhuman or difhonourable action perpetually calls up before us the idea of the wretch that was guilty of it. And hence thofe unconquerable antipathies are formed, which feme people have to the fight of peculiar kinds of food, of which in their infancy they have eaten to excefs or by conftraint. III. 1. In learning any mechanic art, as mufic, dancing, or the ufe of the fword, we teach many of our mufcles to act to- gether or in fucceffion by repeated voluntary efforts ; which by habit become formed into tribes or trains of afTociation, and ferve all our purpofes v/ith great facility, and in fome inftances acquire an indifTolubie union. Thefe motions are gradually formed into a habit of acting together by a multitude of repeti- tions, whilft they are yet feparately caufable by the will, as is evident from the long time that is taken up by children in learn- ing to walk and to fpeak ; and is experienced by every one> when he firft attempts to Ikate upon the ice or to fwim : thefe we (hall term voluntary alTociations. 2. All thefe mufcular movements, when they are thus afToci- ated into tribes or trains, become afterwards not only obedient to volition, but to the fenfations and irritations ; and the fame movement compofes a part of many* different tribes or trains of motion. Thus a flngle mufcle, when it acts in con fort with its neighbours on one fide, afTifts to move the limb in one direction ; and in another, when it acts with thofe in its neighbourhood on the other fide ; and in other directions, when it acts feparately or jointly with thofe that lie immediately under or above it ; and all thefe with equal facility after their afibciations have been well eftablifhed, The 36 ASSOCIATE MOTIONS. Sect. X. 3. 3, The facility, with which each mufcle changes from one aflo- ciated tribe to another, and that either backwards or forwards, is well obfervable in the mufcles of the arm in moving the wind- lafs of an air-pump ; and the flownefs of thofe mufcular move- ments, that have not been affociated by habit, may be experi- enced by any one, who (hall attempt to faw the air quick per- pendicularly with one hand, and horizontally with the other at the fame time. 3. In learning every kind of fcience we voluntarily aflbciate many tribes and trains of ideas, which afterwards are ready for all the purpofes either of volition, fenfation, or irritation ; and in feme inftances acquire indiffoluble habits of acting together, fo as to affect, our reafoning, and influence our actions. Hence the neceffity of a good education. Thefe aflbciate ideas are gradually formed into habits of act- ing together by frequent repetition, while they are yet feparately obedient to tht will ; as is evident from the difficulty we experi- ence in gaining fo exact an idea of the front of St. Paul's church, as to be able to delineate it with accuracy, or in recollecting a poem of a few pages. And thefe ideas, thus affociated into tribes, not only make up the parts of the trains of volition, fenfation, and irritation ; but the fame idea compofes a part of many different tribes and trains of ideas. So the fimple idea of whitenefs compofes a part of the complex idea of fnow, milk, ivory ; and the complex idea of the letter A compofes a part of the feveral affociated trains of ideas that make up the variety of words, into which this letter enters. The numerous trains of thefe affociated ideas are divided by Mr. Hume into three claffes, which he has termed contiguity, eaufation, and refemblance. Nor mould we wonder to find them thus connected together, fince it is the bufinefs of our lives to difpofe them into thefe three claffes 5 and we become valuable to ourfelves and our friends, as we fucceed in it. Thofe who have combined an extenfive clafs of ideas by the contiguity of time or place, are men learned in the hiflory of mankind, and of the fciences they have cultivated. Thofe who have connect- ed a great clafs of ideas of refemblances, poffefs the fource of the ornaments of poetry a, elaflicity. Spirit of life is not electric ether. Galvams experiments. 2. Contraction of a fibre. 3. Relaxation fuc- ceeds. 4. Succeffive contractions , with intervals. Quick pnlfe ■ from debility , from paucity of blood. Weak contractions perform- ed in lefs time, and with fhorter intervals. 5. Lafil filia- tion of the fibres continues after contraclion. 6. Contraclion greater them ufual induces pleafure or pain. 7. Mobility of the fibres uniform. Quantity oj fenforial power fiutluates. Confii- tutes excitability. IL Of fenforial exertion. 1. Animal motion includes ftimulus, fenforial power, and contractile fibres. The fen- forial faculties act feparately or conjointly. Stimulus of four kinds. Strength and weaknefs defined. Senforial power perpetually ex- haufied and renewed. Weaknefs from defecl offiimulus. From defect of fenforial power, the direct and indirect debility of Dr. Brown. Why we become warm in Buxton bath after a time, and fee well after a time in a darkifh room. Fibres may act violently, or with their whole force, and yet feebly. Great exertion in in- flammation explained. Great mufcular force of fome infane peo- ple. 1. Qccafional accumulation of fenforial power in mufcles fub~ Ject to confiant flimulus . In animals jleeping in winter. In eggs, feeds 9 fcirrhous tumours, tendons, bones. 3. Great exertion in- troduces pleafure or pain. Inflammation. Libration of the fyf- iem between torpor and activity. Fever-fits. 4. Defire and a- verfion introduced. Excefs of volition cures fevers. III. Of re- peated ftimulus. I. A flimulus repeated too frequently lofes ef- fect. As opium, wine, grief. Hence old age. Opium and aloes infmalldofes. 2. A flimulus not repeated too frequently does not lofe effect. Perpetual movement of the vital organs. 3. Afilim- ttlus repeated at uniform times produces greater effect. Irrita- tion combined with ajfeiation. 4. A flimulus repeated frequent- ly and uniformly may be withdrawn, and the action of the organ will continue. Hence the bark cures agues ^ and Jlrengthens weak confiitutions. 5 . Defecl offiimulus repeated at certain intervals canjes fever-fits. 6 Stimulus long applied ceafes to acl a fecond time. 7. If a flimulus excites fenfation in an organ not ufua'ly excited into fejifation, inflammation is produced. IV. Of ftimu- lus greater than natural. I. A flimulus greater than natural dimimlhes 44 OF STIMULUS Sect. XII. i. 2. diminifhes the quantity of ' fenforial power in general. 2. In par- ticular organs. 3. Induces the organ into fpafmodic ablions. 4. Induces the antagonifi fibres into action. 5. Induces the organ in- to convulfive or fixed fpafms. 6. Produces paralyfis of the or- gan. V. Of fiimulus lefs than natural. 1. Stimulus lefs than natural occafions accumulation of fenforial power in general. 2. In particular organs ,fiufinng of the face in a frofiy morning. In fibres fubjecl to perpetual fiimulus only, ^lantity of fenforial power inverfely as the fiimulus. 3. Induces pain. As of cold, hunger, head-ach. 4. Induces more feeble- and frequent contrac- tion. As in low fevers. Which are frequently owing to deficien- cy of fenforial power rather than to deficiency of fiimulus. 5. In- verts fuccefifive trains of motion. Inverts ideas. 6. Induces pa- ralyfis and death. VI. Cure of increafed exertion. 1. Nat- ural cure of exhaufiion of fenforial power. 2. Decreafe the irri- tations. Venefeciion. Cold. Abfiinence. 3. Prevent the pre- vious cold fit. Opium. Bark. Warmth. Anger. Surprife. 4. Excite fame other part of the fyfiem. Opium and warm bath relieve pains both from defect and from excefs of fiimulus. 5. s?irfi increafe the fiimulus above, and then decreafe it beneath the natural quantity. VII. Cure of decreafed exertion. 1. Nat- ural cure by accumulation of fenforial power. Ague-fits. Synco- pe. 2- Increafe the fiimulation, by wine, opium, given fo as not to intoxicate. Cheerful ideas. 3. Change the kinds of fiimulus, 4. Stimulate the affociated organs. Blifiers ofufe in heart-burn, and cold extremities. 5. Decreafe the fiimulation for a time, cold bath. 6. Decreafe the fiimulation below natural, and then in- creafe it above natural. Bark after emetics. Opium after vene- feclion. Practice of Sydenham in chlorofis. 7. Prevent unnecef- fary expenditure of fenforial power. Decumbent pofiure,filence, darknefs. Pulfe quickened by rifing out of bed. 8. To the great- efi degree of quiefcence apply the leaf} fiimulus. Other wife pa- ralyfis or inflammation of the organ enfues. Gin, wine, blifiers, defiroy by too great fiimulation in fevers with debility. Intoxica- tion in the fiightefl degree fucceeded by debility. Golden rule for determining the befi degree of fiimulus in low fevers. Another golden rule for ditermming the quantity of fpirit which thofe, who are debilitated by drinking it, ?nayfafely omit. VIII. Conclufion, S^mefiimuli increafe the production cf fenforial power, I. Of fibrous contraction. 1. If two particles of iron lie near each other without mo- tion, and afterwards approach each other ; it is reasonable to conclude that ft>;nething befides tiic iron particles is the caufeof their Sect. XH. i. i. AND EXERTION. 45 their approximation ; this invisible fomething is termed magaet- ifm. In the fame manner, if the particles, which compofe an animal mufcle, do not touch each other in the relaxed State of the mufcle, and are brought into contact during the contraction of the mufcle ; it is reafonable to conclude, that fome other agent is the caufe of this new approximation. For nothing nan ft&i luhere it does not exijl j for to a£l includes to zxijl ; and there- fore the particles of the mufcular fibre (which in its State of re- laxation are fuppofed not to touch) cannot affect each other without the influence of fome intermediate agent ; this agent is here termed the fpirit of animation, or fenforial power, but may with equal propriety be termed the power, which caufes con- traction ; or may be called by any other name, which the reader may choofe to affix to it. The contraction of a mufcular fibre may be compared to the following electric experiment, which is here mentioned not as a philofophical analogy, but as an illuftration or fimile to facil- itate the conception of a difficult fubject. Let twenty very final! Leyden phials properly coated be hung in a row by fine filk threads at a fmall diftance from each other ; let the internal charge of one phial be poiltive, and of the other negative alter- nately, if a communication be made from the internal furface of the firft to the external furface of the lafl in the row, they will all of them inftantly approach each other, and thus fhorten a line that might connect them like a mufcular fibre. See Botanic Garden, P. I. Canto I. 1. 202. note on Gymnotus. The attractions of electricity or of magnetifm do not apply philofophically to the illuftration of the contraction' of animal fibres, fince the force of thofe attractions increafes in fome pro- portion inverfely as the diftance, but in mufcular motion there appears no difference in velocity or Strength during the begin- ning or end of the contraction, but what may be clearly afcribed to the varying mechanic advantage in the approximation of one bone to another. Nor can mufcular motion be aflimilated with greater plaufibility to the attraction of cohefionor elasticity ; for in bending a Steel fpring, as a fmall fword, a lefs force is re- quired to bend it the firft inch than the fecond ; and the fecond than the third ; the particles of fteel on the convex fide of the bent fpring endeavouring to reftore themfelves more powerfully the further they are drawn from each other. See Botanic Gar- den, P. I. addit. Note XVIII. I am aware that this may be explained another way, by fup- poiing the elafticity of the fpring to depend more on the com- preflion of the particles on the concave fide than on the exten- bon of them sn the convex fide j and by fij^pofing the elasticity of 46 OF STIMULUS Sect. XII. i. 2. of the elaftic gum to depend more on the refiftance to the lateral compreffion of its particles than to the longitudinal extenfion of them. Neverthelefs in mufcular contraction, as above observ- ed, there appears no difference in the velocity or force of it at its commencement or at its termination ; from whence we muft conclude that animal contraction is governed by laws of its own, and not by thofe of mechanics, chemiftry, magnetifm, or elec- tricity. On thefe accounts I do not think the experiments conclufive, which were lately publifhed by Galvani, Volta, and others, to (hew a fimilitude between the fpirit of animation, which con- tracts the mufcular fibres, and the electric fluid. Since the electric fluid may act only as a more potent Itirnulus exciting the mufcular fibres into action, and not by fupplying them with a new quantity of the fpirit of life. Thus in a recent hemiple- gia I have frequently obferved, when the patient yawned and ftretched himfelf, that the paralytic limbs moved alfo, though they were totally difobedient to the will. And when he was electrified by palling fhocks from the affected hand to the affect- ed foot, a motion of the paralytic limbs was alfo produced. Now as in the act of yawning the mufcles of the paralytic limbs were excited into action by the flimulus of the irkfomenefs of a con- tinued pofture, and not by any additional quantity of the fpirit of life ; fo we may conclude, that the paffage of the electric flu- id, which produced a fimilar effect, acted only as a flimulus, and not by fupplying any addition of fenforial power. If neverthelefs this theory fhould ever become eltablifhed, a flimulus muft be called an eductor of vital ether ; which flim- ttlus may confift of fenfation or volition, as in the electric eel, as well as in the appulfer> of external bodies ; and by drawing off the charges of viral fluid may occafion the contraction or mo- tions of the mufcular fibres, and organs of fenfe. 2. The immediate effect of the action of the fpirit of anima- tion or fenforial power on the fibrous parts of the body, whether it acts in the mode of irritation, fenfation, volition, or affocia- tion, is a contraction of the animal fibre, according to the fec- ond law of animal caufation. Sect . IV. Thus the flimulus of the blood induces the contraction of the heart ; the agreeable .:e of a (Ira ;v berry produces the contraction of the mufcles of deglutition ; the effort of the will contrails the mufcles, which f e limb", in walking \ and by affociation other mufcles of ' 5 tru ought into contraction to preferve the balance of the L- The fibrous extremities of the organs of fenfe :wn, : he ocular fpectra in Sect III. to fuller fimila* Sect. XII. i. 3. AND EXERTION. 47 fimilar contraction by each of the above modes of excitation ; and by their configurations to conftitute our ideas. 3. After animal fibres have for fome time been excited into contraction, a relaxation fucceeds, even though the exciting caufe continues to act. In refpect to the irritative motions this is exemplified in the periftaltic contractions of the bowels ; which ceafe and are renewed alternately, though the ftimulus of the aliment continues to be uniformly applied ; in the fenfitive motions, as in ftrangury, tenefmus, and parturition, the alter- nate contractions and relaxations of the mufcles exift, though the ftimulus is perpetual. In our voluntary exertions it is expe- rienced, as no one can hang long by the hands, however vehe- mently he wills fo to do j and in the afibciate motions the con- stant change of our attitudes evinces the neceffity of relaxation to thofe mufcles, which have been long in action. This relaxation of a mufcle after its contraction, even though the ftimulus continues to be applied, appears to arife from the expenditure or diminution of the fpirit of animation previoufly refident in the mufcle, according to the fecond law of animal caufation in Sect. IY. In thofe conftitutions, which are termed weak, the fpirit of animation becomes fooner exhaufted, and tremulous motions are produced, as in the hands of infirm peo- ple, when they lift a cup to their mouths. This quicker ex- hauftion of the fpirit of animation is probably owing to a lefs quantity of it refiding in the acting fibres, which therefore more frequently require a fupply from the nerves, which belong to them. 4. If the fenforial power continues to act, whether it acts in the mode of irritation, fenfation, volition, or afFociation, a new contraction of the animal fibre fucceeds after a certain interval ; which interval is of fhorter continuance in weak people than in ftrong ones. This is exemplified in the making of the hands of weak people, when they attempt to write. In a manufcript epif- tle of one of my correfpondents, which is written in a fmall hand, I obferved from four to fix zigzags in the perpendicular ftroke of every letter, which fhews that both the contractions of the fingers, and intervals between them^ muft have been per- formed in very fhort periods of time. The times of contraction of the mufcles of enfeebled people being lefs, and the intervals between thcfe contractions being lefs aifo, accounts for the quick pulfe in fevers with debility, and in dying animals. The ihartnefs of the intervals between one contraction and another in weak conftitutions, is probably owing to the general deficiency of the quantity of the fpirit of animation, and that therefore there is a lefs quantity of it to be received 43 OF STIMULUS Slct. XII. i. . received at each interval of the activity of the fibres. Hence in repeated motions, as of the fingers in performing on the harpfi- chord, it would at firft fight appear, that fwiftuefs and ftrength were incompatible ; nevertheiefs the iingle contraction of a inuf- cle is performed with greater velocity as well as with greater :ce by vigorous conftitutions, as in throwing a javelin. There is however another circumftance, which may often contribute to caufe the quicknefs of the pulfe in nervous fevers, as in animals bleeding to death in the flaughter-houfe ; which is the deficient quantity of blood 5 whence the heart is but half diftended, and in confequence fooner contracts. See Seel:. XXXII. 2. r. For we mud not confound frequency of repetition with quicknefs of motion, or the number of pulfations with the ve- locity, with which the fibres, which conftitute the coats of the arteries, contract themfelves. For where the frequency of the pulfations is but ieventy-five in a minute, as in health ; the con- tracting fibres, which conftitute the fides of the arteries, may move through a greater fpace in a given time, than where the frequency of puliation is one hundred and fifty in a minute, as in fome fevers with great debility. For if in thofe fevers the arceries do not expand themfelves in their diaftole to more than half the ufual diameter of their diaftole in health, the fibres which conftitute their coats, will move through a lefs fpace in a minute than in health, though they make two pulfations for c.ie. Suppofe the diameter of the artery during its fyftole to be- cne line, and that the diameter of the fame artery during its di- aftole is in health four lines, and in a fever with great debility only two lines. It follows that the arterial fibres Contract in health from a circle of twelve lines in circumference to a circle of three lines in circumference, that is they move through a fpace of nine lines in length. While the arterial fibres in the fever with debility would twice contract from a circle of fix lines to a circle of three lines ; that is while they move through a fpace equal to fix lines. Hence though the frequency of pulfation in fever be greater as two to one, yet the velocity of contract lion in health is greater as nine to fix, eras three to two. On the contrary in inflammatory difeafes with ftrength, as in the pleurify, the velocity of the contracting fides of the arteries is much greater than in health : for if we fuppofe the number of pulfations in a pleurify to be half as much more than in health, that is as one hundred and twenty to eighty, (which is about what generally happens in inflammatory difeafes) and if the di- a ..- ter of the artery in diaftoie^e one third greater than in * health, Sect. XII. i. 5. AND EXERTION. 49 health, which I believe is near the truth, the refult will be, that the velocity of the contractile fides of the arteries will be in a pleurify as two and a half to one, compared to the velocity c£ their contraction in a date of health; for if the circumference of the fyflole of the artery be three lines, and the diaftole in health be twelve lines in circumference, and in a pleurify eighteen lines ; and fecondly, if the artery pulfates thrice in the difeafed ftate for twice in the healthy one, it follows, that the velocity of contraction in the difeafed date to that in the healthy ftate will be forty-five to eighteen, or as two and a half to one. From hence it would appear, that if we had a criterion to de- termine the velocity of the arterial contractions, it would at the fame time give us their ftrength, and thus be of more fervice in diftinguifhing difeafes, than the knowledge of their frequency., As fuch a criterion cannot be had, the frequency of puliation, the age of the patient being allowed for, will in fome meafure afiift us to diftinguifh arterial ftrength from arterial debility, fince in inflammatory difeafes with ftrength the frequency fel- dom exceeds one hundred and eighteen or one hundred and. twenty pulfations in a minute ; unlefs under fome peculiar cir- cumstance, as the great additional ftimuli of wine or of exter- nal heat. 5. After a mufcle or organ of fenfe has been excited intb contraction, and the fenforial power ceafes to act, the laft filia- tion or configuration of it continues ; unlefs it be diflurbed by the action of fome antagonift fibres, or other extraneous power. Thus in weak or languid people, wherever they throw their limbs on their bed or fofa, there they lie, till another exertion changes their attitude ; hence one kind of ocular fpectra feems. to be produced after looking at bright objects •, thus when a fire-flick is whirled round in the night, there appears in the eye a complete circle of fire ; the action or configuration of one part of the retina not ceafing before the return of the whirling fire. Thus if any one looks at the fetting fun for a fhort time, and then covers his clofed eves with his hand, he will for manv ^qc- ondsoftime perceive the image of the fun on his retina. A fimilar image of all other bodies would remain fome time in the eye, but is effaced by the eternal change of the motions of the extremity of this nerve in our attention to other objects. See Sect. XVII. 1.3. on Sleep. Hence the dark fpots, and other ocular fpectra, are more frequently attended to, and remain longer in the eyes of weak people, as after violent exercife, in- toxication, or want of fleep. 6. A contraction of the fibres (omewhat greater than, ufual VQL> L H intrc d ... •, 50 OF STIMULUS Sect. XII. t. 7, introduces pleafurable fenfation into the fyftem, according to the fourth law of animal caufation. Hence the pleafure in the be- ginning of drunkennefs is owing to the increafed action of the fyftem from the fiimulus of vinous fpirit or of opium. If the contractions be fiill greater in energy or duration, painful fen- fations are introduced, as in confequence of great heat, or cauf- tic applications, or fatigue. If any part of the fyftem, which is ufed to perpetual activity, as the ftomach, or heart, or the fine veflels of the fkin, ads for a time with lefs energy, another kind of painful fenfation enfues, which is called hunger, or faintnefs, or cold. This occurs in a lefs degree in the locomotive mufcles, and is called wearifome- nefs. In the two former kinds of fenfation there is an expendi- ture of fenforial power, in thefe latter there is an accumulation Of it. 7. We have ufed the words exertion of fenforial power as a general term to exprefs either irritation, fenfation, volition, or affociation ; that is, to exprefs the activity or motion of the fpirit of animation, at the time it produces the contractions of the fibrous parts of the fyftem. It may be fuppofcd that there may exift a greater or lefs mobility of the fibrous parts of our fyftem, or a propensity to be ftimulated into contraction by the greater or lefs quantity or energy of the fpirit of animation ; and that hence if the exertion of the fenforial power be in its natural Hate, and the mobility of the fibres be increafed, the fame quan- tity of fibrous contraction will be caufed, as if the mobility of the fibres continues in its natural ftate, and the fenforial exertion be increafed. Thus it may be conceived, that in difeafes accompanied with, ftrength, as in inflammatory fevers with arterial ftrcngth, that the caufe of greater fibrous contraction may exift in the increaf- ed mobility of the fibres, whofe contractions are thence both more forcible and more frequent. And that in difeafes attended with debility, as in nervous fevers, where the fibrous contrac- tions are weaker, and more frequent, it may be conceived that the caufe confifts in a decreafe of mobility of the fibres ; and that thofe weak conftitutions, which are attended with cold extremities and large pupils of the eyes, may poiTefs lefs mobil- ity of the contractile fibres, as well as lefs quantity of exertion of the fpirit of animation. In anfwer to this mode of reafoning it may be fufBcient to ob- ferve, that the contractile fibres confift of inert matter, and when the fenforial power is withdrawn, as in death, they pofTefs no power of motion at all, but remain in their laft ftate, whether of contraction or relaxation, and muft thence deiive the whole of v Sect. XII. i. 7. AND EXERTION. * 51 of this property from the fpirit of animation. At the fame time it is not improbable, that the moving fibres of ftrong people may poflefs a capability of receiving or containing a greater quantity of the fpirit of animation than thofe of weak people. In every contraction of a fibre there is an expenditure of the fenforial power, or fpirit of animation ; and where the exertion of this fenforial power has been for fome time increafed, and the mufcles or organs of fenfe have in confequence acted with greater energy, its propenfity to activity is proportionally leffen- ed ; which is to be afcribed to the exhauftion or diminution of its quantity. On the contrary, where there has been lefs fibrous contraction than ufual for a certain time, the fenforial power or fpirit of animation becomes accumulated in the inactive part of the fyftem. Hence vigour fucceeds reft, and hence the propen- fity to action of all our organs of fenfe and mufcles is in a ftate of perpetual fluctuation. The irritability for inflance of the retina, that is, its quantity of fenforial power, varies every mo- ment according to the brightnefs or obfcurity of the object lad beheld compared with the prefent one. The fame occurs to our fenfe of heat, and to every part of our fyftem, which is ca- pable of being excited into action. When this variation of the exertion of the fenforial power be- comes much and permanently above or beneath the natural quantity, it becomes a difeafe. If the irritative motions be too great or too little, it (hews that the ftimulus of external things affects this fenforial power too violently or too inertly. If the fenfitive motions be too great or too little, the caufe arifes from the deficient or exuberant quantity of fenfation produced in confequence of the motions of the mufcular fibres or organs of fenfe ; if the voluntary actions are difeafed the caufe is to be looked for in the quantity of volition produced in confequence of the defire or averfion occafioned by the painful or pleafurable fenfations above mentioned. And the difeafes of aflbciation probably depend on the greater or lefs quantity of the other three fenforial powers by which they were formed. From whence it appears that the propenfity to action, wheth- er it be called irritability, fenfibility, vohintarity, or aflociability, is only another mode of expreflion for the quantity of fenforial power' refiding in the organ to be excited. And that on the contrary the words inirritability and infenfibility, together with inaptitude to voluntary and aflbciate motions, are fynonymous with deficiency of the quantity of fenforial power, or of the fpirit of animation, refiding in the organs to be excited, II, Of 52 OF STIMULUS • Sec*. XII. 2. i. II. Of fenforial Exertion. i. There are three circurnftances to be attended to in the production of animal motions. ift. The ftimulus. 2d. The fenforial power. 3d. The contractile fibre, ift. A ftimulus, external to the organ, originally induces into action the fenfo- rial faculty termed irritation ; this produces the contraction of the fibres, which, if it be perceived at all, introduces pleafure or p;tin ; which in their active ftate are termed fenfation ; which is another fenforial faculty, and occasionally produces contrac- tion of the fibres ; this pleafure or pain is therefore to be con- fidered as another ftimulus, which may either act alone or in conjunction with the former faculty of the fenforium termed irritation. This new ftimulus of pleafure or pain either induces into action the fenforial faculty termed fenfation, which then produces the contraction of the fibres ; or it introduces defire or averfion, which excite into action another fenforial faculty, termed volition, and may therefore be confidered as another ftimulus, which either alone or in conjunction with one or both of the two former faculties of the fenforium produces the con- traction of animal fibres. There is another fenforial power, that of affociation, which perpetually, in conjunction with one or more of the above, and frequently fmgly, produces the con- traction of animal fibres, and which is itfelf excited into action by the previous motions of contracting fibres. Now as the fenforial power, termed irritation, refiding in any particular fibres, is excited into exertion by the ftimulus of ex- ternal bodies acting on thefe fibres ; the fenforial power, termed fenfation, refiding in any particular fibres is excited into exertion by the ftimulus of pleafure or pain acting on thofe fibres ; the fenforial power, termed volition, refiding in any particular fibres is excited into exertion by the ftimulus of defire or averfion ; and the fenforial power, termed affociation, refiding in any par- ticular fibres, is excited into a tion by the ftimulus of other fi- brous motions, which had frequently preceded them. The word ftimulus may therefore be ufed without impropriety of ^e, for any of thefe four caufes, which excite the four fenforial powers into exertion. For though the immediate caufe of volition has generally been termed a motive ; and that of ii .on only has generally obtained the name of Jlimulus : yet as the immediate caufe, which excites the fenforial powers enfation, or of affociation, into exertion, have obtained no general name, we fliall ufe the word ftimulus for them all. Kence the quantity of motion produced in any particular t o£ i. :em will be as the quantity of ftimulus, and Sect. XII. 2. 1. AND EXERTION. $3 and the quantity of fenforial power, or fpirit of animation, re- dding in the contracting fibres. Where both thefe quantities are vxz2.t,J}nngth is produced, when that word is applied to the motions of animal bodies. Where either of them is deficient, nveaknefs is produced, as applied to the motions of animal bodies. Now as the fenforial power, or fpirit of animation, is perpet- ually exhaufted by the expenditure of it in fibrous contractions, and is perpetually renewed by the fecretion or production of it in the brain and fpinal marrow, the quantity of animal ftrength muft be in a perpetual ftate of fluctuation on this account ; and if to this be added the unceafmg variation of all the four kinds of ftimulus above defcribed, which produce the exertions of the fenforial powers, the ceafelefs viciflitude of animal ftrength be- comes eafily comprehended. If the quantity of fenforial power remains the fame, and the quantity of ftimulus be leflened, a weaknefs of the fibrous con- tractions enfues, which may be denominated debility from defecl of ftimulus* If the quantity of ftimulus remains the fame, and the quantity of fenforial power be leffened, another kind of weaknefs enfues, which may be termed debility from defecl of fen- forial power ; the former of thefe is called by Dr. Brown, in his Elements of Medicine, direct debility, and the latter indi- rect debility. The coincidence of fome parts of this work with correfpondent deductions in the Brunonian Elementa Medi- cinal, a work (with fome exceptions) of great genius, muft be confidered as confirmations of the truth of the theory, as they were probably arrived at by different trains of reafoning; Thus in thofe who have been expofed to cold and hunper there is a deficiency of ftimulus. While in nervous fever there is a deficiency of fenforial power. And in habitual drunkards, in a morning before their ufual potation, there is a deficiency both of ftimulus and of fenforial power. While, on the other hand, in the beginning of intoxication there is an excefs of ftim- ulus ; in the hot-ach, after the hands have been immerfed in fnow there is a redundancy of fenforial power ; and in inflam- matory difeafes with arterial ftrength, there is an excefs of both. Hence if the fenforial power be leflened, while the quantity of ftimulus remains the fame, as in nervous fever, the frequen- cy of repetition of the arterial contractions may continue, but their force in refpect to removing obitacles, as m promoting the circulation of the blood, or the velocity of each contraction, will be diminiihed, that is, the animal ftrength will be leflened. And fecondly, if the quantity of fenforial power b^leflened, and the ftimulus be increafed to a certain degree, as in giving opium a in 54 OF STIMULUS Sect. XII. 2. i„ in nervous fevers, the arterial contractions may be performed more frequently than natural, yet with lefs ftrength. And thirdly, if the fenforiai power continues the fame in re- fpecl to quantity, and the ftimulus be fomewhat diminifhed,as in going into a darkifh room, or into a coldiih bath, fuppofe of a- bout eighty degrees of heat, as Buxton-bath, a temporary weak- nefs of the affected fibres is induced, till an accumulation of fen- foriai power gradually fucceeds, and counterbalances the de- ficiency of ftimulus, and then the bath ceafes to feel cold, and the room ceafes to appear dark ; becaufe the fibres of the fub- cutaneous veilcls, or of the organs of fenfe, act with their ufu- al energy. A fet of mufcular fibres may thus be ftimulated into violent exertion, that is, they may act frequently, and with their whole fenforiai power, but may neverthelefs not act ftrongly ; becaufe the quantity of their fenforiai power was originally fmall, or was previoufly exhaufted. Hence a ftimulus may be great, and the irritation in confequence act with its full force, as in the hot paroxyfm s of nervous fever ; but if the fenforiai power, termed irritation, be fmall in quantity, the force of the fibrous contrac- tions, and the times of their continuance in their contracted Hate, will be proportionally fmall. In the fame manner in the hot paroxyfm of putrid fevers, which are (hewn in Sect. XXXIII. to be inflammatory fevers with arterial debility, the fenforiai power termed fenfation is ex- erted with great activity, yet the fibrous contractions, which produce the circulation of the blood, are performed without Strength, becaufe the quantity of fenforiai power then refiding in that part of the fyftem is fmall. Thus in irritative fever with arterial ftrength, that is, with excefs of fpirit of animation, the quantity of exertion during the hot part of the paroxyfm is to be eftimated from the quan- tity of ftimulus, and the quantity of fenforiai power, while in fenfitive (or inflammatory) fever with arterial ftrength, that is, with excefs of fpirit of animation, the violent and forcible ac- tions of the vafcular fyftem during the hot part of the paroxyfm are induced by the exertions of two fenforiai powers, which are excited by two kinds of ftimulus. Thefe are the fenforiai pow- er of irritation excited by the ftimulus of bodies external to the moving fibres, and the fenforiai power of fenfation excited by the pain in confequence of the increafed contractions of thofe moving fibres. And in ie people in fome cafes the force of their mufcu- lar actions wiil be in proportion to the quantity of fenforiai .pow Ich they pofiefs, and thexmantity of the ftimulus of defire Sect. XII. 2. 2. AND EXERTION. |j defire or averfion, which excites their volition into action. At the fame time in other cafes the ftimulus of pain or pleafure, and the ftimulus of external bodies, may excite into action the fenforial powers of fenfation and irritation, and thus add great- er force to their mufcular actions. 2. The application of the ftimulus, whether that ftimulus be fome quality of external bodies, or pleafure or pain, or defire or averfion, or a link of aflbciation, excites the correfpondent fenfo- rial power into action, and this caufes the contraction of the fi- bre. On the contraction of the fibre a part of the fpirit of ani- mation becomes expended, and the fibre ceafes to contract, though the ftimulus continues to be applied ; till in a certain time the fibre having received a fupply of fenforial power is ready to contract again if the ftimulus continues to be applied. If the ftimulus on the contrary be withdrawn, the fame quanti- ty of quiefcent fenforial power becomes refident in the fibre as before its contraction ; as appears from the readinefs for action of the large locomotive mufcles of the body in a fhort time af- ter common exertion. But in thofe mufcular fibres, which are fubject to conftant ftimulus, as the arteries, glands, and capillary vefTels, another phenomenon occurs, if their accuftomed ftimulus be withdrawn 5 which is, that the fenforial power becomes accumulated in the contractile fibres, owing to the want of its being perpetually expended, or carried away, by their ufual unremitted contrac- tions. And on this account thofe mufcular fibres become af- terwards excitable into their natural actions by a much weaker ftimulus ; or into unnatural violence of action by their accuf- tomed ftimulus, as is feen in the hot fits of intermittent fevers, which are in confequence of the previous cold ones. Thus the minute vefTels of the fkin are conftantly ftimulated by the fluid matter of heat ; if the quantity of this ftimulus of heat be a while diminifhed, as in covering the hands with fnow, the vefTels ceafe to act, as appears from the palenefs of the fkin ; if this cold application of fnow be continued but a fhort time, the fenforial power, which had habitually been fupplied to the fi- bres, becomes now accumulated in them, owinp to the want of its being expended by their accuftomed contractions. And thence a lefs ftimulus of heat will now excite them into violent contractions. If the quiefcence of fibres, which had previoufly been fubjeel: to perpetual ftimulus, continues a longer time ; or their accus- tomed ftimulus be more completely withdrawn j the accumula- tion of fenforial power becomes ftill greater, as in thofe expofed to cold and hunger ; pain is produced, and the organ gradually dies $6 OF STIMULUS Sect. XII. 2. 3, dies from the chemical changes, which take place in it ; or it is at a great diftance of time reftored to action by ftimulus appli- ed with great caution in fmall quantity, as happens to fome larger animals and to many infects, which during the winter months lie benumbed with cold, and are faid to fleep, and to perfons apparently drowned, or apparently frozen to death. Snails have" been laid to revive by throwing them into water af- ter having been many years (hut up in the cabinets of the curi- ous •, and eggs and feeds in general are reftored to life after many months of torpor by the ftimulus of warmth and moifture. The inflammation of fchirrous tumours, which have long exifted in a ftate of inaction, is a procefs of this kind ; as well as the fenfibility acquired by inflamed tendons and bones, which had at their formation a fimilar fenfibility, which had fo long lain dormant in their uninilamed (late. 3. If after long quiefcence from defect of ftimulus the fibres, which had previoufly been habituated to perpetual ftimulus, are again expofed to but their ufual quantity of it ; as in thofe who have fuffered the extremes of cold or hunger j a violent exer- tion of the affected organ commences, owing, as above explain- ed, to the great accumulation of fenforial power. This violent exertion not only diminilhes the accumulated fplrit of anima- tion, but at the fame time induces pleafure or pain into the fyf- tem, which, whether it be fucceeded by inflammation or not, becomes an additional ftimulus, and acting along with the for- mer one, produces ftill greater exertions ; and thus reduces the fenforial power in the contracting fibres beneath its natural quantity. ^^ When the fpirit of animation is thus exhaufled by ufelefs ex- ertions, the organ becomes torpid or unexcitable into action, and a fecond fit of quiefcence fucceeds that of abundant activity. During this fecond fit of quiefcence the fenforial power be- comes again accumulated, and another fit of exertion follows in train. Thefe viciflitudes of exertion and inertion of the arterial fyftem conftitute the paroxyfms of remittent fevers ; or inter- mittent ones, when there is an interval of the natural action of the arteries between the exacerbations. In thefe paroxifms of fevers, which confift of the libration of the arterial fyftem between the extremes of exertion and qui- efcence, either the fits become lefs and lets violent from thexon- tractile fibres becoming lefs excitable to the ftimulus by habit, that is, by becoming accuftomed to it, as explained below XII. 3. 1. or the whole fenforial power becomes exhaufted, and the arteries ceafe to beat, and the patient dies in the cold part of the parcxifrn. Or feeondly, fo much pair, is introduced into I r~ Sect. XII. 2. 4. AND EXERTION. S7 the fyftem by the violent contractions of the fibres, that inflam- mation arifes, which prevents future cold fits by expending a part of the fenforial power in the extenfion of old vefTels or the production of new ones ; and thus preventing the too great ac- cumulation or exertion of it in other parts of the fyftem 5 or which by the great increafe of ftimulus excites into great action the whole glandular fyftem as well as the arterial, and thence a greater quantity of fenforial power is produced in the brain, and thus its exhauftion in any peculiar part of the fyftem ceafes to be effected. 4. Or thirdly, in confequence of the painful or pleafurabie fenfation above mentioned, defire and averfion are introduced, and inordinate volition fucceeds ; which by its own exertions expends fo much of the fpirit of animation, that the two other fenforial faculties, or irritation and fenfation, act fo much more feebly ; that the paroxyfms of fever, or that libration between the extremes of exertion and inactivity of the arterial fyftem, gradually fubfides. On this account a temporary infanity is a favourable fign in fevers, as I have had fome opportunities of obferving. III. Of repeated Stimulus, 1. When a ftimulus is repeated more frequently than the ex- penditure of fenforial power can be renewed in the acting or- gan, the effect of the ftimulus becomes gradually diminifhed. Thus if two grains of opium be fwallowed by a perfon unufed to fo ftrong a ftimulus, all the vafcular fyftems in the body act with great energy, all the fecretions and the abforption from thofe fecreted fluids are increafed in quantity \ and pleafure or pain are introduced into the fyftem, which adds an additional ftimulus to that already too great. After fome hours the fenfo- rial power becomes diminifhed in quantity, expended by the great activity of the fyftem 5 and thence, when the ftimulus of the opium is withdrawn, the fibres will not obey their ufual de- gree of natural ftimulus, and a confequent torpor or quiefcence fucceeds, as is experienced by drunkards, who on the day after a great excefs of fpirituous potation feel indigeftion, head-ache, and general debility. In this fit of torpor or quiefcence of a part or of the whole of the fyftem, an accumulation of the fenforial power in the af- fected fibres is formed, and occafions a fecond paroxyfm of ex- ertion by the application only of the natural ftimulus, and thus a libration of the fenforial exertion between one excefs and the ether continues for two or three days, where the ftimulus was Vol. I. I violent; 5$ OF STIMULUS Sect. XII. 3. i. violent in degree ; and for weeks in fome fevers, from the ftim- ulus of contagious matter. But if a fecond dofe of opium be exhibited before the fibres have regained their natural quantity of fenforial power, its ef- fect will be much lefs than the former, becaufe the fpirit of an- imation or fenforial power is in part exhaufted by the previous excefs of exertion. Hence all medicines repeated too frequent- ly gradually lofe their effect, as opium and wine. Many things of difagreeable tafte at firft ceafe to be difagreeable by frequent repetition, as tobacco ; grief and pain gradually diminilh, and at length ceafe altogether, and hence life itfelf becomes toler- able. Befides the temporary diminution of the fpirit of animation or fenforial power, which is naturally ftationary or refident in every living fibre, by a fingle exhibition of a powerful ftimulus, the contractile fibres themfelves, by the perpetual application of a new quantity of ftimulus, before they have regained their nat- ural quantity of fenforial power, appear to fuffer in their capa- bility of receiving fo much as the natural quantity of fenforial power ; and hence a permanent deficiency of fpirit of anima- tion takes place, however long the ftimulus may have been withdrawn. On this caufe depends the permanent debility of thofe, who have been addicted to intoxication, the general weak- nefs of old age, and the natural debility or inirritability of thofe, who have pale fkins and large pupils of their eyes. There is a curious phenomenon belongs to this place, which has always appeared difficult of folution •, and that is, that opi- um or aloes may be exhibited in fmall dofes at firft, and gradu- ally increafed to very large ones without producing ftupor or diarrhoea. In this cafe, though the opium and aloes are given in fuch fmall dofes as not to produce intoxication or catharfis, yet they are exhibited in quantities fufficient in fome degree to cxhauft the fenforial power, and hence a ftronger and a ftrong- er dofe is required ; otherwife the medicine would foon ceafe to aft at all. On the contrary, if the opium or aloes be exhibited in a large dofe at firft, fo as to produce intoxication or diarrhoea ; after a few repetitions the quantity of either of them may be diminifh- ed, and they will ftill produce this effect. -For the more pow- erful ftimulus difievers the progreflive catenations of animal mo- tions, defcribed in Sect. XVII. and introduces a new link be- tween them ; whence every repetition ftrengthens this new af- fociation or catenation', and the ftimulus may be gradually de- creafed, or be nearly withdrawn, and yet the effect fhall con- tinue y becaufe the fenforial power of aflbciaiion. or catenation being Sect. XII. 3. 2. AND EXERTION. 59 being united with the ftimulus, increafes in energy with every repetition of the catenated circle ; and it is by thefe means that all the irritative alTociations of motions are originally produced. Thus if the Peruvian bark be given in the intervals between the fits of intermittent fever in fuch fmall dofes, as not to pre- vent the returns of fever, the conftitution ceafes to obey its ftimulus, and the difeafe cannot be cured even by the largefl dofes of bark, unlefs the patient ceafes to take any for a few days previous to the exhibition of larger dofes. But if large dofes be at firft exhibited, fo as to prevent the return of fever, fmall ones taken afterwards will continue to prevent the return of it. . 2. When a ftimulus is repeated at fuch diftant intervals of time, that the natural quantity of fenforial power becomes com- pletely reftored in the acting fibres, it will act with the fame en- ergy as when firft applied. Hence thofe who have lately accuf- tomed themfelves to large dofes of opium by beginning with fmall ones, and gradually increafing them, and repeating them frequently, as mentioned in the preceding paragraphs ; if they intermit the ufe of it for a few days only, muft begin again with as fmall dofes as they took at firft, other wife they will experi- ence the inconveniences of intoxication. On this circumftance depend the conftant unfailing effects of the various kinds of ftimulus, which excite into action all the vafcular fyftems in the body ; the arterial, venous, abforbent, and glandular vefTels, are brought into perpetual unwearied ac- tion by the fluids, which are adapted to ftimulate them ; but thefe have the fenforial power of affociation added to that of ir- ritation, and even in fome degree that of fenfation, and even of volition, as will be fpoken of in their places; and life itfelf is thus carried on by the production of fenforial power being equal to its wafte or expenditure in the perpetual movement of the vafcu- lar organization. 3. When a ftimulus is repeated at uniform intervals of time with fuch diftances between them, that the expenditure of fen- forial power in the acting fibres becomes completely renewed, the effect is produced with greater facility or energy. For the fenforial power of aflbciation is combined with the fenforial power of irritation, or, in common language, the acquired hab- it aflifts the power of the ftimulus. This circumftance not only obtains in the annual and diur- nal catenations of animal motions explained in Seel:. XXXVI. but in every lefs circle of actions or ideas, as in the burthen of a fong, or the iterations of a dance 5 and conftitutes the pleas- ure 6o OF STIMULUS Sect. XII. 3. 4. ure we receive from repetition and imitation ; as treated of in Seel. XXII. 2. 4. When a ftimulus has been many times repeated at uni- form intervals, fo as to produce the complete action of the or- gan, it may then be gradually diminifhed, or totally withdrawn, and the action of the organ will continue. For the fenforial power of afTociation becomes united with that of irritation, and by frequent repetition becomes at length of fumcient energy to carry on the new link in the circle of actions, without the irri- tation which at firft introduced it. Hence, when the bark is given at ftated intervals for the cure of intermittent fevers, if fixty grains of it be given every three hours for the twenty-four hours preceding the expected parbxyfm, fo as to ftimulate the defective part of the fyftem in- to action, and by that means to prevent the torpor or quiefcence of the fibres, which conftitutes the cold fit ; much lefs than half the quantity, given before the time at which another paroxyfm of quiefcence would have taken place, will be fumcient to pre- vent it ; becaufe now the fenforial power, termed afTociation, acts in a twofold manner. Firft, in refpect to the period of the catenation in which the cold fit was produced, which is now difTeyered by the ftronger ftimulus of the firft dofes of the bark ; and, fecondly, becaufe each dofe of bark being repeated at peri- odical times, has its effect increafed by the fenforial faculty of afTociation being combined with that of irritation. Now, when fixty grains of Peruvian bark are taken twice a day, fuppofe at ten o'clock and at fix, for a fortnight, the irrita- tion excited by this additional ftimulus becomes a part of the diurnal circle of actions, and will at length carry on the increaf- ed action of the fyftem without the afliftance of the ftimulus of the bark. On this theory the bitter medicines, chalybeates, and opiates in appropriated dofes, exhibited for a fortnight, give permanent ftrength to pale feeble children, and other weak conftkutions. 5. When a defect of ftimulus, as of heat, recurs at certain diurnal intervals, which induces fome torpor or quiefcence of a part of the fyftem, the diurnal catenation of actions becomes difordered, and a new afTociation with this link of torpid action i i formed -3 on the next period the quantity of quiefcence will be incr I, fuppofe the fame defect of ftimulus to recur, becaufe now the new afTociation confpires with the defective irritation in introducing the torpid action of this part of the diurnal cat- enation. In this manner many fever-fits commence, where the patient is for fome clays indifpofed at certain hours, before the cold Sect. XII. 3. 6. AND EXERTION. 61 cold paroxyfm of fever is completely formed. See Sect. XVII. 3. 3. on Catenation of Animal Motions. 6. If a ftimulus, which at firft excited the affected organ into fo preat exertion as to produce fenfation, be continued for a certain time, it will ceafe to produce fenfation both then and when repeated, though the irritative motions in confequence of it may continue or be re-excited. Many catenations of irritative motions were at firft fucceed- cd by fenfation, as the apparent motions of objects when we walk pad them, and probably the vital motions themfelves in the early ftate 'of our exiftence. But as thofe fenfations were followed by no movements of the fyftem in confequence of them, they gradually ceafed to be produced, not being joined to any fucceeding link of catenation. Hence contagious matter, which has for fome weeks ftimulated the fyftem into great and permanent fenfation, ceafes afterwards to produce general fenfa- tion, or inflammation, though it may ftill induce topical irrita- tions. See Sea. XXXIII. 2. 8. XIX. 10. Our abforbent fyftem then feems to receive thofe contagious matters, which it has before experienced, in the fame manner as it imbibes common moifture or other fluids ; that is, without being thrown into fo violent action as to produce fenfation •, the confequence of which is an increafe of daily energy or activity, till inflammation and its confequences fucceed. 7. If a ftimulus excites an organ into fuch violent contrac- tions as to produce fenfation, the motions of which organ had not ufually produced fenfation, this new fenforial power, added to the irritation occafioned by the ftimulus, increafes the activ- ity of the organ. And if this activity be catenated with the di- urnal circle of actions, an increasing inflammation is produced ; as in the evening paroxyfms of fmall-pox, and other fevers with inflammation. And hence fchirrous tumours, tendons and membranes, and probably the arteries themfelves become in- flamed, when they are ftrongly ftimulated. IV. Of Stimulus greater than natural. 1. A quantity of ftimulus greater than natural, producing an increafed exertion of fenforial power, whether that exertion be in the mode of irritation, fenfation, volition, or afTociaticn, dimm- ifhes the general quantity of it. This fact is obfervable in the progrefs of intoxication, as the increafed quantity or energy of the irritative motions, owing to the ftimulus of vinous fpirit, in- troduces much pleafurable fenfation into the fyftem, and much exertion of mufcular or fenfual motions in confequence of this increafed 62 OF STIMULUS Sect. XII. 4. 2. increafed fenfation ; the voluntary motions, and even the aflbci- ate ones, become much impaired or diminiihed ; and delirium and daggering fucceed. See Sect. XXI. on Drunkennefs. And hence the great proftration of the ftrength of the locomo- tive mufcles in fome fevers, is owing to the exhauftion of fenfo- rial power by the increafed action of the arterial fyftem. In like manner a ftimulus greater than natural, applied to a part of the fyftem, increafes the exertion of fenforial power in that part, and diminifhes it in fome other part. As in the com- mencement of fcarlet fever, it is ufual to fee great rednefs and heat on the faces and breads of children, while at the fame time their feet are colder than natural ; partial heats are obfervable in other fevers with debility, and are generally attended with torpor or quiefcence of fome other part of the fyftem. But thefe partial exertions of fenforial power are fometimes attend- ed with increafed partial exertions in other parts of the fyftem, -which fympathize with them, as the flulhing of the face after a full meal. Both thefe therefore are to be afcribed to fympathet- ic aflbciations, explained in Sect. XXXV. and not to general exhauftion or accumulation of fenforial power. 2. A quantity of ftimulus greater than natural, producing an increafed exertion of fenforial power in any particular organ, diminifhes the quantity of it in that organ. This appears from the contractions of animal fibres being not fo eafily excited by a lefs ftimulus after the organ has been fubjected to a greater. Thus after looking at any luminous object of a fmall fize, as at the fetting fun, for a lhort time, fo as not much to fatigue the eye, this part of the retina becomes lefs fenfible to fmaller quan- tities of light ; hence when the eyes are turned on other lefs lu- minous parts of the fky, a dark fpot is feen refembling the fhape of the fun, or other luminous object; which we laft behold. See Sect. XL. No. 2. Thus we are fome time before we can diftinguifh object^ in an obfeure room after coming from bright day-light, though the iris prefently contracts itfelf. We are not able to hear weak founds after loud ones. And the ftomachs of thofe who have been much habituated to the ftronger ftimulus of fermented or fpirituous liquors, are not excited into due action by weaker ones. 3. A quantity of ftimulus fomething greater than the laft mentioned, or longer continued, induces the organ into fpaf- modic action, which ceafes and recurs alternately. Thus on looking for a time on the fetting fun, fo as not greatly to fatigue the fight, a yellow fpectrum is feen when the eyes are clofed and covered, which continues for a time, and then difappears * »d recurs repeatedly before it entirely va nifties. See Sect. XL. No. Sect. XII. 4. 4- AND EXERTION. 63 No. 5. Thus the a£lion of vomiting ceafes and is renewed by intervals, although the emetic drug is thrown up with the firit effort. A tenefmus continues by intervals fome time after the exclufion of acrid excrement; and the pulfations of the heart of a viper are faid to continue fome time after it is cleared from its blood. In thefe cafes the violent contractions of the fibres produce pain according to law 4 ; and this pain constitutes an additional kind or quantity of excitement, which again induces the fibres into contraction, and which painful excitement is again renew- ed, and again induces contractions of the fibres with gradually diminifhing effect. 4. A quantity of flimulus greater than that lad mentioned, or longer continued, induces the antagonift mufcles into fpafmodic action. This is beautifully illuftrated by the ocular fpectra de- fcribed in Sect. XL. No. 6. to which the reader is referred. From thofe experiments there is reafon to conclude that the fa- ( tigued part of the retina throws itfelf into a contrary mode of action like ofcitation or pandiculation, as foon as the flimulus, which has fatigued it, is withdrawn ; but that it ftill remains li- able to be excited into action by any other colours except the colour with which it has been fatigued. Thus the yawning and ftretching the limbs after a continued action or attitude feems occafioned by the antagonift mufcles being ftimulated by their extenfion during the contractions of thofe in action, or in the fituation in which that action lafl left them. 5. A quantity of Stimulus greater than the laft, or. longer con- tinued, induces variety of convulfions or fixed fpafms either of the affected organ or of the moving fibres in the other parts of the body. In refpect to the fpectra in the eye, this is well il- luftrated in No. 7 and 8, of Sect. XL. Epileptic convulfions, as the emprofthotonos and opisthotonos, with the cramp of the calf of the leg, locked jaw, and other cataleptic fits, appear to origi- nate from pain, as fome of thefe patients fcream aloud before the convulfion takes place 5 which feems at firfl to be an effort to relieve painful fenfation, and afterwards an effort to prevent it. In thefe cafes the violent contractions of the fibres produce fo much pain, as to conftitute a perpetual excitement -9 and that in fo great a degree as to allow but fmall intervals of relaxation of the contracting fibres as in convulfions, or no intervals at all as in fixed fpafms. 6. A quantity of ftimulus greater than the laft, or longer con- tinued, produces a paralyfis of the organ. In many cafes this paralyfis is only a temporary effect, as on looking long on a fmall area of bright red filk placed on a flaeet of white paper on the floor 64 OF STIMULUS Sect. XII. 5. 1. floor in a ftrong light, the red filk gradually becomes paler, and at length difappears ; which evinces that a part of the retina, by being violently excited, becomes for a time unaffected by the itimulus of that colour. Thus cathartic medicines, opiates, poi- fons, contagious matter, ceafe to influence our fyftem after it has been habituated to the ufe of them, except by the exhibition of increafed quantities of them ; our fibres not only become unaf- fected by ftimuli, by which they have previoufly been violently irritated, as by the matter of the fmaJl-pox or meafles ; but they alfo become unaffected by fenfation, where the violent exertions, which difabled them, were in confequence of too great quantity of fenfation. And laftly the fibres, which become difobedient to volition, are probably difabled by their too violent exertions in confequence of too great a quantity of volition. After every exertion of our fibres a temporary paralyfis fuc- ceeds, whence the intervals of all mufcular contractions, as men. tioned in No. 3 and 4 of this Section ; the immediate caufe of thefe more permanent kinds of paralyfis is probably owing in the f-ime manner to the too great exhauftion of the fpirit of anima- tion in the affected part ; fo that a ftronger ftimulus is required, or one of a different kind from that, which occafioned thofe too violent contractions, to again excite the affected organ into ac- tivity ; and if a ftronger ftimulus could be applied, it mult again induce paralyfis. For thefe powerful ftimuli excite pain at the fame time, that they produce irritation ; and this pain not only excites fibrous motions by its ftimulus, but it alfo produces volition ; and thus all thefe ftimuli acting at the fame time, and fometimes with the addition of their affociations, produce fo great exertion as to expend the whole of the fenforial power in the affected fibres. V. Of Stimulus lefs than natural. I. A quantity of ftimulus lefs than natural, producing a de- creafed exertion of fenforial power, occafions an accumulation of the general quantity of it. This circumftance is obfervable in the hemiplegia, in which the patients are perpetually mov- ing the mufcles, which are unaffected. On this account we awake with greater vigour after lleep, becaufe during fo many hours, the great ufual expenditure of fenforial power in the per- formance of voluntary actions, and in the exertions of our or- gans of fenfe, in confequence of the irritations occafioned by ex- ternal objects had been fufpended, and a coniequent accumula- tion had taken place. In like manner the exertion of the fenforial power lefs than natural Sect. XII. 5. 2. AND EXERTION. 6s natural In one part of the fyftem, is liable to produce an inefeafe of the exertion of it in fome other part. Thus by the action o£ vomiting, in which the natural exertion of the motions of the ftomach are deftroy#d or diminifhed, an increafed abforption of the pulmonary and cellular lymphatics is produced, as is known by the increafed abforption of the fluid depofited in them in dropfical cafes. But thefe partial quiefcences of fenforial power are alfo fometimes attended with other partial quiefcences, which fympathize with them, as cold and pale extremities from hun- ger. Thefe therefore are to be afcribed to the affociations of fympathy explained in Seel. XXXV. and not to the general accumulation of fenforial power. 2. A quantity of ftimulus lefs than natural, applied to fibres previously accuftomed to perpetual ftimulus, is fucceeded by ac- cumulation of fenforial power in the affected organ. The truth of this propofition is evinced, becaufe a flimulus lefs than nat- ural, if it be fomewhat greater than that above mentioned, will excite the organ fo circumftanced into violent activity. Thus on a frofty day with wind, the face of a perfon expofed to the v/ind is at firft pale and fhrunk ; but on turning the face from the wind, it becomes foon of a glow with warmth and fluming. The glow of the {kin in emerging from the cold-bath is owing to the fame caufe. It doss not appear, that an accumulation of fenforial power above the natural quantity is acquired by thofe mufcles, which are not fubject to perpetual ftimulus, as the locomotive mufcles : thefe, after the greateft fatigue, only acquire by reft their ufual aptitude to motion ; whereas the vafcular fyftem, as the heart and arteries, after a fhort quiefcence, are thrown into violent ac- tion by their natural quantity of ftimulus. Neverthelefs by this accumulation of fenforial power during the application of decreafed ftimulus, and by the exhauftion of it during the action of increafed ftimulus, it is wifely provided, that the actions of the vafcular mufcles and organs of fenfe are not much deranged by fmall variations of ftimulus ; as the quan- tity of fenforial power becomes in fome meafure inverfely as the quantity of ftimulus. 3. A quantity of ftimulus lefs than that mentioned above, and continued for fome time, induces pain in the affected orgtn, as the pain of cold in the hands, when they are immerfed in fnow, is owing to a deficiency of the ftimulation of heat. Hunger is a pain from the deficiency of the ftimulation of food. °Pam in the back at the commencement of ague-fits, and the hea beat) itching^ caifiics, and electricity. I. Philosophers have been much perplexed to underftand, in what manner we become acquainted with the external world ; infomuch that Dr. Berkeley even doubted its exiftence, from having obferved (as he thought) that none of our ideas refemble their correfpondent objects. Mr. Hume aflerts, that our belief depends on the greater diftinctnefs or energy of our ideas from perception ; and Mr. Reid has lately contended, that our belief of external objects is an innate principle neceflarily joined with our perceptions. So true is the obfervation of the famous Malbranch, " that our fenfes are not given us to difcover the efTences of things, but to acquaint us with the means of preferving our exiftence," (L. I. ch. v.) a melancholy reflection to philofophers ! Some philofophers have divided all created beings into material and immaterial : the former including all that part of being, which obeys the mechanic laws of action and reaction, but which can begin no motion of itfelf ; the other is the caufe of all motion, and is either termed the power of gravity, or 01 fpecific attraction, or the fpirit of animation. This immaterial agent is fuppofed to exift in or with matter, but to be quite dif- tinct from it, and to be equally capable of exiftence, after the matter, which now potteries it, is decompofed. Nor is this theory ill fupported by analogy, fince heat, elec- tricity, and magnetifm, can be given to or taken from a piece of iron ; and muft therefore exifl, whether feparated from the metal, or combined with it. From a parity of reafoning, the fpirit So PRODUCTION Sect. XIV. 2. / fpirit of animation would appear to be capable of exifling as well feparately from the body as with it. I beg to be underftood, that I do not wifh to difpute about words, and am ready to allow, that the powers of gravity, fpe- cific attraction, electricity, magnetifm, and even the fpirit of animation, may confift of matter of a finer kind ; and to believe, with St. Psul and Malbranch, that the ultimate caufe only of all motion is immaterial, that is God. St. Paul fays, " in him wc live and move, and have our being ;" and, in the 15th chapter to the Corinthian:^, diftinguiflies between the pfyche or living fpirit, and the pneuma or reviving fpirit. By the words fpirit of animation or fenforial power, I mean only that animal life, which mankind porTefles in common with brutes, and in fome degree even with vegetables, and leave the confideration of the immortal part of us, which is the object of religion, to thofe who treat of revelation. II. I . Of the Senfe of Touch, The firll ideas wc become acquainted with, are thofe of the fenfe of touch ; for the foetus mull experience fome varieties of agitation, and exert fome mufcular action, in the womb ; and rruy with great probability be fuppofed thus to gain fome ideas of its own figure, of that of the uterus, and of the tenacity of the fluid, that furrounds it, (as appears from the facts mention- ed in the fucceeding Seclion upon Inflincl.) Many of the organs of fenfe are confined to a fmall part of the body, as the noftrils, ear, or eye, whilft the fenfe of touch is ctiifufed over the whole fkin, but exifts with a more exquifite degree of delicacy at the extremities of the fingers and thumbs, and in the lips. The fenfe of touch is thus very commodioufly difpofed for the purpofe of encompafiing fmaller bodies, and for adapting itfelf to the inequalities of larger ones. The figure of fmall bodies feems to be learnt by children by their lips as much as by their fingers ; on which account they put every new ob- ject to their mouths, when they are fatiated with food, as well as when they are hungry. And puppies feem to learn their ideas of figure principally by the lips in their mode of play* We acquire our tangible ideas of objects either by the firnple preiTure of this organ of touch againft a folid body, or by moving our organ of touch along the furface of it. In the former cafe we learn the length and breadth of the object by the quan- tity of our organ of touch, that is imprcfTed by it : in the latter cafe we learn the length and breadth of objects by the continu- ance of their prefftire on our moving organ of touch- Sect. XIV. 2. a. OF IDEAS. 81 It is hence, that we are very flow in acquiring our tangible ideas, and very flow in recollecting them ; for if I now think of the tangible idea of a cube, that is, if I think of its figure, and of the folidity of every part of that figure, I muft conceive my- felf as palling my fingers over it, and feem in fome meafure to feel the idea, as I formerly did the imprefiion, at the ends of them, and am thus very flow in distinctly recollecting it. When a body comprefles any part of our fenfe of touch, what happens ? Firfl, this part of our fenforium undergoes a mechan- ical compreffion, which is termed a itimulus ; fecondly, an idea, or contraction of a part of the organ of fenfe is excited ; third- ly, a motion of the central parts, or of the whole fenforium, which is termed fenfation, is produced ; and thefe three coniti- tute the perception of folidity. 2. Of Figure, Motion, Time, Place, Space, Number. No one will deny, that the medulla of the brain and nerves has a certain figure ; which, as it is difFufed through nearly the whole of the body, mutt have nearly the figure of that body. Now it follows, that the fpirit of animation, or living principle, as it occupies this medulla, and no other part, (which is evinced by a great variety of cruel experiments on living animals^) it follows, that this fpirit of animation has alfo the fame figure as the medulla above defcribed. I appeal to common fenfe ! the fpirit of animation acts, Where does it act ? It acts wherever there is the medulla above mentioned ; and that whether the limb is yet joined to a living animal, or whether it be recently detached from it •, as the heart of a viper or frog will renew its contractions, when pricked with a pin, for many minutes of time after its exfection from the body. — Does it act any where elfe ? — No j then it certainly exifls in this part of fpace, and no where elfe ; that is, it hath figure ; namely, the figure of the nervous fyftem, which is nearly the figure of the body. When the idea of folidity is excited, as above explained, a part of the extenfive organ of touch is comprefTed by fome external body, and this part of the fenforium fo comprefTed exactly refembles ?n figure the figure of the body that comprefTed it. Hence, when we acquire the idea of folidity, we acquire at the fame time the idea of figure ; and this idea of figure, or motion of a part of the organ of touch, exactly refembles in its figure the figure of the body that occafions it ; and thus exactly acquaints us with this property of the external world. Now, as the whole univerfe with all its parts pofiefles a cer- tain form or figure, if &ny part of it moves, that form or figurf Vol, I.' M of S2 PRODUCTION Sect. XIV. 2. 2. of the whole is varied : hence, as motion is no other than a per- petual variation of figure, our idea of motion is alfo a real re- femblance of the motion that produced it. It may be faid in objection to this definition of motion, that an ivory globe may revolve on its axis, and that here will be a motion without change of figure. But the figure of the parti- cle x on one fide of this globe is not the fame figure as the figure of y on the other fide, any more than the particles themfelves are the lame, though they are fimilar figures ; and hence they cannot change place with each other without difturbing or changing the figure of the whole. Our idea of time is from the fame fource, but is more ab- itracted, as it includes only the comparative velocities of thefe variations of figure ; hence if it be afked, How long was this book in printing ? it may be anfwered, Whilft the fun was palling through Aries. Our idea of place includes only the figure of a group of bodies, not the figures of the bodies themfelves. If it be afked where is Nottinghamfhire, the anfwer is, it is furrounded by Derbyfhire, Lincolnfhire, and Leicefterfhire ; hence place is our idea of the figure of one body furrounded by the figures of other bodies. The idea of space is a more abftratled idea of place exclu- ding the group of bodies. The idea of number includes only the particular arrange- ments, or diftributions of a group of bodies, and is therefore on- ly a more abftracfted idea of the parts of the figure of the group of bodies ; thus when I fay England is divided into forty coun- ties, I only fpeak of certain divifions of its figure. Hence arifts the certainty of the mathematical fciences, as they explain thefe properties of bodies, which are exactly re- fembled by our ideas of them, whilft we are obliged to collect almoft all our other knowledge from experiment ; that is, by obferving the effects exerted by one body upon another. I feel myfelf much obliged by the accurate attention given to the firft volume of Zoonomia, and by the ingenious criticifms bellowed on it, by the learned writers of that article both in the Analvtical and Emjlifh Reviews. Some circumftances, in which their fentiments do not accord with thofe exprefTed in the work, I intend to reconfider, and to explain further at fome fu- ture time. One thing, in which both thefe gentlemen feem to difient from me, I fhall now mention, it is concerning the man- ner, in which we acquire the idea of figure ; a circumftance of great importance in the knowledge of our intellect, as it fhews the caufe of the accuracy of our ideas of motion, time, fpace, • number, Sect. XIV. 2. 2. OF IDEAS. , 83 number, and of the mathematical fciences, which are concerned in the menfurations or proportions of figure. This I imagine may have in part arifen from the prepoflef- fion, which has almofl univerfally prevailed, that ideas are im- material beings, and therefore poflefs no properties in common with folid matter. Which I fuppofe to be a fanciful hypothefis, like the flories of ghofls and apparitions, which have fo long amufed, and Hill amufe the credulous without any foundation in nature. The exiflence of our own bodies, and of their folidity, and of their figure, and of their motions, is taken for granted in my account of ideas ; becaufe the ideas themfelves are believed to confift of motions or configurations of folid fibres ; and the queftion now propofed is, how we become acquainted with the figures of bodies external to our organs of fenfe ? Which I can only repeat from what is mentioned in Seel. XIV. 2. 2. that if part of an organ of fenfe be flimulated into action, as of the fenfe of touch, that part fo flimulated into action mull poflefs figure, which muffc be fimilar to the figure of the body, which Simulates it. Another previous prepofTeflion of the mind, which may have rendered the manner of our acquiring the knowledge of .figure - lefs intelligible, may have arifen from the common opinion of the perceiving faculty refiding in the head ; whereas our daily experience fhews, that our perception (which confifls of an idea, and of the pleafure or pain it occafions) exifts principally in the organ of fenfe, which is flimulated into action ; as every one, who burns his finger in the candle, mud be bold to deny. When an ivory triangle is preffed on the palm of the hand, the figure of the furface of the part of the organ of touch thus comprefled is a triangle, refembling in figure the figure of the external body, which comprefles it. The adlion of the flimu- lated fibres, which conflitute the idea of hardnefs and of figure, remains in this part of the fenforium, which forms the fenk of touch ; but the fenforial motion, which conftitutes pleafure or pain, and which is excited in confequence of thefe fibrous mo- tions of the organ of fenfe, is propagated^to the central parts of the fenforium, or to the whole of it ; though this generally oc- curs in lefs degree of energy, than it exifls in the flimulated or- gan of fenfe ; as in the inftance above mentioned of burning a linger in the candle. Some, who have efpoufed the doctrine of the immateriality of ideas, have ferioufly doubted the exiflence of a material world, with which only our fenfes acquaint us ; and yet have affented to the exigence of fpirit, with which our fenfes cannot acquaint us ; 84 PRODUCTION Sect. XIV. 2. 3* us ; and have finally allowed, that all our knowledge is derived through the medium of our fenfes ! They forget, that if the fpirit of animation had no properties in common with matter, it could neither affect, nor be affected by the material body. But the know^dge of our own material exiftence being granted, which I fufpect few rational perfons will ferioufly deny, the ex- iftence of a material external world fellows in courfe ; as our perceptions, when we are awake and not infane, are diftinguifh- ed from thofe excited by fenfation, as in our dreams, and from thofe excited by volition or by aflbciation, as in infanity and reverie, by the power we have of comparing the prefent percep- tions of one fenfe with thofe of another, as explained in Seel:. XIV. 2. 5. Andalfo by comparing the tribes of ideas, which the fymbols of pictures, or of languages, fuggeft to us, by intui- tive analogy with our previous experience, that is, with the com- mon courfe of nature. See Oafs III. 2. 2. 3. on Credulity. 3. Of the Penetrability of Matter, The impombility of two bodies exifling together in the fame fpace cannot be deduced from our idea of folidity, or of figure. As ibon as we perceive the motions of objects that furround us, and learn that we poffefs a power to move our own bodies, we experience, that thofe objects, which excite in us the idea of folidity and of figure, oppofe this voluntary movement of our own organs ; as whilft I endeavour to comprefs between my hands an ivory ball into a fpheroid. And we are hence taught by experience, that our own body and thofe, which we touch, cannot exift in the fame part of fpace. But this by no means demonftrates, that no two bodies can exift together in the fame part of fpace. Galileo in the preface to his works feems to be of opinion, that matter is not impene- trable ; Mr. Mitchel, and Mr. Bofcowich in his Theoria Philof. Natur. have efpoufed this hypothefis : which has been lately publifhed by Dr. Prieftlev, to whom the world is much indebted for fo many important discoveries in fcience. (Hift. of Light and Colours, p. 39*..) The uninterrupted paffage of light through tranfparent bodies, of the electric aether through* metal- lic and aqueous bodies, and of the magnetic effluvia through all bodies, would feem to eivc fome probability to this opinion. Hence it appears, that beings may exift without poileHing the property of folidity, as well as they can exift without pofTeihng the properties, which excite our i'meii or rafte, and can thence occupy fpace without detruding other bod:.:, from it ; but we canno . jme a inted with fuch beings by our fenfe of touch, Sect. XIV. 2. 4- OF IDEAS. 85 touch, any more than we can with odours or flavours without our fenfes of fmell and tafte. But that any being can exift without exifling in fpace, is to my ideas utterly incomprehenfible. My appeal is to common fenfe. To be implies a when and a where ; the one is com- paring it with the motions of other beings, and the other with their fituations. If there was but one object, as the whole creation may be confidered as one objecl:, then I cannot alk where it exifts ? for there are no other objects to compare its fituation with. Hence if any one denies, that a being exifts in fpace, he denies, that there are any other beings but that one 5 for to anfwer the queftion, " Where dees it exift ?" is only to mention the fitu- ation of the objects that furrcund it. In the fame manner if it be afked— -« "When does a bein» exift i" The anfwer only fpecifies the fucceflive motions either of itfelf, or of other bodies ; hence to fay, a body exifts not in time>.is to fay, that there is, or was, no motion in the world, 4. Of the Spirit of Animation. But though there may exift beings in the univerfe, that have not the property of foiidity ; that is, which can pofiefs any part of fpace, at the fame time that it is occupied by other bodies ; yet there may be other beings, that can aflame this property of foiidity, or difrobe themfelves of it occafionally, as we are taught of fpirils, and of angels ; and it would feem, that the spirit of animation muft be endued with this property,, otherwife how could it occafionally give motion to the limbs of animals ? — or be itfelf ftimulated into motion by the obtrufions of fur- rounding bodies, as of light, or odour ? If the fpirit of animation was always necefTarily penetrable, it could not influence or be influenced by the foiidity of com- mon matter ; they would exift together, but could not detrude each other from the part of fpace, where they exift j that is, they could not communicate motion to each other. No two things can influence or affect each other, which have not fame prop* erty common to both of them ; for to influence or affect another body is to give or communicate fome property to it, that it had not before 5 but how can one body give that to another, which it does not pofiefs itfelf ? — The words imply, that they mufl agree in having the power or faculty of pofleffing fome common. property; Thus if one body removes another from the part of fpace, that it pojSefles, it muft have the power of occupying that fpace itfelf; and if (toe body communicates heat o] motion 10 85 PRODUCTION Sect. XIV. 2. 5; to another, it follows, that they have alike the property of pof- fefling heat or motion. Hence the fpirit of animation, at the time it communicates or receives motion from folid bodies, muft itfelf pofTefs fome property of folidity. And in confequence at the time it re- ceives other kinds of motion from light, it muft pofTefs that property, which light pofTefTes, to communicate that kind of motion j and for which no language has a name, unlefs it may be termed Vifibility. And at the time it is flimulated into oth- er kinds of animal motion by the particles of fapid and odorous bodies affecting the fenfes of tafte and fmell, it muft refemble thefe particles of flavour, and of odour, in poflTefling fome fim- ilar or correfpondent property ; and for which language has no name, unlefs we may ufe the words Saporofity and Odorofity for thofe common properties, which are pofTefled by our organs of tafte and fmell, and by the particles of fapid and odorous bodies ; as the words Tangibility and Audibility may exprefs the common property pofiefTed by our organs of touch, and of hearing, and by the folid bodies, or their vibrations, which af- fect thofe organs. 5. Finally, though the figures of bodies are in truth refem- bled by the figure of the part of the organ of touch, which is flimulated into motion ; and that organ refembles the folid body, which ftimulates it, in its property of folidity ; and though the fenfe of hearing refembles the vibrations of external bodies in its capability of being ftimulated into motion by thofe vibrations ; and though our other organs of fenfe refemble the bodies, that ftimulate them, in their capability of being ftimu- lated by them ; and we hence become acquainted with thefe properties of the external world ; yet as we can repeat all thefe motions of our organs of fenfe by the efforts of volition, or in confequence of*the fenfation of pleafure or pain, or by their af- fociation with other fibrous motions, as happens in our reveries or in fleep, there would (till appear to be fome difficulty in demonftrating the exiftence of any thing external to us. In our dreams we cannot determine this circumftance, be- caufe our power of volition is fufpended, and the ftimuli of ex- ternal objects are excluded ; but in our waking hours we can compare our ideas belonging to one fenfe with thofe belonging to another, and can thus diftinguifh the ideas occafioned by irrita- tion from thofe excited by fenfation, volition, or affociation. f the idea of the fweetnefs of fugar mould be excited in the v/birenefs and hardnefs of it occur at the fame time by aiTociation -, and we believe a material lump of fugar prchxit before u>. But if, in our waking hours, the iclea of the fweetnefs Sect. XIV. 3, OF IDEAS. ' 87 fweetnefs of fugar occurs to us, the ftimuli of furrounding ob- jects, as the edge of the table, on which we prefs, or green colour of the grafs, on which we tread, prevent the other ideas of the hardnefs and whitenefs of the fugar from being excited, by affociation. Or if they Ihould occur, we voluntarily com- pare them with the irritative ideas of the table or grafs above mentioned, and detect their fallacy. We can thus diftinguiih the ideas caufed by the ftimuli of external objects from thofe, which are introduced by aflbciation, fenfation, or volition ; and during our waking hours can thus acquire a knowledge of the external world. Which neverthelefs we cannot do in our dreams, becaufe we have neither perceptions of external bodies, nor the power of volition to enable us to compare them with the ideas of imagination. III. Of Vifion. Our eyes obferve a difference of colour, or of made, in the prominences and depreffions of objects, and that thofe (hades uniformly vary, when the fenfe of touch obferves any variation. Hence when the retina becomes ftimulated by colours or lhades of light in a certain form, as in a circular fpot •, we know by experience, that this is a fign, that a tangible body is before us ; and that its figure is refembled by the miniature figure of the part of the organ of vifion, that is thus ftimulated. Here whilft the ftimulated part of the retina refembles exact- ly the vifible figure of the whole in miniature, the various kinds of ftimuli from different colours mark the vifible figures of the minuter parts ; and by habit we inftantly recall the tangible figures. Thus when a tree is the object of fight, a part of the retina refembling a flat branching figure is ftimulated by various lhades of colours ; but it is by fuggeftion, that the gibbofity of the tree, and the mofs, that fringes its trunk, appear before us- Thefe are ideas of fuggeftion, which we feel or attend to, affo- ciated with the motions of the retina, or irritative ideas, which we do not attend to. So that though our vifible ideas refemble in miniature the outline of the figure of coloured bodies, in other reipects they ferve only as a language, which by acquired affociations intro- duce the tangible ideas of bodies. Hence it is, that this fenfe is fo readily deceived by the art of the painter to our amufe- ment and inftruction. The reader will find much -very curious knowledge on this fubjea in Bifhop Berkeley's May on Vifion, a work of great ingenuity. The U PRODUCTION G;:ct. XIV. j. The immediate object however of tlie fenfe of vifion is fight ; is fiuid, though its velocity is io great, appears to have no per- ceptible mechanical impnlfe, as was mentioned in the third Section, but feems to ftimuiate the retina into animal motion by its tranfmiflion through this part of the fenforium : for though the eyes of cats or other animals appear luminous in ob- fcure places ; yet it is probable, that none of the light, which falls on the retina, is reflected frf>m it, but adheres to or enters into combination with the choroide coat behind it. The combination of the particles of light with opaque bodies, and therefore with the choroide coat of the eye, is evinced from the heat which is given out, as in other chemical combinations. For the fun-beams communicate no heat in their paflage through tranfparent bodies, with which they do not combine, as the air continues cool even in the focus of the largefl burning-glafies, which in a moment vitrifies a particle of opaque matter. IV. Of the Organ of Hearing. It is generally believed, that the tympanum of the ear vi- brates mechanically, when expofed to audible founds, like the firings of one mutical inftrument, when the fame notes are ftruck upon another. Nor is this opinion improbable, as the mufcles and cartilages of the larinx are employed in producing variety of tones by mechanical vibration : fo the mufcles and bones of the ear feem adapted to increase or diminifh the ten- lion of the tympanum for the purpofes of iimilar mechanical vibration:. But it appears from di flection, that the tympanum is not the immediate organ of hearing, but that, like the humours and cor- nea of the eye, it is only of ufe to prepare the object for the immediate organ. For the portio mollis of the auditory nerve is not fpread upon the tympanum, but upon the vefcibulum, and cochlea, and iemi-circular canals of the ear ; while between the tympanum and the cxpanfion of the auditory nerve the cavity is faid by Dr. Cotunnus and Dr. Meehel to be filled with water ; as they had frequently obferved by freezing the heads of *\z?A animals before they difTecled them ; and water being a more denfe fluid than air is much better adapted to the propagation of vibrations. We may add, that even the external opening of the ear is not abfclutely neceflatfy for the perception of found . for forne people, who from thefe defects would have been com- pletely deaf, I ave diftuiguifhed acme or grave founds by the tre- mouTS of a flick held between their teerh propagated along the borfes of the head, (Haller Phyf T V. p. 295). lie nee Sect. XIV. 5, OF IDEAS. 89 Hence it appears, that the immediate organ of hearing is not affected by the particles of the air themfelves, but is ftimn- lated into animal motion by the vibrations of them. And it is probable from the loofe bones, which are found in the heads of fome fifties, that the vibrations of water are fenfible to the in- habitants of that element by a fimilar organ. The motions of the atmofphere, which we become acquainted with by the fenfe of touch, are combined with its folidity, weight, or vis inertiae ; whereas thofe, that are perceived by this organ, depend alone on its elafticity. But though the vi- bration of the air is the immediate object of the fenfe of hear- ing, yet the ideas, we receive by this fenfe, like thofe received from light, are only as a language, which by acquired affocia- tions acquaints us with thofe motions of tangible bodies, which depend on their elafticity ; and which we had before learned by our fenfe of touch. V. Of Smell and of Tafe. The objects of fmell are diflblved in the fluid atmofphere, and thofe of tafte in the faliva, or other aqueous fluid, for the better diffufing them on their refpective organs, which feem to be ftimulated into animal motion perhaps by the chemical af- finities of thefe particles, which conflitute the fapidity and odo- rofity of bodies, with the nerves of fenfe, which perceive them. Mr. Volta has lately obferved a curious circurnftance relative to our fenfe of tafte. If a bit of clean lead and a bit of clean filver be feparately applied to the tongue and palate no tafte is perceived ; but by applying them in contact in refpett to the parts out of the mouth, and nearly fo in refpect to the parts, which are immediately applied to the tongue and palate, a fa- line or acidulous tafte is perceived, as of a fluid like a ftrearn of electricity palling from one of them to the other. This new application of the fenfe of tafte deferves further inveftigation, as it may acquaint us with new properties of matter. From the experiments above mentioned of Galvani, Volta, Fowler, and others, it appears, that a plate of zinc and a plate of filver have greater effect than lead and filver. If one edge of a plate of filver about the fize of half a crown-piece be placed up- on the tongue, and one edge of a plate of zinc about the fame fize beneath the tongue, and if their oppofite edges are the-n brought into contact before the point of the tongue, a tafte is perceived at the moment of their coming into contact -, fecond- ly, if one of the above plates be put between the tipper lip and the gum of the fore-teeth, and the other be placed under the Vol. I. N tongu*. <>o PRODUCTION Sect. XIV. -6. tongue, and their exterior edges be then brought into contact in a darkim room, a flam of light is perceived in the eyes. Thefe effects I imagine only (hew the fenfibility of our nerves of fenfe to very fmall quantities of the electric fluid, as it pafles through them ; for I fuppofe thefe fenfations are occafioned by flight electric (hocks produced in the following manner. By the experiments publimed by Mr. Bennet, with his ingenious doubler of electricity, which is the greateft difcovery made in thatfcience fince the coated jar, and the eduction of lightning from the fkies, it appears that zinc was always found minus, and filver was always found plus, when both of them were in their feparate Itate. Hence, when they are placed in the man- ner above defcribed, as foon as their exterior edges come near- ly into contact, fo near as to have an extremely thin plate of air between them, that plate of air becomes charged in the fame manner as a plate of coated glafs 5 and is at the fame inftant difcharged through the nerves of tafle or of fight, and gives the fenfations, as above defcribed, of light or of faporofity ; and on- ly (hews the great fenfibility of thefe organs of fenfe to the ftim- ulus of the electric fluid in fuddenly paffing through them. VI. Of the Senfe of Heat. There are many experiments in chemical writers, that evince the exiftence of heat as a fluid element, which covers and per- vades all bodies, and is attracted by the folutions of fome of them, and is detruded from the combination of others. Thus from the combinations of metals with acids, and from thofc combinations of animal fluids, which are termed fecretions, this fluid matter of heat is given out amongft the neighbouring bod- ies ; and in the folutions of falts in water, or of water in air, it is abforbed from the bodies, that furround them ; whilfl in its facility in palling through metallic bodies, and its difficulty in pervading refins and glafs, it refembles the properties of the electric aura ; and is like that excited by friction, and feems like that to gravitate amongft other bodies in its uncombined flate, and to find its equilibrium. There is no circumftance of more confequence in the animal economy than a due proportion of this fluid of heat ; for the digeftion of our nutriment in the ftomach and bowels, and the proper qualities of all our fecreted fluids, as they are produced or prepared partly by animal and partly by chemical procefTcs, depend much on the quantity of heat ; the excefs of which, or its deficiency, alike gives us pain, and induces us to avoid the circumftances that occafion them. And in this the percep- tion Sect. XIV/6. OF IDEAS. 91 tion of heat eflentially differs from the perceptions of the fenfe of touch, as we receive pain from too great preflure of folid bodies, but none from the abfence of it. It is hence probable, that nature has provided us with a fet of nerves for the percep- tion of this fluid, which anatomifts have not yet attended to. There may be fome difficulty in the proof of this afTertion ; if we look at a hot fire, we experience no pain of the optic nerve, though the heat along with the light muft be concentra- ted upon it. Nor does warm water or warm oil poured into the ear give pain to the organ of hearing ; and hence as thefe organs of fenfe do not perceive fmall excefTes or deficiencies of heat ; and as heat has no greater analogy to the folidity or to the figures of bodies, than it has to their colours or vibrations ; there feems no fufficient reafon for our afcribing the perception of heat and cold to the fenfe of touch 5 to which it has gener- ally been attributed, either becaufe it is diffufed beneath the whole fkin like the fenfe of touch, or owing to the inaccuracy of our obfervations, or the defect of our languages. There is another circumftance would induce us to believe, that the perceptions of heat and cold do not belong to the or- gan of touch ; fince the teeth, which are the leaft adapted for the perceptions of folidity of figure, are the moft fenfible to heat or cold ; whence we are forewarned from fwallowing thofe mate- rials, whofe degree of coldnefs or of heat would injure our ftom- achs. The following is an extract from a letter of Dr. R. W. Dar- win, of Shrewfbury, when he was a ftudent at Edinburgh. " I made an experiment yefterday in our hofpital, which much fa- vours your opinion, that the fenfation of heat and of touch de- pend on different fets of nerves. A man who had lately recov- ered from a fever, and was ftill weak, was feized with violent cramps in his legs and feet ; which were removed by opiates, except that one of his feet remained infenfible. Mr. Ewart pricked him with a pin in five or fix places, and the patient de- clared he did not feel it in the leaft, nor was he fenfible of a very fmart pinch. I then held a red-hot poker at fome diftance, and brought it gradually nearer till it came within three inches, when he aflerted that he felt it quite diftinclly. I fuppofe fome violent irritation on the nerves of touch had caufed the cramps, and had left them paralytic ; while the nerves of heat, having fuffered no increafed flimulus, retained their irritability." Add to this, that the lungs, though eafily ftimulated into in- flammation, are not fenfible to heat. See Clafs III. 1. 1. 10. VII. Of 02 PRODUCTION Sect. XIV. 7, VII. Of the Senfe of Extetifon. The organ of touch is properly the fenfe of preflure, but the mufeuiar fibres themfelves conftitute the organ of fenfe, that feels extension. The fenfe of preflure is always attended with the ideas of the figure and folidity of the object, neither of which accompany our perception of extenfion. The whole fet of mufcles, whether they are hollow ones, as the heart, arteries, and ihtefthies, or longitudinal ones attached to bones, contract; themielves, whenever they are ftimulated by forcible elonga- tion ; and it is obfervable, that the white mufcles, which conftitute the arterial fyftem, feem to be excited into contrac- tion from no other kinds of ftimulus, according to the experi- ments of Haller. And hence the violent pain in fome inflam- mations, as in the paronychia, obtains immediate relief by cut- ting the membrane, that was ftretched by the tumour of the fubjacent parts. Hence the whole mufeuiar fyftem may be confidered as one organ of fenfe, and the various attitudes of the body, as ideas be- longing to this organ, of many of which we are hourly con- fcious, while many others, like the irritative ideas of the other fenfes, are performed without our attention. When the mufcles of the heart ceafe to act, the refluent blood again diftends or elongates them ; and thus irritated they contract as before. The fame happens to the arterial fyftem, and I fuppofe to the capillaries, inteftines, and various glands of the body. When the quantity of urine, or of excrement, diftends the bladder, or rectum, thofe parts contract, and exclude their con- tents, and many other mufcles by aflbciation act along with them ; but if thefe evacuations are not foon complied with, pain is produced by a little further extenfion of the mufeuiar fi- bres : a fimilar pain is caufed in the mufcles, when a limb is much extended for the reduction of diflocated bones ; and in tiie punifhment of the rack : and in the painful cramps of the calf of the legy or of other mufcles, for a greater degree of con- traction of a mufcle, than the movement of the two bones, to which its ends are affixed, will admit of, muft give fimilar pain to that, which is produced by extending it beyond its due length. And the pain from punctures or incifions arifes from the diftention of the fibres, as the knife pafles through them ; for it nearly ceafes as foon as the divifion is completed. All thefe motions of the mufcles, that are thus naturally ex- cited by the ftimulus of diftending bodies, are alfo liable to be called into ftrong action by their catenation with the irritations or Sect. XIV. 8- OF IDEAS. - 93 or fenfations produced by the momentum of the progrefTrve par- ticles of blood in the arteries, as in inflammatory fevers, or by acrid fubftances on other fenfible organs, as in the flrangury, or tenefmus, or cholera. We fliall conclude this account of the fenfe of extenfion by obferving, that the want of its object is attended with a difagree- able fenfation, as well as the excels of it. In thofe hollow muf- cles, which have been accuftomed to it, this difagreeable fenfa- tion is called faintnefs, emptinefs, and finking ; and, when it arifes to a certain degree, is attended with fyncope, or a total quiefcence of all motions, but the internal irritative ones, as happens from fudden lofs of blood, or in the operation of tap- ping in the dropfy. VIII. Of the Appetites of Hunger •, Thirf, Heat, Extenfion , the 10 ant of Frefh Air, Animal Love, and the Suckling of Children. Hunger is moil probably perceived by thofe numerous rami- fications of nerves that are fcen about the upper opening of the ftomach ; and thirft by the nerves about the fauces, and the top of the gula. The ideas of thefe fenfes are few in the generality of mankind, but are more numerous in thofe, who by difeafe, or indulgence, defire particular kinds of foods or liquids. A fenfe of heat has already been fpoken of, which may with propriety be called an appetite, as we painfully defire it, when it is deficient in quantity. The fenfe of extenfion may be ranked amongfl thefe appe- tites, fince the deficiency of its object, gives difagreeable fenfa- tion ; when this happens in the arterial fyftem, it is called faint- nefs, and feems to bear fome analogy to hunger and to cold ; which like it are attended with emptinefs of a part of the vafcu- lar fyftem. The fenfe of want of frefh air has not been attended to, but is as diftinct as the others, and the firft perhaps that we experi- ence after our nativity \ from the want of the object, of this fenfe many difeafes are produced, as the jail-fever, plague, and other epidemic maladies. Animal love is another appetite, which occurs later -in life, and the females of lactiferous animals have another natural inlet of pleafure or pain from the fuckling their offspring. The want of which, either owing to the death of their progeny, or to the fafhion of their country, has been fa- tal to many of the fex. The males have alfo pectoral glands, which are frequently turgid with a thin milk at their nativity, and are furnifhed with nipples, which erect on titillation like thofe of the female j but which feem now to be of no further ufc, 94 PRODUCTION, &c- Sect. XIV. 9: ufe, owing perhaps to fome change which thefe animals have undergone in the gradual progreflion of the formation of the earth, and of all that it inhabit. Thefe feven laft mentioned fenfes may properly be termed appetites, as they differ from thofe of touch, fight, hearing, tafte, and fmell, in this refpect ; that they are affected with pain as well by the defect of their objects as by the excefs of them, which is not fo in the latter. Thus cold and hunger give us pain, as well as an excefs of heat or fatiety ; but it is not fo with darknefs and filence. IX. Before we conclude this Section on the organs of fenfe, we muft obferve, that, as far as we know, there are many more fenfes than have been here mentioned, as every gland feems to be influenced to feparate from the blood, or to abforb from the cavities of the body, or from the atmofphere, its appropriated fluid, by the ftimulus of that fluid on the living gland ; and not by mechanical capillary abforption, nor by chemical affinity. Hence it appears, that each of thefe glands muft have a peculiar organ to perceive thefe irritations, but as thefe irritations are not fucceeded by fenfation, they have not acquired the names of fenfes. However when thefe glands are excited into motions ftronger than ufual, either by the acrimony of their fluids, or by their own irritability being much increafed, then the fenfation of pain is produced in them as in all the other fenfes of the body ; and thefe pains are all of different kinds, and hence the glands at this time really become each a different organ of fenfe, though thefe different kinds of pain have acquired no names. Thus a great excefs of light does not give the idea of light but of pain ; as in forcibly opening the eye when it is much infla- med. The great excefs of preffure or diftention, as when the point of a pin is preffed upon our fkin, produces pain, (and when this pain of the (tnfc of diftention is ilighter, it is termed itch- ing, or tickling), without any idea of folidity or of figure : an excefs of heat produces fmarting, pf cold another kind of pain ; it is probable by this fenfe of heat the pain produced by cauftic "bodies is perceived, and of electricity, as all thefe are fluids, that permeate, diftend, or decompofe the parts that feel them. SECT. Sect. XV. i. l. CLASSES OF IDEAS. 95 SECT. XV. OF THE CLASSES OF IDEAS. I. I. Ideas received in tribes. 2. We combine them further, or ab- filracl from thefe tribes. 3. Complex ideas. 4. Compounded ideas. C. Simple ideas , modes , fubjlances , relations , general ideas, 6. Ideas of reflexion. *]. Memory and imagination imperfeclly defined. Ideal prefence. Memorandum-rings. II. 1. Irrita- tive ideas. Perception. 2. Senftive ideas, imagination. 3. Voluntary ideas, recolleclion. 4. AJfociated ideas, fuggefiion. III. 1. Definitions of perception, memory. 2. Reafoning, judge- ment, doubting, dijhnguiffjing, comparing. 3. Invention. 4. Confcioufnefs. 5. lndentity. 6. Lapfe of time. 7. Freewill. I. 1. As the conftituent elements of the material world are only perceptible to our organs of fenfe in a ftate of combination j it follows, that the ideas or fenfual motions excited by them, are* jiever received fingly, but ever with a greater or lefs degree of combination. So the colours of bodies or their hardneSes oc- cur with their figures : every fmell and tafte has its degree of pungency as well as its peculiar flavour : and each note in muiic is combined with the tone of fome inftrument. It appears from hence, that we can be fenfible of a number of ideas at the fame time, fuch as the whitenefs, hardnefs, and coldnefs of a fnow- bafl, and can experience at the fame time many irritative ideas of furrounding bodies, which we do not attend to, as mentioned in Section VII. 3. 2. But thofe ideas which belong to the fame fenfe, feem to be more eafily combined into fynchronous tribes, than thofe which were not received by the fame fenfe, as we can more eafily think of the whitenefs and figure of a lump of fugar at the fame time, than the whitenefs and fweetnefs of it. 2. As thefe ideas, or fenfual motions, are thus excited with greater or lefs degrees of combination ; fo we have a power, when we repeat them either by our volition or fenfation, to in- creafe or diminifli this degree of combination, that is, to form compounded ideas from thofe, which were more fimple j and ab- ftracl: ones from thofe, which were more complex, when they were firft excited j that is, we can repeat a part or the whole of thofe fenfual motions, which did conftitute our ideas of percep- tion ; and the repetition of which now conftitutes our ideas ©f recolleclion, or of imagination. 3. Thofe ideas, which we repeat without change of the quan- tity of that combination, with which we firft received them, are called 9S CLASSES OF IDEAS. Sect. XV. i. 4. called complex ideas, as when you recollect Weftminfter Ab- bey, or the planet Saturn : but it muft be obferved, that thefe complex ideas, thus re-excited by volition, fenfation, or affocia- tion, are feldom perfect copies of their correfpondent percep- tions, except in our dreams, where other external objects do not detract our attention. 4. Thofe ideas, which are more complex than the natural ob- jects that iirft excited them, have been called compounded ideas, as when we think of a fphinx, cr griffin. 5. And thofe that are lefs complex than the correfpondent natural objects, have been termed abftracled ideas : thus fweet- nefs, and whitened, and folidity, are received at the fame time from a lump of fugar, yet I can recollect any of thefe qualities without thinking of the others, that were excited along with them. See Sect. XVI. 1 7. When ideas are fo far abftracted as in the above example, they have been termed fimple by the writers of metaphyfics, and feem indeed to be more complete repetitions of the ideas or fen- fual motions, originally excited by external objects. Other claiTes of thefe ideas, where the abftraction has not been fo great, have been termed, by Mr. Locke, modes, fubftances, and relations, but they feem only to differ in their degree of ab- itraction from the complex ideas that were at firft excited ; for as thefe complex or natural ideas are themfelves imperfect copies of their correfpondent perceptions, fo thefe abftract or general ideas are only (till more imperfect copies of the fame percep- tions. Thus when I have feen an object but once, as a rhinoce- ros, my abitract idea of this animal is the fame as my complex one. I may think more or lefs diflinctly of a rhinoceros, but it is the very rhinoceros that I faw, or fome part or property of him, which recurs to my mind. But when any clafs of complex objects becomes the fubject of converfation, of which I have icen many individuals, as a caftle or an army, fome property or circumftance belonging to it is peculiarly alluded to ; and then I feel in my own mind, that my abitract idea of this complex object is only an idea of that part, property, or attitude of it, that employs the prefent converfation, and varies v/ith every ferrtence that is fpoken concerning it. So if any one mould fay, " one may fit upon a horfe fafer than on a camel," my abstract idea of the two animals includes only an outline of the level back of the one, and the gibbofity on the back of the other. What noifc is that in the ftreet ? — J horfes trotting over the pavement. Her? my idea of the horl includes principally the mape and motion of their legs. alfo • ore im- C '"V Sect. XV. i. 6. GLASSES GF IDEAS, 9* perfect reprefentations of the objects they were received from ; for here we abftract the material parts, and recoil eel: only the qualities. Thus we abftract fo much from fome of our complex ideas* that at length it becomes difficult to determine of what percep- tion they partake ; and in many inftances our idea feems to be no other than of the found or letters of the word, that ftands for the collective tribe, of which we are faid to have an abftracted idea, as noun, verb, chimaera, apparition. Mr. Home Tooke alfo, in his Diverfiohs of Purley, has very ingenioufly (hewn, that what were called general ideas, are iri reality only general terms ; or words which fignify any part3 of a complex object. Whence arifes much error in our verbal reafoning, as the fame word has different fignifxeations. And hence thofe, who can think without words, reafon more accu- rately than thofe, who only compare the ideas fuggefted by words ; a rare faculty, which diftinguifhes the writers of phi- lofophy from thofe of fophiftry. See Clafs III. 2. 2. 3. 6. Ideas have been divided into thofe of perception and thofe of reflection, but as whatever is perceived muft be external td the organ that perceiyes it, all our ideas muit originally oe ideas of perception. 7. Others have divided our ideas into thofe of memory and thofe of imagination 5 they have faid that a recollection of ideas in the order they were received conftitutes memory, and with- out that order imagination •, but all the ideas of imagination, ex- cepting the few that are termed fimple ideas, are parts of trains or tribes in the order they were received j as if I think of a fphinx, or a griffin, the fair face, befom, wings, claws, tail, are all complex ideas in the order they were received : and it be- hoves the writers, who adhere to this definition, to determine, how fmall the trains muft be* that fhall be called imagination j and how great thofe, that fhall be called memory. Others have thought that the ideas of memory have a greater toivacity than thofe of imagination : but the ideas of a perlbn in fleep, or in a waking reverie, where the trains connected with fenfation are uninterrupted, are more vivid and diftinct than thofe of memory, fo that they cannot be diflinguiflied by this criterion. The very ingenious author of the Elements of Criticifra has defcribed what he conceives to be a fpecies of memory, and call? it ideal prefence ; but the inftances he produces are the reveries of ienfation, and are therefore in truth connexions of the imag- ination, though they are recalled iri the order they were received , Fae ideas connected by aflbciation are in common difcourfe Vol. I, O attribtoteel 93 CLASSES OF IDEAS. Sect. XV. 2. u attributed to memory, as we talk of memorandum-rings, and tie a knot on our handkerchiefs to brhig fomething into our minds at a dillance of time. And a fchool-boy who can repeat a thoufand unmeaning lines in Lilly's Grammar, is faid to have a good memory. But thefe have been already (hewn to belong to the clafs of affociation ; and are termed ideas of fuggeftion. II. Laftly, the method already -plained of claffing ideas into thofe excited by irritation, fenfation, volition, or affociation, wc hope will be found more convenient both for explaining the operations of the mind, and for comparing them with thofe of the body ; and for the illuftration and the cure of the difeafes of both, and which we {hall here recapitulate. 1. Irritative ideas are thofe, which are preceded by irritation, which is excited by objects external to the organs of fenfe : as the idea of that tree, which either I attend to, or which I fhun in walking near it without attention. In the former cafe it is termed perception, in the latter it is termed fimply an irritative idea. 2. Senfitive ideas are thofe, which are preceded by the fen- fation of pleafure or pain ; as the ideas, which conftitute our dreams or reveries, this is called imagination. 3. Voluntary ideas are thofe, which are preceded by voluntary exertion, as when I repeat the alphabet backwards : this is call- ed recollection. 4. AiTociate ideas are thofe, which are preceded by other ideas or mufcular motions, as when we think over or repeat the alphabet by rote in its ufual order ; or fing a tune we are accuf- tomed to ; this is called fuggeftion. III. 1 . Perceptions fignify thofe ideas, which are preceded by irritation and fucceeded by the fenfation of pleafure or pain, for whatever excites our attention interefts us ; that is, it is ac- companied with pleafure or pain ; however flight may be the degree or quantity of either of them. The word memory includes two clafTes of ideas, either thofe which are preceded by voluntary exertion, or thofe which are fuggefled by their affociations with other ideas. 2. Reafoning is that operation of the fenforium, by which we excite two or many tribes of ideas ; and then re-excite the ideas, in which they differ, or correfpond. If we determine this differ- ence, it is called judgment; if we in vain endeavour to deter- mine it, it is called doubting. If wc re-excited the ideas, in which they differ, it is called diftinguifhing. If we re-excite thofe in which they correfpond, it is called comparing. Invention is an operation of the fenforium, by which we voluntarily Sect. XV. 3.4. CLASSES OF IDEAS. 99 voluntarily continue to excite one train of ideas, fuppofe the de- fign of railing water by a machine 5 and at the fame time attend to all other ideas, which are connected with this by every kind of catenation ; and combine or feparate them voluntarily for the purpofe of obtaining fome end. For we can create nothing new, we can only combine or fepa- rate the ideas, which we have already received by our percep- tions : thus if I wilh to reprefent a monfter, I call to my mind the ideas of every thing difagreeable and horrible, and combine the naftinefs and gluttony of a hog, the ftupidity and obftinacy of an afs, with the fur and awkwardnefs of a bear, and call the new combination Caliban. Yet fuch a monfter may exifl in nature, as all his attributes are parts of nature. So when I wim to reprefent every thing, that is excellent and amiable ; when I combine benevolence with cheerfulnefs, wifdom, knowledge, tafte, wit, beauty of perfon, and elegance of manners, and ailb- ciate them in one lady as a pattern to the world, it is called in- vention j yet fuch a perfon may exift, — fuch a perfon does ex- ift ! — It is — , who is as much a monfter as Caliban. 4. In refpecl: to confeioufnefs, we are only confeious of our exiftence, when we think about it ; as we only perceive the lapfe of time, when we attend to it ; when we are bufied about other objects, neither the lapfe of time nor the confeioufnefs of our own exiftence can occupy our attention. Hence, when we think of our own exiftence, we only excite abftracted or reflex ideas (as they are termed), of our principal pleafures or pains, of our defires or averfions, or of the figure, folidity, colour, or other properties of our bodies, and call that acl: of the fenfori- ura a* confeioufnefs of our exiftence. Some philofophers, I be- lieve it is Des Cartes, has faid, « I think, therefore I exift. " But this is not right reafoning, becaufe thinking is a mode of exiftence ; and it is thence only faying, " I exift, therefore I exift." For there are three modes of exiftence, or in the lan- guage of grammarians three kinds of verbs. Firft, fimpiy I am, or exift. Secondly, I am a&ing, or exift in a ftate of activity, as I move. Thirdly, I am fuffering, or exift in a ftate of being a£ted upon, as I am moved. The when, and the where, as ap- plicable to this exiftence, depends on the fucceflive motions of our own or of other bodies ; and on their refpective fituations, as fpoken of, Seel. XIV. 2.5. 5. Our identity is known by our acquired habits or catenated trains of ideas and mufcular motions ; and perhaps, when we compare infancy with old age, in thofe alone can. our identity be fuppofed to exift. For what elfe is there of fimilitude between the firft fpeck of living entity and the mature man .p— every de- dudliort }co CLASSES OF IDEAS. Sect. XVs. 3. 6, fluction of reafoning, every fentiment or paflion, with eVery fibre of the corporeal part of our fyftem, has been fubjecl: almoit to annual mutation ; while fome catenations alone of our ideas and mufcular actions have continued in part unchanged. By the facility, with which we can in our waking hours vol- untarily produce certain fucceflive trains of ideas, we know by experience, that we have before reproduced them ; that is, we are conlcious of a time of our exiftence previous to the prefent rime -, that is, of our identity now and heretofore. It is thefe habits oi action, thefe catenations of ideas and mufcular mo- $ion$, which begin with life, and only terminate with it ; and which we can in fome meafure deliver to our pollerity ; as ex- plained in Sc£t. XXXIX. 6. When the progreflive motions of external bodies make a part of our prefen: catenation of ideas, we attend to the lapfeof tiiiie ; which appears the longer, the more frequently we thus attend to it ; as when we expect fomething at a certain hour, which much interefts us, whether it be an agreeable or difagree- able event -, cr when we count the paffing feconds oh a ftop- watch. When an idea of our own perfon, or a reflex idea of our pleufurec and pains, defires and averfions, makes a part of this catenation, it is termed confcioufnefs ; and if this idea of con. fcioufnefs makes a part of a catenation, which we excite by rec- ollection, and know by the facility with which we excite it, that we have before experienced it, it is called identity, as explained above, 7. In refpect to freewill, it is certain, that we cannot will to think of a new train of ideas, without previoufly thinking of the iirfl: link of it ; as I cannot will to think of a black fwan, with- out previoufly thinking of a black fwan. But if I now think of a tail, I can voluntarily recollect all animals, which have tails j my will is fo far free, that I can purfue the ideas linked to this idea of tail, as far as my knowledge of the fubjecl: extends •, but to will without motive is to will without defire or averfion ; which is as abfurd as to feel without pleafure or pain ; they are both folecifms in the terms. So far are we governed by the catenations of motions, which affect: both the body and the mind of man^ and which begin with our irritability, and end with it. SECT. Sect. XVI. u OF INSTINCT. iof SECT. XVL OF INSTINCT. HAUD EQUIDEM CREDO, qUlA SIT DIVIN1TUS ILL1S INGENIUM, AUT RERUM FATO PRUDENTIA MAJOR. VIRG. GEORG. L. I. 415. I. InfiinElive atlions defined. Of connate pafiions. II. Of the fen* fations and motions of the foetus in the womb. III. Some animals are more perfeclly formed than others before nativity. Of learn- ingto walk. IV. Of the /wallowing, breathing, /ticking, pecking, and lapping of young animals. V. Of the fenfe of/nell, and its ufes to animals. Why cats do not eat their kittens* VI. Of the accuracy of fight in mankind \ and their fienje of beauty. Of the fenfe of touch in elephants •, monkies, beavers, men. VII. Of nat- ural language. VIII. The origin of natural language ; I . the language of fear ; 2. of grief ; 3. of tender pleafure ,- 4. offe- rene pie of tire ; 5. of anger ; 6 .jf attention. IX. Artificial lan- guage of turkies, hens, ducklings, wagtails, cuckoos, rabbits, dogsy and nightingales. X. Ofmufic; of tooth- edge ; of a good ear ; of ar chit eel ure. XI. Of acquired knowledge; of foxes, rooks f fieldfares, lapwings, dogs, cats, horfes, crows, pelicans, the tiger , and rattlefnake. XII. Of birds of pajfage, dormice, fnakes, bats3 fwallows, quails, ring-doves, the flare, chaffinch, hoopoe, chatterer, hawfinch, cro/s-bill, rails and cranes. XIII. Of birds' nefis ; of the cuckoo ; of '/wallows' nefis ; of the t ay lor bird. XIV. Of the old/oldier-i of haddocks, ceds, and dog-fi/h ; of the remora ; of crabs, herrings, and/almon. XV. Of/piders, caterpillars, ants% and the ichneumon. XVI. 1. Of locufis, gnats ; 2. bees ; 3. dormice, flies, worms, ants, and wa/ps. XVII. Of the faculty that difiinguifioes man from the brutes. I. All thofe internal motions of animal bodies, which con- tribute to digeft their aliment, produce their fecretions, repair their injuries, or increafe their growth, are performed without our attention or confeioufnefs. They exift as well in our fleep, as in our waking hours, as well in the fetus during the time of geftation, as in the infant after nativity, and proceed with equal regularity in the vegetable as in the animal fyilem. Thefe motions have been (hewn in a former part of this work to de- pend on the irritations of peculiar fluids, and as they have never been ciaffed amongft the inftinftive actions of animals, are pre- cluded from our prefent difquifitior.- Bt 102 OF INSTINCT. Sect. XVI. 2: But all thofe anions of men or animals, that are attended •with conicioufnefs, and feem neither to have been directed by their appetites, taught by their experience, nor deduced from ob- fervation or tradition, have been referred to the power of in- ftinct. And this power has been explained to be a divine fome- ihing, a kind of infpiration ; whiiil the poor animal, that poiTerT- es it, has been thought little better than a machine ! The irkfomenefsy that attends a continued attitude of the body, or the pains, that we receive from heat, cold, hunger, or other injurious circumflances, excite us to general locomotion : and our fenies are fo formed and conftituted by the hand of nature, that certain objects prefent us with pleasure, others with pain, and we are induced to approach and embrace thefe, to avoid and abhor thofe, as fuch fenfations direct us. Thus the palates of fome animals are gratefully affected by the maftication of fruits, others of grains, and others of flelh ; and they are thence inftigated to attain, and confume thofe ma- terials ', and are furniihed with powers of mufcular motion, and of digeflion proper for fuch purpofes. Thefe fenfations and defires conftitute a part of our fyftem, as cur mufcles and bones conftitute another part : and hence they may alike be termed natural ox connate „• but neither of them can properly be termed inftinctive : as the word inftinct in its ufual acceptation refers only to the aclions of animals, as above ex- .imed : the origin of thefe actions is the fubject of our prefent inquiry. The reader is entreated carefully to attend to this definition cf injlintlive a6lions, left by ufing the word inftinct without ad- joining any accurate idea to it, he may not only include the nat- ural defires of love and hunger, and the natural fenfations of pain or pleafure, but the figure and contexture of the body, and the faculty of reafon itfelf, under this general term. II. We experience fome fenfations, and perform fome ac- tions before our nativity \ the fenfations of cold and warmth, agitation and reft, fulnefs and inanition, are inftances of the former ; and the repeated druggies of the limbs of the foetus, which begin about the middle of geftation, and thofe motions by which it frequently wraps the umbilical chord around its neck or body, and even fometimes ties it in a knot ; are inftan- ces of the latter. (Smeliie's Midwifery, Vol. I. p. 182.) By a due attention to thefe circumflances many of the ac- tions of young animals, which at firft fight feemed only referable to an inexplicable inftinct, will appear to have been acquired like all other animal actions,, that are attended with confeioufnefs, OK Sect. XVI. 3. OF INSTINCT. 103 by the repeated efforts of our mufcles under the conduft cf our fenja* tions or de/ires. The chick in the fhell begins to move its feet and legs oa the fixth day of incubation (Mattreican, p. 138)5 or on the feventh day, (Langley) j afterwards it is feen to move itfeif gently in the liquid that {unrounds it, and to open and (hut its mouth, (Harvei, de Generat. p. 62, and 197. Form, de Poulet, ii. p. 129). Puppies before the membranes are broken, that involve them, are feen to move themfelves, to put out their tongues, and to open and fhut their mouths, (Harvey, Gipfcn, Riolan, Haller). And calves lick themfelves and fwallow many of their hairs before their nativity, which however puppies do not, (Swammerdam, p. 3 19. Flemyng Phil. Tranf. Ann. 1755* 42). And towards the end of geftation, the fcetufes of all ani- mals are proved to drink part of the liquid in which they fwim3 (Haller. Phyfiol. T. 8. 204). The white of egg is found in the mouth and gizzard of the chick, and is nearly or quite confumed before it is hatched, (Harvei de Generat. $8). And the liquor amnii is found in the mouth and ftomach of the human foetus, and of calves ; and how elfe fhould that excrement be produced in the interlines of all animals, which is voided 1a great quantity foon after their birth ; (Gipfon Med. Effays, Edinb. V. i. 13. Halleri Phyfiolog. T. 3. p. 318. and T. 8.) In the ftomach of a calf the quantity of this liquid amounted to about three pints, and the hairs amongit it were of the fame col- our with thofe on its fkin, (Blafii Anat. Animal, p. m. 122), Thefe facts are attefted by many other writers of credit, befides tho.fe above mentioned. III. It has been deemed a furprifing inftance of mftinct, that calves and chickens fhould be able to walk by a few efforts al- moft immediately after their nativity : whilil the human infant in thofe countries where he is not encumbered with clothes, as in India, is five or fix months, and in our climate almoil a twelvemonth, before he can fafely fland upon his feet. The ftruggles of all animals in the womb muft refemble their mode of fwimminp, as bv this kind of motion thev can bell change their attitude in water. But the fwimming of the calf and chicken refembles their manner of walking, which thev have thus in part acquired before their nativity, and hence accompiifh it afterwards with very few efforts, whilft the fwimming of the human creature refembles that of the frog, and totally differs from his mode of walking. There is another circumftance to be attended to in this affair, that not only the growth of thofe peculiar parts of anim which are firft wanted to fecure their fubijyjence, are in general fartheft io4 OF INSTINCT. Sect. XVL 4. furtheit advanced before their nativity : but fome animals come into the world more completely formed throughout their whole fyflem them others ; and are thence much forwarder in all their habits of morion. Thus the colt, and the lamb, are much more perfect animals than die blind puppy, and the naked rabbit ; an.i the chick of the pheafant, and the partridge, has more perfect plumage, and more perfect eyes, as well as greater aptitude to locomotion, than the callow nefllings of the dove, and of the wren. The parents of the former only find it neceffary to (hew them their food, and teach them to take it up ; whilft thofe of the latter are obliged for many days to obtrude it into their gaping mouths. IV. From the facto mentioned in No. 2. of this Section, it is evinced that the foetus learns to fwallow before its nativity ; for it is feen to open its mouth, and its flomach is found filled with the liquid that furrounds it. It opens its mouth, cither inftigated by hunger, or by the irkfomenefs of a continued at- titude of the mufcles of its face ; the liquor amnii, in which it fvvims, is agreeable to its palate, as it confifls of a nouri filing material, (Ilaller. Phyf. T. o. p. 204). It is tempted to expe- rience its talte further in the mouth, and by a few efforts learns to fwallow, in the fame manner as we learn all other animal ac- • ns, which are attended with coufcioumefs, by the repeated ef- forts of cur mufcles wilder the conducl of our fenfaikns or volitions. The infpiration of air into the lungs is io totally different from that of fwaliowing a fluid in which we are immerfed, that it cannot be acquired before our nativity. But at this time, when the circulation of the blood is no longer continued through e placenta, that fuftocating ienfation, which wre feci about the precordia, when we are in want of frefli air, difagreeably af- fects the infant : and all the mufcles of the body are excited into action to relieve this opprefTion ; thofe of the bread, ribj, and diaphragm are found to anfwer this purpofe, and thus ref piration is difepvered, and is continued throughout our lives, as often as the opprefTion begins to recur. Many infants, both of the human creature, and of quadrupeds, ftruggle for a minute after they are born before they begin to breathe, (Ilaller. Phyf. T. 8. p. 400. ib. pt. 2. p. 1). Mr. BufFcn thinks the action of tl I dry air upon the nerves of fmell of new-born animals, by pro- ducing an endeavour to fneeze, may contribute to induce tl firft infpiration, and that the rarefaction of the air by the warmth of the lungs contributes to induce exptiation, (Hill- Nat. Tom. 4. p. 174). Which latter it may effect: by produ- . r.'mg a difagrecuble fenfation bv its delays and 1 :onfequenf Sect. XVI. 5. 1. OF INSTINCT, io| fort to relieve it. Many children fneeze before they refpire, but not all, as far as I have obferved, or can learn from others. At length, by the direction of its fenfe of fmell, or by the offi- cious care of its mother, the young animal approaches the odo- riferous rill of its future nourishment, already experienced to f wallow. But in the a£t of fwallowiilg, it is necetTary nearly to clofe the mouth, whether the creature be immerfed in the fluid it is about to drink, or not : hence, when the child firft attempts to fuck, it does not (lightly comprefs the nipple between its lips, and fuck as an adult perfon would do, by abforbing the milk 5 but it takes the whole nipple into its mouth for this purpofe, comprefTesit between its gums, and thus repeatedly chewing (as it were) the nipple, preiTes out the milk ; exactly in the fame manner as it is drawn from the teats of cows by the hands o£ the milkmaid. The celebrated Harvey obferves, that the foetus in the womb muft have fucked in a part of its nourifnrnent, be- caufe it knows how to fuck the minute it is born, as any one may experience by putting a finger between its lips, and becaufe in a few days it forgets this art of fucking, and cannot without fome difficulty again acquire it, (Exercit. de Gener. Anim. 4S). The fame obfervation is made by Hippocrates. A little further experience teaches the young animal to fuck by abforption, as well as by qpmpreGion 5 that is, to open the cheft as in the beginning of refpiration, and thus to rarefy the air in the mouth, that the prefTure of the denfer external atmos- phere may contribute to force out the milk. The chick yet in the (hell has learnt to drink by fwallowing a part of the white of the e^g for its food 5 but not having ex- perienced how to take up and fwallow folid feeds, or grains, is either taught by the folicitous induftry of its mother ; or by many repeated attempts is enabled at length to diftinguiih and to fwallow this kind of nutriment. And puppies, though they know how to fuck like other ani- mals from their previous experience in fwallowing, and in ref- piration ; yet are they long in acquiring the art of lapping with their tongues, which from the flaccidity pi their cheeks, and length of their mouths, is afterwards a more convenient way for them to take in water. V. The fenfes of fmell and tafte in many other animals greatly excel thofe of mankind, for in civilized fociety, as our victuals are generally prepared by others, and are adulterated with fait, fpice, oil, and empyreuma, we do not hefitate ab eating whatever is fet before us, and negledt to cultivate thefe fenfes : whereas other animals try every morfel by the fmell, be- fore they take it into their mouths, and by the tafte before they Vol. I. P fwallow io6. , OF INSTINCT. Sect. XVI. 6. i, IVallow it ; and are led not only each to his proper nourifhmenfc by thjs organ of fenfe, but it alfo at a maturer age directs them in the gratification of their appetite of love. Which may be further underftood by confidering the fympathies of thefe parts defcribed in clafs IV. 2. 1.7. While the human animal is di- rected to the object of his love by his fenfe of beauty, as men- tioned in No. VI. of this Section. Thus Virgil Georg. III. 250. Nonne vides, ut tota tremor pertentat equorum Corpora, fi tantura notas odor attulit auras? Nonne canis nidum veneris mfutus odore Qusrit, et erranti trahitur fublambere lingua ? Refpuit at guftum cupidus, labiifque retra&is £levat os, trepidanfque r.ovis impellitur 2iftri3 Inferit et vivum felici vomere femen. — Quam tenui filo cascos adnectit amores Docla Venus, vitsEque monet renovare favillam ! An'on. The following curious experiment is related by Galen. « On directing a goat great with young I found a brilk embryon, and having detached it from the matrix, and fnatching it away be- fore it faw its dam, I brought it into a certain room, where there were many velTels, fome filled with wine, others with oil, fome with honey, others with milk, or fome other liquor ; and in others were grains and fruits ; we firfl obferved the young animal get upon its feet, and walk ; then it fhook itfelf, and af- terwa/ds fcratched its fide with one of its feet : then we faw it fmelling to every one of thefe things, that were fet in the room ; and when it had fmclt to them all, it drank up the milk." L. 6. de locis. cap. 6. Parturient quadrupeds, as cats, and bitches, and fows, arc led by their fenfe of fmell to eat the placenta as other common food •, why then do they not devour their whole progeny, as is reprefented in an ancient emblem of Time ? This is laid fome- times to happen in the unnatural ftate in which we confine fows ; and indeed nature would feem to have endangered her offspring in this nice circumftance ! But at this time the ftimu- lus of the milk in the tumid teats of the mother excites her to look out for, and to defire fome unknown circumftance to re- lieve her. At the fame time the fmell of the milk attracts the exertions of the young animals towards its fource, and thus the delighted moiher difcovers a new appetite, as mentioned in Sec"t. XIV. 8. and her little progeny are led to receive and to communicate pleafure by this moll beautiful contrivance. VI. But though the human fpecies in fome of their fenfa- tions are much inferior to other animals, yet the accuracy of the fenfe/ Sect. XVI. 6. i. OF INSTINCT. 107 fenfe of touch, which they pofTefs in fo eminent a' degree, gives them a great iuperiority of underftanding -, as is well obferved by the ingenious Mr. BufFon. The extremities of other animals terminate in horns, and hoofs, and claws, very unfit for the fen- fation of touch ; whilfl the human hand is finely adapted tc en- compafs its object with this organ of fenfe. The elephant is indeed endued with a fine fenfe of feeling at the extremity of his probofcis, and hence has acquired much more accurate ideas of touch and of fight than molt other crea- tures. The two following inftances of the fagacity of thefe an- imals may entertain the reader, as they were told me by fome gentlemen of diftinct obfervation, and undoubted veracity, who had been much converfant with our eaftern lettlements. Firft, the elephants that are ufed to carry the baggage of our armies, are put each under the care of one of the natives of Indofian^ and whiift himfelf and his wife go into the woods to collect, leaves and branches of trees for his food, they fix him to the ground by a length of chain, and frequently leave a child yet unable to walk, under his protection : and the intelligent animal not only defends it, but as it creeps about, when it arrives near the ex- tremity of his chain, he wraps his trunk gently round its body, and brings it again into the centre of his circle. Secondly, the traitor elephants are taught to walk on a narrow path between two pit- falls, which are covered with turf, and then to go into the woods, and to feduce the wild elephants to come that way, who fall into thefe well ;, whiift he pafTes fafe between them : and it is univerfally obferved, that thofe wild elephants that ef- cape the fnare, purfue the traitor with the utmoft vehemence, and if they can overtake him, which fometimes happens, they always beat him to death. The monkey has a hand well enough adapted for the fenfe of touch, which contributes to his great facility of imitation ; but in taking objecls with his hands, as a flick or an apple, he puts his thumb on the fame fide of them with his fingers, inftead of counteracting the preflure of his fingers with it : from this neg- lect he is much ilower in acquiring the figures of objects, as he is lefs able to determine the diftances or diameters of their parts, or to diftinguifh their vis inertise from their hardnefs. Helve- tius adds, that the Ihortnefs of his life, his being fugitive be- fore mankind, and his not inhabiting all climates, combine to prevent his improvement. (De l'Efprit. T. 1. p.) There is however at this time an old monkey (hewn in Exeter Change^ London, who having loft his teeth, when nuts are given him, takes a ft one into his hand, and cracks them with it one by oik- ; thus tiimg tools to effeft his purpofe like mankind. The jo8 OF INSTINCT. Sect. XVI. 6. u The beaver is another animal that makes much ufe of his hands, and if we may credit the reports of travellers, is pofTefTed of amazing ingenuity. This however, M. BufTon affirms, is on- ly where they exift in large numbers, and in countries thinly peopled with men ; while in France in their folitary ftate they fhew no uncommon ingenuity. Indeed all the quadrupeds, that have collar-bones, (clavicular) ufe their foie-limbs in fome meafure as we ufe our hands, as the cat, fquirrel, tyger, bear and lion ; and as they exercife the fenfe of touch more univerfally than other animals, fo are they more fagacious in watching and furprifing their prey. All thofe birds, that ufe their claws for hands, as the hawk, parrot, and cuckoo, appear to be more docile and intelligent ; though the gregarious tribes of birds have more acquired knowledge. Now as the images, that are painted on the retina of the eye, are no other than figns, which recall to our imaginations the ob- jects we had before examined by the organ of touch, as is fully demonftrated by Dr. Berkeley in his treatife on vifion ; it follows that the human creature has greatly more accurate and diftincT fenfe of vifion than that of any other animal. Whence as he advances to maturity he gradually acquires a fenfe of female beauty, which at this time directs him to the object of his new paflion. Sentimental love, as diftinguifhed from the animal paflion of that name, with which it is frequently accompanied, confifts in the defire or fenfation of beholding, embracing, and faluting a beautiful object. The characleriftic of beauty therefore is that it is the object of love : and though many other objects are in common language called beautiful, yet they are only called fo metaphorically, and ought to be termed agreeable. A Grecian temple may give us the pleafurable icica of fublimity, a Gothic temple may give us the pleafurable idea of variety, and a modern hdufe the pleafur- able idea of utility j muflc and poetry may infpire our love by aifociation of ideas ; but none of thefe, except metaphorically, can be termed beautiful ; as we have no wilh to embrace or fa- lute them. v ur perception of beauty confifts in our recognition by the fenfe of viiion of thofe objects, firft, which have before infpired our love by the pleafure, which they have afforded to many of our fenfes : as to our f.nfe of warmth, of touch, of fmell, of fte, hunger and thirft ; and, fecondly, which bear any analo- gy of form to fuch objects. When the babe, focn after it is born into this cold world, is applied to its rr vomiting are -thus propa- gated by fympathy, and fome people of delicate fibres, at the prefence of a fpectacle of mifery, have felt pain in the fame parts of their own bodies, that were difealed or mangled in the o:her. Amongft the writers of antiquity Ariftotlc thought this aptitude to imitation an eiTential property of the human fpecies, 2nd calls man an imitative animal. To fyw {upupiw. Thefe then are the natural figns by which we underftand each her, and on this flender bafij is built all human language. For without fome natural figns, no artificial ones could have been invented or underftood, as is very ingenioufly obferved by Dr. id, (Inquiry into the Human Mind.) VIII. The origin of this urtiverfal language isafubjecr. of the higheft curiofity, the knowledge of which has always been thought utterly inacceffible. A part of which we fhall however here attempt. Light, found, and odours, are unknown to the foetus in the womb, which, except the few fenfations and motions already mentioned, fleeps away its time infenfible of the bufy world. But the moment it arrives into day, it begins to experience rmny vivid pains and pleafures ; thefe are at the fame time at- tended with certain mufcuiar motions, and from this their early, Sect. XVI. 8. I. OF INSTINCT. 1 1 1 early, and individual aflbciation, they acquire habits of occur- ring together, that are afterwards indiflbluble. 1. Of Fear, As foon as the young animal is born, the firft important fen- fations, that occur to him, are occafioned by the oppreflion about his precordia for want of refpiration, and by his fudden tranfi- tion from ninety-eight degrees of heat into fo cold a climate.— He trembles, that is, he exerts alternately all the mufcles of his body, to enfranchife himfeif from the oppreflion about his bofom, and begins to breathe with frequent and fhort refpirations \ at the fame time the cold contracts his red Ikin, gradually turning- it pale ; the contents of the bladder and of the bowels are evac- uated : and from the experience of thefe firft difagreeable fenfa- tions the paflion of fear is excited, which is no other than the expectation of difagreeable fenfations. This early aflbciation of motions and fenfations perfifts throughout life ; the paflion of fear produces a cold and pale (kin, with tremblings, quick refpi- ration, and an evacuation of the bladder and bowels, and thus conftitutes the natural or univerfal language of this paflion. On obferving a Canary bird this morning, January 28, 1772, at the houfe of Mr. Harvey, near Tutbury, in Derbyfhire, I was told it always fainted away, when its cage was cleaned, and de- fired to fee the experiment. The cage being taken from the ceiling, and its bottom drawn out, the bird began to tremble, and turned quite white about the root of his bill : he then open- ed his mouth as if for breath, and refpired quick, flood ftraighter up on his perch, hung his wings, fpread his tail, clofed his eyes, and appeared quite iliff and cataleptic for near half an hour, and at length with much trembling and deep refpirations came gradually to himfeif. 2. Of Grief That the internal membrane of the noftrils may be kept al- ways moid, for the better perception of odours, there are two canals, that conduct the tears after they have done their office in moiftening and cleaning the ball of the eye into a fack, which is called the lacrymal fack 5 and from which there is a duct, that opens into the noftrils : the aperture of this duct is formed of exquifite fenfibility, and when it is ftimulated by odorous particles, or by the drynefs or coldnefs of the air, the fack con- tracts itfelf, and pours more of its contained moifture on the or- gan of fmell, By this contrivance the organ is rendered more fit Mb OF INSTINCT. Sect. XVI. 8. aj fit for perceiving fuch odours, and is preferred from beino- in- jured by thofe that are more ftrong or corrofive. Many other receptacles of peculiar fluids difgorge their contents, when the ends of their duels are ftimulated ; as the gall bladder, when the contents of the duodenum ftimulale the extremity of the com- mon bile duel: : and the falivary glands, when the termination of their duels in the mouth are excited by the ftimulus of the food we mailicate. Atque veficulx feminales iuum exprim'unt fiuidum glande penis fricata. The coldnefs and drynefs of the atmofphere, compared with the warmth and moifture, which the new-born infant had juft before experienced, difagreeably affecl: the aperture of this lacry- mal fack : the tears, that are contained in this fack, are poured into the noftrils, and a further fupply is fecreted by the lacry- mal glands, and diffufed upon the eye-bails ; as is very vifible in the eyes and noftrils of children foon after their nativity. The fame happens to us at our maturer age, for in fevere fro weather, fnivelling and tears are produced by the coldnefs and drynefs of the air. But the lacrymal glands, which feparate the tears from the' blood, are fituated on the upper external part of the globes of each eye ; and, when a greater quantity of tears are v i, we contract the forehead, and bring down the eye-brows, and ufe many other diftortions of the face, to comprefs thefe glands. Now as the fuffocating fenfation, that produces refpiration, is removed almoft as foon as perceived, and does not recur again : this difagreeable irritation of the lacrymal duels, as it muft fre- quently recur, till the tender organ becomes ufed to variety of odours, is one of the firfl pains that is repeatedly attended to : and hence throughout our infancy, and in many people through- out their lives, all difagreeable fenfations are attended with fniv- elling at the nofe, a profufion of tears, and fome peculiar diftor- tions of countenance : according to the laws of early affociation before mentioned, which conilitur.es the natural or univerfal language of grief. You may affure yourfelf of the truth of this obfervation, if you will attend to what paftes, when you read a diftrefsful tale alone ; before the tears overflow your eyes, you will invariably feel a titiilation at that extremity of the lacrymal duel:, which terminates in the noftril, then the compreftion of the eyes fuc- ceeds, and the profufion of tears. Linnaeus aflerts, that the female bear (beds tears in grief; tl fame has been fai *794- On the northern coaft of Ireland a friend of mine &w above i20 OF INSTINCT. Sect. XVI. u. i. a hundred crows at once preying upon mufcles ; each crow took a mufcle Up into the air twenty or forty yards high, and let it fall on the (tones, and thus by breaking the fheil, got pof- ieflion of the animal. — A certain philofopher (I think it was Anaxagoras) walking along the fea-fhore to gather fhelis, one 6f thefe unlucky birds miftaking his bald head for a ftone, drop- ped a ihejl fifh upon it, and killed at once a philofopher and an cylivr. The Martin, hirundo urbica, is faid by Linnaeus to dwell on the outfide of houfes in Europe under the eaves, and to return with the early foliage. And that, when it has built, the fpar- row, fringilla domdtica, frequently occupies the finifhed nelt ; but that the martin convoking its companions, while fome guard the captive enemy, others bring clay, exactly clofe up the en- trarice, and fly away leaving the intruder to be fuffocated. Syft. Natttr. PafT. Hirundo. A fimilar relation was printed many years ago iti the Gentleman's Magazine. Our domeftic animals, that have fome liberty, are alfo pofTefT- ed of fome peculiar traditional knowledge : dogs and cats have been forced into each other's foeiety, though naturally animals of a very different kind, and have hence learned from each other to eat dog's grafs (agroftis canina) when they are lick, to promote vomiting. I have feen a cat miftake the blade of barley for this grafs, which evinces it is an acquired knowledge. They have alfo learnt of each other to cover their excrement and urine ; —about a fpoonful of water was fpilt upon my hearth from the tea-kettle, and I obferved a kitten cover it with alhes. Hence this mult alfo be an acquired art as the creature miftook the ap- plication of it. To preferve their fur clean, and efpecially their whifkers, cats warn their faces, and generally quite behind their ears, every time they eat. As they cannot lick thofe places with their tongues, they firft wet the infide of the leg with faliva, and then repeat- edly wafh their faces with it, which muft originally be an efledt of reafoning, becaufe a means is ufed to produce an effect 5 and feems afterwards to be taught or acquired by imitation, like the greateft part of human arts. Thefe animals feem to pofTefs femething like an additional fenfe by means of their whifkers ; which have perhaps fome analogy to the antenna? of moths and butterflies. The whifkers of cats confifl not only of the long hairs on their upper lips, but they have alfo four or five long hairs ftanding up from each eye- brow, and alfo two or three on each cheek ; all which when the animal eredts them, make with their points fo many parts •f the periphery of a circle, of an extent at leaft equal to the circumference Sect. XVI. 1 1 . I . OF INSTINCT. 1 % 1 circumference of any part of their own bodies. With this in- ftrument, I conceive, by a little experience, they can at once de- termine, whether any aperture amongft hedges or fhrubs, in which animals of this genus live in their wild ftate, is large enough to admit their bodies ; which to them is a matter of the greateft confequence, whether purfuing or purfued. They have likewife a power of erecting and bringing forward the whif- kers on their lips ; which probably is for the purpofe of feeling, whether a dark hole be further permeable. The antennae, or horns of butterflies and moths, who have awkward wings, the minute feathers of which are very liable to injury, ferve, I fuppofe, a fimilar purpofe of meafuring, as they fly or creep amongft the leaves of plants and trees, whither their wings can pafs without touching them. I this morning faw a terrier bitch repeatedly lick her paws, and wafh her face on both fides, and over her eyes, exactly as cats do ; from whom I fuppofe me had acquired this art, as fhe liv- ed in the parlour with two of them. Mr. Leonard, a very intelligent friend of mine, faw a cat catch a trout by darting upon it in a deep clear water at the mill at Weaford, near Litchfield. The cat belonged to Mr. Stanley, who had often feen her catch fijfh in the fame manner in fummer, when the mill-pool was drawn fo low1 that the fi(h could be feen. I have heard of other cats taking filh in (hallow water, as they flood on the bank. This feems a natural art of taking their prey in cats, which their acquired delicacy by do- meftication has in general prevented them from ufing, though their defire of eating fifh continues in its original ftrength. Mr. White, in his ingenious Hiftory of Selbourne, was wit- nefs to a cat's fuckling a young hare, which followed her about the garden, and came jumping to her call of affection. At El- ford, near Litchfield, the Rev. Mr. Sawley had taken the young ones out of a hare, which was fhot ; they were alive, and the cat, who had juft loft her own kittens, carried them away, as it was fuppofed, to eat them ; but it prefently appeared, that it was affection not hunger which incited her, as (he fuckled them, and brought them up as their mother. Other inftances of the miftaken application of what has been termed inftinct may be obferved in flies in the night, who mis- taking a candle for day-light, approach and periih in the flame. So the putrid fmell of the ftapelia, or carrion-flower, allures the large flefh-fly to depofit its young worms on its beautiful petals, which periih there for want of nourifliment. This therefore cannot be a neceflary inftinct., becaufe the creature miftakes the application of it. Vol. I. R Though 122 OF INSTINCT. Sect. XVI. u. i. Though in this country horfes fhew little veftiges of policy, yet in the deferts of Tartary, and Siberia, when hunted by the Tartars they are feen to form a kind of community, fet watch- es to prevent their being furprifed, and have commanders, who dire£t, and haften their flight, Origin of Language, Vol. I. p. 212. In this country, where four or five horfes travel in a line, the firft always points his ears forward, and the laft points his backward, while the intermediate ones feem quite carelefs in this refpecl ; which feems a part of policy to prevent furprife. As all animals depend moft on the ear to apprize them of the ap- proach of danger, the eye taking in only half the horizon at ence, and horfes poflefs a great nicety of this fenfe ; as appears from their mode of fighting, mentioned No. 8. 5. of this Sec- tion, as well as by common obfervation. There are fome parts of a horfe, which he cannot conveni- ently rub, when they itch, as about the moulder, which lie can neither bite with his teeth, nor fcratch with his hind foot ; when this part itches, he goes to another horfe, and gently bites him in the part which he wifhes to be bitten, which is imme- diately done by his intelligent friend. I once obferved a youn^ foal thus bite its large mother, who did not choofe to drop the grafs flie had in her mouth, and rubbed her nofe againft the foal's neck inftead of biting it ; which evinces that lhe knew the defign of her progeny, and was not governed by a neceflary inftincl: to bite where (he was bitten. Many 0/ iur Ihrubs, which would otherwife afford an agree- able food to hcrfes, are armed with thorns or prickles, which fecure them from thofe animals ; as the holly, hawthorn, goofe- berry, gorfe. In the extenfive moorlands of Staffordfhire, the horfes have learnt to ftamp upon a gorfe-buffi with one of their forefeet for a minute together, and when the points are broken, they eat it without injury. The horfes in the new foreft in Hampfhire are affirmed to do the fame by Mr. Gilpin. Foreft Scenery, II. 25 1, and 1 12. Which is an art other horfes in the fertile parts of the country do not poffefs, and prick their mouths till they bleed, if they are induced by hunger or caprice to at- tempt eating gorfe. Swine have a fenfe of touch as well as of fmell at the end of their nofe, which they ufe as a hand, both to root up the foil, ^and to turn over and examine objects of food, fomewhat like the prcboicis of an elephant. As they require flicker from the cold in this climate, they have learnt to collect draw in their uths to make their neft, when the wind blows cold ; and to cali their companions by repeated cries to afiift in the work, and 1 to their warmth by their numerous bed-fellows. Hence thefe Sect. XVI. i i. i. OF INSTINCT. 1 23 thefe animals, which are efteemed fo unclean, have alio learned never to befoul their dens, where they have liberty, with their own excrement ; an art, which cows and horfes, which have open hovels to run into, have never acquired. I have obferved great fagacity in fwine ; but the fhort lives we allow them, and their general confinement, prevents their improvement, which might probably be other wife greater than that of dogs. Inftances of the fagacity and knowledge of animals are very numerous to every obferver, and their docility in learning vari- ous arts from mankind, evinces that they may learn fimilar arts from their own fpecies, and thus be poftefTed of much acquired and traditional knowledge. A dog whofe natural prey is fheep, is taught by mankind, not only to leave them unmolefted, but to guard them *, and to hunt, to let, or to deflroy other kinds of animals, as birds, or vermin 5 and in fome countries to catch fifh, in others to find truffles, and to practife a great variety of tricks ; is it more furprifmg that the crows fhould teach each other, that the hawk can catch lefs birds, by the fuperior fwiftnefs of his wing, and if two of them follow him, till he fucceeds in his defign, that they can by force (hare a part of the capture ? This I have formerly ob- ferved with attention and aftonifhment. There is one kind of pelican mentioned by Mr. Ofbeck, one of Linnseus's^ravelling pupils (the pelicanus aquilus), whofe food is fifh *, and which it takes from other birds, becaufe it is not formed to catch them itfelf ; hence it is called * the Eng- lifh a Man-of-war-bird, Voyage to China, p. 88. There are many other interefting anecdotes of the pelican and cormorant, collected from authors of the beft authority, in a well-managed Natural Hiftory for Children, publifhed by Mr. Galton. John- fon. London. And the following narration from the very accurate Monf. Adanfon,in his voyage to Senegal, may gain credit with the read- er : as his employment in this country was folely to make ob- fervations in natural hiftory. On the river Niger, in his road to the iflandGriel,he faw agreat numberof pelicans, or wide throats. u They moved with great ftate like fwans upon the water, and are the largeft bird next to the oftrich ; the bill of the one I kill- ed was upwards of a foot and half long, and the bag fattened underneath it held two and twenty pints of water. They fwim in flocks, and form a large circle, which they contract afterwards, driving the fifh before them with their legs : when they fee the fifh in fufficient number confined in this fpace, they plunge their bill wide open into the water, and Jhut it again with great quicknefs. i24 OF INSTINCT. Sect. XVI. 12. I quicknefs. They thus get fifh into their throat-bag, which they eat afterwards on fhore at their leifure." P. 247. Another curious effort of defign, or ufe of means in animals, is related by Abbe Grofier, in his Defcription of China, Vol. I. p. 562. A kind of tiger is feen in China, which has a body like a dog, but no tail, and is remarkably fwift and ferocious. If any one meets this animal, and to efcape from his fury climbs up a tree, the tiger immediately fends forth a loud yell, and feveral other tigers arrive ; which altogether dig up the earth round the roots of the tree, and overturning it, feize their prey. The rattlefnake and black ferpent of America alfo mould here be mentioned, which are fuppofed to pofTefs an inftincl:ive pow- er of fafcinating birds ; as many birds have been feen repeatedly to run to them and to retreat from them with piteous fcreams, till the fnake has feized and devoured them. I formerly fuf- pected, that this ferpent had hid himfelf in the bullies, and had fecretly wounded the bird, and followed it with his fteady eye, till the poifon inftilled into the wound had time to take effect ; and that the bird then fell from the tree into his mouth. But from an ingenious paper, which Dr. B. S. Barton, ProfefTor of Natural Hiftory in Pennfylvania, has favoured me with, and ■which will be publifhed in their Philofophical Tran factions, it is clearly fhewn, that this piteous cry, and approach, and retreat, of the bird fuppofed to be fafcinated is fimply ap.v attack made by the female bird on the ferpent in defence of her young ; which credulity and the love of admiration has converted into a prodigy of fafcination, which is ftill credited by the multitude in America. This circumftance of the mother bird daring to defend her young from a ferpent, till fhe was devoured by him, and her fcreaming around him, is defcribed by that great ob- ferver of nature, the immortal Homer, above 2000 years ago. Iliad. Lib. 2. 1. 340. XII. The knowledge and language of thofe birds, that fre- quently change their climate with the feafons, is ftill more ex- tenfive : as they perform thefe migrations in large focieties, and are lefs fubjeft to the power of man, than the refident tribes of birds. They are faid to follow a leader during the day, who is occafionally changed, and to keep a continual cry during the night to keep themfeives together. It is probable that thefe emigrations were at firft undertaken as accident directed, by the more adventurous of their fpecies, and learned from one another like the difcoveries of mankind in navigation. The following circumftances ftrongly fupport this opinion. 1. Nature has provided thefe animals, in the climates where they are produced, with another refource, when the feafon be- come Scct. XVI. 12. 2. OF INSTINCT. 125 comes too cold for their conftitutions, or the food they were fup- ported with ceafes to be fupplied : I mean that of fleeping. Dormice, fnakes, and bats, have not the means of changing their country ; the two former from the want of wings, and the lat- ter from his being not able to bear the light of the day. Hence thefe animals are obliged to make ufe of this refource, and fleep during the winter. And thofe fwallows that have been hatched too late in the year to acquire their full ftrength of pinion, or that have been maimed by accident or difeafe, have been frequently- found in the hollows of rocks on the fea coafts, and even under water in this torpid ftate, from which they have been revived by the warmth of a fire. This torpid ftate of fwallows is tefti- fied by innumerable evidences both of ancient and modem names. Ariftotle fpeaking of the fwallows fays, « They pafs into warmer climates in winter, if fuch places are at no great diftance ; if they are, they bury themfelves in the climates where they dwell," (8. Hilt, c 16. See alfo Bernards Phyf. Theol. v. ii. p. 177.) The hybernation of animals is mentioned by M. Fabricius, who fuppofes it only to happen to animals, which originally be- longed to a warmer climate, and adds, that when thefe animals are carried back to a warmer climate, and fupplied plentifully with food, they ceafe to hybernate. Hence their emigrations cannot depend on a necejfary inftinct, as the emigrations themfelves are not necejfary. 2. When the weather becomes cold, the fwallows in the neighbourhood afTemble in large flocks ; that is, the unexperi- enced attend thofe that have before experienced the journey they are about to undertake : they are then feen fome time to hover on the coaft, till there is calm weather, or a wind, that fuits the direction of their flight. Other birds of paffage have been drowned by thoufands in the fea, or have fettled on (hips quite exhausted with fatigue. And others, either by miftaking their courfe, or by diftrefs of weather, have arrived in countries where they were never feen before : and thus are evidently fubjecl: to the fame hazards that the human fpecies undergo, in the execu- tion of their artificial purpofes. 3. The fame birds are emigrant from fome countries and not fo from others : the fwallows were feen at Goree in January by an ingenious philofopher of my acquaintance, and he was told that they continued there all the year ; as the warmth of the cli- mate was at all feafons fufficient for their own conftitutions, and for the production of the flies that fupply them with nourifh- ment. Herodotus fays, that in Libya, about the fprings of the Nile, the fwallows continue all the year. (L. 2) Quails 1 26 OF INSTINCT. Sect. XVI. 12.3: Quails (tctrao coturnix, Lin.) are birds of pafiage from the coaft of Barbary to Italy, and have frequently fettled in large fhoals on (hips fatigued with their flight. (Ray, Wifdom of God, p. 1 29. Derham Phyfic. Theol. v. ii. p. 178.) Dr. Ruf- fel, in his hiftory of Aleppo, obferves that the fwallows vifit that country about the end of February, and having hatched their young difappear about the end of July ; and returning again about the beginning of October, continue about a fortnight, and then again difappear. (P. 70.) When my late friend Dr. Chambres of Derby was on the ifland of Caprea in the bay of Naples, he was informed that great flights of quails annually fettle on that ifland about the begin- ning of May, in their pafTage from Africa to Europe. And that they always come when the fouth-eaft wind blows, are fatigued when they reft on this ifland, and are taken in fuch amazing quantities and fold to the Continent, that the inhabitants pay the bifhop his ftipend out of the profits arifing from the fale of them. The flights of thefe birds acrofs the Mediterranean are record- ed near three thoufand years ago. " There went forth a wind from the Lord and brought quails from the fea, and let them fall upon the camp, a day's journey round about it, and they were two cubits above the earth," (Numbers, chap. ii. ver. 31.) In our country, Mr. Pennant informs us, that fome quails migrate, and others only remove from the internal parts of the ifland to the coafts, (Zoology, octavo, 210.) Some of the ring- doves and ftares breed here, others migrate, (ibid. 510, 511.) And the flender billed fmall birds do not all quit thefe kingdoms in the winter, though the difficulty of procuring the worms and infects, that they feed on, fupplies the fame reafon for migra- tion to them all, (ibid. 511.) Linnams has obferved, that in Sweden the female chaffinches quit that country in September, migrating into Holland, and leave their mates behind till their return in fpring. Hence he has called them Fringilla caslebs, (Amam. Acad. ii. 42. iv. 595-) Now in our climate both fexes of them arc perennial birds. And Mr. Pennant obferves that the hoopoe, chatterer, hawfinch, and crofs-bill, migrate into England fo rarely, and at fuch uncertain times, as not to deferve to be ranked among our birds of paf- fage, (Zool. 8vo. 511.) The water fowl, as geefe and ducks, are better adapted for long migrations, than the other tribes of birds, as, when the weather is calm, they can not only reft themfelves, or fleep upon the ocean, but poflibly procure fome kind of food from it. Hence in Siberia., as focn as the lakes are frozen, the water fowl, Sect, XVI. 12. 3. OF INSTINCT. 127 fowl, which are very numerous, all difappear, and are fuppofed to fly to warmer climates, except the rail, which, from its inabil- ity for long flights, probably fleeps, like our bat, in their winter. The following account from the Journey of Profeflbr Gmelin, may entertain the reader. " In the neighbourhood of Krafnoi- ark, amongft many other emigrant water fowls we obferved a great number of rails, which when purfued never took flight, but endeavoured to efcape by running. We inquired how thefe birds, that could not fly, could retire into other countries in the winter, and were told, both by the Tartars and AfTanians, that they well knew thofe birds could not alone pafs into other coun- tries: but when the cranes (les grues) retire in autumn, each one takes a rail (un rale) upon his back, and carries him to a warmer climate." Recapitulation, 1. All birds of paffage can exift in the climates, where they are produced. 2. They are fubje winch hiive been lefs frequently mixed with other trains or tribes of motion, X50 CATENATION Sect. XVII. 3. 2. motion, have the ftrongeft connexion. Thirdly, that of thefe, thofe, which were firft formed, have the ftrongeft: connexion. Fourthly, that if an animal motion be excited by more than one caufation, aflbciation, or catenation, at the fame time, it will be performed with greater Energy. 2. Hence alfo we underftand, why the catenations of irrita- tive motions are more ftrongly connected than thofe of the oth- er clafles, where the quantity of unmixed repetition has been equal ; becaufe they were firft formed. Such are thofe of the i fccerning and abforbent fyftems of veffels, where the action of the gland produces a fluid, which ftimulates the mouths of its correfpondent abforbents. The aflbciated motions feem to be the next moft ftrongly united, from their frequent repetition ; \ and where both thefe circumftances unite, as in the vital motions,! their catenations are indiflbluble but by the deftruction of the animal. 3. Where a new link has been introduced into a circle of actions by fome accidental defect: of ftimulus ; if that defect: of ftimulus be repeated at the fame part of the circle a fecond or a third time, the defective motions thus produced, both by the repeated defect of ftimulus and by their catenation with the parts of the circle of actions, will be performed with lefs and kfs energy. Thus if any perfon is expofed to cold at a certaiit hour to-day, fo long as to render fome part of the fyftem for a time torpid ; and is again expofed to it at the fame hour to-j morrow, and the next day ; he will be more and more arTectedl by it, till at length a cold fit of fever is completely formed, as] happens at the beginning of many of thofe fevers, which arcl called nervous or low fevers. Where the patient has flight pe-J riodical fhiverings and palenefs for many days before the febrile paroxyfm is completely formed. 4. On the contrary if the expofure to cold be for fo fhort a time, as not to induce any confiderable degree of torpor or qui-) efcence, and is repeated daily as above mentioned, it lofes itsf effect more and more at every repetition, till the conftitution can bear it without inconvenience, or indeed without beinrr con- fcious of it. As in walking into the cold air in frofty weather* The fame rule is applicable to increafed ftimulus, as of heat, or vinous fpirit, within certain limits, as is applied in the two laft paragraphs to Deficient Stimulus, as is further explained in Sc XXXVI. on the Periods of Difeafes. 5. Where irritation coincides with fenfation to produce the • catenations of motion, as in inflammatory fevers, they are t -xited with ftill greater energy than by the irritation alone. ... - tickled in play, bv a feather light- Sect. XVII. 3,6, OF MOTIONS. i5i ly pafled over the lips, or by gently vellicating the foles of their feet, laughter is mod vehemently excited ; though they can ftimulate thefe parts with their own fingers unmoved. Here the pleafurable idea of playfulnefs coincides with the vellication ;, and there is no voluntary exertion ufed to diminiih the fenfa- lion, as there would be, if a child ihould endeavour to tickle himfelf. See Sect, XXXIV. 1. 4. 6. And laftly the motions excited by the junction of volun- tary exertion with irritation are performed with more energy, than thofe by irritation fingly ; as when we liften to fmali noifes, as to the ticking of a watch in the night, we perceive the moft weak founds, that are at other times unheeded. So when we attend to the irritative ideas of found in our ears* which are generally not attended to, we can hear them ; and can fee the fpeefcra of objects, which remain in the eye, when- ever we pleafe to exert our voluntary power in aid of thofe weak actions of the retina, or of the auditory nerve. 7. The temporary catenations of ideas, which are caufed by the fenfations of pleafure or pain, are eafily difTevered either by irritations, as when a fudden noife difturbs a day-dream j or by the power of volition, as when we awake from fleep. Hence in our waking hours, whenever an idea occurs, which is incongru- ous to our former experience, we inftantly difTever the train of imagination by the power of volition, and compare the incon- gruous idea with our previous knowledge of nature, and reject it. This operation of the mind has not yet acquired a fpecific name, though it is exerted every .minute of our waking hours; unlefs it may be termed intuitive analogy. It is an act of reafoning of which we are unconfeious except from its effects in preferring the congruity of our ideas, and bears the fame re- lation to the fenforial power of volition, that irritative ideas, of which we are inconfeious except by their effects, do to the fenfo- rial power of irritation 5 as the former is produced by volition without our attention to it, and the latter by irritation without our attention to them. If on the other hand a train of imagination or cf voluntary ideas are excited with great energy, and paffing on with great vivacity, and become difTevered by fome violent ilimulus, as the difcharge of a piftol near one's ear, another circumftance takes place, which is termed surprise ; which by exciting violent irritation, and violent fenfation, employs for a time the whole fenforial energy, and thus dilfevers the paffing trains cf ideas, before the power of volition has time to compare them with the ufual phenomena of nature. In this cafe fear is generally companion of furprife, and adds tc - • ijarraflme.ntj as every %tz CATENATION, &c. Sect. XVII. 3. 7. one experiences in fome degree when he hears a noife in the dark, which he cannot inftantly account for. This catenation of fear with f urprife is owing to our perpetual experience of in- juries from external bodies in motion, unlefs we are upon our guard againft them. See Seel. XVIH. 17. XIX. 2. Many other examples of the catenations of animal motions are explained in Seel. XXXVI. on the Periods of Difeafes. SECT. Sect. XVIII. r, OF SLEEP. 153 SECT. XVIIL OF SLEEP. I. Volition is fufpe tided in Jleep. 2. fknfation continues. Dreams prevent delirium and inflammation* 3. Nightmare. 4. Ceafe^ lefs flow of ideas in dreams. 5. We feem to receive them by the fenfes. Optic nerve perfectly fenfible in fleep. Eyes lefs dazzled after dreaming of vifibk objecls. 6. Reverie, belief. 7, Hou) we di/linguiflj ideas from perceptions. 8. Variety of fcenery in. dreams y excellence of the fenfe of vi/ion. 9. Novelty of combina- tion in dreams. 1 o. Diftinclnsfs of imagery in dreams. 1 1 . Ra- pidity of tranfaclion in dreams. 12. Of meafuring time. Of dramatic time and place. Why a dull play induces fieepy and an inter efing one reverie. 13. Conjcioufnefs of our exifilence and identity in dreams. 14. How we awake fometimes fuddenly% fometimes frequently. I^. Irritative motions continue in fieepy internal irritations are fucceeded byfenfation. Senfibility increafes during jleepy and irritability. Morning dreams. Why epilepftes occur in Jeep. Mcflafy of children. Cafe of convulfions in Jleep*. Cramp, why painful. Ajlhma* Morning fweats* Increafe of heat. Increafe of urine in Jeep. Why more liable to take cold in. Jleep. Catarrh from thin night-caps. Why we feel chilly at the approach of Jeep, and at waking in the open air. 16. W^hy the gout commetices in Jeep. Secretions are more copious in Jleep, young animals and plants grow more in Jeep. 17. Inconfjlency of dreams. Ab fence of furprife in dreams, 18. Why we forget fine dreams and not others. 19. Sleep talkers awake with fur- prife. 20. Remote caufes of fleep. Atmofphere with lefs oxygens Compreffion of the brain in the Jpina bifida. By whirling on a horizontal wheel. By cold. 2 1 . Definition of Jleep. 1. There are four fituations of our fyflern, which in their moderate degrees are not ufually termed difeafes, and yet abound with many very curious and inftruclive phenomena ; thefe are fleep, reverie, vertigo, drunkennefs. Thefe we fhall previoufly confider, before we fi:ep forwards to develop the caufes and cUres of difeafes with the modes of the operation of medi- cines. As all thofe trains and tribes of animal motion, whieh are fubjected to volition, were the lalt that were caufed, their con- nexion is weaker than that of the other claiTes j arTd there is a peculiar circumftance attending this caufation, which is, tha<: it is entirely fufpended during fleep : whilfl tire other clafTes of Vol. I. W potion, i£4 OF SLEEP. Sect. XVIII. motion, which are more immediately neceflary to life, as thofe caufed by internal ftimuli, for inftance the pulfations of the heart and arteries, or thofe catenated with pleafuraole fenfa- tion, as the powers of digeftion, continue to ftrengthen their habits without interruption. Thus though man in his fleeping fiate is a much lefs perfect animal, than in his waking hours ^ and though he confumes more than one third of his life in this his irrational fituation ; yet is the wifdom of the Author of na-i ture manifeff. even in this feeming imperfection of his work. The truth of this aflertion with refpect to the large mufcles of the body, which are concerned in locomotion, is evident ; as no one in perfect fanity walks about in his fleep, or performs any domeftic oilices : and in refpecr. to the mind, we never ex- ercife our reafon or recollection in dreams ; we may fometimes J feem diffracted between contending paflions, but we never • compare their objects, or deliberate about the acquifition of thofej objects, if our ileep is perfect. And though many fynchronousl tribes or fucceflive trains of ideas may reprefent the houfes or walks, which have real exiflence, yet are they here introduced by their connexion with our fenfations, and are in truth ideasi of imagination, not of recollection. 2. For our fenfations of pleafure and pain are experienced with great vivacity in our dreams ; and hence all that motley group of ideas, which are caufed by them, called the ideas of imagination, with their various aflbciated trains, are in a very vivid manner acted over in the fenforium ; and thefe fometimesj call into action the larger mufcles, which have been much aflb-f ciated with them •, as appears from the muttering fentences,? which fome people utter in their dreams, and from the obfeure barking of fleeping dogs, and the motions of their feet and noflrils^ This perpetual flow of the trains of ideas, which conftitute our dreams, and which are caufed by painful or pleafurable fenfa- tion, might at firft view be conceived to be an ufelefs expen- diture of fenforial power. But it has been {hewn, that thofe motions, which are perpetually excited, as thofe of the arterial fyftem by the ftimalus of the blood, are attended by a great ac- cumulation of fenforial power, after they have been for a time fufpended *, as the hot-fit of fever is the confequence of the cold one. Now as thefe trains of ideas caufed by fenfation are perpetually excited during our waking hours, if they were to be fufpended in fleep like the voluntary motions, (which are exerted only by intervals during our waking hours,) an accumulation of fenforial power would follow ; and on our awaking a delirium would fupervene, fince thefe ideas caufed by fenfation would be produced with fuch energy, that we flioukl miitake the trains of Sect. XVIII. 3. OF SLEEP. ■ iS$ of imagination for ideas excited by irritation ; as perpetually happens to people debilitated by fevers on their firft awaking : for in thefe fevers with debility the general quantity of irrita- tion being diminifhed, that of fenfation is increafed. In like manner if the actions of the ftomach, interlines, and various glands, which are perhaps in part at leaft caufed by or catenated with agreeable fenfation, and which perpetually exift during our waking hours, were like the voluntary motions fufpended in our fleep ; the great accumulation of fenforial power, which would neceflarily follow, would be liable to excite inflammation in them. 3. When by our continued pofture in fleep fome uneafy fenfations are produced, we either gradually awake by the exer- tion of volition, or the mufcles connected by habit with fiich fenfations alter the position of the body ; but where the fleep is uncommonly profound, and thofe uneafy fenfations great, the difeafe called the incubus, or nightmare, is produced. Here the defire of moving the body is painfully exerted, but the power of moving it, or volition, is incapable of action, till we awake. Many lefs difagreeable ftruggles in our dreams, as when we wifh in vain to fly from terrifying objects, conftitute a {lighter degree of this difeafe. In awaking from the nightmare I have more than once obferved, that there was no diforder in my pulfe ; nor do I believe the -refpiration is laborious, as fome have affirm- ed. It occurs to people whofe fleep is too profound, and fome difagreeable fenfation exifts, which at other times would have awakened them, and have thence prevented the difeafe of night- mare ; as after great fatigue or hunger with too large afupper and wine, which occafion our fleep to be uncommonly profound. See No. 14, of this Section. 4. As the larger mufcles of the body are much more fre- quently excited by volition than by fenfation, they are but fel- dom brought into action in our fleep : but the ideas of the mind are by habit much more frequently connected with fenfation than with volition ; and hence the ceafelefs-flow of our ideas in dreams. Every one's experience will teach him this truth, for we all daily exert much voluntary mufcular motion : but few of mankind can bear the fatigue of much voluntary thinking. 5. A very curious circumftance attending thefe our fleeping imaginations is, that we feem to receive them by the fenfes. The mufcles, which are fubfervient to the external organs of fenfe, are connected with volition, and ceafe *to act in fleep -, hence the eyelids areclofed,andthe tympanumof the ear relaxed ; and it is probable a fimilarity of voluntary exertion may be necef- fary for the perceptions of the other nerves of ivufe ; for it is obferved i5* OF SLEEP. Sect. XVIII. $) obferved that the papillae of the tongue can be feen to- become erected, when we attempt to tafte any thing extremely grateful. Hewfon Ex^er. Enquir. V. ii. 186. Albini Annot. Acad. L. i. c. 15. Add to this, that the immediate organs of fenfe have no objects to excite them in the darkncfs and iilence of the night ; but their nerves ©f fenfe neverthelefs continue to poflefs their perfect activity fubfervient to all their numerous fenfitive con- nexions. This vrvacity of our nerves of fenfe during the time of fleep is evinced by a circumftance, which aimed every one muft at fome time or other have experienced ; that is, if we fleep in the daylight, and endeavour to fee fome object in our dream, the light is exceedingly painful to our eyes \ and after repeated ftruggles we lament in our fleep, that we cannot fee it. In this cafe I apprehend the eyelid is in fome degree opened by the vehemence of our fenfations ; and, the iris being dilated, the optic nerve fhews as great or greater fenfibility than in our waking hours-. See No. 15. of this Section. When we are forcibly waked at midnight from profound fleep, our eyes are much dazzled with the light of the candle for a minute or two, after there has been fufficient time allowed for the contraction of the iris ; which is owing to the accumulation 01 fenforial power in the organ of vifion during its ftate of lefs activity; But when we have dreamt much of vifible objects, this accumulation of fenforial power in the organ of vifion is leflened or prevented, and we awake in the morning without be- ing dazzled with the light, after the iris has had time to con- tract itfelf. This is a matter of great curiofity, and may be thus tried by any one in the day-light. Clofe your eyes, and cover them with your hat ; think for a minute on a tune, which you are accuftomed to, and endeavour to fing it with as little activity of mind as poflible. Suddenly uncover and open your eyes, and in one fecond of time the iris will contract itfelf, but you will perceive the day more luminous for fcvcral feconds, owing to the accumulation of fenforial power in the optic nerve. Then again clofe and cover your eyes, and think intenfely on a cube of ivory two inches diameter, attending firft to the north and fouth fides of it, and then to the other four fides of it ; then get a clear image in your mind's eye of all the fides of the fame cube coloured red ; and then of it coloured green ; and then of it coloured blue ; laitly, open your eyes as in the former exper- iment, and after the firft fecond of time allowed for the con- traction of the iris, you will not perceive any increafe of the lit of die day, or dazzling-, becaufe now there is no accumu- j Utiori of fenforial power in the optic nerve •, that having been expended by its aelion in thinking over viable objects. This Sect. XVIII. 6. OF SLEEP. ,s7 This experiment is not eaty to be made at firft, but by a few patient trials the fact appears very certain ; and fhews clearly, that our ideas of imagination are repetitions of the motions of the nerve, which were originally occafioned by the flimulus of external bodies ; becaufe they equally expend the fenforial power in the organ of fenfe. See Seel:. III. 4. which is analogous to pur being as much fatigued by thinking as by labour. 6. Nor is it in our dreams alone, but even in our waking rev- eries, and in great efforts of invention, fo great is the vivacity of our ideas, that we do not for a time diftinguifh them from the real prefence of fubftantial objects : though the external organs of fenfe are open, and furrounded with their ufual ftimuli. Thus whiHt I am thinking over the beautiful valley, through which I yefterday travelled, I do not perceive the furniture of my room : and there are fome, whofe waking imaginations are fo apt to run into perfect reverie, that in their common attention to a favour- ite idea they do*not hear the voice of the companion, who ac- cofts them, unlefs it is repeated with unuiual energy. This perpetual miftake in dreams and reveries, where our ideas of imagination are attended with a belief of the prefence of external objects, evinces beyond a doubt, that all our ideas are repetitions of the motions of the nerves of fenfe, by which they were acquired 5 and that this belief is not, as fome late phi- lofophers contend, an inftinct necelTarily connected only with our perceptions. 7. A curious queftion demands our attention in this place ; as we do not diftinguifh in our dreams and reveries between our perceptions of external objects, and our ideas of them in their abfencc, how do we diftinguifh them at any time ? In a dream, if the fweetnefs of fugar occurs to my imagination, the white- nefs and hardnefs of it, which were ideas ufually connected with the fweetnefs, immediately follow in the train ; and I believe a material lump of fugar prefent before my fenfes : but in my waking hours, if the fweetnefs occurs to my imagination, the ftimulus of the table to my hand, or of the "window to my eye, prevents the other ideas of the hardnefs and whitenefs of the fu- gar from fucceeding ; and hence I perceive the fallacy, and dis- believe the exiftence of objects correfpondent to thofe ideas, whofe tribes or trains are broken by the ftimulus of other ob- jects. And^jiurther in cur waking hours, we frequently exert our volition in comparing prefent appearances with fuch, as we have ufually obferved ; and thus correct the errors of one ien^ by our general knowledge of nature by intuitive analogy. See oect. XVII. 3.7. Whereas in dreams the power of volition is fufpended, we can recollect and compare our prefcnt ideas with none i5S OF SLEEP. Sect. XVIII. 8. none of our acquired knowledge, and are hence incapable of ob- . ierving any abfurclities in them. By this criterion we diitinguifh our waking from our fleeping hours, we can voluntarily recollect our fleeping ideas, when we are awake, and compare them with our waking ones ; but wc cannot in our fleep voluntarily recollect our waking ideas at all. 8. The vail variety of fcenery, novelty of combination, and diftinctnefs of imagery, are other curious circumftances of our jj ileeping imaginations. The variety of fcenery feems to arife from the fuperior activity and excellence of our fenfe of vifion •> < which in an inftant unfolds to the mind extenfive fields of pleaf- •erable ideas j while the other fenfes collect their objects flowly, and with little combination ; add to this, that the ideas, which this organ prefents us with, are more frequently connected with our feniation than thofe of any other. 9. The great novelty of combination is owing to another cir- cumitance j the trains of ideas, which are carried on in our waking thoughts, are in our dreams diflevered in a thoufand places by the fufpenfion of volition, and the abfence of irritative ideas, and are hence perpetually falling into new catenations. As explained in Seel:. XVI. 1. 9. For the power of volition is perpetually exerted during our waking hours in comparing our palling trains of ideas with our acquired knowledge of nature, snd thus forms many intermediate links in their catenation. And the irritative ideas excited by the flimulus of the objects, with which we are furrounded, are every moment intruded up- j en us, and form other links of our unceafing catenations of ideas. 10. The abfence of the ftimuliof external bodies, and of vo- lition, in our dreams renders the organs of fenfe liable to be more iirongly affected by the powers of fenfation, and of afib-i' ciation. For our defires or averfions, or the obtrufions of fur- Tounding bodies, diffever the fenfitive and affociate tribes of ideas in our waking hours by introducing thofe of irritation and volition amonglt them. Hence proceeds the fuperior diftinct- nefs of pleafurable or painful imagery in our ileep ; for we recat the figure and the features of a long loft friend, whom we loved, in our dreams with much more accuracy and vivacity than in our waking thoughts. This circum (lance contributes to prove, that our ideas of imagination are reiterations of thofe motions of our organs of fenfe, which were excited by external objects*, becaufe while we are expofed to the ftimuli of prefent objects, eur ideas of abfent objects cannot be fo dillinctly formed. 11. The rapidity of the fucceflion of tranfactions in our breams is almoft inconceivable •, infomuch that, when we are accidentally awakened by the jarring of a door, which is opened into Sect. XVIII. 12. OF SLEEP. i59 into our bedchamber, we fometimes ftream a whole hiftory of thieves or fire in the very in ft ant of awaking. During the fufpenfion of volition we cannot compare our other ideas with thofe of the parts of lime in which they exift ; that is, we cannot compare the imaginary fcene, which 45 before us, with thofe changes of it, which precede or follow it : becaufe this a induces reverie, as explained in the next Section. But when our fleep is imperfect, as when we have determin- ed to rife in half an hour, time appears longer to us than in moil other fituations. Here our folicitude not to overfleep the determined time induces us in this imperfect fleep to compare the quick changes of imagined fcenery with the parts of time or place, they would have taken up, had they real exiftence ; and that more frequently than in our waking hours ; and hence the time appears longer to us : and I make no doubt, but the per- mitted time appears long to a man going to the gallows, as the fear of its quick Japfe will make him think frequently about it. 13. As we gain our knowledge of time by comparing the preient fcenery with the pail and future, and of place by com- paring the fituations of objects with each other ; fo we gain our idea of confcioufnefs by comparing ourfelves with the fcenery around us \ and of identity by comparing our prefent confciouf- nefs with our paft confcioufnefs: as we never think of time or place, but when we make the compari'fons above mentioned, fo! we never think of confcioufnefs, but when we compare our own exiftence with that of other objects \ nor of identity, but when we compare our prefent and our paft confcioufnefs. Hence the confcioufnefs of our own exiftence, and of our identity, is owing to a voluntary exertion of our minds : and on that account in our complete dreams we neither meafure time, are furprifed at the fudde^i changes of place, nor attend to our own exiftence, or identity ; becaufe our power of volition is fufpended. But all thefe circumftances are more or lefs obfervable in our incom- plete ones -, for then we attend a little to the lapfe of time, and the changes of place, and to our own exiftence ; and even to our identity of perfon 5 for a lady feldom dreams, that me is a foldier ; nor a man, that he is brought to bed. 14. As long as our fenfations only excite their fenfual mo- tions, or ideas, our fleep continues found ; but as foon as they excite defires or averfions, our fleep becomes imperfect j and when that defire or averfion is fo ftrong, as to produce vo'un; motions, we begin to awake j the larger mufcles of the body are brought Sect. XVIII. i^ OF SLEEP, if* brought into ac~lion to remove that irritation or fenfation, which a continued pofture h2S caufed ; we ftretch our Iknibs, and yawn, and our fleep is thus broken by the accumulation of voU untary power. Sometimes it happens, that the act of waking is fuddenly pro- duced, and this foon after the commencement of Deep ; which is occafioncd by fome fenfation fo difagreeabie, as iuitantane- oufly to excite the power of volition 5 and a temporary action 01 all the voluntary motions fuddenly fucceeds, and we ftart awake* This is fometimeS accompanied with loud noife in the ears, and with fome degree of fear ; and when it is in great excels, lb as to produce continued convulfive motions of thole mufcles^ which are generally fubfervient to volition, it becomes epilepfy : the fits of which in fome patients generally commence during fleep. This differs from the nightmare defcribed in No. 3. o£ this Section, becaufe in that the difagreeabie fenfation is not fo great as to excite the power of volition into action ; for as foon as that happens, the difeafe ceafes. Another circumftance, which fometimes awakes people foert after the commencement of their fleep, is where the voluntary- power is already fo great in quantity as almoft to prevent them from falling alleep, and then a little accumulation of it foon again awakens them ; this happens in cafes of infanity, or where the mind has been lately much agitated by fear or anger* There is another circumftance in which fleep is likewife of iiiort duration, which ariies from great debility, as after great over-fatigue, and in fome fevers, where the ftrength of the patient is greatly diminifhed : as in thefe cafes the pulfe inter- mits of flutters, and the refpiration is previouily affected, it feems to originate from the want of fome voluntary efforts to facilitate refpiration, as when we are awake, and is further treated of in Vol. II. Clafs I. 2. 1. 2. on the Difeafes of the Voluntary Power. Art. Somnus interruptus. 15. We come now to thofe motions which depend on irrita- tion. The motions of the arterial and glandular fyftems con- tinue in our fleep, proceeding flower indeed, but ftronger and more uniformly, than in our waking hours, when they are in- commoded by external flimuJi, or by the movements of volition ; the motions of the mufcles fubfervient to refpiration continue to be flimulated into action, and the other internal fenies of hun- ger, thivft, and kill, are not only occafionally excited in our fleep, but their irritative motions are fucceeded by their uiual folia- tions, and make a part of the farrago of our dreams. Thefe fenfations of the want of air, of hunger, thirft, and lu^t, in our dreams, contribute to prove, that the nerves of the external Vo l. I. A fei . 1 62 OF SLEEP. Sect. XVIII. i i j' fenfes are alfo alive and excitable in our fleep ; but as the ftimuli of external objects are either excluded from them by the dark- nefs and filence of the night, or their accefs to them is prevented by the fufpenfion of volition, thefe nerves of fenfe fall more readily into their connexions with fenfation and with afTociation ; becaufe much fenforial power, which during the day was ex- pended in moving the external organs of fenfe in confequence of irritation from external ftimuli, or in confequence of volition, becomes now in fome degree accumulated, and renders the in- ternal or immediate organs of fenfe more eafily excitable by the other fenforial powers. Thus in refpect to the eye, the irritation, from external ftimuli, and the power of volition during our waking hours, elevate the eyelids, adapt the aperture of the iris to the quantity of light, the focus of the cryftalline humour, and the angle of the optic axifes to the diflance of the object, all which perpetual activity during the day expends much fenforial power, which is faved during our fleep. Hence it appears, that not only thofe parts of the fyftem, which are always excited by internal ftimuli, as the ftomach, inteftinal canal, bile-ducts, and the various glands, but the or- gans of fenfe alfo may be more violently excited into action by the irritation from internal ftimuli, or by fenfation, during our fleep thiin in our waking hours; becaufe during the fufpenfion of volition, there is a greater quantity of the fpirit of animation to be expended by the other fenforial powers. On this account our irritability to internal ftimuli, and our fenfibility to pain or . pleafure, is not only greater in fleep, but increafes as our fleep is prolonged. Whence digeftion and fecretion are performed better in fleep, than in our waking hours, and our dreams in the morning have greater variety and vivacity, as our fenfibility inj creafes, than at night when we firft lie down. And hence epi- leptic fits, which are always occafioned by fome difagreeable fen- fation, fo frequently attack thofe, who are fubjecl to them, in their fleep ; becaufe at this time the fyftem is more excitable by painful fenfation in confequence of internal ftimuli ; and the power of volition is then fuddenly exerted to relieve this pain, as explained Seel:. XXXIV. i. 4. There is a difeafe, which frequently affects children in the cradle, which is termed ecftafy, and feems to confift in certain exertions to relieve painful fenfation, in which the voluntary power h not fo far excited as totally to awaken them, and yet is fumcient to remove the difagreeable fenfation, which excites in this cafe changing the pofture of the child frequently lieves it. I have at this time under my care an elegant young *mart about Sect. XVIII. 15. OF SLEEP. 163 about twenty-two years of age, who feldom Sleeps mere than an hour without experiencing a convulfion fit ; which ceafes in about half a minute without any fubfequent Stupor. Lar^e dofes of opium only prevented the paroxyfms, fo long as they prevented him from Sleeping by the intoxication, which they in- duced. Other medicines had no effect on him. He was gently awakened every half hour for one night, but without good ef- fect, as he foon Slept again, and the fit returned at about the fame periods of time, for the accumulated fenforial power, which occasioned the increafed fenfibility to pain, was not thus exhauft- ed. This cafe evinces, that the fenfibility of the fyftem to in- ternal excitation increafes, as our Sleep is prolonged ; till the pain thus occafioned produces voluntary exertion ; which, when it is in its ufual degree, only awakens us"; but when it is more violent, it occafions convulfions. The cramp in the calf of the leg is another kind of convul- fion, which generally commences in fleep, occafioned by the continual increafe of irritability from internal Stimuli, or of fen- fibility, during that State of our exiflence. The cramp is a vi- olent exertion to relieve pain, generally either of the Skin from cold, or of the bowels, as in fome diarrhoeas, or from the muf- cles having been previously overflretched, as in walking up or down lteep hills. But in thefe convulfions of the mufcles, which form the calf of the leg, the contraction is fo violent as to occa- iion another pain in confequence of theb own too violent con- traction, as foon as the original pain, which caufed the contrac- tion, is removed. And hence the cramp, or fpafm, of thefe mufcles is continued without intermilfion by this new pain, un- like the alternate convulfions and remiflions in epileptic fits. The reafon, that the contraction of thefe mufcles of the calf of the leg is more violent during their convulfion than that of oth- ers, depends on the weaknefs of their an tagoniit mufcles ; for after thefe have been contracted in their ufual action, as at every ftep in walking, they are again extended, hot, as mod other mufcles are, by their antagonists, but by ths.wcight of the whole body on the balls of the toes ; and that weight applied to great mechanical advantage on the heel, that is, on the other end of the bone of the foot, which thus acts as a lever. Another difeafe, the periods of which generally commence during our Sleep, is the aSthma. Whatever may be the remote caufe of paroxyfms of aSthma, the immediate caufe of the con- vulsive rcipiration, whether in the common aSthma, or in what is termed the convulfive aSthma, which are perhaps only differ- ent degrees of the fame difeafe, muSt be owing to violent volun- tary exertions to relieve pain, as in other convulfions j and me increafe x6* OF SLEEP. Sect. XVIII. 16. r increafe of irritability to internal ftimuli, or of fen fibility, during fleep muft occafion them to commence at this time. Debilitated people, who have been unfortunately accuftomed to great ingurgitation of fpirituous potation, frequently part with a great quantity of water during the night, but with not more than lifual in the day-time. This is owing to a beginning torpor c* the abforbent fyftem, and precedes anafarca, which Commences in the day, but is cured in the night by the increafe of the irritability of the abforbent fyftem during fleep, which thus imbibes from the cellular membrane the fluids, which had. been accumulated there during the day •, though it is poflible the horizontal poiition of the body may contribute fomething to is purpofe, and alfo the greater irritability of fome branches of the abforbCnt veflels, which open their mouths in the cells of the celltftar membranej than that of other branches. As foon as a perfon begins to fleep, the irritability and fenfi- biiity of il\G fyttem begin to increafe, owing to the fufpenlionof volition and the exclusion of external ftimuli. Hence the ac- tions of the veflels in obedience to internal ftimulation become ftronger and more energetic, though lefs frequent in refpe£l to number. And as many of the fecretions are increafed, fo the heat of the fyftem is gradually increafed, and the extremities of feeble people, which had been cold during the day, become warm. Till towards morning many people become fo warm, as to find it neceflary to throw off fome of their bed-clothes, as foon as they awake ; and In others fweats are fo liable to occur towards morning during their fleep. Thus thofe, who are not accuftomed to fleep in the open air, are very liable to take cold, if they happen to fall afleep on a garden bench, or in a carriage with the window open. For as the fyftem is warmer during fleep, as above explained, if a cur- rent of cold air a (Feels any part of the body, a torpor of that part is more effectually produced, as when a cold blaft of air through ■ key-hole or cafement falls upon a perfon in a warm room. In thofe cafes the a fleeted part poflTefles lefs irritability in refpec"t to,, heat, from its having previously been expofed to a greater ftim«-: ulus of heat, as in the warm room, or during deep j and hence, when the ftimulus of heat is diminifhed, a torpor is liable to en- iue ; that is, we take cold. Hence people who fleep in the open air, generally feel chilly both at the approach of fleep, and or: feheif av aking ; and hence many people are perpetually fub- £1 to catarrh, it they fleep in a lei's warm head-drefs, than that- hey wear in the day. >. wot only the fenforial powers of irritation and of fenfa* .•n, but that of afl ion alfo appear to act with greater vig~ our Sect. XVIII. 16. OF SLEEP. x6$ our during the fufpenfion of volition in fleep. It will be fhewn in another place, that the gout generally fir ft attacks the liver, anti tliat afterwards an inflammation of the ball of the great toe commences by aflbciation, and that of the liver ceafes. Now as this change or metaftafis of the activity of the fyftem generally commences in fleep, it follows, that thefe aflociations of motion exift with greater energy at that time *, that is, that the fenfcrial faculty of aflbciation, like thofe of irritation and of fenfation, be- comes in fome meafure accumulated during the fufpenfion of volition. Other afibciate tribes and trains of motions, as well as the ir- ritative and fenfitive ones, appear to be rncreafed in their activ- ity during the fufpenfion of volition in fleep. As thofe which contribute to circulate the blood, and to perform the various fecretions ; as well as the afibciate tribes and trains of ideas, which contribute to f urnifh the perpetual dreams of our dream- ing imaginations. In fleep the fecretions have generally been fuppofed to be di- miniflied, as the expectojated mucus in coughs, the fluids dif- charged in diarrhoeas, and in faiivation, except indeed the fecre- tion of fweat, which is often vifibly increafed. This error feems to have arifen from attention to the excretions rather than to the fecretions. For the fecretions, except that of fweat, are generally received into reiervoirs, as the urine into the bladder, and the mucus of the interlines and lungs into their refpecYive cavities *, but thefe refervoirs do not exclude thefe fluids imme- diately by t.heir ftimulus, but require at the fame time fome vol- untary efforts, and therefore permit them to remain during fleep. And as they thus continue longer. in thofe receptacles in our fleeping hours, a greater part is abforbed from them, and the remainder becomes thicker, and fometimes in lefs quantity, though at the time it was fecreted the fluid was in greater quan- tity than in our waking hours. Thus the urine is higher col- oured after long lleep •, which mews, that a greater quantity has been fecreted, and that more of the aqueous and faline part has been rerabforbed, and the earthy part left in the bladder ; hence thick urine in fevers fhews only a greater action of the veiTels which fecrete it in the kidneys, and of thofe which abforb it from the bladder. The fame happens to the mucus expectorated in coughs, which is thus thickened by abforption of its aqueous and faiine parts ; and the fame of the fasces of the interlines. From hence it appears, and from what has been faid in No. 15 of this Sec- tion concerning the increafe of irritability and of fenfiftility ring fleep, that the fecretions are in general rather inc: than 156 OF SLEEP. Sect. XVIII. 1 7. than diminifhed during thefe hours of our exiflence ; and it is probable that nutrition is almoft entirely performed in fleep ; and that young animals grow more at this time than in their waking hours, as young plants have long fince been obferved to grow more in the night, which is their time of fleep. 17. Two other remarkable circumdances of our dreaming ideas are their inconfiftency, and the total abfence of furprife. Thus we feem to be prefent at more extraordinary metamor- phofes uf animals or trees, than are to be met with in the fable9 of antiquity 5 and appear to be tranfported from place to place, which feas divide, as quickly as the changes of fceaery are per- formed in a play-houfe ; and yet are not fenfible of their in- coniidency, nor in the lead degree affected with furprife. "We mult confuler this circumftance more minutely. In our waking trains of ideas, thofe that are inconfident with the ufual order of nature, fo rarely have occurred to us, that their con- nexion is the flighted of all others : hence, when a confident train of ideas is exhaufted, we attend to the external ftimuli, that ufual ly furround us, rather than to any inconfiflent idea, which might otherwife prefent itfelf : and if an incontinent idea fl»ould intrude itfelf, we immediately compare it with the preceding one, and voluntarily reject the train it would intro- duce ; this appears further in the Section on Reverie, in which ft ate of the mind external ftimuli are not attended to, and yet the dreams of ideas are kept confident by the efforts of volition. But as our faculty of volition is fufpended, and all external ftim« \i!i are excluded in fleep, this {lighter connexion of ideas takes place ; aud the train is faid to be inconfiflent ; that is, diffimi- iar to the ufual order of nature. But, when any confident train of fenfitive or voluntary ideas is flowing along, if any external dimulus affects us fo vio- lently, as to intrude irritative ideas forcibly into the mind, it difunites the former train of ideas, and we are affected withfur- r.rifc. Thefe dimuli of unufual energy or novelty not only dil- unite our common trains of ideas, but the trains of mufcular mo- tions aifo, which have not been long edabliihed by habit, and diiturb thofe that have. Some people become motionlefs by great furprife, the fits of hiccup and of ague have been often re- moved by it, and it even affects the movements of the heart, and arteries \ but in our fleep, all external ftimuli are excluded, and in confequence no furprife can exid. See Section XVII. 3. 7. 18. We frequently awake with pleafure from a dream, which has delighted us, without being able to recollect the tranfic- tions of it j unlefs perhaps at a didance of time, fome analogous idea m-ty introduce afrem this forgotten train : and in our wa- king Sect. XVIII. 19. OF SLEEP. 167 king reveries we fometimes in a moment lefe the train of thought, but continue to feel the glow of pleafure, or the depredion of fpirits, it occafioned : whilft at other times we can retrace with eafe thefe hiflories of our reveries and dreams. The above explanation of furprife throws light upon this fub- je£t. When we are fuddenly awaked by any violent ftimulus, the furprife totally difunites the trains of our fleeping ideas from thofe of our waking ones 3 but if we gradually awake, this does not happen j and we readily unravel the preceding trains of imagination. 10. There are various degrees of furprife j the more intent we are upon the train of ideas, which we are employed about, the more violent mult be the ftimulus that interrupts them, and the greater is the degree of furprife. I have obferved dogs, who liave flept by the fire, and by. their obfcure barking. and ftrug- gling have appeared very intent on their prey, that fhewed great furprife for a few feconds after their awaking by looking eagerly around them ; which they did not do at other times of waking. And an intelligent friend of mine has remarked, that his lady, who frequently fpeaks much and articulately in her ileep, could never recollecT: her dreams in the morning, when this happened to her : but that when fhe did not fpeak in her fleep, (he could always recollecT: them. Hence, when our fenfations aft. fo flrongly in fleep as to in- fluence the larger mufcles, as in thofe, who talk or ftruggle in their dreams j or in thofe, who are affected with complete rev- erie (as defcribed in the next Section), great furprife is produ- ced, when they awake ; and thefe as well as thofe, who are completely drunk or delirious, totally forget afterwards their imaginations at thofe times. 20. As the immediate caufe of fleep confifts in the fufpen- fion of volition, it follows, that whatever diminifhes the general quantity of fenforial power, or derives it from the faculty of volition, will conilitute a remote caufe of fleep 3 fuch as fatigue from mufcular or mental exertion, which diminifhes the general quantity of fenforial power ; or an incfeafe of the fenhtive mo- tions, as by attending to foft mufic, which diverts the fenforial power from the faculty of volition ; or lallly, by increafe of the irritative motions, as by wine, or food, or warmth ; which v. - C only by their expenditure of fenforial power diminifh the quan- tity of volition ; but alfo by their producing pleafurable fenfa- tions (which occafion other mufcular or fenfual motions in con- fequence), doubly decreafe the voluntary power, and thus more forcibly produce fleep. See Se<&. XXXI V. 1.4. Another method of inducing fleep is delivered in a very ing€- 11 ;■ 1 58 OF SLEEP. Sect. XVIII. 20* nious work lately publifhed by Dr. Beddoes. Who after la- menting that opium frequently occafions reftleflhefs, thinks, " that in mod cafes it would be better to induce fleep by the abftrac*tion of ftimuU, than by exhaufting the excitability ;" and udd$, " upon this principle we could not have a better foporific than an atmofphere with a diminiflied proportion of oxygene air, and that common air might be admitted after the patient "Was alloep." (Obferv. on Calculus, &c. by Dr. Beddoes, Mur- ray.) If it mould be found to be true, that the excitability of the fyftcm depends on the quantity of oxygene abforbed by the ' lungs in refpiration according to the theory of Dr. Beddoes, and of M. Girtanner, this idea of fleeping in an atmofphere with lefs oxygene in its compofition might be of great fervice in epileptic cafes, and in cramp, and even in fits of the afthma, where their, periods commence from the increafe of irritability during fleep. Sleep is likewife faid to be induced by mechanic preflurc on the brain in the cafes of fpina bifida. Where there has been a defeat of one of the vertebrae of the back, a tumour is protru- ded in confequence ; and, whenever this tumour has been com- preifed by the hand, fleep is faid to be induced, becaufe the who of the brain both within the head and fpine becomes com- pleted by the retroceflion of the fluid within the tumour. But by what means a comprefhon of the brain induces fleep lias not been explained, but probably by diminiming the fecretion of fenforial power, and then the voluntary motions become fuf- pended previously to the irritative ones, as occurs in mod dying perfons. Another way of procuring fleep mechanically was related to me by Mr. Brindfey. the famous canal engineer, who was brought up to the bunnefs of a mill-wright ; he told me, that heT had more than once feen the experiment of a man extending himfelf acrofs the large Rone of a corn-mill, and that by gradu- ally letting the ftone whirl, the man fell afleep, before the (toned had gained its full velocity, and he fuppofed would have died without pain by the continuance or increafe of the motion. In this cafe the centrifugal motion of the head and feet muft accu- mulate the blood in both thofe extremities of the body, aad thus comprefs the brain. Laftly, we mould mention the application of cold ; which, when in a lefs degree, produces watchfulnefs by the pain it oc- cafions, and the tremulous convulfions of the fubcutaneous muf- cles ; but when it is applied in great degree, is faid to produce I fleep. To explain this erTecl: it has been laid, that as the veflcls of the fkin and extremities become iirll torpid by the want of the ftimulus of heat, and as thence lefs blood is circulated thr Sect. XVIII. 21. OF SLEEP. 169 through them, as appears from their palenefs, a greater quantity of blood poured upon the brain produces fleep by its compref- fion of that organ. But I fhould rather imagine, that the fenfo- riai pov/er becomes exhaufted by the convulfive actions in con- ■fcquence of the pain of cold, and of the voluntary exercife pre^ vioufly ufed to prevent it, and that the fleep is only the beginning to die, as the fufpenfion of voluntary power in lingering deaths precedes for many hours the extinction of the irritative motions. 21. The following are the chara&eriftic circumftances at- tending perfect fleep. 1. The power of volition is totally fufpended. 2. The trains of ideas caufed by fenfation proceed with great- er facility and vivacity ; but become inconfiftent with the ufual order of nature. The mufcular motions caufed by fenfation continue ; as thofe concerned in our evacuations during infan- cy, and afterwards in digeftion, and in priapifmus. 3. The irritative mufcular motions continue, as thofe con- cerned in the circulation, in fecretion, in refpiration. But the irritative fenfual motions, or ideas, are not excited ; as the im- mediate organs of fenfe are not ftimulated into action by exter- nal objecls, which are excluded by the external organs of fenfe ; which are not in fleep adapted to their reception by the power of volition, as in our waking hours. 4. The aflbciate motions continue ; but their fir ft link is not excited into atlion by volition, or by external ftimuli. In all refpects, except thofe above mentioned, the three laft fenforiaJ. powers are fomewhat increafed in energy during the fufpenfion of volition, owing to the confequent accumulation of the fbiris of animation. * W Vol. I* ,• *Y SEC I / i/° OF REVERIE. Sect. XIX. i.' SECT. xix. ; OF REVERIE. i. Various degrees of reverie. 2. Sleep-walkers. Cafe of a young ly. Great fur prife at awaking. And total for gctfulnefs of what pnffed in reverie. 3. No fufpenjion of volition in reverie. 4. Senfitive motions continue, and are conftflent. 5. Irritative motions continue, but are not fucceeded by fenfation. 6. Volition necefhry for the perception of feeble impreffions. 7. A fociated mo- tions continue. 8. Nerves offenfe are irritable infeep, but not in reverie, p. Somnambuli are not afleep; Contagion received but once. 10. Definition of reverie. 1. "When we are employed with great fenfation of pleafure, t with great efforts of volition, in the purfuit of fome intereft- " ing train of ideas, we ceafe to be confeious of our exiflence, are inattentive to time and place? and do not diftinguifh this train of fenfitive and voluntary ideas from the irritative ones ex- cited by the prefence of external objects, though our organs of fenfe are furrounded with their accuftomed ftimuli, till at length this interefting train of ideas becomes exhaufted, or the appulfes of external objects are applied with unufal violence, and we re- turn with furprife, or with regret, into the common track of life. This is termed reverie or ftudium. In fome conftitutions thefe reveries continue a confiderable i time, and are not to be removed without greater difficulty, but are experienced in a lefs degree by us all ; when we attend ear- neftly to the ideas excited by volition or fenfation, with their af- fociated connexions) but are at the fame time confeious at inter- vals of the itimuli of furrpunding bodies. Thus in being pref- ent at a play, or in reading a romance, fome perforrs are fo totally 1 abforbed as to forget their ufual time of fleep, and to neglect their meals ; while ethers are faid to have been fo involved in volun- tary ftudy as not to have heard the difcharge of artillery ; and there is a (lory of an Italian politician, who could think fo intenfe- Jy on other fubjecls, as to be infenfible to the torture of the rack. From hence it appears, that thefe catenations of ideas and mufcular motions, which form the trains of reverie, are compo- fed both cf voluntary and fenfitive afTbciations of them ; and that thefe ideas differ from thofe of delirium or of fleep, as they are kept conhTient by the power of volition ; and they differ al- \o from jthe trains of ideas belonging to infanity, as they are as frequently excited by fenfation as by volition. But laftly, that the Sect. XIX. 2. OF REVERIE, i7I the whole fenforial power is fo employed oji thefe trains of com- plete reverie, that like the violent efforts of volition, as in con- vulfions or infanity ; or like the great activity of the irritative motions in drunkennefs ; or of the fenfitive motions in deliri- um ; they preclude all fenfation confequent to external ftimulus. 2. Thofe perfons, who are faid to walk in their fieep, are af- fected with reverie to fo great a degree, that it becomes a for- midable difeafe ; the efTence of which confifts in the inaptitude of the mind to attend to external flimuli. Many hiftories of this difeafe have been published by medical writers 5 of which therfc is a very curious one in the Laufanne Transactions. I fhall here fubjoin an account of fuch a cafe, with its cure, for the better illuftration of this fubject. A very ingenious and elegant young lady, with light eyes and hair, about the age of feventeen, in other refpects well, was fud- denly feized foon after her ufual menflruation with this very wonderful malady. The difeafe began with vehement convul- sions of aimoft every mufcle of her body, with great but vain ef- forts to vomit, and the mofl violent hiccoughs, that can be conceived : thefe were fucceeded in about an hour with a fixed fpafm ; in which one hand was applied to her head, and the other to fupport it : in about half an hour thefe ceafed, and the reverie began fuddenly, and was at firft manifeft by the look of her eyes and countenance, which feemed to exprefs attention. Then fhe converfed aloud with imaginary perfons with her eyes open, and could not for about an hour be brought to attend to the ftim- ulus of external objects by any kind of violence, which it was proper to ufe : thefe fymptoms returned in this order every day for five or fix weeks. Thefe converfations were quite confident, and we could un- derftand, what {he fuppofed her imaginary companions to anfwer, by the continuation of her part of the difcourfe. Sometimes ihe was angry, at other times (hewed much wit and vivacity, but was mod frequently inclined to melancholy. In thefe reveries (he fometimes fung over fome mufic with accuracy, and repeated whole pages from theEnglifh poets. In repeating fome lines iVom Mr. Pope's works fhe had forgot one word, and began again, en- deavouring to recollect it ; when ihe came to the forgotten word, it was ihouted aloud in her ear, and this repeatedly, to no p»r- pofe j buT by many trials ihe at length regained it herfelf. Thefe paroxyfms were terminated with the appearance of ln- expreifible furprife, and great fear, from which fhe was lome minutes in recovering herfelf, calling on her lifter with great ag- itation, and very frequently underwent a repetition of convul- sions, apparently from the pain of. fear. See .Sect. XVII. 3. 7. After « 1 72 OF REVERIE. Sect. XIX. 3. After having thus returned for about an hour every day for f.wo or three weeks, the reveries feemed to become lefs com- plete, and fome of their circumflances varied j fo that (lie could walk about the room in them without running againft any of the furniture •, though thefe motions were at fir ft very unfteady and tottering. And afterwards fhe once drank a difli of tea, when the whole apparatus of the tea-table was fet before her; and exprerTed fome fufpicion, that a medicine was put into it, and once feemed to fmell of a tuberofe, which was in flower in her chamber, and deliberated aloud about breaking it from the Item, faying, " it would make her fifter fo charmingly angry." At another time in her melancholy moments fhe heard the found of a parting bell, " I wifh I was dead," (he cried, liftening to the hd\, and then taking off one of her fhoes, as fhe fat upon the bed, " I love the colour black," fays (lie, « a little wider, and a little longer, even this might make me a coffin !" — Yet it is evi- dent, ihe was not fenfible at this time, any more than formerly, of ieeing or hearing any perfon about her ; indeed when great light was thrown upon her by opening the fhutters of the win- dow, her trains of ideas feemed lefs melancholy ; and when I have forcibly held her hands, or covered her eyes, ihe appeared to grow impatient, and would fay, fhe could not tell what to do, for (he could neither fee nor move. In all thefe circumflances her pulfc continued unaffected as in health. And when the par- oxyfm was over, fhe could never recollect a fingle idea of what had parTed in it. This aftonifhing difeafe, after the ufe of many other medi- cines and applications in vain, was cured by very large dofes of opium given about an hour before the expected returns of the paroxyfms ; and after a few relapfes, at the intervals of three or four months, entirely difappeared. But fhe continued at times to have other fymptoms of epilepfy. 3. We (hall only here confider, what happened during the time of her reveries, as that is our prefent fubjecl: •, the fits of convullion belong to another part of this treatife. Seel:. XXXIV. 4** There feems to have been no fupenfionof volition during the fits of reverie, becaufe fhe endeavoured to regain the loft idea in repeating the lines of poetry, and deliberated about breaking the tuberofe, and fufpected the tea to have been medicated. The ideas and mufcular movements depending on fenfa- faiion were exerted with their ufual vivacity, and were kept ■ -m being ineonhftent bv the power of volition, as appeared from her whole converfation, and was explained in Sect. XVII. 3. 7. and XVIII. 16. Sect. XIX. 5: OF REVERIE. § 173 5. The ideas and motions dependent on irritation during the firft weeks of her difeafe, whilft the reverie was complete, were never fucceeded by the feniation of pleafure or pain ; as fh» neither law, heard, nor felt any of the furrounding objects. Nor was it certain that any irritative motions fucceeded the fam- ulus of external objects, till the reverie became lefs complete, and then me could walk about the room without running againft the furniture of it. Afterwards, when the reverie became ftill lefs complete from the ufe of opium, fome few irritations were at times fucceeded by her attention to them. As when (he fmelt at*a tuberofe, and drank a difh of tea, but this only when (he feemed voluntarily to attend to them. 6. In common life when we Men to diftant founds, or wifh \to diftinguifh objects in the night, we are obliged ftrongly to exert our volition to difpofe the organs of fenfe to perceive them, and to fupprefs the other trains of ideas, which might interrupt thefe feeble fenfations. Hence in the prefent hiftory the ftrong- e(l ilimuli were not perceived, except when the faculty of voli- tion was exerted on. the organ of fenfe 5 and then even coi nion ftimuli were fometimes perceived : for her mind was fo ilrenuouflv employed in purfuingirs own trains of voluntary or fenfitive ideas, that no common ftimuli could fo far excite her attention as to difunite them ; that is, the quantity of volition 1 of fenfation already exifting was greater than any, which could be produced in confequence of common degrees offtimulation. But the few ftimuli of the tuberofe, and of the tea, which flic did perceive, were fuch, as accidentally coincided with the trains of thought, which were palling in her mind ; and hence did not difunite thofe trains, and create furprife. And their being per- ceived at all was owing to the power of volition preceding or coinciding with that of irritation. This explication is countenanced by a fact mentioned con- cerning a fomnambulift in the Laufanne Tranfactions, who fometimes opened his eyes for a ihort time to examine, where he was, or where his ink-pot ftood, and then {hut them again, dipping his pen into the pot every now and then, and writing on, but never opening his eyes afterwards, although he wrote on from line to line regularly, and corrected (ome errors of the pen, or in fpelling : fo much eafier was it to him to refer to his • ideas of the portions of things, than to his perceptions of them, 7. The aflbciated motions perfiited in their ufual channel, as appeared by the combinations of her ideas, and the ufe of her mufcles, and the equality of her pulfe ; for the natural motic is of the arterial fyftem, though originally excited like other mo- tions by ftinxuius, feem in part to continue bv their ail or after the body is at reft. From all which arguments it is manifeft, that thefe apparent retrograde gyrations of objects are not caufed by the rolling of the eyeballs ; firft, becaufe no ap- parent retrogreffion of objects is obferved in other rollings of the eyes. Secondly, becaufe the apparent retrogreffion of ob- jects continues many feconds after the rolling of the eyeballs ceafes. Thirdly, becaufe the apparent retrogreffion of objects is fometimes one way, and fometimes another, yet the rolling of the eyeballs is the fame. Fourthly, becaufe the rolling of the eyeballs exifts before the apparent retrograde motions of objects is obferved ; that is, before the revolving perfon flops. And fifthly, becaufe the apparent retrograde gyration of objects is produced, when there is no roiling of the eyeballs at all. Doctor Wells imagines, that no fpeclra can be gained in the eye, if a perfon revolves with his eyelids clofed, and thinks thi> a fufficient argument againftthe opinion, that the apparent pro- greffion of the fpeclra of light or colours in the eye can caufe the apparent retrogreffion of objects in the vertigo above defcri- bed ; but it is certain, when any perfon revolves in a light room with his eyes clofed, that he neverthelefs perceives differences of light both in quantity and colour through his eyelids, as he turns round; and readily gains fpeclra of thofe differences. And thefe fpeclra are not very different except in vivacity from thofe, which he acquires, when he revolves with unclofed eyes, fince if he •then revolves very rapidly the colours and forms of furrounding objects are as it were mixed together in his eye ; as when the prifmatic colours are painted on a wheel, they appear white as they revolve. The truth of this is evinced by the ftaggering or vertigo of men perfectly blind, when they turn round; which is not attended with apparent circulation of objects, but is a ver- tiginous diforder of the fenfe of touch. Blind men balance them- felves by their fenfe of touch ; which, being lefs adapted for perceiving fmall deviations from their perpendicular, occafions them to carry themfelves more erect in walking. This method of balancing themfelves by the direction of their prefTure againft the floor, becomes disordered by the unufual mode of action in turning round, and they begin to lofe their perpendicularity, that is, they become vertiginous ; but without any apparent cir- cular motions of viable objects. It will appear from the following experiments, that the appar- ent progreffion of the occular fpeclra of light or colours is the caufe of the apparent retrogreffion of objects, after a perfon h revolved, till he is vertiginous. Firft, when a perfon turns round in a light room with h t m eye-. 182 OF VERTIGO. Sect. XX. 6. eyes open, but clofes them before he flops, he will feem to be carried forwards in the direction he was turning for a fhort time after he (lops. But if he opens his eyes again> the objects before him inftantly appear to move in a retrograde dire&ion, and he lofes the fenfation of being carried forwards. The fame occurs if a perfon revolves in a light room with his eyes clofed •, when he flops, he feems to be for a time carried forwards, if his eyes are ilill clofed \ but the inftant he opens them, the furrounding objects appear to move in retrograde gyration. From hence it may be concluded, that it is the fenfation or imagination of our continuing to go forwards in the direction in which we were turning, that caufes the apparent retrograde circulation of ob- jects. Secondly, though there is an audible vertigo, as is known by the battement, or undulations of found in the ears, which many vertiginous people experience ; and though there is alfo a tangi- ble vertigo, as when a blind perfon turns round, as mentioned above ; yet as this circumgyration of objects is an hallucination or deception of the fenfe of fight, we are to look for the caufe of our appearing to move forward, when we flop with our eyes clofed after gyration, to forae affe£lion of this fenfe. Now, thirdly, if the fpeclra formed in the eye during our rotation con- tinue to change, when we fland Mill, like the fpettra defcribed in See~l. III. 3. 6". fuch changes mull fugged to us the idea or fenfation of our flill continuing to turn round j as is the cafe, when we revolve in a light room, and clofe our eyes before we flop. And laflly, on opening our eyes in the fituation above defcribed, the objects we chance to view amid thefe changing fpe£tra in the eye, mufl feem to move in a contrary direction ; as the moon fometimes appears to move retrograde, when fwift-t gliding clouds are palling forwards fo much nearer the eye of the beholder. To make obfervations on faint occular fpeclra requires forae degree of habit, and compofure of mind, and even patience ; fome of thofe defcribed in feet. XL. were found difficult to fee, by many, who tried them ; now it happens, that the mind, during the confufioii of vertigo, when all the other irritative tribes of motion, as well as thofe of vifion, are in iom? degree difturbed, together with the fear of falling, is in a very unfit ftate for the contemplation of fuchwer. ; r nfations,as are cccaHoned by faint occular fpectra. Yet after frequently revolving, both with my, eyes clofed, and with thern open, and attending to the fpect: remaining in them, by ihaciing the light from my eyelids more^ or lefs with rny hdnd, I at length ecafed to have the idea of going forward, after I ito^ped with my eyes clcfed ; and faw changjr tra Sect. XX. 6. OF VERTIGO, 1B3 ipe&ra in my eyes, which feemed to move, as it were, over the field of vifion ; till at length, by repeated trials on funny days, I perfuaded myfelf, on opening my eyes, after revolving fome time, on a fhelf of gilded books in my library, that I could per- ceive the fpectra in my eyes move forwards over one or two of the books, like the vapours in the air of a fummer's day ; and could fo far undeceive myfelf, as to perceive the books to fland (till. After more trials I fometimes brought myfelf to believe5 that I fow changing fpectra of lights and fhades moving in my eyes, after turning round for fome time, but did not imagine either the fpectra or the objects to be in a ftate of gyration. "I fpeak, however, with diffidence of thefe facts, as I could not al- ways make the experiments fucceed, when there was not a ftrong Ught in my room, or when my eyes were not in the moll proper ftate for fuch obfervations. The ingenious and learned M. Sauvage has mentioned other theories tb account for the apparent circumgyration of objects in vertiginous people. As the retrograde motions of the particles of blood in the optic arteries, by fpafm, or by fear, as is feen in the tails of tadpoles, and membranes between the fingers of frogs* Another caufe he thinks may be from the librations to one fide, and to the other, of the crystalline lens in the eye, by means of involuntary actions of the mufcies, which conftitute the ciliary procefs. Both thefe theories lie under the fame objection as that of Dr. Wells^before mentioned ; namely, that the apparent motions of objects, after the obferver has revolved for fome time, mould appear to vibrate this way and that ; and not to circulate [uniformly in a direction contrary to that, in which the obferver had revolved. M. Sauvage has, laftiy, mentioned the theory of colours left 112 i the eye, which he has termed impreflions on the retina. He fays, " Experience teaches us, that impreflions made on the retina by U vifible object remain fome feconds after the object is removed ; as appears from the circle of fire which we fee, when a fire-ftick is whirled round in the dark j therefore when we are carried round our own axis in a circle, we undergo a temporary vertigo* when we flop ; becaufe the impreffions of the circumjacent ob- jects remain for a time afterwards on the retina." Nofologc (Method. Claf. VIII. 1. 1. We have before obferved, that the changes of thefe colours remaining in the eye, evinces them to be motions of the fine terminations of the retina, and not impref- fions on it ; as impreffions on a paffive fubftance mud either re- main, or ceafe intirely. Having reperufed the ingenious EfTay of Dr. Wells on Single Vifion, and his additional obfervations in the Gentleman's Mag- azinc i and byjkving- ing and rocking children. And why pain is relieved by it. 4. Why drunkards Jl agger andfiammer, and are liable to weep. 5. And become delirious y Jleepy andflupid. 6. Or make pale urine and vomit. 7. Objetls are feen double. %. Attention of the mind dimini/hes drunkennefs. 9. Dif ordered irritative motions of all thefenfes. 10. Difeafes from drunkennefs. xi. Definition of drunkennefs. 1 . In the ftate of nature when the fenfe of hunger is appeafed by the ftimulus of agreeable food, the bufinefs of the day h over, and the human favage is at peace with the world, he then exerts little attention to external objects, pleafing reveries of im- agination fucceed, and at length fleep is the refult : till the nour- iihment which he has procured, is carried over every part of the fyftem to repair the injuries of action, and he awakens with frelh vigour, and feels a renewal of his fenfe of hunger. The juices of fome bitter vegetables, as of the poppy and the laurocerafus, and the ardent fpirit produced in the fermentation of the fugar found in vegetable juices, are fo agreeable to the nerves of the ftomach, that, taken in a fmall quantity, they in- ftantly pacify the fenfe of hunger ; and the inattention to external ftimuli with the reveries of imagination, and fleep, fucceeds, in the fame manner as when the ftomach is filled with other lefs intoxicating food. This inattention to the irritative motions occafioned by ex- ternal ftimuli is a very important circumftance in the approach of fleep, and is produced in young children by rocking their cra- dles : during which all viable objects become indiftinct to them. An uniform foft repeated found, as the murmurs of a gentle cur- rent, or of bees, are faid to produce the fame effect, by prefenting indiftinct ideas of inconfequential founds, and by thus dealing our attention from other objects, whilft by their continued reiterations they become familiar themfelves, and sve ceafe gradually to at- tend to any thing, and fleep enfues. 2. After great fatigue or inanition, when the ftomach is vid- denly filled with flefh and vegetable food, the inattention to ex- ternal i9z OF DRUNKENNESS. Sect. XXI. 3. ternal ftimuli, and the reveries of imagination, become fo confpic- ous as to amount to a degree of intoxication. The fame is at any time produced by fuperadding a little wine or opium to our com- mon meals ; or by taking thefe feparately in confiderable quan- tity ; and this more efticaciouily after fatigue or inanition ; be- caufe a Left quantity of any Simulating material will excite an organ into energetic action, after it has lately been torpid from defect of ftimulus ; as objects appear more luminous, after we have been in the dark ; and becaufe the fufpenfion of volition, which is the immediate caufe of lleep, is fooner induced, after a continued voluntary exertion has in part exhaufted the fenforial power of volition ; in the fame manner as we cannot contract a fingle mufcle long together without intervals of inaction. 3. In the beginning of intoxication we are inclined to lleep, as mentioned above, but by the excitement of external circum- ftances, as of noife, light, bufinefs, or by the exertion of volition,- we prevent the approaches of it, and continue to take into our ftomach greater quantities of the inebriating materials. By thefe means the irritative movements of the ftomach are excited into greater action than is natural ; and in confequence all the irrita- tive tribes and trains of motion, which are catenated with them, become fufceptible of ftronger action from their accuftomed ftimuli ; becaufe thefe motions are excited both by their ufual irritation, and by their aflbciation with the increafed actions of the flomach and lacteals. Hence the fkin glows, and the heat of the body is increafed, by the more energetic action ofthe,, whole glandular fyftem j and pleafure is introduced in confe- quence of thefe increafed motions from internal ftimulus. Ac-*, cording to Law 5. Sect. IV. on Animal Caufation. From this great increafe of irritative motions from internal (timuius, and the increafed fenfation introduced into the fyftero in confequence ; and fecondly, from the increafed fcnfitive mo- tions in confequence of thi . additional quantity of fenfation, 10 much fenforial power is expended, that the voluntary power be- comes feebly exerted, and the irritation from the ftimulus of ex- ternal objects is lefs forcible ; the external parts 0: the eye are not therefore voluntarily adapted to the diftances of objects, whence the apparent motions of thole objects either are feen double, or become too indiilinct for the purpofe of balancii the body, and vertigo is induced. Hence we become acquainted with that very curious circum- fiance, why the drunken vertigo is attended with an increafe of pleafure; for the irritative ideas and motions occafioned by i: tenia! ftimulus, that were not attended to in our fober hours, are now ju(f ucreaied as to be fucceeded by pleafurabk fenfation, Sect. XXI. 4. OF DRUNKENNESS. 15*3 fenfation, in the fame manner as the more violent motions of our organs are fucceeded by painful fenfation. And hence a greater quantity of pleafurable fenfation is introduced into the conftitu- tion -, which is attended in fome people with an increafe of be- nevolence and good humour. If the apparent motions of objects is much increafed, as when we revolve on one foot, or are fwung on a rope, the ideas of thefe apparent motions are alfo attended to, and are fucceeded with pleafurable fenfation, till they become familiar to us by fre- quent ufe. Hence children are at nrft delighted with thefe lands of exercife, and with riding, and failing, and hence rock- ing young children inclines them to Deep. For though in the vertigo from intoxication the irritative ideas of the apparent mo- tions of objects are indiftincl: from their decreafe of energy : yet in the vertigo occafioned by rocking or fwinging the irritative ideas of the apparent motions of objects are increafed in energy, and hence they induce pleafure into the fyftem, but are equally indiftinc~t, and in confequence equally unfit to balance ourielves by. This addition of pleafure precludes de lire or averfion, and in confequence the voluntary power is feebly exerted, and on this account rocking young children inclines them to ileep. In what manner opium and wine act in relieving pain i3 -another article, that well deferves our attention. There are many pains that originate from defecl as- well as from excefs of stimulus ; of thefe are thofe of the fix appetites of hunger, .third, lull, the want of heat, of diftention, and of frefh air. Thus if our cutaneous capillaries ceafe to acl; from the diminifned ftimu- lus of heat, when we are expofed to cold weather, or our ftom- ach is uneafy for want of food > thefe are both pains from defect of ftimulus, and in confequence opium, which humiliates all the moving fyftem into increafed aclion, muft relieve them. But this is not the cafe in thofe pains, which arife from excefs of ilimuius, as in violent inflammations : in thefe the exhibition of opium is frequently injurious by increasing the action of the fyftem already too great, as in inflammation of the bowels mor- tification is often produced by the ilimuius fcf opium. Where, however, no fuch bad confequenees follow ;. the ftimulus of opi- um, by increafing all the motions of the fyftem, expends fo much of the fenforial power, that the actions of the whole fyftem foon become feebler, and in confequence thofe which produced the. pain and inflammation. 4. When intoxication proceeds a, little further, the quantity of pleafurable fenfation is fo far increafed, that all defire ceafesj tor there is no pain in the fyftem to excite it. Hence the vol- untary exertions are diminifned, daggering a 1 I hammering fuo Vol. I. Bb Cded : i94 OF DRUNKENNESS. Sect. XXI. £, ceed ; and the trains of ideas become more and more inconfift- ent from this defect of voluntary exertion, as explained in the fections on ileep and reverie, whilft thofe paflions which are un- fixed with volition are more vividly felt, and {hewn with lefs referve ; hence pining love, or fuperftitious fear, and the maud- ling tear dropped on the remembrance of the moll trifling diitrefs. 5. At length all thefe circumftances are increafed ; the quan- tity of pleafure introduced into the fyftem by the increafed irrita- tive mufcular motions of the whole fanguiferous, and glandular, and abforbent fyftems, becomes fo great, that the organs of fenfe are more forcibly excited into action by this internal pleafurable fenfation, than by the irritation from the ftimulus of external objects. Hence the drunkard ceafes to attend to external ftimu- li, and as volition is now alfo fufpended, the trains of his ideas become totally inconfiftent as in dreams, or delirium : and at length a ftupor fucceeds from the great exhauftion of fenforial power, which probably does not even admit of dreams, and in which, as in apoplexy, no motions continue but thofe from in- ternal (timuli, from fenfation, and from aflbciation. 6. In other people a paroxyfm of drunkennefs has another ter- mination ; the inebriate, as foon as he begins to be vertiginous, makes pale urine in great quantities and very frequently, and at , length becomes lick, vomits repeatedly, or purges, or has pro- fufe fweats, and a tempoiary fever enfues with a quick ftrong pulfe. This in fome hours is fucceeded by fleep ; but the un- fortunate bacchanalian does not perfectly recover himfelf till about the fame time of the fucceeding day, when his courfe of inebriation bcjan. As fhewn in Sect. XVII. 1. 7. on Catena-! tion. The temporary fever with ftrcng pulfe is owing to the; fame caufe as the glow on the ikin mentioned in the third para-j graph of this Section : the flow of urine and ficknefs arife from the whole fyftem of irritative motions being thrown into confu- fion by their aflbciations with each other ; as in fea-ficknefs, mentioned in Sect. XX. 4. on Vertigo ; and which is more fully explained in Section XXIX. on Diabetes. 7. In this vertigo from internal caufes we fee objects double, as two candles inltead of one, which is thus explained. Two iines drawn through the axes of our two eyes meet at the object we attend to : this angle of the optic axes increafes or diminifhes with the lefs or greater distances of objects. All objects before or behind the place where this angle is formed, appear double ; as any one may obferve by holding up a pen between his eyes and the candle ; when he looks attentively at a fpot on the pen, and carclefsly at the candle, it will appear double ; and the re- verfe Sect. XXI. 8. OF DRUNKENNESS. 165 verfe when he looks attentively at the candle and carelefsly at the pen ; fo that in this cafe the mufcles of the eye, like thofe of the limbs, ftagger and are difobedient to the expiring efforts of volition. Numerous objects are indeed fometimes feen by the inebriate, occafioned by the refractions ma4e by the tears, which ftand upon his eye-lids. 8. This vertigo alfo continues, when the inebriate lies in his bed, in the dark, or with his eyes clofed ; and this more power- fully than when he is erect, and in the light. For the irrita- tive ideas of the apparent motions of objects are now excited by irritation from internal flimulus, or by affociation with other irritative motions ; and the inebriate, like one in a dream, be- lieves the objects of thefe irritative motions to be prefent, and feels himfelf vertiginous. I have obferved in this fituation, fo long as my eyes and mind were intent upon a book, the nek— nefs and vertigo ceafed, and were renewed again the moment I difcontinued this attention ; as was explained in the preceding account of fea-ficknefs. Some drunken people have been known to become fober inftantly from fome accident, that has ftrongly excited their attention, as*he pain of a broken bone, or the news of their houfe being on fire. 9. Sometimes the vertigo from internal caufes, as from in- toxication, or at the beginning of fome fevers, becomes fo univer- fal, that the irritative motions which belong to other organs of fenfe are fucceeded by fenfation or attention, as well as thofe of the eye. The vertiginous noife in the ears has been explained in Section XX. on Vertigo. The tafte of the faliva, which in general is not attended to, becomes perceptible, and the patients complain of a bad tafte in their mouth. The common fmells of the furrounding air fometimes excite the attention of thefe patients, and bad fmells are complained of, which to other people are imperceptible. The irritative mo- tions that belong to the fenfe of prefTure, or of touch, are attend- ed to, and the patient conceives the bed to-librate, and is fear- ful of falling out of it. The irritative motions belonging to the fenfes of distention, and of heat, like thofe above mentioned, become attended to at this time : hence we feel the pulfation of our arteries all over us, and complain of heat, or of cold, in parts of the body where there is no accumulation or diminution of actual heat. All which are to be explained, as in the lad: para- graph, by the irritative ideas belonging to the various fenfes be- ing now excited by internal ftimuli, or by their aflbciations with other irritative motions. And that the inebriate, like one in a dream, believes the external objects, which ufually caufed thefe irritative ideas, to be now prefent. 10. The i96 OF DRUNKENNESS. Sect. XXI. to. io. The difeafes in confequence of frequent inebriety, or of daily taking much vinous fpirit without inebriety, confift in the paralyfis, which is liable to fucceed violent llimulation. Or- gans, whofe actions are aflbciated with others, are frequently more affected tkan the organ, which is ftimulated into too vio-;' lent action. See Seel:. XXIV. -2. 8. Hence in drunken people it generally happens, that the fecretory veiTels of the liver be- come firft paralytic, and a torpor with confequent gall-ftones or fcirrhus of this vifcus is induced with concomitant jaundice ;. otherwife it becomes inflamed in confequence of previous tor- por, and this inflammation is frequently transferred to a more fenfible part, which is aflbciated with it, and produces the gout, or tne rofy eruption of the face, or fome other leprous eruption on the head, or arms, or legs. Sometimes the ftomach is firft affected, and paralyfis of the lafteal fyftem is induced : whence a total abhorrence from flefh-food, and general emaciation. In others the lymphatic fyftem is afTe^ed with paralyfis, and drop- fy is the confequence. In fome inebriates the torpor of the liv- er produces pain without apparent fcirrhus, or gall-ftones, or in- flammation, or confequent gofat, and in thefe epilepfy or infin- ity are often the confequence. All which will be more fuiiy treated of in the courfe of the work. I am well aware, that it is a common opinion, that the gout is as frequently owing to gluttony in eating, as to intemperance in drinking fermented or fpiritous liquors. To this I anfwer, that I have feen no perfon afflicted with the gout, who has not drunk freely of fermented liquor, as wine and water, or finall beer *, though as the difpofition to all the difeafes, which have orig- inated from intoxication, is in fome degree hereditary, a lefs quan- tity of fpirituous potation will induce the gout in thefe, who in- herit the difpofition from their parents. To which I muft add, that in young people the rheumatifm is frequently miltaken for the gout. Spice is feldom taken in fuch quantity as to do any material injury to the fyftem, flefh-meats as well as vegetables are the natural diet of mankind ; with thefe a glutton may be crammed up to the throat, and fed fat like a flailed ox ; but he will not be difeafed, unlefs he adds fpirituous or fermented liquor to his food. This is well known in the diftillerics, where the fwine, which are fattened by the fpirituous fediments of barrels, acquire diieafed livers. But mark what happens to a man, who drinks a quart of wine or of ale, if he has not been habituated to it. He lofes the ufeof both his limbs and of his imderftanding ! He becomes a temponry idiot, and has a temporary ftroke of the palfv ! And though he Qowly recovers after fome hours, is it not Sect. XXI. it. OF DRUNKENNESS. 197 not reafonable to conclude, that a perpetual repetition of To pow- erful a poifon muft at length permanently affect, him ? — If a per- fon accidentally becomes intoxicated by eating a few muihrooms of a peculiar kind, a general alarm is excited, and he is faid to be poifoned, and emetics are exhibited 5 but fo famiiiarifed are we to the intoxication from vinous fpirit, that it occafions laugh- ter rather than alarm. ^ There is however ccnfiderable danger in too haftily discontin- uing the ufe of fo ftrong a ftimulus, left the torpor of the fyftem, or paralyfis, mould fooner be induced by the omiflion than by the continuance of this habit, when unfortunately acquired. A golden rule for determining the quantity, which may with fafety be discontinued, is delivered in Sect. XII. 7. 8. 11. Definition of drunkennefs. Many of the irritative motions are much increafed in energy by internal flimulation. 2. A great additional quantity of pleafurable fenfation is occa- sioned by this increafed exertion of the irritative motions. And many fenfitive motions are produced in confequence of this in- creafed fenfation. 3. The aflbciated trains and tribes of motions, catenated with the increafed irritative and fenfitive motions, are disturbed, and proceed in confufion. 4. The faculty of volition is gradually impaired, whence pro- ceeds the instability of locomotion, inaccuracy of perception, and inconfiftency of ideas ; and is at length totally fufpended, and a. temporary apoplexy fucceeds. SECT. T9g REPETITION Sect. XXII. 1. 1. SECT. XXII. OF PROPENSITY TO MOTION, REPETITION AND IMITATION. I. Accumulation of fenforial power in hemiplegia, injleepy in cold fit of fever ; in the locomotive mu fries, in the organs offenfe. Produ- ce's fv )■ to aftion. II. Repetition by three fenforial powers. In rlimes and alliterations, in muftc, dancing, ar chit eel ure, land- [cape-painting, beauty. III. I. Perception confifls in imitation. Four kinds of imitation. 2. Voluntary. Dogs taught to dance. 3. Sen/it ive. Hence fympath y , and all our virtues. Contagious matter ef venereal ulcers, of hydrophobia, of jail-fever, of fmall-pox, produ- ced by imitation, a';d the /ex of the embryon. 4. Irritative imita- i-m. 5. Imitations refolvable into affociations . I. 1. In the hemiplegia, when the limbs on one fide have loft, their power of voluntary motion, the patient is for many days perpetually employed in moving thofe of the other. 2. When the voluntary power is fufpended during fleep, there com- ■Knees a ceafelefs flow of fenfitive motions, or ideas of imagin- ation, which compofe our dreams. 3. When in the cold fit of an intermittent fever fome parts of the fyltem have for a time continued torpid, and have thus expended lefs than their ufual . expenditure of fenforial power ; a hot fit fucceeds, with violent action of thofe vefTels, which had previoufly been quiefcent. All thefe are explained from an accumulation of fenforial power during the inactivity of fome part of the fyltem. les the very great quantity of fenforial power perpetually produced and expended in moving the arterial, venous, and glan- dular fyftems, with the various organs of digeftion, as defcribed in Section XXXII. 3. 2. there is alio a conftant expenditure of it by the action of our locomotive mufcles and organs of fenfe. Thus the thicknefs of the optic nerves, where they enter the eye, and the great cxpanuon of the nerves of touch beneath the whole the cuticle, evince the great confumption of fenforial power by th lies. -And 01: >etual mufcular actions in the com- mon offices of life, . onltantly preu .1 ving the perpendic- ularity of our bodies durii j tl day, evince a confidevable ex- penditure of : .irit of animation by our locomotive mufcles. It follows that if the e uns offenfe and muf- O cles be for a while intermitted, that fome quantity of fenforial p -1 a propensity t'> activity of fom kind en fuc from the Lncre em. Whence proceeds Sect. XXII. 2. x. AND IMITATION. i99 proceeds the irkfomenefs of a continued attitude, and of an in- dolent life. However fmall this hourly accumulation of the fpirit of ani- mation may be, it produces a propenfity to forne kind of action^ but it neverthelefs requires either defire or averfion, either pleas- ure or pain, or ibme external ftimulus, or a previous link of aC fociation, to excite the fyftem into activity ; thus it frequently happens, when the mind and body are fo unemployed as not to poffefs any of the three firft kinds of ftimuli, that the laffc takes place, and confumes the imali but perpetual accumulation of fen- forial power. Whence fome indolent people repeat the fame verfe for hours together, or hum the fame tune. Thus the poet - Onward he trudged, not knowing what he fought. And whittled as he went, for want of thought. II. The repetitions of motions may be at firft produced either by volition, or by fenfation, or by irritation, but they foon become eafier to perform than any other kinds of action, becaufe they foon become a floriated together, according to Law the feventh5 Section IV. on Animal Caufation. And becaufe their fre- quency of repetition, if as muchfenforial power be produced du- ring every reiteration as is expended, adds to the facility of their production. If a ftimulus be repeated at uniform intervals of time, as de~ fcribed in Seel:. XII. 3.3. the action, whether of our mufcies or organs of fenfe, is produced with ftill greater facility or energy* becaufe the fenforial power of aflbciation, mentioned above, is combined with the fenforial power of irritation ; that is, in com- mon language, the acquired habit affifts the power of the ftimuJuc- This not only obtains in the annual, lunar, and diurnal catena- tions of animal motions, as explained in Sect. XXXVI. which are thus performed with great facility and energy ; but in everjr lefs circle of actions or ideas, as in the burthen of a fong, or the reiterations of a dance. To the facility and diftinctnefs, with. which we hear founds at repeated intervals, we owe the pleafure, which we receive from mulical time, and from poetic time ; as defcribed in Botanic Garden, P. 2. Interlude 3. And to this the pleafure we receive from the rhimes and alliterations of mod- ern verification ; the fource of which without this key would be difficult to difcover. And to this likewife fhould be afcribed the beauty of the duplicature in the perfect tenfe of the Greek verbs, and of fome Latin ones, as tango tetegi, mordeo momordi- There is no variety of notes referable to the gamut in the beating of the drum, yet if it be performed in mulical time, it is agree: 2go REPETITION Sect. XXII. 2. i. agreeable to our ears ; and therefore this pleafurable fenfation aiuft be owing to the repetition of the divifions of the founds at certain intervals of time, or mufical bars. Whether thefe times or bars are diftbguiihed by a paufe, or by an emphafis, or accent, certain it is, that this diftinction is perpetually repeated ; other- wife the ear could not determine inftantly, whether the fuccef- fions of found were in common or in triple time. In common time there is a divifion between every two crotchets, or other notes of equivalent time ; though the bar in written mufic is put after every fourth crotchet, or notes equivalent in time •, in triple time the divifion or bar is after every three crotchets or notes equiv- alent -, fo that in common time the repetition recurs more fre- quently than in triple time. The grave or heroic verfes of the Greek and Latin poets are written in common time ; the French heroic verfes, and Mr. Anftie's humorous verfes in his Bath Guide, are written in the fame time as the Greek and Latin fes, but are one bar fhorter. The Englifh grave or heroic verfes are mcafured by triple time, as Mr. Pope's tranflation of Homer. But befides thefe little circles of mufical time, there are the greater returning periods, and the ftill more diltant chorufTes, which, like the rhimes at the ends of verfes, owe their beauty to repetition ; that is, to the facility and dillinctnefs with which we perceive founds, which we expect to perceive, or have perceived before ; or, in the language of this work, to the great- er eafe and energy with which our organ is excited by the com- bined fenforial powers of aflbciation and irritation, than by the latter fingly. A certain uniformity or repetition of parts enters the very com- pofition of harmony. Thus two octaves nearcit to each other in the icale commence their vibrations together after every fec- ond vibration of the higher tone. And where the firit, third, and fifth cempofe a chord the vibrations concur or coincide fre- quently, though lefs fo than in the two octaves. It is probable : thefe chords bear Come analogy to a mixture of three alter- nate colours in the fun's fpectrum feparated by a prifm. The pleafure we receive from a melodious iucceflion of notes ref< to the gamut is derived from another fource, viz. to the. ■1 or counteraction of antagonist, fibres. SeeBotan- 1, P. 2. Interlude 3. If to thefe be added our early af- i of agreeable ideas with certain proportions of found, I fupp , from thefe three fources fpring all the delight of rau- d by ancient authors, and fo enthufialtically cu)- Sect;. XVI. No. 10. on Inftina. d of pleafure arifini* from repetition, that is from the facility Sect. XXII. 3. 1. AND IMIi ATION. aot facility and diftinctnefs, with, -which we perceive and underftand repeated fenfations, enters into all the agreeable arts ; and when it is carried to excefs is termed formality. The art of dancing like that of mufic depends for a great part of the pleafure, it affords, on repetition ; architecture, efpecially the Grecian, confifts of one part being a repetition of another ; and hence the beauty of the pyramidal outline in landfcape-painting 5 where one fide of the picture may be faid in fome meafure to balance the other. So univerfaliy does repetition contribute to our pleafure in the fine arts, that beauty itfelf has been defined by fome writers to cenfift in a due combination of uniformity and variety. See Sea. XVI. 6. III. 1 . Man is termed by Ariftotle an imitative animal; this propensity to imitation not only appears in the actions of children, but in all the cuftoms and fafhions of the world : many thou- fands tread in the beaten paths of others, for one who traverfes regions of his own difcovery. The origin of this propenfity of imitation Ijas not, that I recollect, been deduced from any known principle ; when any action prefents itfelf to the view of a child, as of whetting a knife, or threading a needle, the parts of this ac- tion in refpect of time, motion, figure, are imitated by a part of the retina of his eye ; to perform this action therefore with his hands is eafier to him than to invent any new action, becaufe it confifts in repeating with another fet of fibres, viz. with the moving mufcles, what he had juft performed by fome parts of the retina ; juft as in dancing we transfer the times of motion from the actions of the auditory nerves to the mufcles of the limbs. Imitation therefore confifts of repetition, which we have fhewn above to be the eafieft kind of animal action, and which we per- petually fall into, when we pofiefs an accumulation of fenforial power, which is not other wife called into exertion. It has been fhewn, that our ideas are configurations of the or- gans of fenfe, produced originally in co.nfequence of the ftimu- lus of external bodies. And that thefe ideas, or configurations of the organs of fenfe, refemble in fome property a correspond- ent property of external matter ; as the parts of the fenfes of fight and of touch, which are excited into action, refemble in figure the figure of the flimulating body 5 and probably alfo the colour, and the quantity of denfity, which they perceive. As explained in Se^.t. XIV. 2. 2. Hence it appears, that our per- ceptions themfelves are copies, that is, imitations of fome prop- erties of external matter; and the propenfity to imitation is thus interwoven with our exiftence, as it is produced by the ftimuli of external bodies, and is afterwards repeated by our volitions Vol. I. C c and 2oi REPETITION Sect. XXII. 3. & and fenfaticns, and thus conflitutes all the operations of our minds. 2. Imitations refolvc themfelve's into four kinds, voluntary, fenfitive, irritative, and afTociate. The voluntary imitations aie, when we imitate deliberately the actions of others, either by mimicry, as in acting a play, or in delineating a iiower ; or in th mon actions of our lives, as in our drefs, cookery, lan- guage, manners, and even in our habits of thinking. Nut only the greateft part of mankind learn all the common arts of life by imitating others, but brute animals feem capable of acquiring knowledge with greater facility by imitating each other, than by any methods by which we can teach them ; as dogs and cats, when they are fick, learn of each other to eat grafs ; and I fuppofe, that by making an artificial dog perform certain tricks, as in dancing on his hinder legs, a living dog might be eafiiy induced to imitate them ; and that the readieft way of inftructing dumb animals is by practicing them with others of the fame fpecies, which have already learned the arts we with to teach them. The important ufe of imitation in ac- quiring natural language is mentioned in Section XVI. 7. and 8. on Inltinct. 3. The fenfitive imitations are the immediate confequences €>f pleafurc or pain, and thefe are often produced even contrary to the efforts of the will. Thus many young men on feeing cruel furgical operations become fick, and fome even feel pain in the} arts of their own bodies, which they fee tortured or wounded in others ; that is, they in fome meafure imitate by the exertions of their own fibres the violent actions, which thev vitneffed in thofc of others. In this cafe a double imitation takes j firft the obferver imitates with the extremities of optic nerve the mangled limbs, which are prefent before his cond imitation he excites fo violent action of the fibt< 1 oi • r. limbs as to produce pain in thofe parts of his own body, which he faw wounded in another. In thefe pains ;he effect Iras fome fimilarity to the caufe, thes them from thofe produced by aflbektionj as t: ins of the teeth, called tooth-edge, which are produced tion with difagreeable founds, as explained in Sect. T; of this powerful agent, imitation, in the moral led in ! . XVI. 7. as it is the foundation of ns and pleasures of the fource of all our virtues, j athy with the mif rics, or with the ares, but in an in voluntary excitation of ideas Sect. XXII. 3. 3. AND IMITATION. 203 ideas in fome rheafure fimilar or imitative of thofe, which we believe to exift in the minds of the perfons, whom we commif- erate or congratulate ? There are certain concurrent or fucceffive anions of fome of the glands, or other parts of the body, which are poffeffed of fenfarion, which become intelligible from this propeniityto imi- tation. Of thefe are the production of matter by the mem- branes of the fauces, or by the (kin, in confequence of the vene- real difeafe previoui'y affecting the parts of generation. Since as no fever is excited, and as neither the blood of fuch patients, nor even the matter from ulcers of the throat, or from cutane- ous ulcers, will by inoculation produce the venereal difeafe in others, as obferved by Mr. Hunter, there is reafon to conclude, that no contagious matter is conveyed thither by the blood-vef- fels, but that a milder matter is foraaed by the actions of the fine vefleis in thofe. membranes imitating each other. See Section XXXIII. 2.9. In this difeafe the' actions of thefe veffels pro- ducing ulcers on the throat and fkin are imperfect imitations of thofe producing chancre, or gonorrhoea ; fmce the matter produ- ced by them is not infectious, while th^ imitative actions in the hydrophobia appear to be perfect refcmblances, as they produce a material equally infectious with the original one, which indu- ced them. The contagion from the bite of a mad do* differs from other ..contagious materials, from its being communicable from other animals to mankind, and from many animals to each other •, the phenomena attending the hydrophobia are in fome degree expli- cable on the foregoing theory. The infectious matter does not appear to enter the circulation, as it cannot be traced along the courfe of the lymphatics from the wound, nor is there any fwell- ing of the lymphatic glands, nor does any fever attend, as oc- curs in the fmall-pox, and in many other contagious difeafes ; yet by fome unknown procefs the difeafe is communicated from, the wound to the throat, and that many months after the injury, fo as to produce pain and hydrophobia, with a fecretion of in- fectious ialiva of the fame kind, as that of the mad dog, which inflicted the wound. This fubjed is very intricate. — It would appear, that by cer- tain morbid a£tions of the falivay glands of the mad dog, a pe- culiar kind of faliva is produced \ which being inftilled into a wound of another animal Itimulates the cutaneous or mucous glands into morbid actions, but which are ineffectual in refpect to the production of a fimilar contagious material ; but the fali- ry glands by irritative fympathy are thrown into fimilar action, an<| 204 REPETITION Sect. XXII. 3. 4. and produce an infectious faliva fimilar to that inflilled into the wo and. Though in many contagious fevers a material fimilar to that which produced the difeafe, is thus generated by imitation •, yet there 'ire other infectious materials, which do not thus propagate themfelves, but which feem to act like flow poifons. Of this 1 id was the contagious matter, which produced the jail-fever at the aflises at Oxford about a century ago. Which, though fatal to ib many, was not communicated to their nurfes or at- tendants. In thefe cafes, the imitations of the fine veffels, as a: i. -{bribed, appear to be imperfect, and do not therefore pro- duce a matter fimilar to that, which ftimalates them j in this circumitaiice refembling the venereal matter in ulcers of the throat or fkin, according to the curious difcovery of Mr. Hun- ter above related, who iound, by repeated inoculations, that it would not infcJL Hunter on Venereal Difeafe, Part vi. ch. 1. Another example of morbid imitation is in the production of a great quantity of contagious matter, as in the inoculated fmall- pox, from a fmall quantity of it inferted into the arm. Thefe particles of contagious matter ftimuiate the extremities of the fine arteries of the fkin, and caufe them to imitate the motions by which themfelves were produced, and thus to produce a thoufand fold of a fimihr material. As different kinds of light may be fuppofed to ftimuiate parts of the retina into different kinds of motion, fo the application of different contagious matters may be believed to ftimuiate the fine terminations of the arteries into different kinds of motion, which may form matters fimilar to themfelves. This is truly difficult to underfland, but may be conceived to depend on this circumftance ; that- thofe matters, which ftimuiate other bodies into action, and the bod- ies thus fiimulated, muft poffefs fome common properties, as fpoken of in Sect. XIV. 4. See Sea. XXXIII. 2. 6. Other tances are mentioned in the Section on Generation, which (hew the probability, that the extremities of the feminal glands may imitate certain ideas of the mind, or actions of the organs of fenfe, and thus occafion the male or female fex of the embryi on. See Sect. XXXIX. 6. We come now to thofe imitations, which are not attended with fenfation. Of thefe are all the irritative ideas already ex- plained, as when the retina of the eye imitates by its action or configuration the tree or the bench, which I fhun in walking pafl without attending to them. Other examples of thefe irritative imitations are daily obfervable in common life ; thus one yawn- g perfoa fhali fet a whole company a yawning j and fome have acquired Sect. XXI. 3. 5. AND IMITATION. 205 acquired winking ,of the eyes or impediments of fpeech by imita- ting their companions without being confcioiis of it. 5. Befides the three fpecies of imitations above defcribecl there pnay be lbme aflbciate motions, which may imitate each other in the kind as well as in the quantity of their action ', but it is difficult to diftinguiih them from the aiTociations of motions treat- ed of in Section XXXV. Where the actions of ether perfons are imitated there can be no doubt, or where we imitate a pre- conceived idea by exenion of our locomotive mufcles, as in painting a dragon ; all thefe imitations may aptly be referred to the fources above described of thepropenGty to activity, and the facility of repetition ; at the fame time I do not affirm, that all thofe other apparent fenfitive and irritative imitations may not be refolvable into a/Jbciations of a peculiar kind, in wjiich certain diftant parts of fimilar irritability or fenfibility, and which have habitually acted together, may affect each other exactly with the fame kinds oi motion ; as many parts are known to fympathife in the quantity of their motions. And that therefore they may be ultimately refolvable into aiTociations of ac?non, as defcribe4 in Sea, XXXV, SECT. 206 CIRCULATORY Sect. XXIII. i. u SECT. XXIII. OF THE CIRCULATORY SYSTEM. J. *The heart and arteries have no ani eles. Veins ahfcrh the bl *el it forwards, and &jl end the heart ; contraction of ?s. Vena portarum. II. Qlanqj which om the blood. With long necks, with jhort necks. III. Abhrbent fyftem. IV. Heat given oiit fr-om glandular fe- cretions. J es colour in the lungs ana in the glands and en rj, V. Blood is abforbedby veins , as chyle by lacteal vejfels^ other --wife they could not join their jlr earns. VI. Tivo hinds of Jlim- ulus, agreeable and difagreeable. Glandular appetency. Glands c riyinaliy pojfejfed [enfation* I. I. We now ftep forwards to illuftratefome of the phenom- ena of difeafes, and to trace out their moft efficacious methods of cure ; and mail commence the fubjecl with a ihort defcrip- lion of the circulatory fyfttm. As the nerves, whofe extremities form our various organs of fenic and mufcles, are all joined, or communicate, by means of brain, for the convenience perhaps of the diitribu: ion of a fub- tile ethereal fluid for the purpofe of motion ; fo all thofe veilW of the , « hich carry the proffer fluids for the purpofes of nu- trition, communicate with each other by the heart. The heart and arteries are hollow mufcles, and are therefore indued with power of contraction in confequence of ftimulus, 3ik-e all other mufcular fibres ; but, as they have no antagonist mufcles, the cavities of the veffels, which they form, would re- main for ever clofed, after they have contracted themfelves, un lefs fome extraneous power be applied to again diilend th This extraneous power in refpect to the heart is the current o blood which is itually abforbed by the veins from the variou glands and capillaries, an i pufbed into the heart by a power prob- ably very Gmilar to that, which raifes the fap in vegetables i g, which, according to Dr. Hale's experiment on th {lump of a vine, exerted a force equal to a column of wate above twenty feet high. This force of the current of blood i the veins is partly produced by their abforbent, power, exert- *_ at tin ming of every fine ramification ; which may b conceived to be a n as the mouths of th la&eals and lymphatics abforb chyle and lymph. And parti lifted compreffionby the pulfations of their gener at arteries ; by which the blood is perpetually pro- pelled \ Sect. XXIII. i. i. SYSTEM. 207 pelled towards the heart, as the valves in many veins^ and the ab- forbent mouths in them all, will not fuffer it to return. ' The blood, thus forcibly injected into the chambers of the heart, diitends this combination of hollow muicles ; till by the; ftimulus of detention they contract themfelves; and, pu'hing forwards the blood into the arteries, exert fufficient force to overcome in lefs than a fecond of time the vis inertiae, and perhaps fome elafticity, of the very extenfive ramifications of the two great fyftems of the aortal and pulmonary arteries. The power neeef- fary to do this in fo fhort a time rauft be considerable, and has been variouily eftimated by different phyfiologifts. The mufcuiar coats of the arterial fyftem are then brought into action by the flimulus of diilention, and propel the blood to the mouths, or through the convolutions, which precede the fecretory apertures of the various glands and capillaries. In the veffels of the liver there is no intervention of the heart ; but the vena portarum, which doer, the office of an artery, is dif- tended by the blood poured into it from the mefenteric veins, and is by this diilention {Simulated to contract itfeif, and propel the blood to the mouths of the numerous glands, which compofe that vifcus. The power of abforption in vegetable roots was (hewn by tl experiments of Dr. Hales on vine-dumps to be equal to the pref- fure of thirty-eight inches of quickfilver. Veg. Staticks, p. 107. and from the experiments of Mr. Cooper, who tied the thoracic ducts of living dogs, it appeared, that the abforbent power of the lacteals and lymphatics always burft the receptaculum chyli. Mr. Cooper adds, "The contractile powers of the ab for bents are proved by thefe experiments to be very flrong 5 for it appears, that their action is fufficient to occafion a rupture of their coats. It is true, that the receptaculum chyli, which was the part bro- ken, is thinner and lefs capable of reliltance than the thoracic duct j yet it is able to bear the preflure of a column of quick- filver more than two feet in height. The force therefore exert- ed by the abforbents mull be acknowledged to be greater than that of fuch a column of mercury ; more efpecially when it is remembered, that living parts will refill a force, which will read- ily tear them when dead." Medical Refearches. London. 1798, p. 1 10. Dr. Hales made experiments fimilar to thofe on the flumps of vines above mentioned, by ooenii:? the crural arteries of a hone, a dog, and a fallow deer, by applying mercurial gauges to meafure the projectile impetus of their blood ; and found that of the vine-Hump to be five times greater than the force of the blood in the great crural artery of a horfe, fevea times greater than acS CIRCULATORY Sect. XXlII. 2. 1. than that of a dog, and eight times greater than that of a fallow dee. The power of abforption in the animal fyftem exerts a force fuperior to that of the heart, though perhaps with lefs velocity ; 2nd thus removes all difficulty of accounting for the circulation in the veins and abforbents ; and confequenrly of the circulation in the aortal arteries of fifh, and in the vena portaru m, or the bile-fecreting artery of the liver of quadrupeds. II. 1. The glandular fyftem of veffels may be divided into thofe, which take fome fluid from the circulation ; and thofe, which give fomething to it. Thofe, which take their fluid from the cir- culation, are the various glands, by which the tears, bile, urine, perfpiration, and many other fecretions are produced •, thefe glands probably con lift of a mouth to fele£t, a belly to digeft, and an excretory aperture to emit their appropriated fluids ; the blood is coaveyed by the power of the heart and arteries to the mouths of thefe glands, it is there taken up by the living power of the gland, and carried forwards to its belly, and excretory ap- erture, where a part is feparated, and the remainder abforbed by the veins for further purpofes. Some of thefe glands arc furnifhed with long convoluted necks or tubes, as the feminal ones, which are curioufly fcen when injected with quickfilver. Others feem to confifl of fhorter tubes, as that great congeries of glands, which conftitute the liver, and thofe of the kidneys. Some have their excretory apertures' opening into refervoirs, as the urinary and gall-bladders. And others on the external body, as thofe which fecrete the tears, and perfpirable matter. Another great fyftem of glands, which have very (hort necks, are the capillary veffels ; by which the infcnflble perfpiration is fecreted on the fkin ; and the mucus of various confiftenceSj which lubricates the interftices of the cellular membrane, of the mufcular fibres, and of all the larger cavities of the body. From the want of a long convolution of veffels fome have doubted, whether thefe capillaries mould be confidered as glands and have been led to conclude, that the perfpirable matter rather ex- uded than was fecreted. But the fluid of perfpiration is not Am- ple water, though that part of it, which exhales into the air may be fuch ; for there is another part of it, which in a (late of health is abforbed again ; but which, when the abforbents are difeafed, remains on the furface of the (kin, in the form of fcurf, or indu- rated mucus. Another thing, which (hews their fimihtude to other glands, is their fenfibility to certain affections of the mind 5 ss is (czn in the deeper colour of the fkin in the blufh of iliame, the greater paleneft of it from fear. III. Another &ect. XXIII. 3- SYSTEM, 209 III. Another feries of glandular veiTsls is called the abforbent fyfte'm ; thefe open their mouths into all the cavities, and upon ali tho;e furfaces of the body, where the excretory apertures of the other glands pour out their fluids... The mouths of the ab- forbent fyilem drink up a part or the whole of thefe fluids, and carry them forwards, -by their living' power to their refpeclive glands, which are called conglobate glands. • .There thefe fluids undergo fome change, before they pafs on into the circulanon ; but if they are very acrid, the conglobate gland fwells, and fome- times fuppurates, as in inoculation of the fmall-pox, in the plague, and in venereal abforptions ; at other times the fluid may per- haps continue there, till it undergoes fome chemical change, that renders it lefs noxious ; or, what is more likely, till it is regurgi- tated by the retrograde motion of the gland in fpontaneous iVeats or diarrhoeas^ as difagreeing food is vomited from the ftomach. , The powers. of abibrpiion are (hewn in No. I. of this Section, both thofe of the blood and of the chyle of animals, and of the fap-juice of vegetables, to be much greater than- has commonly been conceived. To, which may be added, that the moving force of the chyle in the receptaculum chyli and. thoracic duel' muft be equal to the moving force of the blood in the fubclavian vein, as otherwife the chyle could not enter into that vein, un- lefs it be fuppofed to poflefs.a fyflole and diaftole near the heart ; which alfo affords an argument to (hew., that the progress of the blood in the veins, and that of the chyle in the abforbent fy (rem, originates from a fimiJar caufe, that of their abforptive powers. , IV. As all the fluids, that pafs through thefe glands, and cal ; iry veffels, undergo a chemical change, acquiring new com- binations, the matter of heat is at the fame time given out ; this is apparent, fince whatever increafes infenfible penpiration, in- creaies the heat of the fkin ; and when the action of thefe ve-ffeis k much increafed but for a moment, as in blaming, 3 vivid heat on, the fkin is the immediate confequence. So when great bil- ious fecretions, or thofe of any other gland, are produced, heat is generated in the part in proportion to the quantity of the fe- cretion. . The heat produced on the fkin by blaming may -be thought by fome too fudden to be pronounced a chemical effecl:* as the fermentations or new combinations taking place in a fluid is in general a flower procefs. Yet are there many chemical mixtures in which heat is given out as initantaneoufly ; as in folutions of metals in acids, or in mixtures of elfential oils and acids, as of oil of cloves and acid of nitre. So the bruifed parts of an un- ripe apple become aim oil mttantaneouily fweet •, and if the chem- ico-animil procefs of digeition be flopped for but a moment, a* Vol. I, D d bv 21* CIRCULATORY Sect. XXIII. £ by fear, or even by voluntary eructation, a great quantity of air is generated, by the fermentation, which inftantly fucceeds the ftop of digeftion. By the experiments of Dr. Hales it appears, that an apple during fermentation gave up above fix hundred times its bulk of air ; and the materials in the ftomach are fuch, and in fuch a fituation, as immediately to run into fermentation, ivhen digeftion is impeded. As the blood paiTes through the fmall vefTels of the lungs, v/hich conned: the pulmonary artery and vein, it undergoes a change of colour from a dark to a light red ; which maybe term- ed a chemical change, as it is known to be effected by an ad- mixture of oxygene, or vital air 5 which, according to a difcov- ery of Dr. Prieftley, pauses through the moift membranes, which conftitute the fides of thefe vefTels. As the blood paiTes through the capillary vefTels, and glands, which connecl the aorta and its various branches with their correfpondent veins in the ex- tremities of the body, it again lofes the bright red colour, and undergoes fome new combinations m the glands or capillaries, in which the matter of heat is given out from the fecreted fluids. This prccefs therefore, as well as the procefs of refpiration, has fome analogy to ccmbuilion, as the vital air or oxygene feems to become united to fome inflammable bafe, and the matter of heat efcapes from the new acid, which is thus produced. V. After the blood has palled thefe glands and capillaries, and parted with whatever they chofe to take from it, the re- mainder is received by the veins, which are a fet of blood-abforb- ing vefTels in general correfpending with the ramifications of the arterial fyftem. At the extremity of the fine convolutions of the glands the arterial force ceafes ; this in refpecr, to the capillary vefTels, which unite the extremities of the arteries with the com- mencement of the veins, is evident to -The eye, on viewing the tail of a tadpole by means of a folar, or even by a common mi- crofcope, for globules of blood are feen to endeavour to pafs, and to return again and again, before they become abforbed by the mouths of the veins \ which returning of thefe globules evinces, that the arterial force behind them has ccafed. The veins are furnifhed with valves like the lymphatic abforbents j and the great trunks of the vi and of the lacleals and lymphatics, join ' Tore the ingrefs of their fluids into the left cham- ber of the heart ; both which evince, that the blood in the veins, and the lymph and chvle in the lacteals and lymphatics, are car* ried on by a fimilar force \ oiherwife thefftream, which was pro* pelled with a lei er, could not enter the vefTels, which con- tained the ftream propelled with a greater power. From whence it appear^, that the ireins area fyftem of vefiels abforbing blood, as Sect. XXIII. 6. SYSTEM. a 1 1 as the lacleals and lymphatics are a fyfteni of veiTels abforbing chyle and lymph. See Sect. XXVII. i . VI. The movements of their adapted fluids in the various veflels of the body are carried forwards by the actions of thofe veiTels in ccnfequence of two kinds of ftimulus, one of which may be compared to a pleafurable fenfation or deiire inducing the vef- {el to feize, and, as it were, to f wallow the particles thus felecl> ed from the blood ; as is done by the mouths of the various glands, veins, and other abibr bents, which may be called glandu- lar appetency. The other kind of ftimulus may be compared to difagreeable fenfation, or averfion, as when the heart has re- ceived the blood, and is fiimuiated by it to pufh it forwards into the arteries ; the fame again ftimulates the arteries to contract, ai;d carry forwards the blood to their extremities, the glands and capillaries. Thus the mefenteric veins abforb the blood from the interlines by glandular appetency, and carry it for- ward to the vena portarum ; which acting as an artery con- tracts itfelf by difagreeable ftimulus, and pufnes it to its ramified extremities, the various glands, which conftitute the liver. It feems probable, that at the beginning of the formation of thefe veflels in the embryon, an agreeable fenfation was in real- ity felt by the glands during fecretion, as is now felt in the a£fc of f wallowing palatable food ; and that a difagreeable fenfation •was originally felt by the heart from the diftention occafioned by the blood, or by its chemical ftimulus ; but that by habit thefe are all become irritative motions ; that is, fuch motions as do not affect the whole fyftem, except when the veflels are ^ifeafed by inflammation. SECfc Zi? ©F THE SALIVA Sect. XXIV. k S E C T. XXIV. OF THE SECRETIONS OF SALIVA, AND OF TEARS, ANP OF TH£ LACRYMAL SACK. I. Secretion of faliva increafed by mercury in the Hood. I. By the focd in the mouth. Drynejs of the mcuth not from a deficiency of faliva. 2. By fenfative ictecs. 3. By volition. ' 4. By diflafle- ful fubjlances. It is fee ret ed in a dilute and j aline fate. It then becomes more vifcid. t;. By idea. \ftaftefut fubjlances. 6. By naufea. 7. By Qverfioq.' 8- By catenation with Jiimulating fubjlances in the ear. II. i. Secretion of tears lefs in flee p. J* ram jlimulation of their excretory duct. 2. Lacrymal fark is a gland. 3. Its ufes. 4. Tears are fee ret ed, when the nafal duel is Jlimulated. 5. Or when it is excited by fenjation. 6. Or by volition* 7. The lacrymal Jack can regurgitate its contents into the eye. 8. More tears are fecreted by affectation with the irri* taiicn of the nafal duel of the lacrymal Jack, than the puntla lacry-* tnalia can imbibe* Of the gout in the liver andfiomach, I. The falival glands drink up a certain fluid from the cir- cumfluent blood, and pour it into the mouth. They are fome- times (limulated into action by the blood, that furrounds their origin, or by fome part of that heterogeneous fluid : for when mercurial fairs, or oxydes, are mixed with the blood, they itim- ulatethefe glands into unnatural exertions ; and then an unufuai quantity of faliva is feparated. 1. As the faliva fecreted by thefe glands is molt wanted during the maftication of our food, it happens, when the terminations* of their duels in the mouth are ichhulated into action, the fali- val glands themfelves are brought into increafed action at the fame time by aflbciation, andfeparate a greater quantity of their juices from the blood ; in the fame manner as tears are produ- ced in greater abundance during the ftimulus of the vapour of onions, or of any other acrid material in the eye. The faliva is thus naturally poured into the mouth only du- ring the tlimulus of our loodin mafticaticn 5 for when there is too great an exhalation of the mucilaginous fecretion from the membranes, which line the mouth, or too great an absorption of it, the mouth becomes dry, though there is no deficiency in the quantity of faliva ; as in thole who fleep with their moutl^ open, and in fome fevers.' 2. Though during the maftication of our natural food the fa- Jivul glands are excited into aclion by the Tumulus on their ex- cretory $ear. XXIV. i. 3. AND TEARS. 213 cretory duets, and a due quantity of faliva is feparated from the biccd* and poured into the mouth ; yet as this maftication of our /ood is always attended with a degree ofpleaiurej and that pleafurab.le fenfatio.u is alio connected with our ideas of certain kinds of aliment ; it follows, that when theie ideas are repro- duced, the pieafurable fenfation arifes along with them, and the falival glands are excited into action, and fill the mouth with fat liva from this fenfitive aflbciation, as is frequently feen in dogs, who Haver at the light of food. 3. We have alio a voluntary power over the action of thefs falival glands, for we can at any time produce a flow of faliva into our mouth, and f'pit out, or f wallow it at will. 4. If anv verv acrid material be held in the mouth, as the root of pyrethrum, or the leaves of tobacco, the falival glands are ftimulated into flronger action than is natural, and thence fer ctete a much larger quantity of faliva \ which is at the fame time more vifcid than in its natural irate ; becaufe the lymphat- ics, that open their mouths into the ducl:s of the falival glands., and on the membranes, which line the mouth, are like wife ftim- ulated into ftronger action, and abforb the more liquid parts of she faliya with greater avidity ; and the remainder is left both in greater quantity and more vifcid. The increaied abforption in the mouth by fome ftimulating fubdances, which are called aftringents, as crab-juice, is evident from the inftant drynefs produced in the mouth by a fmaii quantity of tiicrm As the extremities of the glands are of exquiiite tenuity, as appears by their difficulty of injection, it was necellary for them tp fecrete their fluids in a very dilute irate ; and, probably for the jmrpofe of ftimulating them into action, a quantity of neutral /alt is likewife fecreted or formed by the gland. This aqueous and faline part of all fecreted fluids is again reabforbed into the habit. More than half of fome fecreted fluids is thus imbibed from the refervoirs, into which they are poured \ as in the urin- ary bladder much more than half of what is fecreted by the kid- neys becomes reabforbed by the lymphatics, which are thickly qifperfed around the neck of the bladder. This feems to be the purpofe of the urinary bladders of hih, as otherwife fuch a re- ceptacle for the urine could have been of no ufe to an animal jmmerfed in water. 5. The idea of fubdances difagrccably acrid will alio produce a quantity of faliva in the mouth ; as when we fmellvery putrid vapours, we are induced to ipit out our faliva, as if fomething diiagreeable was actually upon our palates. <&. When difagreeabic food in the itumach produces naufea„ *i4 OF THE SALIVA Sect. XXIV. i. y a flow of faliva is excited in the mouth hy aflbciation ; as effort* to vomit are frequently produced by disagreeable drugs in the mouth by the fame kind of aflbciation. 7. A preternatural flow of faliva is Hkewife fometimes occa- iioned by a difeafe of the voluntary power.; for if we think about our faliva, and determine not to f wallow it, or not to fpit it out, an exertion is produced by the will, and more faliva is fecreted againit our wifh ; that is, by our averfion, which bears the fame analogy to defire, as pain does to pleafure •, as they are only modifier-: ions of the fame difpoiition o.r the fenforium. See I ifsIV. 3. 2. 1. 8. The quantity of faliva may alfo be increafed beyond what is natural, by the catenation of the motions of thefe glands with ler motions, or fenfations, as by an extraneous body in the eir ; of which I have known an initance ; or by the application of ftizolobium, fiiiqua hirfuta, cowhage, to the feat of the paro- tis, as fome writers have affirmed. II. 1. The lacrymal gland drinks up a certain fluid from the circumfluent blood, and pours it on the ball of the eye, on the upper part of the external corner of the eyelid . Though it may perhaps be flimulated into the performance of its natural action by the blood, which (unrounds its origin, or by fome part of that heterogeneous fluid ; yet as the tears fecreted by this gland are more wanted at fome times than at others, its fecretion is varia- ble, like that of the faliva above mentioned, and is chiefly pro- duced when its excretory duel is flimulated ; for in our common Step there feems to be little or no fecretion of tears; though they are occafionally produced by our fenfations in dreams. 'Thus when any extraneous material on the eye-ball, or the drvnefs of the external covering of it, or the coldnefs of the air, or the acrimony of fome vapours, as of onions, ftimulates the excretory duel: of the lacrymal gland, it difcharges its contents upon the ball ; a quicker fecretion takes place in the gland, and abundant tears fucceed, to moiflen, clean, and lubricate the eye. Thefe by frequent nictitation are diflfufed over the whole ball, and as the external angle of the eye in winking is clofed fooner than the internal angle, the tears are gradually driven forwards, and downwards from the lacrymal gland to the puntla lacryma- lia. 1. The lacrymal facie, with its punct? lacrymalia, and its nafal duc"t, is a complete gland •, and is (insular in this refpecf, that it neither derives its fluid from, nor difror^es it into the circulation. 'J he fimplicity of the ftructure ol thi:, gland, and both the ex- tremities cf it being on the furface of the body, makes it well ■worthy our minuter obfervation \ as the actions of more intricate and Sect. XXIV. 2. 3. AND TEARS. 215 and concealed glands may be better underftood from their anal- ogy to this. 3. This fimple gland confifts of two abforbing mouths, a bel- ly, and an excretory duct. As the tears are brought to the in- ternal angle of the eye, thefe two mouths drink them up, being ftimulated into action by this fluid, which they abforb. The belly of the gland, or lacrymal lack, is thus filled, in which the faline part of the tears is abforbed, and when the other end of the gland, or nafal duel, is ftimulated by the drynefs, or pained by the coldnefs of the air, or affected by any acrimoneous duft cr vapour in the noftrils, it is excited into action together with the fack, and the tears are difgorged upon the membrane, which lines the noftrils ; where they ferve a lecond purpofe to moiften, clean, and lubricate^ the organ of fmell. 4. This gland, when its nafal duct is ftimulated by any very acrid material, as the powder of tobacco, or volatile fpirits, not on- ly difgorges the contents of its belly cr receptacle (the lacrymal fack), and abforbs haftily all the fluid, that is ready for it in the corner of the eye 5 but by the aflociation of its motions with thofe of the lacrymal gland, excites that alfo into increafed ac- tion, and a large flow of tears is poured into the eye. 5. This nafal duct is likewife excited into ftrong action by fenfitive ideas, as in grief, or joy, and then alfo by its aflbciations with the lacrymal gland it produces a great flow of tears with- out any external ftimulus 5 as is more fully explained in Sect. XVI. 8. on Inftinct. 6. There are fome, famous in the arts of exciting companion, who are faid to have acquired a voluntary power of producing a> flow of tears in the eye ; which, from what has been faid in the fection on Inftinct above mentioned, I {hould fufpect, is perform- ed by acquiring a voluntary power over the action of this nafal duct. 7. There is another circumftance well worthy our attention, that when by any accident this nafal duct is obftructed, the lac- rymal fack, which is the belly or receptacle of this gland, by flight prefFure of the finger is enabled to difgorge its contents again into the eye \ perhaps the bile in the fame manner, when the biliary ducts are obftructed, is returned into the blood by the veflels which fecrete it ? 8. A very important though minute occurrence muft here be obferved, that though the lacrymal gland is only excited into ac- tion, when we weep at a diftrefsful tale, by its aflbciation with this nafal duct, as is more fuiljr explained in Sect. XVI. 8 ; yet the quantity of tears fecreted at once is more than the puncta lacry- rnalia can readily abforb ; which {hews that the motions accafwned h 7 ii Of the saliva, &£ Sect.xxiv. 2. T. by aJLciathns are frequently more energetic than the original motioftri b i "..which they luere occq/toned. Which we ihall have occafion to mention hereafter, to illuftrate, why pains frequently exift in a part diftant from the cauie oF them, as in the oilier end of the urethra, when a (tone ftimulates the neck of the bladder. And hy infiammaiicns frequently arife in parts diftant from their c iufej as the gutta rofea of drinking people, from an inflamed liver. The inflammation of a part is generally preceded by a torpor or quiefcence of it ; if this exifts in any larger congeries of glands, as in the liver, or any membranous part, as the ftomach, pain is produced and chillinefs in confequence of the torpor of the veflels. In this fituation fometimes an inilammation of the parts' iucceeds the torpor ; ?t other times a diftant more fenHble partbe~, comes inflamed •, whofe actions have previoufly been aflociated with it : and the torpor of the flrft part ceafes. This I appre- hend happens, when the gout of the foot fucceeds a pain of the' biliary duel, or of the ftomach. . Laftly, it fometimes happens/ that the pain of torpor exifts without any confequent inflamma- tion of the affected part, or of any diftant part afTbcbied with it/ as in the membranes about the temple and eye-brows in hemi- crania, and in tbo'e pains, which occafion cenvuluons; if this happens to gouty people, when it affects the liver, I fuppofe epi- leptic fits are produced y and, when it affects the ftomach, death is the confequence. In thefe cafes the pulle is weak, and the extremities cold, and fuch medicines as ftimula'te the quicfcen*: parts into action, or which induce inflammation in them, or in anv diitant part, which is aflociated with them, cures the pres- ent pain cf torpor, and faves the patieuL I have twice iztn a gouty inflammation of the liver, attended with jaundice ; the patients after a few days were both of them affected with cold fits, like ague fits, and their feet became a fected with gout, and the inflammation of their livers ceajed. It is probable, that the uneafy fenfations about the ftomach, and indip"eftion, which precedes gouty paroxyfms, are generally- ow-* ing to torpor or flight inflammation of the liver, and biliary ducts •, but where great pain with continued Gqknefs, with feeble pulfe, and fenfation of cold, affect the ftomach in patients debil- itated by the gout, that it is a torpor of the ftomach itfelf, and deftroys the patient from the great connexion of that vifcus with the vital organs. See Sect. XXV. 17. SECT. Sect. XXV. i. OF THE STOMACH, Sec, 217 SECT. XXV. OF THE STOMACH AN© INTESTINES. X. Of fw allowing our food. Ruminating animals. 2. Aclion of the ftomach. 3 . Aclion of the inteflines. Irritative motions con* tie bled with thefe. 4. Effects of repletion. 5. Stronger aclion of the fomach and inteflines from more flimulating jood. 6. Their aclion inverted by fill greater flimuli. Or by difguflful ideas. Or by volition. 7. Other glands frengthen or invert their motions by fympathy. 8. Vomiting performed by intervals. 9. Inverfloti of the cutaneous abforbents. 10. Increafed fecreii-ya of bile and pancreatic juice. 1 l. Inverfion of the lacleals. 12. And of the bile-duels. 13. Cafe of a cholera. 14. Farther ac- count of the inverfion of lacleals. 15 Iliac paffion. Valve of the colon. 16. Cure of the iliac paffion. 17. Pain of gall- fone diflinguifljed from pain of the fomach. Gout of the fomach from torpor ', from inflammation. Intermitting pulfe owing to i;i~ digeflion. To overdofe of foxglove. Weak pulfe from emetics* Death from a blow on the fomach. From gout of theflomach, 1. The throat, ftomach, and inteflines, may be considered as one great gland ; which like the lacrymal fack above mentioned, neither begins nor ends in the circulation. Though the aft of mafticating our aliment belongs to the fenfitive clafs of motions, for the pleafure of its tafte induces the mufcles of the jaw into action ; yet the deglutition of it when mafticated is generally, if not always, an irritative motion, occafioned by the application of the food already mafticated to the origin of the pharinx ; in the fame manner as we often fwallowour fpittle without attend- ing to it. The ruminating clafs of animals have the power to invert the motion of their gullet, and of their fir ft ftcmach, from the ftim- Ulus of this aliment, when it is a little further prepared; as is '•their daily practice in chewing the cud $ and appears to the eye of any one, who attends to them, whillt they are employed in this fecond maftication of their food. 2. When our natural aliment arrives into the ftomach, this or- gan is ftimulated into its proper vermicular a£t'ion ; which be- ginning at the upper orifice of it, and terminating at the lower one, gradually mixes together and puihes forwards the digefting materials into the inteitine beneath it. At the fame time the glands, that fupnly the gaftric juices hich are neceiTary to promote the chemical part of the procefs Voi, I. \ Ee of t 2r8 OF THE STOMACH Sect. XXV. p of digeftion, are ftimulated to difcharge their contained fluids, and to feparate a further fupply from the blood-veflels : and the lacteals or lymphatics, which open their mouths into the ftomach, are ftimulated into action, and take up fome part of the digefting ©■.aterials. 3. The remainder of thefe digefting materials is carried for- wards into the upper inteflines, and ftimulates them- into their periftahic motion fimilar to that of the ftomach ; which contin- ues gradually to mix the changing materials, and pafs them along through the valve of the colon to the excretory end of this great gland, the fphincter ani. The digelting materials produce a flow of bile, and of pancre- atic juice, as they pafs along the duodenum, by ftimulating the excretory duels of the liver and pancreas, which terminate in that inteftine : and other branches of the abforbent or lymphatic fyftem, called lacteals, are excited to drink up, as it pafles, thofe parts of the digefting materials, that are proper for their purpofc, by its ftimulus on their mouths. 4. When the ftomach and inteflines are thus filled with their proper food, not only the motions of the gaftric glands, the pan- creas, liver, and lacteal vefTels, are excited into action \ but at the fame time the whole tribe of irritative motions are exerted with greater energy, a greater degree of warmth, colour, plump- nefs. and moifture, is given to the fkin from the increafed action cf thofe glands called capillary vefTels ; pleafurable fenfation is excited, the voluntary motions are lefs eafily exerted, and at length fufpended ; and fleep fucceeds, unlefs it be prevented by the ftimulus cf furrounding objects, or by voluntary exertion, or by an acquired habit, which was originally produced by one or other of thefe circumftances, as is explained in Sect. XXI. on Drunkermefs. At this time al fo, as the blood-veflels become replete with chyle, more urine is feparated into the bladder, and lefs of it is reabforbed ; more mucus poured into the cellular membranes, and lefs of it reabforbed : the pulfe becomes fuller, and fofter, and in general quicker. The reafon why lefs urine and cellular mucus is abforbed after a full meal with fufficient drink is owing to the bleod-veflels being fuller : hence one means to promote ab- sorption is to decreafe the refiftance by emptying the vefTels by 1 : eftion. From this decreafe^ abforption the urine becomes pale as well as copious, and the lkin ajmears plump as well as florid. By daily repetition of thefe moknent" they all become con- nected together, and make a diurnal cirds of irritative action, anl Sect. XXV. 5. AND INTESTINES. 219 and if one of this chain be difturbed, the whole is liable to be put into diforder. See Set!:. XX. on Vertigo. 5. When the flomach and intettines receive a quantity of food, whofe ftimulus is greater than ufual, all their motions, and thofe of the glands and lymphatics, are flimulated into ftronger action than ufual/ and perform their offices with greater vigour and in lefs time : fuch are the effects of certain quantities of fpice or of vinous (pint. 6. But if the quantity or duration of thefe ftimuli are ftill further increafed, the ftomach and throat are ftimulated into a motion, whofe direction is contrary to the natural one above de- scribed ; and they regurgitate the materials, which they contain, inftead of carrying them forwards. This retrograde motion of the ftomach may be compared to the ftretchings of wearied limbs the contrary way, and is well elucidated by the following experiment. Look earneftly for a minute or two on an area an inch fquare of pink filk, placed in a ftrong light, the eye becomes fatigued, the colour becomes faint, and at length vaniihes, for the fatigued eye can no longer be ftimulated into direct motions ; then on clofing the eye a green Spectrum will appear in it, which is a colour directly contrary to pink, and which will appear and dis- appear repeatedly, like the efforts in vomiting. See Section XXIX. 1 1. Hence all thofe drugs, which by their bitter or aftringent ftim- ulus increafe the action of the ftomach, as camomile and white vitriol, if their quantity is increafed above a certain dofe become emetics. Thefe inverted motions of the ftomach and throat are gener- ally produced from the ftimulus of unnatural food, and are attend- ed with the fenfation of naufea or ficknefs : but as this fenfation is again connected with an idea of the diftafteful food, which induced it ; fo an idea of naufeous food will alfo fometimes ex- cite the action of naufea ; and that give rife by aflbciation to the inverfion of the motions of the ftomach and throat. As fome, whohave had horfe-fle{h or dogs-flefh given them for beef or mut- ton, are faid to have vomited many hours afterwards, when they have been told of the impofition. I have been told of a perfon, who had gained a voluntary com- mand over thefe inverted motions of the ftomach and throat, and fupported himfelf by exhibiting this curiolity to the public. At thefe exhibitions he fwallowed a pint of red rough goofeberries, and a pint of white fmooth ones, brought them up in fmall par- cels into his mouth, and reftored them feparately to the Specta- tors, who called for red or white as they pleafed, till the whole Wrere redelivered. * 7- At (W ^20 OF THE STOMAtH Sect. XXV. 7. 7. At the fame time that thefe motions of the ftomach and throat are ftimulated into inverfion, fome of the other irritative motions, that had acquired more immediate connexions with the ftomach, as thofe of the gaftric glands, are excited into ftronger action by this affociation ; and fome other of thefe motions, which are more eafily excited, as thofe of the gaftric lymphatics, are inverted by their afibciation with the retrograde motions of the ftomach, and regurgitate their contents, and thus a greater quantity of mucus, and of lymph, or chyle, is poured into the ftomach, and thrown up along with its contents. 8. Thefe inverfions of the motion of the ftomach in vomiting are performed by intervals, for the fame reafbn that many other motions are reciprocally exerted and relaxed ; for during the time of exertion the ftimulus, or fenfation, which caufed this ex- ertion, is not perceived ; but begins to be perceived again, as foon as the exertion ceafes, and is fome time in again producing its effect. As explained in Sect. XXXIV. on Volition, where it is {hewn, that the contractions of the fibres, and the fenfation of pain, which occafioned that exertion, cannot exift at the fame time. The exertion ceafes from another caufe alfo, which is the exhauftion of the fcnforial power of the part, and thefe two caufes frequently operate together. 9. At the times of thefe inverted efforts of the ftomach not on- ly the lymphatics, which open their mouths into the ftomach, but thofe of the fkin alfo, are for a time inverted : for fvveats are fometimes pufhed out during the efforts of vomiting without an increafe of heat. 10. But if by a greater ftimulus the motions of the ftomach are inverted ftill more violently or more permanently, the duod- enum Has its periftaltic motions inverted at the fame time by their affociation with thofe of the ftomach ; and the bile and pan- creatic juice, which it contains, are by the inverted motions brought up into the ftomach, and difcharged along with its con- tents y while a great quantity of bile and pancreatic juice is pour- ed into this inteftine ; as the glands, that fecrete them, are by their afibciation with the motions of the inteftine excited into ftronger action than ufual. 1 1. The other inteftines are by afibciation excited into more powerful action, while the lymphatics, that open their mouths into them, fuffer an inverfion of their motions correfponding with the lymphatics of the ftomachj and duodenum; which with a part of the abundant fecretion of bile is carried downwards, and contributes both to ftimulate the bowels, and to increafe the quan- tity of the evacuations. This inverfion of the motion of the lym- ics appears from the quantity of chyle, which comes away » by Sect. XXV. 12. AND INTESTINES. 221 by floods ; which is other wife abforbed as foon as produced, and by the immenfe quantity of thin fluid, which is evacuated along with it. 12. But if the tumulus, which inverts the ftomach, be fall more Dowerful, or more permanent, it fometimes happens, that the motions of the biliary glands, and of their excretory ducts, are at the feme time inverted, and regurgitate '.heir contained bile into the blood-veiiels, as appears by the yellow colour of the flein, and of the urine ; and it is probable the pancreatic fecretion may fuffer an inverQon at the fame time, though we have yet no mark by which this can be afcertaincd. 1 <5. Mr. ate two putrid pigeons out of a cold rnVeon- pye, and drank about a pint of beer and ale along with them, and immediately rode about five miles. He was then feized with vomiting, which was after a few periods fucceeded by purg- ing ; thefe continued alternately for two hours \ and the purg- ing continued by intervals for fix or eight hours longer. Du- ring this time he could not force himfelf to drink more than one pint in the whole ; this great inability to drink was owing to tht naufea, or inverted motions of the ftomach, which the volunta exertion of fwallowing could feldom and with difficulty over- come ; yet he difcharged in the whole at lead fix quarts j whence; came this quantity of liquid ? Firft, the contents of the ftomach were emited, then of the duodenum, gall-bladder, and pancreas, by vomiting. After this the contents of the lower bowels ; then the chyle, that was in the Ja£teal vefTels, and in the receptacle of chyle, was regurgitated into the inteftines by a retrograde mo- tion of thefe vefleis. And afterwards the mucus difpofited in the cellular membrane, and on the furface of all the other mem- branes, feems to have been abforbed u and with the fluid abforb- ed from the air to have been carried by their refpeclive lymphat- ic branches by the increafed energy of their natural motions, and down the vifceral lymphatics, or lacteals, by the inverfion of their motions. 14. It may be difficult to invent experiments to demonftrate the truth of this inverfion of fome branches of the abforbent fyf- tem, and increafed abforption of others 5 but the analogy of thefe vefTels to the inteftinal canal, and the fymptoms of many difeafes, render this opinion more probable than many other received opinions of the animal economy. In the above in fiance, after the yellow excrement was voided, the fluid ceafed to have any fmell, and appeared like curdled milk, and then thinner fluid, and fome mucus, were evacuated j did not thefe feern to partake of the chyle, of the mucous fluid frpm all the cells of the body, and laftly, of the atmofpheric moif- • ture ? 222 OF THE STOMACH Sect. XXV. ij, tare ? All tixefe fach may be eafily obferved by any one, who takes a brifk purge. 15. Where the ftimulus on the flomach, or on fome other part of the intefilnal canal, is fliil more permanent, not only the lacteal veffels, but the whole canal irfelf, becomes inverted from its ailbciations : this is the iliac pafiion, in which all the fluids mentioned above are thrown up by the mouth. At this time the valve in the colon, from the inverted motions of that bowel, and the inverted action of this living valve, does not prevent the regurgitation of its contents. The flructure of this valve may be reprefented by a flexile leathern pipe funding up from the bottom of a vefTei of water : its fides collapfe by the preflure of the ambient fluid, as a fmali part of that fluid paries through it j but if it has a living power, and by its inverted action keeps itfelf open, it becomes like a rigid pipe, and will admit the whole liquid to pafs. See Seel:. XXXIX. 2. 5. In this cafe the patient is averfe to drink, from the conftant inverfion of the motions of the flomach, and yet many quarts are daily ejected from the itomach, which at length fmell of ex- crement, and at lad feem to be only a thin mucilaginous or aque- ous liquor. From whence is it poflible, that this great quantity of fluid for many fuccefiive days can be fupplied, after the cells of the body have given up their fluids, but from the atmofphere r* When the cutaneous branch of abforbents acts with unnatural ftrength, it is probable the inteitinal branch has its motions inverted, and us a fluid is fupplied without entering the arterial fyftem. Could oiling or painting the fkin give a check to this difeafe ? So when the flomach has its motions inverted, the lymphatics of the flomach, which are moft ftrictly aflbciated with it, invert their motions at the fame time. But the more diftant branches lymphatics, which are lefs ftri£ljy affociated with it, aft with increafed energy •, as the cutaneous lymphatics in the cholera, or iliac panion, above defcribed. And other irritative motions be- come decreafed, as the pulfations of the arteries, from the extra- derivation or exhauflion of the fenforial power. Sometimes when ftronger vomiting takes place the more dif- - nt branches of the lymphatic fyftem invert their motions with thofe of the flomach, and loofe ftools are produced, and cold fweats. So when the lacteals have their motions inverted, as during the operation of flrong purges, the urinary and cutaneous ab- uts have their motions increafed to fupply the want of flu- . in the blood, as in great third ; but after a meal with fufS- cient Sect. XXV. 16. AND INTESTINES. 22 3 cient potation the urine is pale, that is, the urinary abforbents ad weakly, no fupply of water being wanted for the blood. And when the inteitinal abforbents act too violently, as when too great quantities of fluid have been drunk, the urinary abforb- ents invert their motions to carry off the fuperfiaity, which is a new circumftance of affociation, and a temporary diabetes fu- pervenes. 16. I have had the opportunity of feeing four patients in the iliac pamon, where the ejected material fmelled and looked like excrement. Two of thefe were fo exhaufted at the time I faw them, that more blood could not be taken from them, and as their pain had ceafed, and they continued to vomii up every- thing which they drank, I fufpected that a mortification of the bowel had already taken place, and as they were both women advanced in life, and a mortification is produced with iefs pre- ceding pain in old and weak people, thefe both died. The other two, who were both young men, had ftill pain and ftrength fufficient for further venefeclion, and they neither of them had any appearance of hernia, both recovered by repeated bleeding, and a fcruple of calomel given to one, and half a dram to the other, in very fmall pills : the ufual means of clyfters, and purges joined with opiates, had been in vain attempted. I have thought an ounce or two of crude mercury in Iefs violent difeaf- es of this kind has been of ufe, by contributing to reftore its natural motion to fome part of the inteftinal canal, either by its weight or ftimulus , and that hence the whole tube recovered its ufual affociations of progreffive periftaltic motion. I have in three cafes ken crude mercury given in fmall dofes, as one or two ounces twice a day, have great effect in flopping pertinacious vomitings. 17. Belides the affections above defcribed, the ftomach is lia- ble, like many other membranes of the body, to torpor without confequent inflammation : as happens to the membranes about the head in fome cafes of hemicrania, or in general head-ach. This torpor of the ftomach is attended- with indigeftion, and confequent flatulency, and with pain, which is ufually called the cramp cf the ftomach, and is relievabie by aromatics, effential oils, alcohol, or opium. The intrution of a gall-ftone into the common bile-duel: from the gall-bladder is fometimes miftaken for a pain of the ftomach, as neither of them is attended with fever ; but in the paffage of a gall-ftone, the pain is confined to a Iefs fpace, which is exact- ly where the common bile-duel enters the duodenum, as ex- plained in Section XXX. 3. Whereas in this gaftrodynia the pain is diffufed over the whole ftomach ; znd, like ether difeafes % fr 224 OF THE STOMACH Sect. XXV. 17, m from torpor, the pulfe is weaker, and the extremities colder, and the general debility greater, than in the p of a gill-done > • in the former the debility is the confequence of the pain, in the latter it is the caufe of it. Though the nrfl fits oi the gout, I believe, commence with a torpor of the liver ; and the ball of the toe becomes inflam< mftead of the membranes of the liver in confequence of this tor- por, as a coryza or catarrh frequently fucceeds a long expofure of the feet to cold, as in fnow, or on a moift brick-floor ; yet in old or exhaufted conftitutions, which have been long habituated to its attacks, it fometimes commences with a torpor of the ftom- ach, and is transferable to every membrane of the body. When the gout begins with torporsof the flomach, a painful fenfation of cold occurs, which the patient compares to ice, with weak pulfe, cold extremities, and ficknefs *, this in its (lighter degree is relievable by fpice, wine, or opium ; in its greater degree it is fucceeded by fudden death, which is owing to the fympathy of the ftomach with the heart, as explained below, If the flomach becomes inflamed in confequence of this gouty torpor of it, or in confequence of its fympathy with fome oth- er part, the danger is lefs. A frckfiefs and vomiting continues many days, or even weeks, the ftomach rej 3 ; every thing ftimulant, even opium or alcohol, together with much vifcid mucus *, till the*.inflammation at length ceafes, as happens when ether membranes, as thofe of the joints, are the feat oi gouty in- flammation ; as obferved in Seel:. XXIV. 2. 8. The fympathy, or aflbciation of motions, between thofe of the flomach and thofe of the heart, is evinced in many difeafes. Firft, many people areoccafionally affected with an intermiflion of their pulfe for a few days, which then ceafes again. In this ca there is a flop of the motion oi the heart, and at the fame time a tendency to eructation from the ftomach. As foon as the patic ■.Is a tendency to the intermiflion of the motion of his heart, if he voluntari:y brings up wind from his ftomach, the flop of the heart does not occur. From hence I elude that the (top of di- geftion is the primary difeafe *, and that air is inftantly generated •m the aliment, which begins to ferment, if the digeftivc pro- cefs is impeded for a moment, (fee SecJ. XXIII. 4.) •, and that the flop of the heart is in confequence of the aflbciation of the motions thefe vifcera-as explained in Sect- XXXV. 1. 4.5 but if the little air, which is inftantly gc cd during the temporary torpor of the flomach, be evacuated, the digeflion recommences, and tl temporary torpor of the heart does not follow. One patient, whom I lat and who had bten five or fix days much troubled iter million of a puliation of his heart, and who Sect. XXV. 17. AND INTESTINES. 225 who had hemicrania with fome fever, was immediately relieved from them ail by lofing ten ounces of blood, which had what is termed an inflammatory crult on it. Another inftance of this affociation between the motions of the ftomach and heart is evinced by the exhibition of an over dofe of foxglove, which induces an inceffant vomiting, which is attended with very ilow, and fometimes intermitting pulfe. — . "Which continues in fpite of the exhibition of wine and opium for two or three days. To the fame aflbciation muft be afcri- bed the weak pulie, which conftantly attends the exhibition of emetics during their operation. And alfo the fudden deaths, which have been occafioned in boxing by a blow on the ftom- ach ; and laflly, the fudden death of thofe, who have been long debilitated by the gout, from the torpor of the itomach. See Sea. XXV. i#4. I i Vol. I. F f SECT ■2z6 a Of GLANDS. Sect. XXVI. i. f. SECT. XXVI. OF THE CAPILLARY GLANDS AND MEMBRANES. 1. I. The capillary veffels are gland r. 2. Their excretory duels, Experiments on the mucus of the intejlines, abdomen , cellular mem- brane•, and on the humours of the eye. 3. Scurf on the head, coughy catarrh, diarrhoea > gonorrhoea,, 4. Rheumatifm. Gout. Lep~ rcfy. II. I. The mofl minute membranes are unorganized. 2. Larger membranes are compofed of the duels of the capillaries, and the mouths of the abforbents. 3. Mucilaginous fluid is fecreted en their furf aces. III. Three kinds of rheumatifm. 1. 1. The capillary vefTels are like all the other glands except t]\e abforbent fyftem, inafmuch as they receive blood from the arteries, feparate a fluid from it, and return the remainder by the veins. 2. This feries of glands is of the mod extenfive' ufe, as their excretory duels open on the whole external fldn forming its per- fpirative pores, and on the internal furfaces of every cavity of the body. Their fecretion on the fkin is termed inienfible per- fpiration, which in health is in part reabsorbed by the mouths cf the lymphatics, and in part evaporated in the air ; the fecre- tion on the membranes, which line the larger cavities of the body, which have external openings, as the mouth and inttilinal canal, is termed mucus, but is not however coagulable by heat ; and the fecretion on the membranes of thofe cavities of the body, which have no external openings, i3 called lymph or water, as in the cavities of the cellular membrane, and of the abdomen ; this lymph however is coagulable by the heat cf boiling water. Some mucus nearly as viicid as the white of egg, which was dis- charged by ftool, did not coagulate, though 1 evaporated it to one fourth of the quantity, nor did the aqueous and vitreous humours of a (hern's eye coagulate by the like experiment ; but the fe- rofitv from an anafarcous leg, and that from the abdomen of a I perfon, and the cry (taiiine humour of a fheep's eye, igulated in the fame heat. 3. When any of thcie capillary glands are Simulated into r.ter irritative actions, than is natural, they fecrete a more copious material ; and as the mouths of the abforbent fyftem, :ich open in their tv, are at the fame time Simulated in- to greater action, the : r and more faline part of the fecre- c lyid is taken up 1 ; and the remainder is not only more copious bi :'. x."- vifcid than natural. This is more or lets troublefom Sect. XXVI. i. 4, OF GLANDS. a*y troublefome or noxious according to the importance of the func- tions of the part affect eld : on the {kin and bronchia, where this fecretion ought naturally to evaporate, it becomes fo vifcid as to adhere to the membrane; on the tongue it forms a pellicle, which can with difficulty be fcraped off; produces the fcurf en the heads of many people ; and the mucus, which is fpit up by others in coughing. On the noftrils and fauces, when the fe- cretion of thefe capillary glands is increased, it is termed fimple catarrh ; when in the inteltines, a mucous diarrhoea ; and in the urethra, or vagina, it has the name of gonorrhoea, or fluor albus. A. When thefe capillary glands become inflamed, a {till more vifcid or even cretaceous humour is produced upon the furfaces of the membranes, which is the caufe or the effect of rheumat- ifm, gout, leprofy, and of hard tumours of the legs, which arc generally termed fcorbutlc ; all which will be trea ted of here- after. II. 1. The whole furface of the body, with all its cavities and contents, are covered with membrane. It lines every veffel, forms every cell, and binds together all the mufcular and per- haps the offeous fibres of the body ; and is itfelf therefore prob- ably a fimpler fubftance than thoie fibres. And as the contain- ing veffels of the body from the larger! to the leaft are thus lined and connected with membranes, it follows that thefe membranes themfeives confift of unorganized materials. For however fmall we may conceive the diameters of the minuted veffels of the body, which efcape our eyes and gb.ffes, yet thefe veffels mud confift of coats or fides, which are made up of an unorganized material, and which are probably produ- ced from a gluten, which hardens after its production, like the filk or web of caterpillars and fpiders. Of this material confift the membranes, which line the (hells of eggs, and the (hell itfelf, both which are unorganized, and are formed from mucus, which hardens after it is formed, either by the abforption of its more fluid part, or by its uniting with fome ,part of the atmofphere. Such is alfo the production of the fhells of fnails, and of fhell- fiih, and I fuppofe of the enamel of the teeth. 2. But though the membranes, that compofethe fides of the moft minute veffels, are in truth unorganized materials, yet the larger membranes, which are perceptible to the eye, feem to be compofed of an intertexture of the mouths of the abforbent fyf- tem, and of the excretory ducts of the capillaries, with their con- comitant arteries, veins, and nerves : and from this con flruct ion it is evident, that thefe membranes mult poffefs great irritability to peculiar hamuli, though they are incapable of any motions, ihat are viable to the naked eje ; and daily experience fhews us, tha£ 223 OF GLANDS. Sect. XXVI. 2. 3, that in their inflamed ftate they have the greateft fenfibility to pain, as in the pleurify and paronychia. 3. On all thefe membranes a mucilaginous or aqueous fluid is fecreted, which moiftens and lubricates their furfaces, as was explained in Section XXIII. 2. Some have doubted, whether this mucus is feparated from the blood by an appropriated fet of glands, or exudes through the membranes, or is an abrafion or cleftruclion of the furface of the membrane itfelf, which is con- tinually repaired on the other fide of it, but the great analogy between the capillary vefTeis, and the other glands, countenances the former opinion $ and evinces, that thefe capillaries are the glands, that fecrete it ; to which we muft add, that the blood in pafling thefe capillary vefTeis undergoes a change in its colour from florid to purple, and gives out a quantity of heat ; from whence, as in other glands, we muft conclude that fomething 5s fecreted from it. III. The feat of rheumatifm is in the membranes, or upon them *, but there are three very diftincl: difeafes, which com- monly are confounded under this name. Firft, when a mem- brane becomes afiTecled with torpor or inactivity of the vefTeis which compofe it, pain and coldnefs fucceed, as in the hemicra- jiia, and other head-achs, which are generally termed nervous jheumatifm ; they exift whether the part be at reft or in motion, and are generally attended with other marks of debility. Another rheumatjfm is faid to exift, when inflammation and fwelling, as well as pain, afrecT: fome of the membranes of the joints, as of the ancles, wrifts, knees, elbows, and fometimes of the ribs. This is accompanied with fever, is analogous to pleu- xify and other inflammations, and is termed the acute rheu- jnatifm. A third difeafe is called chronic rheumatifm, which is diftin- guiihed from that firft mentioned, as in this the pain only af- .tccts the patient during the motion of the part, and from the fecond kind of rheumatifm above defcribed, as it is not attend- ed with quick pulfe or inflammation. It is generally believed to fucceed the acute rheumatifm of the fame part, and that fomc coagulable lymph, or cretaceous, or calculous material, has been left on the membrane ; which gives pain, when the muf- cles move over it, as fome extraneous body would do, which was too infoluble to be abforbed. Hence there is an analogy be- tween this chronic rheumatifm and the difeafes which produce gravel or gout-ftones ; and it may perhaps receive relief from, the fame remedies, fuch as aerated fal foda. SECT. •StcT. XXVII. i. i. OF HEMORRHAGES. 2*9 SEC T. XXVID OF HEMORRHAGES. J. The veins are abforbent veffels. 1. Hemorrhages from inflam- mation. Cafe of hemorrhage from the kidney cured by cold bathing. Cafe of hemorrhage from the nofe cured by cold immerfion. II. Hemorrhage from venous parahfs. Of piles. Black foots. Petechia. Confumptim* Scurvy of the lungs. Black nefs oj the face and eyes in epileptic f is. Cure of hemorrhages from venous inability. I. As the imbibing mouths cf the abforbent fyftem already clcfcribed open on the furface, and into the larger cavities of the body, fo there is another fyftem of abforbent veiTeis, which are not commonly elteemed fuch, I mean the veins, which take up t£ie blood from the various glands and capillaries, after their prop- er fluids or fecretions have been Separated from it. The veins refemble the other abforbent veflels ; as the progres- sion of their contents is carried on in the fame manner in both, they alike abforb their appropriated fluids, and have valves to prevent its regurgitation by the accidents of mechanical vio- lence. This appears fir ft, becaufe there is no pulfation in the \ery beginnings of the veins, as is (cen by nvicrofcopes 5 which mult happen, if the blood was carried into them by the actions of the arteries. For though the concurrence of various venous ftreams of blood from different diftances mutt prevent any pul- fation in the larger branches, yet in the very beginnings of all thei'e branches a pulfation mult unavoidably exift, if the circula- tion in them was owing to the intermitted force of the arteries* Secondly, the venous abforption of blood from the penis, and from the teats of female animals after their erection, is (till more (milarto the lymphatic abforption, as it is previoufly poured in- to cells, where all arterial impulfe mud ceafe. There is an experiment, which feems to evince this venou^s abforption, which confifts in the external application of a ftim lus to the lips, as of vinegar, by which they become inftantly pale ; that is, the bibulous mouths of the veins by this tumulus are excited to abforb the blood fatter, than it can be fupplicd by the ufual arterial exertion. See Sect. XXIII. 5. 1. There are two kinds of haemorrhages frequent in 'difeafes, one is where the glandular or capillary action is too powerfully ex- erted, and propels the blood forwards more baddy, than the veins £an abforb it •, and tlie other is, where the abforbent power of the w. OF HEMORRHAGES. Sect. XXVII. r. u is is diminifhed, or a branch of them is become totally paralytic. The former cf thefe cafes is known by the heat of the part, and the general fever or inflammation that accompanies the haem- orrhage. A haemorrhage from the nofe or from the lungs is ibmetime:; a crifis of inflammatory difeafes, as of the hepatitis and gout, and generally ceafes fpontaneoufly, when the veflels are confideiably emptied. Sometimes the hemorrhage recurs daily periods accompanying the hot fits of fever, and ceafing in the cold fils, or in the intermiffions ; this is to be cured by re- moving the febnle paroxyfms, which will be treated of in their place. Otherwife it is cured by vene feci: ion, by the internal or external preparations of lead, or by the application of cold, with an nMtemious diet, and diluting liquids, like other inflammations. t Which by inducing a quiefcence en thofe glandular parts, that are affected, prevents a greater quantity of blood from being protruded forwards, than the veins are capable of abforbing. ?>lr. B had a hcemorrhage from his kidney, and parted with not lefs than a pint of blood a dzy (by conjecture) along with his urine for above a fortnight : venefections, mucilages, • Ifams, preparations of lead, the bark, alum, and dragon's blood, iates, with a large bliller on his loins, were feparately tried, in large dofes, to no purpofe. He was then directed to bathe in a cold fpring up to the middle of his body only, the upper part bc- ~ covered, and the hemorrhage diminifhed at the firft, and ceafed at the fecond immerfion. In this cafe the external capillaries were rendered quiefcent by the coldnefs of the water, and thence a lefs quantity of blood was circulated through them ; and the internal capillaries, or other glands, became quiefcent from their irritative aflbciations with the external ones ; and the haemorrhage was flopped a fuf- ficient time for the ruptured vefTels to contract their apertures, or for the blood in thofe apertures to coagulate. Mrs. K had a continued haemorrhage from her nofe for fome days ; the ruptured vefTel was not to be reached by plugs up the noftrils, and the feniibility of her fauces was fuch that nothing could be borne behind the uvula. After repeated vene- fection, and other common applications, (he was directed to im- merfc her whole head into a pad of water, which was made cold- er by the addition of feveral handfuls of fait, and the haemorrhage immediately ceafed, and returned no more ; but her pulfe con- tinued hard, and (lie v/as ncccfiitated to lofe blood from the arm the fucceeding day. Query, might not the cold bath inftantly flop haemorrhages the lungs in inflammatory cafes : — for the {hortnefs of breath Sect. XXVII. 2. 1. OF HAEMORRHAGES. 231 breath of thofe, who go fuddenly into cold water, is not owing to the accumulation of blood in the lungs, but to the quiefcence of the pulmonary capillaries from aflbciation, asr explained in Sec- tion XXXII. 3. 2. II. The other kind of haemorrhage is known from its being at- tended with a weak pulfe, and other fymptoms of general debil- ity, and very frequently occurs in thofe, who have difeafed levers, owing to intemperance in the ufe of fermented liquors. The conftitutions are fhewn to be liable to paralyfis of the lymphatic abforbents, producing the various kinds of dropfies in Section XXIX. 5. Now if any branch of the venous iyftem lofes its power of abforption, the part fwelis, and at length b'urfts and discharges the blood, which the capillaries or other glands circu- late through them. It fometimes happens that the large external veins of the legs burft, and effufe their blood ; but this occurs moil frequently in the veins of the interlines, as the vena portarum is liable to fuf- fer from a fchirrus of the liver oppofmg the progrefiion of the blood, which is abforbed from the interlines. Hence the" piles are a fymptom of hepatic obilruc~tion, and hence the copious dis- charges downwards or upwards of a black material, which has been called melancholia, or black bile ; but is no other than the blood, which is probably difcharged from the veins of the intef- tines. J. F. Meckel, in his Experiments deFinibusVaforum^publifhec! at Berlin, 1772, mentions his difcovery of a communication of a lymphatic vefTel with the gaftric branch of the vena portarum. It is poflible, that when the motion of the lymphatic becomes retrograde in fome difeafes, blood may obtain a paflage into it* where it anaftomofes with the vein, and thus be poured into the interlines. A difcharge of blood with the urine fometimes at- tends diabetes, and may have its fource in the fame manners Mr. A , who had been a hard drinker, and had the gutta rofacea on his face and bread, after a ftroke of the palfy . voided near a quart of a black vifcid material by ftool : on diluting it with water it did not become yellow, as it muft have done it had been infpiffated bile^ but continued black like the grounds of coffee. But any other part of the venous fyftem may become quiefcent or totally paralytic as well as the veins of the interlines : all which occur more frequently in thofe who have difeafed livers, than in any others. Hence troublefome bleedings of the nofe, or from the lungs with a weak pulfe ; hence haemorrhages from the kidneys, too great menftruation ; and hence the oozing of blood from every part of the body, and the petechia in thofe fevers, which are 232 OF HAEMORRHAGES. Sect. XXVll. 2. t* are termed putrid, and which iserroneoufiy afcribed to the thin- fs of the blood : for the blood in inflammatory difeafes is equal- ly fluid before it coagulates" in the cold air. Is not that hereditary confumption, which occurs chiefly in darkeyed people about the age of twenty, and commencJM with flight pulmonary hemorrhages without fever, a difeafe or this kind ? — Thefe haemorrhages frequently begin during fleep, when the irritability or the lungs is not fuflicienc in thefe patients to carry on the circulation without the atti fiance of volition j for in our waking hours, the rrfotions of the lungs are in part volun- tary, efpecially if any difficulty of breathing renders the efforts of volition neceffary. See Oafs I. 2. r. 3. and Clafs III. 2. 1- 12. Another fpecies of pulmonary confumption which feems more certainly of lcrofulous origin is described in the next Sec- tion, No. 2. I have feen two* cafes of women, cf about forty years of age* both of whom were feized with quick weak pulfe, with difficult refpiration, and who fpit up by coughing much vifcid mucus mixed with dark coloured blood. They had both large vibices on their limbs, and petechia? ; in one the feet were in danger of mortification, in the other the legs were ©edematous. To relieve the difficult refpiration, about fix ounces of blood were taken from one of them, which to my furprife was fizy, like inflamed blood : they had both palpitations or unequal pulfations of the heart. 1 They continued four or five weeks with pale and bloat- ed countenances, and did not ceafe fpitting phlegm mixed with black blood, and the pulfe feldom flower than 130 or 135 in a minute. This blood, from its dark colour, and from the many vibices and petechia-:, feems to have been venous blood ; the quicknefs of the pulfe, and the irregularity of the motion of the heart, are to be afcribed to debility of that part of the fyftem ; us the extravafation of blood originated from the defect of ven- ous abforption. The approximation of thefe two cafes to fea- fcurvy is peculiar, and may allow them to be called fcorbutus pulmonalis. Had thefe been younger fubjects, and the paraly- fis of the veins had only affecled the lungs, it is probable the difeafe would have been a pulmonary confumption. Lafl week I faw a gentleman of Birmingham, who had for ten days laboured under great palpitation of his heart, which was fo diflinctly felt ky the hand, as to difcountenance the idea of there being a fluid in the pericardium. He frequently fpit up mucus (tained with dark coloured blood, his pulfe very un- j equal and very weak, with cold hands and nofe. He could not jie down at all, and for about ten days paft could not fleep a min- ute together, but waked perpetually with great uneafmefs. Could Sect. XXVII. 2. i. OF HAEMORRHAGES. n% Could thofe fymptoms be owing to very extenfive adhefions of the lungs ? or is this a fcoibutus pulmonalis ? After a few days he fuddenly got ib much better as to be able to fleep many hours at a time by the ufe of one grain of powder of foxglove twice a day, and a grain of opium at night. After a few clays longer, the ~krk was exhibited, and the opium continued with fome wine ; 'and the palpitations of his heart became much relieved, and hb recovered his ufual degree of health, but died fuddenly fome months afterwards. In epileptic fits the patients frequentlybecome blackin theface, from the temporary paralyfis of the venous fyftem of this part. I have known two inftances where the blacknefs has continued many days. M. P- , who had drank intemperately, was feized with the epilepfy when he was in his fortieth year ; in one of thefe fits the white part of his eyes was left totally black' with efFufed blood ; which was attended with no pain or heat, and was in a few weeks gradually abforbed, changing colour as is ufual with vibices from bruifes. The haemorrhages produced from the Inability of the veins to abforb the refluent blood, are cured by opium, the preparations of fteel, lead, the bark, vitriolic acid, and blifters ; but thefe have the effecT: with much more certainty, if a venefe&ion to a few- ounces, and a moderate cathartic with four or fix grains of cal- omel be premifed, where the patient is not already too much de- bilitated ; as one great means of promoting the abforptipn of any fluid confifts in previoufly emptying the veflels, which are t • receive it, Vol. I. Gc SECT- 234 PARALYSIS OF Sect. XXVIIL i SECT. XXVIIL OF THE PARALYSIS OF THE ABSORBENT SYSTEIvI. 1. Taralyfis of the lacleals^ atrophy. Dijlafte to animal food. If, Caufe of dropfy. Caufe of herpes. Scrofula. Mefenteric con-> fumption. Pulmonary confumption. Why ulcers in the lungs are fo difficult to heal. The term paralyfis has generally been ufed toexprefs the lofs of voluntary motion, as in the hemiplegia, but may with equal propriety be applied to exprefs the difobediency of the mufcu- lar fibres to the other kinds of ftimulus ; as to thofe of irritation or fenfation. *, I. There is a fpecies of atrophy, which has not been well un- derftood •, when the abforbent veflels of the ftomach and intef- tines have been long inured to the ftimulus of too much f(nrit- uous liquor, they at length, either by the too fudden omiflion of fermented or fpirituous potation, or from the gradual decay of nature, become in a certain degree paralytic ; now it is obferv- ed in the larger mufcles of the body, when one fide is paralytic, the other is more frequently in motion, owing to the lefs expen- diture of fenforial power in the paralytic limbs ; fo in this cafe the other part of the abforbent fyftem acts with greater force, or with greater perfeverance, in confequence of the paralyfis of the lacteals ; and the body becomes greatly emaciated in a fmail time. I have feen feveral patients in this difeafe, of which the fol- lowing are the circumitances. i. They were men about fifty rears of age, and had lived freely in refpccl: to fermented liquors. 2. They loft their appetite to animal food. 3. They became- fuddenly emaciated to a great degree. 4. Their fkins were dry and rough. 5. They coughed and expectorated with difficulty a vifcid phlegm. 6. The membrane of the tongue was dry and red, ami liable to become ulcerous. The inability to digeft animal food, and the confequent dif- taf*e to it, generally precede the dropfy, and other difeates, which origin-ate From fpirituous potation. I fuppofe when the ftomach becomes inirritable, that there is at the lame time a de- ficiency oi gaftric acid ; hence milk feldom agree. . thefc patients, urflefs it be preVi curdled, as they have not fuffi* it gaftric acid to curdle it ; and hence, v >le food, which is itfelf acefcent, will agree with their ftomachs longer than an- , hith requires more 6f the :ic acid for it5 digeiiion. In Sect. XXVIII. 2. ABSORBENTS. 235 In this difeafe the Cfcin is dry from the increafed abforption of the cutaneous lymphatics, the fat is abforbed from the increafed abforption of the cellular lymphatics, the mucus of the lungs is too vifcid to be eafily fpit up by the increafed abforption of the thinner parts of it, the membrana fneideriana becomes dry, covered with hardened mucus, and at length becomes inflamed and full ofapthse, and either thefe (loughs, or pulmonary ulcers, terminate the fcene. II. The immediate caufe of dropfy is the paralyfis of fome other branches of the ahforbent iyltem, which are called lym- phatics, and which open into the larger cavities of the body, or into the cells of the cellular membrane ; whence thofe cavities or cells become diftended with the fluid, which is hourly fecre^ ted into them for the purpofe of lubricating their furfaces. As . is more fully explained in No. 5. of the next Section. As thofe lymphatic vefTels confift generally of a long neck or mouth, which drinks up its appropriated fluid, and of a conglob- ate gland, in which this fluid undergoes fome change, it hap- pens, that fometimes the mouth of the lymphatic, and fometimes the belly or glandular part of it, becomes totally or partially par- alytic. In the former cafe, where the mouths of the cutaneous lymphatics become torpid or quiefcent, the fluid fecreted on the fkin ceafes to be abforbed, and erodes the fkin by its faline acrL? mony, and produces eruptions termed herpes, the difcharge from which is as fait, as the tears, which are fecreted too faft to be reab- sorbed, as in grief, or when the puncta lacrymalia are obftrucled, and which running down the cheek redden and inflame the fkin. When the mouths of the lymphatics, which open on the mu- cous membrane of the noitrils, become torpid, as on walking into the air in a frofty morning j the mucus, which continues to be fe- creted, has not its aqueous and faline part reabforbed which run- ning over the upper lip inflames it, and has a fait tafte, if it fails on the tongue. When the belly, or glandular part of one of thefe lymphatics^ becomes torpid, the fluid abforbed by ifs mouth ftagnates, and forms a tumour in the gland. This difeafe is called the fcrofula. If thefe glands fuppurate externally, they gradually heal, as thofe of the neck •, if they fuppurate without an opening on the ex- ternal habit, as the mefenteric glands, a hectic fever enfues, which deilroys the patient ; if they fuppurate in the lungs, a pulmonary confumption enfues, which is believed thus to differ from that defcribed in the preceding Section, in refpect to its feat or prox- imate caufe. It is remarkable, that matter produced by fuppuration will lie concealed in the body many weeks, or even months, without pro* iluciu 235 PARALYSIS OF Sect. XXVIII. 2, ducing hectic fever ; but as foon as the wound is opened, fo as to admit air to the furface of the ulcer, a hectic fever fupervenes, even in very few hours, which I formerly conceived to be owing to the azotic part of the atmofphere rather than to the oxygene ; becaufe thofe medicines, which contain much oxygene, as the calces or oxydes of metals, externally, applied, greatly contribute to heal ulcers; of thefe are the folutions of lead, and mercury, and copper in acids, or their precipitates ; but have fince believed it to be owing to the oxygene. See Clafs II. 1. 6. 7. in Vol. II. of this wor] . Hence when wounds are to be healed by the fird intention, as it ir> called, it is neceflary carefully to exclude the air from them. Hence we have one caufe, which prevents pulmonary ul- cers from healing, which is their being perpetually expofed to the air. Another caufe of the difficulty of healing pulmonary ulcers may arife from the inactivity of the veflels of the air-cells, which are covered with a membrane differing both from that of the mu- cous membranes of other cavities of the body, and from the ex- ternal fkin. For it is probable, that the air-cells alone of the lungs conflitute the organ of refpiration, and not the internal fur- faces of the branching vefTels of the trachea which lead to the air-cells. And from a vegetable analogy mentioned below they probably exhale or perfpire either nothing or much lefs than the furfaces of the pulmonary vefTels, which lead »to them. Hence the mucus, which in common coughs or fuperficial peripneumo- ny is fecreted on the fnrface of the branching vefTels of the lungs, is forced up in coughing by the air behind it, which is haitily ex- cluded from the air-cells, and flowlv inhaled into them. But if there was any mucus or matter formed in thefe air-cells, it is not cafy to underftand how it could be brought up by coughing, as; no air could get admittance behind it ; which may be one caufe of the difficulty of healing pulmonary ulcers if they exifl on the furface of the air-cells ; but not fo, if they exift in the vefTels: leading to the air-cells, as after a wound with a lword, or when a vomica has burft after a peripneumony. In the vegetable fyflem, I think, there can be no doubt, but that the upper furface of the leaves conftitutes the organ of res- piration, and M. Bonnet in his Ufage des Feuilles mows by 3 curious experiment, that the upper furfaces of leaves do not ex- hale half lb much as their under furfaces. He placed the ftalks of many leaves frefh collected into glafs-tubes filled with water, of many of thefe the upper furfaces were fmeared with oil, and ihe under furfaces of many others of them ; and he uniformly found Sect. XXVIII. 2. ABSORBENTS. 237 found by the finking of the water in the tube1?, that the upper Surfaces exhaled lefs by half than the under Surfaces. Both the dark-eyed patients, which are affected with pulmo- nary ulcers from deficient venous abforption, as defcribed in Sec- : XXVII. 2. and the light-eyed patients from deficient lym-? ptiatic abforption, which we are now treating of, have generally large apertures of the iris 5 thefe large pupils of the eyes are a common mark of want of irritability ; and it generally happens, that an increafe of fenfibility, that is, of motions in confequence of fenfation, attends thefe coriftitutions. See Sect. XXXI. 2. "Whence inflammations may occur in thefe from ftagnated fluids re frequently than in thofe conftitutions, which polTefs more irritability and lefs fenfibility. Great expectations in refpe£t, to the cure cf confumptions, as well as of many other difeafes, are produced by the very in- genious exertions of Dr. Beddoes ; who has eftablifhed an ap- paratus for breathing various mixtures of airs or gafles, at the hot- wells near Briftol, which well deferves the attention of the public. Dr. Beddoes very ingeniously concludes, from the florid col- our of the blood of Confumptive patients, that it abounds in ox- ygene 5 and that the rednefs of their tongues, and lips, and the fine blufh of their cheeks, fhew the prefence of the fame prin- ciple, like flefh reddened by nitre. And adds, that the circum- ftance of the confumptions of pregnant women being flopped in their progrefs during pregnancy, at which time their blood may be fuppofed to be in part deprived of its oxygene, by ox- ygenating the blood of the foetus, is a forcible argument in fa-? vour of this theory ; which muft foon be confirmed or con- futed by his experiments. See EfTay on Scurvy, Confumption, &c. by Dr. Beddoes. Murray. London. Alio Letter to Dr, parwin by the fame. Murray. London. SECT. ?38 RETROGRADE Sect. XXIX. i. u SECT. XXIX. ON THE RETROGRADE MOTIONS OF THE ABSORBENT SYSTEM* I. Account of the abforbent fyjlem. II. The valves of the abforbent veffels ;r;. v fuffer their funis to regurgitate in fome difeafes. III. C: * io7i from the alimentary canal to the bladder by means of the abforbent vejftis. IV. The phenomena of diabetes explained. V. I. The pi. wa cf drcpfies explained. 2. Cafes of the tife * cf foxglove. VI. Of cold five at s. VII. Tranfations of matter , of chyle , of milk , cf urine > operation of purging drugs applied ex- ttma'/y. VIII. Circumjlances by ivhich the fluids, that are ef- fufed by the retrograde motions of the abforbent veffels, are diflin- tjhed. IX. Retrograde motions of vegetable juices. X. Ob- jections anjkuered. XI. The caufes, ivhich induce the retrograde motions of animal vejfels, and the medicines by ivhich the natural motions are reflored. N. B. The following Section is a tr (inflation oj apart of a Latin the- fis ivritten by the late Mr. Charles Darwin, ivhich ivas printed ivith his pyrze-differtation on a criterion between matter and mu- cus in 1 7 oo. Sold by Cadell, London. I. Ac con tit cfthe Ahforbent Syflem. f i. The abforbent fyPcem of vefTels in animal bodies confifts of feveral branches, differing in refpect. to their fituations, and to the fluids, which they abforb. The inte'tinal abforbents open their mouths on the internal furfaces of the intefiines j their office is to drink up the chyle and che other fluids from the alimentary canal ; and they are termed lacteals, to diflinguiih them from the other abforbent vef- fels, which hive been termed lymphatics. Thofe, whofe mouths are difperfed on the external fkin, im- bibe a great quantity of water from the atmofphere, and a part of the perfpirable matter, which does not evaporate, and are termed cutaneous abforbents. Thofe, which arife from the internal furface of the bronchia, an i which imbibe moiflure from the atmofphere, and a part of the bronchial mucus, are called pulmonary abforbents. Thofe, which open their innumerable mouths into the cells of tie cellular membrane ; and whofe ufe is to take up the fluidi which is poured into thofe cells, after it has done its of- . ; may be called cellular abforbents. Thofe, which arife from the internal furfaces of the mem- branes, Sect. XXIX i. 2. ABSORBENTS. < 239 branes, which line the larger cavities of the body, as the thorax, abdomen, fcrotum, pericardium, take up the mucus poured in- to thofe cavities ; and are diftinguiihed by the names of their re- fpective cavities. Whilft thofe, which arife from the internal fmfaces of the urinary bladder, gall-bladder, falivary duels, or other receptacles of fecreted fluids,vmay take their names from thofe .fluids ; the thinner parts of which it is their office to abforh : as urinary, bilious, or falivary abforbents. 2. Many of thefe abforbent veiTeis, both lacteals and lymphat- ics, like fome of the veins, are replete with valves : which feem defigned to aflift the progrefs of their fluids, or at lead to pre- vent their regurgitation ; where they are fubjeeted to the inter- mitted preflure of the mufcular, or arterial actions in their neighbourhood. Thefe valves do not however appear to be necefTary to all the abforbents, any more than to all the veins ; fmce they are not found to exift in the abforbent fyftem of fifh ; according to the difcoveries of the ingenious, and much lamented Mr. Hewfon, Philof. Tranf. v. 50., Enquiries into the Lymph. Syft. p. 94. 3. Thefe abforbent vefiels are alfo fur mined with glands, which are called conglobate glands ; whefe ufe is not at prefent fufficiently inveftigated ; but it is probable that they referable the conglomerate glands both in ftructnre and in ufe, except that their abforbent mouths are for the conveniency of fituation placed at a greater diflance from the body of the gland. The con- glomerate glands open their mouths immediately into the fan- guiferous veffels, which bring the blood, from whence they ab- forb their refpectiye fluids, quite up to -the gland -7 but thefe conglobate glands collect their adapted fluids from very diftant membranes, or cyfts, by means of mouths furnifhed with long necks for this purpofe j and which are called lacteals, or lym- phatics. \ 4. The fluids, thus collected from various parts of the body, pafs by means of the thoracic du. 2. The mouths of the lymphatics feem to admit water to pafs through them after death, the inverted way, eafier than the nat- ural one ; fince an inverted bladder readily lets out the water with which it is filled ; whence it miybe inferred, that there is no obftach at th« mouths of thefe veflels to prevent the regurgi- tation of their I Sect. XXIX. 2. 3. ABSORBENTS, 241 I was induced to repeat this experiment* and having accurate- ly tied the ureters and neck of a freih o^:'s bladder, I made an opening at the fundus of it ; and then, having turned it infide outwards, filled it half full with water, and was furprifed to fee it empty itfelf fo haftily. I thought the experiment more ap- pofite to my purpofe by fufpending the bladder with its neck downwards, as the lymphatics are chiefly fpread upon this part of it, as fhewn by Dr. Watfon, Philof. Tranf. v. 59. p. -392. 3. In fome difeafes, as in the diabetes, and fcrofula, it is prob- able the valves themfelves are difeafed, and are thence incapable of preventing the return of the fluids they fhould fupport. Thus the valves of the aorta itfelf have frequently been found fcirrhous, according to the difiecTions of Monf. Lieutaud, and have given rife to an interrupted pulfe, and laborious palpitations, by fufFer- ing a return of part of the blood into the1 heart. Nor are any parts of the body {0 liable to fcivrhofity as the lymphatic glands and vefTels, infomuch that their fcirrhofities have acquired a dif- tincT name, and been termed fcrofula. 4. There are valves in other parts of the body, analogous to thofe of the abforbent fyftem, and which are liable, when difeaf- ed, fo regurgitate their contents : thus the upper and lower orifi- ces of the ftomach are clofed by valves, which, when too great quantities of warm water have been drunk with a defign to pro- mote vomiting, have fometimes refilled the utmofl efforts of the abdominal mufcles, and diaphragm : yet, at other times, the up- per valve, or cardia, eafdy permits the evacuation of the contents of the ftomach *, whilft the inferior valve, or pylorus, permits the ; bile, and other contents of the duodenum, to regurgitate into the ftomach. 5. The valve of the colon is well adapted to prevent the re~ trograde motion of the excrements •, yet, as this valve is poflefT- ed of a living power, in the iliac paiiion, either from fpafm, or other unnatural exertions, it keeps itfelf open, and either fufTers or promotes the retrograde movements of the contents of the interlines below ; as in ruminating animals the mouth of the firfl ftomach feems to be fo eonftruCted, as to facilitate or aiLit the regurgitation of the food ; the rings of the cefophagus after- wards contracting themfelves in inverted order. De Hacn, by means of a fvringe, forced fo much water into the recVum intei- tinum of a dog, that he vomited it in a fall dream from Ins mouth 5 and in the iliac paffion above mentioned, excrements and clyfter are often evacuated by the mouth, See Section XXV. 15. 6. The puncla lacrymalia, with the laerymal fack and nafal duel, compote a complete gland, and much refemble the in) v r°L- li H tina! 242 RETROGRADE Sect. XXIX. 2. tinal canal : the pun£ta lacrymalia are abforbent mouths, that take up the tears from the eye, when they have done their of- fice there, and convey them into the noftrils ; but when the naf- al duel is obftructed, and the lacrymal fack diftended with its- fluid, on prefiiire with the finger the mouths of this gland (pun da lacrymalia) will readily difgorge the fluid, they had pre- vioully ablorbed, back into the eye. 7. As the capillary vefTels receive blood from the arteries, and fepanratlng the mucus, or perfpirable matter from it, convey the remainder back by the veins ; thefe capillary vefTels are a fee of glands, in every refpecr, fimilar to the decretory vefTels of the liver, or other large congeries of glands. The beginnings of thefe capillary vefTels have frequent anaflomofts into each other, in winch circumftance they are refembled by the lacleals ; and like the mouths or beginnings of other glands, they area fet of abforbent vefTels, which drink iyp the blood which is brought to them by the arteries, as the chyle is drunk up by the lacteals : for the circulation of the blood through the capillaries is proved to be independent of arterial impulfe ; fincc in the blufh of fhamc, and in partial inflammations, their aclion is increafed, without any increafe of the motion of the heart. 8. Yet not only the mouths, or beginnings of thefe anaftomo- fing capillaries are frequently feen by microfcopes, to regurgitate fome particles of blood, during the ftruggles of the animal; but retrograde motion of the blood, in the veins of thofe animals, from the very heart to the extremity of the limbs, is obfervable, by intervals, during the diftrefTes of the dying creature. Haller,- Elem. Pbyfiol. t. i. p. 216. Now, as the veins have perhaps all of them a valve fomewhere between their extremities and the heart, here is ocular clem onftration of the fluids in thisdifeaf- ed condition of the animal, repairing through venous valves: and it is hence highly probable, from the Itricled analogy, that if the courfe of the fluids, in the lymphatic veflels, could be fub- jedted to microfcopic observation, they would alio, in the difeaf- ed Mate of the animal, be feen* to repafs the valves, and the mouths of thofe veflels, which had previoufly abforbed them, or promoted their progrefTion. Mr. Cooper relates fome curious inftances of difcafed valves of the abforbent fyftem, and found on difle&ing dogs, who had died fome hours after he had put a ligature on the receptaculum chyli, that in the cellular membrane of thofe dogs which had their ftomachs full previous to the application of the ligature, much chyle was effufed on many of the vifcera, and into the cellular membrane connecting the laminae of the mefentery, and on the anterior furfacefl of the pancreas, and of the kidneys ; part Sect. XXIX. 3. 1. ABSORBENTS. 243 part of which might have efcaped from a rupture of the recep- taculum chyli ; yet other parts of this general etfufion of chyle muff feem to have been occafioned by their retrograde a£tiou in the dving ftate of the animals. MedicaJ Researches? p. 106. There is a curious cafe of ifchuria related by Dr. J. Semer in the Tranfaclions of the College of Philadelphia, Vol. f. 1 793, which continued more than three years, during which time, if the urine was not drawn off by a catheter, it was frequently void- ed by vomiting, and fometimes by the iliin ; which could not be accounted for, as Dr. Senter juftly obferves, but by fuppo- iing the exiftence of the retrograde action of fome pares of the lymphatic fyftem. ,111. Communication from the Alimentary Canal to the Bladder ', by means of the Abforbent Vefeh. Many medical philofophers,both ancient and modern, have fuf- •pecked that there was a nearer communication between the ftom- ach and the urinary bladder, than that of the circulation : they were led into this opinion from the great expedition with which cold water, when drunk to excefs, pafles off by the bladder ; and from the fimilarity of the urine, when produced in this hafty ,• manner, with the material that was drunk. The former of thefe circumftances happens perpetually to thofe who drink abundance of cold water, when they are much heated by exercife, and to many at the beginning of intoxication. Of the latter, many inftances are recorded by Etmuller, t. xi. p. 716. where limple water, wine, and wine with fugar, and emulfions, were returned by urine unchanged. There are other experiments, that feem to demonftrate the -exiftence of another pafTage to the bladder, befides that through the kidneys. Thus Dr. Kratzenftein put ligatures on the ure- ters of a dog, and then emptied the bladder by a catheter ; yet in a little time the dog drank greedily, and made a quantity of water, (Difputat. Morbor. Halleri. t. iv. p. 63.) A fimilar ex- periment is related in the Philofophical Tranfactions, with the fame event, (No. 6$, 67, for the year 1670.) Add to this, that in fome morbid cafes the urine lias continu- ed to pafs, after the fuppuration or total deftruttion of the kid- neys ; of which many inftances are referred to in the Elem. Phyfiol. t. vii. p. 379. of Dr. Haller, From all which it muft be concluded, that fome fluids have parTed from the ftomach or abdomen, without having gone through the fanguiferous circulation : and as the bladder is fup- plied with many lymphatics, as defcribed by Dr. Watfon, in the Philoi 244 RETROGRADE Sect. XXIX. 3. */ Phrlof. Tranf. v. 59. p. 392. and as no ether vefiels open intoit be - fides thefe' and the ureters, it feems evident, that the unnatural urn;;, produced as above defcribed,when the ureters were tied, or the kidneys obliterated, was carried into the bladder by the retro- grade motions of the urinary branch of the lymphatic fyflem. Tire more certainlyto a/certain theexiftenceof another commu- nication between the ftomachand bladder, befidesthatof the circu- lation,thefoilowingexperiment was made, to which I mult beg your nt attention : — A friend of mine (June 14, 1772) orMrink- ing repeatedly of cold ftnafl punch, till he began to be intoxica- ted, made a quantity of colourlek urine. He then drank about two drams of nitre diflolved in fome of the punch, and ate about twenty (talks of boiled afparagus : on continuing to drink more of ihf punch, the next urine that he made was quite clear, and without fmeil ; but in a little time another quantity was made, which was net quite fc colourlefs, and had a ltrong fmell of the paragus : he then loft about four ounces of blood from the arm. The fmell of afparagus was not at all perceptible in the bloodv rteither when freih taken, not the next morning, as myfelf and two others accurately attended to ; yet this fmell Was ftrongly perceived in the urine, which was made juft before the blood was taken from his arm. Some bibulous paper, moiftened in the ferum of this blood, and fuffered to dry, fhewed no figrts of nitre by its manner of burning. But fome of the fame paper, moiftened in the urine, and drievl, on being ignited, evidently fhewed the prefence of ni- tre. This Mood and the urine flood fome days expofed to the fun in the open air, till they were evaporated to about a fourth of their original quantity, and began to ftink : the paper, which was then moiftened with the concentrated urine, (hewed the pref- ence of much nitre by its manner of burning •, whilft that moif- tened with the blood fhewed no fuch appearance at all. Hence it appears, that certain fluids at the beginning of in- toxication, find another paiTage to the bladder befides the long courfe of the arterial circulation \ and as the inteftinal abforb- ents are joined with the urinary lymphatics by frequent anafto- mcfes, as Hewfon has demonitrated ; and as there is no other road, we may juftly conclude, that thefe fluids pafs into the blad- der by the urinary branch of the lymphatics, which has its mo- tions inverted durin^ the difeafed ftate of the animal. A gentleman, who had been fome weeks affected with jaun- dice, and whofe urine was in coniequence of a very deep yellow, took fome cold fmall punch, in which was dilTolved about a dram of nitre •, he then took repeated draughts of the punch, and k*pt himfelf in a ccol room, till on the approach of flight intoxication Stcf.XXIX. 4. .1. ABSORBENTS. 24 2 jjtotoxication he made a large quantity of water ; this water had il*ht yellow tinge, as might be expected from a fmall admix- ture of bile fecreted from the kidneys ; but if the v. had palled through the fanguiferous veffels, which were now re- plete with bile (his whole (kin being as yellow as gold) would not this urine alfo, as well as that he had made for weeks before, have been of a deep yellow ? Paper dipped in this water, and dried, and ignited, mewed evident marks of the prefence of ni- tre, when the flame was blown out. IV. The Phenomena of the Diabetes explained, and of fame Diar- rhoeas. The phenomena of many difeafes are only explicable from the retrograde motions of fome of the branches of the lymphat- ic fyitem ; as the great and immediate How of pale urine in the .beginning of drunkennefs ; in hyfteric paroxyfms ; from being expofed to cold air 5 or to the influence of fear or anxiety. Before we endeavour to illuitrate this doctrine, by defcribing the phenomena of thefe difeafes, we mud premife one circum- ftance ; that all the branches of the lymphatic fyftem have a cer- tain fympathy with each other, infomuch that when one branch is (timuiated into unufual kinds or quantities of motion, fome other branch has its motions either increafed, or decreafed, or inverted at the fame time. This kind of fympathy can only be proved by the concurrent teftimOpy of numerous facts, which will be related in the courfe of the work. I (hall only add here, that it is probable, that this fympathy does not depend on any communication of nervous filaments, but on habit ; owing to the various branches of this fyftem having frequently been Itim- ulated into action at the fame time. There are athoufand initancesoimvoluntarvmotions aiTociated in this manner ; as in the act of vomiting, while the motions of the {tomach and cefophagus are inverted, the pulfations of the arterial fyftem by a certain fympathy become weaker ; and when the bowels or kidneys are ftimulatedby poifon, a (lone, or inflammation, into more violent action ; the flcmach and cefoph- agus by fympathy invert their motions. 1. When any one drinks a moderate quantity of vinous fpir- it, the whole fyftem acts with more energy by confent with the .ftomach and interlines, as is feen from the glow on the flcin, and the mcreafe of ftrength and activity ; but when a greater quan- tity of this inebriating material is drunk, at die fame time that thQ lacteals are excited into greater action to abibrb it ; it fre- quently happens, that die urinary branch of abfoibents, which is connected 246 RETROGRADE Sect. XXIX. 4. z„ connected with the la£leals by many anaftomofes, inverts its mo- tions, and a great quantity of pale unanimalized urine is drt charged. » By this wife contrivance too much of an unnecefTary fluid is prevented from entering the circulation — This may be called the drunken diabetes, to diilinguifh it from the other tem- porary diabetes, which occur in hyileric diieafes, and from con- tinued fear or anxiety. 2. If this idle ingurgitation of too much vinous fpirit be dai- ly pracHfed, the urinary branch of abforbents at length gains a habit of inverting its motions, whenever the lacleals are much ftimulated ; and the whole or a great part of the chyle is thus daily carried to the bladder without entering the circulation, and the body becomes emaciated. This is one kind of chronic dia- betes, and may be diftinguifhed from the others by the tafle and appearance of the urine ; which is fweet, and of the colour of whey, and may be termed the chyliferous diabetes. 3. Many children have a iimilar deposition of chyle in their urine, from the irritation of worms in their interlines, which {Simulating the mouths of the lacteals into unnatural action, the urinary branch of the abforbents becomes inverted, and carries part of the chyle to the bladder : part of the chyle alfo has been carried to the iliac and lumbar glands, of which inftances are recorded by Haller, t. vii. 225. and which can be explained on no other theory : but the directions of the lymphatic fyflem of the human body, which have yet been publiihed, are not fufli- ciently extenfive for our purpofe ; yet if we may reafon from comparative anatomy, this tranflation of chyle to the bladder is much illuftrated by the account given of this fyftem of vefiels in a turtle, by Mr. lijwfon, who obferved, "That the lacteals near the root of the meientery anaftomofe, fo as to fo' m a net-work, from which feveral large branches go into fome confiderable lymphatics lying near the fpine ; and which can be traced al- moll to the anus, and particularly to the kidneys. Philof- Tranf. v. ^9. p. 199 — Enquiries, p. 74. 4. At the fame time that the urinary branch of abforbents, in the beginning of diabetes, is excited into inverted action, the ceikilar branch is excited by the fympathy above mentioned, in- to more energetic action ; and the fat, that was before depofited, is reabforbed and thrown into the blood veiTeis •, where it floats, miflaken for chyle, till the late experiments of the inge- nious Mr. Hewfon demonftrated it to be fat. This appearance of what was miflaken for chyle in the blood, which was drawn from thefe patients, and the obftructed liver, 1 very frequently accomp \ this difeafe, feems to have j Dr. Mead to fufpeel the diabetes was owing to a defect of fanguification \ Sect. XXIX. 4. f. ABSORBENTS. 247 fanguification ; and that the fcirrhohty of the liver was the orig- inal caufe of it : but as the fcirrhus of the liver is moil frequent- ly owing to the fame caufes, that produce the diabetes and drop- fies *, namely, the great ufe of fermented liquors ; there is no wonder they mould exift together, without being the confe- quence of each other. 5. If the cutaneous branch of abforbents gains a habit of being excited into ftronger action, and imbibes greater quantities of moifture from the atmofphere, at the fame time that the urina- rv branch has its motions inverted, another kind of diabetes is formed, which may be termed the aqueous diabetes. Iri this diabetes the cutaneous abforbents frequently imbibe an amazing quantity of atmofpheric moifture ; infomuch that there are au- thentic hiftories, where many gallons a day, for many weeks to-, gether, above the quantity that has been drunk, have been dis- charged by urine. Dr. Keil, in his Medicina Statica, found that he gained eigh- teen ounces from the moid air of one night ; and Dr. Percival affirms, that one of his hands imbibed, after being well chafed, near an ounce and half of water, in a quarter of an hour. (Tranfaft. of the College, London, vol. ii. p. 102.) Home's Medic. Fa£ts, p. 2. feci:. 3. Dr. Rollo in his work on Diabetes has (hewn, that one patient, whom he weighed after being ten minutes in the warm bath, did not weigh heavier on his leaving it. Dr. Currie, I think, mentions a fimilar facl. I fufpec~t, that if the bath be made very- hot, perhaps much above animal heat, the bather may perfpire more than he abibrbs, and become in reality lighter. And that in a more moderate heat, if the patient has been previouilv ex- haufted by abftinence or fatigue, that he will abforb much ; but that if his fyftem be already full of fluids, from the food and flu- ids, which he has previoufly eaten and drunk, he may not abforb anything. See Clafs I. 3. 2. 6. The pale urine in hyfterical women, or which is produced by fear or anxiety, is a temporary complaint of this kind ; and it would in reality be the fame difeafe, if it v/as confirmed by habit. 6. The purging (tools, and pale urine, occafioned by expofing the naked body to cold air, or fprinkling it with cold water, orig- inate from a fimilar caufe ; for the mouths of the cutaneous lymphatics being fuddenly expofed to cold become torpid, and ceafe, or nearly ceafe, to acl: ; whilft, by the fympathy above de- scribed, not only the lymphatics of the bladder and fnteftines ceafe alfo to abforb the more aqueous and faline part cf the flu- ids fecreted into them ; but it is probable that thefe lymphatics invert their motions, and return the fluids, which were previ- oufl *48 ftETROGRADE Sect. XXIX. 4. 7, ouflv abforbed, into the inteflines and bladder. At the very in flan t that the body is eipofed naked to thz cold air, an unu- fual movement is felt in the bowels -, as is experienced by boys going into the cold bath '; this could not occur from an obftruc- tion of the perfpirable matter, fmce there is not time for that to be returned to the bowels by the courfe of the circulation. There is alfo a chronic aqueous diarrhoea, in which the atmos- pheric moifture, drunk up by the cutaneous and pulmonary lym- phatics, is poured into the interlines, by the retrograde motions of the lacteals. This difeafe is mod fimilar to the aqueous di- abetes, and is frequently exchanged for it : a diltinct inftance of this is recorded by Benningerus, Cent. v. Obf. 98. in which an aqueous diarrhoea fucceeded an aqueous diabetes, and deftroy- ed the patient. There is a curious example of this, defcribed by Sympfon (De Re Medica)-— u A young man (fays he) was feiz- ed with a fever, upon which a diarrhoea came on, with great fhipor ; and he refufed to drink any thing, though he was parched up with excemve heat : the better to fupply him with moifture, I directed his feet to be immerfed in cold water ; immediately 1 obferved a wonderful decreafe of water in the vef- fel, and then an impetuous dream of a fluid, fcarcely coloured, was difcharged by {tool, like a cacaract." 7. There is another kind of diarrhoea, which lias been called cceliaca ; in this difeafe the chyle, drunk up by the lacteals of the fmall interlines, is probably-poured into the large interlines, by the retrograde motions of their lacteals : as in the chyliferous diabetes, the chyle is poured into the bladder, by the retrograde motions of the urinarv branch of abforbents. The chyliferous diabetes, like this chyliferous diarrhoea, pro- duces fudden atrophy ; fince the nourishment, which ought to fupply the hourly waile of the body, is expelled by the bladder, or reilum : whilfl the aqueous diabetes, and the aqueous diar- rhoea produce exceffive thirlt ; becaufe the moifture, which is obtained from the atmofphere, is not conveyed to the thoracic receptacle, as it ought to be, but to the bladder, or lower intes- tines •, whence the chyle, blood, and whole fyftem of glands, are robbed of their proportion of humidity. 8. There is a third fpecies of diabetes, in which the urine is mucilaginous, and appears ropy in pouring it from one vefTel into another •, and will fometimes coagulate over the fire. This difeafe appears by intervals, and ceafes again, and feems to be occafioned by a previous dropfy in fome part of the body. When fuch a collection is reabforbed, it is not always returned into the circulation ; but the fame irritation that ftimulates one lymphatic branch to reabforb the depofited fluid, inverts the urinarv Sect. XXIX. 4. o. ABSORBENTS. ift * Urinary branch, and pours it into the bladder. Hence tins mu- cilaginous diabetes is a cure, or the confequence of a cure, of a worfe difeafe, rather than a difeafe itfelf. Dr. Cotunnius gave half an ounce of cream of tartar, every morning, to a patient, who had the anafarca \ and he voided a great quantity of urine *, a part of which, put over the fire, co- agulated, on the evaporation of half of it, to as' to look like the white of an egg. De Ifchiade Nervos. This kind of diabetes frequently precedes a dropfy; and has this remarkable circumftance attending it, that it generally hap- pens in the night \ as during the recumbent (late of the body, the fluid, that was accumulated in the cellular membrane, or in the lungs, is more readily abforbed, as it is lefs impeded by its gravity. I have feen more than one inftance of this difeafe. Mr. D. a man in the decline of life, who had long; ace u domed himfelf to fpirituous liquor, had fvvelled legs, and ether fymp- toms of approaching anafarca : about once in a week or ten days, for feveral months, he was feized, on going to bed, with great general uneafinefs, which his attendants refembled to an hyiteric lit ; and which terminated in a great difcharge of vifcid urine ; his legs became lefs fvvelled, and he continued in better health for feme days afterwards. I had not the opportunity to try it this urine would coagulate over the fire, when part of it was evaporated, which I imagine would be the criterion of this kind of diabetes 5 as the mucilaginous fluid depofited in the' ceils and cyfts of the body, which have no communication with the exter- nal air, feejms to acquire, by ftagnation, this property of coagula- tion by heat, which the fecreted mucus of the interlines and bla ■!■• der do not appear to pofTefs ; as I have found by experiment : and if any one (hould fuppofe this coagulable urine was fepa- rated from the blood by the kidneys, lie may recoiled, thai in the rnoft inflammatory difeafes, in which the blood is mod replete pr mod ready to part with the coagulable lymph, none of this appears in the urine. 9. Different kinds of diabetes require different methods of cure. For the fir ft kind, or chyliferous diabetes, after clearing the flomach and interlines, by ipecacuanha and rhubarb, to evacuate any acid material, which may too powerfully ftimuiate the mouths of the lacteals, repeated and large dofes of tincture of cantharides have been much recommended. The fpeeitic ftimulus of this medicine, on the neck of the bladder, is likely to excite the numerous abforbent veCcls, which are fpread cii that part, into ftronger natural actions, and by that means pre- vent their retrograde ones ; till, by perfitting in the ufe of the medicine, their natural habit: of motions might again be eftab- Vol. I. li Hfhed, 25° RETROGRADE Sect. XXIX. 4. 9, lifhed. Another indication of cure, requires fuch medicines, as by lining the inteftines with mucilaginous fubfiances, or with fuch as confiit of fmcoth particles, or which chemically deitroy the acri- mony of their contents, may prevent the too great aclion of the inteflinal abibrbents. For this purpofe, I have found the earth precipitated from a folution of alum, by means of fixed alcali, given in the dofe of half a dram every fix hews, of great advantage, v. ith a few grains of rhubarb, fo as to produce a daily evacuation* The food mould confifl; of materials that have the lead ftim- ulus, with calcareous water, as of Briftol and Matlock ; that the mouths of the la£teals may be as little ilimulated as is necerfary for their proper abforption \ left with their greater exertions, ihould be connected by fympathy, the inverted motions of the urinary lymphatics. The fame method may be employed with equal advantage in the aqueous diabetes, fo great is the fympathy between the ikus and the ftomach. To which, however, tome application to the fldn might be ufefully added ; as rubbing the patient all over with oil, to prevent the too great aclion of the cutaneous abforb- ents. I knew an experiment of this kind made upon one pa- tient with apparent advantage. The mucilaginous diabetes will require the fame treatment, which is moft efTicacious in the dropfy, and will be defcribed be- low. I mud add, that the diet and medicines above mentioned, are ftrcngiy recommended by various authors, as by Morgan, j Willis, Harris, and Etmuller ; but more hiflories of the fucceisful treatment of thefe difeafes are wanting to fully afcertain the moll efficacious methods of cure. In a letter from Mr. Charles Darwin, dated April 24, 1778, Edinburgh, is the fubfequent paiTage : — " A man who had long laboured under a diabetes died yeiterday in the clinical ward. He had for fome time drunk four, and palled twelve pounds of fluid daily : each pound of urine contained an ounce of fugar. He took, without eonfiderable relief, gum kino, fanguis draconis melted with alum, tincture of cantharide , '..inglafs, gum arabic, crab's eyes, Spirit of hartfhorn, and eat ten or fifteen oyfters thrice a day. Dr. Home, having read my theiis, bled Lim, and ud that neither the frefli blood nor t\\Q ferum tailed [w^^t. was opened this morning — every vifcus appeared in a found and natural ft ate, except that the left kidney had a very fmall pelvis, and that there was a confiderable enlargement of mod of the mefenteric lymphatic glands. I intend to infert this in my thefis, as it coincides with the experiment, where fc jragus was eaten at the beginning of intoxication, and its fmcll perceived in the urine, though not in the blood." The Sect. XXIX. 4. 9. ABSORBENTS. 25 1 The following cafe of chylifcrous diabetes is extracted from fome letters of Mr. Hughes, to whofe unremitted care the in- firmary at Stafford for many years was much indebted. Dated October 10, 1778. Richard Davis, aged 33, a whitefmith by trade, had drunk hard by intervals ; was much troubled with fweating of his hands, which incommoded him in his occupation, but which ceafed on his frequently clipping them in lime. About feven months ago he began to make large quantities of water ; his legs are cedem- at vis, his belly tenfe, and he complains of a rifing in his throat, like the globus hyftericus : he eats twice as much as other peo- ple, drinks about fourteen pints of fmall beer a day, befides a ' pint of ale, fome milk-porridge, and a bafon -of broth, ami he -makes about eighteen pints of water a day. He tried alum, dragon's blood, {ted, blue vitriol, and eanthar- ides in large quantities, and duly repeated, under the care of Dr. Underhill, but without any effect *, except that on the day after he omitted the <:anrharides, he made but twelve pints of water, but on the next day this gcod effect ceafed again. November 21. — He made eighteen pints of water, and he .now, at Drv Darwin's requeft, took a grain of opium every four hours, and five grains of aloes at night ; and had a flannel ihirfc given him. 22. — Made fixteen pints. 23. — Thirteen pints: drinks lefs. 24. — Increafed the opium to a grain and quarter every four hours : he made twelve pints. 25. — Increafed the opium to a grain and half: he now makes ten pints •, and drinks eight pints in a day. The opium was gradually increafed during the next fortnight^ till he took three grains every four hours, but without any fur- ther dimunition of his water. During the ufe of the opium he fweat much in the nights, fo as to have large drops ftand on his face and all over him. The quantity of opium was then grad- ually decreafed, but not totally omitted, as he continued to take about a grain morning and evening. January 17. — He makes fourteen pints of water a dav. Dr. Underhill now directed him two fcruplesof common refm tritu- rated with as much fugar, every fix hours ; and three grains of opium every night. 19. — Makes fifteen pints of water : fweats at night. 21. — Makes feventeen pints of water ; has twitchings of his limbs in a morning, and pains of his legs : he now takes a dram of refm for a dofe, and continues the opium. 23. — Water more coloured, and reduced to fzxteen pints, and h.e thinks has a hrackifh lade. 2-5. — Wa?. . , a RETROGRADE Sect. XXIX. 4. 9, 26. — Water reduced to fourteen pints. 28. — Water thirteen pints : he continues the opium, and takes four fcruples of the refm for a dofe. February 1. — Water twelve pints. 4. — Water eleven pints : twitchings lefs ; takes five fcruplc for a dofe. 8. — Water ten pints : has had many ftools. 12. — Appetite lefs, : purges very much. After this the refm either purged him, or would not ftay ori his ftomach •, and he gradually relapied nearly to his forA condition, and in a few months funk under the difeafe. October ?t, Mr. Hughes evaporated two quarts of the water, and obtained from it four ounces and half of a hard and brittle faccharine mafs,' like treacle which had been fomc time boiled. Pour ounces of blood, which he took from his arm with defign to examine it, had the common appearances, except that the fe- rum refembled cheefe-whey ; and that on the evidence of four perfons, two of whom did not know what it was they tailed, thf fe rum had a falttflj tnjle. From hence it appears, that the faccharine matter, with which the urine of thefe patients fo much abounds, does not enter the blood-veilels like the nitre and afparagus mentioned above ; but that the procefs of digeftiori refembles the proceft of the ger- minajjon of vegetables, or of making barley into malt ; as the vaft quantity of fugar found in the urine muffc be made from the food which he took (which was double that taken by others)^ land from the fourteen pints of frriall beer which he drank. And, fecondly, as the ferum of the blood was net fv/eet, the chyle ap- pears to have been conveyed to the bladder without entering the circulation of the blood, lince fo large a quantity of fugar, as was found in the urine, namely, twenty ounces a day, could not have previouily exiiled in the blood without being perceptible to the tafte. November 1. Mr. Hughes diiTolved two drams of nitre in a pint of a decoclionof the roots of afparagus, and added to it two ounces of tincture of rhubarb : the patient took a fourth part of this mixture every five minutes, till he had taken the whole. — In about half an hour he made eighteen ounces of water, which was very manifeftly tinged with the rhubarb j the fmelj of afparagus was doubtful. He then loft four ounces of blood, the ferum of which war, not fo opaque as that drawn before, but of a yellowifh call, as the ferum of the blood ufuaily appears. Paper, dipped three or four times in the tinged urine and dri- ed again, did not fcintillate when it was fct on fire ; but when the oect. XXIX. 5. 1. ABSORBENTS. G|| Che flame was blown out, the fire ran along the paper for half at* inch ; which, when the fame paper was ummpregnated, it- would not do ; nor when the fame paper was dipped in urine made before he took the nitre, and dried in the fame manner. Paper, dipped in the ferum of the blood and dried in the fame manner as in the urine, did not fcintillate when the flame was blown out, but burnt exactly in the fame maimer as the fame paper dipped in the ferum of blood drawn from another peribn. This experiment, which is copied from a letter of Mr. Hughes, as well as the former, fecms to evince the existence of another paffage from the midlines to the bladder, in this difeafe, befides that of the fanimlferous fvftem ; and coincides with the curious .experiment related in fection the third, except that the fmell of ' the afparagus was not here perceived, owing perhaps to the roots having been made ufe of inftead of the heads. The riling in the throat of this patient, and the twitchings of his limbs, feem to indicate fome fimilarity between the diabetes and the hyfteric difeafe, befides the great flow of pale urine, which is common to them both. Perhaps if the rnefenteric glands were nicely uifpe£ted in the chficclions of thefe patients ; and if the thoracic duct, and the Jarger branches of the lacteals, and if the lymphatics, -which ariie from the bladder, were well examined by injection, or by the knife, the caufe of diabetes might be more certainly under- stood. The opium alone, and the opium with the refin, feem much to have ferved this patient, and might probably have effected a cure, if the difeafe had been (lighter, or the medicine had been exhibited, before it had been confirmed by habit during the fev~ en months it had continued. The increafe of the quantity of water on beginning the large dofes of refin was probably owing to his omitting the morning dofes of opium. As the urine in chyliferous diabetes abounds fo much with faccharinc matter, as appears from the above cafe of Davis, Dr. Rollo has ingeniouily recommended a diet of animal food alone ; {his, with a diminution of the quantity of fluid, which the pa- tient was previouijy accuftomed to, is laid to have changed the quality of the urine, and to have diminilhed its quantity. See 3?art II. Clafs I. 3. 2. 6. of this worfc. V, The Phenomena of Qsopjies explained, 1. Some inebriates have their paroxyfms of inebriety termin- ated by much pale urine, or profufe fweats, or vomiting, or (tools ; £54 RETROGRADE Sect. XXIX. 5. u ilools ; others have their paroxyfms terminated by ftupor, or fleep, without the above evacuations. The former kind of the fe inebriates have been obfcrved to be inore liable to diabetes and dropfy •, and the latter to gout, gravel, and leprofy. Evoe ! attend ye bacchanalians ! ftirt at this dark train of evils, and amid yourimmodelc jells, and idiot laughter, recollect, Quern 'Dens vult perdere, priu: detnent'at. In rhofc who are fubject to diabetes and dropfy, the absorbent veficls are naturally more irritable than in the Litter ; and by be- ing frequently difturbed or inverted by violent ftimulus, and bj their too great fympathy with each other, they become at length either entirely paralytic, or are only fufceptible of motion from ?'->€. ftimulus of very acrid materials 5 as every part of the body, after having been ufed to great irritations, becomes lefs affected fey fin .-.Her ones. Thus we cannot diftinguifh objects in the night, for fome time after we come out of a ftrong light, though the iris is prefently diluted ; and the air of a fummer evening appears cold, after we have been expofed to the heat of the day. There are no cells in the body, where dropfy may not be pro- duced, if the lymphatics ceafe to abforb that mucilaginous fluid, which is perpetually depoiited in them, for thepurpofe of lubri- cating their furfaces. If the lymphatic branch, which opens into the cellular mem- brane, either does its office imperfectly, or not all ; thefe cells become replete with a mucilaginous fluid, which, after it has ftagnated feme time in the cells, will coagulate over the fire ; and is erroneoylly called water. Wherever the feat of this dif- cafc is, (unlefs in the lungs or other pendent vifcera) the mucilag- inous liquid above mentioned will fubfide to the molt depend- in 2 parts of the body, as the feet and legs, when thofe are lower than the head and trunk 5 for all thefe cells have communica- - ach other. When the cellular abferbents are become infenfible to their ufual irritations, it in oil frequently happens, but not always, that the cutaneous branch of abforbents, which is ftrictly aiToci- atcd wirh them, f after 3 the like inability. And then, as no wa- r is abforbed from the atmosphere, the urine is not only lefc diluted at the time of its fecretion, and confequently in lefs lantity and higher coloured : but great thirft is at the fame time induced, for as no water is abforbed from the atmofphcre • -ire the chyle and blood, the lacleals and other abforbent • s, which ha\L not loft their powers, are excited into more • • or m re . it action, to (iipply this deficiency \ whence Sect. 1XIX. 5. 1. ABSORBENTS. f#* ■> whence the urine becomes ftill lefs in quantity, and of a deeper' colour, and turbid like the yolk of an egg, owing to a greater ab- sorption of its thinner parts. From this ftronger action- of thole abforbents, which iiill retain their irritability, the fat is alio ab- sorbed, and the whole body becomes emaciated. This increafed exertion of fome branches of the lymphatics, while others are totally or partially paralytic, is refembled by what confcantly oc- curs in the hemiplegia 5 when the patient has loft the ufe of the limbs on one fide, he is mcefTantly moving thofe of the other -, for the moving power, not having accefs to the paralytic limbs^ becomes redundant in thofe which are not difeafed. The paucity of urine and third cannot be explained from a greater quantity of mucilaginous fluid being depofited in the cellular membrane : for though thefe fymptoms have continued many weeks, or even months, this collection frequently does not amount to more than very few pints. Hence alio the dif- ficulty of promoting copious fweats in anafarca is accounted for, as well as the great thirft, paucity of urine, and lofs of fat ; fmce, when the cutaneous branch of abforbents is paralytic, or nearly fo, there is already too fmall a quantity of aqueous fluid in the blood : nor can thefe torpid cutaneous lymphatics be readily ex- cited into retrograde motions. Hence likewife we underftand, why in the afcites, and fome other dropfies, there is often no thirft, and no paucity of urine 5 in thefe cafes the cutaneous abforbents continue to do their office. Some have believed, that dropfies were occafioned by the in- ability of the kidneys, from having only obferved the paucity of urine ; and have thence laboured much to obtain diuretic medi- cines *, but it is daily obfervable, that thofe who die of a total in- ability to make water, do not become dropfical in confequence of it : Fernelius mentions one, who laboured under a perfect fup- preflion of urine during twenty days before his death, and yet had no fymptoms of dropfy. Pathol. 1. vi. c. 8. From the fame idea many phyficians have reftrained their patients from drinking, though their third has been very urgent ; and fome cafes have been published, where this cruel regimen has been thought advantageous : but others of nicer obfervation are of opinion, that it has always aggravated the diftreiTes of the patient ^ and though it has abated his lwellings, yet by inducing a fever it has haftened his difTolution. See Traafa&ions of the College, London, vol. ii. p. 235. Cafes of Dropfy by Dr. G. Baker. The cure of anafarca, fo far as refpecis the evacuation of the accumulated fluid, coincides with the idea of the retrograde ac- tion of the lymphatic fyftem. It is well known that vomits, and other drugs, which induce ficknefs or naufea, at the fame time that -6 RETROGRADE .Sect. XXIX. £ * A J that they evacuate the llomach, produce a great abfofptlon of the lymph accumulated in the cellular membrane. In the op- eration of a vomit, net only the motions of the (lomach a-nd du- odenum become inverted, but alio thofe of the lymphatics and iacteais, which belong to them ; whence a great quantity of chyle and lymph is perpetually poured into the (lomach and in- terlines, during the operation, and evacuated by t^ie mouth. Now at the fame time, other branches of the lymphatic fyitem, viz. thofe which open on thecellulai membrane, are brought in- td more energetic action, by the fympathy above mentioned, and an increafe of their abforption is produced. Hence repeated vomits, and cupreous ialts, and fmall dofes of fquill or foxglove, are fo efficacious in this difeafe. And as draf- tic purges act alfo by inverting the motions of the la;£teals •, and • thence the other branches of lymphatics are induced into more powerful natural action, by fympathy, and drink up the fluids from all the cells of the body -, and by their anaitomofes, pour them into the lacteal branches ; which, by their inverted actions, return them into the intcitines ; and they are thus evacua- ted from the body : — thefe purges alio are ufed with fuccefs in difcharging the accumulated fluid in auaiarca. II. The following cafes are related with defieu to afcertain the particular kinds of dropfy in which the digitalis purpurea, or common foxglove, is preferable to fquill,- or other evacuants, and were firit published in 1780, in a pamphlet entitled Exper- iments on mucilaginous and purulent Matter, &*c. Cadell. Lon- don. Other cafes of dropfy, treated with digitalis, were after » wards publifhed by Dr. Darwin in the Medical TrunfacUons, vol. iii. in which there is a miftake in refpect to the dok of the powder of foxglove, which ihould have been from five grains to one, initead of from five grains to ten. Anafana of the Lungs. 1. A lady, between forty and fifty vcar:, of age, had orer. i - difpofed fome time, was then feized with cough and lever, and afterwards expectorated much digefted mucus. This expecto- ration fuddenly ceafed, and a considerable difficulty of breathing fupervened, with a pulfe very irregular both in velocity and flrength •, (lie was much dilheiTed at firft lying down, and firft rifing ; but after a minute or two bore either of thofe attitud with eafc. She had no pain or numbnefsin her arms ; me had ho hectic fever, nor any cold fhiverings, and the urine was due quantity, and of the natural colour. The difficulty of breathing was twice confiderably relieved by :t. XXIX. 5. 2. ABSORBENTS. 257 fmall dofes of ipecacuanha, which operated upwards and down- wards, but recurred in a few days : (he was then directed a de- cocYion of foxglove, (digitalis purpurea) prepared by boiling four ounces of the frefh leaves from two pints of water to one pint ; to which were added two ounces of vinous fpirit : (he took three large fpoonfuls of this mixture every two hours, till the. had taken it four times *, a continued ficknefs fupervened, with fre- quent vomiting, and a copious flow of urine s thefe evacuations continued at intervals for two or three days, and relieved the difficulty of breathing.- — She had fome relapfes afterwards, which were again relieved by the repetition of the decoction of foxglove. 2. A gentleman, about fixty years of age, who had been ad- dicted to an immoderate ufe of fermented liquors, and had been very corpulent, gradually loft his ftrength and flefh, had great difficulty of breathing, with legs fomewhat fvvelled, and a very- irregular pulfe. He was very much diftreffed at firft lying down, and at firft riling from his bed, yet in a minute or two was eafy in both thefe attitudes. He made ftraw-coloured urine in due quantity, and had no pain or numbnefsof his arms. He took a large fpoonful of the decoction of foxglove, as above, every hour, for ten or twelve fucceffive hours, had inceliant fick- nefs for about two days, and palled a large quantity of urine ; upon which his breath became quite eafy, and the fwelling of his legs fubfided \ but as his whole conftitution was already fink- ing from the previous intemperance of his life, he did not fur- vive more than three or four months. Hydrops Pericardii. 3. A gentleman of temperate life and fedulous application bufmefs, between thirty and forty years of age, had long beea fubjett, at intervals, to an irregular pulie : a few months ago he became weak, with difficulty of breathing, and dry cough. In this fituation a phyfician of eminence directed him to abftain from all animal food and fermented liquor, during which regimen all his complaints increafed ; he now became e ited, and total- ly loft his appetite \ his pulfe very irregular both in velocity and ftrength \ with great difficulty of breathing, and {oiv.e fv\ of his legs 5 yet he eordd lie down horizontally in his bed, thou he got little lleep, and palled a due quantity of urine, and of : natural colour : no fullnefs or hardnefs could be perceived about; the region of the liver \ and he had no pain or numbnefs in his arms. One night he had a mod profufe fvveat all over his body and limbs, which quite deluged his bed, and for a day or two fome- Voi... I. & K what I ■ . ■ 25$ RETROGRADE Sect. XXIX. ?. what relieved his difficulty of breathing, and his pulfe became' lets irregular : this copious fweat recurred three or four times at the intervals of five or fix days, and repeatedly alleviated his iyrn ptoms. He was directed one large fpoonful of the above decoction of foxglove every hour, till it procured fome confiderable evacua- tion : after he had taken it eleven fucceffive hours he had a few liquid (tools, attended with a great flow of urine, which laft had a dark tinge, as if mixed with a few drops of blood : he continued fick at intervals for two days, but his breath became quite eaiy, and his pulfe quite regular, the fwelling of his leg* difappeared, and his appetite and fleep returned. He then took three grains of white vitriol twice a day, witlr fome bitter medicines, and a grain of opium with five grains of rhubarb every night ; was advifed to cat flefh meat, and fpice, as his ftomach would bear it, with fmall beer, and a few glaffes of wine j and had ifiues made in his thighs ; and has fuffered no relapfe. 4. A lady, about fifty years of age, had for fome weeks great difficulty of breathing, with very irregular pulfe, and confidera- ble general debility : fhe could lie down in bed, and the urine was in due quantity and of the natural colour, and fhe had no pain or numbnefs of her arm*. She took one large fpoonful of the above deco£lion of foxglove every hour, for ten or twelve fucceffive hours •, was fick, and made a quantity of pale urine for about two days, and was quite relieved both of the difficulty of breathing, and the irregularity of her pulfe. She then took a' grain of opium, and five grains of rhubarb, every night, for many weeks ; with fome flight cha- lybeate and bitter medicines, and has fuffered no relapfe. Hydrops Thoracis. 5. A tradefman, about fifty years of age, became weak an J fhort of breath, efpecially on increafe of motion, with pain in une arm, about the mfertion of the biceps mufcle. He obferv- ed he femetimes In the night made an umifual quantity of pale water. He took calomel, alum, and peruvian bark, and all his mptoms increafed : his legs began to fwell confiderably \ his breath became more difficult, and he-could not lie down in bed; •but all this time he made a due quantity of itraw-colouved yrater. The decoction of foxglove was given as in the preceding ca- fes, which operated chiefly by purging, and feemed to relieve his breath for a day or two ; but alio feemed to contribute to weaken Sect. XXIX. 5. 2. ABSORBENTS. ^9 weaken him.— He became after fome weeks univerfally drbpfica?, and died comatofe. 6. A young lady of delicate conftitution, with light eyes and hair, and who .had perhaps lived too abftemioufly both in relpetl: •to the quantity and quality of what (he ate and drank, was fell- ed with great difficulty of breathing, fo as to threaten immedi- ate death. Her extremities were quite cold, and her breath fek -cold to the back of one\s hand. She had no fweat, nor could Jie down for a fmgle moment ; and had previouily, and at prev- ent, complained of great weaknefs and pain and numbnefs of both her arms ; had no f welling of her legs, no thirft, water in due quantity and colour. Her filler, about a year before, was r-affli&ed with fimilar fymptoms, was repeatedly blooded, and di - ■ed univerfally dropfical. A grain of opium was given immediately, and repeated every ■fix hours with evident and amazing advantage ; afterwards a. Jblifter, with chalybeates, bitters, and effential oils, were exhibit- ed, out nothing had fuch eminent effect in relieving the difficul- ty of breathing and coldnefs of her extremities as opium, by the ufe of which in a few weeks (lie perfectly regained her Jxealtb, and has fuffered no relapfe. Afckes. 7. A young lady of delicate conftitution having been expo- fed to great fear, cold, and fatigue, by the overturn of a chaife •in the night, began with pain and tumour in the right hypo- chondrium : in a few months a fluctuation was felt throughout ihe whole abdomen, more diftinctly perceptible indeed about the region of the ftomach ; fince the integuments of the lower part of the abdomen generally become thickened in this difeafe by a degree of anafarca. Her legs were not fwelied, no third, water in due quantity and colour. — She took the foxglove fo as to in- duce ficknefs and ftools, but without abating the f welling, and was obliged at length to fubmit to the operation of tapping. 8. A man about fixty-feven, who had long been accuftomed to fpirituous potation, had fome time laboured under afcites 5 his legs fomewhat fwelied ; his breath eafy in all attitudes ; no appetite ; great thirft ; urine in exceedingly fmall quantity, very deep coloured, and turbid ; pulfe equal. He took the foxglove in fuch quantity as vomited him, and induced ficknefs for two days ; but procured no flow of urine, or diminution of his fwell- ing ; but was thought to leave him confiderably weaker. 9. A corpulent man, accuftomed to a large potation of fer- mented liauors, had vehement cough, difficult breathing, ana- farca o RETROGRADE Sect. XXIX. 5. 2. farca of his legs, thighs, and hands, and confiderable tumor-iy with evident fluctuation of his abdomen ; his pulfe was eq his urine in fmall quantity, of deep colour, and turbid. Th fuellings had been twice confiderably abated by draftic cathar- tics. He took thiee ounces of a decoction of foxglove (ma by boiling one ounce of the freih leaves in a pint of water) every three hours, for two whole days ; it then began to vomit and purge him violently, and promoted a great flow of urine ; he was by thefe evacuations completely emptied in twelve hours. After two or three month:, all thefe fymptoms returned, and were again relieved by the ufe of the foxglove ; and thus in the fpace of about three years he was about ten times evacuated, and continued all that time his ufual potations : excepting at firft, the medicine operated only by urine, and did not appear confiderably to weaken him. — The lad time he took it, it had iio effect ; and a few weeks afterwards he vomited a great quail* tity of blood, and expired, QJJERIES. 1. As the firft: fix of thefe patients had a due difchargc of urine, and of the natural colour, was not the feat of the difeafe confined to fome part of the thorax, and the fwelling of the legs rather a fymptom of the obstructed circulation of the blood, than of a paralyfis of the cellular lymphatics of thofe parts ? 2. When the original difeafe is a general anafarca, do not the cutaneous lymphatic^ always become paralytic at the fame time with the cellular ones, by their greater fympathy with each oth- er ? and hence the paucity of urine, and the great thirif, diftin- guifh this kind of dropfy ? 3. In the anafarca of the lungs, when the difeafe is not very great, though the patients have confiderable difficulty of breath- ing at their firft lying down, yet after a minute or two their breath becomes cafy again -, and the fame occurs at their firfl rifing. Is not this owing to the time neceflary for the fluid in the cells of the lungs to change its place, fo as the leaft; to incom- mode refpiration in the new attitude ? 4. In the dropfy of the pericardium does not the patient bear the horizontal 01 pw npendicular attitude with equal cafe ? Does this circumftance diftmguiih the dropfy of the pericardium from t of the lungs and of the thorax ? 5. Do the univerfal fweats diftinguim the dropfy of the peri- cardium, or of the thorax ? and thofe, which cover the upp parts of the body only, the anafarca of the lungs ? 6. When in the dropfy of the thorax, the patient endeavours tQ Sect. XXIX. 5. 2. ABSO: ITS. -61 to lie down., does not the extravafated fluid comprefs the upper ts of the bronchi', and to preclude the accefs of air to every part cf tfee lungs •, whilit in the perpendicular attitude the inferior parts of the lungs only are compreflecl ? Does notfome- thing fimilar to this occur in the anafarca of the lungs, when the difeafe is very great, and thus prevent thofe patients alfa from lying down ? 7. As a principal branch of the fourth cervical nerve of the left fide, after having joined a branch of the third and of the fec- cnd cervical nerves, descending between the Subclavian vein and artery, is received in a groove formed for it in the pericardium, and is obliged to make a confiderable turn outwards to go over the prominent part of it, where the point of the heart is lodged, in its courfe to the diaphragm ; and as the other phrenic nerve of the right fide has a flraight courfe to the diaphragm j and as many other considerable branches of this fourth pair of cervical nerves are fpread on the arms j does not a pain in the left arm diflinguifh a difeafe of the pericardium, as in the angina pet~t,o- jfis, or in the dropfy of the pericardium ? and does not a pain or weaknefs in both arms diftinguiih the dropfy of the thorax ? 8. Do not the dropfies of the thorax and pericardium fre- quently exift together, and thus add to the uncertainty and fa- tality of the difeafe ? 9. Might not the foxglove be ferviceable in hydrocephalus in- nus, in hydrocele, and in white iwellings of the joints ? VI* Of cold Sweats. There have been hiftories given of chronical immoderate fweatings, which bear fome analogy to the diabetes. Dr. Willis mentions a lady then Jiving, wrhofe fweats were for many years fo profufe, that all her bed-clothes were not only moiftened, but deluged with them every night ; and that many ounces, and Sometimes pints, of this fweat, were received in veffels properly placed, as it trickled down her body. He adds, that (lie had great thirft, had taken many medicines, and fubmitted to various rules of life, and changes of climate, but (till continued to have thefe immoderate fweats. Pharmac. ration, de fudore anglico. Dr. Willis has alfo obferved, that the fudor anglicanus which appeared in England, in 1483, and continued till 155 1, was in Come refpecb fimilar to the diabetes j and as Dr. Caius, who faw this difeafe, mentions the vifcidity, as well as the quantity of thefe fweats, and adds, that the extremities were often cold, when the internal parts were burnt up with heat and third:, With great and fpeedy emaciation and debility : there is great reaforz *6z RETROGRADE Sect. XXIX. 6. t , reafon to believe, that the fluids were abforbed from the cells of the body by the cellular and cyftic branches of the lymphatics, and poured on the Ikin by the retrograde motions of the cuta- neous ones. Sydenham has recorded, in the ftationary fever of the year ?68 ^, the vifcid fweats flowing from the head, which were prob- ably from the fame fourceas thofe in the fweating plague above mentioned. It is very common in dropfies of the cheft or lungs to have the difficulty of breathing relieved by copious fweats, flowing from the head and neck. Mr. P. about fifty years of age, had for many weeks been afflicted with anafarcaof his Jegs and thighs, attended with difficulty of breathing ; and had repeatedly been relieved by fquill, other bitters, and chalybeates. — One night the difficulty of breathing became (o great, that it was thought he mufl have expired ; but fo copious a fvveat came out of his head and neck, that in a few hours fome pints, by eftimation, were wiped off from th >fe parts, and his breath was for a time relieved. This dyfpncea and thefe fweats recurred at intervals, and after fome weeks he c to exift. The (kin of his head and neck felt cold to the hand, and appeared pale at the time thefe vweat td fo abundantly ; which is a proof, that they were produced by an inverted motion of the abforbents of thofe parts : for fweats, which are the confequence of an increafed action of the fanguiferous fyftem, are always attended with a warmth of the fkin, greater than is natural, and e. more florid colour ; as the fweats from exercife, or thofe that fucceed the cold fits of agues. Can any one explain how thefe partial fweats mould re- lieve the difficulty of breathing in anafarca, but by fuppofmg that the pulmonary branch of abforbents drank up the fluid in the ca\ ity of the thorax, or in the cells of the lungs, and threw it on the fkin, bv the retrograde motions of the cutaneous branch ? for, if we could fuppoie, that the increafed action of the cuta- neous glands or capillaries poured upon the ikin this fluid, pre- vicufly abforbed from the lungs ; why is not the whole furface of the body covered with fweat ? why is not the fkin warm ? Add to this, that the fweats above mentioned were clammy or gluti- nous, which the condenfed pcrfpirable matter is not; whence it would feem to have been a different fluid from that of common perfpiration. Dr. Dobfon, of Liverpool, has given a very ingenious expla- nation of the acid fweats, which he obferved in a diabetic patient -. — he thinks part of the chyle is fecreted by the Ikin, and after- wards undergoes an acetous fermentation. — Can the chyle get thither, but by an inverted motion cf the cutaneous lymphatics i in Sect. XXIX 7. 1. ABSORBENTS.- 2S5 in the fame manner as it is carried toVne bladder, by the inverted motions of the urinary lymphatics. Medic. Obfervat. and Enq. London, vol. v. Are not the cold fweats in fome fainting fits, and in dying people-, owing to an inverted motion of the cutaneous lymphat- ics ? for in thefe there can be no increafed arterial or glandular action. Is the difficulty of breathing, ariilng front ariafarca of the lungs,- relieved by fweats from the head and neck j whilft that difficul- ty of breathing, which arifes from a dropfy of the thorax, or peri- cardium, is never attended with thefe fweats of the head ? and thence can thefe difeafes be diiiinguimed from each other ? Do the periodic returns of nocturnal afthma rife from a temporary dropfy of the lungs, collected during their more torpid ftate in found fleep, and then re-abforbed by the vehement efforts of the difordered organs of refpiration, and carried off by the eogious- fweats about the head and neck ? More extenfive and accurate diflefrrons of the lymphatic fyf- tem are wanting to enable us to unravel thefe knots of fcience. VII. Tranflations of Matter, of Chyle, of Milky of Urine. Oper- ation of purging Drugs applied externally. 1. The tranflations of matter from one part of the body to another, can only receive an explanation from the doctrine of the occafional retrograde motions of fome branches of the lymph- atic fyftem : for how can matter, abforbed and mixed with the whole mafs of blood, be fo haftily collected again in any one part ? and is it not an immutable law, in animal bodies, that each gland can fecrete no other, but its own proper fluid ? which is, in part, fabricated in the very gland by an animal procefs, which it there undergoes : of thefe purulent tranflations innu- merable and very remarkable initances are recorded. i2. The chyle, which is feen among the materials thrown up y violent vomiting, or in purging ftools, can only come thither y its having been poured into the bowels by the inverted mo- ons of theladleals : for our aliment is not converted into chyle in the ftomach or inteftines by a chemical procefs, but is made in the very mouths of the la&eals ; or in the mefenteric glands ; in the fame manner as other fecreted fluids are made by an ani- mal procefs in their adapted glands. Here a curious phenomenon in the exhibition of mercury is worth explaining : — If a moderate dofe of calomel, as fix or ten grains, be fwallowed, and within one or two days a cathartic is given, a falivation is prevented : bu; after three or four days, a falivation RETROGRADE Sect. XXIX. 7. 3, falivatio mg come on, repeated purges every day, for a week or two, arc required to eliminate the mercury from the conflii tion. For this acrid metallic preparation, bei (orbed by t] mouths of the lacleals, continues, for a time arretted by the mef- enteric gland:";, (as the variolous or ve ifons fwell t fubaxiilar or inguinal glands) : and, during ation of cathartic, is returned into the inteftines by the inverted acti< of the lacleals, and thus carried out of the fyftem. Hence we underftand the ufe of vomits or purges, to thofe who have fwallowed either contagious or poifonous materials, even though exhibited a day or even two days after fuch acci- dents •, namely, that by the retrograde motions of the lacteais and lymphatics, the material Hill arretted in the mefenteric, or other glands, may be eliminated from the body. 3. Many inftances of milk and chyle found in ulcers are giv- en by Haller, El. Phyfiol. t. vii. p. 12, 23, which admit of no other explanation than by fuppofing, that the chyle, imbibed by one branch of the abforbent fyftem, was carried to the ulcer, by the inverted motions of another branch of the fame fyftem. 4. Mrs. P. on the fecond day after delivery, was i'eized with a violent purging, in which, though opiates mucilages, the bark, and teflacea were profulely ufed, continued many days, till at length (he recovered. During the time of this purging, no milk could be drawn from her breaits ; but the ftoods appeared like the curd of milk broken into fmall pieces. In this cafe, was not the milk taken up from the follicles of the pectoral glands, and thrown on the inteftines, by a retrogrefiion of the intcftinal ab- forbents ? for how can we for a moment fufpect that the mucous glands of the inteftines could feparate pure milk from the blood ? Dr. Smellie has obferved, that loofe ftools, mi with milk, which is curdled in the inteftines, frequently relieves the tuv- gefcency of the breaits of thofe who itudiouily repel their miik. Cafes in Midwifery, 43, No. 2. 1. 5. J. F. Meckel obferved in a patient, whofe urine 'was in fmall quantity and high coloured, that a copious fwe^it under the arm- pits, of a perfectly urinous fmell, ftained the linen ; which ceaf- i'd again when the uiual quantity of urine was difeharged by the urethra. Here we mult believe from analogy, that the urine was firit fecreted in the kidneys, then re-abforbed by the increaf- ed action of the urinary lymphatics, and laftly carried to the ax- illa: by the retrograde motions of the lymphatic branches of thofe parts. As in the jaundice it is Decenary, that the bile fhould firft be fecreted by the liver, and re-abforbed into the cir- culation, to produce the yellownefs of the fkin ; as was form- erly demonllraccd by the late Dr. Munro, (Edin. Medical Ef- fays) :t. XXIX. 7. 6. ABSORBENTS. i<$ fays) and if in this patient the urine had been feabforoed into the mafs of blood, as the bile in the jaundice, why was it not de- tected in other parts of the body, as well as in the arm-pits ? 6. Cathartic and vermifuge medicines applied externally to the abdomen, fcera to be taken up by the cutaneous branch of lymphatics, and poured on the interlines by the retrograde mo- tions of the lac?ceals, without having paiTed the circulation. For when the drallic purges are taken by the mouth, they ex- cite the lacteds of the interlines into retrograde motions, as ap- pears from the chyle, which is found coagulated among the fe- ces, as was (hewn above, (feci. 2 and 4.) And as the cutaneous lymphatics are joined with the lacteals of the interlines, by fre- quent anaftomofes ; it would be more extraordinary, when a ftrong purging drug, abforbed by the (km, is carried to the anaf- tomofmg branches of the lacleals unchanged, if it ihottld not excite them -into retrograde action as efhcaciouily, as if it was taken by the mouth, and mixed with the food of the flomach. VIII. Circuntflances by which ihe Fluids, that are effufed by the Retrograde Motions of the Abforbent Vefjels^ are difiinguifhed* T. We frequently obferve an unfual quantity of mucus of other fluids in fome difeafes, although the a£tion of the glands, by which thofe fluids are feparated from the blood, is not un- ufually increafed \ but when the power of abforption alone is di- minished. Thus the catarrhal humour from the noftrils cf fome, who ride in frofly weather 5 and the tears, which run fejMown the cheeks of thofe, who have an obflruclion of the punc- ta iaerymalia 5 and the ichor of thofe phagedenic ulcers, which are not attended with inflammation, are all inilances of this cir- cumftance. Thefe fluids however are eafily diflingrJfhed from ethers bv their abounding in amrnoniacal or muriatic falts ; whence they -inflame the circumjacent uz\a : thus in the catarrh the upper Jip becomes red and fwelled from the acrimony of the mucus, and patients complain of the faltnefs of its ta(te. The eyes and cheeks are red with the corrofive tears, and the ichor of fome herpetic eruptions erodes far and wide the contiguous parts, and is pungently fait to the tafle, as fome patients have informed me. Whilft, on the contrary, thofe fluids, which are effufed by the retrograde action of the lymphatics, are for the moft part mild and innocent ; as water, chyle, and the natural mucus : or they take their properties from the materials previoufiy ab- sorbed, as in the coloured or vinous urine, or that fcented with afparagus, defcribed before. Vol. I. L L 2. Whenever 256 RETROGRADE Sect. XXIX. fc j0 ?.. Whenever the fecretion of any fluid is increafed, there 15 .it the fame time an increafed heat in the part ; for the fecreted fluid, as the bile, did not previou fly exift in the mafs of blood, but a new combination is produced in the gland. Now as folu- tions are attended with cold, fo combinations are attended with heat ; and it is probable the fum of the heat given out by all the fecreted fluids of animal bodies may be the caufe of their gen- eral heat above that of the atmofphere. Hence the fluids derived from increafed fcgre tions are read- ily diftinguifhed from thofe originating from the retrograde mo- tions of the lymphatics : thus an increafe of heat either in the difeafed parts, or difFufed over the whole body, is perceptible, when copious bilious flools are confequent to an inflamed liver 5 or a copious mucous falivation from the inflammatory angina. 3. When any fecreted fluid is produced in an unufual quanti- ty, and at the fame time the power of abforption is increafed in equal proportion, not only the heat of the gland becomes more intenfe, but the fecreted fluid becomes thicker and milder, its thinner and faline parts being re-abforbed : and thefe are di tinguifhable both by their greater confidence, and by their heat, from the fluids, which are efFufed by the retrograde motions of the lymphatics *, as is obfervable towards the termination of gon- orrhoea, catarrh, chincongh, and in thofe ulcers, which are faid to abound with laudable pus. 4. When chyle is obferved in (tools, or among the materials ejected by vomit, we may be confident it muft have been brought thither by the retrograde motions of the lacleals •, for chyle does not previoufly exift amid the contents of the intef- tines, but is made in the very mouths of the lacTeals, as was be- fore explained. c. When chyle, milk, or other extraneous fluids are found in the urinary bladder, or in any other excretory receptacle of a gland ; no one can for a moment believe, that thefe have been collected from the mafs of blood by a morbid fecretion, as it con* tradicts all analogy. Aurea durae 1 ferj.nt qtjertSft ? Narcifco floreat alnus ? Pinguia corticibiiB fudent ele&ra myricx ? ViRGIL. IX. Retrograde Motions of Vegetable Junes, There are befides fome motions of the fap of vegetables, which bear analogy to our prefent fubjecl ; and as the vegeta- ble tribes are bv many philofophers held to be inferior animals, it Sect. XXIX. 10. i. ABSORBENTS. *67 It may be a matter of curiofity at leaft to obferve, that their ab~ forbent vefTels feem evidently, at times, to be capable of a retro- grade motion. Mr. Perault cut off a forked branch of a tree, with the leaves on ; and inverting one of the forks into a veffel of water, obferved, that the leaves on the other branch continu- ed green much longer than thofe of a fimilar branch, cut off from the fame tree ; which mews, that the water from the vef- fel was carried up one part of the forked branch, by the retro- grade motion of its verTels, aiid fupplied nutriment forne time to the other part of the branch, which was out of the water. And the celebrated Dr. Hales found, by numerous very accurate ex- periments, that the fap of trees rofe upwards during the warmer hours of the day, and in part defcended again during the cooler ones. Vegetable Statics. It is well known that the branches of willows, and of many other trees, will either take root in the earth or ingraft on other trees, fo as to have their natural direction inverted, and yet flour* ilh with vigour. Dr. Hope has alfo made this pleafing experiment, after the manner of Hales — he has placed a forked branch, cut from one tree, erecl: between two others ; then cutting off a part of the bark from one fork applied it to a fimilar branch of one of the trees in its vicinity •, and the fame of the other fork ; fo that a t-ree is feen to grow fufpended in the air, between two other trees ", which fupply their fofter friend with due nourishment., Miranturque novas frondes, et non fua poma. All thefe experiments clearly evince, that the juices of vege- tables can occasionally pafs either upwards or downwards in. their abforbent fyftem of veffels. X. Objections anfwered. The following experiment, at firft view, would feem to in- validate this opinion of the retrograde motions of the lymphatic vefTels, in fome difeafes. About a gallon of milk having been given to a hungry fvvine,he was fuffered to live about an hour, and was then killed by a ftroke or two on his head with an axe. — On opening his belly the lac- teals were well feen filled with chyle ; on irritating many of the branches of them with a knife, they did not appear to emp- ty themfelves nattily ; but they did however carry forwards their contents in a little time. I then pafTed a ligature round feveral branches of lacteals, and irritated them much with a knife beneath the lieature, but couli 203 RETROGRADE Sect. XXIX. n. r. could not make them regurgitate their contained fluid into the bowels. I am not indeed certain, that the nerve was not at the fame time included in the ligature, and thus the lymphatic rendered unwritable orlifelefs ; but this however is certain, that it is not any quantity of any ftimulus, which induces the vefieis of animal bodies to revert their motions ; but a certain quantity of a cer- tain ftimulus, as appears from wounds in the ftomach, which do not produce vomiting ; and wounds of the inteftines, which do not produce the cholera morbus. At Nottingham, a few years ago, two lhoemakers quarrelled, and one of them with a knife, which they ufe in their occupation, flubbed his companion about the region of the ftomach. On opening the abdomen of the wounded man after his death the food and medicines he had taken were in part found in the cav- ity of the belly, on the outfide of the bowels ; and there was a wound about half an inch long at the bottom of the ftomach ; which I fuppofe was diftended with liquor and food at the time of the accident ; and thence was more liable to be injured at its bottom : but during the whole time he lived, > was abov.t ten days, he had no efforts to vomit, nor ever even complained of being fick at the ftomach ! Other cafes fimilar to this are men- tioned in the philofophical tranla£tions. Thus, if you vellicate the throat with a feather,, naufea is pro- duced ; if you wound it with a penknife, pain is induced, but not ftcknefs. So if the foles of the feet of children or their arm- pits are tickled, convulfive laughter is excited, which ceafes the moment the hand is applied, fo as to rub them more forcibly. The experiment therefore above related upon the lacleals of a dead pig, which were included in a ftricl ligatuve, proves nothing ; as it is not the quantity, but the kind of ftimulus, which excites the lymphatic veilels into retrograde motion. XL The Canfes luhich induce the Retrograde Motions of Animal Vef~ fels ; and the Medicines by which the Natural Motions arc rejlored. i. Such is the conftruclion of animal bodies, that all their parts, which are fubjecled to lefs ftimuli than nature defigned, perform their functions with lefs accuracy : thus, when too wa- tery or too acefeent food is taken into the ftomach, indigeftion, and flatulency, and heartburn lucceed. 2. Another law of irritation, connate with our exiftence, is, t!i;it all thofe parts of the body, which have previously been ex- poled to loo >/' cat a quantity of iuch ftimuli, as ftrongly affect m, become for fomc time afterwards difobedient to the nat- ural Sect. XXIX. n. J; ABSORBENTS. 269 ura! quantity of their adapted ftimuli. — Thus the eye is inca- pab-e of feeing objects in nn obfeure room, though the iris is quite dilated, after having been expoied to the meridian fun. 3. There is a third law of irritation, that all the parts of our todies, which have been lately iubjected to lefs ftimulus, than they have been accu-ftomed to, when they are expofed to their ufuii quantity of ftimulus, are excited into more energetic mo- tions : thus when we come from a dufky cavern into the glare of daylight, our eyes are dazzled ; and after emerging from the cold bath, the fkin becomes warm and red. 4. There is a fourth law of irritation, that all the parts of our bodies, which are fubjectcd to ft ill ftronger ftimuli for a length of time, become torpid, and refufe to obey even thefe llronger ftimuli ; and thence do their offices very imperfectly. — Thus, if any one looks earneftly for fome minutes on an area, an inch di- ameter, of red filk, placed on a meet of white paper, the image of the filk will gradually become pale, and at length totally vaniih. 5. Nor is it the nerves of fenfe alone, as the optic and audi- tory nerves, that thus become torpid, when the ftimulus is with- drawn or their irritability decreafed ; but the motive mufcles, when they are deprived of their natural ftimuli, or of their irri- tability, become torpid and paralytic ; as is feen in the tremulous hand of the drunkard in a morning °, and in the awkward ftep of age. The hollow mufcles alfo, of which the various veiTels of the body are constructed, when they are deprived of their natural ftimuli, or of their due degree of irritability, not only become tremulous, as the arterial pulfations of dying people ; but alfo frequently invert their motions, as in vomiting, in hyfteric fuffo- cations, and diabetes above defefibed. I muft beg your patient attention, for a few moments, whilft I endeavour to explain, how the retrograde actions of our hol- low mufcles are the confequence of their debility; as the tremu- lous actions of the folid mufcles are the confequence of their de- bility. When, through fatigue, a mufcle can act no longer ; the antagonift mufcles, either by their inanimate eiafticity, or by their animal action, draw the limb into a contrary direction : in t\ie folid mufcles, as thofe of locomotion, their actions are aflb- ciated in tribes, which have been accuftomed to fynchronous ac- tion only ; hence when they are fatigued, only a fingle contrary effort takes place ; which is either tremulous, v/hen the fatigued muiclss are again immediately brought into action ; or it is a pandiculation, or ftretching, where they are not immediately in brought into action. Now the motions of tie hollow mufcles, as they in general propel s7o RETROGRADE Sect. XXIX. u.& propel a fluid along their cavities, are afibciated in trains, which have been accuflomed to fucceffive actions : hence when one ring of fuch a mufcle is fatigued from its too great debility, and is brought into retrograde aclion, the next ring from its aflbcia- tion falls fucceflively into retrograde aclion ; and fo on through- out the whole canal. Gee Seel:. XXV. 6. 6. But as the retrograde motions of the ftornach, cefophagus, and fauces in vomiting are, as it were, apparent to the eye ; we {hall confider this operation more minutely, that the fimilar op- erations in the more recondite parts of our fyftem may be eafier underftood. From certain naufeous ideas of the mind, from an ungrateful tafte in the mouth, or from foetid fmells, vomiting is fometimes inftantly excited ; or even from a ftroke on the head, or from the vibratory motions of a fhip ; all which originate from afToci- ation, or fympathy. See Seel:. XX. on Vertigo. But when the ftornach is fubjefced to a lefs ftimulus than is natural, according to the firft law of irritation mentioned above, its motions become difturbed, as in hunger ; firft pain is produ- ced, then ficknefs, and at length vain efforts to vomit, as many authors inform us. But when a great quantity of wine, or of opium, is fwallow- ed, the retrograde motions of the ftornach do not occur till after feveral minutes, or even hours 5 for when the power of fo ftrong a ftimulus ceafes, according to the fecond law of irritation, men- tioned above, the periftaltic motions become tremulous, and at length retrograde ; as is well known to the drunkard, who on the next morning has ficknefs and vomitings. When a ftill greater quantity of wine, or of opium, or when naufeous vegetables, or ftrong bitters, or metallic falts, are taken into the ftornach, they quickly induce vomiting ; though all thefe in lefs dofes excite the ftornach into more energetic action, and ftrengrhen the digeftion ; as the flowers of chamomile, and the vitriol of zinc : for, according to the fourth law of irritation, the ftornach wiil not long be obedient to a ftimulus fo much great- er than is natural •, but its aclion becomes firft tremulous and then retrograde. 7. When the motions of any vefTels become retrograde, lefs heat of the body is produced ; for in paroxyfms of vomiting, of hyf- teric affections, of diabetes, of afthma, the extremities of the body are cold: hence we may conclude, that thefe fymptoms arife from the debility of the parts in aclion ; for an increafe of mufcular action is always attended with increafe of heat. 8. But as animal debility is owing to defect of ftimulus, or to defcci o£ irritability, as fhewn above, the method of cure iseafily deduced ;. £ect. XXIX. i r . 8. ABSORBENTS. 2 7 i deduced : when the vafcular mufcles are not excited into their due action by the natural ftimuli, we mould exhibit thofe med- icines, which poiTefs a ftill greater degree of ftimulus ; amongft thefe are the feetids, the volatiies, aromatics, bitters, metallic falts, opiates, wine, which indeed fhould be given in fmall doles, and frequently repeated. To thefe mould be added conftant^ but moderate exercife, cheerfulnefs of mind, and change of coun- try to a warmer climate ;• and perhaps occalionally the external ftimulus of blifters. It is aifo frequently ufefu! to dhnimih the quantity of natur- al ftimulus for a ihort time, by which afterwards the irritability of the fyftem becomes increafed ; according to the third law of irritation above mentioned, hence the ufe of baths fomewhat cold- er than animal heat, and of equitation in the open air. The catalogue of difeafes Giving to the retrograde inotions of lymphat- ics is here omitted, as it ivill appear in another place in this *work. The following is the conclufion to this thefts of Mr Charles Darwin. Thus have I endeavoured in a con'cife manner to explain the numerous difeafes, which deduce their origin from the inverted motions of the hollow mufcles of our bodies : and it is probable, that Saint Vitus's dance, and the Hammering of fpeech, origin- ate from a fimilar inverted order of the affociated motions of fome of the folid mufcles ; which, as it is foreign to my prefent purpofe, I (hall not here difcufs. I beg, illuftrious profefTors, and ingenious fellow-ftudents, that you will recollect how difficult a ta& I have attempted, to evince the retrograde motions of the lymphatic vefiels, when the vefTels themfelves for fo many ages efcaped the eyes and glaffes of phi- lofophers : and if you are not yet convinced of the truth of this theory, hold, I entreat you, your minds in fufpenfe, till Anat- omy draws her fword with happier omens, cuts afunder the knots, which entangle Physiology ; and, like an augur infpectmg the immolated viclim, announces to mankind the wifdom of HEAVEN, SECT. 272 PARALYSIS Sect. XXX, i. SECT. XXX. ' PARALYSIS. OF THE LIV^R AND KIDNEY I. Bile-duels lefs irritable after having been fiimulaied much. i„ Jaundice front paralyfts of 'the bile-duds cured by t ;i. 3. From bile-fto?ies. Experiments on bile-Jlonc. Oil vomit* 4. Palfy of the liver, two cafes. 5. Scirrhfty of the / 6. Large livers of geefe. II. Paralyfts of the kidneys. III. ' Story of Prometheus. 1. From the ingurgitation of fpirituous liquors into the from* rcH and duodenum, the termination of the common bile-duct in that bowel becomes Simulated into unnatural action, and a ; ater quantity of bile is produced from all the fecretory vefTels the liver, by the arlbciation of their motions with thofe of their excretory ducts j as has been explained in Section XXIV. and XXV. but as all parts of the body, that have been affected with ftronger ftimuli for any length of time, become lefs fuf- ceptible of motion, from thejr natutal weaker ftimuli, it follows, fhat the motions of the fecretovy veffels, and in confequence the \ fecretion of bile, is lefs than is natural during the intervals fobriety. 2. If this ingurgitation of fpirituous liquors has be; daily continued in considerable quantity, and is then fuddenly intermitted, a languor or paralyfis of the common bile-duct induced \ the bile is prevented from being poured into the in reftines ; and as the bilious abforbents are ftimulated into flrong er action by its accumulation, and by the acrimony or vifcidi which it acquires by delay, it is abforbed, and carried to the v receptacle of the chyle ; or otbervvife the fecretory veiTels of u liver, by the above-mentioned ftimulus, invert their motions, and ., regurgitate their contents into the blood, as fometimes happei to the tears in the lacrymal fack, fee S^ct. XXIV. 2. 7. and one kind of jaundice is brought on. There is reafon to believe, that the bile is rnoft frequently 1 fumed into the circulation by the inverted motions of thefe he- patic glands, for the bile does not feem liable to be abforbed by the lymphatics, for it foaks through the gall-ducts, and is fre- quently found in the cellular membrane. This kind of jaundice is not generally attended with pain, neither at the extremity ot the bile-duct, where it enters the duodenum, nor on the region of the gall-bladder. Mr. S. a gentleman between forty and fifty years of age, had had the jaundice about fix weeks, without pain, ficknefs, or fe- ver ; Sect. XXX. i. 3. OF THE LIVER. 273 ver ; and had taken emetics, cathartics, mercurials, bitters, chalybeates, efTential oil, and aether, without apparent advan- tage. On a fuppofition that the obftruction of the bile might be owing to the paralyfis, or torpid action of the common bile- duel:, and the ftimulants taken into the ftomach feeming to have no effect, I directed half a fcore fmart electric (hocks from a coated bottle, which held about a quart, to be pafTed through the liver, and along the courfe of the common gall-duct, as near as could be gueffed, and on that very day the (tools became yel- low ; he continued the electric (hocks a few days more, and his (kin gradually became clear. 3. The bilious vomiting and purging, that affects fome peo- ple by intervals of a few weeks, is a lefs degree of this difeafe ; the bile-duct is lefs irritable than natural, and hence the bile becomes accumulated in the gall-bladder, and hepatic ducts, till by its quantity, acrimony or vificidity, a greater degree of irritation is produced, and it is fuddenly evacuated, or laftlv from the abforption of the more liquid parts of the bile, the re- mainder becomes infpifTated, and chryftallizes into mafles too large to pafs, and forms another kind of jaundice, where the bile-duct is not quite paralytic, or has regained its irritability. This difeafe is attended with much pain, which at (irft is feife at the pit of the ftomach, exactly in the centre of the body, where the bile-duct enters the duodenum ; afterwards, when the fize of the bile-ftones increafe, it is alfo felt on the right fide, where the gall-bladder is fituated. The former pain at the pit of the ftomach recurs by intervals, as the bile-done is pu(h- ed againft the neck of the duct \ like the paroxyfms of the ftone in the urinary bladder, the other is a more dull and conftant pain. Where thefe bile-ftones are too large to pafs, and the bile- ducts poffefs their fenfibility, this becomes a very painful and hopelefs difeafe. I made the following experiments with a view to their chemical folution. Some fragments of the fame bile-ftone were put into the weak fpiiit of marine fait, which is fold in the (hops ; and into folu- tion of mild alcali \ and into a folution of cauftic alcali j and into oil of turpentine ; without their being diflblved. All thefe mixtures were after fome time put into a heat of boiling water, and then the oil of turpentine diflblved its fragments of bile- ftone, but no alteration was produced upon thofe in the other liquids except fome change of their colour. Some fragments of the fame bile-ftone were put into vitriolic sether, and were quickly diflblved without additional heat. Might not rether mixed with yolk of egg or with honey be given advantageoullv in bilious concretions ? Vol.. I. Mm I 274 PARALYSIS Sect. XXX. i. 4. I have in two in (lances feen from thirty to fifty bile-Hones come away by ftool, about the fize of large peas, after having given fix grains of calomel in the evening, and four ounces of oil of almonds or olives on the fucceeding morning. I have alfo given half a pint of good olive or almond oil as an emetic during the painful fit, and repeated it in half an hour, if the firfr. did not operate, with frequent good effect. 4. Another difeafe of the liver, which I have feveral times ob- ferved, conlifts in the inability or paralyfis of the fecretory vef- -fels. This difeafe has generally the fame caufe as the preceding one, the too frequent potation of fpirituous liquors, or the too fudden omiflion of them, after the habit is confined ; and is greater or lefs in proportion, as the whole or a part of the liver is affected, and as the inability or paralyfis is more or lefs com- plete. This palfy of the liver is known from thefe fymptoms, the pa-u tients have generally parTed the meridian of life, have drunk fermented liquors daily, but perhaps not been opprobrious drunkards ; they lofe their appetite, then their flefh and flrength diminifh in confequence, there appears no bile in their (tools, nor in their urine, nor is any hardnefs or fwelling perceptible in the region of the liver. But what is peculiar to this difeafe, and diftinguifhes it from all others at the fiift glance of the eye, is the bombycinous colour of the fkin, which, like that of full- grown filk worms, has a degree of tranfparency with a yellow tint not greater than is natural to the ferum of the blood. Mr. C. and Mr. B. both very ftrong men, between fifty and fixty years of age, who had drunk ale at their meals inftead of fmall beer, but were not reputed hard-drinkers, fuddenly became weak, loft their appetite, flefh and ftrength, with all the fymp- toms above enumerated, and died in aboutrtvvo months from the beginning of their malady. Mr. C. became anafarcous a few days before his death, and Mr. B. had frequent and great hem- orrhages from an iiiue, and fome parts of his mouth, a few- days before his death. In both thefe cafes calomel, bitters, and chalybeates were repeatedly ufed without efieft. One of the patients defcribed above, Mr. C. was by trade 2 plumber ; both of them could digefl no food, and died apparent- ly for want of blood. Might not the transfufion of blood be ufed in thefe cafes with advantage ? 5. When the paralyfis of the hepatic glands is lefs complete, or lefs univerfal, a fcirrholity of fome part of the liver is indu- ced ; for the fecretory veiTels retaining fome of their living pow- er take up a fluid from the circulation, without being fufheient- ly irritable to carry it forwards to their excretory ductd : hence the Sect. XXX. i. 6. OF THE LIVER. 275 the body, or receptacle of each gland, becomes inflated, and this .diftention increafes, till by its very great ftimulus inflammation is produced, or till thofe parts of the vifcus become totally paralyt- ic. This difeafe is diftinguifhable from the foregoing by the palpable hardnefs or largenefs of the liver ; and as the hepatic glands are not totally paralytic, or the whole liver not affected, fome bile continues to be made. The inflammations of this vifcus, confequent to the fcirrhofity of it, belong to the difeafes of the fenfitive motions, and will be treated of hereafter. 6. The ancients are faid to have pofTerTed an art of increasing the livers of geefe to a fize greater than the remainder of the goofe. Martial. 1. 13. epig. 58. — This is laid to have been done by fat and figs. Horace. 1. 2. fat. 8. — Juvenal lets thefe large livers before an epicure as a great rarity. Sat. 5. 1. 114; and Perfius, fat. 6. 1. 71. Pliny fays thefe large goofe-livers were foaked in mulled milk, that is, I fuppofe, milk mixed with honey and wine ; and adds, "that it is uncertain whether Scipio Metellus, of confular dignity, or M. SefHus, a Roman knight, was the great difcoverer of this excellent dim." A modern traveller, I believe Mr. Brydone, aflerts that the art of enlarging the livers of geefe ftili exifts in Sicily ; and it is, to be lamented that he did not import it into his native country, as fome meth- od of affecting the human liver might perhaps have been col- lected from it ; befides the honor he might have acquired in improving our giblet pies. Our wifer caupones, I am told, know how to fatten their fowls, as well as their geefe, for the London markets, by mix- ing gin inftead of figs and fat with their food ; by which they are faid to become fleepy, and to fatten apace, aud probably ac- quire enlarged livers ; as the fwine are aiTerted to do, which are fed on the fediments of barrels in the diftilleries ; and which fo frequently obtains in thofe, who ingurgitate much ale, or wine, or drams. II. The irritative difeafes of the kidneys, pancreas, fpleen, and other glands, are analogous to thofe of the liver above de- scribed, differing only in the confequences attending their ina- bility to action. For inflance, when the fecretory veffels of the kidneys become difobedient to the ftimulus of the palling cur- rent of blood, no urine is feparated or produced by them ; their excretory mouths become filled with concreted mucus, or cal- culous matter, and in eight or ten days ftupor and death fuper- vene in confequence of the retention of the feculent part of the blood. This difeafe in a {lighter degree, or when only a part of the kidney is affected, is fucceeded by partial inflammation of the kidney *7<5 PARALYSIS, &c. Sect. XXX. 3. kidney in confequence of previous torpor. In that cafe greater actions of the fecretory veflels occur, and the nucleus of gravel is formed by the inflamed mucous membranes of the tubuli uriniferi, as farther explained in its place. This torpor, or paralyfis of the fecretory veffels of the kid- neys, like that of the liver, owes its origin to their being previ- oufly habituated to too great ft imul us; which in this country is generally owing to the alcohol contained in ale or wine ; and hence mull be regiftered amongft the difeafes owing to inebrie- ty ; though it may be caufed by whatever occafionally inflames the kidney ; as too violent riding on horfeback, or the cold from a damp bed, or by fleeping on the cold ground ; or perhaps by drinking in general too little aqueous fluids. III. I fhall conclude this feclion on the difeafes of the liver induced by fpirituous liquors, with the well known (lory of Prometheus, which feems indeed to have been invented by phy. ficians in thofe ancient times, when all things were clothed in hieroglyphic, or in fable. Prometheus was painted as (tealing fire from heaven, which might well reprefent the inflammable fpirit produced by fermentation ; which may be faid to animate or enliven the man of clay : whence the conquefls of Bacchus, as well as the temporary mirth and noife of his devotees. But the after punifhment of thofe, who (leal this accurfcd fire, is -a vulture gnawing the liver •, and well allegorifes the poor inebri- ate lingering for years under painful hepatic difeafes. When the expediency of laying a further tax on the diflillation of fpir- ituous liquors from grain was canvafTed before the Houfe of Commons fome years ago, it was faid of the diilillers, witli great truth, " They take the bread from the people, and convert it into poifon .'" Yet is this manufactory of difeafe permitted to con- tinue, as appears by its paying into the treafury above 900,000/. near a million of money annually. And thus, under the names of rum, brandy, gin, whifky, ufquebaugh, wine, cyder, beer, and porter, alcohol is become the bane of the Chriftian world, as opium of the Mahometan. Evoe ! parce, Liber, Par^e, gravi metuende thyrfo ! Hor. SECT. Sect. XXXI. i. OF TEMPERAMENTS. 277 SEC T. XXXI. OF TEMPERAMENTS. I. The temperament of decreased irritability known by weak puff, large pupils of the eyes, cold extremities. Are generally fuppofed to be too irritable. Bear pain better than labour. Natives >f North-America contra/led with thofe upon the coajl of Africa. Narrow and broad fhouldered people. Irritable conjtitutkm bear labour better than pain. II. Te?nperament of increafed fenjibility. Liable to intoxication, to inflammation, hamoptoe, gutta ferena, en- thufiafm, delirium, reverie. Thefe con/litutions are indolent to voluntary exertions, and dull to irritations. The natives cf South- America, and brute animals of this temperament. III. Of in- creafed voluntarity ; thefe are fubjetl to locked jaw, coinnrf::r.s, epi'epfy, mania. Are very aclive, bear cold, hunger, fatigue. Are fuited to great exertions. This temperament diftinguijfhts mankind from other animals. IV. Of increafed affectation. Thefe have great memories, are liable to quartan agues, ana flronger fympathies of parts ivith each other. V. Change temperaments into one another. Ancient writers have fpoken much of temperaments, hat without fufficient precifion. By temperament of the fyftcm mould be meant a permanent predifpoiition to certain claiies of difeafes : without this definition a temporary predifpofition to every diftincr, malady might be termed a temperament. There are four kinds of conftitution, which permanently deviate from good health, and are perhaps fufficiently marked to be diflin- guilhed from each other, and constitute the temperaments or predifpofitions to the irritative, fenfitive, voluntary, and aiToci- ate claffes of difeafes. I. The Temperament of decreafed Irritability. The difeafes, which are caufed by irritation, moft frequently originate from the defeel: of it ; for thofe, which are immedi- ately owing to the excefs of it, as the hot fits of fever, aregen?.!-- ally occafioned by an accumulation of fenforial power in confe- quence of a previous defect of irritation, as in the preceding cold fits of fever. Whereas the difeafes, which are caufed bj- fenfation and volition, moft frequently originate from the excels of thofe fenforial powers, as will be explained below. The temperament of decreafed irritability appears from th^ following -»7S OF TEMPERAMENTS. Sect. XXXI. u following circumftances, which (hew that the mufcular fibres or organs of tenfe are liable to become torpid or quiefcent from lefs defect of ftimulation than is productive of torpor or quief- cence in other conltitutions. i. The firft is the weak pulfe, which in fome conltitutions is at the fame time quick. 2. The next mod marked criterion of this temperament is the largenefs of the aperture of the iris, or pupil of the eye, which has been reckoned by fome a beauti- ful feature in the female countenance, as an indication of deli- cacy, but to an experienced obferver it is an indication of de- bility, and is therefore a defect, not an excellence. The third molt marked circumftance in this conftitution is, that the ex- tremities, as the hands and feet, or nofe and ears, are liable to become cold and pale in fituations in refpect to warmth, where thofe of greater ftrength are not affected. Thofe of this tem- perament are fubject to hyfteric affections, nervous fevers, hy- drocephalus, fcrofula, and confumption, and to all other difeafes of debility. Thofe, who poflefs this kind of conftitution, are popularly Tuppofed to be more irritable than is natural, but are in reality Jeis fo. This miftake has arifen from their generally having a greater quicknefs of pulfe, as explained in Sect. XII. 1. 4. XII. 3. 3 j but this frequency of pulfe is not neceflary to the temper- ament, like the debility of it. rions of this temperament are frequently found amongft the fofter fex, and amongft narrow mouldered men ; who are laid to bear labour worfe, and pain better than others. This jail circumftance is fuppofed to have prevented the natives of North America from having been made flaves by.the Europeans. They are a narrow-mouldered race of people, and will rather expire under the lafh, than be made to labour. Some nations of Afia have fmail hands, as may be feen by the handles of their fcymetars; which with their narrow flioulders (hew, that they have not been accuftomed to fo great labour with their hands and arms, as the European nations in agriculture, and thofe on the coafls of Africa in fwimming and rowing. Dr. Mannin - ham, a popular accoucheur in the beginning of this century, obfv-rves in his aphorifms, that oroad-fhouldered men procreate broad-ih uldered children. Now as labour ftrengthens the mufcleg employed, and nrcreafes their bulk, it would feein that a few generations of labour or of indolence may in this refpe/ft change the form and temperament of the bod v. On the contrary; thofe who are happily poffefled of a great de- gree of irritability, bear labour better than pain •, and arc ftrong, •ve, and ingenious. But there is not properly a temperament of Sect. XXXL i. OF TEMPERAMENTS, 27^ of increafed irritability tending to difeafe, becaufe an increafed quanity of irritative motions generally induces an increafe of pleasure or pain, as in intoxication, or inflammation -, and then thv. new motions are the immediate confequences of increafc-i fenfation, not of increafed irritation ; which have hence been fa perpetually confounded with each other. II. Temperament of Senfibiliiy* There is not properly a temperament, or a predifpofition to difeafe, from decreafed fenfibility, iince irritability and not fenfi- bility is immediately neceflary to bodily health. Hence it is the cxeefs of fenfation alone, as it is the defedt of irritation, that moil frequently produces difeafe. This temperament of increafed fen- fibility is known from the increafed activity of all thofe motions of the organs of fenfe and mufcles, which are exerted in confe- quence of pleafure or pain, as in the beginning of drunkennefs* and in inflammatory fever. Hence thofe of this conftitution are liable to inflammatory difeafes, as hepatitis •, and to that kind of confumption which is hereditary, and commences with flight repeated hxmoptoe. They have high-coloured lips, fre- quently dark hair and dark eyes with large pupils, and are in that cafe fubjecr. to gutta ferena. They are liable to enthufiafm, delirium, and reverie. In this laft circumlrance they are liable to ftart at the clapping of a door ; becaufe the more intent any one is on the pafnng current of his ideas, the greater furprife he experiences on their being diffevered by fome external violence* as explained in Sedt. XIX. on reverie. As in thefe conftitutions more than the natural quantities of fenfitive motions are produced by the increafed quantity of fen- fation exiiling in the habit, it follows, that the irritative motions will be performed in fome degree with lefs energy, owing to the great expenditure of fenforial power on _the fenfitive ones. Hence thofe of this temperament do not attend to flight ftimu- lations, as explained in Sect. XIX. But when a ftimulus is fo great as to excite fenfation, it produces greater fenfitive actions of the fyftem than in others ; fuch as delirium or inflammation. Hence they are liable to be abfent in company ; lit or lie long in one pofture ; and in winter have the fkin of their legs burnt into various colours by the fire. Hence alio they are fearful of pain ; covet mufic and fleep ; and delight 111 poetry and romance. As the motions in confequence of fenfation are more than nat- ural, it alfo happens from the greater expenditure of fenforial power on them, that the voluntary motions are lefs eafily exerted. Hence *8g OF TEMPERAMENTS. Sect. XXXI. 3, Hence the fubjecls of this temperament are indolent in refpect to all voluntary exertions, whether of mind or body. A race of people of this description feems to have been found by the Spaniards in the iflands of America, where they firfl: landed, ten of whom are faid not to have confumed more food than one Spaniard, nor to have been capable of more than one tenth of the exertion of a Spaniard. Robertfon's Hiftory. — In a date fimilar to this the greateft part of the animal world pafs their lives, between fleep and inactive reverie, except when they are excited by the call of hunger. III. The Temperament ofincreafed Voluntarity* Those of this conftitution differ from both the lad mentioned in this, that the pain, which gradually fubfides in the firfl, and is productive of inflammation or delirium in the fecond, is in this fucceeded by the exertion of the mufcles or ideas, which are mod frequently connected with volition; and they are thence fubject to locked jaw, convulfions, epilepfy, and mania, as explained in Sect. XXXIV. Thole of this temperament at- tend to the flighted irritations or fenfations, and immediately ex- ert themfelves to obtain or avoid the objects of them ; they can at the fame time bear cold and hunger better than others, of which Charles the Twelfth of Sweden was an inftance. They are fuited and generally prompted to all great exertions of genius or labour, as their defires are more extenfive and more vehe- ment, and their powers of attenden and of labour greater. It is this facility of voluntary exertion, which diftinguifhes men from brutes, and which has made them lords of the creation. IV. The Temperament of increeifed AJJbc'iation. This conftitution confifts in the too great facility, with which the fibrous motions acquire habits of aiTociation, and by which thefe afTociaritons become proportionably flronger than in thofe of the other temperaments. Thofe of this temperament are flow in voluntary exertions, or in thofe dependent on fenfation, or on irritation. Hence great memories have been faid to be attended with lefs fenfe and lefs imagination from Ariftotte down to the prefent time ; for by the word memory thefe writers only underfiood the unmeaning repetition of words or numbers in the order they were received, without any voluntary efforts of the mind. In this temperament thofe adociations of motions, which are commonly termed fympathics, act with greater certainty and energy, Sect. XXXI. 5. OF TEMPERAMENTS. 281 energy, as thofe between difturbed vifion and the inverfion of the motion of the ftomach, as in fea ficknefs ; and the pains in the fhoulder from hepatic inflammation. Add to this, that the catenated circles of actions are of greater extent than in the other conftitutions. Thus if a ftrong vomit or cathartic be exhibited in this temperament, a fmaller quantity will produce as great an effect, if it be given fome weeks afterwards; whereas in other temperaments this is only to be expected, if it be exhibited in a few days after the firft dofe. Hence quartan agues are formed in thofe of this temperament, as explained in Section XXXII. on difeafes from irritation, and other intermittents are liable to recur from flight caufes many weeks after they have been cured by the bark. V. The firft of thefe temperaments differs from the ftandard of health from defect, and the others from excefs of fenforial power ; but it fometimes happens that the fame individual, from the changes introduced into his habit by the different feafons of the year, modes or periods of life, or by accidental difeafes, paffes from one of thefe temperaments to another. Thus a long ufe of too much fermented liquor produces the temperament of increafed fenfibility ; great indolence and folitude that of de- creafed irritability ; and want of the necefTaries of life that of increafed voluntarity. Vol. t N n SECT. 232 DISEASES Sect. XXXII. i. SECT. XXXII. DISEASES OF IRRITATION. I. Irritative fevers withflrong pulfe. With weak pulfe. Symp- toms of fever. Their fource, II. I . ghiick pulfe is Giving to decreafed irritability. 2. Not infeep or in apoplexy. 3. From inanition. Owing to deficiency of fenforial power. III. 1. Caufes of fever. From defect of heat. Heat from fecret ions. Pain of cold in the loins and forehead. 2. Great expenfe of fenforial power in the vital motions. Im me if ion in cold water. Succeeding glow of heat. Difficult refpiration in cold bathing explained. Why the cold bath invigorates. Bracing and relaxation are mechanical terms. 3. Ufes of cold bathing. Ufes of cold air in fevers. 4. Ague fits from cold air. Whence their periodical returns. IV. Defect of diflention a caufe of fever. Deficiency of blood. Trans- fufion of blood. V. 1. Defied of momentum of the blood from me- chanic Jlimuli. 2. Air injected into the blood-veffels. 3. Exer- cifie increafies the momentum of the blood. 4. Sometimes bleeding increafes the momentum of it. VI. Influence of the fun and moon on difieafies. The chemical Jlimulus of the blood. Menflruation obeys the lunations. Queries. VII. ®hiiefcence of large glands a caufe ofi fever. Swelling of the pnecordia. VIII. Other caufes of quiefcence, as hunger, bad air, fear, anxiety. IX. I . Symp- toms of the cold fit. 2. Of the hot fit. 3. Second cold fit why. 4. Inflammation introduced, or delirium, or flupor. X. Recap- itulation. Fever not an effort of nature to relieve herfelf Doc- trine of fpafm. I. When the contractile fides of the heart and arteries per- form a greater number of pulfations in a given time, and move through a greater area at each pulfation, whether thefe motions are occafioned by the ftimulus of the acrimony or quantity of the blood, or by their affociation with other irritative motions, or by the increafed irritability of the arterial fyftem, that is, by an in- creafed quantity of fenforial power, one kind of fever is produ- ced ; which may be called Synocha irritativa, or Febris irritativa pulfu forti, or irritative fever with ftrong pulfe. When the contractile fides of the heart and arteries perform a greater number of pulfations in a given time, but move through a much lefs area at each pulfation, whether thefe motions are occafioned by defect of their natural ftimuli, or by the defect of other irritative motions with which they are aflcciated, or from the inirritability of the arterial fyftem, that is, from a decreafed quantity XXXII. 2. i. OF IRRITATION. . iS2: quantity of fenforial power, another kind of fever arifes-, which may be termed, Typhus irritativus, or Febris irritativa pulfu de- bili, or irritative fever with weak pulfe. The former of thefe fevers is the fynocha of nofologifts, and the latter the typhus mi- tior, or nervous fever. In the former there appears to be an increafe of fenforial power, in the latter a deficiency of it ; which is (hewn to be the immediate caufe of ftrength and weak- nefs, as defined in Se£t. XII. i. 3. It mould be added, that a temporary quantity of ftrength or debility may be induced by the defect or excefs of ftimulus above what is natural ; and that in the fame fever debility always exifls during the cold jit, though Jlrength does not always exijl during the hot fit. Thefe fevers are always connected with, and generally indu- ced by, the difordered irritative motions of the organs of fenfe, or of the inteftinal canal, or of the glandular fyftem, or of the abforbent fyftem ; and hence are always complicated with fome or many of thefe difordered motions, which are termed the fymp- toms of the fever, and which compofe the great variety in thefe difeafes. The irritative fevers both with ftrong and with weak pulfe, as well as the fenfitive fevers with ftrong and with weak pulfe, which are to be defcribed in the next fection, are liable to peri- odical remiflions, and then they take the name of intermittent fevers, and are diftinguifhed by the periodical times of their accefs. II. For the better illuftration of the phenomena of irritative fevers we mud refer the reader to the circumftances of irritation explained in Seel:. XII. and fhall commence this intricate fubjedc by fpeaking of the quick pulfe, and proceed by confidering many of the caufes, which either feparately or in combination molt frequently produce the cold fits of fevers. 1. If the arteries are dilated but to half their ufual diameters, though they contract twice as frequently in a given time, they will circulate only half their ufual quantity of blood : for as they are cylinders, the blood which they contain muft be as the fquares of their diameters. Hence when the pulfe hecomes- quicker and fmaller in the fame proportion, the heart and arte- ries act with lefs energy than in their natural ftate. See Sect. XII. 1. 4. That this quick fmall pulfe is owing to want of irritability, appears, firft, becaufe it attends other fymptoms of want of ir- ritability ; and, fecondly, becaufe on the application of a ftimu- lus greater than ufual, it becomes flower and larger. Thus in cold fits of agues, in hyfteric palpitations of the heart, and when the 284 DISEASES Sect. XXXII. 2. 2. the body is much exhaufted by haemorrhages, or by fatigue, as well as in nervous fevers, the pulfe becomes quick and fmall 5 and fecondly, in all thofe cafes if an increafe of flimulus be ad- ded, by giving a little wine or opium ; the quick fmall pulfe be- comes flower and larger, as any one may eafily experience on himfelf, by counting his pulfe after drinking one or two glafles of wine, when he is faint from hunger or fatigue. Now nothing can fo flrongly evince that this quick fmall pulfe is owing to defecl: of irritability, as that an additional ftimulus, abov« what is natural, makes it become flower and larger immediately : for what is meant by a defecl: of irritabili- ty, but that the arteries and heart are not excited into their ufual exertions by their ufual quantity of ftimulus ? but if you increafe the quantity of ftimulus, and they immediately act with their ufual energy, this proves their previous want of their natural de- gree of irritability. Thus the trembling hands of drunkards in a morning become fteady, and acquire ftrength to perform their ufual offices, by the accuftomed ftimulus of a glafs or two of brandy, 2. In fleep and in apoplexy the pulfe becomes flower, which Lo not owing to defecl of irritability, for it is at the fame time larger ; and thence the quantity of the circulation is rather in- creafed than diminifhed. In thefe cafes the .organs of fenfe are clofed, and the voluntary power is fufpended, while the motions dependent on internal irritations, as thofe of digeftion and fecre- tion, arc carried on with more than their ufual vigour •, which has led fuperficial obfervers to confound thefe cafes with thofe arifing from want of irritability. Thus if you lift up the eyelid of an apoplectic patient, who is not actually dying, the iris will, as ufual, contract, itfelf, as this motion is alfociated with the ftimulus of light ; but it is not fo in the laft ftages of ner- vous fevers, where the pupil of the eye continues expanded in the broad day-light : in the former cafe there is a want of volun- tary power, in the latter a want of irritability. Hence alfo thofe conftitutions which are deficient in quantity of irritability, and which pofiefs too great fenfibility, as during the pain of hunger, of hyiteric fpafms, or nervous headachs, are generally fuppofed to have too much irritability ; and opium, which in its due dole is a moft powerful ftimulant, is errone- ously called a fedative ; becaufe by increafing the irritative mo- ms it decreases the pains arifing from defect of them. Why the pulfe (hpuld become quicker both from an increafe F irritation, as in the fynocha irritativa, or irritative fever with ftrong pulfe ; and from the decreafe of it, as in the typhus irrita- U6, or irritative fever with weak pulfe ; feems paradoxical. The $ect. XXXII. 2. 3. OF IRRITATION. 28- The former circumftance needs no illuftration ; fince if the (limit- lus of the blood, or the irritability of the Sanguiferous fyftem be increased, and the ftrength of the patient not diminihed, it is plain that the .motions mud be performed quicker and ftronger. In the latter eircumflance the weakneis of the mufcular pow- er of the heart is fdon over-balanced by the elafticity of the coats of the arteries, which they poflefs befides a mufcular power of contraction ; and hence the arteries are diftended to lefs than their ufual diameters. The heart being thus flopped, when it is but half emptied, begins fooner to dilate again •, and the ar- teries being dilated to lek than their ufual diameters, begin h much fooner to contradt themfelves; infomuch, that in the laft ftages of fevers with weaknefs the frequency of pulfation of the heart and arteries become doubled ; which, however, is never the cafe in fevers with ftrength, in which they feldom exceed 118 or 120 pulfation s in a minute. It mult be added, that in thefe cafes, while the puife is very fmali and very quick, the heart often feels large, and labouring to one's hand \ which co- incides with the above explanation, (hewing that it does riot completely empty itfeif. 3. In cafes however of debility from paucity of blood, as in animals which are bleeding to death in the fiaughter-houfe, the quick pulfations of the heart and arteries may be owing to their not being diftended to more than half their ufual diaftole; and in confequence they mult contract fooner, or more frequently, in a given time. As weak people are Liable to a deficient quan- tity of blood, this caufe may occasionally contribute to quicken the pulfe in fevers with debility, which may be known by ap- plying one's hand upon the heart as above; but the principal caufe I fuppofe to confift in the diminution of fenforial power. When a mufcle contains, or is fupplied with but little fenforial power, its contraction foon ceafes, and in conefquence may foon recur, as is feen in the trembling hands of people weakened by age or by drunkenifefs. See Seel. XII. j. 4. XII. 3. 4. It may neverthelefs frequently happen, that both the deficiency of ftimuius, as where the quantity of blood is leflened (as de- scribed in No. 4. of this feclion), and the deficiency of fenforial power, as in thofe of the temperament'of inirritabilty, delcribed in Sect. XXXI. occur at the fame time j which will thus add to the quicknefs of the pulfe and to the danger of the difeafe. III. 1. A certain degree of heat is necellary to mufcular mo- tion, and is, in confequence, effential to life. This is obferved in thofe animals and infects which pafs the cold feafon in a tor- pid ftate, and which revive on being warmed by the fire. This riecefiary ftimuius of heat has two fources \ one from the fluid atmofphere iZ6 DISEASES Sect. XXXII. 3. 2. •stmcfphcre of heat, in which all things are immerfed, and the other from the internal combinations of the particles, which form the various fluids, which are produced in the extenfive fyftems of the glands. When either the external heat, which iurrounds us, or the internal production of it, becomes lefTened to a certain degree, the pain of cold is perceived. This pain of cold is experienced mod fenfibly by our teeth,, when ice is held in the mouth ; or by our whole fyftem after having been previouily accuflomed to much warmth. It is probable, that this pain does not arife from the mechanical or chemical effects of a deficiency of heat -, but that, like the or- gans of fenfe by which we perceive hunger and third, this fenfe of heat fuiFers pain, when the ftimulus of its objectis wanting to excite the irritative motions of the organ ; that is, when the fenforial power becomes too much accumulated in the quiefcent fibres. See Sect.. XII. 5.3. For as the periftaltic motions of the ftomach are lefTened, when the pain of hunger is great, fo the action of the cutaneous capillaries are lefTened during the pain of cold ; as appears by the palenefs of the fkin, as explain- ed in Sect. XIV. 6. on the production of ideas. The pain in the fmall of the back and forehead in the cold fits of the ague, in nervous hemicrania, and in hyfteric parox- yfms, when all the irritative motions are much impaired, feems to arife from this caufe ; the veffels of thefe membranes ■ muicles become torpid by their irritative affociations with other pasts of the body, and thence produce lefs of their accuftom* fecretions, and in confeqaence lefs heat is evolved, and they experience the pain of cold ; which coklnefs may often be felt by the hand applied upon the affected part. 2. The importance of a greater or lefs deduction of heat from the fyitem will be more eafy to comprehend, if v/c firlt ■ifider the great expenfe of fenforial power ufed in carrying on the vital motions j that is, which circulates, abforbs, fecretes, rates, and elaborates the whole mafs of fluids with unceafing afhduity. The fenforial , r# or fpirit of animation, ufed in giving perpetual and itrong motion to the heart, which over- ciatticity and vis tnerthe of the whole arterial fyftem ; next the expenfe of fenforial power in moving with great force and velocity the innumerable trunks and ramifications of the arterial fyftem ; the exnenfe of fenforial power in circulating' the whole mafs of blood through the long and intricate intor- tions of the very fine veflels, which compofe the glands anil capillaries ; then the expenfe of fenforial power in the exer- tions of the abforbent extremities of all the lacteals, and of all the lymphatics, winch open their mouths on the external fur- face Sect. XXXII. 3. 2. OF IRRITATION. 287 face of the (kin, and on the internal furfaces of every cell or interftice of the body ; then the expenfe of fenibrial power in the venous abforption, by which the blood is received from the capillary veffels, or glands, where the arterial power ceafes, and is drunk up, and returned to the heart 5 next the expenfe of fenforial power ufed by the mufcles of refpiration in their of- fice of perpetually expanding the bronchia, or air-veflels, of the lungs ; and laitly in the unceafmg periftaitic motions of the ftomach and whole fyftem of interlines, and in ail the fecre- tions of bile, gaftric juice, mucus, perfpirabie matter, and the various excretions from the fyftem. If we conhder the ceafe- lefs expenfe of fenforial power thus perpetually employed, it will appear to be much greater in a day than all the voluntary exertions of our mufcles and organs of fenle confume in a week ; and all this without any fenfible fatigue ! Now, if but apart of thefe vital motions are impeded, or totally flopped for but a (hort time, we gain an idea that there mud be a great ac- cumulation of fenforial power ; as its production in theie or- gans, which are fubjeft to perpetual activity, 13 continued dur- ing their quiefcence, and is in confequence accumulated. While, on the contrary, where thole vital organs aft too for- cibly by increafe of ftimulus without a propordonally-increaied production of fenforial power in the brain, it is evident, that a great deficiency of aftion, that is torpor, muft foon follow, as in fevers ; whereas the locomotive mufcles, which act only by intervals, are neither liable to fo great accumulation of fenforial power during their times of inactivity, nor to fo great an ex- hauftion of it during their times of action. Thus, on going into a very cold bath, fuppofe at 33 degrees' of heat on Fahrenheit's fcale, the action of the fubcutaneous capillaries, or glands, and of the mouths of the cutaneous ab- forbents is diminifhed, or ceafes for a time. Hence lefs or no blood paffes thefe capillaries, and palenefs fucceeds. But foon after emerging from the bath, a more floricl colour and a greater degree of heat are generated on the Ikin than was poilelicd be- fore immerfion -9 for the capillary glands, after this quiefcent ftate, occafioned by the want of ftimulus, become more irritable than ufual to their natural ftimuli, owing to the accumulation of fenforial power, and hence a greater quantity of blood is tranf- mitted through them, and a greater fecretion of perfpirablt; matter ; and, in confequence, a greater degree of heat fucceeds During the continuance in cold water the breath is cold, and the aft of refpiration quick and laborious ; which have gener- ally been afcribed to the obftruftion of the circulating fluid by a fpafm of the cutaneous vefTels, and by a canfequent accumu- lation £B8 DISEASES Sect. XXXII. 3. 3, lation of blood in the lungs, occafioned by the preflure as well as bv the boldnefs of the water. This is not a fatisfa&ory ac- count of this curious phenomenon, fince at this time the whole circulation is lefs, as appears from the fmallnefs of the pulfe and coldnefs of the breath ; which {hew that lefs blood palles through the lungs in a given time ; the fame laborious breathing immediately occurs when the palencfs of the fkin is produced by fear, where no external cold or preflure are applied. The minute veffels of the bronchia, through which the blood paffes from the arterial to the venal fyftem, and which corref- pond with the cutaneous capillaries, have frequently been ex- pofed to coid air, and become quiefcenl along with thofe of the ikin j and hence their motions are fo affociated together, that when one is affected either with quiefcence or exertion, the other fympathizes with it, according to the laws of irritative aflbciation. See Seel:. XXVII. I. on haemorrhages. Betides the quiefcence of the minute veffels of the lungs, there are many other fyftems of veffels which become torpid from their irritative affociations with thofe of the fkin, as the abforbents of the bladder and interlines ; whence an evacuation of pale urine occurs, when the naked fkin is expofed only to the coldnefs of the atmofphere j and fpr inkling the naked body with cold water is known to remove even pertinacious confti- pation of the bowels. From the quiefcence of fuch extenfive fyftems of veffels as the glands and capillaries of the fkin, and' the minute veffels of the lungs, with their various abforbent fe- ries of veffels, a great accumulation of fenforial powers is occa- fioned ; part of which is again expended in the increafed ex- ertion of all thefe veffels, with an univerfal glow of heat in con- fequence of this exertion, and the remainder of it adds vigour to both the vital and voluntary exertions of the whole day. If the activity of the fubcutaneous veffels, and of thofe with which their actions are affociated, was too great before cold im- merfion, as in the hot days of fummer, and by that means the fenforial power was previoufiy diminifhed, we fee the caufe why the cold bath gives fuch prefent ftrength •, namely, by flop- ping the .unneceffary activity of the fubcutaneous veffels, and thus preventing the too great exhaultion of fenforial power ; which, in metaphorical language, has been called bracing the fyflem : which is, however, a mechanical term, only applicable drums, or mufical ftrings : as on the contrary the word re- taxatiotiy when applied to living animal bodies, can only mean too iiii ail a quantity of ftimulus, or too fmall a quantity of fenforial power ; as explained in Sect. XII. I. 3, This experiment of cold bathing prefents us with a fimple fever- fit ; Sect. XXXII. 3. 4. OF IRRITATION. 289 fever-fit ; for the pulfe is weak, fmall, and quick during the cold immerfion , and becomes ftrong, full, and quick during the fubfequent glow of heat ; till in a few minutes thefe fymp- toms fubfide, and the temporary fever ceafes. In thofe constitutions where the degree of inirritability, or of debility, is greater than natural, the coldnefs and palenefs of the fkin with the quick and weak pulfe continue a long time after the patient leaves the bath ; and the fubfequent heat ap- proaches by unequal flu filings, and he feels himfelf difordered for many hours. Hence the bathing in a cold fpring of water, where the heat is but forty eight degrees on Fahrenheit's ther- mometer, much difagrees with thofe of weak or inirritable hab- its of body ; who pofiefs fo little fenforial power, that they cannot without injury bear to have it diminifhed even for a {hort time ; but who can neverthelefs bear the more temperate coldnefs of Buxton bath, which is about eighty degrees of heat, and which ftrengthens them, and makes them by habit lefs lia- ble to great quiefcence from fmall variations of cold °, and thence lefs liable to be diforderectby the unavoidable accidents of life. Hence it appears, why people of thefe inirritable conftitutions, which is another expreflion for fenforial deficiency, are often much injured by bathing in a cold fpring of water ; and why they mould continue but a very (hort time in baths, which are colder than their bodies ; and fhould gradually increafe both the degree of the coldnefs of the water, and the time of their continuance in it, if they would obtain falutary effects from coid immerfions. See Se£t. XII. 2. 1. On the other hand, in all cafes where the heat of the exter- nal furface of the body, or of the internal furface of the lungs, is greater than natural, the ufe of expofure to cool air may be deduced. In fever-fits attended with ftrength, that is with great quantity of fenforial power, it removes the additional ftim- ulus of heat from the Surfaces above mentioned, and thus pre- vents their excefs of ufelefs motion -, and -in fever-fits attended with debility, that is with a deficiency of the quantity of fenfo- rial power, it prevents the great and dangerous wafte of fenfo- rial power expended in the unnecefTary increafe of the actions of the glands and capillaries of the ikin and iungs. 4. In the fame manner, when any one is long expofed to very cold air, a quiefcence is produced of the cutaneous and pulmonary capillaries and abforbents, owing to the deficiency of their ufual llimulus of heat ; and this quiefcence of fo great a quantity of veffels affects, by irritative affociation, the whole abforbent and glandular fyftem, which becomes in a greater or lefs degree qutefcent, and a cold fit of fever is produced. Vol. I. O o If 296 DISEASES Sect. XXXII. 4. r. If the deficiency of the ftimulus of heat is very great, the qui- efcence becomes fo general as to exftinguifh life, as in thofe who are frozen to death. If the deficiency of heat be in lefs degree, but yet fo great as in fome meafure to diforder the fyftem, and mould occur the fucceeding day, it will induce a greater degree of quiefcence than before, from its acting in concurrence with the period of the diurnal circle of actions, explained in Seel. XXXVI. Hence from a fmall beginning a greater and greater degree of quief- cence may be induced, till a complete fever-fit is formed ; and which will continue to recur at the periods by which it was produced. See Seel. XVII. 3.6. If the degree of quiefcence occafioned by defect of the ftimu- lus of heat be very great, it will recur a fecondtime by a flight- er caufe, than that which firft induced it. If the caufe, which induces thefecond fit of quiefcence, recurs the fucceeding day, the quotidian fever is produced ; if not'till the alternate day, the tertian fever ; and if not till after feventy-two hours from the firft fit of quiefcence, the quartan fever is formed. This laft kind of fever recurs lefs frequently than the other, as it is a dif- eafe only of thofe of the temperament of afibciability, as men- tioned in Seel; XXXI.; for in other conftitutions the capability of forming a habit ceafes, before the new caufe of quiefcence is again applied, if that does not occur fooner than in feventy-two hours. And hence thofe fevers, whofe caufe is from cold air of the night or morning, are more liable to obferve the folar day in their periods ; while thofe from other caufes frequently obferve the lunar day in their periods, their paToxyfms returning near an hour later every day, as explained in Sect. XXXVI. IV. Another frequent caufe of the cold fits of fever is the defect of the ftimulus of diftention. The whole arterial fyftem would appear, by the experiments of Hai4er, to be irritable by no other ftimulus, and the motions of the heart and alimentary canal are certainly in fome meafure dependent on the fame caufe. See Sec~t. XIV. 7. Hence there can be no wonder, that the diminution of diftention ibould frequently induce the quief- cence, which conftitutes the beginning of fever-fits. Monfieur Lieutaud has judicioufly mentioned the deficiency of the quantity of blood amongft the caufes of difeafes, which he fays is frequently evident in difiections : fevers are hence brought on by great haemorrhages, diarrhoeas, or other evacua- tions ; or from the continued ule of diet, which contains but little nourifhment ; or from the exhauftion occafioned by vio- lent fatigue, or by thofe chronic difeafes in which the digeftion is Sect. XXXII. 5. i. OF IRRITATION. 291 is much impaired ; as where the ftomach has been long affected with the gout or fcirrhus ; or in the paralyfis of the liver, as de- fcribed in Sect. XXX. Hence a paroxyfm of gout is liable to recur on bleeding or purging ; as the torpor of fome vifcus, which precedes the inflammation of the foot, is thus induced by the want of the ftimulus of diftention. And hence the extremi- ties of the body, as the nofe and fingers, are more liable to be- come cold, when we have long abftained from food ; and hence the pulfe is increafed both in flrength and velocity above the natural ftandard after a full meal by the ftimulus of diftention. However, this ftimulus of diftention, like the ftimulus of heat above defcribed, though it contributes much to the due action not only of the heart, arteries, and alimentary canal, but feems neceflary to the proper fecretion of all the various glands ; yet perhaps it is not the fole caufe of any of thefe numerous mo- tions : for as the la£leals, cutaneous abforbents, and the various glands appear to be ftimulated into action by the peculiar pun- gency of the fluids they abforb, fo in the inteftinal canal the pungency of the digefting aliment, or the acrimony of the feces, feems to contribute, as well as their bulk, to promote the perif- taltic motions ; and in the arterial fyftem, the momentum of the particles of the circulating blood, and their acrimony, ftimulate the arteries, as well as the diftention occafioned by it. Where the pulfe is fmall this defect of diftention is prefent^ and con- tributes much to produce the febris irritativa pulfu debili, or ir- ritative fever with weak pulfe, called by modern writers nervous fever, as a predifponent caufe. See Sect. XII. 1. 4. Might not the transfufion of blood, fuppofe of four ounces daily from a ftrong man, or other healthful animal, as a (beep or an afs, be ufed in the early ftate of nervous or putrid fevers with great profpect of fuccefs ? V. The defect of the momentum of the particles of the circu- lating blood is another caufe of the quiefcence, with which the ■ cold fits of fever commence. This ftimulus of the momentum of the progreflive particles of the blood does not act over the whole body like thofe of heat and diftention above defcribed, but is confined to the arterial fyftem 5 and differs from the ftimulus of the diftention of the blood, as much as the vibra- tion of the air does from the currents of it. Thus are the dif- ferent organs of our bodies ftimulated by four different mechan- ic properties of the external world : the fenfe of touch by the preflure of folid bodies fo as to diftinguifh their figure ; the mufcular fyftem by the diftention, which they occafion ; the in- ternal furface of the arteries, by the momentum of their moving particles 5 and the auditory nerves, by the vibration of them : and 292 DISEASES Sect. XXXII. e. 2. and thefe four mechanic properties are as different from each other as the various chemical ones, which are adapted to the numerous glands, and to the other organs of fenfe. 2. The momentum of the progreflive particles of blood is compounded of their velocity and their quantity of matter: hence whntever circumflances diminifh either of thefe without propor- tionally increafing the other, and without fuperadding either of the general ftimuli of heat or diftention, will tend to produce a quiefccnce of the arterial fyftem, and from thence of all the other irritative motions, which are connected with it. Hence in all thofe conflitutions or difeafes where the blood contains a greater proportion of ferum, which is the lighted part of its compofition, the pulfations of the arteries are weaker, as in nervous fevers, chlorofis, and hyfleric complaints ; for in thefe cafes the momentum of the progreflive particles of blood is lefs ; and hence, where the denfer parts of its compofition abound, as the red part of it, or the coagulable lymph, the arterial pulfations are ftronger •, as in thofe of robuft health, and in inflammatory difeafes. That this flimulus of the momentum of the particles of the circulating fluid is of the greateft confequence to the arterial action, appears from the experiment of injecting air into the blood veflels, which feems to deflroy animal life from the want of this flimulus of momentum ; for the diftention of the arteries is not diminifhed by it, it poflefles no corrofive acrimony, and is lefs liable to repafs the valves than the blood itfelf ; fince air-valves in all machinery require much lefs accuracy of con- ftruclion than thofe which are oppofed to water. 3. One method of increafing the velocity of the blood, and in confequence the momentum of its particles, is by the exercife of the body, or by the friction of its furface •, fo, on the contra- ry, too great indolence contributes to decreafe this flimulus of the momentum of the particles of the circulating blood, and thus tends to induce quiefcence ; as is feen in hyiteric cafes, and chlorofis, and the other difeafes of fedentary people. 4. The velocity of the particles of the blood in certain cir- cumftances is increafed by venefeclion, which, by removing a part of it, diminifhes the refiflance to the motion of the other part, and hence the momentum of the particles of it is increaf- ed. This may be eafily underflood by confidering it in the ex- treme, fince, if the refiflance was greatly increafed, fo as to over- come the propelling power, there could be no velocity, and in confequence no momentum at all. From this circumftance arifes that curious phenomenon, the truth of which I have been >re than once witnefs to, that venefedion will often inflanta- neoufly Sect. XXXII. 6. i. OF IRRITATION. 793 neoufly relieve thofe nervous pains, which attend the cold peri- ods of hyfteric, afthmatic, or epileptic difeafes ; and that even where large dofes of opium have been in vain exhibited. In thefe cafes the pulfe becomes ftronger after the bleeding, and the extremities regain their natural warmth ; and an opiate then given acts with much more certain effect. VI. There is another caufe, which feems occafionally to in- duce quiefcence into fome part of our iyftem, I mean the influ- ence of the fun and moon -, the attraction of thefe luminaries, by decreafing the gravity of the particles of the blood, cannot af- fect their momentum, as their vis inertix remains the- fame ; but it may neverthelefs produce fome chemical change in them, becaufe whatever affects the general attractions of the particles •of matter may be fuppofed from analogy to affect their fpecific attractions or affinities : and thus the flimulus of the particles of blood may be diminiihed, though not their momentum. As the tides of the fea obey the fouthing and northing of the moon (allowing for the time neceffary for their motion, and the ob- ilructions of the fhores), it is probable, that there are alfo at- mofpheric tides on both fides of the earth, which to the inhab- itants of another planet might fo deflect the light as to refemble the ring of Saturn. Now as thefe tides of water, or of air, are raifed by the diminution of their gravity, it follows, that their preffure on the furface of the earth is no greater than the preffure of the other parts of the ocean, or of the atmofphere, where no fuch tides exift ; and therefore that thev cannot affect the mer- cury in the barometer. In the fame manner, the gravity of all other terreftrial bodies is diminiihed at the times of the fouth- ing and northing of the moon, and that in a greater degree when this coincides with the fouthing and northing of the fun, and this in a ftill greater degree about the times of the equinoxes. This decreafe of the gravity of all bodies during the time the moon paffes our zenith or nadir might poffibly be (hewn by the flower vibrations of a pendulum, compared1 with a fpring clock, or with aftronomical obfervation. Since a pendulum of a cer- tain length moves flower at the line than near the poles, becaufe the gravity being diminiihed and the vis inertia? continuing the fame, the motive power is lefs, but the refiftanceto be overcome continues the fame. The combined powers of the lunar and folar attraction are eftimated by Sir Ifaac Newton not to exceed one 7,868,850th part of the power of gravitation, which feems indeed but a fmall circumftance to produce any considerable ef- fect on the weight of fublunary bodies, and yet this is fufficient to raife the tides at the equator above ten feet high ; and if it be confidered, what fmall impulfes of other bodies produce their effects 294 DISEASES Sect. XXXII. 6. i. effects on the organs of fenfe adapted to the perception of them, as of vibration on the auditory nerves, we {hall ceafe to be fur- prifed, that fo minute a diminution in the gravity of the parti- cles of blood mould fo far affect their chemical changes, or their itimuhting quality, as, joined with other caufes, fometimes to produce the beginnings of difeafes. Add to this, that if the lunar influence produces a very fmall degree of quiefcence at firft, and if that recurs at certain peri- ods even with lefs power to produce quiefcence than at firft, yet the quiefcence will daily increafe by the acquired habit acting at the fame time, till at length fo great a degree of quiefcence is induced as to produce phrenfy, canine madnefs, epilepfy, hyfter- ic pains or cold fits of fever, inftances of many of which are to be found in Dr. Mead's work on this fubje£t. The folar influ- ence alfo appears daily in feveral difeafes •, but as darknefs, fi- lence, fleep, and our periodical meals mark the parts of the fo- lar circle of actions, it is fometimes dubious to which of thefe the periodical returns of thefe difeafes are to be afcribed. As far as I have been able to obferve, the periods of inflam- matory difeafes obferve the folar day ; as the gout and rheuma- tifm have their greatelt quiefcence about noon and midnight, and their exacerbations fome hours after ; as they have more frequently their immediate caufe from cold air, inanition, or fa- tigue, than from the effects of lunations : whilft the cold fits of hyfteric patients, and thofe in nervous fevers, more frequently occur twice a day, later by near half an hour each time, accord- ing to the lunar day ; whilft fome fits of intermittents, which are undifturbed by medicines, return at regular folar periods, and others at lunar ones •, which may, probably, be owing to the difference of the periods of thofe external circumftances of cold, inanition, or lunation, which immediately caufed them. We muft, however, obferve, that the periods of quiefcence and exacerbation in difeafes do not always commence at the times of the fyzygies or quadratures of the moon and fun, or at the times of their palling the zenith or nadir ; but as it is probable, that the flimulus of the particles of the circumfluent blood is gradually diminifiied from the time of the quadratures to that of the fyzygies, the quiefcence may commence at any hour, when co-operating with other caufes of quiefcence, it becomes great enough to produce a difeafe : afterwards it will continue to re- cur at the fame period of the lunar or folar influence ; the fame caufe operating conjointly with the acquired habit, that is with the catenation of this new motion with the diffevered links of the lunar or folar circles of animal adlion. In this manner the periods of menilruation obey the lunar month Sect. XXXII. 7. i. OF IRRITATION. 29 r month with great exaftnefs in healthy patients (and perhaps the venereal orgafm in brute animals does the fame), yet thefe pe- riods do not commence either at the fyzygies or quadratures of the lunations, but at whatever time of the lunar periods they be- gin, they obferve the fame in their returns till fome greater caufe difturbs them. Hence, though the belt way to calculate the time of the ex- pected returns of the paroxyfms of periodical difeafes is to count the number of hours between the commencement of the two preceding fits, yet the following obfervations may be worth at- tending to, when we endeavour to prevent the returns of maniac- al or epileptic difeafes ; whofe periods (at the beginning of them efpecially) frequently obferve the fyzygies of the moon and fun, and particularly about the equinox. The greateft of the two tides happening in every revolution of the moon, is that when the moon approaches neareft to the zenith or nadir; for this reafon, while the fun is in the northern figns, that is during the vernal and fummer months, the greater of the two diurnal tides in our latitude is that, when the moon is above the horizon ; and when the fun is in the fouthern figns, or during the autumnal and winter months, the greater tide is that, which arifes when the moon is below the horizon ; and as the fun approaches fome what nearer the earth in winter than in fummer, the greateft equinoctial tides are obferved to be a lit- tle before the vernal equinox, and a little after the autumnal one. Do not the cold periods of lunar difeafes commence a few hours before the fouthing of the moon during the vernal and fummer months, and before the northing of the moon during the autumnal and winter months ? Do not paifies and apoplex- ies, which occur about the equinoxes, happen a few days before the vernal equinoctial lunation, and after the autumnal one ? Are not the periods of thofe diurnal difeafes more obftinate, that commence many hours before the fouthing or northing of •the moon, than of thofe which commence at thofe times ? Are not thofe paifies and apoplexies more dangerous which com- mence many days before the fyzygies of the moon, than thofe which happen at thofe times ? See Sec~t. XXXVI. on the peri- ods of difeafes. VII. Another very frequent caufe of the cold fit of fever is the quiefcence of fome of thofe large congeries of glands, which compofe the liver, fpleen, or pancreas ; one or more of which are frequently fo enlarged in the autumnal intermittents as to be perceptible to the touch externally, and are called by the vul- gar ague-cakes. As thefe glands are ftimulated into action by the fpecific pungency of the fluids, which they abforb, the gener- al lg6 DISEASES Sect. XXXII. 8. «* al caufe of their quiefcence feems to be too great infipidity of the fluids of the body, co-operating perhaps at the fame time with other general caufes of quiefcence. Hence, in marfhy countries at cold feafons, which have fuc- ceeded hot ones, and amongft thofe, who have lived on innutri- tious and unftimulating diet, thefe agues are mod frequent. The enlargement of thefe quiefcent vifcera, and the fwelling of the pnecordia in many other fevers, is, molt probably, owing to the fame caufe j which may confift in a general deficiency of the production of fenlbrial power, as well as in the diminifned ftimulation of the fluids ; and when the quiefcence of fo great a number of glands, as conttitute one of thofe large vifcera, commences, all the other irritative motions are affected by their connexion with it, and the cold fit of fever is produced. VIII. There are many other caufes, which produce quiefcence of fome part of the animal fyftem, as fatigue, hunger, thirft, bad diet, difappointed love, unwholefome air, exhauftion from evacu- ations, and many others ; but the Lift caufe, that we ihall men- tion, as frequently productive of cold fits of fever, is fear or anxiety of mind. The pains, which we are firft and moft gen- erally acquainted with, have been produced by defect of fome ltimulus 5 thus, foon after our nativity we become acquainted with the pain from the coldnefs of the air, from the want of refpiration, and from the want of food. Now all thefe pains occafioned by defect of ftimulus are attended with quiefcence of the organ, and at the fame time with a greater or lefs degree of quiefcence of other parts of the fyftem : thus, if we even en- dure the pain of hunger fo as to mifs one meal inflead of our daily habit of repletion, not only the periftaltic motions of the ftomach and bowels are diminifhed, but we are more liable to coldnefs of our extremities, as of our nofes, and ears, and feet, than at other times. Now, as fear is originally excited by our having experienced pain, and is itfelf a painful affection, the fame quiefcence of other fibrous motions accompanies it, as has been moft frequent- ly connected with this kind of pain, as explained in Sect. XVI. 8. I. as the coldnefs and palenefs of the fkin, trembling, difficult refpiration, indigestion, and other fymptoms, which contribute to form the cold fit of fevers. Anxiety is fear continued through a Longer lime, and, by producing chronical torpor of the fyftem, extinguifh.es life Howly, by what is commonly termed a broken I rt. IX. i. V/e now ftep forwards to confider the other fymp- toms in confequence of the quiefcence which begins the fits of fever. If by any of the circumftances before defcribed, or by fw* Sect. XXXII. 9. 1. OF IRRITATION. 297 two or more of them acting at the fame time, a great degree of quiefcence is induced on any confiderabie part of the circle of irritative motions, the whole clafs of them is more or lefs dif- turbed by their irritative afibdations. If this torpor be occa- fioned by a deficient fupply of fenforial power, and happens to any of thole parts of the fyftem, which are accuftomed to per- petual activity, as the vital motions, the torpor increafes rapidly, becaufe of the great expenditure of fenforial power by the in- ceflant activity of thofe parts of the fyftem, as fhewn in No. 3, 2. of this Section. Hence a deficiency of all the fecretions fuc- ceeds, and as animal heat h produced in proportion to the quan- tity of thofe fecretions, the coldnefs of the fkin is the firft cir- cumftance, which is attended to. Dr. Martin aiTerts, that fome parts of his body were warmer than natural in the cold fit of fever ; but it is certain, that thofe, which are uncovered, as the fingers, and nofe, and ears, are much colder to the touch, and paler in appearance. It is poflibie, that his experiments were made at the beginning of the fubfequent hot fits ; which com- mence with partial diftributions of heat, owing to fome parts of the body regaining their natural irritability fooner than others. From the quiefcence of the anaftomofing capillaries a pale- nefs of the fkin fucceeds, and a lefs fecretion of the perfpirable matter ; from the quiefcence of the pulmonary capillaries a dif- ficulty of refpiration arifes •, and from the quiefcence of the oth- er glands lefs bile, lefs gaftric and pancreatic juice, are fecreted into the ftomach and interlines, and lefs mucus and faliva are poured into the mouth ; whence arifes the dry tongue, coftive- nefs, dry ulcers, and paucity of urine. fFrom the quiefcence of the abforbent fyftem arifes the great third, as lefs moifture is ab- sorbed from the atmofphere. The abforption from the atm'of- phere was obferved by Dr. Lifter to amount to eighteen ounces in one night, above what he had at the fame time infenfibly peu> fpired. See Langrifh. On the fame account the urine is pale* though in fmall quantity, for the thinner part is not abforbed from it •, and when repeated ague-fits continue long, the legs fwell from the diminimed abforption of the cellular abforbents. From the quiefcence of the inteftinal canal a lofs of appetite and flatulencies proceed. From the partial quiefcence of the glandular vifcera a fwelling and tenfion about the prsecordia be- come fenfible to the touch ; which are occafioned by the delay of the fluids from the defect of venous or lymphatic abforption. The pain of the forehead, and of the limbs, and of the fmall of the back, arifes from the quiefcence of the membranous fafcia, or mufcles of thofe parts, in the fame manner as the fkin be- comes painful, when the veiTels, of which it is compofed, be- Vol. I. P p come *9* DISEASES Sect. XXXII. 9. 4»- come ouicfceht from cold. The trembling in confequence of the pain of coldnefs, the reftleflhefs, and the yawning, and flrercning of the limbs, together with the fhuddering, or rigors, are convulfive motions ; and will be explained amongft the dif- eafes of volition \ Seel:. XXXIV. Sicknefs and vomiting are a frequent fymptom in the begin- nings of fever-fits, the mufcular fibres of the ftomach fhare the *neral torpor and debility of the fyftem ; their motions become firft leffened, and Hop, and then become retrograde; for the aft of vomiting, like the globus hyftericusandthe borborigmi of hvpo- chondriafis*, is always a fymptom of debility, either from want of fttmulus, as in hunger ; or from want of fenforial power, as af- ter intoxication ; or from fympathy with fome other torpid ir- ritative motions, as in the cold fits of ague. See Sect. XII. 5. 5. XXIX. 11. and XXXV. 1. 3. where this aft of vomiting is further explained. The fmall pulfe, which is faid by forne writers to be flow at the commencement of ague-fits, and which is frequently trem- bling and intermittent, is owing to the quiefcence of the heart and arterial fyftem, and to the refiftance oppofed to the circu- lating fluid from the inactivity of all the glands and capillaries.; The great weaknefs and inability to voluntary motions, with the irrfenfibility of the extremities, are owing to the general quief- cence of the whole moving fyftem ; or, perhaps, limply to the deficient produftioiKcf feniorial power. If ail thefe fymptom s are further increafed, the quiefcence of all (he mufcles, including the heart and arteries, becomes com- plete, and death enfues. This is, moft probably, the cafe of thoie who are ftarved to death with cold, and of thofe who are laid to die in Holland from long fkating on their frozen canals. 1. As foon as this general quiefcence of the fyftem ceafec, ( imer by the diminution of the caufe, or by the accumulation of 'ienforial power, (as in fyncope, Sect. XII. 7. 1.) which is the natural confequence of previous quiefcence, the hot fit com- mences. Every gland of the body is now ftimulatcd into ftronger action than is natural, as its irritability is increafed by ac^ lation of feniorial power during its lare quiefcence, a fu- perabun ; the fecretions is produced, and an incrcafe of heat in confc nee of the increafe of thefe fecretions. The ft:in becomes red, and the perfpiration great, owing to the in- f the capillaries during jhe hot part of the p ar- il, e fecr of perfpirable matter is perhaps greater during the hot fit than in the fweating fit which follows *, but ..bforption of it alio is greater, it does not ftand on the fkin in vifible drops : add to this, that the evaporation of it alfo is Sect. XXXII. 9. t. OF IRRITATION. 299 is greater, from the increafed heat of the fk'm. But at the de- cline of the hot fit, as the mouths of the abforbents of the fkin are expofed to the cooler air, or bed-clothes, thefe vefiels fooner lofe their increafed activity, and ceafe to abforb more than their natural quantity : but the fecerning vefTels for fome time longer, being kept warm by the circulating blood, continue to pour out an increafed quantity of perfpirable matter, which now (lands on the fkin in large vifible drops; the exhalation of it alio being leiTened by the greater coolnefs of the fkin,' as well as its abforp- tion by the diminifhed action of the lymphatics. See Cjafs L *• 2. 3. The increafed fecretion of bile and of Gther fluids poured in- to the interlines frequently induces a purging at the deeline of the hot fit ; for as the external abforbent vefTels have their mouths expofed to the cold air, as above mentioned, they ceafe to be excited into unnatural activity (boner than the fecretory VefTels, whole mouths are expofed to the warmth of the blood : •now, as the internal abforbents fympathize with the external ones, thefe alfo, which during the hot fit drank up the thinner part of the bile, or of other fecreted fluids, iofe their increafed activity before the gland lofes its increafed activity, at the de- cline of the hot fit; and the loofe dejections are produced from jfche fame caufe, that the increafed perfpiration (lands on the fur- face of the fkin, from the increafed abforpticn ceafing fooner than the increafed fecretion. The urine during the cold fit is in fmall quantity and pale, both from a deficiency of the fecretion and a deficiency of the abforption. During the hot fit it is in its ufuai quantity, but very high coloured and turbid, becaufe a greater quantity had been fecreted by the increafed action of the kidneys, and alfo a greater quantity of its more aqueous part had been abforbed froaa it in the bladder by the increafed action of the abforbents ; and laitly, at the decline of the hot fit it is in large quantity and left coloured, or turbid, becaufe the abforbent "VefTels of the bladder, as obferved above, lofe their increafed action by fympathy with the cutaneous ones fooner than the fecretory vefTels of the kid- neys lofe their increafed activity. Hence the quantity of the fedi- ment, and the colour of the urine, in fevers, depend much on the quantity fecreted by the kidneys, and the quantity abforbed from it again in the bladder : the kinds of fediment, as the lateritious, purulent, mucous, or bloody fediments, depend on other caufes. It mould be obferved, that if the fweating be increafed by the heat of the room, or of the bed-clothes, a paucity of turbid urine will continue to be produced, as the abforbents of the bladder will have their activity increafed by their fympathy with the vefTel? 3oo DISEASES Sect. XXXH. 9. 3. velTels of the fkin, for tliepurpofe of fupplying the fluid expend- ed in perfpi ration. The puife becomes ftrong and full, owing to the increafed Ir- ritability of the heart and arteries, from the accumulation of fen- forial power during their quiefeence, and to the quicknefs of the return of the blood from the various glands and capillaries. This increafed action of all the fecretory velTels dofes not occur very fuddenly, nor univerfally at the fame time. The heat feems to begin about the centre, and to be diffuied from thence irregu- larly to the other parts of the fyftem. This may be owing to the Situation of the parts which firft became quiefcent and caufed the fever-fit, efpecially when a hardnefs or tumour about the pneccrdia can be felt by the hand ; and hence this part, in whatever vifcus it is feated, might be the firft to regain its nat- ural or increafed irritability. 3. It mult be here noted, that, by the increafed quantity of heat, and of the impulfe of the blood at the commencement of the hot fit, a great increafe of itimulus is induced, and is now added to the increafed irritability of the fyftem, which was oc- cafioned by its previous quiefeence. This additional Ilimulus of heat and momentum of the blood augments the violence the movements of the arterial and glandular fyilem in an in- creafmg ratio. Thefe violent exertions (till producing more heat and greater momentum of the moving fluids, till at length the fenforial power becomes waited by this great itimulus be- neath its natural quantity, and predifpofes the fyftem to a fec- ond cold fit. At length all thefe unnatural exertions fpontaneoufly fubfide with the increafed irritability that produced them \ and which was itfelf produced by the preceding quiefeence, in the fame manner as the eye, on coming from datknefs into day-light, in a little time ceafes to be dazzled and pained, and gradually re- covers its natural degree of irritability. 4. But if the increafe of irritability, and the confequent in- creafe of the flimulus of heat and momentum, produce more violent exertions than thofe above defcribed > great pain arifrs in fome part of the moving fyftem, as in the membranes of the brain, pleura, or joints •, and new motions of the velTels are pro- duced in confequence of this pain, which are called inflamma- on ■, or delirium or Itupor arifes •, as explained in Seel:. XXI. and XXXIII. : for the immediate e (Feci: is the fame, whether the great energy of the moving organs arifes from an increafe of itimulus or an increafe of irritability \ though in the former czfc the wafte of fenforial power leads to debility, and in the latter %o health. Recapitulation* Sect. XXXII. 10. i. OF IRRITATION. ga* Recapitulation* X. Thofe mufcles, which are iefs frequently exerted, 2nd. whole actions are interrupted by fleep, acquire lefs accumulation of renfori?.i power during their quiefcent ftate, as the mufcles pi lc x>moiion. In thefe mufcles after great exertion, that is, after great exhaustion of the fenforial power, the pain of fatigue enfues3 and during reft there is a renovation of the natural amity of fenforial power ; but where the reft, or quiefcence •cf in fele, is long continued, a quantity' of fenforial power cumulated beyond what is neceffary ; as appears by rnefs occafioned by want of exercife ; and which in g animals is one caufe exciting them into action, as is feen in the play of puppies and kittens. But when thofe mufcles, which are habituated to perpetual actions, as thofe of the ftomach by the ftimulus of food, thofe of the veflels of the fkinby the ftimulus of heat, and thofe which conftitute the arteries and glands by the ftimulus of the blood, become for a time quiefcent, from the want of their appropria- ted ftimuli, or by their aflbciations with other quiefcent parts of the fyftem •, a greater accumulation of fenforial power is ac- quired during their quiefcence, and a greater or quicker ex- hauftion of it is produced during their increafed action. This accumulation of fenforial power from deficient action, if it happens to the ftomach from want of food, occafions the pain of hunger ; if it happens to the veflels of the fkin from want of heat, it occafions the pain cf cold ; and if to the arterial fyftem from the want of its adapted ftimuli, many difagreeable fenfations are occafioned, fuch as are experienced in the cold fits of intermittent fevers, and are as various, as there are glands or membranes in the fyftem, and are generally termed univerfal uneafinefs. When the quiefcence of the arterial fyftem is not owing to de- fect of ftimulus as above, but to the defective quantity of fenfo- rial power, as in the commencement of nervous fever, or irrita- tive fever with weak pulfe, a great torpor of this fyftem is quickly induced ; becaufe both the irritation from the ftimulus of the blood, and the aflbciation of the vafcular motions with each other, continue to excite the arteries into action, and thence quickly exhauft the ill-fupplied vafcular mufcles •, for to reft is death 5 and therefore thofe vafcular mufcles continue to pro- ceed, though with feebler action, to the extreme of wearinefs or faintnefs : while nothing iimiiar to this affects the locomo- tive mufcles, whofe actions are generally caufed by volition, and not 3o2 DISEASES Sect. XXXII. 10. \l not much fubject either to irritation or to other kinds of aiTo- ciations befides the voluntary ones, except indeed when they are excited by the lafh of ilavery. In thefe vafcular mufcles, which are fubject to perpetual ac- tion, and thence liable to great accumulation of fenforial power during their quielcence from want of fiimulus, a great increafc of activity occurs, either from the renewal of their accuftomed fiimulus, or even from much lefs quantities of fiimulus than ufu- al. This increafc of action conflitutes the hot hi of fever, • which is attended with variousjncreafed fecretions, with great concomitant hear, and general uneafinefs. The uneafinefs at- tending this hot paroxyfm of fever, or fit of exertion, is very dif- ferent from that, which attends the previous cold fit, or fit. of • quiefcence, and is frequently the caufe of inflammation, as in pleurify, which is treated of in the next fection. A fimilar effect, occurs after the quiefcence of our organs of fenfe ; thofe which are not fubjecl; to perpetual action, as the tafte and fmell, are lefs liable to an exuberant accumulation of fenforial power after their having for a time been inactive ; but the eye, which is in perpetual action during the day, becomes dazzled, and liable to inflammation after a temporary quiefcence. Where the previous quiefcence has been owing to a defect of fenforial power, and not to a defect of hamulus, as in the irrita- tive fever with weak pulfe, a fimilar increafe of activity of the arterial fyflem fucceeds, either from the ufual fiimulus of the blood, or from a fiimulus lefs than ufual ; but 36 there is general in thefe cafes of fever with weak pulfe a deficiency of the quantity of the blood, the pulfe in the hot fit is weaker than in health, though it is ftronger than in the cold fit, as explained in No. 2. of this fection. But at the fame time in thofe fevers, where the defect of irritation is owing to the defect of the quantity of fenforial power, as well as to the defect of fiimulus, another circumftance occurs ; which confifls in the partial dif- tributton of it, as appears in partial flufhings, as of the face or bofom, while the extremities are cold ; and in the increafe of particular fecretions, as of bile, faliva, infenfible perfpiration, with gre^t heat of the fkin, or with partial fweats, or diarrhoea. There are alfo many uneafy fenfations attending thefe in- creafed actions, which like thofe belonging to the hot fit of fe- ver with itrong pulfe, are frequently followed by inflammation, ■ as in fearlet fever j which inflammation is neverthelefs accom- panied with a pulfe weaker, though quicker, than the pulfe du- 2 remiffion or intermiffion of the paroxyfms, though ilronger than that of the previous cold fit. From hence I conclude, that both the cold and hot fits of fe- ver Sect. XXXII. n. u OF IRRITATION. 303 ver are neceiTary confequences of the perpetual and inceffanE action of the arterial and glandular fyilem ; fince thole mufcu- lar fibres and thofe organs of fenie, which are moil frequently exerted, become neceffariiy mod affected both with defect and accumulation of fenforial power : and that hence fever-fits are not an effort of nature to relieve her/elf and that therefore they fhould always be prevented or diminiihed as much as pofiible, by any means which decreafe the general or partial vafcular ac- tions, when they are greater, or by increafing them when they are lefs than in health, as defcribed in Seel. XII. 6. 1. Thus have I endeavoured to explain, and I hope to the fatis- faction of the candid and patient reader, the principal fymp- tcms or circumftances of fever without the introduction of the iupernatural power of fpafm. To the arguments in favour of the doctrine of fpafm it may be fufheient to reply, that in the evolution of medical as well as of dramatic catailrophe, Nee Deus interfit, nifi dignus vindice nodus Incident. Hor. XI. i. Since I printed the above in the firit edition of this work, I am told, that the fpafmodic doctrine of fever has yet its • advocates ; who believe that the coidnefs at the beginning of in- termittent fevers is owing to a fpafm of the cutaneous verTels. But as the ikin is at that time lax and foft, the mufcular fibres of thofe cutaneous vefTels cannot be in action or contraction, which conflitute fpafm. Whence we have the evidence both of our fight and touch againft this wild imagination. Others have advanced, that this fpafmodic contraction of the cutaneous vefTels or pores confines the heat, or drives it to the heart ; which in the hot fit of fever repels the heat again to the Ikin by its reaction. Thofe, who efpoufe this doctrine, feem to conceive, that the particles of heat are as large as (hot-corns, or as the globules of blood ; and not that it is an ethereal fluid, in which all things are immerfed, and by which all things are penetrated ; an opinion which originated from Galen, and muft have been founded on a total ignorance of chemiftry, and natu- ral philofophy. Others, I hear, ftiii fuppofe coid to be a ftima- lus, not underftanding that it is fimply the abfence of heat ; and that darknefs might as well be called a ilimulus to the eye, or hunger a (limulus to the ftomach, as cold to our {en[c, which perceives heat ; which is commonly confounded with our fenie of touch, which perceives figure. The pain, which we experi- ence on being expofed to a want of heat, which is termed chill- aefs, or coidnefs \ and the pain we experience in our organs of digeftkm 304 DISEASES Sect. XXXII. i r. i. digeftion from the want of food, which is termed hunger ; both arife from the inactivity of thole vefTels, which ought to be either perpetually, or at periodical times itimulated into action. See Seel:. XIII. 3. 2. And the fhivering or actions of the fubcuta- neous mufcles, when we are cold, are in confluence of the pain, or voluntary exertion to relieve that pain, and originate from the want of ftimulus, not from the excefs of it. In this age of reafon it is not the opinions of others, but the natural phenomena, on which thofe opinions arc founded, which deferve to be canvafTed. And with the fuppofed exig- ence of ghofts or apparitions, witchcraft, vampyrifm, aftrology, animal magnetifm, and American tractors, fuch theories as the above muft vanifh like the fcenery of a dream •, as they con fid of fuch combinations of ideas, as have no prototype or corres- pondent combinations of material objects exifting in nature. SECT. Sect. XXXIH. i. i. OF SENSATION. 305 SECT. XXXIIL DISEASES OF SENSATION. I. 1. Motions excited by fenfation. Digeflion. Generation. Pleaf ure of exigence. Hypochondriacifm. 2. Pain introduced. fen- fitive fevers of two kinds. [13. Two fenforia I powers exerted in fenfitive fevers. Size of the blood. Nervous fevers diflinguifhed from putrid ones. The feptic and antifeptic theory. 4. Two kinds of delirium. 5. Other animals are lefs liable to delirium , cannot receive our contagious difeafes, and are lefs liable to madnefs. II. 1. Sen/it ive motions generated. 2. Inflammation explained. 3. Its remote caufes from excefs of irritation , or of 'irritability •, not from thofe pains which are owing to defecl of irritation. New vef- fels produced, and much heat. 4. Purulent matter fecreted. 5. Con- tagien explained. 6. Received but once. *]. If common matter be contagious ? 8. Why fame contagions are received but once. 9. Why others may be received frequently. Contagions of fm all-pox and meafes do not atl at the fame time. Two cafes of fuch pa- tients. 10. The blood from patients in the fmall-pox will not in- feci others. Cafes of children thus inoculated. The variolous con- tagion is not received into the blood. It acJs by fenfitive afjbciation between the flomach andfhin. III. 1. Abforption of folids and fluids. 2. Art of healing ulcers. 3. Mortification' attended with lefs pain in weak people. I. 1. As many motions of the body are excited and continu- ed by irritations, fo others require, either conjunctly with thefe, or feparately, the pleafurable or painful fenfations, for the pur- pofe of producing them with due energy. Amongft thefe the bufinefs of digeftion fupplies us with an initance : if the food, which we fwallow, is not attended with agreeable fenfation, it digefts lefs perfectly ; and if very difagreeable fenfation accom- panies it* fuch as a naufeous idea, or very difguftful tafte, the digeftion becomes impeded •, or retrograde motions of the ftom- ach and cefophagus fucceed, and the food is ejected. The bufinefs of generation depends fo much on agreeable fen- fation, that, where the object, is difguftful, neither voluntary ex- ertion nor irritation can effect: the purpofe ; which is alfo liable to be interrupted by the pain of fear or baftvfulnefs. Befides the pleafure, which attends the irritations produced by the objects of luft and hunger, there feems to be a fum of pleaf- urable affection accompanying the various fecretions of the nu- merous glands, which conftitute the pleafure of life, in ccntrcdif- Vol. J. O 7 the increafed abforption of the in- flamed lym. I The Sect. XXXIII. i. 4. OF SENSATION. 307 The fenfitive fevers with weak pulfe, which are termed putrid or malignant fevers, are diftinguilhed from irritative fevers with weak pulfe, called nervous fevers, defcribed in the laft fection, as the former confift of inflammation joined with debility, and the latter of debility alone. Hence there is greater heat and more florid colour of the fkin in the former, with petechia?, or purple fpots, and aphthse, or Houghs in the throat, and generally with previous contagion. When animal matter dies, as a Hough in the throat, or the mortified part of a carbuncle, if it be kept moift and warm, a during its adhefion to a living body, it will, foon putrefy. This and the origin of contagion from putrid animal fubflances, feem to have given rife to the feptic and antifeptic theory of thefe fevers. The matter in puftules and ulcers is thus liable to become putrid, and to produce microfcopic animalcula -} the urine, if too long retained, may alfogain a putrescent fmell, as well as the alvine feces ; but fome writers have gone fo far as to believe, that the blood itfelf in thefe fevers has fmelt putrid, when drawu from the arm of the patient ; but this feems not well founded ; fmce a fingle particle of putrid matter taken into the blood can produce fever, how can we conceive that the whole mafs could continue a minute in a putrid ftate without deftroying life ? Add to this, that putrid animal fubftances give up air, as in gangrenes j and that hence if the blood was putrid, air fliould be given out, which in the blood-veiTels is known .to occafiorj immediate death. In thefe fenfitive fevers with flrong pulfe (or inflammations) there are two fenforial faculties concerned in producing the dif- eafe, viz. irritation and fenfation ; and hence, as their combined action is more violent, the general quantity of fenforial power becomes further exhaufted during the exacerbation, and the fyftem more rapidly weakened than in irritative fever with (trong pulfe ; where the fpirit of animation is weakened by but one mode of its exertion : fo that this febris fenutiva pulfu forti (or inflammatory fever) may be considered as the febris irritativa pulfu forti, with the addition of inflammation j and the febris fenfitiva pulfu debili (or malignant fever) may be confidered as the febris irritativa pulfu debili (or nervous fever, with the addi- tion of inflammation. 4. In thefe putrid or malignant fevers a deficiency of irrita- bility accompanies the increale of fenfibiiity ; and by this wafte of fenforial power by the, excefs of fenfation, which was already •too fmall, arifes the delirium and ftupor which fo perpetually at- tend thefe inflammatory fevers with arterial debility. In thefe afes the voluntary power firft ceafes to acl: from deficiency of fenforial 308 DISEASES Sect. XXXIII. 4. 4, fenforial fpirit; and the ftimuli from external bodies have no effecl: on the exhaufted fenforial power, and a delirium like a dream is the confequence. At length the internal ftimuli ceafe to excite fufficient irritation, and the fecretions are either not produced at all, or too parfimonious in quantity. Amongfl thefe the fecre- tion of the brain, or production of the fenforial power, becomes deficient, till at laft all fenforial power ceafes, except what is juft necefTary to perform the vital motions, and a ftupor fucceeds ; which is thus owing to the fame caufe as the preceding delirium exerted in a greater degree. This kind of delirium is owing to a fufpenfion of volition, and to the dilbbedience of the fenfes to external ftimuli, and is always occafioned by great debility, Or paucity of fenforial power ; it is therefore a bad fign at the end of inflammatory fevers, which had previous arterial ftrength, as rheumatifm, or pleurify, as it fhews the prefence of great exhauftion of fenforial power in a fyftem, which having lately been expofed to great excitement, is not fo liable to be ftimulated into its healthy aclion, either by additional ftimulus of food and medicines, or by the accumula- tion of fenforial power during its prefent torpor. In inflamma- tory fevers with debility, as thofe termed putrid fevers, deliri- um is fometimes, as well as ftupor, rather a favourable fign ; as lefs fenforial power is wafted during its continuance (fee Clafs II. 1. 6. 8.)> and the conftitution not having been previoufly ex- pofed to excefs of ftimuhtion, is more liable to be excited after previous qubicence. When the fum of general pleafurable fenfation becomes top great, another kind of delirium fupervenes, and the ideas thus excited are miftaken for the irritations of external objecls : fuch a delirium is produced for a time by intoxicating drugs, as fer- mented liquors, or opium : a permanent delirium of this kind is fometimes induced by the pleafures of inordinate vanity, or by the enthufiaftic hopes of heaven. In thefe cafes the power of volition is incapable of exertion, and in a great degree the exter- nal fenfes become incapable of perceiving their adapted ftimuli, becaufe the whole fenforial power is employed or expended on the ideas excited by pleafurable fenfation. This kind of delirium is diftinguifhed from that which at- tends the fevers above mentioned from its not being accompani- ed with general debility, but fimply with excefs of pleafurable fenfation ; and is therefore ;n fome mcafure allied to madnefs or to reverie ; it differs from the delirium of dreams, as in this the power of volition is not totally fufpended, nor are the fenfes precluded from external ftimulation $ there is therefore a degree of confiftency, in this kind of delirium, and a degree df attention to fikcT. XXXIII. i, $. OF SENSATION. 30$ to external objects, neither of which exifts in the delirium of levers or in dreams. 5. It would appear, that the vafcular fyftems of other animals are left liable to be put into action by their general furn of pleafurable or painful fenfation ; and that the trains of their ideas, and the mufcular motions ufualiy aflbciated with them, are lets powerfully connected than in the human fyftem. For other animals neither weep, nor fmile, nor laugh ; and are hence feldom iubiecl to delirium, as treated of in Sect. XVI. on Inftin£r. Now as cur epidemic and contagious diieaies arc probably produced by difagreeable fenfation, and not {imply by irritation ; there appears a reafon why brute animals are icis liable to epidemic or contagious difeafes ; andfecondly, why none of our contagions, as the.fmall-pox or meafles, can be com- municated to them, though one of theirs, viz. the hydrophobia, •as well as many of their poifons, as thofe of makes and of in- fects, communicate their deleterous or painful effects to mankind. Where the quantity of general painful fenfation is too great in the fyftem, inordinate voluntary exertions are produced either of our ideas, as in melancholy and madnefs, or of our mufci^ as in convulfion. From theie maladies alio brute animals are much more exempt than mankind, owing to their greater inapti- tude to voluntary exertion, as mentionedin Sect. XVI. onLifdnct. II. 1. When any moving organ is excited into fuch violent motions, that a quantity of pleafurable or painful fenfation is produced, it frequently happens (but not always) that new mo- tions of the affected organ are generated in confequence of the pain or pleafure, which are termed inflammation. Thefe new motions are of a peculiar kind, tending to diftend the old, and to produce new fibres, and thence to elongate the ftraight mufcles, which ferve locomotion, and to form new vef- fels at the extremities or fides of the vafcular mufcles. 2. Thus the pleafurable fenfations produce an enlargement of the nipples of nurfes, of the papilke of the tongue, of the peni>j and probably produce the growth of the body from its embryon ftate to its maturity •, whilft the new motions in confequence of painful fenfation, with the growth of the fibres or vellels, which they occafion, are termed inflammation. Hence when the ftraight mufcles are inflamed, part of their tendons at each extremity gain new life and fenfibility, and thus the mufcle is for a time elongated ; and inflamed bones become foft, vafcular, and fenfible. Thus new veiTels fhoot over the ■cornea of inflamed eyes, and into fcirrhous tumours, when thev become inflamed ; and hence all inflamed parts grow together Iby intermixture, and inoculation of the new and old veflel;. The 3 1 o DISEASES Sect. XXXIII. 2.3, The heat Is occaficned from the increafed fecretions either of mucus, or of the fibres, which produce or elongate the vefTels. The red colour is owing to the pellucidity of the newly formed veflels, and as the arterial parts of them arc probably formed be- fore their correfpondent venous parts. 3. Thefe new motions are excited either from the increafed quantity of fenfation in confequemce of greater fibrous contrac- tions, or from increafed fenfibility, that is, from the increafed quantity of fenforial power in the moving organ. Hence thev are induced by great external ftimuli, as by wounds, broken bones ; and by acrid or infectious materials ; or t>y common ftimuli on thofe organs, which have been fome time quiefcent ; 23 the ufual light cf the day inflames the eyes of thofe, who have been confined in dungeons ; and the warmth of a common fire inflames thole, who have been previoufly expofed to much cold. But thefe new motions are never generated by that pain, which arifes from deieel; of Hamulus, as from hunger, thirds cold, or inanition, with all thofe pains, which are termed ner- vous Where thefe pains exift, the motions of the affected part are leflened ; and if inflammation fucceeds, it is in fome diftant oarts ; as coughs are caufed by coldnefs and moiflure being long applied to the fcti •, or it is in eonfequence of the renewal of the ftimulus, as of heat or food, which excites our organs into stronger action after their temporary quiefeence j as kibed heels after walking in fnow. * 4. But when thefe new motions of the vafcular mufcles are exerted with greater violence, and thefe veflels are either elon^ ted too much cr ;, new material is fecreted from their extremities, which is of various kinds according to the peculiar animal motions of this new kind of gland, which fecretes it ; fuch is the- pus Iuudabile or common matter, the variolous mat- ter, venereal matter, catarrhous matter, and many others. 5. Thefe matters are the product of an animal procefs ; they are fecreted or produced from the blood by certain difeafed mo- tions of the extremities of the blood-vefTels, and are on that ac- inic all of them contagious ; for if a portion of any of thefe is tranfrnitted into the circulation, or perhaps only inferted into she fcin, or beneath the cuticle of a healthy perfon, its ftimulufl in a cer:a-;n t reduces the fame kind of morbid motions, by which iricic was produced :, and hence a (imilar kind is genera- ted. Sec Sea. xxxix. & 1. 6. lr 'varkabk., that many of thefe contagious ma ire capable of producing a fimUsi difeafe but once ; as the fmalli p^x and no | } fuppofe this is true of all thofe conta- b are aneoutly cured by nature in a cc taiu Sect. XXXIII. 2. 7. OF SENSATION. . pt tain time ; for if the body was capable of receiving the difeafe a fecond time, the patient mud perpetually infect himfelf by the very matter, which he has himfelf produced, and is lodged about him ; and hence he could never become free from the difeafc. Something fimilar to this is ken in the fecondary fever oi the confluent fmall-pox ; there is a great abforption of variolous matter, a very minute part of which would give the genuine fmall-pox to another perfon ; but here it only Simulates the fyftem into common fever ; like that which common pus, or any other acrid material might cccafion. 7. In the pulmonary confumption, where common matter is daily abforbed, an irritative fever only, without new inflam- mation, is generally produced ; which is terminated like other irritative fevers by fweats or loofe (tools. Hence it does not appear, that this abforbed matter always acts as a contagious ma- terial producing freih inflammation or new abfceffes. Though there is reafon to believe, that the firft time any common matter is abforbed, it has this effect, but not the fecond time, like the variolous matter above mentioned. This accounts for the opinion, that the pulmonary confump- tion is fometimes infectious, which opinion was held by the an- cients, and continues in Italy at prefent -, and I have myfelf ken three or four instances, where a hufband and wife, who have flept together, and have thus much received each other's breath* who have infected each other, and both died in confequence of the original taint of only one of them. This alfo accounts for the abfcelfes in various parts of the body, that are fometimes produced after the inoculated fmall-pox is terminated ; for thi* fecond abforption of variolous matter acts like common matterT and produces only irritative fever in thofe children, whofe conlti- tutions have already experienced the abforption of common mat- ter •, and inflammation with a tendency to produce new abfeeffes in thole, whofe conftitutions have not experienced the abforp- tions of common matter. It is probable, that more certain proofs might have been found to (hew, that common matter is infectious the firft time it i abforbed, tending to produce fimilar abfeeffes, but not the fec- ond time of its abforption, if this fubject had been attended fa. 8. Thefe contagious difeafes are very numerous, as t plague, fmall-pox, chicken pox, mealies, fcarlet-fever, ne- gus, catarrh, chin-cough, venereal difeafe, itch, trichoma, tinea- The infectious material does not feem to be diffolved by the ai.rr but only mixed with it perhaps in fine powder, which foon fubr fides ; fince many of thefe contagions can only be received by actual contact \ and others of them only at fmall diftances fro 31 a DISEASES Sect. XXXIK. 2. 9. the infected perfon ; as is evident from many perfons having been near patients of the fmall-pox without acquiring the difeafe. The reafon.whv many of thefe difeafes are received but once, a-nd others repeatedly, is not well understood ; it appears to me, that the constitution becomes fo accuitomed to the Stimuli of thefe infectious materials, by having once experienced them, that though irritative motions, as hectic fevers, may again be produced by them, yet no fen Cation, and in confequence no general inflammation fucceeds ; as difagreeable fmells or tafr.es f>y habit ceafe to be perceived •, they continue indeed to excite irritative ideas on the organs of fenfe, but thefe are not Succeed- ed by feniation. There are many irritative motions, which were at firSt fuc- ceeded by fenfation, but which by frequent repetition ceafe to ex- cite fenfation, as explained in Seel:. XX. on Vertigo. And, that this c ircum (lance exifts in refpect to infectious matter appears from a k:io\vn fact \ that nurfes, who have had the fmall-poxr are liable to experience fmall ulcers on their arms by the contact of variolous matter in lifting their patients; and that when pa- tterns, who have formeily had the fmall-pox have been inocula- ted in the arm, a phlegmon, or inflamed fore, has fucceeded, but no fubfequent fever. Which (hews, that the contagious matter of the fmall-pox has not loft its power of Stimulating the part it. feapplied to, but that the general fvftem is not affected in con- fequence. See Section XII. 7.6. XIX. 10. o. From the accounts of the plague, virulent catarrh, and putrid dyiVntery, it feems uncertain, whether thefe difeafes are experienced more than once ; but the venereal difeafe and itch arc doublets repeatedly infectious ; and as thefe difeafes ar * never cured fpontaneoufly, but require medicines, which act ithout apparent operation, feme have fufpected, that the con- gious material produces fimilar matter rather by a chemical ei of the fluids, than by ah animal procefs; and that the fpecif- edicines deftroy their virus by chemically combining with it. Ti inion is fuecefsfiilly combated by Mr. Hunter, in his Treat ' 1 Venereal Difeafe, Part I. c. i. But riii-s opinion wants the fupport of analogy, as there is no fen in animal bodies, which is purely chemical, not trend ion ; nor c;m any of thefe matters be produced by Bfoical pi >cefl I to this, that it is probable, that the infectr>. ot in the puftuies of the itch, .ind in the ftoolsof and at the fame time much heat is evolved from thefe combina- tions. By the rupture of thefe verTels, or by a new conftruction of their apertures, purulent matters are fecreted of various kinds ; which are infectious the firlt time they are applied to the fkin beneath the cuticle, or fwallowed with the faliva into the ftom- ach. This contagion acts not by its being abforbed into the circulation, but by the fympathies, or aflbciated actions, between the part firft ftimulated by the contagious matter and the other parts of the fyftem. Thus in the natural fmall-pox the conta- gion is fwallowed with the faliva, and by its ftimulus inflames the ftomach ; this variolous inflammation of the itomach increafes every day, like the circle round the puncture of an inoculated arm, till it becomes great enough to diforder the circles of irrita- tive and fenfitive motions, and thus produces fever-fits, with ficknefs and vomiting. Laftly, after the cold paroxyfm, or fit of torpor, of fche ftomach has increafed for two or three fuccef- five days, an inflammation of the fkin commences in points *, which generally firft appear upon the face, as the aflbciated ac- tions between the fkin of the face and that of the ftomach have been more frequently exerted together than thofe of any other parts of the external furface. Contagious matters, as thofe of the meafles and fmall-pox, do not act upon the fyftem at the fame time ; but the progrefs of that which was laft received is delayed, till the action of the for- mer infection ceafes. All kinds of matter, even that from com- mon, ulcers, are probably contagious the firft time they arc in- ferted Sect. XXXIII. 4. i. OF SENSATION. 323 ferted beneath the cuticle or fwallowed into the ftomach ; that is, as they were formed by certain morbid actions of the ex- tremities of the veflels, they have the power to excite fimilar morbid actions in the extremities of other veflels, to which they are applied ; and thefe by fympathy, or aflbciations of motion^ excite fimilar morbid actions in diftant parts of the fyftem, with- out entering the circulation ; and hence the blood of a patient in the fmall-pox will not give that difeafe by inoculation to others. When the new fibres or veflels become again abforbed into •the circulation, the inflammation ceafes ; which is promoted, after fufficient evacuations, by external ftimulants and bandages : but where the action of the veflels is very great, a mortification of the part is liable to enfue, owing to the exhauftion of fenfori- al power ; which however occurs in weak people without much pain, and without very violent previous inflammation ; and, like partial paralyfis, may be efteemed one mode of natural death of old people, a part dying before the whole. SECT. 324 DISEASES Sect. XXXIV. i. f. SECT. XXXIV. DISEASES OF VOLITION. I. I . Volition defined. Motions termed involuntary are caufed by volition. Defires oppofed to each other. Deliberation. Afs be-> tiveen two hay-cocks. Saliva /wallowed againfi one's defire. Voluntary motions dijlinguijhed from thofe ajfociated with fenfttive motions. 2. Pains from excefs, and from defetl of motion. No pain is felt during vehement voluntary exertion ; as in cold fits of ague, labour-pains ,' fir angury, tenefmus, vomiting, refllejfnefs in fevers, convulfion of a wounded mufcle. 3. Of holding the breath andfcreaming in pain ,- why fwine and dogs cry out in pain, and not fiheep and horfes. Of grinning and biting in pain ; why mad animals bite others. 4. Epileptic convulfions explained, why the fits begin with quivering of the under jaw, biting the tongue, and fitting the teeth ; why the convulfive motions are alternately relax- ed. The phenomenon of laughter explained. Why children can- not tickle themfelves. How fome have died from immoderate laughter. 5. Of cataleptic fpafms, of the locked jaw, of painful cramps. 6. Syncope explained. Why no external objects are perceived in fyncope. 7. Of palfy and apoplexy from violent exer- tions. Cafe of Mrs. Scot. From dancing, fcating, fwitnming. Cafe of Mr. Nairne. Why palfies are not always immediately preceded by violent exertions. P^lfy and epilepfy from difeafed livers. Why the right arm mote frequently paralytic than the left. How paralytic limbs regain their motions. II. Difeafes of the fenfual motions from excefs or defetl of voluntary exertion. I. Madnefs. 2. Difiinguifhed from delirium 3. Why man- kind more liable to infanity than brutes. Sufpicion. Want of Jhame, and of cleanlinefs. 5. They bear cold, hunger, and fa tigut. Charles XII. of Sweden. 6. Pleafurable delirium, and infinity. Child riding on a flick. Pains of martyrdom not felt. 7. Drop- fy. 8. Inflammation cured by infanity. III. 1. Pain relieved by reverie. Reverie is an exertion of voluntary and fenfttive mo- tions. 2. Cafe of reverie. 3. Lady fuppo fed to have two fouls. 4. Methods of relieving pain. I. 1. Before we commence this Section en Difeafed Volt untary Motions, it maybe neceflary to premife, that the word volition is not ufed in this work exactly in its common accepta- tion. Volition is faid in Seftion V. to bear the faii^e analogy to defire and averfion, which fenfution does to pleafure and pain. And hence that, when defire or averfion produces any adtion of the Sect. XXXIV. i. i. OF VOLITION. 325 the mufcular fibres, or of the organs of fenfe, it is termed voli- tion ; and the actions produced in confequence are termed vol- untary actions. Whence it appears, that motions of our muf- cles or ideas may be produced in confequence of defire or aver- fion without our having the power £0 prevent them, and yet thefe motions may be termed voluntary, according to our definition of the word ; though in common language they would be called involuntary. The objects of defire and averfion are generally at a diftance, whereas thofe of pleafure and pain are immediately acting upon our organs. Hence, before defire or averfion is exerted, fo as to caufe any actions, there is generally time for deliberation ; which confilts in difcovering the means to obtain the object of delire, or to avoid the object of averfion ; or in examining the good or bad confequences, which may refult from them. In this cafe it is evident, that we have a power to delay the pro- pofed action, or to perform it ; and this power of choofing, whether we (hall act or not, is in common language exprefled by the word volition, or will. Whereas in this work the word volition means fimply the active date of the fenforial faculty in producing motion in confequence of defire or averfion : whether we have the power of retraining that action, or not •, that is, whether we exert any actions in confequence of oppoiite defires or averfions or not. For if the objects of defire or averfion are prefent, there is no neceffity to inveftigate or compare the means of obtaining them, nor do we always deliberate about their confequences ; that is, no deliberation neceflarily intervenes, and in confequence the power of choofing to act or not is not exerted. It is probable, that this two-fold ufe of the word volition in all languages has confounded the metaphyficians, who have difputed about free will and neceflity. Whereas from the above analyfis it would appear, that during our fleep, we ufe no voluntary exertions at all ; and in our waking hours, that they are the confequence of defire or averfion. To will is to act in confequence of defire •, but to defire means to defire fomething, even if that fomething be only to be- come free from the pain, which caufes the defire ; for to defire nothing is not to defire ; the word defire, therefore, includes both the action and the object or motive *, for the object and motive of defire are the fame thing. Hence to defire without an object, that is, without a motive, is a folecifm in language. As if one fhould aflc, if you could eat without food, or breathe without air. From this account of volition it appears, that convulfions of the 326 DISEASES Sect. XXXIV. i. t. the mufcles, as in epileptic fits, may in the common fenfe of that word be termed involuntary ; becaufe no deliberation is interpo- fed between the defire or averfion and the confequent action ; but in the fenfe of the word, as above defined, they belong to the clafs of voluntary motions, as delivered in Vol. I. Clais III. If this life of the word be difcordant to the ear of the reader, the term morbid voluntary motions, or motions in confequence of averfion, may be fubftituted in its flead. If a perfon has a defire to be cured of the ague, and has at the fame time an averfion (or contrary defire) to fwallowing an ounce of Peruvian bark ; he balances defire againfl defire, or averfion againft averfion *, and thus he acquires the power of choofing, which is the common acceptation of the word ivilling. But iri the cold fit of ague, after having difcovered that the act of fhuddering, or exerting the fubcutaneous mufcles, relieves the pain of cold ; he immediately exerts this act of volition, and fhudders, as foon as the pain and confequent averfion return, without any deliberation intervening ; yet is this act, as well as that of fwallowing an ounce of the bark, caufed by volition ; and that even though he endeavours in vain to prevent it by a weak- er contrary volition. This recalls to our minds the (lory of the hungry afs between two hay-flacks, where the two defires are fuppofed fo exactly to counteract each other, that he goes to neither of the flacks, but perifhes by want. Now as two equal and oppofite defires are thus fuppofed to balance each other, and prevent all action, it follows, that if one of thefe hay-flacks was fuddenly removed, the afs would irrefiftibly be hurried to the other, which in the common ufe of the word might be call- ed an involuntary act ; but which, in our acceptation of it, would be clafied amongfl voluntary actions, as above explained. Hence to deliberate is to compare oppofing defires or aver- fions, and that which is the moft interefling at length prevails, and produces action. Similar to this, where two pains oppofe each other, the flronger or more interefling one produces ac- tion ; as in pleurify tlfe pain from fuffbeation would produce expanfion of the lungs, but the pain occafioned by extending the inflamed membrane, which lines the chefl, oppofes this ex- panfion, and one or the other alternately prevails. When any one moves his hand quickly near another perfon's cs, the eye-lids inftantly clofe ; this act in common language is termed involuntary, as we have not time to deliberate or to exert any contrary defire or averfion, but in this work it would be termed a voluntary act, becaufe it is caufed by the faculty of volition, and after a few trials the nictitation can be prevented by a contrary or oppofinor volition. Thr Sect. XXXIV. i. i. OF VOLITION. 327 The power of oppofing volitions is beft exemplified in the ftory of Mutius Scaevola, who is faid to have thruft his hand into the fire before Porcenna, and to have fuffered it to be con- fumed for having failed him in his attempt on the life of that general. Here the averfion for the lofs of fame, or the unfatis- fied deflre to ferve his country, the too prevalent enthufiafms at that time, were more powerful than the defire of withdrawing his hand, which mult be occafioned by the pain of combuftion > of thefe oppofing volitions Vincit amor patriae, laudumque immenfa cupido. If any one is told not to fwallow his faliva for a minute, he foon fwallows it contrary to his will, in the common fenfe of that word ; but this alfo is a voluntary action, as it is performed by the faculty of volition, and is thus to be underflood. When the power of volition is exerted on any of our fenfes, they be- come more acute, as in our attempts to hear fmall noifes in the night. As explained in Section XIX. 6. Hence by our atten- tion to the fauces from our defire not to fwallow our faiiva ; the fauces become more fenfible ; and the flimulus of the fali- va is followed by greater fenfation, and confequent de fire of fwallowing it. So that the defire or volition in confequeuce of the increafed fenfation of the faliva is more powerful, than the previous defire not to fwallow it. See Vol. I. Deglutitio in- vita. In the fame manner if a modeft man wilhes not to want to make water, when he is confined with ladies in a coach of an affembly-room ; that very act of volition induces the circum- ftance, which he wilhes to avoid, as above explained j mfomuch that I once faw a partial infanity, which might be called a vol- untary diabetes, which was occafioned by the fear (and confe- quent averfion) of not being able to make water at all. It is further neceffary to obferve here, to prevent any confu- fion of voluntary, with fenfitive, or aflbciate motions, that in all the instances of violent efforts to relieve pain, thofe efforts are atfirft voluntary exertions -, but after they have been frequent- ly repeated for the purpofe of relieving certain pains, they be- come aflbciated with thofe pains, and ceafe at thofe times to be fubfervient to the will ; as in coughing, fneezing, and ftrangu- ry. Of thefe motions thofe which contribute to remove or dif- lodge the offending caufe, as the actions of the abdominal muf- cles in parturition or in vomiting, though they were originally excited by volition, are in this work termed fenfitive motions 5 but thdfe actions of the mufcles or organs of fenfe, which do not contribute to remove the offending caufe, as in general con- vulfions or in madnefs, are in this work termed voluntary mo- tions- 323 DISEASES Sect. XXXIV. i. 2, tion3, or motions in confequence of averfion, though in common language they are called involuntary ones. Thofe fenfitive un^ reftrainable actions, which contribute to remove the caufe of pain are uniformly and invariably exerted, as in coughing or fneezing •, but thofe motions which are exerted in confequence of averfion without contributing to remove the painful caufe, but only to prevent the fenfation of it, as in epileptic or cataleptic fits, are not uniformly and invariably exerted, but change from one fet of mufcles to another, as will be further explained ; and may by this criterion alfo be diftinguifhed from the former. At the fame time thofe motions, which are excited by per- petual llimulus, or by aflbciation with each other, or immedi- ately by pleafurable or painful fenfation, may properly be term- ed involuntary motions, as thofe of the heart and arteries ; as- the faculty of volition feldom affects thofe, except when it exifts in unnatural quantity, as in maniacal people. 2. It was obferved in Section XIV. on the Production of Ideas, that thofe parts of the fyftem, which are ufually termed the organs of fenfe, are liable to be excited into pain by the ex- cefs of the ftimulus of thofe objects, which are by nature adap- ted to affect them •, as of too great light, found, or preiTure. But that thefe organs receive no pain from the defect or abfence of thefe Cumuli, as in darknefs or filence. But that our other or- gans of perception, which have generally been called appetites, as of hunger, thirft, want of heat, want of frefh air, are liable to be affected with pain by the defect, as well as by the excefs of their appropriated ftimuli. This excefs or defect: of ftimulus is however to beconfidered only as the remote caufe of the pain, the immediate caufe being the excefs or defect of the natural action of the affected part, according to Sect. IV. 5. Hence all the pains of the body may be divided into thofe from excefs of motion, and thofe from de- fect of motion, which diftincHon is of great importance in the knowledge and the cure of many difeafes. For as the pains from the excefs of motion either gradually fubfide, or are in general fucceeded by inflammation ; fo thofe from defect of motion either gradually fubfide, or are in general fucceeded by convullion, or madnefs. Thefe pains are eafily diftinguifhable from each other by this circumflance, that the former are attend- ed with heat of the pained part, or of the whole body ; where- as the latter exift without increafe of heat in the pained part, and are generally attended with coldnefs of the extremities of the body ; which is the true criterion of what have been called nervous p which is probably refolvable into the more general law, that the whole fenforial power bein£ expended in ©ne mode of exertion^ ther^ Vol. I. Tx is 33tf " DISEASES Sect. XXXIV. i. $ is none to fpare for any other. Whence fyncope, or temporary apoplexy, fucceeds to epileptic convulfions. 3. Hence when any violent pain afflicts us, of which we can neither avoid nor remove the caufe, we foon learn to endeavour to alleviate it, by exerting fome violent voluntary effort, as men- tioned above ; and are naturally induced to ufe thofe mufcles for this purpofe, which have been in the early periods of our lives moft frequently or moil powerfully exerted. Now the firft mufcles, which infants ufe moil frequently, arc thofe of refpiration ; and on this account we gain a habit of holding our breath, at the fame time that we ufe great efforts to exclude it, for this purpofe of alleviating unavoidable pain 5 or we prefs out our breath through a fmall aperture of the larynx, and fcream violently, when the pain is greater than is relievable by the former mode of exertion. Thus children fcream to relieve any pain either of body or mind, as from anger, or fear of being beaten. Hence it is curious to obferve, that thofe animals, who have more frequently exerted their mufcles of refpiration violently, as in talking, barking, or grunting, as children, dogs, hogs, fcream much more, when they are in pain, than thofe other animals, who ufe little or no language in their common modes of life j as horfes, fheep, and cows. The next moil frequent or mofl powerful efforts, which in- fants are firft tempted to produce, are thofe with the mufcles in biting hard fubftances ; indeed the exertion of thefe mufcles is verv powerful in common maftication, as appears from the pain we receive, if a bit of bone is unexpectedly found amongft our foftcr food ; and further appears from their acting to fo great mechanical difadyantage, particularly when we bite with the in- Clfores, or canine teeth ; which are firil formed, and thence affe firft ufed to violent exertion. Hence when a perfon is in great pain, the caufe of which he cannot remove, he fets his teeth firmly together, or bites fome fubftance between them with great vehemence, as another mode of violent exertion to produce a temporary relief. Thus we have a proverb where no help can be had in pain, " to grin and abide ;" and the tortures of hell are faid to be attended with " gnafhing of teeth." Hence in violent fpafmodic pains I have feen people bite not only their tongues, but their arms or fingers, or thofe of the at- tendants, or any object which was near them ; and alfo ftrike, pinch, or tear, others or themfelves, particularly the part of their own body, which is painful at the time. Soldiers, who die of painful wounds in battle, are faid in Homer to bite the ground. Sect. XXXIV. i. 4. OF VOLITION. 53 r ground. Thus alfo in the bellon, or colica faturnina, the pa- tients are faid to bite their own fleth, and dogs in this difeafe to bite up the ground they lie upon. It is probable that the great endeavours to bite in mad dogs, and the violence of other mad animals, are owing to the fame caufe* 4. If the efforts of our voluntary motions are exerted with ftill greater energy for the relief of fome difagreeable ferjfation. .convulsions are produced •, as the various kinds of epilepfy, and in fomehyfteric paroxyfms. In all thefe difeal.es a pun or difa- greeable fenfation is produced, frequently by worms, or acidity "in the bowels, or by a difeafed nerve in the fide, or head, or by the pain of a difeafed liver. In fome conftitutions a more intolerable degree of pain is produced in fome part at a diftance from the caufe by fenfitive aflbciation, as before explained ; thefe pains in fuch conftitutions arife to fo great a degree, that I verily believe no artificial tor- tures could equal fome, which I have witnefTed ; and am confi- dent life would not have long been preferved, unlefs they had been {oon diminifhed or removed by the univerfal convuliion of the voluntary motions, or by temporary madnefs. In fome of the unfortunate patients I have obferved, the pain, has rifen to an inexpreflible degree, as above defcribed, before £he convulfions have fupervened ; and which were preceded by (creaming, and grinning ; in others, as in the common epilepfy, the convuliion has immediately fucceeded the commencement of the difagreeable fenfations ; and as a ftupor frequently fucceeds the convulfions, they only feemed to remember that a pain at the ftomach preceded the fit, or fome other uneafy feel ; or mote frequently retained no memory at all of the immediate caufe of the paroxyfm. But even in this kind of epilepfy, where the pa- tient does not recollect any preceding pain, the paroxyfms gen- erally are preceded by a quivering motion of the under jaw, with a biting of the tongue j the teeth afterwards become prefix- ed together with vehemence, and the eyes. are then convuifed, before the commencement of the univerfal convuliion ; which are all efforts to relieve pain. The reafon why thefe convulfive motions are alternately exerted and remitted was mentioned above, and in Seel. XII. 1. 3. when the exertions are fuch as give a temporary relief to the pain, which excites them, they ceafe for a time, till the pain is again perceived; and then new exertions are produced for its relief. We fee daily examples of this in the loud reiterated laughter of fome people ; the pleafurable fenfation, which ex- cites this laughter, arifes for a time fo high as to change its name and become painful : the convulfive motions of the. refpiratory mufcleg 332 DISEASES Sect. XXXIV. i, 4. mufcles relieve the pain for a time ; we are, however, unwil- hng fo lofe the pleafure, and prefently put a flop to this exer- tion, and immediately the pleafure recurs, and again as inftantly rifes info pain. All of us have felt the pain of immoderate laughter •, children have been tickled into convulfions of the whole body ; and others have died in the act of laughing j probably from a paralyfig fucceeding the long continued actions of the mufcles of refpiration. Hence we learn the reafon, why children, who are fo eafily excited to laugh by the tickling of other people's fingers, cannot tickle themfeives into laughter. The exertion of their hands in the endeavour to tickle themfeives prevents the necemty of any exertion of the refpiratory mufcles to relieve the excefs of pleaf- urable affection. See Sect. XVII. 3. 5. Chryfinpus is recorded to have died laughing, when an afs was invited to fup with him. The fame is related of one of the popes, who, when he was ill, faw a tame monkey at his bed-fide put on the holy tiara. Hall. Phyf. T. III. p. 306. There are inftances of epilepfy being produced by laughing recorded by Van Swieten, T- III. 402 and 308. And it is well known, that many people have died inflantaneoufly from the painful excefs of joy, which probably might have been prevent- ed by the exertions of laugher. Every combination of ideas, which we attend to, occafions pain or pleafure ; thofe which occafion pleafure, furnifh either ■Social or felfifh pleafure, either malicious or friendly, or lafcivi- cus, or fublime pleafure ; that is, they give us pleafure mixed with other emotions, or they give us unmixed pleafure', without occafioning any other emotions or exertions at the fame time. This unmixed pleafure, if it be great, becomes painful, like all other animal motions from ftimuli of every kind ; and if no other exertions are occafioned at the fame time, we ufe the ex- ertion of laughter to relieve this pain. Hence laughter is occa- sioned by fuch wit as excites fimply pleafure without any other emotion, fuch as pity, love, reverence. For fublime ideas are mixed with admiration, beautiful ones with love, new ones with furprife •, and thefe exertions of our ideas prevent the action of laughter from being neceflary to relieve the painlul pleafure above defcribed. Whence laughable wit coniifts of frivolous ideas, without connexions of any confequence, fuch as puns on words, or on phraies, incongruous junctions ol ideas i on which account laughter is fo frequent in children. Unmixed pleafure lefs than that, which caufes laughter, caufes fleep, as in finging children to fleep, or in fiighi intoxication from wine 01 food. .Sec Sect. XVIII. 1?,. j. if Sect. XXXIV. i. 5. OF VOLITION. 333 5. If the pains, or difagreeable fenfations, above defcribed do not obtain a temporary relief from thefe convulfive exertions of the mufcles, tbofe convulfive exertions continue without remif- fion, and one kind of catalepfy is produced. Thus when a nerve qr tendon produces great pain by its being inflamed or wounded, the patient fets his teeth firmly together, and grins violently, to diminiih the pain ; and if the pain is not relieved by this exer- tion, no relaxation of the maxillary mufcles takes place, as in the convulsions above defcribed, but the jaws remain firmly fixed together. This locked jaw is the mofl frequent inftance of cataleptic fpafm, becaufe we are more inclined to exert the mufcles fubfervient to maftication from their early obedience to violent efforts of volition. But in the cafe related in Seel:. XIX. on Reverie, the catalep- tic lady had pain in her upper teeth ; and preiiing one of her hands vehemently againfl her cheek bone to diminim this pain, ir remained in that attitude for about half an hour twice a day, till the painfui paroxyfm was over. I have this very day feen a young lady m this difeafe, (with which fne has frequently been afflicted ;) fhe began to-day with violent pain mooting from one (ide of the forehead to the occi- put, and after various ftruggles lay on the bed with her fingers and wrifts bent and itiff for about two hours ; in other refpects fhe feemed in a fyncope with a natural pulfe. She then had in- tervals of pain and of fpafm, and took three grains of opium every hour till fhe had taken nine grains, before the pains and fpafm ceafed. There is, however, another fpecies of fixed fpafm, which dif- fers from the former, as the pain exifts in the contracted mufcle, and would feem rather to be the confequence than the caufe of the contraction, as in the cramp in the calf of the leg, and in many other parts of the body. In thefe fpafms it fhould feem, that the mufcle itfelf is firll thrown into contraction by fome difagreeable fenfation, as of cold ; and that then the violent pain is produced by the great contraction of the mufcular fibres extending its own tendons, which are faid to be fenfible to extenfion only ; and is further explained in Sect. XVIII. 15. 6. Many inftances have been given in this work, where after violent motions excited by irritation, the organ has become qui- efcent to lefs, and even to the great irritation, which induced it into violent motion ; as after looking long at the fun or any bright colour, they ceafe to be feen ; and after removing from bright day-light into a gloomy room, the eye cannot at firll per- ceive the objects, which Simulate it lefs. Similar to this is the fyncope, 334 DISEASES Sect. XXXIV. i. 7, fyncope, which fucceeds after the violent exertions of our vol- notary motions, as after epileptic fits, for the power of volition aOs in this cafe as the flimulus in the other. This fyncope is a temporary paify, or apoplexy, which ceafes after a time, the muf- cles recovering their power of being excited into action by the efforts of volition ;*as the eye in the circumftance above men- tioned recovers in a little time its power of feeing objects in a gloomy room ; which were invilibie immediately after coming out of a ftronger light. This is owing to an accumulation of fenforial power during the inaction of thofe fibres, which were before accuftomed to perpetual exertions, as explained in Sect. XII. 70 1. A (lighter degree of this difeafe is experienced by every oae after great fatigue, when the mufcles gain fuch inabili- ty to further adlion, that we are obliged to reft them for a while, or to fummon a greater power of volition to continue their motions. In all the fyncopes, which I have feen induced after convul- sive fits, the puljfe has continued natural, though the organs of fenfe, as well as the locomotive mufcles, have ceafed to perform their functions; for it is necefTary for the perception of objects, that the external organs of fenfe mould be properly excited by the voluntary power, as the eye-lids mult be open, and perhaps the mufcles of the eye put into action to diftend, and thence give greacer pellucidity to the cornea, which in fyncope, as in (icathj appears flat and lefs tranfparent. The tympanum of the car alfo feemj to require a voluntary exertion of its mufcles, to gain its due tenfion, and it is probable the other external organs of fenfe require a fimilar voluntary exertion to adapt them to the diftinct perception of objects. Hence in fyncope as in fleep, as the power of volition is fufpended, no external objects are perceived. See Se£t. XVIII. 5. During the time which the patient lies in a fainting fit, the fpirit of animation becomes ac- cumulated ; and hence the mufcles in a while become irritable their ufual llinmlaiion, and the fainting fit ceafes. See Sect. XII. 7. 1. 7. If the exertion of the voluntary motions has been ftill more energetic, the quiefcence, which fucceeds, is {o complete, that they cannot again be excited into action by the efforts of the will. In this manner the pally, and apoplexy (which is an uni- verfal paify) are frequently produced after convulfions, or other violent exertions j of this 1 (hall add a few inftanccs. Platn^rus mentions ibme, who have died apoplectic from vio- lent exertions in dancing j and Dr. Mead, in his efTay on Poi- fens, records a patient in the hydrophobic, who at one effort hu^e the cords which bound him, and at the fame inftant ex- pired. Sect. XXXIV, i. ?, OF VOLITION. 335 pired. And it is probable, that fhofe, who have expired from immoderate laughter, have died from this paralyfis coniequent to violent exertion, Mrs. Scott of StafFord was walking in her garden in perfect health with her neighbour Mrs. % the b.t- ter accidentally fell into a muddy rivulet, and tried in vain to difengage herfelf by the amftance of Mrs. Scott's hand. Mr?. Scott exerted her utmoft power for many minutes, firft to aflhl her friend, and next to prevent herfelf from being pulled into the morafs, as her diftrefTed companion would not dileng her hand. After other afiiftance was procured by their unit fcreams, Mrs. Scott walked to a chair about twenty yards from the brook, and was feized with an apoplectic ftroke : which continued many days, and terminated in a total lofs of her right arm, and her fpeech ; neither of which (he ever after perfectly recovered. It is faid, that many people in Holland have died after (taring too long or too violently on their frozen canals ; it is probable the death of thefe, and of others, who have died fuddenly in fwimming, has been owing to this great quiefcence or paralyfis * which has fucceeded very violent exertions, added to the con- comitant cold, which has had greater effect, after the fuilerers had been heated and exhaufted by previous exercife. I remember a young man of the name of Nairne at Cambridge., who walking on the edge of a barge fell into the river. His coufin and fellow-ftudent of the fame name, knowing the other could not fwim, plunged into the water after him, caught him by his clothes, and approaching the bank by a vehement exertion propelled him fafe to the land, but that inftant, feized, as was fuppofed, by the cramp, or paralyfis, funk to rife no more. The reafon why the cramp of the mufcles, which compofe the calf of the leg, is fo liable to afFeft fvvimmers, is, becaufe thefe muf- cles have very weak antagonifts, and are in walking generally elongated again after their contraction by the weight of the body on the ball of the toe, which is very much greater than the re- fiftance of the water in fwimming. See Section XVIII. 15. It does not follow that every apoplectic or paralytic attack u immediately preceded by vehement exertion j the quiefcence, which fucceeds exertion, and which is not fo great as to be term- ed paralyfis, frequently recurs afterwards at certain periods ; and by other caufes of quiefcence, occurring with thofe period^ as was explained in treating of the paroxyfms of intermitting fevers ; the quiefcence at length becomes fo great as to be in- capable of again being removed by the efforts of volition, and complete paralyfis is formed. SeeSeaion XXXII. 3. 2. Many of the paralytic patients, whom I have feen, have evi- dently 33<> DISEASES Sect. XXXIV. 2. i) dently had difeafcd livers from the too frequent potation of fpirituous liquors ; lome of them have had the gutta rofea on their faces and breads ; which has in fome degree receded either ipontaneoutly, or by the ufe cf external remedies, and the para- lytic itroke has fuccecded ; and as in feveral perfons, who have drunk much vinous fpirits, I have obferved epileptic fits to com- mence at about forty or fifty years of age, without any heredita- ry taint, from the ftimulus, as I believed, of a difeafed liver ; I was induced to afcribe many paralytic cafes to the fame fource ; which were not evidently the effect of age, or of unacquired de- bility. And the account given before of dropfies, which very frequently are owing to a paralyfis of the abforbent fyftem, and are generally attendant on free drinkers of fpiriiuous liquors, confirmed me in this opinion. The difagreeable irritation of a difeafed liver produces exer- tions and confequent quiefcence ; thefe by the accidental con- currence of other caufes of quiefcence, as cold, folar or lunar periods, inanition, the want of their ufual portion of fpirit of wine, at length produces paralyfis. This is further confirmed by obferving, that the mufcles, we moil frequently, or moft powerfully exert, are molt liable to palfy ; as thofe of the voice and of articulation, arid of thofe paralytics which I have feen, a much greater proportion have loft the ufe of their right arm ; which is fo much more gener- ally exerted than the left. I cannot difmifs this fubject without obferving, that after a paralytic ftroke, if the vital powers are not much injured, the patient has all the movements of the affected limb to learn over again, juft as in early infancy ; the limb is firft moved by the irritation of its mufcles, as in ftretching, (of which a cafe was related in Section VII. 1. 3.) or by the electric concufiion ; afterwards it becomes obedient to fenfation, as in violent danger or fear ; and laftly, the mufcles become again affociated with volition, and gradually acquire their uiual habits of acting to- gether. Another phenomenon in palfies is, that when the limbs of one fide are difabled, thofe of the other are in perpetual motion. This can only be explained from conceiving that the power of motion, whatever it is, or wherever it refides, and which is capa- ble of being exhaufted by fatigue, and accumulated in reft, is now lefs expended, whilit one half of the body is incapable of receiving its ufual proportion of it, and is hence derived with greater eafe or in greater abundance into the limbs, which re- main unaffected. II. 1. The excefsor defect of voluntary exertion produces fimilar Sect. XXXIV. 2. 2. OF VOLITION. 337 fimilaf effects upon the fenfual motions, or ideas of the mind, aa thofe already mentioned upon the mufcular fibres. Thus when any violent pain, arifing from the defect of fome peculiar hamu- lus, exifts either in the mufcular or fenfual fy items of fibres, and which cannot be removed by acquiring the defective ftimulus ; as in fome confcitutions cotivulfiorfs of the mufeles are produced to procure a temporary relief, fo in other constitutions vehement voluntary exertions of the ideas of the mind are produced for the fame piirpofe ; for during this exertion, like that of the mui- cles, the pain either vanifhes or is dirmfiifh'ed : this violent ex- ertion co'hititu'tes madnefs *, a*id in many cafes I have ieen the madnefs take place, and the convulfions ceafe, and reciprocally the madnefs ceafe, and the convulfions fupervene. See Section III. 5. 8. 2. Madnefs is diftinguilhable from delirium, as in the latter the patient knows not the place where he refides, nor the per- sons of his friends or attendants, nor is confcious of any external objects* except when fpoken to with a louder voice, or ftUnu- lated with unufual force, and even then he foon relapfes into a Hate of inattention to every tiling about him. Whilft in the former he is perfectly fenfible to every thing external, but has the voluntary powers of his mind intenfeiy exerted on fome par- ticular obiect of his deilre or averfio'n, he harbours in his thoughts a fufpicion of all mankind, left they fhouLi counteract his defigns ; and while he keeps his intentions, and the motives of his actions profoundly fecret ; he is perpetually ftudying the means of acquiring the object of his wifli, or of preventing or revenging the injuries he fufpects. 3. A late French philoibpher, Mr. Kelvetius, has deduced al- moit all our actions from this principle of their relieving us from the ennui or tccdium vitse \ and true it is, that our defiles or averfions are the motives of all our voluntary actions ; and human nature feems to excel other animals in the more facile ufe of this voluntary power, and on that account is more liable to infanity than other animals. But in mania this violent exer- tion of volition is expended en miltaken objects, and would not be relieved, though we were to gain or efcape the objects, that excite it. Thus I have feen two inftances of madmen, who con- ceived that they had the itch, and fever.il have believed they had the venereal infection, without in reality having a fymptom of either of them. They have been perpetually chinking upon this fubject, and fome of them were in vain fahvated with deuVn of convincing them to the contrary. 4. In the minds of mad people thofe volitions alone cxift, which are unmixed with fenfation ; immoderate fufmcion is Vol. I. Uu generally 33* DISEASES Sect. XXXIV. 2. j. generally the firfl fymptom, and want of (hame, and want of delicacy about c lean line fs. Suspicion is a voluntary exertion of the mind arifing from the pain of fear, which it is exerted to relieve : fliame is the name of a peculiar difagreeable fenfation, fee Fable cf the Bees, and delicacy about cleaniinefs arifes from another difagreeable fenfation. And therefore are not found in. the minds of maniacs, which are employed folely in voluntary exerticii3. Hence the molt modeft women in this difeafe walk, naked amongft men without any kind of concern, ufe obfeene difcourfe, and have no delicacy about their natural evacuations. 5. Nor are maniacal people more attentive to their natural appetites, or to the irritations which furround them, except as far as may refpect their fufpicions or defigns ; for the violent and perpetual exertions of their voluntary powers of mind prevent their perception of almoft every other object, either of irritation or of fenfation. Hence it is that they bear cold, hunger, and fa- tigue, with much greater pertinacity than in their fober hours, and are lefs injured by them in refpett to their general health. Thus it is allerted by hiftorians, that Charles the Twelfth of Sweden llept on the fuow, wrapped only in his cloak, at the fiege of Frederick (tad, and bore extremes of cold and hunger, and fatigue, under which numbers of his foldiers periihed ; becaufe the king was infane with ambition, but the foldier had no fuch powerful stimulus to preferve his fyttem from debility and death. (5. Betides the insanities ariiing from exertions in eonfequence of pain, there is alfo a pieafurable infinity, as well as a pleafura- ble delirium ; as the infanity of perfonal vanity, and that of re- ligious fanaticifm. When agreeable ideas excite into motion th fenforial power of fenfation, and this again caufes other trains of agreeable ideas, a coniiant dream of pieafurable ideas fucceeds> and produces pieafurable delirium. So when the fenforial power of volition excites agreeable ideas, and the pleafure thus produ- ced excites more volition in its turn, a confeant flow of agreea- ble voluntary ideas fucce,eds ; which when thus exerted in the extreme conuitutes infanity. Thus when our mufcular aclions are excited by our fenfations of pieafure, it is termed play •, when they are excited by our volition, it is termed work ; and the former of thefe is attended with lei's fatigue, becaufe the mufcular actions in play produce in their turn more pieafurable fenfation -> which again has the property of producing more mufcular action. An agreeable in- iLmcc o'r this I law this morning. A little boy, who was tired with w.\ ed of his p;ipa to carry him. " Here," fays tint reverend doctor, " ride upon my gold-headed cane ;" and the plea-fed child, putting it between his \egzy gallopped away with Sect. XXXIV. 2. 7. OF VOLITION. 339 with delight, and complained no more of his fatigue. Here the aid of another fenforial power, that of pleafurable fenfation, fu- peradded vigour to the exertion of exhaufted volition. Which could otherwife only have been excited by additional pain, as by the lafh of flavery. On this account where the whole fenforial power has been exerted on the contemplation of the promised joys of heaven, the faints of all perfecuted religions have borne the tortures of martyrdom with cnherwifc; unaccountable lirmnefso 7. There are Jfome difeafes, which obtain at lead a temporary relief from the exertions of infanity ; many inftances of dropfies being thus for a time cured are recorded. An elderly woman labouring with afcites I twice faw relieved for fome weeks by infanity, the dropfy ceafed for feveral weeks, and recurred again alternating with the infanity. A man armtted with difficult ref- piration on lying down, with very irregular pulfe, znd cedema- tous legs, whom I faw this day, has for above a week been much relieved in refpect to all thofe fymntoms by the acceiiion of in- fanity, which is (hewn by inordinate fulpicion, and great anger. In cafes of common temporary anger the increafed action of the arterial fyflem is feen by the red lkin, and increafed pulfe, with the immediate increafe of mufcular activity. A friend of mine, when he was painfully fatigued by riding on hbrfe&*ckf was accuftomed to call up ideas into his mind, which uled to ex- cite his anger or indignation, and thus for a time at leaft relieved the pain of fatigue. By this temporary infanity, the effect of the voluntary power upon the whole of his fyflem was increafed ; as in the cafes of dropfy above mentioned, it would appear, that the increafed action of the voluntary faculty of the fenferium ar7e£ted the abforbent fyftem, as well as the fecerning one. 8. In refpecr. to relieving inflammatory pains, and removing fever, I have feen many inftances, as mentioned in Sect. XII. 2. 4. One lady, whom I attended, had twice at fome years in- terval a locked jaw, which relieved a pain on her fternum with peripneumony. Two other ladies I faw, -who towards the end of violent peripneumony, in which they frequently loft blood, were at length cured by infanity fupervening. In the former the increafed voluntary exertion of the mufclesof the jaw, in the latter that of the organs of fenfe, removed the difeafc ; that is, the difagreeable fenfation, which had produced the inflamma- tion, now excited the voluntary power, and thefe new voluntary exertions employed or expended the fuperabundant fenforial power, which had previoufly been exerted on the arterial fyftem, and caufed inflammation. Another cafe which I think worth relating, was of a voung man about twenty j he had laboured under ah irritative fever witfc 34.0 DISEASES Sect. XXXIV. 3. ij witlj debility for three or four weeks, with very quick and very feeble pulfe, and other ufual fymptoms of that fpeeies of typhus, fbut at this time complained much and frequently of pain of his legs and feet. When thofe who attended Jiim were nearly in defpair of his recovery, I obferved with pleafure an infanity of mind fupervene : which was totally different from delirium, as he knew his friends, calling them by their names, and the room in which he lay, but became violently fufpicious of his attend- ants, and calumniated with vehement oaths his tender mother, who fat weeping by Ins bed. On this his pulie became flower nnd firmer, but the quicknefs did not for fome time intirely ceafe, and he gradually recovered. In this cafe the introduction of an increased quantity of the power of volition gave vigour to thofe movements of the fyftem, which are generally only actu- ated by the power of irritation, and of affociation. Another cafe I recollect of a young man, about twenty-five, who had the fcarlet-fever, with very quick pulfe, and an univer- sal eruption on his fkin, and was not without reafen elteemed to be in great danger of his life. After a few days an infanity fu- pervened, which his friends miftook for delirium, and he gradu- ally recovered, and the cuticle peeled off. From thefe and a fevv other cafes I have always elteemed infanity to be a favoura- ble fign in fevers, and have cautioufly diftinguifhed it from de- lirium. III. Another mode of mental exertion to relieve pain, is by producing a train of ideas not only by the efforts of volition, as in infanity •, but by thofe of fenfation likewife, as in delirium and fleep. This mental effort is termed reverie, or fomnambula- tion, and is defcribed more at large in Seel. XIX. on that fub- ject. But I lhailhere relate another cafe of that wonderful dif- eafe, which fell yefterday under my eye, and to which I have feen many analogous alienations of mind, though not exactly iimilar in all circumftances. But as all of them either began or terminated with pain or convulfion, there can be no doubt but that they are of epileptic origin, and conftitute another mode of mental exertion to relieve fome painful fenfation. I. Matter A. about nine years old, had been feized at feven every morning for ten days with uncommon fits, and had had flight returns in the afternoon. They were fuppofed to origi- nate from worms, and had been in vain attempted to be removed by vermifuge purges. As his fit was expected at feven ycfter- day morning, I faw him before that hour j he was afleep, feemed free from pain, and his pulfe natural. About {even he began to complain of pain about his navel, or more to the left fide, and in a few minutes had exertions of his arms and legs like fwimming. JSect. XXXIV. 3. 2. OF VOLITION. 341 fvrlmming. He then for half an hour liuntecl a pack of hounds 5 as appeared by his hallooing, and calling the dogs by their names, and difcourfing with the attendants of tJie chafe, defcribing ex- actly a day of hunting, which ([ was informed) he had witnefied a year before, going through all the molt minute circumftances of it ; calling to people, who were then prefent, and lamenting the abfence of others, who were then alio abfent. After this jcene he imitated, as he lay in bed, fome of the plays of boys, as fwimming and jumping. He then lung an Engliih and then an Italian long ; part of which with his eyes open, and part with them clofed, but could not be awakened or excited by any vio- lence, which it was proper to ufe. After about an hour he came fuddenly to hirofelf with ap- parent furprife, and feemed quite ignorant of any part of what had patted, and after being apparently well for half an hour, he fuddenly fell into a great ftupor, with flower pulfe than natural, and a How moaning refpiration, in which he continued about another half hour, and then recovered. The fequel of this difeafe was favourable ; he was directed one grain of opium at fix every morning, and then to rife out of bed ; at half paft fix he was directed fifteen drops of laudanum in a glafs of wine and water. The firft day the paroxyfm be- came ihoner, and lefs violent. The dole of opium was increas- ed to one-half more, and in three or four days the fits left him. The bark and filings of iron were alfo exhibited twice a day 5 and I believe the complaint returned no more. 2. In this paroxyfm it muft be obferved, that he began with pain, and ended with ftupor, in both circumftances refemblin-y a fit of epiiepfy. And that therefore the exertions both of mind and body, both the voluntary ones, and thofe immediately excited \>y pleafurable fenfation, were exertions to relieve pain. The hunting fcene appeared to be rather an ad: of memory than of imagination, and was therefore rather a voluntary exertion, though attended with the pleafurable eagernefs, which was the confequence of thefe ideas recalled by recollection, and not the caufe of them. Thefe ideas thus voluntarily recollected were fucceeded by fen- fations of pleafure, though his fenfes were unaffected by the itimuli of vifible or audible objects ; or fo weakly excited by them as not to produce fenfation or attention. And the pleaf- ure thus excited by volition produced other ideas and other mo- tions in confequence of the fen forial power of fenfation. Whence the mixed catenations of voluntary and fenfitive ideas and mufcular motions in reverie ; which, like every other kind of 34* DISEASES Sect. XXXIV. 3. 3. of vehement exertion, contribute to relieve pain, by expending a large quantity of fenforial power. Thofe fits generally commence duririg fleep, from whence I fuppofe they have been thought to have fome connexion with fleep, and have thence been termed Somnambulifm ; but their commencement during fleep is owing to our increafed excita- bility by internal fenfations at that time, as explained in Sect. XVlII. 14 and 15, and not to any fimilitude between reverie and fleep. 3. I was once concerned for a very elegant and ingenious young lady, who had a reverie on alternate days, which continu- ed nearly the whole day •> and as in her days of difeafe fhe took up the fame kind of ideas, which fhe had canverfed about on the alternate day before, and could recollect nothing of them 011 her well day ; (lie appeared to her friends to poiTefs two minds. This cafe alfo was of the epileptic kind, and was cured, with fome relapfes, by opium administered before the commencement of the paroxyfm. 4. Whence it appears, that the methods of relieving inflam- matory pains, is by removing all ftimulus, as by venefection, cool air, mucilaginous diet, aqueous potation, filence, darknefs. The methods of relieving pains from defect: of ftimulus is by fupplying the peculiar ftimulus required, as of food, or warmth. And the general method of relieving pain is by exciting into action fome great part of the fyftem for the purpofe of expend- ing a part of the fenforial power. This is done either by ex- ertion of the voluntary ideas and mufcles, as in infanity and convuffion 5 or by exerting both voluntary and fenfitive mo- tions, as in reverie ; or by exciting the irritative motions by wine or opium internally, and by the warm bath or blifters ex- ternally ; or laftly, by exciting the feniitive ideas by good news, affecting ftories, or agreeable paflions. SECT. Sect. XXXV. i. i. ASSOCIATION. 343 SECT. XXXV. DISEASES OF ASSOCIATION. I. t . Sympathy of ccnfent of parts. Primary and fecondary parts of an affociated train of motions reciprocally affecl each other. Parts of irritative trains of motion affecl each other in four ways.- Sympathies ofthejkinandflomach. Flufhing of the face after a meal. Eruption of the f mall-pox on the face. Chilnefs after a meal. 2. Vertigo from intoxication. 3. Abforption from the lungs and pericardium by emetics. In vomiting the aclions of the flomach are decreafedy not increafed. Digeflionflrengthened after an emetic. Vomiting from deficiency of fenforial power. 4. Dyfpncea from cold bathing. Slow pulfe from digitalis. Death from gout i?i the flomach. II. 1. Primary and fecondary parts of fenfitive offociations affecl each other. Pain from gall-floneg from urinary flone. Hemicrania. Painful epilepfy. 2. Gout and red face from inflamed liver. Shingles from inflamed kidney. 3. Coryza from cold applied to the feet. Hepatitis. 4. Pain of fijoulders from inflamed liver. III. Difeafes from the affecta- tions of ideas. I. 1. Many fynchronous and fuGceffive motions of our muf- cular fibres, and of our organs of fenky or ideas, become afibci- ated fo as to form indiflbluble tribes or trains of action, as fhewn in Section X. on AfTociate Motions. Some conftitutions more eafily eftabiifh thefe aflbciations, whether by voluntary, fenfitive, or irritative repetitions, and fome more eafily lofe them again, Us (hewn in Section XXXI. on Temperaments. When the beginning of fuch a train of actions becomes by any means difordered, the fucceeding part is liable to become disturbed in confequence, and this is commonly termed fympa- thy or confent of parts by the writers of ^medicine. For the more clear underftanding of thefe fympathies we muft confrder a tribe or train of actions as divided into two parts, and call one of them the primary or original motions, and the other the fecondary or fympathetic ones. The primary and fecondary parts of a train of irritative actions may reciprocally affect each other in four different manners. 1. They may both be exerted with greater energy than natural. 2. The former may act with greater, and the latter with lefs energy. 3. The former may act with lefs, and the latter with greater energy. 4. They may both act with lefs energy than natural. I (hall now give an example of each kind of thef* modes 344 DISEASES Skct. XXXV. u z; modes of action, and endeavour to fhew, that though the pri- mary and fecondary parts of thefe trains or tribes of motion arc connected by irritative ailoeiation, or their previous habits of acting together, as defcribed in Seel:. XX. on Vertigo. Yet that their acting with fimilar or difhmilar degrees of energy, depends on die greater or lefs quantity of fenforial power, whi< the primary part of the train expends in its exertions. The actions of the itomach conftitiue fo important a part of the afTociations of both irritative and fenfitive motions, that it is faid to fympathize with almoft every part of the body ; the fir ft example, which I fhall adduce to mew that both the primary and fecondary parts of a train of irritative afTociations of motion act with increafed energy, is taken from the confent of the fkiii with this organ. When the action of the fibres of the ftomach is increafed, as by the ftimulus of a full meal, the exertions of the cutaneous arteries of the face become increafed by their ir- ritative afTociations with thofe of the ftomach, and a glow or flushing of the face fucceeds. For the fmall veflels of the fkin of the face having been more accuftomed to the varieties *bf ac- tion, from their frequent expofure to various degrees of cold and heat, become more eafily excited into increafed action, than thofe of the covered parts of our bodies, and thus act with more ener- gy from their irritative or fenfitive aflbciations with the ftom- ach. On this account in fnrall-pox the eruption in confequence of the previous affection of the ftomach breaks out a day fooner on the face than on the hands, and two days fooner than on the trunk, and recedes in fimilar times after maturation. But fecondly, in weaker conftitutions, that is, in thofe who poflefs lefs fenforial power, fo much of it is expended in the in- creafed actions of the fibres of the ftomach excited by the ftimu- lus of a meal, that a fenfe of chilnefs fucceeds inftead of the uni- versal glow above mentioned; and thus the fecondary part of the afTociated train of motions is diminifhed in energy, in conie- cuence of the increafed activity of the primary part of it. 2. Another inftance of a fimilar kind, where the fecondary part of the train acts with lets energy in confequence of the greater exertions of the primary part, is the vertigo attending in- toxication ; in this circumftance fo much fenforial power is ex- pended on the ftomach, and on its nearelt or more ftrongly afTo- ciated motions, as thofe of the fubcutaneous veflels, and proba- bly of the membranes of fome internal vilcera, that the irritative motions of the retina become imperfectly exerted from defi- ciency of fenforial power, as explained in Sect. XX. and XXI. 3. on Vertigo and on Drunkennefs, and hence the daggering ine- briate cannot completely balance himfclf by fuch indiilinct vifion. 3- A jSect. XXXV. r. 3. OP ASSOCIATION. 345 3. An inftance of the third circumftance, where the primary part of a train of irritative motions acts with lefs, and the fec- ondary part with greater energy, may be cbferved by making the following experiment. If a perfon lies with his arms and fhoulders out of bed, till they become cold, a temporary coryza -or catarrh is produced ; fo that the paffage of the noftrils be- comes totally obftructed ; at lead this happens to many people ; and then on covering the arms and (boulders, till they become warm, the pafTage of the noftrils ceafes 2gain to be obftructed, and a quantity of mucus is difcharged from them. In this cafe the quiefcence of the veffels of the fkin of the arms and moul- ders, occafioned by expofure to cold air, produces by irritative affociation an increafed action of the veffels of the membrane of the noftrils ; and the accumulation of fenforial power during the torpor of the arms and (boulders is thus expended in producing a temporary coryza or catarrh. Another inftance maybe adduced from the fympathyor con- fent of the motions of the ftomach with other more diitant links of the very extenfive tribes or trains of irritative motions affoci- ated with them, defcribed in Seel. XX. on Vertigo. When the actions of the fibres of the ftomach are diminished or invert- ed, the actions of the abforbent veffels, which take up the mucus from the lungs, pericardium, and other ceils of the body, be- come increafed, and abforb the fluids accumulated in them with greater avidity, as appears from the exhibition of foxglove, anti- mony, or other emetics, in cafes of anafarca, attended with un- equal pulfe and difficult refpiration. That the act of naufea and vomiting is a decreafed exertion of the fibres of the ftornach may be thus deduced •, when an emetic medicine is adminiftered, it produces the pain of ficknefs, as a difagreeable tafte in the mouth produces the pain of naufea ; thefe pains, like that of hunger, or of cold, or like thofe, which are ufually termed nervous, as the head-ach or hemicrania, do not excite the organ into greater action •, but in this cafe I im- agine the pains of ficknefs or of naufea counteract or deftroy the pleafurable fenfation, which feems neceffary to digeftion, as .(hewn in Sea. XXXIII. 1. 1. The periftaltic motions of the [1 fibres of the ftomach become enfeebled by the want of this ftimulus of pleafurable fenfation, and in confequence flop for a r time, and then become inverted ; for they cannot become invert- ed without being prevroufly flopped. Now that this inverfion ! of the trains of motion of the fibres of the ftomach is owing to the deficiency of pleafurable fenfation is evinced from this cir- cumftance, that a naufeous idea excited by words will produce vomiting as effectually as a naufeous drug. Vol. I. W w Hence 34^ DISEASES Sect. XXXV. r. 4, Hence it appears, that the aft of naufea or vomiting expends lefs fenforial power than the ufual periftaltic motions of the ftomach in the digeftion of our aliment ; and that hence there is a greater quantity of fenforial power becomes accumulated in the fibres of the ftomach, and more of it in confequence to fpare for the action of thofe parts of the fyftem, which are thus affociated with the ftomach, as of the whole abforbent ferie:; of vefTels, and which are at the fame time excited by their ufual ftimuli. From this we can underftand, how after the operation of an emetic the ftomach becomes more irritable and fenfible to the ilimulus, and the pleafure of food ; fince as the fenforial power becomes accumulated during the naufea and vomiting, the digef- tive power is afterwards exerted more forcibly for a time. It fliould, however, be here remarked, that though vomiting is in general produced by the defect of this ftimulus of pleaiurable fenfation, as when a naufeous drug is administered ; yet in long- continued vomiting, as in fea-ficknefs, or from habitual dram- drinking, it arifes from deficiency of fenforial power, which in the former cafe is exhaufted by the increafed exertion of the ir- ritative ideas of vifion, and in the latter by the frequent applica- tion of an unnatural ftimulus. 4. An example of the fourth circumftance above mentioned, where both the primary and fecondary parts of a train of mo- tions proceed with energy lefs than natural, may be obferved in the dyfpncea, which occurs in going into a very cold bath, and which has been defcribed and explained in Seel:. XXXII. 3. 2. And by the increafed debility of the pulfations of the heart and arteries during the operation of an emetic. Secondly, from the flownefs and intermiihon of the pulfations of the heart from the inceftant efforts to vomit occafioned by an over-dofe of dig- italis. And thirdly, from the total ftoppage of the motions of the heart, or death, in confequence of the torpor of the ftomach, when afFecled with the commencement or cold paroxyfm of the gout. See See"!. XXV. 17. II. 1. The primary and fecondary parts of the trains of fen- fitive a-fTociation reciprocally affect each other in different man- ners. 1. The increafed fenfation of the primary part may ceafe, when that of the fecondary part commences. 2. The increafed action of the primary part may ceafe, when that of the fecondary I part commences. 3. The primary part may have increafed fen- fation, and the fecondary part increafed action. 4. The pri-j mary part may have increafed action, and the fecondary part in- creafed fenfaticn. Examples of the firft mode, where the increafed fenfation of the Sect. XXXV. 2. i. OF ASSOCIATION. 347 the primary part of a train of fenfitive aflbciation ceafes, when that of the fecondary part commences, are not unfrequent ; as •this is the general origin of thoie pains, which continue feme ;time without being attended with inflammation, fuch as the pain at the pit of the ftomach from a (lone at the neck of the gall- bladder, and the pain of ftrangury in the glans penis from a {lone at the neck of the urinary bladder. In both thefe cafes the part, which is affected iecondarily, is believed to be much more fen- fible than the part primarily affected, as defcribed in the cata- logue of difeaies, Clafs II. 1. 1. 11. and IV. 2. 2. 2. and IV. 2. 2. 4. The hemicrania, or nervous 'head-ach, as it is called, when it .originates from a decaying tooth, is another difeafe of this kind ; as the pain of the carious tooth always ceafes, when the pain over one eye and temple commences. And it is probable, that the violent pains, which induce convulfions in painful epilepfies, are produced in the fame manner, from a more fenfible part fympathizing with a difeafed one of lefs fenfibility. .See Cata_- logue of difeafes, Clafs IV. 2. 2. 8. and III. 1. 1. 6. The lait tooth, or dens fapientia?, of the upper jaw moil fre- quently decays firft, and is liable to produce pain over the eye and temple of that -fide. The lad tooth of the under jaw is alio liable to produce a fimilar hemicrania, when it begins to decay. When a tooth in the upper jaw is the £aufe of the headach, a ilighter pain is fometimes perceived on the cheek-bone. And when a tooth in the lower jaw is the caufe of headach, a pain fometimes affects the tendons of the mufcles of the neck, which are attached near the jaws. But the ciavus hystericus, or pam about the middle of the parietal bone on one fide of the head, I have feen produced by the fecond of the molares, or grinders, of the under jaw ; of which I fhall relate the following cafe. See Clafs IV. 2. 2. 8. Mrs. , about 30 years of age, was feized with great pain about the middle of the right parietal bone, "which had continu- ed a whole day before I faw her, and was fo violent as to threat- en to occafion convulfions. Not being able to detect a decay- ing tooth, or a tender one, by examination with my eye, or by ftriking them with a tea-fpoon, and fearing bad confequences from her tendency to convulfion, I advifed her to extract the lad tooth of the under-jaw on the affected fide; which was done without any good effecl:. She was then directed to lofc blood, and to take a brillc cathartic; and after that had operated, about 6© drops of laudanum were given her, with large dofes of bark ; by which the pain was removed. In about a fortnight ihe took a cathartic medicine by ill advice, and the pain returned with 348 DISEASES Sect. XXXV. 2. 1. with greater violence in the fame place ; and, before I could ar- rive, as (he lived 30 miles from me, fhe fuffered a paralytic ftroke ; which afte&ed her limbs and her face on one fide, and relieved the pain of her head. About a year afterwards I was again called to her on account of a pain, as violent as before, exactly on the fame pare of the other parietal bone. On examining her mouth I found the fecond molaris of the under-jaw on the fide before affected was now decayed, and concluded, that this tooth had occafioned the ftroko* of the palfy by the pain and confequent exertion it had caufed.® On this account I earneftly entreated her to allow the found mo- laris of the fame jaw oppofite to the decayed one to be extract- ed ; which was forthwith done, and the pain of her head im- mediately ceafed, to the aftonifhment of her attendants. In the cafes above related of the pain exiiling in a part dif- tant from the feat of the difeafe, the pain is owing to defect, of the ufual motions of the painful part. This appears from the coldnefs, palenefs, and emptinefs of the affected veflels, or of the extremities of the body in general, and from their being no tendency to inflammation. The increafed action of the prima- ry part of thefe aflbciated motions, as of the hepatic termination of the bile-duel: from the ftimulus of a gall-ftone, or of the inte- rior termination of the urethra from the ftimulus of a (tone in the bladder, or laftly, of a decaying tcoth in hemicrania, de- prives the fecondary part of thefe aifociated motions, namely, the exterior terminations of the bile-duct or urethra, or the pain- ed membranes of the head in hemicrania, of their natural fharc of fenforial power : and hence the fecondary parts of thefe fen- fitive trains of aflbciation become pained from the deficiency of their ufual motions, which is accompanied with deficiency of fecretions and of heat. See Sect. IV. 5. XII. 5.3. XXXIV. 1. Why does the pain of the primary part of the aflbciation ceafe, when that of the fecondary part commences ? This is a queftion of intricacy, but perhaps not inexplicable. The pain of the primary part of thefe aifociated trains of motion was ow- ing to too great ftimulus, as of the ftone at the neck of the blad- der, and was confequently caufed by too great action of the pained part. This greater action than natural of the primary part of thefe aflbciated motions, by employing or expending the fenforial power of irritation belonging to the whole aflbciated train of motions, occafioned torpor, and confequent pain in the fecondary part of the aflbciated train ; which was poflefled of greater fenfibility than the primary part of it. Now the great pain of the fecondary part of the train, as foon as it commences, employs or expends the fenforial power of fenfation belonging to Sect. XXXV. 2. 2. OF ASSOCIATION. 349 to the whole affociated train of motions ; and in confequenee the motions of the primary part, though increafed by the ftimu- lus of an extraneous body, ceafe to be accompanied with pain or fenfation. If this mode of reafcning be juft it explains a curious fact, why when two parts of the body are llrongly ftimulated, the pain is only felt in one of them, though it is poffible by volunta- ry attention it may be alternately perceived in them both. In the fame manner, when two new ideas are prefented to us from 'the ftimulus of external bodies, we attend to but one of them at a time. In other words, when one fet of fibres, whether of the mufcles or organs of fenfe, contract fo ftrongly as to excite much fenfation 5 another fet of fibres contracting more weakly do not excite fenfation at all, becaufe the fenforial power of fen- fation is pre-occupied by the firft fet of fibres. So we cannot will more than one effecl: at once, though by affociations previ- oufly formed we can move many fibres in combination. Thus in the inftances above related, the termination of the bile du£t, in the duodenum, and the exterior extremity of the urethra, are more fenfible than their other terminations. When thefe parts are deprived of their ufual motions by deficiency of fenforial power, as above explained, they become painful ac- cording to law the fifth in Section IV. and the lefs pain orig- inally excited by the ftimulus of concreted bile, or of a ftone at their other extremities cafes to be perceived. Afterwards, how- ever, when the concretions of bile, or the ftone in the urinary bladder, become more numerous or larger, the pain from their increafed ftimulus becomes greater than the affociated pain ; and is then felt at the neck of the gall bladder or urinary bladder; and the pain of the glans penis, or at the pit of the ftomach, ceafes to be perceived. 2. Examples of the fecond mode, where the increafed action of the primary part of a train of fenfitive aflbciation ceafes, when that of the fecondary part commences, are alfo not unfrequent ; as this is the ufual manner of the tranflation of inflammations from internal to external parts of the fyftem, fuch as when an inflammation of the liver or ftomach is tranilated to the mem- branes of the foot, and forms the gout -, or to the fkin of the face, and forms the rofy drop ; or when an inflammation of the membranes of the kidnevs is tranilated to the fkin of the loins, and forms one kind of herpes, called fhingles ; in thefe cafes by whatever caufe the original inflammation may have been pro- duced, as the fecondary part of the train of fenfitive aflbciation is more fenfible, it becomes exerted with greater violence than the firft part of it j and by both its increafed pain, and the in- creafed 35 » DISEASES Sect. XXXV. 2. 3. creafed motion of its fibres, fo far diminifhes or exhaufts the fen- ibrial power of fenfation ; that the primary part of the train be- ing lefs fenfible ceafes both to feel pain, and to acl: with un- natural energy. 3. Examples of the third mode, where the primary part of a train of fenfitive aflbciation of motions may experience increafed fenfation, and the fecondary part increafed action, are like wife not unfrequent j as it is in this manner that mod inflammations commence. Thus, after Handing fome time in fnow, the feet become affected with the pain of cold, and a common coryza, or inflammation of the membrane of the noftrils, fucceeds. It is probable that the internal inflammations, as pleurifies, or he- patitis, which are produced after the cold paroxyfm of fever, originate in the fame manner from the fympathy of thofe parts with fome others, which were previoufly pained from quief- cence ; as happens to various parts of the fyftem during the cold fits of fevers. In thefe cafes it would feem, that the fenforial power of fenfation becomes accumulated during the pain of cold, as the torpor of the vefTels occafioned by the defect; of heat con- tributes to the increafe or accumulation of the fenforial power of irritation, and that both thefe become exerted on fome internal part, which was not rendered torpid by the cold which affected the external parts, nor by its aflbciation with them ; or which fooner recovered its fenfibility. This requires further con- fideration. 4. An example of the fourth mode, or where the primary part of a fenfitive aflbciation of motions may have increafed ac- tion, and the fecondary part increafed fenfation, may be taken from the pain of the fhoulder, which attends inflammation of the membranes of the liver, fee Oafs IV. 2. 2. 9. ; in this circum- fiance fo much fenforial power feems to be expended in the vio- lent actions and fenfations of the inflamed membranes of the liver, that the membranes aflbciated with them become quief- cent to their ufual ilimuli, and painful in confequence. There may be other modes in which the primary and feconda- ry parts of the trains of aflbciated fenfitive motions may recipro- cally affect, each other, as may be fcen by looking over Clafs IV. in the catalogue of difeafes ; all which may probably be refolved into the plus and minus of fenforial power, but we have not yet had fuiheient obfervations made upon them with a view to this doctrine. III. The aflbciated trains of our ideas may have fympathies, and their primary and fecondary parts affect, each other in fome manner fimilar to thofe above defcribed ; and may thus occafion various curious phenomena not yet adverted te, befides thofe ex- plained Sect. XXXV. 3. i. OF ASSOCIATION. 351 plained in the Sections on Dreams, Reveries, Vertigo, and Drunkennefs ; and may thus difturb the deductions of our rea- fonings, as well as the dreams of our imaginations ; prefent us with falfe degrees of fear, attach unfounded value to trivial cir- cumftances -, give occafion to our early prejudices and antipa- thies ; and thus embarrafs the happinefs of our lives. A copi- ous and curious harveft might be reaped from this province of fcience, in which, however, I fhall not at prefent wield my fickle. SECT. 3^2 PERIODS Sect. XXXVI. i. u SECT. XXXVI. OF THE PERIODS OF DISEASF I. Mufcles excited by volition foon ceafe to contracl, or by fenfathn9 or by irritation, owing to the exhaufion of [aiforial power, tilvf- cles fubjecled to lefs flimulits have their fe?f oriel power accumula- ted. Hence the periods of fotne fever;. Want of irritability after intoxication. II. I . Natural actions catenated with daily habits of life. 2. With folar periods. Periods of feep. Of evacuating the bowels. 3. Natural aclions catenated with lunar periods. Menjlr nation. Venereal or gafm of animals. Barren- nefs. III. Periods of d'feafed animal aclions from fated returns of noclurnal cold, from folar and lunar influence. Periods of diurnal fever, hecl'rc fever, quotidian, tertian, quartan fever. Periods of gout, pleurify, of fevers with arterial debility, and with arterial fir ength. Periods of rhaphania, of nervous cough) hetni- crania, arterial hemorrhages, hemorrhoids, hzmeptoe, epilepfy, palfy, apoplexy, madnefs. IV. Critical days depend on lunar periods. Lunar periods in the f mall-pox. I. If any of our mufcles be made to contract violently by the power of volition, as thofe of the fingers, when any one hangs by his hands on a fwing, fatigue foon enfues ; and the mufcles ceafe to act owing to the temporary exhauftion of the fpirit of animation ; as foon as this is again accumulated in the mufcles, they are ready to contract again by the efforts of volition. Thofe violent muicular actions induced by pain become in the fame manner intermitted and recurrent -v as in labour-pains, vomiting, tenefmus, ftrangury ; owing likewife to the temporary exhauftion of the fpirit of animation, as above mentioned. When any ftimulus continues long to act with unnatural vi- olence, fo as to produce too energetic action of any of our moving organs, thofe motions foon ceafe, though the ftimulus eontinues'to act ; as in looking long on a bright object, as on an inch-fquare of red filk laid on white paper in the funfliine. See Plate I. in Sect. III. 1. On the contrary, where lefs of the ftimulus of volition, fenfa- tion, or irritation, has been applied to a mufcie than ufual ; there appears to be an accumulation of the fpirit of animation in the moving organ ; by which it is liable to act with greater energy from lefs quantity of ftimulus, than was previoufiy nec- effary to excite it into fo great action -, as after having been im- merfed in fnow the cutaneous veflels of our hands arc excited into fee*. XXXVI. 2. i. OF DISEASES. 353 into ftronger action by the ftimulus of a lefs degree of Heat, than would previoufly have produced that effect. From hence the periods of fome fever-fits may take their ori- gin, either (imply, or by their accidental coincidence with lunar and folar periods, or with the diurnal periods of heat and cold, to be treated of below ; for during the cold fit at the commence- ment of a fever, from whatever caufe that cold fit may have been induced, it follows, 1. That the fpirit of animation muft become accumulated in the parts, which exert during this cold fit lefs than their natural quantity of action. 2. If the caufe producing the cold fit does not increafe, or becomes diminifhed ; the parts before benumbed or inactive become now excitable by fmaller ftimulus, and are thence thrown into more violent ac- tion than is natural *, that is a hot fit fucceeds the cold one. 3. By the energetic action of the fyllem during the hot fit, if it continues long, an exhauftion of the fpirit of animation takes place ; and another cold fit is liable to fucceed, from the moving fyftem not being excitable into action from its ufual ftimulus. This inirritability of the fyftem from a too great previous ftimu- lus, and confequent exhauftion of fenforial power, is the caufe of the general debility, and ficknefs, and head-ach, fome hours af- ter intoxication. And hence we fee one of the caufes of the periods of fever-fits ; which however are frequently combined with the periods of our diurnal habits, or of heat and cold,, or of folar or lunar periods. When befides the tendency to quiefcence occafioned by the expenditure of fenforial power during the hot fit of fever, fome other caufe of torpor, as the folar or lunar periods, is neceffary to the introduction of a fecond cold fit ; the fever becomes of the intermittent kind 5 that is, there is a fpace of time intervenes between the end of the hot fit, and the commencement of the next cold one. But where no exterior caufe is neceflary to the introduction of the fecond cold fit ; no fuch interval of health intervenes j but the fecond cold fit comrrlences, as foon as the fenforial power is fumciently exhaufted by the hot fit ; and the fever becomes continual. II. 1. The following are natural animal actions, which are frequently catenated with our daily habits of life, as well as ex- cited by their natural irritations. The periods of hunger and third become catenated with certain portions of time, or degrees of exhauftion, or other diurnal habits of life. And if the pain of hunger be not relieved by taking food at the ufual time, it is liable to ceafe till the next period of time or other habits recur j this is not only true in refpect to our general defire of food, but the kinds of it alfo are governed by this periodical habit ; info- Vol. I. X x much* 354 PERIODS Sect. XXXVI. 2. 2~ much that beer taken to breakfaft will difturb the digeftion of thofe, who have been accuftomed to tea •, and tea taken at din- ner will difagree with thofe, who have been accuftomed to beer. "Whence it happens, that thofe, who have weak ftomachs, will be able to digeft more food, if they take their meals at regular hours ; becaufe they have both the ftimulus of the aliment they take, and the periodical habit, to aflift their digeftion. The periods of emptying the bladder are not only dependent on the acrimony or diftention of the water in it, but are fre- quentlv catenated with external cold applied to the fkin, as in cold bathing, or wafhing the hands ; or with other habits of life, as many are accuftomed to empty the bladder before going to bed, or into the houfe after a journey, and this whether it be full or not. Our times of refpiration are not only governed by the ftimu- lus of the blood in the lungs, or our defire of frefh air, but alfo by our attention to the hourly objects before us. Hence when a perfon is earneftly contemplating an idea of grief, he forgets to breathe, till the fenfation in his lungs becomes very urgent ; and then a figh fucceeds for the purpofe of more forcibly pufti- ing forv/ards the blood, which is accumulated in the lungs. Our times of refpiration are alfo frequently governed in part by our want of a fteady fupport for the actions of our arms, and hands, as in threading a needle, or hewing wood, or in fwimming ; when we are intent upon thefe objects, we breathe at the intervals of the exertion of the pectoral mufcles. 2. The following natural animal actions are influenced by fo- lar periods. The periods of fleep and of waking depend much on the folar period, for we are inclined to fleep at a certain hour, and to awake at a certain hour, whether we have had more or lefs fatigue during the day, if within certain limits ; and are li- able to wake at a certain hour, whether we went to bed earlier or later, within certain limits. Hence it appears, that thofe who complain of want of fleep, will be liable to fleep better or longer, if they accuftom themfelves to go to reft, and to rife at certain hours. The periods of evacuating the bowels are generally connected with fome part of the folar day, as well as with the acrimony or diftention occafioned by the feces. Hence one method of cor- recting coftivenefs is by endeavouring to eftablifh a habit of evacuation at a certain hour of the day, as recommended by Mr. Locke, which maybe accomplished by ufing daily voluntary ef- forts at thofe times, joined with the ufual ftimulus of the mate- rial to be evacuated. 3. The following natural animal actions are connected with lunar Sect. XXXVI. 3. 1. OF DISEASES. 355 lunar periods. 1 . The periods of female menftruation are con- nected with lunar periods to great exactnefs, in fome inftances even to a few hours. Thefe do riot commence or terminate at the full or change, or at any other particular part of the luna- tion, but after they have commenced at any part of it, they con- tinue to recur at that part with great regularity, unlefs difturbed by fome violent circumftance, as explained in Sect. XXXII. No. 6. their return is immediately caufed by deficient venous ab- forption, which is owing to the want of the ftimulus, defigned by nature, of amatorial copulation, or of the growing fetus. When the catamenia returns fooner than the period of lunation, it fhews a tendency of the constitution to irritability -, that is to debility, or deficiency of fenforial power, and is to be relieved by fmall dofes of fteel and opium. The venereal orgafm of birds and quadrupeds feems to com- mence, or return about the moft powerful lunations at the vernal or autumnal equinoxes j but if it be difappointed of its object, it is faid to recur at monthly periods ; in this refpett refembling the female catamenia. Whence it is believed, that women are more liable to become pregnant at or about the time of their cat- amenia, than at the intermediate times ; and on this account they are feldom much miftaken in their reckoning of nine lunar periods from the lad menftruation ; the inattention to this may fometimes have been the caufe of fuppofed barrennefs, and 13 therefore worth the obfervation of thofe, who wifti to have children. III. We now come to the periods of difeafed animal actions. The periods of fever-fits, which depend on the ftated returns of nocturnal cold, are difcufied in Seel;. XXXII. 3. Thofe which originate or recur at folar or lunar periods, are alfo explained in Section XXXII. 6. Thefe we {hall here enumerate •, obferv- ing, however, that it is not more furprifing, that the influence of the varying attractions of the fun and moon, mould raife the ocean into mountains, than that it mould affect the nice fenfi- bilities of animal bodies ; though the manner of its operation on them is difficult to be underftood. It is probable however, that as this influence gradually leiTens during the courfe of the day, or of the lunation, or of the year, fome actions of our fyflem be- come lefs and lefs ; till at length a total quiefcence of fome part is induced ; which is the commencement of the paroxyfms of fever, of menftruation, of pain with decreafed action of the af- fected organ, and of confequent convulfion. 1. A diurnal fever in fome weak people is diftinctly obferved to come on towards evening, and to ceafe with a moift fkin early in the morning, obeying the folar periods. Perfons of weak conftitutions 35<5 PERIODS Sect. XXXVI. 3. a, conftitutions ar.e liable to get into better fpirits at the aecefs of the hot fit of this evening fever ; and are thence inclined to fit up late ; which by further enfeebfing them increafes the dif- eafe ; whence they lofe their ftrength and their colour. Hence delicate ladies, who do not ufe rouge, are obferved to become paler in the evening ; which is probably owing to the circulation through the whole fyftem being lefs frequently per- formed in a given time, though the pulfe is quicker *, and hence the mafs of blood becomes lefs frequently oxygenated in the lungs, and in confequence has a lefs florid colour. This pale colour therefore arifes from debility, which occurs to delicate people in the evening from the exhauftion of fenforial power during the day, and is generally attended by quicknefs of pulfe ; by which circumftance the debility may in fome degree be meafured. Another caufe of the colour of the fkin may occafionally de- pend on the increafed action of the cutaneous capillaries, as in the hot fit of fever; or by the production of new blood veffels, as in topical inflammations. And palenefs may arife from the contrary fituations, as from inaction of the cutaneous capillaries in the cold paroxyfm of fever, and from the concretion of the fides of the fmall cutaneous arteries, as in old age. 2. The periods of hectic fever, fuppofed to arife from ab- forption of matter, obey the diurnal periods like the above, having the cxacerbefcence towards evening, and the remif- fion early in the morning, with fweats, or diarrhoea, or urine with white fediment. 3. The periods of quotidian fever are either catenated with folar time, and return at the intervals of twenty-four hours; or with lunar time, recurring at the intervals of about twenty-five hours. There is great ufe in knowing with what circumftances the periodical return or new morbid motions are conjoined, as the mod: effectual times of exhibiting the proper medicines are thus determined. So if the torpor, which ufhers in an ague fit, is catenated with the lunar day ; it is known when the bark or opium muft be given, fo as to exert its principal effect about the time of the expected return. Solid opium mould be given about an hour before the expected cold fit ; liquid opium and wine about half an hour ; the bark repeatedly for fix cr eight hours previous to the expected return. 4. The periods of tertian fevers, reckoned from the com- mencement of one cold fit to the commencement of the next •cold fit, recur with folar intervals of forty-eight hours, or with lunar ones of about fifty hours. When the recurrence of thefe begins one or two hours earlier than the folar period, it fhews, that JSbct. XXXVI. 3. 5. OF DISEASES. 3S7 that the torpor or cold fit is produced by lefs external influence ; and therefore that it is more liable to degenerate into a fever with only remiflions ; fo when menftruation recurs fooner than the period of lunation, it (hews a tendency of the habit to tor- por or inirritability. 5. The periods of quartan fevers return at folar intervals of feventy-two hours, or at lunar ones of about feventy-four hours and a half. This kind of ague appears moft in -moid cold au- tumns, and in cold countries replete with marfhes. It is at- tended with greater debility, and its cold accefs moi?e difficult to prevent. For where there is previously a deficiency of fenfo- rial power the conftitution is liable to run into greater torpor from any further diminution of it ; two ounces of bark and fome fteel (hould be given on the day before the return of the cold paroxyfm, and a pint of wine by degrees a few hours before its return, and thirty drops of laudanum one hour before the cx- peeled cold fit. 6. The periods of the gout generally commence about an hour before fun-rife, which is ufually the coldeit part of the twenty-four hours. The greater periods of the gout feem alfo to obferve the folar influence, returning about the fame feafon of the vear. 7. The periods of the pleurify recur with exacerbation of the pain and fever about fun-fet, at which time venefecStion is of moft iervice. The fame may be obferved of the inflammatory rheu- matifm, and other fevers with arterial ftrength, which feem to obey folar periods ; and thofe with debility feem to obey lunar -ones. 8. The periods of fevers with arterial debility feem to obey the lunar day, having their accefs daily nearly an hour later ; and have fometimes two accefles in a day, refembling the lunar •efrecls upon the tides. 9. The periods of rhaphania, or convulfious of the limbs from rheumatic pain, feem to be connected with folar influence, re- turning at nearly the fame hour for weeks together, unlefs dis- turbed by the exhibition of powerful dofes of opium. So the periods of tuffis ferina, or violent cough with flow pulfe, called nervous cough, recur by folar periods. Five grains of opium given at the time the cough commenced difturbed the period, from feven in the evening to eleven, at which time it regularly returned for fome days, during which time the opium -was gradually omitted. Then 120 drops of laudanum were given an hour before the accefs of the cough, and it totally ecafed- The laudanum was continued a fortnight, and then gradually -difcontinued. 10. The 358 PERIODS Sect. XXXVI. 3. 10. 10. The periods of hemicrania, and of painful epilepfy, are liable to obey lunar periods, both in their diurnal returns, and in their greater periods of weeks, but are alfo induced by other exciting caufes. 11. The periods of arterial hemorrhages feem to return at folar periods about the fame hour of the evening or morning. Perhaps the venous hemorrhages obey the lunar periods, as the catamenia, and haemorrhoids. 12. The periods of the hemorrhoids, or piles, in fome recur monthly, in others only at the greater lunar influence about the equinoxes. 13. The periods of hcemoptoe fometimes obey folar influence, recurring early in the morning for {everal days ; and fometimes lunar periods, recurring monthly ; and fometimes depend on our hours of fleep. vSee Clafs I. 2. 1. 9. 14. Many of the firlt periods of epileptic fits obey the month- ly lunation with fome degree of accuracy j others recur only at the molt powerful lunations before the vernal equinox, and after the autumnal one ; but when the conftitution has gained a habit of relieving difagreeablc fenfations by this kind of exertion, the fit recurs from any flight caufe. 1 5. The attack of palfy and apoplexy are known to recur with great frequency about the equinoxes. 16. There are numerous initances of the effect: of the luna- tions upon the periods of infanity, whence the name of lunatic has been given to thofe afflicted with this difeafe. IV. The critical days, in which fevers are fuppofed to termi- nate, have employed the attention of medical philoiophers from the days of Hippocrates to the prefent time. In whatever part of a lunation a fever commences, which owes either its whole -caufe to folar and lunar influence, or to this in conjunction with other caufes ; it would feem, that the effect would be the great- eft at the full and new moon, as the tides rife higheit at thofe times, and would be the ieaft at the quadratures ; thus if a fe- ver-fit fhoulu commence at the new or full moon, occafioned by the folar and lunar attraction dim ini thing fome chemical af- finity of the particles of blood, and thence decreasing their ftimu- lus on our fanguiferous fyftem, as mentioned in Sect. XXXII. -6. this effect will daily decreafe for the iirft {even days, and will then increafe till about the fourteenth day, and will again decreafe till about the twenty-firit day, and increale again till the end of the lunation. If a fever-fit from the above can fhould commence on the feveath day after either lunation, t! reverfe of the above circumftances would happen. Now it probable, that thofe fevers, whofe crisis or terminations are in- fluenced Sect. XXXVL 4. 1. OF DISEASES. 3$9 fluenced by lunations, may begin at one or other of the above times, namely at the changes or quadratures •, though fufficient obfervations have not been made to afcertain this circumftance. Hence I conclude, that the fmall-pox and meafles have their critical days, not governed by the times required for certain chemical changes in the blood, which afFect or alter the ftimu- lus of the contagious rrfatter, but from the daily increafing or decreafing effect of this lunar link of catenation, as explained in Section XVII. 3.3. And as other fevers terminate mod fre- quently about the feventh, fourteenth, twenty-firft, or about the end of four weeks, when no medical affiftance has diflurbed their periods, I conclude, that thefe crifes, or terminations, are governed by periods of the lunations, though we are {till igno- rant of their manner of operation. In the diftincl: fmall-pox the veftiges of lunation are very ap- parent ; after inoculation a quarter of a lunation precedes the commencement of the fever, another quarter terminates with the complete eruption, another quarter with the complete matu- ration, and another quarter terminates the complete abforption ef a material now rendered inoffenfive to the constitution. SECT. #• DIGESTION, Sect. XXXVII. 2. 4 SECT. XXXVII. OF DIGESTION, SECRETION, NUTRITION. I. Cry ft a! s increafe by the greater attraction of their fides. Accre- tion by chemical precipitations , by welding, by prejjure, by aggluti- nation. II. Hunger, digeftion, why it cannot be imitated out of the body. Lacleals abforb by animal [election , or appetency. III. The glands and pores abforb nutritious particles by animal feleclion. Organic particles of Buff on. Nutrition applied at the time of elongation of fibres. Like inflammation. IV. It feems e after to have preferved animals than to reproduce them. Old age and death from inirr it ability. Three caufes of this. Original fibres of the organs cffenfe and mufcles unchanged. V. Art of producing long life. I. The larger cryftals of faline bodies may be conceived to arife from the combination of fmaller cryftals of the fame form, owing to the greater attractions of their fides than of their an- gles. Thus if eight cubes were floating in a fluid, whofe fric- tion or refinance is nothing, it is certain the fides of thefe cubes would attract each other ftronger than their angles 5 and hence that thefe eight fmaller cubes would to arrange themfelves as to produce one larger one. There are other means of chemical accretion, fuch as the de- pofitiens of diifolved calcareous or filiceous particles, as are fec*n in the formation of the fbakuftites of limeftone in Derby (hire, or of calcedone in Cornwall. Other means of adhefion are produ- ced by heat and prefiure, as in the welding of iron-bars ; and other means by fimple preflure, as in forcing two pieces of ca- outchou, or elaftic gum, to adhere ; and laftly, by the aggluti- nation of a third fub fiance penetrating the pores of the other two, as in the agglutination of wood by means of animal gluten. Though die ultimate particles of animal bodies are held togeth- er during life, as well as after death, by their fpecific attraction of cohefion, like all other matter ; yet it does not appear, that their original organization was produced by chemical laws, and their production and increafe mult therefore only be looked for' from the laws of animation. II. When the pain of hunger requires relief, certain parts of the material world, which furround us, when applied to our palates, excite into action the mufcles of deglutition ; and the material is fwallowed into the ftomach. Here the new aliment becomes mixed with certain animal fluids, and undergoes a chemical- Sect. XXXVII. 3. 1. SECRETION, Sec. 36; chemical procefs, termed digedion ; which, however, chemiftry has not yet learnt to imitate out of the bodies of living animals or vegetables. This procefs feems very fimilar to the facchanne procefs in the lobes of farinaceous feeds, as of barley, when it begins to germinate ; except that, along with the fugar, oil and mucilage are alfo produced •, which form the chyle ot ani- mals, which is very fimilar to their milk. The reafon, I imagine, why this chyle-making, or facchanne procefs, has not yet been imitated by chemical operations, is owing to the materials being in fuch a fituation in reipecr. to warmth, moifture, and motion } that they will immediately change into the vinous or acetous fermentation ; except the new fugar be abforbed by the numerous lacteal or lymphatic veflels, as foon as it is produced ; which is not eafy to imitate in the laboratory* Thefe lacteal vefTels have mouths, which are irritated into ac- tion by the ftimulus of the fluid which furrounds them ; and by animal felection, or appetency, they abforb fuch part of the ilu- id as is agreeable to their palate $ thofe parts, for initance, which are already converted into chyle, before they have time to undergo another change by a vinous or acetous fermentation. This animal abforption of fluid is aimed vifibie to the naked eye in the action of the puncTa lachrymalia ; which imbibe the tears from the eye, and di (charge them again into the noilriis. III. The arteries conltitute another refervoir of a changeful fluid j from which, after its recent oxygenation in the lungs, a further animal felection of various fluids is abforbed by the nu- ■^merous glands ; thefe felect their refpective fluids from the blood, which is perpetually undergoing a chemical change ; but the felection by thefe glands, like that of the lacteais, which open their mouths into the digetting aliment in the ftomuch, is from animal appetency, not from chemical affinity ; fecretion cannot therefore be imitated in the laboratory, as it confifts in a felection of part of a fluid during the chemical change of that fluid. The mouths of the lacteais, and lymphatics, and the ultimate terminations of the glands, are finer than can eafily be conceived ; yet it is probable, that the pores, or interfiUces of the parts, or coats, which conftitute thefe ultimate vehcis, may ftill have greater tenuity ; and that thefe pores from the above anai)-.- muft poiTefs a fimilar power of irritability, and abforb by their living energy the particles of fluid adapted to their purposes, whether to rephice the parts abraded or difTolved, or to ejongatd and enlarge themfelves. Not only every kind of gland is ihus endued with its peculiar appetency, and felecU the material Vol. I. Y y agreeable 3^ DIGESTION, Sect. XXXVII. 3. r, agreeable to its tafte from the blood, but every individual pore: acquires by animal felection the material, which it wants ; and thus nutrition feems to be performed in a manner fo fimilar to fecretion ; that they only differ in the one retaining, and the other parting again with the particles, which they have fele&ed from the blood. They may, indeed, differ in another circumftance •, that in nutrition certain particles of the circulating blood, which have not previouily been ufed in the fyftem, are embraced, and form a folid part of the animal. Whereas in fome of the fecretions, thofe particle3 appear to be imbibed by the glands, which have already been ufed in the fyftem, and probably abraded or de- tached from it into the circulation : thefe are depofited in refer- voirs for future ufe, as bile and mucus ; or excluded for other purpofes, as femen and tears •, or-evacuated fimply as feces and urine. And it mould be obferved, that all thefe fecretions are* produced from their glands, in a very dilute ftate, mingled, I be- lieve, with mucus diffolved in water ; which is in part re-ab- forbed from trie refervoirs of the glands, or from the cells or furfaces of the body, that no unneceffary wafte of animal mat- ter may occur ; which accounts for the urinary bladders of fifli, which would othervvife appear to be unneceffary, according to the observation of Munro. This way of accounting for nutrition from ftimulus, and the confequent animal felection of particles, is much more analo- ' gous to other phenomena of the animal microcofm, than by having recourfe to the microfcopic animalcula, or organic par- ticles of Buffon and Needham ; which being already compound- ed muft themfelves require nutritive particles to continue their own existence. And muft be liable to undergo a change by our di-> , '.live or fecreiory organs ; otherwife mankind would foon refer' ble by their theory the animals, which they feed upon. He, who is nourished by beef cr venifon, would in time become horned ; and he, who feeds on pork or bacon, would gnin a nofe proper for rooting into the earth, as well as for the perception of odours. The whole animal fyftem may be confidered as confiding of the extremities of the nerves, or of having been produced from them ; ii we except perhaps the medullary part of the brain refiding in the head and fpine, and in the trunks of the nerves. The fe mities of the nerves are either of thofe of locomotion, are termed mufcular fibres ; or of thole of fenfation, which cenftitute tl mediate organs of fenfe, and which have alfo their peculiar motions. Now as the fibres, which confti- tute the bones and membranes, poffefled originally fenfation and motion ; and are again topollefs them, when they become inflamed ; Sect. XXXVII. 3. 1. SECRETION, &c. 363 inflamed •, it follows, that thofe were, when firH: formed, ap- pendages to the nerves of fenfation or locomotion, or were formed from them. And that hence all thefe folid parts of the body, as they have originally confided of extremities of nerves, require an appofition of nutritive particles of a fimilar kind, .contrary to the opinion of Buffon and Needham above recited. 'JUaftly, as all thefe filaments have pofTerTed, or do pofiefs, the power of contraction, and of consequent inenion or elongation ; it feems probable, that the nutritive particles are applied during their times of elongation \ v/hen their original conflituent par- ticles are removed to a greater diftance from each other. For each mufcular or fenfual fibre may be confidered as a row or firing of beads ; which approach, when m contraction, and re- cede during its reft or elongation j and our daily experience ihews us, that great action emaciates the fyftem, and that it is repaired during reft. Something like this is feen out of the body 3 for if a hair, or a fingle untwifted fibre of flax or filk, be foaked in water j it be- comes longer and thicker by the water, which is abforbed into its pores. Now if a hair could be fuppofed to be thus immerfed in a folution of particles fimilar to thofe, which compofe it ; one may imagine, that it might be thus increafed in weight and magnitude ; as the particles of oak-bark increafe the fubftance of the hides of beafts in the procefs of making leather. I men- tion thefe not as philofophic analogies, but as fimilies to facili- tate our ideas, how an accretion of parts may be effected by animal appetences, or felections, in a manner fomewhat fimilar to mechanical or chemical attractions. If thofe new particles of matter, previoufly prepared by di- geftion and fanguification, only fupply the places of thofe, which have been abraded by the actions of the fyftem, it is properly- termed nutrition. If they are applied to the extremities of the nervous fibrils, or in fuch quantity as to increafe the length or craffitude of them, the body becomes at the fame time enlarged, and its growth is increafed, as well as its deficiencies repaired. In this laft cafe fomething more than a fimple appofition or felection of particles feems to be neceffary ; as many parts of the fyftem during its growth are caufed to recede from thofe, with which they were before in contact ; as the ends of the bones, or cartilages, recede from each other, as their growth advances : this procefs refembies inflammation, as appears in ophthalmy, or in the production of new flefn in ulcers, where old vefTels are enlarged, and new ones produced j and like that is attended with fenfation. In this fituation the vefTels become iteftended with blood, and acquire greater fenfibility, and may th u$ 364 DIGESTION, Sect. XXXVII. 4. t; thus be compared to the erection of the penis, or of the nipples ot the breafts of women ; while new particles become added at the fame time ; as in the procefs of nutrition above defcribed. When only the natural grawth of the various parts of the body is produced, a plealurable fenfation attends it, as in youth, and perhaps in thole, who are in the progrefs of becoming fat. "When an unnatural growth is the confequence, as in inflam- matory dileaies, a painful fenfation attends the enlargement of the fyitem. IV. This appoHtion of new parts, as the old ones difappear, felecled from the aliment we take, firfl enlarges and ftrength- ens our bodies for twenty years ; for another twenty years it keeps us in health and vigour, and adds ftrength and folidity to the fytlem, and then gradually ceafes to nouriih us properly ; and for another twenty years we gradually fink into decay, and finally ceafe to act, and to exift. On confidering this fubjecr. one mould have imagined at firfl view, that it might have been eafier for nature to have fup- ported her progeny for ever in health and life, than to have per- petually reproduced them by the wonderful and myfterious procefs of generation. But it feems our bodies by long habit ceafe to obey the ftimulus of the aliment, which {hould fupport us. After we have acquired our height and folidity we make no more new parts, and the fyilem obeys the irritations, fen- fations, volitions, and afTociations, with lefs and lefs energy, till the whole finks into inaction. Three caufes may confpire to render our nerves lefs excitable, which have been already mentioned. 1. If a ftimulus be greater than natural, it produces too great an exertion of the ftimulated organ, and in confequence exhaufts the fpirit of animation ; and the moving organ ceafes to acl:, even though the ftimulus be continued. And though reft will recruit this exhauftion, yet fome degree of permanent injury remains, as is evident after ex- pofing the eyes long to too ftrong a light. 2. If excitations weaker than natural be applied, fo as not to excite the organ into action, (as when fmall dofes of aloes or rhubarb are ex- hibited,) they may be gradually increafed, without exciting the organ into aclion ; which wili thus acquire a habit of difobedi- ence to the ftimulus ; thus by increasing the dofe by degrees, great quantities of opium or wine may be taken without intoxi- cation. See Seel, XII. 3. 1. 3. Another mode, by which life is gradually undermined, is when irritative motions continue to be produced in confequence of ftimulus, but are not fucceeded by fenfation ; hence the ftimulus of contagious matter is not capable of producing fever Sect. XXXVII. 5. 1. SECRETION, Sec. 365 a fecond time, becaufe it is not fucceeded by fenfation. Sec Se£t. XII. 3. 6. And hence, owing to the want of the gener- al pleaiurable fenfation, which ought to attend digeftion and glandular fecretion, an irkfomenefs of life enfues ; and, where this is in greater excefs, the melancholy of old age occurs, with torpor or debility. /From hence I conclude, that it is probable that the fibrillas, ,or moving filaments at the extremities of the nerves of fenfe, and the .fibres which conllitute the mufcles (which are perhaps the only parts of the fyftem that are endued with contractile life) are not changed, as we advance in years, like the other parts of the body ; bat only enlarged or elongated with our growth 5 and in confequence they become lefs and lefs excitable into ac- tion. Whence, inftead of gradually changing the old animal, the generation of a totally new one becomes necefiary with un- diminiihed excitability ; which many years will continue to ac- quire new parts, or new folidity, and then lofing its excitability in time, periih like its parent. V. From this idea the art of preferving long health and life maybe deduced; which muft confift in ufing no greater ftimu- lus, whether of the quantity or kind of our food and drink, or of external circum (lances, fuch as heat, and exercife, and wake- fulnefs, than is fufficient to preferve us in vigour ; and gradual- ly, as we grow old to increafe the ftimulus of our aliment, as the inirritability of our fyftem increafes. The debilitating effects afcribed by the poet Martial to the .•excefiive ufe of warm bathing in Italy, may with equal propriety be applied to the warm rooms of England ; which, with the general excefiive ftimulus of fpirituous or fermented liquors, and in fome inftances of immoderate venery, contribute to fhorttn our lives. Balnea, win a, Venus > corrumpunt corpora nojfra: At faciunt ft animations, new veffels are form- ed. Mules partake of the forms of both parents. Hair and nails grow by elongation, not by difiention. 3. Organic particles of Buff on. IV. 1. Rudiment of the embryon a fimpfe living f la- ment, becomes a living ring, and then a living tube. 2. It ac- quires new irritabilities, and fenfibilities with new organizations, as in wounded f flails, pofpi, moths, gnats, tad-poles. Hence new parts are acquired by addition not by difiention. 3. All parts of the body grow if not confined. 4. Fetufes deficient at their ex- tremities, or have a duplicature of parts. Monfirous births. Double parts of vegetables. 5. Mules cannot be formed by dif- tention of the feminal ens . 6. Families of animals from a mix-' ture of their orders. Mules imperfect. 7. Animal appetency like chemical affinity. Vis fabricatrix and medicatrix of nature. 8. Th >ie 3-74 GENERATION. Sect. XXXIX. 8. The changes of animals before and after nativity. Similarity of their f e. Changes in them from luj}^ hunger % ami c , - r. All warm-blooded animals derived from one li '•• • ■ \g filament . Cold^Mooded animals t ?a feels, worms , vegetables, derived alfo from one (iving filament. Male animals have teats. AI ale pigeon gives milk. The world it e fe cfcaufes. A fl ate of probation and refponfibility. V. I. Efficient caufe of the colours of I'i, ds' eggs, and of hair and feathers ', which become'whiie in fuowy countries. Imagination of the female colours the egg. Ideas or motions of the retina imitated by the extremities of the nerves of touchy or fete mucsfunti %. L bent fupplied by the female of three kinds. Her imagination can only ajfeel the firfi kind. ules hovj produced) and mulattoes. Organs of reproduction why deficient in mules. Eg<^s with double yolks. VI. I. Various fe- c ret ions produced by the extremities of the veffels, as in the glands. Contagious matter. Many glands affected by pleafurable ideas, 1. thfe which fee ret e the feme n. 2. S/iails and worms are her- maphrodite, yet cannot impregnate themfelves. Final caufe of y. 3. The imagination of the male forms the J ex. Ideas, or motions of the nerves ofvifion or of touch, are imitated by the ulti- mate extremities of the glands of the tejles, which mark the f ex. This effect of the imagination belongs only to the male. The fex of . . yon is not owing to accident. 4. Cattfes of the changes in . from hm .on as in monjlers. From the male. From the female. 5. M carriages from fear. 6. Fewer of the imagination cfthe male over the colour ', form, and fex of the prog- cr An tnjiance qf. 7. jttj of generation accompanied with ideas of the male or female 'f or m. Art of begetting beautiful chil- dren of either fex. VII. Recapitulation. VIII. r. Appendix. Buds are individuals. Conjtjl of pi u inula cnudex and radicle, livery part of the caudex can germinate. A triple tree by ingraft- ment. A lateral vegetable mule produced by three parents. Gon- fervafontindlis. 2. Lateral propagation of polypus, and hydra >torea. The halves of two polypi made to unite. Ingraftment of vegetables. Lateral mule. 3. New bud of a doubly ingrafted tree has thn e hinds of caudex. Triple mule produced from vari- ous parts of the parent tree. 4. Earthworms cut afunder gener- ate a nezv head, and a new tail. So the caudexes cfthe buds of ees. Thi -yon not formed at the fame time. 5. Parts caudex of the new bud are fecreted from correfpondent rts of lie parent bud, and unite beneath the cuticle. livery . 'ex can germinate. Thefe pew buds refmble the part cf : h, where i. Lateral mule from many its. If a triple fexual mule ? 6. Gravitation, chemical affmiv', electricity ^ m fm. Fewer to attract1. Aptitude to be Sect. XXXIX. GENERATION. 37^' be attracted. A magnet pffiffes power to atiracl^ iron an aptitude to be attracted. So of electrified bodies, and chemical affinities. Or two bodies may reciprocally attract each other. 7. Union of animal with inanimate matter. Union of tivs living particles. The animal fenfe poffefTes appetency to unite, the inanimate materi- al pcjjejfes aptitude to be united. Vitality of the blood. Fibrils with appetencies, molecules with prbperfiities. 8. Fibrils with formative appetencies. Molecule.'; with formative propenfiics. Like Jingle and double affinities. Paffions of hunger and cf love. Thirjl. Suckling children. Mode of lateral propagation, p. Superfluous vital particles produced in the blood. Secreted by fix- ual glands. Combine beneath the cuticle of trees. Acquire new appetencies," and form fecondary parts of the embryon. So the paffwn for generation, and de fire for animal food, and the new at- tractions cf bodies chemically combined. New molecules are form- ed by the fexual glands at puberty, and in the pectoral cues. 10. Different fibrils and molecules are detached from different parts of the parent caudex to form the filial one : fo in the fexual propa- gation of vegetables : and by their combination produce an embry- on, and acquire neiu appetencies and form fecondary parts, as in dioecious -flowers. 11. Threefold lateral mules. So fexual mules refemble parts of their parents according to the combinations of the fibrils and molecules, and produce fecondary parts, otherwfe they would refemble the father only. Epigram from Martial. IX. I. Various parts of the new embryon produced at the fame time. Organized bodies too large to befecreted. Primary and fecondary formation of parts of the fetus. M. Buff oris theory differs front this. Moles and monfirous births. An embryon is not an in- dividual, till the nerves unite in the brain. 2. The brain and heart generated at the fame time. 3. Orga?iic particles too largr to pafs the glands and capillaries. Not fo the formative particles. Hence the latter cannot combine in the blood. 4. Formative par- ticles do not combine in the receptacles of the fexual glands, asthofe of the male differ from thofs of the females Not jo in Buff on s theory. 5. The whole embryon not produced at the fame time. Primary and fecondary parts. Secondary formation of the caudex of buds, of diffevered earth worms, of the legs of crabs, ej human teeth, and of a thumb. X. I . Solitary lateral generation, and folitary internal generation. Animalized particles of primary combination, are fecreted, combine, and form primary organizations. The caudex gem/me produces fecondary parts, and commences its formation in J'everal places at the fame time. Refcmbles the parent more than a fexual progeny. ci he polypus and hydra. 2. Solita- ry internal generation of aphis, tenia, aclinia, volvox, produces a viviparous of spring, not an oviparous one. Difference of lateral mid 37^ Feneration. Sect, xxxdl and internal generation. 3. Hermaphrodite fexual generation in mojl fawers, and fome infefits. Summit-bulbs of fame vegeta- bles are a fexral progeny. Sexual organs in hermaphrodites are feparatc, but /ecrete I dine and feminine formative particles from the fame niafs of blood.' IVhy fecdling apple-trees fometimes re ftrnble the parent ', foretimes not. Number of fpeci.es incrcafed by reciprocal generation. 4. /;/ fniple fexual generation the m.fcu- line and feminine fecretions are from different maffes of blood. Thefe animals were originally hermaphrodites. The mode of the produclion of the new enibryon, Secretion differs from nutrition. New embryon begins in move parls than one. Acquires new :ip- petencieSf and fabricates fee .'parts. Sexual organs arefecon- dary parts, not primary ones. So is the 'difference of the male and female forms. V, \etable and animal fecondary productions. 5. Seeds. Eggs. Spawn differs from eggs, as it enlarges along ivith the embrvon like the membranes of the fetus in ntero. XI. 1. In- animate crfldls. Animated organization. Microfcopic animal- cula from flagnation of vegetable and animal fluids. Do not generate. 2. Second kind of animal production commences in more points than one : not like microfcopic animals ; as truffles, fungi, polypi, hydra. 3. Other vegetables are hermaphrodite, but both their fexual glands fecreie from the fame mafs of blond. 4. Other -aege tables have acquired feparatefexes, and J ecrete the prolific fiu- h from different nlajfes of blood. The embryon begins in more points in the more complicated animals. The primary parts fabri- cate fecondiiry ones, as in the cljjsdioeciaofvcget.'Jyie^ and m fexu- al ayimals. Nature is yet in her infancy. c. Spontaneous pro- duction of microfcopic animalcules. Is fimilar to actual 'genera* 'ion. The firfl animalcules generate others, and improve. Seedling tu- lip-root. Aphis. Immutable laws imprefjed on matter. XII. Conclufon. Of caufe and effccl. Ihe atomic philofophy leads t§ a firfl caufe. I. The ingenious Dr. Hartley in his work on marl, and feme other philofophers, have been of opinion, that our immortal part acquires during this life certain habits of aftion or of fenti- ment, which become for ever indiilolubJe, continuing after death in a future itate of exidence ; and add, that if thefe habits are of the malevolent kind, they muft rendtr the poffjflbr miferable even in Heaven. I would apply this ingenious idea to the gener- ation or production of the embryon, or new animal, which •rakes \o much of the form and propensities of the parent. Owing to the imperfection of language the offspring is termed ■tew animal, but is in truth a branch or elongation of the par- ent : (tnce a part of the embryon-animal is, or was, a part of the parent ; Sect. XXXIX. i. i. GENERATION. 3l1 .parent; and therefore in ftrict language it cannot be faid^to be entirely new at the time of its prod uct ion ; and therefore it may retain fome of the habits of the parent- fy Item. At the earlieft period of its exiftence the embryon, as fecreted from the blood of the male, would feem to confift of a living? filament with certain capabilities of irritation, fenfation, voli- tion, and afTociation ; and alio with fome acquired habits or propenfities peculiar to the parent : the former of thefe are in Common with other animate ; the latter feem to diftinguifh or produce the kind of animal, whether man or quadruped, with the fimilarity of feature or form to the parent. It is difficult to be conceived, that a living entity can be feparated or produced from the blood by the action of a gland ; and which fhall after- wards become an animal Similar to that in whofe vefTels it is formed ; even though we mould fuppofe with fome modern theorifts, that the blood is alive ; yet every other hypothecs con- cerning generation refts on principles (till more difficult to our comprehenfion. At the time of procreation this fpeck of entity is received in- to an appropriated nidus, in which it mud acquire two circum- ftances neceflary to its life and growth ; one of thefe is food or fuftenance, which is to be received by the abforbent mouths of its velfels ; and the other is that part of atmofpherical air, or of water, which by the new chemiftry is termed oxygene, and which affects the blood by palling through the coats of the vef- fels which contain it. The fluid furrounding the embryon in its new habitation, which is called liquor amnii, fupplies it with nourifhment •, and as fome air cannot but be introduced into the Uterus along with a new embryon, it would feem that this {we fluid would for a fhort time, fuppofe for a few hours, fupply likewife a fufficient quantity of the oxygene for its immediate exiftence. On this account the vegetable impregnation of aquatic plants is performed in the air ; and it is probable" that the honey-cup or nectary of vegetables requires to be open to the air, that the anthers and ftigmas of the flower may have food of a more oxygenated kind than the common vegetable fap-juice. On the introduction of this primordium of entity into the uterus the irritation of the liquor amnii, which furrounds it, ex- cites the abforbent mouths of the new vefTels into action ; they J drink up a part of it, and a pleafurable fenfation accompanies I this new action ; at the fame time the chemical affinity of the oxygene acts through the vefTels of the rubefcent blood •, and a {previous want, or difagreeable fenfation, is relieved by this jprocefs. Vol, I. A a a A$ 373 , GENERATION. Sect. XXXIX. i .r> As the want of this oxygenation of the blood is perpetual, (as appears from the incefTant neceflity of breathing by lungs or gills,) the veflels become extended by the efforts of pain or defire to feek this neceflary object of oxygenation, and to remove the difagreeable fenfation, which that want occafions. At the fame time new particles of matter are abforbed, or applied to thefe extended veflels, and they become permanently elongated, as the fluid in contact with them foon lofesthe oxygenous part, which it at fir ft poflefled, which was owing to the introduction of air along with the embryon. Thefe new blood-veflels approach the fides of the uterus, and penetrate with their fine terminations into the veflels of the mother ; or adhere to them, acquiring oxygene through their coats from the palling currents of the ar- terial blood of the mother. See Seel. XXXVIIL 2. This attachment of the placental veflels to the internal fide of the uterus by their own proper efforts appears further illuffrated by the many inftances of extra-uterine fetufes, which have thus attached or inferted their veflels into the peritoneum ; or on the vifecra, exactly in the fame manner as they naturally infert or attach them to the uterus. The abforbent veflels of the embryon continue to drink up nourifhment from the fluid in which they fwim, or liquor am- nii; and which at firft needs no previous digeftive preparation \ but which, when the whole apparatus of digeftion becomes com- plete, is fvvailowed by the mouth into the ftomach, and being mixed with faliva, gaftric juice, bile, pancreatic juice, and mucus of the inteflincs, becomes digefted, and leaves a recrement, which produces the firlt feces of the infant, called meconium. The liquor amnii is fecreted into the uterus, as the fetus re- quires it, and may probably be produced by the irritation of the fetus as an extraneous body \ fmce a fimilar fluid is acquired from the peritoneum in cafes of extra-uterine geftation. The young caterpillars of the gad-fly placed in the fkins of cows, and the young of the ichneumon-fly placed in the backs of the cater- pillars on cabbages, feem to produce their nourifhment by their irritating the tides of their nidus. A vegetable fecrction and concretion are thus produced on oak-leaves bv the gall-infect, and by the cynips in the bctieguar of the rofc ; and by rhe young grafshopper on many plants, by which the animal furrounds it- ielf with froth. But in nc circumftance is extra-uterine gefta- .1 fo exactly refembled as by the eggs of a fly, which are de- posited in the frontal fir.us of fheep and calves. Thefe eggs float in fome ounces cf Arid collected in a thin pellicle or hydatid. This bag cf fluid compiefles the optic nerve on one fide, by which the viflon being lefs difttnet in that eye, the animal turns in per- petual Sect. XXXIX. i.i. GENERATION. ' 379 petual circles towards the fide affected, in order to get a more accurate view of objects ; for the fame reafon as in fquiriting the affected eye is turned away from the object: contemplated. Sheep in the warm months keep their nofes clofe to the ground .to prevent this fly from fo readily getting into their noflrils. The liquor amnii is fecreted into the womb as it is required, not only in reipect to quantity, but, as the digeftive powers of the fetus become formed, this fluid becomes of a different confid- ence and quality, till it is exchanged for milk after nativity. Mailer. Phyfiol. V. I. In the ^gg the white part, which is analogous to the liquor amnii of quadrupeds, confifts of two diftinct parts j one of which is more vifcid, and probably more difficult of digeftion, and more nutritive than the other ; and this latter is ufed in the laft week of incubation. The yolk of the egg isa (till ftronger or more nutritive fluid, which is drawn up into the bowels of the chick juft at its exclufion from the fhell, and ferves it for nourifhment for a day or two, till it is able to digeft, and has learnt to choofe the harder feeds or grains, which are to afford it fuftenance. Nothing analogous to this yolk is found in the fetus of lactiferous animals, as the milk is another nutritive fluid ready prepared for the young progeny; it is alfo a curious circumftance, that the firft milk of female ani- mals after parturition is much thicker, like the yolk of eggy and much more coagulable, than that which is fecreted after a few days, when the digeflive powers of the offspring are become ftronger. The yolk therefore is not neceffary to the fpawn of fifh, the eggs of infects, or for the feeds of vegetables ; as their embry- ons have probably their food prefented to them as foon as they are excluded from their fhells, or have extended their roots. Whence it happens that fome infects produce a living progeny in the fpring and fummer, and eggs in the autumn ; and fome vegetables have living roots or buds produced in the place of feeds, as the polygonum viviparum, and magical onions. Sec Eotanic Garden, p. ii. art. Anthoxanthum. There feems however to be a refervoir of nutriment prepared for fome feeds befides their cotyledons or feed-leaves, which may be fuppofed in fome meafure analogous to the yolk of the egg. Such are the faccharine juices of apples, grapes, and other fruits, which fupply nutrition to the feeds after they fall on the ground. And fuch is the milky juice in the centre of the cocoa-nut, and part of the kernel of it ; the fame I fuppofe of all other monoco- tyledon feeds, as of the palms, grades, and lilies. The milky juice in the centre of the cocoa-nut feems curioufly to refemble the chyle of animals, as it contains oil difFuted with mucilage zn4. $U GENERATION. Sect. XXXIX. 2. 1. and fugar, whence arifes its white colour •, whereas the chyle or fap-juice of vegetables, which exudes from wounds of birch or maple-trees in the vernal months, is tranfparent, and confiftsoi.- ly of fugar and mucilage, and in this circunallance diifers from the chyle of animals. II. 1. The procefs of generation is ftill involved in impene- trable obfcurity, conjectures may neverthelefs be formed con- cerning fome of its circumilances. Firft, the eggs of fi(h and frogs are impregnated, after they leave the body of the female ; becaufe they are depofited in a fluid, and are not therefore covered with a hard f hell. It is however remarkable, that neither frogs nor fiih will part with their fpawn without the prefence of the male ; on which account female carp and gold-fifh in fmall ponds, where there are no males, frequently die from the idiftention of their growing fpawn. 2. The eggs of fowls, which are laid without being impregnated, are feen to contain only the yolk and white, which are evidently the food or fuf- tenance for the future chick. 3. As the cicatricula of thefe eggs is given by the cock, and is evidently the rudiment of the new animal j we may conclude, that the embryon is produced by the male, and the proper food and nidus by the female. Foy if the female be fuppofed to form an equal part of the embryon, why fhould fhe form the whole of the apparatus for nutriment and for oxygenation ? The male in many animals is larger, ftronger, and digefls more food than the female, and therefore fhould contribute as much or more towards the reproduction of the fpecies ; but if he contributes only half the embryon and none of the apparatus for fuftenance and oxygenation, the di- vifion is unequal ; the ftrength of the male, and his confump- tion of food are too great for the effect, compared with that of the female, which is contrary to the ufual courfe of nature. It has been fuppofed by fome inquirers into the procefs of generation, that the male femen in many animals could not come into contact with the ovum of the female, and they have hence fuppofed, that an aerial or ethereal emanation from the femen virile might ferve the purpofe of flimulating into life the ovum muliebre, becaufe in. the vegetable ftigma of fome flowers no vcflels have been feen to receive and tranfmit the burfting an-» ther-duft ; and becaufe it is not pofllble, that the ejaculatio feminis in quadrupeds could fend it through the fallopian tubes to the veficles of the ovaria. In refpect to the analogies from other animals, ift, It may be obferved, that in the generation of frogs, it is well known, that the male fperm is efTufed in contact with the female fpawn, as it leaves her body, and that in flfh the male fperm is likewife efTufed Sect. XXXIX. 2. 1. GENERATION. 3U cfFufed on the female fpawn after its production. 2d. In refpect to vegetables, it rouft be recollected, that their vefiels are fo mi- nute in diameter, that they have not in general been of fufficient fize to be injected by coloured fluids ; and are not thence fo vifible by microscopes as thofe of animals, and that it is probable, thole of the ftigma ox piitillum of flowers, which are defigned to abforb the Solution of the anther-duil, which adheres to the moifl ftigma, may be always empty, or have their mouths doted* except when they are Simulated into action by the anther-duft, and may thence more eafily efcape observation. Nor do I know, that any one has endeavoured to detect -thefe vefFels by experi- ments with coloured liquids applied along with the male farina on the ftigma for its abforption, or by directing the piftillum as in its recent or dry ftate, or by obServing it in a ftate of charcoal. In regard to quadrupeds, Dr. Haighton has fnewn by a num- ber of curious experiments on rabbits, publifhed in the Philo- Soph. Tranfact. for the year 1797, that the male femen does not permeate the fallopian tubes, and confequently never arrives at the female ova, either in a liquid or aerial ftate ; but that it is by the ftimulus of the femen in the neck of the uterus ; that the veficles of the ovaria fwell, and difcharge the material, which has been called an ovum /though it does not pofTefs a diftinguifh- able form ; and that this is acquired and carried into the uterus by the periftaltic motions of the fallopian tubes, Some hours af- ter copulation. Here I fuppofe it finds the male femen, and that thus the new animal produced by the fecretion of the male jfinds correfponding nutriment and fituation in the female in all Sexual progeny. But that no female apparatus is required in the production of the buds of trees, or in the adherent fetus of the polypus, or of the coral-infects. In objection to this theory of generation it may be faid, if the animalcuia in femine, as feen by the microfcope, be all of then*, rudiments of homunculi, when but one of them can find a nidus, what a wafte nature has made of her productions ? I do not ak- fert that thefe moving particles, vifible by the microfcope, are homunciones; perhaps they maybe the creatures of ftagnation or putridity, or perhaps no creatures at all j but if they are fup- pofed to be rudiments of homunculi, or embryons, fuch a pro- fufion of them corresponds with the general efforts of nature to provide for the continuance of her fpecies of animals. Every individual tree produces innumerable feeds, and every individual fifh innumerable fpawn, in fuch inconceivable abundance as v/ould in a fnort fpace of time crowd the earth and ocean with inhabitants; and thefe are much more perfect animals than the ammaleuia in femine can be fuppofed to be, and pcrifh in un- counted 382 GENERATION. Shct. XXXIX. 2. 2. counted millions. This argument only (hews, that the produc- tions.of nature are governed by general laws ; and that by a wife fuperfluity of provifion (he has enfured their continuance. 2. That the embryon is fecreted or produced by the male, and not by the conjunction of fluids from both male and female, appears from the analogy of vegetable feeds. In the large flow- ers, as the tulip, there is no fimilarity of apparatus between the anthers and the ftigma : the feed is produced according to the obfervations of Spallanzani long before the flowers open, and in confecfuence long before it can be impregnated, like the egg in the pullet. And after the prolific dull is thed on the ftigma, the feed becomes coagulated in one point firft, like the cicatricu- la of the impregnated egg. See Botanic Garden, Part I. addi- tional note 38. Now in thefe fimple products of nature, if the female contributed to produce the new embryon equally with the male, there would probably have been fome vifible fimilarity of parts for this purpofe, befides thofe necefTary for the nidus and fuftenance of the new progeny. Befides in many flowers the males are more numerous than the females, or than the fepa- rate uterine cells in their germs, which would (hew, that the of- fice of the male was at lead: as important as that of the female ; whereas if the male, befides producing the egg or feed, was to produce an equal part of the embryon, the office of reproduction would be unequally divided between them. Add to this, that in the mod: fimple kind of vegetable repro- duction, I mean the buds of trees, which are the viviparous offspring, the leaf is evidently the parent of the bud, which rifes in its bofom, according to the obfervation of Linnxus. This leaf confifls of abforbcnt vefTels, and pulmonary ones, to obtain its nutriment, and to impregnate it with oxygene. This fimple piece of living organization is alfo furnifhed with a power of re- production; and as the new offspring is thus fupported adhering to its father, it needs no mother to fupply it with a nidus, and nutriment, and oxygenation ; and hence no female leaf has cxiftence. I did conceive that the vefTels between the bud and the leaf communicated or inofculated ; and that the bud was thus ferved with vegetable blood, that is, with both nutriment and oxygena- tion, till the death of the parent-leaf in autumn. And that in is refpecl: it differed from the fetus of viviparous animals. But, fince the former editions of this work were publifhed> I ,/e been induced to change that opinion ; as on difTecling the i of the horfe-chefnur, aefculus hippoc3itanum, as mentioned 'ow, no communication of vefTels between the leaf and the bud I n it;> bofom could be perceived, fo that it is more probably Sect. XXXIX. 2. 2, GENERATION. 383 probably nourished by abforbing the fluid, with which it is fur- rounded, like the fetus of animals, as (hewn in my work on vegetation, termed Phytologia. Seel. VII. 1. 2. Secondly, I conceive that then the bark-veffels belonging to the dead leaf, and in which I fuppofe a kind of manna to have been depofited, be- come now the placental veffels, if they may be fo called, of the new bud. From the vernal fap thus produced of one fugar-ma- ple-treein New-York and in Pennfylvania, five or fix pounds of good fugar may be made annually without deflroying the tree. Account of maple-fugar by B. Rufh. London, Phillips. (See Botanic Garden, Part I. additional note on vegetable placenta- tion.) Thefe veiTels, when the warmth of the vernal fun hatches the young bud, ferve it with a faccharine nutriment, till it acquires leaves of its own, and (hoots a new fyftem of abforbents down the bark and root of the tree, juft a3 the farinaceous or oily mat- ter in feeds, and the faccharine matter in fruits, ferve their em- bryons with nutriment, till they acquire leaves and roots. This analogy is as forcible in fo obfeure a fubjecT:, as it is curious, and may in large buds, as of the horfe-chefnut, be almoil feen by the naked eye ; if with a penknife the remaining rudiment of the laft year's leaf, and of the new bud in its bofom, be cut away llice by flice. The feven ribs of the laft year's leaf will be feen to have arifen from the pith in feven diftincl: points making a curve ; and the new bud to have been produced in their centre, and to have pierced the alburnum and cortex, and grown with- out the afliftance of a mother. A fimilar procefs may be feen on difTecling a tulip-root in winter j the leaves, which enclofed the laft year's flower-ftalk, were not neceflary for the flower ; but each of thefe was the father of a new bud, which may be now found at its bafe ; and which, as it adheres to the parent, required no mother. This paternal offspring of vegetables, I mean their buds and bulbs, is attended with a very curious cireumftance ; and that is, that they exact ly refembie their parents, as is obfervable in grafting fruit trees, and in propagating flower-roots ; whereas the feminal offspring of plants, being iupplied with nutriment by the mother, is liable to perpetual variation. Thus alio in the vegetable clafs dioecia, where the male flowers are produced on one tree, and the female ones on another ; the buds of the male trees uniformly produce either male flowers, or other buds fimi- lar to themfelves ; and the buds of the female trees produce either female flowers, or other buds fimilar to themfelves j whereas the feeds of thefe trees produce either male or female plants. From this analogy of the production of vegetable bud-- without 3^4 GENERATION. Sect. XXXIX. 2. without a mother, I contend that the mother does not contribute to the formation of the living ens in animal generation, but is neceffary only for fupplying its nutriment and oxygenation. There is another vegetable fact publiflied by M. Koelreuter, which he calls " a complete metamorphofis of one natural {pe- des of plants into another," which (hews, that in feeds as well as in buds, the embrycri proceeds from the male parent, though the form of the fubfeq'uent mature plant is in part dependent on the female. M. Koelreuter impregnated a ftigma of the nico- tiana ruftica with the farina of the nicotiana paniculata, and cb- ttrned prolific feeds from it. With the plants which fprung from thefe feeds, he repeated the experiment, impregnating them with the farina of the nicotiana paniculata. As the mule plants which he thus produced were prolific, he continued to impreg- nate them for many generations with the farina of the nicotiana paniculata, and they became more and more like the male par- ent, till he at length obtained fix plants in every refpect perfect- ly fimilar to the nicotiana paniculata ; and in no refpect refem- bling their female parent the nicotiana ruftica. Blumenbach oil Generation. 3. It is probable that the infects, which are faid to require but one impregnation for fix generations, as the aphis (fee Amenit. Academ.) produce their progeny in the manner above defcribed, that is, without a mother, and not without a father •, and thu* experience a lucina fine concubitu. Thofe who have attended to the habits of the polypus, which is found in the ftagnant wa- ter of our ditches in July, a^rm, that the young ones Branch out from the fide of the parent like the buds of trees, and after a time feparate themfelves from them. This is fo analogous to the manner in which the buds of trees appear to be produced, that thefe polypi may be confidered as all male animals, produ- cing embryons, which require no mother to fupply them with a nidus, or with nutriment, and oxygenation. This lateral or lineal generation of plants, not only obtains in the buds of trees, which continue to adhere to them, but beautifully feen in the wires of knot-grafs, polygonum aviculare, and in thofe of ftrawberries, fragaria vefca. In thefe an elonga- ted creeping bud is protruded, and, where it touches the ground, takes root, and produces a new plant derived from its father, from which it acquires both nutriment and oxygenation ; and in ccnfcquence needs no maternal apparatus for thefe purpofes. In viviparous flowers, as thofe of allium magicum, and polygo- num viviparurnj the anthers and the ltigmas become effete and perifli *, and the lateral or paternal offspring fucceed inftead of feeds, Sect. XXXIX. 3. r. GENERATION. 385 feeds, which adhere till they are fufficiently mature, and then fall upon the ground, and take root like other bulbs. The lateral production of plants by wires, while each new plant is thus chained to \ts parent, and continues to put forth another and another, as the wire creeps onward on the ground, is exactly refembled by the tape-worm, or taenia, fo often found in the bowels, ftretching itfelf in a chain quite from the ftom- ach to the rectum. Linnaeus aflerts, r when it has been dyed on Sect. XXXIX. 3. 3. GENERATION. ' 3s7 on the head ; and in the growth of our nails from the fpecks fometimes obfervable on them ; and in the increafe of the white crefcent at the roots, and in the growth of new flefh in wounds, which confifts of new nerves as well as of new blood-veflels. 3. Laftly, Mr. Buffon has with great ingenuity imagined the exiftence of certain organic particles, which are fuppofed to be partly alive, and partly mechanic fprings. The latter of thefe were difcovered by Mr. Needham in the milt or male organ of a fpecies of cuttle fifh, called calmar ; the former, or living animal- cula, are found in both male and female fecretions, in the infufions of feeds, as of pepper, in the jelly of roafted veal, and in all other animal and vegetable fubltances. Thefe organic particles he fuppofes to exift in the fpermatic fluids of both fexes, and that they are derived thither from every part of the body, and mull therefore refemble, as he fuppofes, the parts from whence they are derived. Thefe organic particles he believes to be in con- ftant activity, till they become mixed in the womb, and then they inftantly join and produce, an embryon or fetus fimilar to the two parents. Many objections might be adduced to this ingenious theory ; I fhall only mention two. Firft, that it is analogous to no known animal laws. And fecondly, that as thefe fluids, replete with organic particles derived both from the male and female organs, are fuppofed to be fimilar ; there is no reafon why the mother mould not produce a female embryon without the af- fiftance of the male, and realize the lucina fine concubitu. See No. 8 and 9 of this fection, and Seel:. XXXVII. 3. IV. 1. I conceive the primordium, or rudiment of the em- bryon, as fecreted from the blood of the parent, to confifl of a fimple living filament as a mufcular fibre ; which I fuppofe to be an extremity of a nerve of locomotion, as a fibre of the reti- na is an extremity of a nerve of fenfation ; as for inftance one of the fibrils, which compofe the mouth of an abforbent veflel ; I fuppofe this living filament, of whatever form it may be, wheth- er fphere, cube, or cylinder, to be endued with the capability of being excited into aclion by certain kinds of ftimulus. By the ftimulus of the furrounding fluid, in which it is received from the male, it may bend into a ring : and thus form the beginning of a tube. Such moving filaments, and fuch rings, are defcribed by thofe, who have attended to microfcopic animalcula. This living ring may now embrace or abforb a nutritive particle of the fluid, in which it fwims ; and by drawing it into its pores, or joining it by compreflion to its extremities, may increafe its own length or craflitude j and by degrees the living ring may become a living tube. 2. With 388 GENERATION. Sect. XXXIX. 4. 2. With this new organization, or accretion of parts, new kinds of irritability may commence •, for fo long as there was but one living organ, it could only be fuppofed to pofTefs irrita- bility ; fince fenfibility may be conceived to be an extenfion of the effect of irritability over the reft of the fyftem. Thefe new kinds of irritability and of fenfibility in confequence of new or- ganization, appear from variety of facts in the more mature ani- mal ; thus the formation of the teftes, and confequent fecretion of the femen, occafion the paflion of lull ; the lungs muft be previously formed before their exertions to obtain frefh air can exifi ; the throat or cefophagus mud be formed previous to the fenfation or appetites of hunger and third ; one of which feems to refide at the upper end, and the other at the lower end of that canal. Thus alfo the glans penis, when it is diftended with blood, acquires a new fenfibility, and a new appetency. The fame oc- curs to the nipples of the breafts of female animals ; when they are diftended with blood, they acquire the new appetency of giving milk. So inflamed tendons and membranes, and even bones, acquire new fenfations ; and the parts of mutilated ani- mals, as of wounded mails, and polypi, and crabs, are reprodu- ced ; and at the fame time acquire fenfations adapted to their fituations. Thus when the head of a mail is reproduced after decollation with a fharp rafor, thofe curious telefcopic eyes are alfo reproduced, and acquire their fenfibility to light, as well as their adapted mufcles for retraction on the approach of injury. With every new change, therefore, of organic form, or addi- tion of organic parts, I fuppofe a new kind of irritability or of fenfibility to be produced ; fuch varieties of irritability or of fen- fibility exifl in our adult (late in the glands; every one of which is, furnifhed with an irritability, or a tafte, or appetency, and a confequent mode of action peculiar to itfelf. In this manner I conceive the veifels of the jaws to produce the teeth, thofe of the fingers to produce the nails, thofe of the ikin to produce the hair ; in the fame manner as afterwards about the age of puberty the beard and other great changes in the form of the body, and difpofition of the mind, are produced in confequence of the new fecretion of femen •, for if the animal is deprived of this fecretion thofe changes do not take place. Thefe changes I conceive to be formed not by elongation or dis- tention of primeval ftamina, but by appofition of parts ; as the mature crab-fifh, when deprived of a limb, in a certain fpace of time has power to regenerate it ; and the tadpole puts forth its feet long after its exclufion from the fpawn : and the ciferpil- m Sect. XXXIX. 4. 2. GENERATION. 389 lar in changing into a butterfly acquires a new form, with new powers, new fenfations, and new defires. The natural hiftory of butterflies, and moths, and beetles, .and gnats, is full of curiofity ; fome of them pafs many months, and others even years, in their caterpillar or grub (late ; they then reft many weeks without food, fuipended in the air, buried in the earth, or fubmerfed in water : and change themfelves during this time into an animal apparently of a different nature ; the ftomachs of fome of them, which before digefted vegetable leaves or roots, now only digeft honey ; they have •acquired wings for the purpofe* of feeking this new food, and a long pro- bofcis to collect it from flowers, and I fuppofe a fenfe of fmell to detect the fecret places. in flowers, where it is formed. The moths, which fly by night, have a much longer probofcis rolled up under their chins like a watch fpring ; which they extend to collect the honey from flowers in their fleeping (late ; when they are clofed, and the nectaries in confequence more difficult to be plundered. The beetle kind are furnifhed with an external covering of a hard material to their wings, that they may occa- fionally again make holes in the earth, in which they pafied the former ftate of their exiflence. But what moft of all diftinguifhes thefe new animals is, that they are now furnifhed with the powers of reproduction ; and that they now differ from each other in fex, which dees not ap- pear in their caterpillar or grub ftate. In fome of them the change from a caterpillar into a butterfly or moth feems to be accornpiifhed for the fole purpofe of their propagation ; fines they immediately die after this is finifhed, and take no food in the interim, as the filk-worm in this climate ; though it is poffi- ble it might take honey as food, if it was prefented to it. For in general it would feem, that food of a more ftimulating kind, the honey of vegetables inftead of their leaves, was neceflary for the purpofe of the feminal reproduction of thefe animals, exactly fimilar to what happens in vegetables \ in thefe the juices of the earth are fufBcient for their purpofe of reproduction by buds or {bulbs ; in which the new plant feems to be formed by irritative motions, like the growth of their other parts, as their leaves or roots ; but for the purpofe of feminal or amatorial reproduction, ' where fenfation is required, a more ftimulating food becomes neceflary for the anther and ftigma ; and this food is honev ; as explained in Sect. XIII. on Vegetable Animation. The gnat and the tadpole refemble each other in their change from natant animals with gills into aerial animals with lungs. ; and in their change of the element in which they live; and proba- bly of the food, with which they are fupported ; and laftly, with therr 39* GENERATION. Sect. XXXIX. 4. 3.. their acquiring in their new ftate the difference of fex, and the organs of feminal or amatorial reproduction. While the poly- pus, who is their companion in their former ftate of life, not being allowed to change his form and element, can only propa- gate like vegetable buds by the fame kind of irritative motions, which produces the growth of his own body, without the femi- nal or amatorial propagation, which requires fenfation ; and which in gnats and tadpoles feems to require a change both of food and of refpiration. From hence I conclude, that with the acqnifition of new parts, new fenfations, and new defires, as weH as new powers, are produced ; and this by accretion to the old ones, and not by dis- tention of them. And finally, that tlfe mod efTential parts of the fyftem, as the brain for the purpofe of diftributing the pow- er of life, and the placenta for the purpofe of oxygenating the blood, and the additional abforbent vefTels for the purpofe of ac- quiring aliment, are firft formed by the irritations above men- tioned, and by the pleafurable fenfations attending thofe irrita- tions, and by the exertions in confequence of painful fenfations,. fimilar to thofe of hunger and fuffocation. After thefe an ap- paratus of limbs for future ufes, or for the purpofe of moving the body in its prefent natant ftate, and of lungs for future ref- piration, and of teftes for future reproduction, are formed by the irritations and fenfations, and confequent exertions of the parts previoufly exiiiing, and to which the new parts are to be attached. 3. In confirmation of thefe ideas it may be obferved, that all the parts of the body endeavour to grow, or to make additional parts to themfelves throughout our lives ; but are reftrained by the parts immediately containing them ; thus, if the fkin be taken away, the flefhy parts beneath foon fhoot out new granulations, called by the vulgar proud flefh. If the periofteum be removed, a fimilar growth commences from the bone. Now in the cafe of the imperfect embryon, the containing or confining parts are not yet fuppofed to be formed, and hence there is nothing to re- ft rain its growth. 4. By the parts of the embryon being thus produced by nrw apportions, many phenomena both of animal and vegetable pro- ductions receive an'eafier explanation ; fuch as that many fetuf- es are deficient at the extremities, as in a finger or a toe, or in the end of the tongue, or In what is called a hare-lip with de- ficiency of the palate. For if there fliould be a deficiency in the quantity of the firft nutritive particles laid up in the egg for the reception of the firft living filament, the extreme parts, as being laft formsd, mult fiiew this deficiency by their being im- perfect. * Ti. Sect. XXXIX. 4. 5. GENERATION. 39i This idea of the growth of the embryon accords alfo with tKc production of fbme monftrous births, which confift of a duplica- tive of the limbs, as chickens with four legs ; which could not occur, if the fetus was formed by the diftention of an original ftamen, or miniature. For if there mould be a fuperfluity of the firft nutritive particles laid up in the egg for the firft living filament ; it is eafy to conceive, that a duplicature of fome parts may be formed. And that fuch fuperfluous nouriiliment fome- times exifts, is evinced by the double yolks in fome eggs, which I fuppofe were thus formed previous to their impregnation by the exuberant nutriment of the hen. This idea is confirmed by the analogy of the monfters in the vegetable world alfo 9 in which a duplicate or triplicate produc- tion of various parts of the flower is obfervable, as a triple necta- ry in fome columbines, and a triple petal in fome primrofes ; and which are fuppofed to be produced by abundant nourrfh- ment. 5. If the embryon be received into a fluid, the ftimulus of which is different in fome degree from the natural, as in the production of mule-animals, the new irritabilities or fenfibilities acquired by the increasing or growing organized parts may differ, and thence produce parts not fimilar to the father, but of a kind belonging in part to the mother ; and thus, though the original ilamen or living ens was derived totally from the father, yet new- irritabilities or fenfibilities being excited, a change of form cor- Tefponding with them wrfl be produced. Nor could the pro- duction of mules exift, if the ftamen or miniature of all the parts of the embryon is previoufly formed in the male femen, and is only diftended by nourifhment in the female uterus. Whereas this difficulty ceafes, if the embryon be fuppofed to confift of a living filament, which acquires or makes new parts with new irritabilities, as it advances its growth. The form, folidity, and colour, of the particles of nutriment , laid up for the reception of the firft living filament, as well as their peculiar kind of ftimulus, may contribute to produce a dif- ference in the form, folidity, and colour of the fetus, fo as'to re- femble the mother, as it advances in life. This alfo may es- pecially happen during the firft ftate of the exiftence of the embryon, before it has acquired organs, which can change thefe iirft nutritive particles, as explained in No. 5. 2. of this Section. And as thefe nutritive particles are fuppofed to be fimilar to thofe, which are formed for her own nutrition, it follows that the fetus fhould fo far refemble the mother. This explains, why hereditary difcafes may be derived either from the male or female parent, as well as the peculiar form of •s.ither $ 2 GENERATION. Sect. XXXIX. 4. 6, either of their bodies. Some of thefe hereditary difeafes are limply owing to a deficient activity of a part of the fyftem, as of the abforbcnc veflels, which open into the cells or cavities of the body, and thus occafion dropiies. Others are at the fame time owing to an increafe of fenfatiofl, as in fcrofula and confump-- ticn ; in thefe the obftruction of the fluids is firft caufed by the inirritability of the veiTels, and the inflammation and ulcers which fucceed, are caufed by the confequent increafe of fenfa- tion in the obfcructed part. Other hereditary difeafes, as the epilepfy, and other convulfions, confiib in too great voluntary exertions in confequence of difagreeable ienfation in fome par- ticular difeafed part. Now as the pains, which occafion thefe ' convulfions, are owing to defect of the action of the difeafed part, as fhewn in Seel:. XXXIV. it is plain, that all thefe heredi- tary difeafes may have their origin either from defective irrita- bility derived from the father, or from deficiency of the ftimu- Jns of the nutriment derived from the mother. In cither cafe the effect would be fimilar ; as a fcrofulous race is frequently produced among the poor from the deficient ftimulus of bad diet, or of hunger ; and among the rich, by a deficient irritabili- ty from their having been long accuftomed to too great ftimulus, as of vinous fpirit. 6. From this account of reproduction ic appears, that all ani- mals have a fimilar origin, viz. from a fingle living filament and that the difference of their forms and qualities has arifen only from the different irritabilities and fenfibilities^ or volunta- rities, or alTociabilities, of this original living filament ; and per- haps in fome degree from the different forms of the particles of the fluids, by which it has been at firft itimulated into activity. And that from hence, as Linnceus has conjectured in refpect to the vegetable world, it is not impoihble, but the great variety 1 fpecies of animals, which now tenant the earth, may have had their origin from the mixture of a few natural orders. And that thofe animal and vegetable mules, which could continue their fpecies, have done fo, and conltitute the numerous families of animals and vegetables which now exit! ; and that thofe mules, which were produced with imperfect organs of genera- tion, perifhed without reproduction, according to the obierva- tion of Ariftotle ; and are the animals, which we now call mult* See Botanic Garden, Part II. Note on Dianthus. Such a promifcuous intercourfe of animals is faid to exiit at this day in New South "Wales by Captain Hunter. And that not only amongft the quadrupeds and birds of different kiucb, but even amongft the fifh, and, as he believes, amongft the vegetables. He fpeaks of an animal between the opofium and th Sect. XXXIX. 4. 7. GENERATION. 3^3 ♦he kangaroo, from the ftze of a fheep to that of a rat. Many fi{h feemed to partake of the fhark ; ibme with a fkait's head and fhoulders, and the hind part of a fhark \ others with a fhark's head and the body of a mullet •, and ibme with a fhark's head and the flat body of a fling-ray. Many birds partake of the parrot ; ibme have the head, neck, and bill of a parrot, with long ilraight feet and legs ; others with legs and feet of a par- rot, with head and neck of a fea-gull. Voyage to South Wales by Captain John Hunter, p. 68. 7. All animals therefore, I contend, have a fimilar caufe of their organization, originating from a fingle living filament, en- dued indeed with different kinds of irritabilities and fenfibilities, or of animal appetencies ; which exiit in every gland, and in every moving organ of the body, and are as eiiential to living organization as chemical affinities are to certain combinations of inanimate matter. If I might be indulged to make a fimil-e in a philofophical work, I fhould fay, that the animal appetencies, are not only per- haps lefs numerous originally than the chemical affinities ; but that like thefe latter, they change with every new combination ; thus vital air and azote, when combined, produce nitrous acid % which now acquires the property of diffolving filver ; fo with every new additional part to the embryon, as of the throat or lungs, I fuppofe a new animal appetency to be produced. In this early formation of the embryon from the irritabilities, fenfibilities, and affociabilities, and eonfequent appetencies, the faculty of volition can fcarcely be fuppoled to have had its birth. For about what can the fetus deliberate when it has no choice of objects ? But in the more advanced (late of the fetus, it evident- ly pofferTes volition ; as it frequently changes its attitude, though it feems to lleep the greateft part of its time ; and afterwards the power of Volition contributes to change or alter many parts of the body during its growth to manhood, by our early modes of exertion in the various departments of 1-ife. All thefe facul- ties then conftitute the vis fabricatrix, and the vis confervatrix, as well as the vis medicatrix of nature, fo much fpoken of, but. fo little under flood by philofophers. 8. "When we revolve in our minds, firft, the great changes, which we fee naturally produced in animals after then nativity, as in the production of the butterfly with painted wings from the crawling caterpillar ; or of the refpiring Irog from the fub- natant tadpole ; from the feminine boy to the bearded man, and from the infant girl to the tadrefcent woman •, both which changes may be prevented by certain mutilations of the glands neceilary to reproduction. Vol, I. C c c Speondly, 394 GENERATION. Sect. XXXIX. 4. ST. Secondly, when we think over the great changes introduced in- tovarious animals by artificial or accidental cultivation, as inhorics, which we have exercifed for the different purpofes of llrength or fwiftnefs, in carrying burthens or in running races ; or in dogs, which have been cultivated for ftrength and courage, as the bull- dog ; or for acutenefs of his fenfe of fmell, as the hound and fpaniel -, or for the fwiftnefs of his foot, as the greyhound ; or for his fwimming in the water, or for drawing fnow-iledges, as the rough-haired dogs of the north ; or lailly, as a play-dog for children, as the lap-dog -7 with the changes of the forms of the cattle, which have been domefticated from the greateft antiquity, r.; camels, and fheep •, which have undergone fo total a transfor- mation, that we are now ignorant from what fpecies of wild ani- ls they had their origin. Add to thefe the great changes of fhape and colour, which we daily fee produced in fmaller ani- mals from our domeftication of them, as rabbits, or pigeons ; or from the difference of climates and even of feafons ; thus the fheep of warm climates are covered with hair inftead of wool j- and the hares and partridges of the latitudes, which are long buri- ed in fnow, become white during the winter months ; add to- thefe the various changes produced in the ferrns of mankind, by their early modes of exertion ; or by the difeafes occafioned by their habits of life j both of which became hereditary, and that t] rough many generations. Thofe who labour at the anvil, the oar, or the loom, as well as thofe who carry fedan-ch airs, or who have been educated to dance upon the rope, are diftinguifliable by the fhape cf their limbs ; and the difeafes occanoned by in- toxication deform the countenance with leprous eruptions, or the body with tumid vifcera, or the ioints with knots and diflortions. Thirdly,, when we enumerate the great changes produced in the fpecies of animals before their nativity \ thefe are fuch as referable the form or colour of their parents, which have be altered bv the cultivation or accidents above related, and are thur, continued to their poftevity. Or they are changes produ- ced by the mixture of fpecies as in mules ; or changes produced probably by the exuberance of nouriihment fuppued to the i tils, a^ in monltrous births with additional limbs *, many of thefe enormities of fhape are propagated, and continued as a variety at leaf!, if not as a new fpecies of animal. I have (etn a breed of cat; with an additional claw on every foot; of poultry all with an additional claw, and with wings to their feet ; and of others without rumps. Mr. BurTon mentions a breed of dog without tails, which are common at Rome arid at Naples, which he fuppojTes to have been produce^ by a cuftom long eftablifhi of culling their tails- clofe off. There are many kinds of t is« admixed Sect. XXXTX. 4. 8. GENERATION. 35? admired for their peculiarities, which are monfters thus produ- ced and propagated. And to thefe muft he added, the changes produced by the Imagination of the male parent, as will be treat- ed of more at large in No. VI. of this Section. When we coniider all thefe changes of animal form, and in- numerable others, which may be collected from the books of nat- ural hiftory } we cannot but be convinced, that the fetus or em- iryon is formed by appofition of new part.>, and not by the dis- tention of a primordial neft of germes, included one within an- .other, like the cups of 2 conjurer. .Fourthly, when we revolve in our minds the great fimilarity of ftrufture which obtains in all the warm blooded animals, as well quadrupeds, birds, and amphibious animals, as in mankind 3 from the moufe and bat to the elephant and whale ; one is led to conclude, that they have alike been produced from a fimilar living filament. In fome this filament in its advance to maturi- ty has acquired hands and fingers, with a fine fenfe of -touch, as in mankind. In others it has acquired claws or talons, as io tygers and eagles. In otherss toes with an intervening web, or membrane, as in feals and geefe. In others it has acquired clo- ven hoots, as in cows and fwine ; and whole hoofs in others, as. in the horfe. While in the bird Jund this original living fila- ment has put forth wings inftead of arms or legs, and feathers inftead of hair. In fome it has protruded horns on the fore- head initead of teeth in the fore part of the upper jaw ; in others tuihes inftead ofiiorns ; and in others beaks inftead of .either. And all this exactly as is daily feen in the tranfmuta- tions of the tadpole, which acquires legs and lungs, when he wants them ; and lofes his tail, when it is no longer of fervice to him. Fifthly, from their firfi rudiment, or primordium, to the ter- mination of their lives, ail animals undergo perpetual transform- ations ; which are in part produced by their own exertions in confequence of their defires and averfions, of their pleafures and their pains, or of irritations, or of afibciations ; and many of thefe acquired forms or propenfities are tranfmitted to their pofterity. See Sect. XXXI. 1. As air and water are fupplied to animals in fumcient profu- lion, the three great objects of defire, which have changed the forms of many animals by their exertions to gratify them, are thofe of lull, hunger, and fecurity. A great want of one part of the animal world has confifted in the defire of the exclufive pofleflion of the females ; and thefe have acquired weapons to combat each other for this purpofe, as the very thick, fhield-like, horny Ikin on the moulder of the boar is a defence only againft animal^ 396 GENERATION. Sect. XXXIX. 4. 8, animals of his own fpecies, who ftrike obliquely upwards, nor are his tufhes for other purpofes, except to defend himfelf, as he is not naturally a carnivorous animal. So the horns of the ft are (harp to offend his adversary, but are branched for the pur- pofe of parrying or receiving the thru ft s of horns fimilar to his own, and have therefore been formed for the purpofe of com- bating other flags for the exclufive poffefiion of the females ; who are obferved, like the ladies in the times of chivalry, to at- tend the car of the victor. The birds, which do not carry food to their young, and do not therefore marry, are armed with fpurs for the purpofe of fighting for the exclufive poffellion of the females, as cocks and quails. It is certain that thefe weapons are not provided for their defence againft other adverfaries, becaufe the females of thefe fpecies are without this armour. The final caufe of this conteft amongft the males feems to be, that the ftrongef}: and mod active animal fhould propagate the fpecies, which fhouki thence become improved. Another great want confifts in the means of procuring foci, which has diverlified the forms of all fpecies of animals. Thus the nofe of the fwine has become hard for the purpofe of turn- ing up the foil in fearch of infects and of roots. The trunk of the elephant is an elongation of the nofe for the purpofe of pull- ing down the branches of trees for his food, and for taking up water without bending his knees. Beads of prey have acquired ftrong jaws or talons. Cattle have acquired a rough tongue and a rough palate to pull off the blades of grafs, as cows and iheep. Some birds have acquired harder beaks to crack nuts, as the parrot. Others have acquired beaks adapted to break the harder feeds, as fparrows. Others for the fofter feeds of flowers, or the buds of trees, as the finches. Other birds have acquired long beaks to penetrate the moifter foils in fearch of infects or roots, as woodcocks ; and others broad ones to filtrate the water of lakes, and to retain aquatic infects, as ducks. All which feem to have been gradually produced during many generations by the perpetual endeavour of the creatures to fupply the want of food, and to have been delivered to their poflerity with conftant improvement of them for the purpofes required. The third great want amongft animals is that of fecurity, which feems much to have diverlified the forms of their bodies and the colour of them ; thefe coniift in the means of efcaping other animals more powerful than themfelves. Hence fome animals have acquired wings inftead of legs, as the fmaller birds, for the purpofe of efcape. Others great length of fin, or of mem- brane, as the flying ftth, and the bat. Others great fwiftnefs of Sect. XXXIX. 4. 8. GENERATION. 397 of foot, as the hare. Others have acquired hard or armed fhells* as the tortoiie and the echinus marinus. Mr. Ofbeck, a pupil of Linnaeus, mentions the American frog-fifh, lophius hiftrio, which inhabits the large floating iflands of fea-weed about the Cape of Good Hope, and has iulcra re- icmbling leaves, that the fifhes of prey may miftake it for the fea-weed, which it inhabits. Voyage to China, p. 113. The contrivances for the purpofes of fecurity extend even to vegetables, as is feen in the wonderful and various means of their concealing or defending their honey from infects, and their feeds from birds. On the other hand fwiftnefs of wing has been acquired by hawks and fwailows to purfue their prey ; and a probofcis of admirable ftructure has been acquired by the bee, the moth, and the humming bird, for the purpofe of plundering the nectaries of flowers. All which feem to have been formed by the original living filament, excited into action by the hecef- fities of the creatures, which pofTefs them, and on which their exiftence depends. From thus meditating on the great fimilarity of the ftructure of the warm-blooded animals, and at the fame time of the great changes they undergo both before and after their nativity ; and by considering in how minute a portion of time many of the changes of animals above defcribed have been produced ; would it be too bold to imagine, that in the great length of time, fince the earth began to exift, perhaps millions of ages before the commencement of the. hiftorv of mankind, would it be loo bold to imagine, that all warm-blooded animals have arifen from one living filament, which the great First Cause endued with an- imality,with the power of acquiring new parts attended with new propenfities, directed by irritations, fenfations, volitions, and aflb- ciations ; and thus pofiefTing the faculty of continuing to improve by its own inherent activity, and of delivering down thofe im- provements by generation to its poflerity, world without end ? Sixthly, The cold-blooded animals, as the fifh-tribes, which are furnifhed with but one ventricle of the heart, and with gills inftead of lungs, and with fins inftead of feet or wings, bear a great fimilarity to each other ; but they differ, neverthelefs, fo much in their general ftructure from the warm-blooded animals, that it may not feem probable at firft view, that the fame living filament could have given origin to this kingdom of animals, as to the former. Yet are there fome creatures, which unite or partake of both thefe orders of animation, as the whales and icals ; and more particularly the frog, who changes from an aquatic animal furnifhed with gills to an aerial one furnifhed I with lungs. The 1&6 GENERATION. Sect. XXXIX. 4. 8. The numerous tribes of infects without wings, from the fpi- der to the fcorpion, from the Sea to the lobfter ; or with wine*. from the gnat and the ant to the wafp and the dragon-fly, dif- fer fo totally from -each other, and from the red-blooded claffes above defcribed, both in the forms of their bodies, and their modes of life ; befides the organ of fenfe, which they feem to pofTels in their antennae or horns, to which it has been thought by iome naturalifts, that other creatures have nothing fimilar ; that it can fcarcely be fuppofed that this nation of animals could have been produced by the fame kind of living filament, as the red-blooded claffes above mentioned. And yet the changes -which many of them undergo in their early iiate to that of their maturity, are as different, as one animal can be from another. As thole of the gnat, which pafTes his early Hate in water, and then ftretching out his new wings, and expanding his new lungs, rifes in the air -, as of the caterpillar, and bee-nymph, which feed on vegetable leaves or farina, and at length burfhng from their felf-foi rned graves, become beautiful winged inhab- itants of dit flciesj journeying from flower to flower, and^nourifh- ed by the ambrofial food of honey. There is Mill another clafs of animals, which are termed ver- mes by Linnseus, which are without feet, or brain, and are her- maphrodites, as worms, leeches, fnaiis, (heil-fiih, coralline infects, and fponges ; which pofTefs the fimpieit ftructure of all animals, and appear totally different from thoie already defcribed. The /implicify of their ftructure, however, can afford no argument againft their having been produced from a living filament as above contended. Lafl: of all the various tribes of vegetables are to be enumera- ted amongft the inferior orders of animals. Of thefe the an- thers and itigmas have already been (hewn to pofTefs fome organs of fenfe, to be nouriihed by honey, and to have the power of generation like infects, and have thence been announced amongfl the animal kingdom in Sect. XIII. and to thefe muft be added the buds and bulbs which conftitute the viviparous offspring of vegetation. The former I fuppofe to be beholden to a fingle living filament for their feminal or amatorial procreation j and the latter to the fame caufe for their lateral or branching gener- ation, which they poflefs in common with the polypus, taenia, and volvox -, and the fimplicity of which is an argument in fa- vour of the fimilarity of its caufe. Linmeus fuppofes, in the Introduction to his Natural Orders, that very few vegetables were at firft created, and that their numbers were increafed by their intermarriages, and adds, fua- denffaec Creatoris leges a fimplicibus ad compofita. Many other Sect. XXXIX. 4. £ GENERATION. 309 other changes feem to have arifen in them by their perpetual - eonteft for light and air above ground, and for food or moifture beneath the foil. As noted in Botanic Garden, Part II. Note on Cufcuta. Other changes of vegetables from climate, or other caufes, are remarked in the Note on Curcuma in the fame work. From thefe one might be led to imagine, thai each plant at firft confided of a (ingle bulb or flower to each root, as the gentianella and claify ; and that in the conteft for air and light new buds grew on the old decaying flower item, mooting down their elongated roots to the ground, and that in procefs of ages tall trees were thus formed, and an individual bulb became a fwarra of vegetables. Other plants, which in this conteft for light and air were too (lender to rife by their own (crength, learned by degrees to adhere to their neighbours, either bv put- ting forth roots like the ivy, or by tendrils like the vine, or by fpiral contortions like the honey-fuckle *, or by growing upon them like the mifleto, and taking nourimment from their barks ; or by only lodging or adhering on them, and deriving nouriih- rnent from the air, as tillandfia. Shall we then fay that the vegetable living filament was orig- inally different from that of each tribe of animals above defcri- bed ? And that the productive living filament of each of thofe tribes was different originally from the other ? Or, as the earth and ocean were probably peopled with vegetable productions long before the exiftence of animals ; and many families of thefe animals long before other families of them, (hall we conjecture that one and the fame kind of living filaments is and has been the caufe of all organic life ? If this gradual production of the fpecies and genera of animals be affented to, a contrary circumitance may be fuppofed to have occurred, namely, that fome kinds by the great changes of the elements may have been deftroyed. This idea is (hewn to our fenfes by contemplating the petrifactions of *4hells, and of vegetables, which may be laid, like buds and medals, to record the hiitory of remote times. Of the myriads of belemnites, cop- nua ammonis, and numerous other petrified (hells, which are found in the mafies of lime-flone, which have been produced by them, none now are ever found in our feas, or in the leas of other parts of the world, according to the obiervations of many naturalifts. Some of whom have imagined, that moft of the inhabitants of the fea and earth of very remote times are now extinct ; as they fcarcely admit, that a fingle foifil (hell bears a (trict fimilitude to any recent ones, and that the vegetable im- preflions or petrifactions found in iron-ores, clay, or fandftone, of which there are many of the fern kind, are not fimilar to any plants 40© GENERATION. Sect. XXXIX. 4. g. plants of this country, nor accurately correfpond with thcfe of other climates, which is an argument countenancing the chang- es in the forms, botli of animals and vegetables, during the pro- greiTive lhufture of the globe, which we inhabit. See Town- fon's Philof. of Mineralogy, p. 1 10. This idea of the gradual formation and improvement of the animal world accords with the obfervations of lome modern phi- loibphers, who have fuppofed that the continent of America has been raifed out of the ocean at a later period of time than the other three quarters of the globe, which they deduce from the greater comparative heights of its mountains, and the confe- rment greater coldnefs of its refpeclive climates, and from the lefs fize and ilrength of its animals, as the tygers and allegators compared with thofe of Afia or Africa. And laftly, from the lefs progrefs in the improvements of the mind of its inhabitants in refpeCt. to voluntary exertions. This idea of the gradual formation and improvement of the animal world feems not to have been unknown to the ancient philofophers. Plato having probably obferved the reciprocal generation of inferior animals, as fnails and worms, was of opin- ion, that mankind with all other animals were originally herma-< phrodites during the infancy of the world, and were in procefs of time feparated into male and female. The breads and teats of all male quadrupeds, to which no ufe can be now af- figned, adds perhaps fome fhadow of probability to this opinion. Linnseus excepts the horfe from the male quadrupeds, who have teats -, which might have fhewn the earlier origin of his exig- ence ; but Mr. J. Hunter afferts, that he has difcovered the vef- tiges of them on his iheath, and has at the fame time enriched natural hiftory with a very curious fa£t concerning the mile pigeon ; at the time of hatching the eggs both the male and fe~ male pigeon undergo a great change in their crops -, which thick- en and become, corrugated, and fecrete a kind of milky fluid, which coagulates, and with which alone they for a few days feed their young, and afterwards feed them with this coagulated fluid mixed with other food. How this refembles the breafts of female quadrupeds after the production of their young ! and how extraordinary, that the male mould at this time give milk as well as the female ! See Botanic Garden, Part II. Note on Curcuma. The late Mr. David Hume, in his pofthumous works, places the powers of generation much above thofe of our boafled rea- fon ; and adds, that reafon can only make a machine, as a clock or a ihip, but the power of generation makes the maker of the machine j and probably from having obferved, that the greateft . . part Sect. XXXIX. 5. 1. GENERATION. 401 part of the earth has been formed out of organic recrements ; as the immenfe beds of limeftone, chalk, marble, from the (hells of fi(h ; and the extenfive provinces of clay, fandftone, ironftone, coals, from decompofed vegetables •, all which have been firft produced by generation, or by the fecretions of organic life ; he concludes that the world itfelf might have been generated, rath- er than created ; that is, it might have been gradually produced from very fmall beginnings, increafing by the activity of its in- herent principles, rather than by a fudden evolution of the whole by the Almighty fiat. — What a magnificent idea of the infinite power of the Great Architect ! The Cause of Causes ! Parent of Parents ! Ens Entium ! For if we may compare infinities, it would feem to require a greater infinity of power to caufe the caufes of effects, than to caufe the effects themfelves. This idea is analogous to the im- proving excellence obfervable in every part of the creation ; iuch as in the progreflive increafe of the folid or habitable parts of the earth from water ; and in the progreflive increafe of the wifdom and happinefs of its inhabitants ; and is confonant to the idea of our prefent fituation being a ftate of probation, which by our exertions we may improve, and are confequently refpon- fible for our actions. V. 1 . The efficient caufe of the various colours of the eggs of birds, and of the hair and feathers of animals, is a fubject fo curious, that I (hall beg to introduce it in this place. The colours of many animals feem adapted to their purpofes of con- cealing themfelves either to avoid danger, or to fpring upon their prey. Thus the fnake, and wild cat, and leopard, are fo colour- ed as to refemble dark leaves and their lighter interftices ; birds refemble the colour of the brown ground, or the green hedges, which they frequent j and moths and butterflies are coloured like the flowers which they rob of their honey. Many inftances are mentioned of this kind in Botanic Garden, Part II. Note on Rubia. Thefe colours have, however, in fome inftances another ul'e, as the black diverging area from the eyes of the fwan ; which, as his eyes are placed lefs prominent than thofe of other birds, for the convenience of putting down his head under water, pre- vents the rays of light from being reflected into his eyes, and thus dazzling his fight, both in air and beneath the water ; which muft have happened, if that furface had been white like the » of his feathers. There is a ftill more wonderful thing concerning thefe colours adapted to the purpofe of concealment ; which is, that the ej of birds are fo coloured as to refemble the colour of the adja* Vol, I. D d d obj 4©2 GENERATION. Sect. XXXIX. 5. 1. objects and their interftices. The eggs of hedgebirds are green- ifh with dark fpots *, thofe of crows and magpies, which are feen from beneath through wicker nefts, are white with dark fpots ; and thofe of larks and partridges are ruflet or brown, like their nefts or fituations. A thing Hill more afbonifhing is, that many animals in coun- tries covered with fnow become white in winter, and are faid to change their colour again in the warmer months, as bears, hares, and partridges. Our domefticated animals lofe their natural colours, and break into great variety, as horfes, dogs, pigeons. The final caufe of thefe colours is eafily underftood, as they ferve fome purpofes of the animal, but the efficient caufe would feem almoft beyond conjecture. Firit, the choroid coat of the eye, on which the femitranfpa- rent retina is expanded, is of different colour in differnt ani- mals ; in thofe which feed on grafs it is green ; from hence there would appear fome connexion between the colour of the choroid coat and of that conftantly painted on the retina by the green grafs. Now, when the ground becomes covered with fnow, it would feem, that that action of the retina, which is called whitenefs, being conftantly excited in the eye, may be* gradually imitated by the extremities of the nerves of touch, or rete mucofum of the fkin. And if it be fuppofed, that the ac- tion of the retina in producing the perception of any colour confilts in fo difpofmg its own fibres or furface, as to reflect thofe coloured rays only, and tranfmit the others like foap-bub- bles ; then that part of the retina, which gives us the perception of fnow, mull at that time be white j and that which gives us the perception of grafs, muft be green. Then if by the laws of imitation, as explained in Section XII. 33. and XXXIX. 6. the extremities of the nerves of touch in the rete mucofum be induced into iimilar action, the fkin or feathers, or hair, may in like manner fo difpofe their extreme fibres, as to reflect white ; for it is evident, that all thefe parts were originally obedient to irritative motions during their growth, and probably continue to be fo *, that thofe irritative motions are not liable in a healthy itate to be fucceeded by fen- iaticn ; which however is no uncommon thing in their difeafed (late, or in their infant ftate, as in plica polonica, and in very young pen-feathers, which are (till full of blood. It was (hewn in Section XV. on the Production of Ideas, that the moving organ of fenfein fome eircumllance* rcfembled the object which produced that motion. Hence it may be conceiv- ed, that the rete mucofum, which is the cxtrcmitv of the nerves I touch, may by imitating the motions of the retina become coloured. Sect. XXXIX. 5. 2. GENERATION. 403 coloured. And thus, like the fable of the chameleon, all ani- mals may poffefs a tendency to be coloured fomewhat like the colours they molt frequently infpect, and finally, that colours may be thus given to the egg-lhell by the imagination of the fe- male parent ; which fhell is previoufly a mucous membrane* in- dued with irritability, without which it could not circulate its fluids, and increafe in its bulk. Nor is this more wonderful than that a fingle idea of imagination fhould in an inftant colour the whole furface of the body of a bright fcarlet, as in the blufli of fhame, though by a very different procefs. In this intricate fub- ject nothing but loofe analogical conjectures can be had, which may however lead to future difcoveries ; but certain it is that both the change of the colour of animals to white in the winters of fnowy countries, and the fpofs on birds' eggs, mud have fome efficient caufe ; fince the uniformity of their production (hews it cannot arife from a fortuitous concurrence of circumftances ; and how is this efficient caufe to be detected, or explained, but from its analogy to other animal facts ? 2. The nutriment fupplied by the female parent in vivipa- rous animals to their young progeny may be divided into three kinds, correfponding with the age of the new creature. 1. The nutriment contained in the ovum as previoufly prepared for the embryon in the ovary. 2. The liquor amnii prepared 'for the fetus in the uterus, and in which it fvvims ; and laftly, the milk prepared in the pectoral glands for the new-born child. There is reafon to conclude that variety of changes may be produced in the new animal from all thefe fources of nutriment, but par- ticularly from the firft of them. The organs of digeftion and of fanguiflcation in adults, and afterwards thofe of fecretion, prepare or feparate the particles proper for nourifhment from other combinations of matter, or recombine them into new kinds of matter, proper to excite into action the filaments, which abforb or atj|act them by animal ap- petency. In this procefs we muft atteim not only to the action ot the living filament which receives a nutritive particle to its bofom, but alio to the kind of particle, in refpect to form, or Cze, or colour, or hardnefs, which is thus previoufly prepared for it by digeftion, fanguiflcation, and fecretion. Now as the firft filament of entity cannot be furnilhed with the preparative or- gans above mentioned, the nutritive particles, which are at firft to be received by it, are prepared by the mother j and depofited in the ovum ready for its reception. Thefe nutritive particles muft be fuppoied to differ in fome refpects, when thus prepared by different animals. They may differ in fize, folidity, colour, and form j and yet may be fufficiently congenial to the living filament! 4 GENERATION. Sect. XXXIX. 5. 2. filament, to which they are applied, as to excite its activity by their flimulus, and its animal appetency to receive them, and to combine them with itfelf into organization. By this firft nutriment thus prepared for the embryon is not meant the liquor amnii, which is produced afterwards, nor the larger exterior parts of the white of the egg •, but the fluid pre- pared, I fuppofe, in the ovary of viviparous animals, and thai which immediately furrounds the cicatricula of an impregnated egg, and is vifible to the eye in a boiled one. Now thefe ultimate particles of animal matter prepared by the glands of the mother may be fuppofed to refemble the fimilar ultimate particles, which were prepared for her own nourifh- ment ; that is, to the ultimate particles of which her own or- ganization confifts. And that hence when thefe become com- bined with a new embryon, which in its early date is not fur- nifhed with ftomach, or glands, to alter them ; that new embry- on will bear fome refemblance to the mother. This feems to be the origin of the compound forms of mules, which evidently partake of both parents, but principally of the male parent. In this production of chimeras the ancients feem to have indulged their fancies, whence the fphinxes, griffins, dragons, centaurs, and minotaurs, which are vanifhed from mod- ern credulity. It would feem, that in thefe unnatural conjunctions, when the nutriment depofited by the female was fo ill adapted to flimu- late the living filament derived from the male into action, and to be received, or embraced by it, and combined with it into organization, as not to produce the organs neceffary to life, as the brain, or heart, or ftomach, that no mule was produced. Where all the parts neceffary to life in thefe compound animals were formed fufhciently perfect, except the parts of generation, thofe animals were produced which are now called mules. The formation of the organs of fexual generation, in contra- diftinction to that by lateral buds, in vegetables, and in fome animals, as the polypus, the taenia, and the volvox, feems the chef d'eeuvre, the mafter-piece of nature ; as appears from ma- ny flying infects, as in moths and butterflies, who feem to un- dergo a general change of their forms folely for the purpofe of fexual reproduction, and in all other animals this organ is not complete till the maturity of the creature. Whence it happens that, in the copulation of animals of different fpecies, the parts neceffary to life are frequently completely formed ; but thofe for the purpofe of generation are defective, as requiring a nicer organization ; or more exact coincidence of the particles of nu- triment to the irritabilities or appetencies of the original living filament. Sect. XXXIX. 5. 2. GENERATION. 405 filament. Whereas thofe mules, where all the parts could be perfectly formed, may have been produced in early periods of time, and may have added to the numbers of our various fpecies of animals, as before obferved. As this production of mules is a conftant effect from the con- junction of different fpecies of animals, thofe between the horfe and the female afs always refembling the horfe more than the afs i and thofe on the contrary, between the male afs and the mare, always reiembling the afs more than the mare ; it cannot be afcribed to the imagination of the male animal which cannot be fuppofed to operate fo uniformly ; but to the form of the firft nutritive particles, and to their peculiar ftimulus exciting the living filament to felect and combine them with itfelf. There is a fimilar uniformity of effect, in refpect to the colour of the progeny produced between a white man, and a black woman, which, if I am well informed, is always of the mulatto kind, or a mixture of the two *, which may perhaps be imputed to the peculiar form of the particles of nutriment fupplied to the embryon by the mother at the early period of its exiftence, and their peculiar ftimulus •, as this effect, like that of the mule progeny above treated of, is uniform and confident, and cannot therefore be afcribed to the imagination of either of the parents. Dr. Thunberg obferves, in his Journey to the Cape of Good Hope, that there are fome families, which have defcended from blacks in the female line for three generations. The firft genera- tion proceeding from an European, who married a tawny Have, remains tawny, but approaches to a white complexion ; but the children of the third generation, mixed with Europeans, become quite white, and are often remarkably beautiful. Vol. i. p. 112. When the embryon lias produced a placenta, and furnifhed itfelf with veffels for felection of nutritious particles, and for oxygenation of them, no great change in its form or colour is likely to be produced by the particles of fuftenance it now take3 from the fluid, in which it is immerfed ; becaufe it has now ac- quired organs to alter or new combine them. Hence it con- tinues to grow whether this fluid, in which it fwims, be formed by the uterus or by any other cavity of the body, as in extra- uterine geftation \ and which would feem to be produced bv the ftimulus of the fetus on the fides of the cavity, where it is found, as mentioned before. And thirdly, there is ftill lefs rea- fon to expect any unnatural change to happen to the child after its birth from the difference of the milk it now takes ; becaufe it has acquired a ftomach, and lungs, and glands, of iuilicient power to decompofe and recombine the milk ; and thus to pre- pare from it the various kinds of nutritious particles, which the appetencies of the various fibrils or nerves may require. From 4o6 GENERATION. Sect. XXXIX. 6. i. From all this reafoning I would conclude, that though the imagination of the female may be fuppofed to affeel: the embry- on by producing a difference in its early nutriment 5 yet that no fuch power can affeel: it after it has obtained a placenta, and other organs ; which may felect or change the food, which is prefented to it either in the liquor amnii, or in the milk. Now as the eggs in pullets, like the feeds in vegetables, are produced gradually, long before they are impregnated, it does not appear how any fudden effect of imagination of the mother at the time of impregnation can produce any confiderable change in the nu- triment already thus laid up for the expected or defired embryon. And that hence any changes of the embryon, except thofe uni- form ones in the production of mules and mulattoes, more probably depend on the imagination of the male parent. At the fame time it feems manifeil, that thofe monitrous births, which confift in fome deficiencies only, or fome redundancies of parts, originate from the deficiency or redundance of the firft nutriment prepared in the ovary, or in the part of the egg im- mediately furrounding the cicatricula, as defcribed above j and which continues fome time to excite the firft living filament into action, after the finiple animal is completed ; or ccafes to excite it, before the complete form is accomplished. The for- mer of thefe circumftances is evinced by the eggs with double yolks, which frequently happen to our domefticated poultry, and which, I believe, are fo formed before impregnation, but which would be well worth attending to, both before and after im- pregnation ; as it is probable, fomething valuable on this fubjecl: might be learnt from them. The latter circumftance, or that of deficiency of original nutriment, may be deduced from re- verfe analogy. There are, however, other kinds of monftrous births, which neither depend on deficiency of parts, or fupernumerary ones ; nor are owing to the conjunction of animals of different fpecies ; but which appear to be new conformations, or new difpofitions of parts in refpect to each other, and which, like the variation of colours and forms of our domefticated animals, and probably the fexual parts of all animals, may depend on the imagination of the male parent, which we now come to confider. VI. 1. The nice actions of the extremities of our various glands are exhibited in their various productions, which are be- lieved to be made by the gland, and not previoufly to exift as fuch in the blood. Thus the glands, which conftitute the liver, make bile ; thofe of the ftomach make gaftric acid ; thofe be- neath the jaw, faliva ; thofe of the ears, ear-wax j and the like. Every kind of gland muff poffefs a peculiar irritability, and probably Sect. XXXIX. 6. i. GENERATION. 407 probably a fenfibility, at the early ftate of its exiftence ; and muft be furnifhed with a nerve of fenfe, or of motion, to per- ceive, and to feledt, and to combine the particles, which com- pofe the fluid it fecretes. And this nerve of fenfe which per- ceives the different articles which cornpofe the blood, muff at leaf! be conceived to be as fine and fubtile an organ, as the op- tic or auditory nerve, which perceives light or found. See Sea. XIV. 9. But in nothing is this nice action of the extremities of the blood-veffels fo wonderful, as in the production of contagious matter. A fmall drop of variolous contagion diffufed in the blood, or perhaps only by being inferted beneath the cuticle, after a time, (as about a quarter of a lunation,) excites the ex- treme vefTels of the fkin into certain motions, which produce a iimilar contagious material, filling with it a thoufand puftules. So that by irritation, or by fenfation in confequence of irrita- tion, or by aflbciation of motions, a material is formed by the extremities of certain cutaneous veiTels, exactly fimilar to the ftimulating material, which caufed the irritation, or confequent fenfation, or aflbciation. Many glands of the body have their motions, and in confe- quence their fecreted fluids, affected by pleafurable or painful ideas, fince they are in many inftances influenced by feniltive aflb- ciations, as well as by the irritations of the particles of the palling blood. Thus the idea of meat, excited in the minds of hungry dogs, by their fenfe of vilion, or of fmell, increafes the difcharge of faliva, both in quantity and vifcidity •, as is feen in its hanging down in threads from their mouths, as they (land round a din- ner-table. The fenfations of pleafure, or of pain, of peculiar kinds, excite in the fame manner a great difcharge of tears ; which appear alfo to be more faline at the time of their fecretion, from their inflaming the eyes and eye-lids. The palenefs from fear, and the blufh of fhame, and of joy, are other inftances of the effects of painful or pleafurable fenfations, on the extremi- ties of the arterial fyftem. It is probable, that the pleafurable fenfation excited in the ftomach by food, as well as its irritation, contributes to excite into action the gaftric glands, and to produce a greater fecre- tion of their fluids. The fame probably occurs in the fecretion of bile; that is, that the pleafurable fenfation excited in the ftomach, affects this fecretion by feniitive aflbciation, as well as by irritative aflbciation. And laflly it would feem, that all the glands in the body have their fecreted fluids affected, in quantity and quality, by the pleafurable or painful fenfations, which produce or accom- pany 4©8 GENERATION. Sect. XXXIX. o. 2. pany thofe fecretions. And that the pleafurable fenfations ariiing from thefe fecretions may constitute the unnamed pleas- ure of cxiftence, which is contrary to what is meant by tsedium vita:, or ennui ; and by which we fometimes feel ourfelves hap- py, without being able to afcribe it to any mental caufe, as af- ter an agreeable meal, or in the beginning of intoxication. Now it would appear that no fecretion or excretion of fluid is attended with fo much agreeable fenfation, as that of the femen ; and it would thence follow, that the glands which per- form this fecretion, are more likely to be much affected by their catenations with pleafurable fenfations. This circumftance is certain, that much more of this fluid is produced in a given time, when the object of its exclufjon is agreeable to the mind. 2. A forcible argument, which (hews the neceffity of pleafura- ble fenfation to copulation, is, that the act cannot be performed without it •, it is eaiily interrupted by the pain of fear or bafh- fulnefs i and no efforts of volition or of irritation can effect this procefs, except Inch as induce pleafurable ideas or fenfa- tions. See Sect. XXXIII. i. i. A curious analogical circumftance attending hermaphrodite infects, as fnails and worms, (till further illultrates this theory ; if the fnail or worm could have impregnated itfelf, there might have been a faving of a large male apparatus ; but as this is not fo ordered by nature, but each fnail and worm reciprocally receives and gives impregnation, it appears, that a pleafurable excitation feems alfo to have been required. This wonderful circumftance of many infects being her- maphrodites, and at the fame time not having power to itru pregnate themfelves, is attended to by Dr. Lifter, in his Exer- Gitationes Anatom. de Limncibus, p. 145 ; who, amongft many other final cauies, which he adduces to account for it, adds, ut tarn triitibus et frigidis animalibus majori cum voluptate perii- ciarur venus. There is, however, another final caufe, to which this circum- ftance may be imputed : it was obferved above, that vegetable buds and bulbs, which are produced without a mother, are al- ways exact refemblances of their parent ; as appears in grafting fruit trees, and in the flower-buds of the dioiceous plants, which are always of the fame fex on the fame tree ; hence thofe hermaphrodite infects, if they could have produced young without a mother, would not have been capable of that change or improvement, which is feen in all other animals, and in thofe vegetables, which are procreated by the male embryon received and nouriflied by the female. And it is hence probable, that if vegetables could only have been produced by buds and bulbs, and Sect. XXXIX. 6. 3. GENERATION, and not by fexual generation, that there would not at this time have exifled one thousandth part of their p'refent number of fpe- cies *, which have probably been originally mule-productions ; nor could any kind of improvement or change have happened to them, except by the difference of foil or climate. 3. I conclude that the imagination of the male at the time of copulation, or at the time of the fecretion of the femen, may fo affect this fecretion by irritative or fenfitive aflbciation, as defcribed in No. V. 1. of this fection, as to canfe the produc- tion of fimilarity of form and of features, with the diftinction of fex; as the motions of the chiffel of the turner imitate or correfpond with thofe of the ideas of the artift. It is not here to be underftood, that the firft living fibre, which is to form an animal, is produced with any fimilarity of form to the future an- imal ; but with propenfities, or appetences, which fhall produce by accretion of parts the fimilarity of form, feature, or fex, cor- refponding to the imagination of the father. Our ideas are movements of the nerves of fenfe, as of the optic nerve in recollecting vifible ideas, fuppofe of a triangular piece of ivory. The fine moving fibres of the retina act in a manner to which I give the name of white ; and this action is confined to a defined part of it ; to which figure I give tli£ name of triangle. And it is a preceding pleafurable fenfa- tion exifling in my mind, which occafions me to pro- duce this particular motion of the retina, when no triangle is prefent. Now it is probable, that the acting fibres of the ulti- mate terminations of the fecreting apertures of the vefTels of the teftes, are as fine as thofe of the retina ; and that they are liable to be thrown into that peculiar action, which marks the fex of the fecreted embryon, by fympathy with the pleafurable motions of the nerves of vifion or of touch ; that is, with certain ideas of imagination. From hence it would appear, that the world has long been miftaken in afcribing great power to the imagination of the female, whereas from this account of it, the real power of imagination, in the act of generation, belongs folely to the male. See Sect. XII. 3. 3. It may be objected to this theory, that a man may be fuppof- ed to have in his mind, the idea of the form and features of the female, rather than his own, and therefore there fhould be a greater number of female births. On the contrary, the general idea of our own form occurs to every one almoit perpetually, and is termed confcioufnefs of our exigence, and thus may ef- fect, that the number of males furpaffes that of females. See Sect. XV". 3. 4, and XVIII. 13. And what further con- firms this idea is, that the male children moil frequently Vol. I. E e e re&mhji 4io GENERATION. Sect. XXXIX. 6. 4. rcfemble the father in form, or feature, as well as in fex •, and the female mod frequently refemble the mother, in feature, and form, as well as in fex. It may again be objected, if a female child fometimes refem- bles the father, and a male child the mother, the ideas of the father, at the time of procreation, mud fuddenly change from himfelf to the mother, at the very inflant, when the embryon is fecreted or formed. This difficulty ceafes when we confider, that it is as eaiv to form an idea of feminine features with male organs of reproduction, or of male features with female ones, as the contrary ; as we conceive the idea of a fphinx or mer- maid as eafdy and as diftinctly as of a woman. Add to this, that at the time of procreation the idea of the male organs, and of the female features, are often both excited at the fame time, by contact, or by vifion. I afk, in my turn, is the fex of the embryon produced by ac- cident ? Certainly whatever is produced has a caufe ; but when this caufe is too minute for our comprehenfion, the effect is faid in common language to happen by chance, as in throwing a certain number on dice. Now what caufe can occafionally pro- duce the male or female character of the embryon, but the pe- culiar actions of thofe glands, which form the embryon ? And what can influence or govern thefe actions of the gland, but its affociations or catenations with other fenfitive motions ? Nor is this more extraordinary, than that the catenations of irritative motions with the apparent vibrations of objects at fea mould produce ficknefs of the ftomach ; or that a naufeous ftory fhould occafion vomiting. 4. An argument which evinces the effect of imagination on the firft rudiment of the embryon, may be deduced from the production of fome peculiar monfters. Such, for inflance, as thofe which have two heads joined to one body, and thofe which have two bodies joined to one head ; of which frequent exam- ples occur amongft our domefticated quadrupeds, and poultry. It is abfurd to fuppofe, that fuch forms could exift in primordial germes, as explained in No. IV. 4. of this fection. Nor is it poffible, that fuch deformities could be produced by the growth, of two embryons, or living filaments ; which fhould afterwards, adhere together ; as the head and tail part of different polypi are faid to do (Blumenbach on Generation. Cadell, London) y fince in that cafe one embryon, or living filament, mufl have begun to form one part firft, and the other another part iirlt. But fuch monftrous conformations become lefs difficult to comprehend, when they are confidered as an effect of the im- agination, as before explained, on the living filament at the time a* Sect. XXXIX. 6. 5. GENERATION. 4 1 1 of its fecretion \ and that fuch duplicature of limbs was pro- duced by accretion of new parts, in confequence of propenli- ties, or animal appetencies, thus acquired from the male parent. For inftance, I can conceive, if a turkey-cock mould behold a rabbit, or a frog, at the time of procreation, that it might hap- pen, that a forcible or even a pleafurable idea of the form of a quadruped might fo occupy his imagination, as to caufe a tenden- cy in the nafcent filament to refemble fuch a form, by the appo- rtion of a duplicature of limbs. Experiments on the production of mules and monfters would be worthy the attention of a Spal- lanzani, and might throw much light upon the fubject, which at prefent muft be explained by conjectural analogies. The wonderful effect of imagination, both in the male and female parent, is (hewn in the production of a kind of milk in the crops both of the male and female pigeons after the birth of their young, as obferved by Mr. Hunter, and mentioned before. To this mould be added, that there are fome inftances of men having had milk fecreted in their breads, and who have given fuck to children, as recorded by Mr. BufFon. This effect of imagination, of both the male and female parent, feems to have been attended to in very early times ; Jacob is faid not on- ly to have placed rods of trees, in part (tripped of their bark, fo as to appear fpotted, but alfo to have placed fpotted lambs before the flocks, at the time of their copulation. Geneiis, chap. xxx. verfe 40. 5. In refpect to the imagination of the mother, it is diffi- cult to comprehend, how this can produce any alteration in the fetus, except by affecting the nutriment laid up for its firft re- ception, as defcribed in No. V. 2. of this fection, or by affect- ing the nourifhment or oxygenation with which (lie fupplies it afterwards. Perpetual anxiety may probably affect the fecre- tion of the liquor amnii into the uterus, as it enfeebles >the whole fyftem ; and fudden fear is a frequent caufe of mifcar- riage \ for fear, contrary to joy, decreafes for a time the action of the extremities of the arterial fyftem ? hence fudden pale- nefs fucceeds, and a fhrinking or contraction of the veffels of the Ikin, and other membranes. By this circumftance, I im- agine, the terminations of the placental veffels are detached from their adhefions, or infertions, into the membrane of the uterus ; and the death of the child fucceeds, and confequent mifcarriage. Of this I recollect a remarkable inftance, which could be af- cribed to no other caufe, and which I fhall therefore relate in few words. A healthy young woman, about twenty years of age, had been about five months pregnant, and going down in- to 4 1 2 GENERATION. Sect. XXXIX. 6. 6\ to her cellar to draw fome beer, was frighted by a fervant boy ftartirig up from behind the barrel, where he had concealed himfelf with defign to alarm the maid-fervant, for whom he miftook his miflrefs. She came with difficulty up flairs, began to flood immediately, and mifcarried in a few hours. She has fmce borne feveral children, nor ever had any tendency to mif- carry of any of them. In refpc£f. to the power of the imagination of the male over the form, colour, and fex of the progeny, the following in- f lances have fallen under my obfervation, and may perhaps be found not very unfrequent, if they were more attended to. I am acquainted with a gentleman, who has one child with dark hair and eyes •, though his lady and himfelf have light hair and eyes ; and their other four children are like their parents. On cbferving this diflimilarity of one child to the others he allured me, that he believed it was his own imagination, that produced the difference ; and related to me the following (lory. Ke laid, that when his lady lay in of her third child, he became attached to a daughter of one of his inferior tenants, and offer- ed her a bribe for her favours in vain ; and afterwards a greater bribe, and was equally unfuccefsful ; that the form of this girl dwelt much in his mind for fome weeks, and that the next child, which was the dark-eyed young lady above mentioned, was ex- ceedingly like, in both features and colour, to the young woman who refufed his addrefTes. To this inftance I mufl add, that I have known two families, in which, on account of an intailed eflate in expectation, a male heir was moft eagerly defired by the father ; and on the con- trary, girls were produced to the ieventh in one, and to the ninth in another ; and then they had each of them a fon. I conclude, that the great defire of a male heir by the father produced rath- er a difagreeable than an agreeable fenfation ; and that his ideas dwelt more on the fear of generating a female, than on the pleaf- urable fenfations or ideas of his own male form or organs at the time of copulation, or of the fecretion of the femen ; and that" hence the idea of the female character was more prefent to his mind than that of the male one •, till at length in defpair of gen- erating a male thefe ideas ceafed, and thofe of the male charac- ter prefided at the genial hour. 6. Hence I conclude, that the acl: of generation cannot ex- ift without being accompanied with ideas, and that a man muff, have at that time either a general idea of his own male form, cr of the form of his male organs ; or an idea of the female form, or of her organs ; and that this marks the fex, and the peculiar refemblances of the child to either parent. From whence it would Sect. XXXIX. 7. 1. GENERATION. 4I3 would appear, that the phalli, which were hung round the necks of the Roman ladies, or worn in their hair, might have effect in producing a greater proportion of male children ; and that the calipxdia, or art of begetting beautiful children, and of pro- creating either males or females, may be taught by affecting the imagination of the male-parent ; that is, by the fine extremities of the femim.J glands imitating the actions of the organs of fenfe either of fight or touch. But the manner of accomplishing this cannot be unfolded with fufficient delicacy for the public eye \ but may be worth the attention of thofe, who are ferioufly in- terefted in the procreation of a male or female child. Recapitulation, VII. 1. A certain quantity of nutritive particles are produ- ced by the female parent before impregnation, which require no further digeftion, fecretion, or oxygenation. Such are feen in the unimpregnated eggs of birds, and in the unimpregnated feed-vefTels of vegetables. 2. A living filament is produced by the male, which being mferted amid ft thefe firft nutritive particles, is flimulated into action by them ; and in confequence of this action, fome of the nutritive particles are embraced, and added to the original liv- ing filament ; in the fame manner as common nutrition is per- formed in the adult animal. 3. Then this new organization, or additional part, becomes flimulated by the nutritive particles in its vicinity, and fenfation is now fuperadded to irritation ; and other particles are in con- fequence embraced, and added to the living filament ; as is feen in the new granulations of flefh in ulcers. By the power of aflbciation, or by irritation, the parts alreadv produced continue their motions, and new ones are added by fenfation, as above mentioned •> and laltly by volition, which Iaft fenforial power is proved to exifl in the fetus in its maturer age,.becaufe it has evidently periods of activity and of fleeping ; which laft is another word for a temporary fufpenfion of volition. The original living filament may be conceived to pofTefs a power of repulfmg the particles applied to certain parts of it, as well as of embracing others, ,\vhich ftimulate other parts of it ; as thefe powers exilt in different parts of the mature animal ; thus the mouth of every gland embraces the particles or flu which fuit its appetency ; and its excretory duct repulfes thofe particles, which are difagreeable to it. 4. Thus the outline or miniature of the new animal is pro- duced gradually, but in no great length of time ; becaufe the original 4i4 GENERATION. Sect. XXXIX. 7. c. original nutritive particles require no previous preparation by di- geftion, fecretion, and oxygenation : but require fimply the fe- lection and apportion, which is performed by the living fila- ment. Mr. Blumenbach fays, that he porTefles a human fetus of only five weeks old, which is the fize of a common bee, and has all the features of the face, every finger, and every toe com- plete ; and in which the organs of generation are diftinctly feen. P. 76. In another fetus, whofe head was not larger than a pea, the whole of the bafis of the (kull with all its depreflions, aper- tures, and procefTes, were marked in the moil fharp and diftinct manner, though without any ofhfication. lb. 5. In fome cafes by the nutriment originally depofited by the mother the filament acquires parts not exactly fimilar to thofe of the father, as in the production of mules and mulattoes. In other cafes, the deficiency of this original nutriment caufes defi- ciencies of the extreme parts of the fetus, which are laft form- ed, as the fingers, toes, lips. In other cafes, a duplicature of limbs, is caufed by the fuperabundance of this original nutritive fluid, as in the double yolks of eggs, and the chickens from them with four legs and four wings. But the production of other monfters, as thofe with two heads, or with parts placed in wrong fituations, feems to arife from the imagination of the father being in fome maiiner imitated by the extreme veflels of the feminal glands 5 as the colours of the fpots on eggs, and the change of the colour of the hair and feathers of animals by do- meilication, may be caufed in the fame manner by the imagina- tion of the mother. 6. The living filament is a part of the father, and has there- fore certain propenfities, or appetencies, which belong to him ; which may have been gradually acquired during a million of generations, even from the infancy of the habitable earth *, and which now pofielles fuch properties, as would render, by the appofition of nutritious particles, the new fetus exactly fimilar to the father ; as occurs in the buds and bulbs of vegetables, and in the polypus, and taenia, or tape-worm. But as the firft nutriment is fupplied by the mother, and therefore refembles fuch nutritive particles, as have been ufed for her own nutriment or growth, the progeny takes in part the likenefs of the mother. Other fimihrities of the excitability, or of the form of the male parent, fuch as the broad or narrow ihoulders, or fuch as con- ftitute certain hereditary difeafes, as fcrofula, epilepfy, infanity, have their origin produced in one or perhaps two generations ; as in the progeny of thofe who drink much vinous fpirits ; arid thofe hereditary propenfities ceafe again, as I have obferved, if one or two fober generations fucceed m, otherwife the family becomes extinct. This Sect. XXXIX. 7.7. GENERATION. 4 1 5 This living filament from the father is alfo liable to have its propenfities, or appetencies, altered at the time of its production by the imagination of the male parent ; the extremities of the feminal glands imitating the motions of the organs of fenfe ; and thus the fex of the embryon is produced j which may be thus made a male or a female by affecting the imagination of the father at the time of impregnation. See Sect. XXXIX. 6. 3. and 7. 7. After the fetus is thus completely formed together with its umbilical veffels and placenta, it is now fupplied with a dif- ferent kind of food, as appears by the difference of confiftency of the different parts of the white of the egg, and of the liquor amnii, for it has now acquired organs for digeftion or fecretion, and for oxygenation, though they are as yet feeble ; which can in fome degree change, as well as felect the nutritive particles, which are now prefented to it. But may yet be affected by the deficiency of the quantity of nutrition fupplied by the mother, or by the degree of oxygenation fupplied to its placenta by the maternal blood. The augmentation of the complete fetus by additional particles of nutriment is not accomplifhed by diftention only, but by ap- portion to every part both external and internal ; each of which acquires by animal appetencies the new addition of the particles which it wants. And hence the enlarged parts are kept fimilar to their prototypes, and may be faid to be extended ; but their extenfion muft be conceived only as a neceffary confequence of the enlargement of all their parts by apportion of new particles. Hence the new appofition of parts is not produced by capilla- ry attraction, becaufe the whole is extended ; whereas capillary attraction would rather tend to bring the fides of flexible tubes together, and not to diftend them. Nor is it produced by chemical affinities, for then a folution of continuity would fuc- ceed, as when fugar is diffolved in water ; but it is produced by an animal procefs, which is the confequence of irritation, or fenfation ; and which may be termed animal appetency. This is further evinced from experiments, which have been inftituted to fhew, that a living mufcle of an animal body re- quires greater force to break it, than a fimilar mufcle of a dead body. Which evinces, that befides the attraction of cohefion, which all matter poffeffes, and befides the chemical attractions of affinities, which hold many bodies together, there is an ani- mal adhefion, which adds vigour to theie common laws of the inanimate world. 8. At the nativity of the child it depofits the placenta or plls, and by expanding its lungs acquires more plentiful oxyge- nation 4i<* GENERATION. Sect. XXXIX. 7. nation from the currents of air, which it mufl now continue perpetually to refpire to the end of its life ; as it now quits the liquid element, in which it was produced, and like the tadpole, when it changes into a frog, becomes an aerial animal. 9. As tlu habitable parts of the earth have been, and con- tinue to be, perpetually increafing by the produftion of fea- fliell-s and corallines, and by the recrements of other animals, and vegetables ; (o from the beginning of the exigence of this terraqueous globe, the animals, which inhabit it, have conftant- ly improved, and are (till in a date of progreflive improvement. This idea of the gradual generation of all things feems to have been as familiar to the ancient philofophers as to the mod- ern ones.; and to have given rife to the beautiful hieroglyphic figure of the wgorav mv, or fir ft great eg^y produced by night, that is, whofe origin is involved in obfeurity, and animated by i£*c, that is,- by Divine Love ; from whence proceeded all things which ex id. Appendix. VIII. i . Since the former publication of the preceding Sec- tion on Generation, I have been induced in my treatife on Phyt- ologia, to give more attention to the lateral or folitary genera- tion of vegetables in the production of their buds, hoping from thence to throw fome light on their fexual generation in the pro- duction of feeds ; and in coniequence on the propogation of more perfect animals, which I ihall here relate, believing that it may intereft the philofophical reader, obferving only, that by the vegetable facls here attended to, I am now induced to be- lieve, that the embryons of complicate animal and vegetable bodies are not formed from a fingle filament as above delivered ; but that their ftructure commences in many parts at the fame time, though it is probable, that the moft fnnple or firil exordi- um of animation was begun by a fingle filament, and continues to do fo in the fpontaneous production of the fmalleft micro- fcopic animals, which do not appear to have been generated by other animalcula fimilar to themfelves, as further fpoken of in No. 11. 5. of this Section. 1. It is (hewn at large in the work above mentioned, that every bud of a tree is an individual vegetable, and confifts of the plumula or leaf at its fummit, of a long caudex extending from this fummit down wands to the earth, forming a filament of the bark, and laftly of radicles beneath the foil : it is alfo fhewn, that every bud poflelTes the power of germination or reproduc- , not onlv in the axilla of the leaf, which is moft common, but Sect. XXXIX. 8. i. GENERATION. 41? but from any part of the long caudex gemmae above mentioned, as appears from new buds fpringing out from any part of the bark, when the top of a branch is cut off. Now if a fcion of a nonpareil apple be ingrafted on a crab •ftock, and a golden-pippin be ingrafted on the nonpareil, what happens ? — The caudex of the bud of the golden-pippin confifts of its proper abforbent veffels, arteries, and veins, till it reaches down to the nonpareil ftock ; and then the continuation of its caudex downwards confifts of veffels fimilar to thofe of the non- pareil ; and when its caudex defcends Mill lower, it confifts of veffels fimilar to thofe of the crab-ftock, The truth of this is (hewn by two circumftances ; firft, be- caufe the lower parts of this compound tree will occafionally put forth buds fimilar to the original ftock. And fecondly, be- caufe in fome ingrafted trees, where a quick-growing fcion has been inferted into a ftock of flower growth, as is often feen in old cherry-trees, the upper part of the trunk of the tree has become of almoft double the diameter of the lower part. Both which occurrences (hew, that the lower part of the trunk of the tree continues to be of the fame kind, though it muft have been fo repeatedly covered over with new circles of wood, bark, and cuticle. Now as the caudex of each bud, which panes the whole length of the trunk of the tree, and forms a communication from the upper part or plumula, to the lower part or radicle, muft: confift in thefe doubly ingrafted trees of three different kinds of caudexes, refembling thofe of the different ftocks or fcions ; we acquire a knowledge of what may be termed a lateral or pater- nal mule, in contradiftinclion to a fexual mule. For as in thefe trees thus combined by ingraftrr^nt every bud has the upper part of its caudex that of a golden-pippin, the middle part of it that of a nonpareil, and the lower part of it that of a crab ; if thefe caudexes, which conftitute the filaments of the bark could be Separated intire from the tree with their plumules and radi- cles, they would exhibit fo many lateral or paternal mules, con- fiding of the connected parts of their three parents ; the plu- mula belonging to the upper parent, and the radicle to the low- er one, and the triple caudex^to them all. A feparation of thefe buds from the parent plant is faid to have been obferved by Mr. Blumenbach, in the conferva fonti- nalis, a vegetable which confifts of fmall ftiort flender threads, which grow in our fountains, and fix their roots in the mud. He obferved by magnifying glaffes, that the extremities of the threads fwell, and form fmall tubera or heads j which gradually feparate from the parent threads, attach themfelves to the Vol. I. F f f ground? 4 1 8 GENERATION. Sect. XXXIX. 8. 2, ground, and become perfect vegetables ; the whole progrefs of their formation can be obferved in forty-eight hours. Obfer- vations on plants by Von Uflar. Creech, Edinb. 2. The lateral propagation of the polypus found in our ditches in July, but more particularly that of the hydra ftentorea, is won- derfully analogous to the above idea of the lateral generation of vegetables. The hydra ftentorea, according to the account of Monf. Trembley, multiplies itfelf by fplitting lengthwife ; and in twenty-four hours thefe divifions, which adhere to a common pedicle, refplit, and form four diftincl: animals. Thefe four in an equal time fplit again, and thus double their number daily ; till they acquire a figure fomewhat refembling a nofegay. The young animals afterwards feparate from the parent, attach them- felves to aquatic plants, and give rife to new colonies. Another curious animal fact is related by Blumenbach in his Treatiie on Generation concerning the frefh water polypus. He cut two of them in halves, which were of different colours, and applying the upper part of one to the lower part of the other by means of a glafs tube, and retaining them thus for fome time in contact with each other, the two divided extremities united, and became one animal. The facil union of the divided halves of different polypi is alfo afferted by Mr. Adams. Treatife on Microfcopes. The intelligent reader has already anticipated me in applying thefe wonderful modes of lateral animal reproduction and con- junction, to trfe lateral propagation and ingraftment of vegeta- bles. The junction of the head part of one polypus to the tail- part of another is exactly reprefented by the ingraftment of a icion on the ftock of another tree, the plumula or apex of each bud with the upper part of iti caudex joins to the long caudex of the ftock, which pafhng down the trunk terminates in the radicles of it. And if this compound vegetable could be fepa- rated longitudinally from the other long filaments of the bark in its vicinity, like the fibres of the bark of the mulberry tree pre- pared at Otaheite, or as the bark of hemp and flax are pre- pared in this country, as the young ones of the hydra ftentorea ieparate from their parents, it might claim the name of a lateral or paternal mule, as above mentioned. 3. It hence appears, that every new bud of a tree, where two icions have been inferted over each other on a ftock, if it could be feparated from the plume to the radicle, muft confift of three different kinds of caudex ; and might therefore be called a triple lateral mule. And that hence it follows, that every part of this new triple caudex muft have been feparated or fecreted laterally from the adjoining part of the trunk of the tree ; and that it could 1 Sect. XXXIX. 8. 4. GENERATION. 4i9 could not be formed, as I formerly believed, from the roots of the plume of the bud defcending from the upper part of the cau- dex of it to the earth. A circumftance of great importance in the inveftigation of the curious fubject of the lateral generation of vegetables, and of infects. One might hence fufpect, that if Blumenbach had attended to the propagation of the polypus, which he had compofed of tw© half polypi, that the young progeny might have poffeffed two colours refembling the compound parent, like the different cau- dexes of ingrafted trees ; an experiment well worthy repeated obfervation. 4. Another animal fact ought alfo to be here mentioned, that many infects, as common earth worms as well as the polv- pus, are faid to poffefs fo much life throughout a great part of their fyflem j that they may be cut into two or more pieces without deflroying them ; as each piece will acquire a new head, or a new tail, or both, and the infect will thus become multi- plied ! How exactly this is refembled by the long caudex of the buds of trees ; which poffefs fuch vegetable life from one ex- tremity to the other, that when the head or plume is lopped off, it can produce a new plume, and when the lower part is cut off, it can produce new radicles ; and may be thus wonderfully multiplied ! This curious vegetable phenomenon is worthy our attention and remembrance ; for as each filament of the new bark of a tree conft itutes a caudex of an embryon bud ; when the fum- mtt of a twig is lopped off, which contained the plumules or em- brypn leaves of many of them ; each embryon caudex can gen- erate new plumules or embryon leaves ; and new radicles, when the lower part of a twig is cut off, and the upper part planted ; which demonftrates, that the primary parts of a vegetable em- bryon may produce fecondary parts ; and that hence it is not neceffary, that the whole of an animal fetus mould be formed at the fame time. 5. Hence we acquire fome new and important ideas con- cerning the lateral generation of vegetables, and which may probably contribute to elucidate their fexual generation. Thefe are, firit, that the parts of the long caudex of each new bud of an ingrafted tree, and confequently of all trees, are feparated or fecreted from the correlpondent or adjoining parts of the long caudex of the lafl year's bud, which was its parent. And not that it confifts of the roots of each new bud fhot down from the piumula or apex of it •, as I formerly fuppofed. And that thefe various molecules or fibrils fecreted from the caudex of the laft vear's buds adjoin and grow together beneath the cuticle of 420 GENERATION. Sect. XXXIX. 8. 6, of the trunk of the tree ; the upper ones forming the plumula of the new bud, which is its leaf or lungs to acquire oxygen from the atmofphere •, and the lower ones forming the radicles of it, which are abforbent veiTels to acquire nutriment from the earth. Secondly, that every part of the caudex of an ingrafted tree, and confequently of all trees, can generate or produce a new plumula, when the upper part of it is ftrangulated with a wire or cut off *, or otherwife when it is fupplied more abundantly with nutriment, ventilation, and light. And that each of thefe new buds thus produced refembles that part of the flock in com- pound trees, where it arifes. Thus in the triple tree above mentioned a bud from the upper part of the long caudexes, which form the filaments of the bark, would become a golden- pippin branch, a bud from the middle part of them would become a nonpareil branch, and a bud from the lower part a crab branch, Thirdly, another wonderful property of this lateral mule progeny of trees compounded by ingraftment confifts in this, that the new mule may confift of parts from three or four or many parents ; when fo many different fcions are ingrafted on each other, whence a queftion may arife, whether a mixture of two kinds of anther-dull previous to its application to the ftigma of flowers might not produce a threefold mule partaking o£ the likenefs of both the males ? 6. On this nice fubject of reproduction, fo far removed from common apprehenfion, the patient reader will excufe a more prolix investigation. The attraction of all matter to the centres of the planets, or of the fun, is termed gravitation, that of par- ticular bodies to each other is generally called chemical affinity ; to which the attractions belonging to electricity and magnetiim appear to be allied. In thefe 'latter kinds of attraction two circumftances feem to be required, firft, the power to attract poflefled by one of the bodies, and feconrily, the aptitude to be attracted poflefled by the other. Thus when a magnet attracts iron, it may be faid to porTefs a fpecific tendency to unite with iron ; and the iron may be faid to poffefs a fpecific aptitude to be united with the magnet. The former appears to refide in the magnet, becaufe it can be deprived of its attractive power, which can alfo be reftorr- ed to it. And the iron appears to poffefs a fpecific aptitude to be unite'd with the magnet, becaufe no other metal will approach it. In the fame manner a rubbed glafs tube or a rubbed ftick of fealing wax may be faid to poffefs a fpecific tendency to unite ith a light ftraw, or hair, and die draw or hair to poffefs a fpecific Sf.ct. XXXIX. 8. 7. GENERATION. 42 r fpecific aptitude to unite with the rubbed glafs or fealing wax ; becaufe the lpecific attraction to the rubbed glafs or fealing wax can be withdrawn or reftored ; to which may be added, that fome chemical combinations may arife from the fingle attrac- tion of one body, and the aptitude to be attracted of another. Or they may be owing to reciprocal attractions of the two bodies, as in what is termed by the chemifts double affinity, which is known to be fo powerful as to feparate thofe bodies, which are held together by the fimple attraction- probably of one of them to the other ; which other pofYeiTes only an apti- tude to be attracted by the former. It is probable, that in fome of the mod fimple combinations of the particles of inanimate matter, two of them may be ftrongly united by reciprocal attractions to each other ; that in other fimple combinations two particles may be held together, though lefs firmly, by the attraction of one and the aptitude to be attracted o,f the other. Thus I fufpect that carbon and oxygen rufli together by their reciprocal attractions producing explofion, and being afterwards not eafily feparable ; while azote or nitrogen is lefs firmly united with oxygen by the attraction of one of them, and only the aptitude to be attracted of the other. If this cir- cumftance could be nicely ascertained, the theory of chemical affinities might poffibly advance a ftep further in the explana- tion of fome difficult phenomena, as of the heat generated in the explofion of various materials, with which oxygen is more loofely united, when applied to ignited carbon ; as of the acid of nitre, and feveral metallic oxydes ; as well as of the general circumftances of combuftion and inflammation, as of phofpho- rus in the atmofphere, and of oil of cloves with nitrous acid. 7. The above account of the tendencies to union of unor- ganized or inanimate matter is not given as a philofophical analogy, but to facilitate our conception of the adjunctions or concretions obfervable in organized or animated bodies ; which conftitute their formation, their nutrition, and their growth. Thefe may be divided into two kinds ;.fir(l the junction or union of animated bodies with inanimate matter, as when fruit or nefh is fwallowed into the ftomach, and becomes abforbed by the lacteals; and the fecond, where living particles coalefce or concrete together ; as in the formation, nutrition, or conjunc- tion of the parts of living animals. In refpect to the former the animal parts, as the noflrils and palate, poflefs an appetency, when ftimulated by the icent and flavour of agreeable food, to unite themfelves with it ; and the inanimate material pofiefles an aptitude to be thus united with the animal organ. The fame occurs, when the food is fwal- lowed 422 GENERATION. Sect. XXXIX. 8. 3. lowed into the flomach ; the mouths of the lacteal veflels be- ing agreeably ttimulated pofTefs an appetency to abforb the par- ticles of the digefting mafs •, which is in a fituation of under- going chemical changes, and pofTefles at fome period of them an aptitude to ftimulate, and to be united with the mouths of the abforbent lafteals. But when thefe abforbed particles of inanimate matter have been circulated in the blood, they feem gradually to obtain a kind of vitality ; whence Mr. John Hunter, and I believe fome antient philosophers, and the divine Mofes, aiTerted, that the blood is alive ; that is, that it pofTefTes fome degree of organi- zation, or other properties, different from thole of inanimate matter ; which are not producible by any chemical procefs, and which ceafe to exift along with the life of the animal. Hence for the purpofe of nutrition there is reafon to fufpect, that two circumftances are neceflary, both dependent upon life, and con- fequent activity ; thefe are firft an appetency of the fibrils of the fixed organization, which wants nutrition ; and fecondly a propenlity of the fluid molecules exifting in the blood, or fe- creted from it, to unite with the organ now ftimulated into ac- tion. So that nutrition may be faid to be effected by the em- brace or coalefcence of the fibrils, which pofTefs nutritive appe- tencies, with the molecules, which pofTefs nutritive propenfities, or in other words of particles, which pofTefs reciprocal appeten- cies to embrace each other. 8. If the philofopher, who thinks on this fubject, fhould not be inclined to believe, that the whole of the blood is alive, he cannot eaiily deny life to that part of it, which is fecreted by the organs of generation, and conveys vitality to the new em- bryon, which it produces. Hence though in the procefs of nu- trition the activity of two kinds of fibrils or molecules may be fufpected, yet in the procefs of the generation of a new vegeta- ble or animal, there feems great reafon to believe, that both the combining and combined particles are endued with vitality ; that is, with fome degree of organization or other properties not exifting in inanimate matter, which we beg leave to denom- inate fibrils with formative appetencies, and molecules with formative propenfities ; as the former may feem to pofTefs a greater degree of organization than the latter. And thus it appears, that though nutrition may be conceived to be produced by the animated fibrils of an organized part be- ing fh.Tiulated into action by inanimate molecules, which they 'hen embrace ; and may thus be popularly compared to the timple attractions of chemiliry ; yet that in the production of ;: new einbryon, whether vegetable or animal, both the fibrils with Sect. XXXIX. 8. 9. GENERATION. 42 •1 with formative appetencies and the molecules with formative pro- penfities reciprocally ftimulate and embrace each other, and in- itantly coalefce; and may thus popularly be compared to the recip- rocal attractions of fome of the atoms of inanimate matter, or to the double affinities of chemiltry. But there are animal facts, which may be compared to both thefe, and are thence more philofophically analagous to them ; and thefe are the two great iupports of animated nature, the paflions of hunger of and love. In the former the appetency refides only in the ftomach, or per- haps in the cardia ventriculi, but the objecT: confiits of inani- mate matter ; in the latter there exift reciprocal appetencies and propenfities in the male and female, which mutually ex- cite them to embrace each other. Two other animal facls are equally analogous ; the third, which refides at the upper end of the efophagus, and though it pofTefles appetency itfelf, its ob- ject is inanimate matters ; but in lattefcent females, when they give fuck to their young, there exifts a reciprocal appetency in the mother to part with her milk, and in the young offspring to receive it. This then finally I conceive to be the manner of the produc- tion of the lateral progeny of vegetables. The long caudex of an exifting bud of a tree, which conftitutes a fingle filament of the prefent bark, is furnifhed with glands numerous as the perfpi- rative or mucous glands of animal bodies \ and that thefe are of two kinds, the one fecreting from the vegetable blood the fibrils with formative appetencies, correfpondent to the mafculine fe- cretion of animals ; and the other fecreting from the vegetable blood the molecules with formative propenfities, correfpon- dent to the feminine fecretion of animals, and then that both thefe kinds of formative particles are depofited beneath the cu- ticle of the bark along the whole courfe of it, and inftantly em- brace and coalefce, forming a new caudex along the fide of its parent, with vegetable life, and with the additional powers of nutrition, and of growtfi. 9. This then is the great fecret of nature. More living particles, fome with appetencies, and fome with propenfitie-, are produced by the powers of vitality in the fabrication of the vegetable blood, than are necefTary for nutrition, or for the res- toration of decompofing organs. Thefe are fecreted by differ- ent glands, and detruded externally, and produce by their com- bination a new vital organization beneath the cuticles of trees over the old one. Thefe new combinations of vital fibrils and molecules acquire new appetencies, and fabricate molecules with new propenfities ; and thus poffefs the power of forming the leaf or lungs at one extremity of the new caudex ; and the radicles 424 GENERATION. ' Sect. XXXIX. 8. i o; radicles or abforbent veffelsat the other end ; and fome of them* as in the central buds, which terminate the branches, finally form the fexual organs of reproduction, which confliitute the flower ', all which are fecondary parts of the new embryon or fetus, as fhewn in number 9. 4. of this feelion. That new organizations of the growing fyftem acquire new appetencies appears from the production of the pafhonfor gen- eration, as foon as the adapted organs are complete, and alfo from the variation of the .palate, or defire for particular kinds of food, as we advance in life, as from milk to flefh \ thus as a popular allufion, not as a philofophtcal analogy, we may again be allowed to apply to the combinations of chemiflry. Where two different kinds of particles unite, as acids and alkalies, a third fomething is produced, which poffeffes attractions diffimi- lar to thofe of either of them. And that new organizations form new molecules, appears from the fecretions of the feminal and uterine glands, when they have acquired their maturity > and from the pectoral ones of lactefcent females. 10. In the lateral propagation of vegetable buds, as the fu- perfluous fibrils or molecules, which were fabricated in the blood, or detached from living organs, and polTefs nutritive or formative appetencies and propenfities ; and v/hich were more abundant, than were required for the nutrition of the parent vegetable bud, when it had obtained its full growth, were fe- creted by innumerable glands on the various parts of its furface beneath the general cuticle of the tree, and there embracing and coalefcing, form a new embryon caudex, which gradually pro- duces a new plumula and radicles. And as the different parts of the new caudex of a compound tree refemble the parts of the parent caudex, to which it adheres, this important circum- ftance is {hewn beyond all doubt, that different fibrils or mole- cules were detached from different parts of the parent caudex to form the filial one. So in the fexual propagation of vegetables the fuperfluous liv- ing fibrils or molecules detached from various parts of the fyf- tem, and floating in the blood, appear to be fecreted from it by two kinds of glands only, thofe which conititute the anthers, and thofe which conititute the pericarp of flowers. By the for- mer I fuppofe the fibrils with formative appetencies and with nutritive appetencies to be fecreted ; and by the latter the mole- cules with formative and with nutritive propenfities. After- wards, that thefe fibrils with formative and nutritive appeten- cies become mixed in the pericarp of the flower with the cor- rci'pomlent molecules with formative and nutritive propenfities, and Sect. XXXIX. 8. u. GENERATION. 4 - and that a new embryon is inftantly produced by their recipro- cal embrace and coalefcence. And that parts of this new organization afterwards acquire new appetencies, and form new molecules, and thus gradually produce other parts of the growing feed, which do not at fir ft appear, as the plumula, radicles, cuticle, and the glands of re- production in the pericarp and anthers, which correfpond in the animal fetus to the lungs, interlines, cuticle, and the organs, which diftinguifh the fexes, and are their parts of fecondary formation. If fecondary parts of a vegetable embryon were not fabrica- ted from the primary parts, or firit rudiments of it, the flowers of the clafs dicecia of Linneus could not produce both m and female feeds, as the male and female organs of reproduction re fide on different plants. For as the male plants produce buds fimilar to themfelves, which may be termed male buds •, and the female plants produce buds fimilar to themfelves, which may be termed female buds, it would feem impoffible for the flowers to generate female feeds according to the theory cf re- production above delivered. As the male, not being an her- maphrodite, cannot be fuppofed to fecrete any fibrils with ap- petencies proper to produce female organs, as no fuch can ex- ift in his blood, which muft therefore be fabricated afterwards by the new appetencies acquired by the new organizations of the growing embryon. /i 1. From this new doctrine of a three-fold vegetable mule by lateral propagation, as the new bud of a tree, which has had two fcions ingrafted on it one above another ; in which it is in- conteftibly fhewn, that different fibrils or molecules are detach- ed from different parts of the parent caudex to form the filial one, which adheres to it ; we may fafely conclude, as it is de- ducible from the ftrongeft analogy, that in the production of fexual mules, fome parts of the new embryon were produced by, or detached from, fimilar parts of the parent, which they refemble. And that as thefe fibrils or molecules floated in the circulating blood of the parents, they were collected feparate- ly by appropriated glands of the male or female j and that fi- nally on their mixture in the matrix the new embryon was gen- erated, refembling in fome parts the form of the father, and in other parts the form of die mother, according to the quantity or activity of the fibrils or molecules at the time of their con- junction. And lafliy, that various parts of the new organizations after. wards acquired new appetencies, and formed molecules with nev/ propenfities, and thus gradually produced other lecond; Vol, I. Ggc ; r* 1 1 426 GENERATION. Sect. XXXIX. 9. u parts 01 the growing fetus, as the fkin, nails, hair, and the or- gans which diftinguilh the fexes. If the molecules fecreted by the female organ into the peri- carp of flowers, or into the ovary of animals, were fuppofed to coniift ot only unorganized or inanimate particles ; and the fi. brils fecreted by the male organ only to poiTefs formative appe- tencies to fele£l and combine with them ; the new embryon mud probably have always refembled the father, and no mules could have had exiftence. But by the theory above delivered it appears, that the new offspring, both in vegetable and animal reproduction, whether it be a mule or not, mud fometimes more refemble the male parent, and fometimes the female one, and fometimes to be a combination of them both, as in the Epigram of Aufonius. Dum dubitat Natura marem, faceretne pucllam Fa&us es, O pulcher, pene puella, Puer ! IX. i. The foregoing remarks on vegetable generation are chiefly tranferibed from my work on Phytologia, Se£t. VII. and may be applied to animal reproduction ; fince from this analo- gy to the lateral propagation of vegetable buds, if we fuppofe, that redundant fibrils with formative appetencies are produced by, or detached from, various parts of the male animal, and cir- culating in his blood, are fecreted by adapted glands, and con- ilitute the feminal fluid *, and that redundant molecules writh formative aptitudes or propenfities are produced by, or detached from, various parts of the female, and circulating in her blood, are fecreted by adapted glands, and form a refervoir in the ova- ry ; and finally that when thefe formative fibrils, and forma- tive molecules, become mixed together in the uterus, that they coaleice or embrace each other, and form different parts of the new embryon, as in the cicatricula of the impregnated egg ; we may more readily comprehend fome circumftances, which are difficult to underftand on any other fyftem of generation. It mud be obferved that this theory differs from that of M. Buffbn ; as he conceives the fame organized particles to exift in the generative fecretions both of the male and female par- ent •, whereas in this theory it is fuppofed, that particles com- pletely organized are too large to pais the glands of either fex, and that thofe, which are {een in the femen by microfcopes, are the confequence of the ftagnation of the fluid, as in the puftules 01 the itch, and in the liquid feces of dyfenteric patients. Hence fibrils with formative appetencies and the molecules wiih formative aptitudes or propenfities mult coalefce to produce the .'. rganization. Secondly Sect. XXXIX. 9. 1. GENERATION. 427 Secondly, in M. Buffon's theory the fetus is fuppofed to be inftantaneoufly produced all at once j whereas in our theory there is believed to exift a primary, and fecondary formation ; that is, that many effential parts, as the brain and the heart, are primarily produced from the congrefs of the fibrils with formative appetencies, and the molecules with formative aptitudes or pro- penfities ; and that thefe combinations acquire new appeten- cies, and produce or unite with molecules with new aptitudes, and thus generate other parts of fecondary formation, as ribs, fingers, inteftines, with the external form, and the glands, which conftitute the difference of .the fexes. One great objection to the theory delivered in the former part of this fection on generation is removed by this idea of the exiftence of formative fibrils, and formative molecules, which by their coalefcence generate various parts of the embryon at the fame time ; which is, that in fome monftrous or imperfect fetufes different parts only are produced, inftead of the whole ; and fuch parts as would not appear to be primary ones. Such are the teeth and hair, which have been found in moles or falfe conceptions, as they exift naturally at a diftance from the brain and heart, which are efteemed to be the centre of vitality, and are firft vifible in the embryon chick. Many other parts in monftrous births are faid to have been completely formed, where no brain or heart has exifted ; the production of which on oth- er ideas of generation cannot be explained ; unlefs it be fup- pofed, that an intire embryon had been at firft generated, all of which had perifhed, and had been abforbed, except the parts which conftitute the monftrous or imperfect fetus at its birth, which would be difficult to explain. Many inftances of very imperfect fetufes are recorded by Monf. J. J. Sue in his Rechearches fur la Vitalite •, and in the Comment, of Leipfic. I. 17. p. 528. M. Sue diffected a fetus of five months old, which had no head, nor cheft, nor ftomach, nor large inteftines, and yet the inferior half of the lower belly was complete, with the umbilical cord, male organs of genera- tion, and one complete inferior limb, of which a print is given in Magazin. Encycloped. 1797. Tl '.s monftrous fetus, which was only half of it formed, fhews, that the embryon is not al- ways produced from one beginning, but probably from many : as there was no brain or heart, the connection of nerves in the lower part of the fpine muft have ferved the purpofe of the former; and a junction of the large arteries and veins muft have ferved the purpofe of a heart, producing a circulation like that in the liver, or in the aorta and vena cava of fifti. For a previous production and reabforption of the other more eflen- tial GENERATION. Sect. XXXIX. 9. i, il parts of tlic fetus, as the brain and heart, with all the upper parts of the body, and mteftines, would feem to be attended with iliil greater difficulties. The mi flake of conceiving the embryon to begin its forma- tion in one point only might more readily be fallen into from our habitually confidering an animal as an individual entity ; which it fecms not to be, till an union of the nerves from every part is formed in the common fenforium, and produces a gener- al feuiibility, which is thus diftinguiihed from irritability, which may refide in parts even when detached from the fyftem, as is fcen in the contractions of the heart of a viper taken out oi the body, or of limbs recently cut off. 2. Another thing difficult to conceive from thofe theories, which fuppofed the firft rudiment to confift of a fmgle entity, was to anfwer the curious queflion,. whether the brain, or heart ;'nd arteries were fir ft formed ; as the motions of the arterial iyftem previously everted feem to have been necelTary for the •cere t ion of fenforial power in the brain, and converfely thofe; motions of the arterial fyftem feem previouily to require the fenforial power derived from the brain. This difficulty vanifhes, when we believe, that many parts of tlip young embryon can be begun at the fame time, as various formative fibrils and formative molecules coalefcc, as they come into contact with each other ; and thus the rudiments of the brain and of the heart may be fabricated at the fame in (taut of time. 3. If fibrils with formative appetencies, and molecules with fdrmative aptitudes or propenfities exift in the circulation both or males and females, why do they not coalefcc there ? This ins an unanfvvevable objection to M. Buffon's theory, who holds, that organic particles exift in the circulation ; but in the tern above delivered, no organic particles exift in the blood in their combined ftate ; and hence no microfcopic animalcula are n in blood recently drawn, though they may appear after fomc urs ftagnation ; but the formative fibrils only and formative olecules are believed to exift in the circulation j and that they not produce combinations there, as they cannot reft ; and as .h combinations would be too large to pafs the capillary vef- fels of the aorta, and of the pulmonary artery, and of all the ands, and mult there be perpetually ditlevered, if they could evioufly formed in the larger veiTels. 4. If limiiar organized particles were fecreted by the fexual mds of the male and alio of the female, why do they not pro- Jr.cc parts, or rudiments, of an embryon in the male or female reiervoirs without a reciprocal commixture. This is anotrn lanfwerabk objection to M. Buffon's theory, but not to that above Sect. XXXIX. 9. 5. GENERATION. 429 above delivered ; which latter fuppofes, that no organized par- ticles are lecreted either by the glands of the male or female ; but that the fibrils with formative appetencies are lecreted by the glands of the male, and the molecules with formative apti- tudes or propenfities are fecreted by thole of the female ; and that, when thefe combine, the organization commences. 5. If the whole of the embryon is iuppofed to be fynchron- oufly produced, which is faid almofl to be vifible in the cicatric- ula of the egg even before incubation, how can this happen from a commixture of any kind of particles deduced from both the male and female parents, if thofe particles are previoully de- tached from the various parts of their respective bodies ; fince no parts fimilar to the female organs can previoully exift in the male, nor any of thofe of the male organs previoully exiit in the female ? This fynchronous production of all the parts of the em- bryon is fuppofed by M. BufFon, and militates again!! his the- ory ; and if it was true, would equally militate againlt that above delivered ; but from all the hiitories of the beginning and growing fetus given by anatomifts there are parts of fecondary formation, as well as parts of primary formation ; thus the head and fpine of the back are firil feen both in the oviparous and vi- viparous embryon, and afterwards the lungs, ribs, limbs, nails, hairs, and feathers, and laft of all perhaps the glands which dif- tinguifh the fexes ; as thefe are the laft, which afterwards ar- rive at their maturity. This fecondary formation of parts is evinced in the long cau- dexes of the buds of trees, which form a filament of the bark ■, as from any part of this a new plumu'a or leaf, which is the lungs cf the embryon bud, can be produced, when the upper part of a branch is lopped off, as fhewn in No. 9. 4. of this fection ; and is further evinced in fome animals, as when a common earth-worm is cut in halves, the tail-part can produce a head-part, and the head-part can produce a tail-part ; and laftly, it is evinced from the power, which crabs poffefs of gen- erating a new leg, when one of them is accidentally broken off. This power is likewife poffeffed by the human body, as in the production of new teeth, and then of a fecond fet, and there are fome inftances on record, that a third fet of teeth have been fab- ricated in the jaw-bones of age. The power of formation of fecondary parts in the human fyf- tem is wonderfully fhewn by the following cafe, which is related by Mr. White in the Mancheiter Memoirs, Vol. I. p. 338. f* Some vears a^o I delivered a ladv of rank of a fine boy, who ha and the folitary mode of generation is fecondary to the produc- tion of the fmalleft microfcopic animals, which I fuppofe com- mence their e:;iftence in one point only, that is, by the produc- tion firft of a fingle living filament, which I formerly believed to be the general mode of propagation. This folitary mode of generation occurs in the production of the buds of all vegeta- bles •, and perhaps the moft imperfect vegetables, as truffles, and other fungi, are only propagated by buds to this day, not hav- ing yet acquired fexual organs, as leems alfo to occur in fome imperfect animals, as the polypi, hydra, and tenia. 3. Other vegetables have acquired an hermaphrodite ftate, and pofTefs external fexual organs, as in moft flowers -, but both the male and female organs acquire or produce their adapted fluids from the fame mafs of blood, and thus refemble hermaph- rodite infects, as fnails and worms. 4. Other vegetables have acquired a feparation of the fexes, either on the fame plant, as in the clafs of vegetables termed by LinneuSj moncecia, or on different plants, as in the clafs dioe- cia i Sect. XXXIX. i r . 5. GENERATION. 43 7 cia ; the buds of which may properly be called male or female vegetables, and differ in fome degree in their form and colour, like male and female animals ; and in this they refemble the larger animals, as their fexual glands acquire or produce their prolific fluids from different maffes of blood •, which is probably lefs cumberfome to the individual, than where both the fexual glands exift in one organized fyftem. In all thefe vegetable and animal modes of reproduction, I fuppofe the new embryon to begin in many points, and in com- plicated animals in many more points probably than in the more fimple ones ; and finally, that as thefe new organized parts, or# rudiments of the embryon, acquire new appetencies, ami pro- duce or find molecules with new propenfities, many fecondary parts are afterwards fabricated. Thus it would appear, that all nature exifls in a ftate of per- petual improvement by laws impreffed on the atoms of matter by the great cause of causes ; and that the world may ftill be in its infancy, and continue to improve for ever and ever. 5. Concerning the fpontaneous production of inicrofcopic animalcules, I beg leave to repeat, firft, that I fuppole the fmalleft ones to be formed by the coalefcence or embrace of the animal fibrils, which poffefs appetencies, with the animal mole- cules, which poffefs correfpondent propenfities ; and that the animal fibrils and molecules are found in all vegetable and ani- mal matter, as its organization becomes decompofed ; if there exifts along with it fufheient moifture and proper warmth. Secondly, that this kind of fpontaneous reproduction refem- bles actual generation in its confiding of the coalefcence of an- imal fibrils with appetencies and animal molecules with corref- pondent propenfities, that in the former they meet each other in the folution of animal matter, as it decompofes by ftagna- tion j whereas in the latter thefe formative fibrils and molecules are fecreted bv different pdands from the blood of the parent. Thirdly, that the firft animalcules produce other ones by ac- tual generation, but without fexes, like the buds of trees, and that as many generations may occur in a day, perhaps in an hour, I conceive, that they may gradually acquire new organi- zations, and improve by addition of new parts, as of fins, mouth, interlines, and finally, perhaps, fexual organs of reproduction. Thus the feed of a tulip produces a fmall root the fize of a pea the firfl fummer, with a fummit like a blade of grafs ; this dies in autumn, having previoufly produced a fucceffor larger than itfelf, and with a ftronger leaf qr fummit ; in the autumn this likewife perifhes, and a third generation is produced, which is ftill larger and more perfect ; till the fifth generation from the feed 43 5 GENERATION. Sect. XXXIX. 12.1. feed becomes fc much more perfect as to produce fexual or- gans of reproduction, as the flower with its anthers and ftigma. This curious analogy is not only fupported by the feedling buds of trees, which fucceed each other for ten or twelve gen- erations, the parent buds dying in the autumn, before they be- come fufheiently perfect to form the fexual organs of reproduc- tion in their flowers, as occurs in apple-trees j but is alfo ob- fervable in a complete infect, as in the aphis, which continues to propagate for nine generations from the egg without fex ; and then becomes fo perfect as to form fexual organs, and to produce an oviparous progeny. Other infects, as the moths and butterflies, undergo a great change of form, before they acquire the property of fexual reproduction ; and probably in- numerable other kinds of infects are fubject to the fame law. This idea of the production and changes of form of microf- copic animalcules is countenanced by the fmaller kinds, never, I believe, having been feen in their egg or infant ftate ; and by feme of them being capable of being revived in a few hours by warmth and moifture after having been dry and motionlefs for months, as the infect named vorticella. And laftly, from the changeful forms, which fome of them aflume, as that which is called proteus. See Baker and Adams on the Microfcope. Thus as by the attractions, and aptitudes to be attBHcted, which exift in inanimate matter, various new bodies are produced from the decompofition of thofe, which previoufly exifted ; fo by the appetencies to embrace, and the propenfities to be embraced, in animalized matter, various new animalcules are formed from the decompofition of thofe, which previoufly exifted ; owing in both cafes to the immutable laws imprefied both on inanimate and on organized matter by the great first cause. XII. 1. Cause and effect may be confidered as the progref- fion, or fucceilive motions, of the parts of the great fyftem of Nature. The ftate of things at this moment is the effect of the ftate of things, which exifted in the preceding moment ; and the caufe of the ftate of things, which {hall exift in the next moment. Thefe caufes and effects may be more eafily comprehended, if motion be confidered as a change of the figure of a group of bodies, as propofed in Sect. XIV. 2. 2. inafmuch as our ideas of vifible or tangible objects are more diftinct, than our ab- ftracted ideas of their motions. Now the change of the con- figuration of the fyftem of nature at this moment muft be an effect of the preceding configuration, for a change of configur- ation cannot exift without a previous configuration ; and the proximate caufe of every effect muft immediately precede that effect. Sect. XXXIX. 12. 2. GENERATION. 439 effect. For example, a moving ivory ball could not proceed onwards, unlefs it had previoufly begun to proceed ; or unlefs an impulfe had been previoufly given it ; which previous motion or impulfe conftitutos a part of the laft fituation of things. As the effects produced in this moment of time become caufes in the next, we may confider the progreffive motions of objects as a chain of caufes only ; whofe firft link proceeded from the great Creator, and which have exifted from the begin- ning of the created univerfe, and are perpetually proceeding. 2. Thefe caufes may be conveniently divided into two kinds, efficient and inert caufes, according with the two kinds of enti- ty fuppofed to exifl in the natural world, which may be termed matter and fpirit, as propofed in Sect. I. and further treated of in Seel:. XIV. The efficient caufes of motion, or new configura- tion, confift either of the principle of general gravitation, which actuates the fun and planets ; or of the principle of particular gravitation, as in electricity, magnetifm, heat j or of the princi- ple of chemical affinity, as in combuftion, fermentation, combi- nation ; or of the principle of organic life, as in the contraction of vegetable and animal fibres. The inert caufes of motion, or new configuration, confift of the parts of matter, which are in- troduced within the fpheres of activity of the principles above defcribed. Thus, when an apple falls on the ground, the prin- ciple of gravitation is the efficient caufe, and the matter of the apple-tree the inert caufe. If a bar of iron be approximated to a magnet, it may be termed the inert caufe of the motion, which brings thefe two bodies into contact ; while the magnetic principle may be termed the efficient caufe. In the fame man- ner the fibres, which conftitute the retina, may be called the in- ert caufe of the motions of that organ in vifion, while the fen- forial power may be termed the efficient caufe. 3. Another more common diftribution of the perpetual chain of caufes and effects, which conftitute the motions, or chang- ing configurations, of the natural world, is into active and paf- five. Thus, if a ball in motion impinges againft another ball at reft, and communicates its motion to it, the former ball is faid to act, and the latter to be acted upon. In this fenfe of the words a magnet is faid to attract iron ; and the prick of a fpur to ftimulate a horfe into exertion ; fo that in this view of the works of nature all things may be faid either fimply to exift, or to exift as caufes, or to exift as effects 5 that is, to exift either in an active or pa (live ftate. This distribution of objects and their motions, or changes of pofition, has been found fo convenient for the purpofes of common life, that on this foundation refts the whole conftruc- m 440 GENERATION. Sect. XXXIX. 12. 4, tion or theory of language. The names of the things them- felves are termed by grammarians Nouns, and their modes of exigence are termed Verbs. The nouns are divided into fub- ftantives, which denote the principal things fpoken of ; and in- to adjectives, which denote fome circumftances, or lefs kinds of things, belonging to the former. The verbs are divided into three kinds, fuch as denote the exigence of things fimply, as, to be ; or their existence in an active date, as, to eat ; or their ex- igence in a pafLve (late, as, to be eaten. Whence it appears, that all languages confut only of nouns and verbs, with their abbreviations for the greater expedition of communicating our thoughts ; as explained in the ingenious work of Mr. Home Tooke, who has unfolded by a fmgle flaih of light the whole theory of language, which had ib long lain buried beneath the learned lumber of the fchools. Diversions of Purley. Johnfon. London. 4. A third divifion of caufes has been into proximate and re- mote ; thefe have been much fpoken of by the writers on med- ical fubjecls, but without fulhcient precifion. If to proximate and remote caufes we add proximate and remote effects, we fhall include four links of the perpetual chain of caufation ; which will be more convenient for the difcuffion of many phi- lofophical fubjects. Thus if a particle of chyle be applied to the mouth of a Iac- I veflel, it may be termed the remote caufe of the motions of the fibres, which compofe the mouth of that lacteal veffel ; the fenforial power is the proximate caufe ; the contraction of the fibres of the mouth of the veflel is the proximate effecT: ; and their embracing the particle of chyle is the remote effecl; ; and theft four links of cauiation conititute abibrption. Thus when we attend to the rifmgfun, firit the yellow rays of light ftimuiate the fenforial power refiding in the extremities of the optic nerve, this is the remote caufe. 2. The fenforial power is excited into a ftate of activity, this is the proximate caufe. 3. The fibrous extremities of the optic nerve are con- tra-; led, this is the proximate effect. 4. A pleafurable or pain- ful fenfation is produced in confequence of the contraction of thefe fibres of the optic nerve, this is the remote effecl ; and thefe four links of the chain of caufation conititute the fenfi- tive idea, or what is commonly termed the fenfation of the ri- fing w.n. 5. Other caufes have been announced by medical writers un- der the nan t 5 of caufa procatar&ica, and caufa proegumina, and ine qua npn. All which are links more or lefs dif- tant • of remote caufes. To Sect. XXXIX. 12.6. GENERATION, 44 1 To thefe mufl: be added the final caufe, fo called by many au- thors, which means the motive, for the accomplifhment of which the preceding chain of caufes was put into action. The idea of a final caufe, therefore, includes that of a rational mind> which employs means to effect its purpofes ; thus the defire of preferving himfelf from the pain of cold, which he has frequent- ly experienced, induces the favage to conftruct his hut ; the fix- ing {takes into the ground for walls, branches of trees for rafters, and turf for a cover, are a feries of fucceffive voluntary exer- tions ; which are fo many means to produce a certain effect. This effect of preferving himfelf from cold, is termed the final caufe •, the conftruction of the hut is the remote effecl: •, the ac- tion of the mufcular fibres of the man, is the proximate effect ; the volition, or activity of defire to preferve himfelf from cold, is the proximate caufe ; and the pain of cold, which excited that defire, is the remote caufe. 6. This perpetual chain of caufes and effects, the firft link of which is rivetted to the throne of God, divides itfelf into innu- merable diverging branches, which, like the nerves arifing from the brain, permeate the mod minute and mod remote extremi- ties of the fyftem, diffufmg motion and fenfation to the whole. As every caufe is fuperior in power to the effect., which it has produced, fo our idea of the power of the Almighty Creator becomes more elevated and fublime, as we trace the opera- tions of nature from caufe to caufe, climbing up the links of thefe chains of being, till we afcend to the Great Source of ail things. Hence the modern difcoveries in chemiftry and in geology, by having traced the caufes of the combinations of bodies to remoter origins, as well as thofe in aftronomy, which digni- fy the prefent age, contribute to enlarge and amplify our ideas of the power of the Great Firft Caufe. And had thofe ancient philofophers, who contended that the world was formed from atoms, afcribed their combinations to certain immutable prop- erties received from the hand of the Creator, fuch as general gravitation, chemical affinity, or animal appetency, inltead of afcribing them to a blind chance ; the doctrine of atoms, as con- ftituting or compofing the material world by the variety of their combinations, fo far from leading the mind to atheiim, would strengthen the demonitration of the exiftence of a Deity, as the firft caufe of all things ■-, becaufe the analogy reflating irom our perpetual experience of cauie and effect would have thus been exemplified through univerla! nature. The heavens declare the Glory of God, and the firmament Jheiveth his handiwork I One dayttlleth cuiciher, and cm night Vol-. I. I 1 i c&t$etb 442 GENERATION. Sect. XXXIX. 1 2. S. cert'ifieth another ; they have neither fpeech nor language, yet their voice is gone forth into^all lands, and their words into the ends of the world. Manifold are thy works, O Lord ! in wifdom hajl thou made them all. Pfal. xix. civ. SECT. Sect. XL. OCULAR SPECTRA, 44* SECT. XL. On the Ocular Spectra of Light and Colours, by Dr. R. W. Darwin, of Shrewfbury. Reprinted, by permiflion, from the Philofophical Tranfactions, Vol. LXXVI. p. 313. Spectra of four kinds. 1. Activity of the retina in vifion. 2. Spec- tra from defect of fenftbility. 3. Spectra from excefs of fenfibili- ty. 4. Of direct ocular fpectra. 5. Greater fiimulus excites the retina into fpafmodic action. 6. Of reverfe ocular fpectra. 7. Greater flimulus excites the retina into various fuccejfve fpaf- modic actions. 8. Into fixed fpafmodic action. 9. Into tempora- ry paralyfts. I o. JMifcellaneous remarks ; 1 . Direct and re- verfe fpectra at the fame time. A fpectral halo. Rule to prede- termine the colours of fpectra. 2. Variation of fpectra from ex- traneous light. 3. Variation of fpectra in number, figure, and remiffion. 4. Circulation of the blood in the eye is vifibie. 5. A new way of magnifying objects. Conclufion. When any one has long and attentively looked at a bright object, as at the fetting fun, on clofing his eyes, or removing them, an image, which refembles in form the object he was at- tending to, continues fome time to be vifibie ; this appearance in the eye we (hall call the ocular fpectrum of that object. Thefe ocular fpectra are of four kinds : ift, Such as are owing to a lefs fenfibility of a defined part of the retina ; or fpectra from defect of fenfibility. 2d, Such as are owing to a greater fenfibility of a defined part of the retina \ ox fpectra from excefs of fenfibility. 3d, Such as refemble their object in its colour as well as form ; which may be termed direct ocular fpec- tra. 4th, Such as are of a colour contrary to that of their object ; which may be termed reverfe ocular fpectra. The laws of light have been moil fuccefsfully explained by the great Newton, and the perception of vifibie objects has been ably inveftigated by the ingenious Dr. Berkeley and M. Male- branche ; but thefe minute phenomena of vifion have yet been thought reducible to no theory, though many philolbphers have employed a confiderable degree of attention upon them : among thefe are Dr. Jurin, at the end of Dr. Smith's Optics ; M. iEpinus, in the Nov. Com. Petropol. V. 10.; M. Beguelin, in the Berlin Memoires, V. II. 1771 ; M. d'Arcy, in the Hiitoire de l'Acad. des Scienc. 1765 •, M. de la Hire; and, laftly, the celebrated M. de BufFon, in the Memoires de l'Acad. des Scien. who 444 OCULAR SPECTRA. Sect. XL. i. i, who has termed them accidental colours, as if fubjedted to no eftablifhed laws, Ac. Par. 1743. M. p. 215. I muft here apprize the reader, that it is very difficult for dif- ferent people to give the fame names to various (hades of colours ; whence, in the following pages, fomething muft be allowed, if on repeating the experiments the colours here mentioned fhould not accurately correfpond with his own names of them. I. Affivity of the Retina in Vifion. From the fubfequent experiments it appears, that the retina is in an atlive not in a paflive ftate during the exiftence of theie ocular fpe£tra ; and it is thence to be concluded, that all vifion is owing to the activity of this organ. 1. Place a piece of red filk, about an inch in diameter, as in plate 1, at Seel. III. 1, on a fheet of white paper, in a ftrong light ; look fteadily upon it from about the diftance of half a yard for a minute ; then clofmg your eyelids cover them with your hands, and a green fpeclrum will be feen in your eyes, re- iembling in form the piece of red filk : after fome time, thi3 ipeCtrum will difappear and (hortly reappear ; and this alter- nately three or four times, if the experiment is well made, till at length it vaniflies entirely. 2. Place on a fheet of white paper a circular piece of blue filk, about four inches in diameter, in the funffiine ; cover the centre of this with a circular piece of yellow filk, about three inches in diameter ; and the centre of the yellow filk with a cir- cle of pink filk, about two inches in diameter ; and the centre of the pink filk with a circle of green filk, about one inch in diameter ; and the centre of this with a circle of indigo, about half an inch in diameter ; make a fmall fpeck with ink in the very centre of the whole, as in plate 3, at Se&. III. 3. 6. ; look iteadily for a minute on this central fpot, and then ciofmg your eves, and applying your hand at about an inch diftance before them, fo as to prevent too much or too little light from paffing through the eyelids, you will fee the mod beautiful circles of colours that imagination can conceive, which are mod refemblcd bv the colours occasioned by pouring a drop or two of oil on a ilill lake in a bright day ; but theie circular iriies of colours are not only different from the colours of the filks above mention- ed, but are at the fame time perpetually changing as long as they exift. 3. When any one !n the dark prefles either corner of his eye with his finger, and turns his eye away from his finger, he will fee a circle cf colours like thofe in a peacock's tail : and a fudden Sect, XL. i. 4, OCULAR SPECTRA. 445 fudden fiafh of light is excited in the eye by a ftroke on it. (Newton's Opt, Q^i6.) 4. When any one turns round rapidly on one foot, till he becomes dizzy, and falls upon the ground, the fpeclra of the ambient objects continue to prefent themielves in rotation, or appear to librate, and he feems to behold them for fome time ft ill in motion. From all thefe experiments it appears, that the fpeclra in the eye are not owing to the mechanical impulfe of light imprefTed on the retina, nor to its chemical combination with that organ, nor to the abforption and emiilion of light, as is obferved in many bodies ; for in all thefe cafes the fpeotra muft either re- main uniformly, or gradually diminim ; and neither their alter- nate prefence and evanefcence as in the firft experiment, nor the perpetual changes of their colours as in the fecond, nor the flaih of light or colours in the prelTed eye as in the third, nor the rotation or libration of the fpeclra as in the fourth, could exiifc. It is not abfurd to conceive, that the retina may be (limulated into motion, as well as the red and white mufcles which form our limbs and veffcls ; fince it confifts of fibres, like thofe,. inter- mixed with its medullary fubftance. To evince this ftruclure, the retina of an ox's eye was lufpended in a glafs of warm water, and forcibly torn in a few places ; the edges of thefe parts appeared jagged and hairy, and did not contract, and be- come fmooth like fimple mucus, when it is diilended till it breaks ; which {hews that it confifts of fibres : and its fibrous construction became {till more diftimft. to the fight, by adding fome cauftic alkali to the water, as the adhering mucus was firit eroded, and the hair-like fibres remained floating in the vcflel. Nor does the degree of tranfparency of the retina invalidate the evidence of its fibrous Structure, fince Leeuwenhoek has (hewn that the cryftalline humour itfelf confifts of fibres. (Arcana Natune, Vol. I. p. 70.) Hence it appears, that as the mufcles have larger fibres inter- mixed with a fmaller quantity of nervous medulla, the organ of vifion has a greater quantity of nervous medulla intermixed with fmaller fibres -, and it is probable that the locomotive mufcles, as well as the vafcular ones, of microfcopic animals have much greater tenuity than thefe of the retina. And befides the fimilar laws, which will be (hewn in this paper to govern alike the actions of the retina and of the muf- cles, there are many other analogies which exift between them. They are both originally excited into a&ion by irritations, both a£t, nearly in the fame quantity of time, are alike itrengrhened or fatigued by exertion, are alike painful if excited into action when 446 OCULAR SPECTRA. Sect. XL. 2. 1. when they are in an inflamed ftate, are alike liable to paralyfis, and to the torpor of old age. II. Of spectra from defect of sensibility. The retina is not fo eafily excited into action by lefs irritation after having been lately fubjetled to greater. 1 . When any one paffes from the bright day-light into a dark- ened room, the irifes of his eyes expand themlelves to their ut- rrtoft extent in a few feconds of time ; but it is very long before the optic nerve, after having been ftimulated by the greater light of the day, becomes fenfible of the lefs degree of it in the room ; and, if the room is not too obfeure, the irifes will again contract. therofJves in fome degree, as the fenfibility of the retina returns. 2. Place about half an inch fquare of white paper on a black hat, and looking fteadily on the centre of it for a minute, remove your eyes to a iheet of white paper ; and after a fecond or two a dark fquare will be feen on the white paper, which will con- tinue fome time. A fimilar dark fquare will be feen in the clofed eye, if light be admitted through the eyelids. So after looking at any luminous object, of a fmall fize, as at the fun, for a fhort time, fo as not much to fatigue the eyes, this part of the retina becomes lefs fenfible to fmaller quantities of light ; hence, when the eyes are turned on other lefs lumi- nous parts of the iky, a dark fpot is feen refembling the fhape of the fun, or other luminous object which we lad beheld. This is the fource of one kind of the dark-coloured mufca volitantes. If thiv> dark fpot lies above the centre of the eye, we turn our eyes that way, expecting to bring it into the centre of the eye, that we may view it more diitincfcly ; and in this cafe the dark fpectrum feems to move upwards. If the dark fpeclrum is found beneath the centre of the eye, we purfue it from the fame motive, and it feems to move downwards. This has given rife to various conjectures of fomething floating in the aqueous humours of thft ever; ; but whoever, in attending to thefe fpots, keeps his eyes unmoved by looking fteadily at the corner of a cloud, at the fame time that he obferves the dark fpectra, will be thor- oughly convinced, that they have no motion but what is given to them by the movement of our eyes in purfuit of them. Some- times the form of the fpectrum, when it has been received from a circular luminous body, will become oblong \ and fometimes it will be divided into two circular fpetlra, which is not owing to our changing the angle made by the two optic axifes, accord- ing to the cHtance of the clouds or other bodies to which the fpectrum Sect. XL. 2. 3. OCULAR SPECTRA. 447 fpectrum is fuppofed to be contiguous, but to other caufes men- tioned in No. X. 3. of this fe and hence the num- ber and ihape of thefe fpeclra of the fun will continually vary, as long as they exift. The caufe of fome being more vivid than others, is the unfteadinefs of the eye of the beholder, fo that fome parts of the retina have been longer expofed to the fun- beams. That fome parts of a complicated fpettrum fade and return before other parts of it, the following experiment evinces. Draw three concentric circles ; the external one an inch and a half in diameter, the middle one an inch, and the internal one half an inch ; colour the external and internal areas blue, and the remaining one yellow, as in Fig. 4. \ after having looked about a minute on the centre of thefe circles, in a bright light, the fpeclrum of the external area appears firft in the clofed eye, then the middle area, and laftly the central one ; and then the central one disappears, and the others in inverted order. If con- centric circles of more colours are added, it produces the beau- tiful ever changing fpe£!rum in Sccl. I. Exp. 2. From Sect. XL. 10.4. OCULAR SPECTRA. 463 From hence it would feem, that the centre of the eye produ- ces quicker remiffions of fpectra, owing perhaps to its greater fenfibility ; that is to its more energetic exertions. Thefe re- miflions of fpectra bear fome analogy to the tremors of the hands, and palpitations of the heart, of weak people : and per- haps a criterion of the ftrength of any mufcle or nerve may be taken from the time it can be continued in exertion. 4. Variation of fpeclra in refpeel to brilliancy ; the vifihUitj of the circulation of the blood in the eye. 1. The meridian or evening light makes a difference in the colours of fome fpeclra ; for as the fun defcends, the red rays, which are lefs refrangible by the convex atmofphere, abound in •great quantity. Whence the fpectrum of the light parts of a window at this time, or early in the morning, is red ; and be- comes blue either a little later or earlier ; and white in the me- ridian day ; and is alfo variable from the colour of the clouds or fky which are oppofed to the window. 2. All thefe experiments are liable to be confounded, if they are made too foon after each other, as the remaining fpectrum will mix with the new ones. This is a very troublefome cir- cumftance to painters, who are obliged to look long upon the fame colour ; and in particular to thofe whofe eyes, from natur- al debility, cannot long continue the fame kind of exertion. For the fame reafon, in making thefe experiments, the refult be- comes much varied if the eyes, after viewing any object, are re- moved on other objects for but an inftant of time, before we clofe them to view the fpectrum ; for the light from the object, of which we had only a tranfient view, in the very time of do- ling our eyes acts as a ftimulus on the fatigued retina ; and for a. time prevents the defired fpectrum from appearing, or mixes its own fpectrum with it. Whence, after the eyelids are clofed, either a dark field, or fome unexpected colours, are beheld for a few feconds, before the defired fpectrum becomes diitinCtlyvifible. 3. The length of time taken up in viewing an object, of which we are to obferve the fpectrum, makes a great difference in the appearance of the fpectrum, not only in its vivacity, but in its colour ; as the direct fpeftrum of the central object, or of the circumjacent ones, and alfo the reverfe fpeftra of both, with their various combinations, as well as the time of their duration in the eye, and of their remiiTions or alterations, depend upon the degree of fatigue the retina is fubjected to. The Chevalier d'Arcy conftru 3. 7* NUTRIENTIA. 1 a kind of gruel. And the roots of fern, and probably of very many other roots, as of grafs and of clover taken up in winter, might yield nourifhment either by boiling or baking, and fepa- rating the fibres from the pulp by beating them ; or by getting only the flarch from thofe, which poffefs art acrid mucilage, as the white briony. And the alburnum of perhaps all trees, and efpecially of thofe which bleed in fpring, might produce a fac- charine and mucilaginous liquor by boiling it in the winter or fpring. 7. However the arts of cookery and of grinding may in- creafe or facilitate the nourifhment of mankind, the great fource of it is from agriculture. In the favage date, where men live folely by hunting, I was informed by ; Dr. Franklin, that there was feldom more than one family exifted in a circle of five miles diameter j which in a ftate of pafturage would fupport fome hundred people, and in a ftate of agriculture many thoufands. The art of feeding mankind on fo fmall a grain as wheat, which feems to have been difcovered in Egypt by the immortal name of Ceres, fhewed greater ingenuity than feeding them with the large roots of potatoes, which feem to have been a difcovery of ill-fated Mexico. This greater production of food by agriculture than by paftur- age, fhews that a nation nourifhed by animal food will be lefs nu- merous than if nourifhed by vegetable *, and the former will there- fore be liable, if they are engaged in war, to be conquered by the latter, as Abel was flain by Cain. This is perhaps the only valid argument againft inclofing open arable fields. The great production of human nourifhment by agriculture and pafturage evinces the advantage of fociety over the favage ftate ; as the number of mankind becomes increafed a thoufand fold by the arts of agriculture and pafturage ; and their happinefs is proba- bly under good governments improved in as great a proportion, as they become liberated from the hourly fear of beafts of prey, from the daily fear of famine, and of the occafional incurfions of their cannibal neighbours. But pafturage cannot exift without property both in the foil, and the herds which it nurtures ; and for the invention of arts, and production of tools necefTary to agriculture, fome muft think, and others labour ; and as the efforts of lbme will be crowned with greater fuccefs than that of others, an inequality of the ranks of fociety muft fucceed ; but this inequality of mankind in the prefent ftate of the world is too great for the purpofes of pro- ducing the greateft quantity of human nourifhment, mid the greateft fum of human happinefs ; there fhould be no flavery at c*ne end of the chain of fociety, and no defpotifm at the other. — By i4 NUTRIENTIA. Art. I. 2. 4, 1. By the future improvements of human reafon fuch govern- ments may poflibly hereafter be eftablilhed, as may a hundred- fold increafe the numbers of mankind/and a thoufand-fold their happinefs. IV. 1. Water muft be confidered as a part of our nutriment, becaufe fo much of it enters the compofition of our folids at well as of our fluids ; and becaufe vegetables are now believed to draw almoft the whole of their nouriihment from this fource. As in them the water is decompofed, as it is perfpired bv them in the funihine, the oxygen gas increafes the quantity and the purity of the atmofphere in their vicinity, and the hydrogen feems to be retained, and to form the nutritive juices, and cou- fcquent fecretions of refin, gum, wax, honey, oil, and other vcg- eruble productions. See Botanic Garden, Part I. Cant. IV. line 25, note. It has however other ufes in the fyftem, befides that of a nourifhing material, as it dilutes our fluids, and lubri- c ttes our folids ; and on all thefe accounts a daily fupply of it is required. 2. River-water is in general purer than fpring-watcr ; as the neutral falts warned down from the earth decompofe each other, except perhaps the marine fait ; and the earths, with which fpring-water frequently abounds, is precipitated ; yet it is not improbable, that the calcareous earth dilTolved in the water of many fprings may contribute to our ncurifhment, as the water from fprings, which contain earth, is faid to conduce to enrich thole lands, which are flooded with it, more than river water. The Chinefe are faid, by Sir G. Staunton, to purify the water cf fome muddy rivers or canals, by ftirring them with a hollow cane full of fmall holes, in the tube of which are enclofed fome pieces of alum. And the bakers in London afot, that one ufe of alum is to clear the New River water, and thus to render :ir bread whiter. Where any volatile alkali is mixed with water, as often happens from the liable dung and other ordure of populous towns, it will be converted to vitriolic ammoniac by a folution of alum : and calcareous earth mav be converted into gypfum, and fubfide along with the earth of the alum. See Clafs II. 1. 6. 16. * 3. Many arguments feem to fhew, that calcareous earth con- tributes to the nouriihment of animals and vegetables. Firft becaufe calcareous earth conftitutes a confiderable part of them, and muft therefore either be received from without, or formed by them, cr both, as milk, when taken as food by a laclefcent woman, is decompofed in the (lomach by the procefs of digef- tion, and again in part converted into milk by the pectoral glanc Secondly, becaufe from the analogy of all organic life, whatever ha Art. i a. 4. 3 » NUTRIENTI A, 15 has compofed a part of a vegetable or animal may again after Its chemical folution become a part of another vegetable or an- imal, fuch is the general transmigration of matter. And thirdly, becaufe the great ufe of lime in agriculture or* almoft all kinds of foil and fituation cannot be Satisfactorily explained from its chemical properties alone. Though thefe may alfo in cetrairi foils and fituations have confiderable effect. The chemical ufes of lime in agriculture may be, 1 . from its deftroying in a fhort time the cohefion of dead vegetable fibres, and thus reducing them to earth, which otherwife is effected by a flow procefs either by the confumpcion of infects or by a gradual putrefaction. Thus I am informed that a mixture o>: lime with oak bark, after the tanner has extracted from it what- ever is foluble in water, will in two or three months reduce it to a fine black earth, which, if only laid in heaps, it would re- quire as many years to effect by its own fpontaneous fermenta- tion or putrefaction. This effect; of lime muft be particularly ad- vantageous to newly enclofed commons when firft broken up. Secondly, lime for many months continues to attract moifture from the air or earth, which it deprives I fuppofe of carbonic acid, and then fuffers it to exhale again, as is feen on the plas- tered walls of new houfes. ( On this account it muft be advan- tageous when mixed with dry or fandy foils, as it attracts moif- ture from the air above or the earth beneath, and this moifture is then abforbed by the lymphatics of the roots of vegetables. Thirdly, by mixing lime with clays it is believed to .make them lefs cohefive, and thus to admit of their being more eafily pen- etrated by vegetable fibres. A mixture of lime with clays de- itroys their fuperabundancy of acid, if fuch exifts, and by unit- ing with it converts it into gypfum or alabafter. And Iaft.lv, frefh lime deftroys worms, fnails, and other infects, with which. it happens to Come in contaft. Yet do not all thefe chemical properties feem to account for the great ufes of lime in almoft all foils and fituations, as it con- tributes fo much to the melioration of the crops, as well as to their increafe and quantity. Wheat from land well limed is believed by farmers, millers, and bakers, to be, as they fuppofe, thinner fkinned ; that is, it turns out more and better flour ; which I fuppofe is owing to its containing more ftarch and lefs mucilage. In refpect to grafs-ground I am informed, that if a fpadeful of lime be thrown on a tufTock, which horfes or cattle have refufed to touch for years, they wiii for many fuc- ceeding feafons eat it quite clofe to the ground. One property of lime is not perhaps yet well underftood, I mean its producing fo much heat, when it is mixed with water i Vol. J, O o o w) 1 6 NUTRIENTIA. Art. I. 2. 4. 4. ■winch may be owing to the elementary fluid of heat confolidated in the lime. It is the (learn occafioned by this heat, when water is fprihkled upon lime, if the water be not in too gr^eat quan- tity or too cold, which breaks the lime into fuch fine powder as almoft to become fluid, which cannot be efFe&ed perhaps by any other means, and which I fuppofe mud give great prefer- ence to lime in agriculture, and to the folutions of calcareous earth in water, over chalk or powdered lime-ftone, when fpread upon the land. 4. It was formerly believed that waters replete with calcare- ous earth, fuch as incruft the infide of tea-kettles, or are faid to petrify mofs, were liable to produce or to increafe the (lone in the bladder. This miftaken idea has lately been exploded by the improved chemiftry, as no calcareous earth, or a very minute quantity, was found in the calculi analyfed by Scheele and Berg- man. The waters of Matlock and of Carlfbad, both which cover the mofs, which they pafs through, with a calcareous crufl, are fo far from increasing the ftone of the bladder or kidneys, that thofe of Carllbad are celebrated for giving relief to thofe labour- ing under thefe difeafes. Philof. Tranf. Thofe of Matlock are drunk in great quantities without any fufpicion of injury ; and I well know a perfon who for above ten years has drunk about two pints a day of cold water from a fpring, which very much incrufts the vellels, it is boiled in, with calcareous earth, and affords a copious calcareous fediment with a folution of fait of tartar, and who enjoys a ftate of uninterrupted health. V. 1. As animal bodies confift much both of oxygen and azote, which make up the compofition of atmofpheric air, thefe fhould be counted amongft nutritious fubftances. Befides that by the experiments of Dr. Prieftley it appears, that the oxygen gains admittance into the blood through the moift membranes of the lungs ; and feems to be of much more immediate confe- quence to the prefervation of our lives than the other kinds of nutriment above fpecified. As the ban's of fixed air, or carbonic acid gas, is carbone, which aifo conftitutes a great part both of vegetable and animal bodies ; this air fhould likewife be reckoned amongft nutritive fubftances. Add to this, that when this carbonic acid air is fwallowed, as it efcapes from beer or cyder, or when water is charged with it as detruded from limeftone by vitriolic acid, it affords an agreeable fenfation both to the palate and ftomach, and is therefore probably nutritive. The immenfe quantity of carbone and of oxygen which con- ftitutC i'o great a part of the limeftone countries is almoft be- yond conception, and, as it has been formed by animals, may again Art. 1. 1.6.1. NUTRIENTIA. T 7 again become a part of them, as well as the calcareous matter with which they are united. Whence it may be conceived, that the waters, which abound with limeflone in folution, may fupply nutriment both to animals and to vegetables, as mention- ed above. VI. i. The manner, in which nutritious particles are fub- ftituted in the place of thofe, which are mechanically abraded, or chemically decompofed, or which vaniih by animal abforp- tion, muft be owing to animal appetency, as defcribed in Sect, XXXVII. 3. and is probably fimilar to the procefs of inflamma- tion, which produces new veffels and new fluids ; or to that which conflitutes the growth of the body to maturity. Thus the granulations of new fleiTi to repair the injuries of wounds are vifible to the eye ; as well as the caucus matter, which ce- ments broken bones > the calcareous matter, which repairs in- jured fnail-fhells ; and the threads, which are formed by filk- worms and fpiders ; which are all fecreted in a fofter ftate, and harden by exficcation, or by the contact of the air, or by abforp- tion of their more fluid parts. "Whether the materials, which thus fupply the wafte of the fyftem, can be given any other way than by the flomach, fo as to preferve the body for a length of time, is worth our inquiry ; as cafes fometimes occur, in which food cannot be introduced into the ftomach, as in obftrucYions of the eefophagus, inflam- mations of the throat, or in hydrophobia ; Aid other cafes are not unfrequent in which the power of digeftion is nearly or to- tally deftroyed, as in anorexia epileptica, and in many ferers. In the former of thefe circum (lances liquid nutriment may fometimes be gotten into the ftomach through a flexible cathe- ter ; as defcribed in Clafs III. 1. 1. 15. In the latter many kinds of mild aliment, as milk or broth, have frequently been injected as clyfters, together with a fmall quantity of opium, as ten drops of the tincture, three or four times a day ; to which alfo might be added very fmall quantities of vinous fpirit. But thefe, as far as I have obferved, will nor long fuftain a perfon, who cannot take any fuftenance by the ftomach. 2. -Another mode of applying nutritive fluids might be by extend ve fomentations, or by im merging the whole body in a bath of broth, or of warm milk, which might at the fame tin be coagulated by rennet, or the acid of the calf's ftomach ; broth or whey might thus probably be introduced, in part at leaft, into the circulation, as a folution of nitre is faid to have been ab- sorbed in a pediluvium, which was afterwards difcovered Ivy the manner in which paper dipped frequently in the urine of the pa- tient and dried, burnt and fparkled like touch-rllper. Great quantity IS NUTRIENT1A, Art. 1. 2. 6. 3, quantity of water is alio known to be abforbed by thofe, who have bathed in the warm bath after exercife and abftinence from liquids. Cleopatra was faid to travel with 4000 milch-afles in her train, and to bathe every morning in their milk, which fiie probably might ufe as a cofmetic rather than a nutritive. 3. The transfufion of blood from another animal into the vein of one, who could take no fuftenance by the throat, or dU geft none by the ftomach, might long continue to fupport him > and perhaps ether nutriment, as milk or mucilage, might be this way introduced into the fyflem, but we have not yet fufficient experiments on this fubjec"t. See Sect. XXXII. 4. and Clafs I. 2, 3. 25. and Sup- I. 14. 2. VII. Various kinds of condiments, or fauces, have been tak- en along with vegetable or animal food, and have been thought by fome to ftrengthen the procefs of digeition and confequent pjocefs of nutrition. Of thefe wine, or other fermented liquors, vinegar, fait, fpices, and muftard, have been in mofl common nfe, and I believe to the injury of thoufands. As the ftomach by their violent (timulus at length lofes its natural degree of ir» ratability, and indigeftion is the confequence ; which is attend- ed with flatulency and emaciation. Where any of thefe have b.een taken fo long as to induce a habit, they muft either be continued, but not increafed *, or the ufe of them fhould be gradually and cautiouily diminifhed or difcontinued, as directed in Sed. XII. 7. 8, III. Catalogue of the Nutrientia, I. i. Venifon, beef, mutton, hare, goofe, duck, woodcock* fnipe, moor-game. Gyfters, lobfters, crabs, fhrimps, mufhrooms, eel, tench, barbolt, fmelt, turbot, fole, turtle. 3. Lamb, veal, fucking-pig. 4. Turkey, partridge, pheafant, fowl, eggs. 5. Pike, perch , gudgeon, trout, grayling. II. Milk, cream, butter, buttermilk, whey, cheefe. ill. Wheat, barley, oats, peafe, potatoes, turnips, carrots, cab- bage, afparagus, artichoke, fpinach, beet, apple, pear,, plum, apricot, nectarine, peach, flrawberry, grape, or- ange, melon, cucumber, dried figs, raifins, fugar, honey. With a great variety of other roots3 feeds, leaves, and fruits. ". Wateiyniver- water, fpring-water, calcareous earth. v, a Art. II. i. i. i. INCITANTIA. 19 V. Air, oxygene, azote, carbonic acid gas. VI. Nutritive baths and clyfters, transfuilon of blood. VII. Condiments. Art. II. INCITANTIA, 1. i. Those things, which increafe the exertions of all the irritative motions, are termed incitantia. As alcohol, or the fpirituous part of fermented liquors, opium, and many drugs, which are ftill efteemed poifons, their proper dofes not being afcertained. To thefe mould be added the exhilarating paflions of the mind, as joy, love : and externally the applica- tion of heat, electricity, ether, eiTential oils, frifUon, and ex- ercife. 2. Thefe promote both the fecretions and abforptions, in- creafe the natural heat, and remove thofe pains, which origin- ate from the defect of irritative motions, termed nervous pains ; and prevent the convulfions confequent to them. When given internally they induce coftivenefs, and deep coloured urine j and by a greater dofe intoxication, and its confequences. II. Observations on the Incitantia. 1. 1, Opium and alcohol increafe all the iecretions and ab- forptions. The increafe of the fecretion of fenforial power ap- pears from the violent exertions of drunken people ; the fecre- tion of fweat is more certainly excited by opium or wine than by any other medicine j and the increafe of general heat, which thefe drugs produce, is an evidence of their effect in promoting all the fecretions ; fince an increafe of fecretion is always at- tended with increafe of heat in the part, as in hepatic and other inflammations. 2. But as they at the fame time promote abforption ; thofe fluids, which are fecreted into receptacles, as the urine, bile, in- teftinai and pulmonary mucus, have again their thinner parts abforbed; and hence, though the quantity of fecreted fluid was increafed, yet as the abforption was alfo increafed, the ex- cretion from thefe receptacles is lefTened ; at the fame time that It is deeper coloured or of thicker confidence, as the urine, al- vine 2© INCITANTIA. Art. II. 2. 1. 3. vine feces, and pulmonary mucus. Whereas the perfpiration being fecreted on the furface of the body is vifible in its increas- ed quantity, before it can be reabforbed ; whence arifes that erroneous opinion, that opium increafes the cutaneous fecretion, and lefTens all the others. 3. It mud however be noted, that after evacuations opium feems to promote the abforptions more than the fecretions ; if you except that of the fenforial power in the brain, which prob- ably fufFers no abforption. Hence its efficacy in reftraining haemorrhages, after the veflels are emptied, by promoting vinous abforption. 4. In ulcers the matter is thickened by the exhibition of opi- um from the increafed abforption of the thinner parts of it 5 but it is probable, that the whole fecretion, including the part which is abforbed, is increafed ; and hence new fibres are fe- creted along with the matter, and the ulcer fills with new gran- ulations of fiefh. But as no ulcer can heal, till it ceafes to dis- charge ; that is, till the. abforption becomes as great as the ex- cretion ; thofe* medicines, which promote abforption only, are more advantageous for the healing an ulcer after it is filled with new flefh ; as the Peruvian bark internally, with banda- ges and folutions of lead externally. 5. There are many pains which originate from a want of due motion in the part, as thofe occafioned by cold j and all thofe pains which are attended with cold extremities, and are gener- ally termed nervous. Thefe are relieved by whatever excites the part into its proper actions, and hence by opium and alco- hol ; which are the molt univevfai ftimulants we are acquaint- ed with. In thefe cafes the effect oi vr is produced, as foon as the body becomes generally warm *, and a degree of in- toxication or fleep follows the cefTation of the pain. Thefe nervous pains (as they are called) frequently return at certain periods of time, and are alfo frequently fucceeded by convuifions ; in thefe cafes if opium removes the pain, the con- vulfions do not come on. For this purpofe it is bell to exhibit it gradually, as a grain every hour, or half hour, till it intoxi- cates. Here it muft be noted, that a much lefs quantity will prevent the periods of thefe cold pains, than is ncceffary to re- lieve them after their accefs. As a grain and half of opium given an hour before the expected paroxyfm will prevent the cold fit of an intermittent fever, but will not foon remove it, when it is already formed. For in the former cafe the ufual or healthy aflbciationsor catenations of motion favour the effect of the medicine •, in the latter cafe thefe affociations or catena- tions Art. II. 2.1.6. INCIT ANTI A. 2 1 tions are difordered, or interrupted, and new ones are formed, which fo far counteract the effect of the medicine. When opium has been required in large dofes to eafe or pre- vent convulfions, fome have advifed the patient to omit the ufe of wine, as a greater quantity of opium might then be exhibit- ed ; and as opium feems to increafe abforption more, and fe- cretion lefs, than vinous fpirit 5 it may in fome cafes be ufeful to exchange one for the other j as in difeafes attended with too great evacuation, as diarrhoea, and dyfentery, opium may be preferable ; on the contrary in tetanus, or l©cked-jaw, where inflammation of the fyftem might be of fervice, wine may be preferable to opium *, fee Clafs III. 1. 1. 12. I have generally obferved, that a mixture of fpirit of wine and warm water, giv- en alternately with the dofes of opium, has fooneft and mod certainly produced that degree of intoxication, which was necef- fary to relieve the patient in the epilepfia dolorifica. The external application of opium may alfo be ufed with ad- vantage, and efpecially when the ftomach rejects its internal ufe \ for this purpofe I have directed the whole fpine of the back to be moiftened with tincture of opium with fuccefs in epileptic convulfions. And an extenfive friction with a liniment confid- ing of fix grains of opium, well triturated v/ith an ounce of hog's fat, has lately been faid to induce fleep in maniacal cafes, by Dr. L. Frank of Florence. Injections of a folution or tincture of opium into the rectum act on the general conftitution, but require about double the quantity for that purpofe as when taken into the ftomach. In- jections of a folution of opium into the urethra may be of fervice to relieve pain, or to produce the abforption of the new veffels produced by inflammation, after fufficient evacuations, as is feen when it is applied to an inflamed eye. Or laftly, to alleviate the pain from acrid difcharges by increafing their abforption, or the pain from torpor of the part, as in fome tooth-achs, by its external application. 6. There is likewife fome relief given"by cpium to inflamma- tory pains, or thofe from excefs of motion in the affected part j but with this difference, that this relief from the pains, and the fleep, which it occafions, do not occur till fome hours after the exhibition of the opium. This requires to be explained ; after the ftimulus of opium or of alcohol ceafes, as after common drunkennefs, a confequent torpor comes on j and the whole habit becomes lefs irritable by the natural ftimuii. Hence the head-achs, ficknefs, and languor, on the next day after intoxica- tion, with cold fkin, and general debility. Now in pains from excefs of motion, called inflammatory pains, when opium isgiv- U 1NCITANTIA. Art. fat. a. i. 7 en, the pain is not relieved, till the debility comes on after the ftimulus ceafes to act -, for then after the greater flimulusof t) opium has exhauftcd much of the fenforial power, the lefs ftim- ulus, which before caufed the pain, does not now excite the part into unnatural action. In thefe cafes the ftimulus of the opium firft increafes the pain; and it fome times happens, that fo great a torpor follows, as to produce the death or mortification of the affected part ; when* the danger of giving opium in inflammatory difeafes, efpeciallv in inflammation of the bowels ; but in general the pain returns with its former violence, when the torpor above mentioned ceafes. Hence thefe pains attended with inflammation are beft relieved by copious venefeetion, other evacuations, and the clafs of medicines called torpentia. 7. Thefe pains from excefs of motion are attended with in- creafed heat of the whole, or of the affected part, and a ftrong quick pulfe 5 the pains from defect of motion are attended with cold extremities, and a weak pulfe ; which is alfc generally more frequent than natural, but not always fo. 8. Opium and alcohol are the only two drugs, we are much acquainted with, which intoxicate ; and by this circumftance are eaflly diflinguifhed from the fecernentia and forbentia. Camphor, and cicuta, and nicotiana, are thought to induce a kind of intoxication *, and there are many other drugs of this clafs, whofe effects are lefs known, or their dofes not ascertain- ed *, as atropa belladonna, hyofcyamus, ftramonium, prunus laurocerafus, menifpermum, cynoglofium, fome fungi, and the water diftilled from black cherry-flones ; the laft of which was once much in ufe for the convulfions of children, and was faid to have good effect ; but is now improvidently left out of our pharmacopoeias. I have known one leaf of the laurocerafus, (hred and made into tea, given every morning for a week with no ill confequence to a weak hyfteric lady, but rather perhaps with advantage. It is probable, that other bitter kernels, as thofe of horfe-chef- nuts, and of acorns, sefculus hippocaftanum, and quercus robur, may poffefs fomewhat of an intoxicating quality } and by this kind of ftimulus, as well as by their bitter part, may be ufed to prevent the paroxyfm of an ague, if adminiftered an hour be- fore the expected accefs of it, as is lately afhrmed by Dr. Fuchs of Jena ; who fays, an extract prepared from the ripe kernels of the horfc-chefnut acts like an extract of Peruvian bark ; and Ids that the bark alfo of this tree is ufed with fuccefs inftead of the Peruvian bark. The pernicious effects of a continued ufe of much vinous fpirit Art, It. 2. i. 10. INCITANTIA, fpirit is daily feen and lamented by phyficians j not only early debility, like premature age, but a dreadful catalogue of difeafes is induced by this kind of intemperance ; as dropfy, gout, lep-> rofy, epilepfy, infanity, as defcribed in Botanic Garden, Part II. Canto III. line 357. The ftronger or lefs diluted the fpirit is taken, the fooner it feems to deftroy, as in dram-drinkers ; but ftill fooner, when kernels of apricots, or bitter almonds, or lau- rel-leaf, are infufed in the fpirit, which is termed ratafia j a3 then two poifons are fwallowed at the fame time. And vine- gar, as it contains much vinous fpirit, is probably a noxious part of our diet. And the di (tilled vinegar, which is commonly fold in the (hops, is truly poifonous, as it is generally dittilled by means of a pewter or leaden alembic-head or worm-tube, and abounds with lead j which any one may detect by mixing with it a folution of liver of fulphur. Opium, when taken as a lux- ury, not as a medicine, is as pernicious as alcohol ; as Baron de Tott relates in his account of the opium-eaters in Turkey. ,io. It muft be obferved, that a frequent repetition of the ufe of this clafs of medicines fo habituates the body to their ftimu- lus, that their dofe may gradually be increafed to an aftoniming quantity, fuch as otherwife woura inftantly deftroy life ; as is frequently feen in thofe, who accuftom themfelves to the daily ufe of alcohol and opium ; and it would feem, that thefe unfor* tunate people become difeafed as fcon as they omit their ufual. potations ; and that the confequent gout, dropfy, palfy, or pirn* pled face, occur from the debility occafioned from the want of accuftomed ftimuius, or to fome change in the contractile fi- bres, which requires the continuance or increafe of it. Whence the cautions neceflary to be obferved are mentioned in Sect* XII. 7. 8. . 11. It is probable, that fome of the articles in the fubfequent catalogue do not induce intoxication, though they have been efteemed to do fo ; as tobacco, hemlock, nux vomica, flavifa- gria ; and on this account mould rather belong to other arrange* ments, as to the fecernentia, or forbentia, or invertentia. II. 1. Externally the application of heat, as the warm bath, by its ftimulus on the fkin excites the excretory ducts of the perfpirative glands, and the mouths of the lymphatics, which open on its furface, into greater action ; and in confequen.ee many other irritative motions, which are afibciated with them. To this increafed action is added pleafurable fenfatlon, which adds further activity to the fyflem ; and thus many kinds of pain re- ceive relief from this additional atmofphere of heat. The ufe of a warm bath of about 96 or 98 degrees of heat, for half an hour once a day for three or four months, I have Vol. I. P p p known 24 INCITANTIA. Art. II. 2. 2. r. known of great fervice to weak people, and is perhaps the leaft noxious of all unnatural ftimuli ; which however, like all other great excitement, may be carried to excefs, as complained of by the ancients. The unmeaning application of the words relaxation and bracing to warm and cold baths has much prevented the ufe of this grateful ftimulus •, and the mifufe of the term warm- bath, when applied to baths colder than the body, as to thofe of Buxton and Matlock, and to artificial baths of lefs than 90 de- grees of heat, which ought to be termed cold ones, has contrib* utcd to miflead the unwary in their application. The ftimulus of wine, or fpice, or fait, increafes the heat of the fyftem by increafing all or fome of the fecretions ; and hence the ftrength is diminifhed afterwards by the lofs of fluids, as well as by the increafed action of the fibres. But the ftimulus of the warm-bath fupplies heat rather than produces it ; and rather fills the fyftem by increafed abforption, than empties it by increafed fecretion ; and may hence be employed with advan- tage in almoft all cafes of debility with cold extremities, perhaps even in anafarca, and at the approach of death in fevers. In thefe cafes a bath much beneath 98 degrees, as of 80 or 85, might do injury, as being a cold-bath compared with the heat of the body, though fuch a bath is generally called a warm one. The activity of the fyftem thus produced by a bath of 98 de- grees of heat, or upwards, does not feem to render the patients liable to take cold, when they come out of it ; for the fyftem is lefs inclined to become torpid than before, as the warmth thus acquired by communication, rather than by increafed action, continues long without any confequent chillnefs. Which ac- cords with the obfervation of Dr. Fordyce, mentioned in Sup. I. 5. 1. who fays, that thofe who are confined fome time in an atmcfphere of 120 or 130 degrees of heat, do not feel cold or look pale on coming into a temperature of 30 or 40 degrees; which would produce great palenefs and fenfation of coldnefs in thofe, who had been fome time confined in an atmofphere of only 86 or 90 degrees of heat. Treatife on Simple Fever, p. 168. Hence heat, where it can be confined on a torpid part along with moifture, as on a fcrofulous tumour, will contribute to produce fuppuration or refolution. This is done by applying a warm poultice, which iliould be frequently repeated ; or a plaf- fcer of refin, wax, or fat ; or by covering the part with oiled filk ; both which laft prevent the perfpirable matter from escap- ing as well as the heat of the part, as thefe fubftanccs repel moifture, and are bad conductors of heat. Another great ufe P»f the ftimulus of heat is by applying it to torpid ulcers, which arr Art. II. 2. 2. i. INCITANTIA. 25 are generally termed fcrofulous or fcorbutic, and are much eafier inclined to heal, when covered with feveral folds of flannel. Mr. had for many months been afflicted with an ulcer in perinseo, which communicated with the urethra, through which a part of his urine was daily evacuated with confiderable pain ; and was reduced to a great degree of debility. He ufed a hot-bath of 96 or 98 degrees of heat every day for half an hour during about fix months. By this agreeable (timulus re- peated thus at uniform times not only the ulcer healed, contra- ry to the expectation of his friends, but he acquired greater health and ftrength, than he had for fome years previouily ex- perienced. Mrs. was affected with tranfient pains, which were call- ed nervous fpafms, and with great fear of difeafes which (he did not labour under, with cold extremities, and general debil- ity. She ufed a hot-bath every other day of 96 degrees of heat for about four months, and recovered a good ftate of health, with greater ftrength and courage, than fee had poiTelJed for many months before. Mr. Z. a gentleman about 65 years of age, had lived rather intemperately in refpecl: to vinous potation, and had for many years had annual vifits of the gout, which now became irregu- lar, and he appeared to be lofing his ftrength, and beginning to feel the effects of age. He ufed a bath, as hot as was agreea.- ble to his fenfations, twice a week for about a year and half, and greatly recovered his health and ftrength with lefs frequent and lefs violent returns of regular gout, and is now near 8© years of age. When Dr. Franklin, the American philofopher, was in En- gland many years ago, I recommended to him the ufe of a warm-bath twice a week to prevent the too fpeedy accefs of old age, which he then thought that he felt the approach of, and I have been informed, that he continued the ufe of it till near his death, which was at an advanced age. All thefe patients were advifed not to keep themfelves warm- er than their ufual habits, after they came out of the bath, wheth- er they went into bed or not ; as the defign was not to promote perfpiration, which weakens all conftitutions, and feldom is of fervice to any. Thus a flannel fhirt, particularly if it be worn in warm weather, occafions weaknefs by ftimulating the fkiii by its points into too great action, and producing heat in confe- quence ; and occafions emaciation by incrcafing the difcharge of perfpirable matter ; and in both thefe refpecls differs from the effett of warm bathing, which communicates heat to the fvftcm INCITANTIA. A*t. II. 2. 2. 2. fyftem at the fame time that it ftimulates it, and caufes abforp- tion more than exhalation. Thoie who have remained half an hour in a warm bath, when they have previoufly been exhaufted by exercife, or abflinence from food or fluids, have abforbed fo much as to increafe their weight confiderably. Dr. Jurm found an increafe of weight to 1 8 ounces by lleeping in a cool room after a day's exercife and abftinence, fo much in that Situation was abforbed from the at- mofphere. But it has lately been obferved by Dr. Rollo and by Dr. Currie, that fome patients did not weigh heavier after com- ing out of the warm bath, and being wiped dry. From whence we may conclude, that ihefe patients were not previoufly in a ftate of inannition •, or that they had remained fo long in the bath as to lofe fomewhat by the perpetual wafte of the fyftem by digeftion, circulation, and fecretion. And certainly as no wafte occurs by the ufe of the warm bath, this mult be the molt harmlefs, confequently the mod falutary of all increafed ftimuli. See Clafs I. 1. 2. 3. 2. The effect of the paffage of an electric (hock through a paralytic limb in caufing it to contract, befides the late experi- ments of Galvani and Volta on frogs, entitle it to be clafled, ^ongft univerfal ftimulants. Electric (hocks frequently re- peated daily for a week or two remove chronical pains, as the pleurodyne chronica, Clafs I. 2. 4. 14. and other chronic pains, which are termed rheumatic, probably by promoting the abforp- tion of fome extravafated material. Scrofulous tumours are fometimes abforbed, and fometimes brought to fuppurate by pailing electric (hocks through them daily for two or three weeks. Mils -, a young lady about eight years of age, had a f welling about the fize of a pigeon's egg on her neck- a little below her ear, which long continued in an indolent (tate„ Thirty or forty fmall electric (hocks were parTed through it once or twice a day for two or three weeks, and it then fuppurated and healed without difficulty. For this operation the coated jar of the electric machine had on its top an electrometer, which meafured the ihocks by the approach of a brafs knob, which Communicated with the external coating to another, which communicated with the internal one, and their diftance was ad- justed by a fcrew. So that the (hocks were fo fmall as not to alarm tixe child, and the accumulated electricity was frequently discharged as the wheel continued turning. The tumour was cnclofed between two other brafs knobs, which were fixed on wires, which pafled through glafs tubes ; the tubes were cement* in two grooves on a board, fo that at one end they were nearer Art. II. 2. 3. 1. INCITANTIA. 27 nearer each other than at the other, and the knobs were pufhed out fo far as exactly to include the tumour. Inflammations of the eyes without fever are frequently cured by taking a ftream of very fmall electric fparks from them, or giving the electric fparks to them, once or twice a day for a week or two j that is, the new vefTels, which conftitute inflam- mation in thefe inirritable conftitutions, are abforbed by the ac- tivity of the abforbents induced by the ftimulus of the electric aura. For this operation the eafieft method is to fix a pointed wire to a ftick of fealing wax, or to an infulating handle of glafs ; one end of this wire communicates with the prime conductor, and, the point is approached near the inflamed eye in every di- rection. III. Externally the application of ether, and of effential oils, as of cloves or cinnamon, feems to pofTefs a general flimulating effect. As they inftantly relieve tooth-ach, and hiccough, when thefe pains are not in violent degree ; raid camphor in large dofes is faid to produce intoxication ; this effect however I have not been witnefs to, and have reafon to doubt. Ether dropped into the ears of fome deafifh people, feems to poiTefs a two-fold e^/Fect, one of diflblving the indurated ear-wax, and the other of flimulating the torpid organ, but it is liable to give fome degree of pain, unlets it be freed from the fulphurous acid, fome of which arifes along with it in diftillation ; to pu- rify it from this material it mould be rectified from manganefe. See Oafs I. 2. 5. 6. Lime added to impure ether may alfo unite with the fulphuric acid, if fuch exifts in it, and form fele- nite, and fubfide. The manner in which ether and the efTential oil operate on the fyflem when applied externally, is a curious queition, as pain is fo immediately relieved by them, that they mud fcem to penetrate by the great fluidity or expaniive property of a part of them, as of their odoriferous exhalation or vapour, and thus ftim~ ulate the torpid part, and not by their being taken up by the ab- ibrbent veflels, and carried thither by the long courfe of circula- tion •, nor is it probable, that thefe pains are relieved by the fympathy of the torpid membrane with the external fkin, which is thus Simulated into action •, as it does not fucceed, unlcfs it is applied over the pained part. Thus there appears to be three different modes by which extraneous bodies may be introduced into the fyftem, befides that of abforption. ift. By ethereal tranfuion, as heat and electricity ; 2d. by chemical attraction, as oxygen j and 3d. by expanfive vapour, as ether and efTen- tial oils. IV. The perpetual neceflity of the mixture of oxygen gas with .5 INCITANTIA. Art. II. 2. 4. 1. with the blood in the lungs evinces, that it mull act as a ftimu- lus to the fanguiferous fyftem, as the motions of the heart and arteries prefently ceafe, when animals are immerfed in airs which pofTefs no oxygen. It may alfo fubfequently anfwer another important purpofe, as it is probable that it affords the material for the production of the fenforial power ; which is fuppofcd to be lecreted in the brain or medullary part of the nerves ; and that the perpetual demand of this fluid in refpira- tion is occafioned by the fenforial power, which is fuppofed to be produced from it, being too fubtle to be long confined in any part of the fyftem. Another proof of the ftimulant quality of oxygen appears from the increafed acrimony, which the matter of a common abfcefs pofleffes, after it has been expofed to the air of the at- mofphere, but not before j and probably all other contagious matters owe their fever-producing property to having been con- verted into acids by their union with oxygen. See Clafs II. I. 8. As oxygen penetrates the fine moift membranes of the air-vef- fels of the lungs, and unites with the blood by a chemical at- traction, as is feen to happen, when blood is drawn into a bafon, the lower furface of the craffamentum is of a very dark red fo long as it is covered from the air by the upper furface, but be- comes florid in a fhort time on its being expofed to the atmof- phere ; the manner of its introduction into the fyftem is not probably by animal abforption but by chemical attraction, in which circumftance it differs from the fluids before mentioned both of heat and electricity, and of ether and effential oils. As oxygen has the property of palling through moift animal membranes, as firft difcovered by the great Dr. Prieftley, it is probable it might be of ufe in vibices, and petechia in fevers, and in other bruifes ; if the lkin over thofe parts was kept moift by warm water, and covered with oxygen gas by means of an inverted glafs, or even by expofing the parts thus moiftened to the atmofphere, as the dark coloured extravafated blood might thus become florid, and by its increafe of ftimulus facilitate its jreabforption. Two weak patients, to whom I gave oxygen gas in as pure a flate as it can eafily be produced from Exeter manganefe, and in the quantity of about four gallons a day, feemed to feel re- freshed, and ftronger, and to look better immediately after ref- piring it, and gained ftrength in a fhort time. Two others, one of whom laboured under confirmed hydrothorax, and the other under a permanent and uniform difficulty of refpiration, were not refrefhed, or in any way ferved by the ufe of oxygen in .he above quantity of four gallons a day for a fortnight, which Art. II. 2. 5. 1. INCITANTIA. 29 I afcribed to the inirritability of the difeafed lungs. For other cafes the reader is referred to the publications of Dr. Beddoes ; Confiderations on the Ufe of Factitious Airs, fold by Johnfon, London. Its effects would probably have been greater in refpect to the quantity breathed, if it had been given in a dilute ftate, mixed with 1 o or 20 times its quantity of atmofpheric air, as otherwife much of it returns by expiration without being deprived of its quality, as may be feen by the perfon breathing on the flame of a candle, which it enlarges. See the Treatife of Dr. Beddoes above mentioned. Mr. Scott in his letters in the Bombay Courier gave the black calciform ore of manganefe in the quantity, he fays, of feveral drachms a day without any inconvenience to a venereal patient, hoping to ferve him by the oxygen contained in that calx. I have formerly given lapis calaminaris to the quantity of 20 grains twice a day in confumption, without inconvenience, and I fuppofe this calciform ore of zinc, as well as the ruft of iron, may be an union of thofe metals with oxygen, and may probably be given internally with more fafety than calces of lead, which were once famous in confumptions. See Clafs II. 1. 5. 2. and Article IV. 2. 7. 1. V. Thofe paflions, which are attended with pleafurable fenfa* tion, excite the fyftem into increafed action in confequence of that fenfation, as joy, and love, as is feen by the flufh of the fkin. Thofe paffions, which are attended with difagreeable fenfation, produce torpor in general by the expenfe of fenforial power oc- cafioned by inactive pain ; unlefs volition be excited in confe- quence of the painful fenfation ; and in that cafe an increafed activity of the fyftem occurs j thus palenefs and coldnefs are the confequence of fear,but warmth and rednefs are the confequence of anger. > VI. Befides the exertions of the fyftem occafioned by increaf- ed ftimuli, and confequent irritation, and by the paffions of the mind above defcribed, the increafed actions occafioned by exer- cife belong to this article. Thefe may be divided into the ac- tions of the body in confequence of volition, which is generally termed labour ; or fecondly, in confequence of agreeable fenfa- tion, which is termed play or fport ; thirdly, the exercife occa- fioned by agitation, as in a carriage or on horfeback •, fourthly, that of friction, as with a brufh or hand, fo much ufed in the ©aths of Turkey ; and laftly, the exercife of fwinging. The firft of thefe modes of exercife is frequently carried to great excefs even amongft our own labourers, and more fo un- der the lafh of flavery ; fo that the body becomes emaciated and finks 3o INCITANTXA. Art. II. 2. &. u links under either the prefent hardfhips, Of by a premature old age. The fecond mode of exercife is Ktn in the play of all young animals, as kittens, and puppies, and children ; and is fo neceiiary to their healtk as well as to tiieir pleafure, that thofe children, which are too much confined from it, not only become pale-faced and bloated, with tumid bellies, and confequent worms, but are liable to get habits of unnatural actions, as twitching of their limbs, or feme parts of their countenance ; together with an ill-humoured or difcontented mind. Agitation in a carriage or on horfeback, as it requires fome little voluntary exertion to preferve the body perpendicular, but much lefs voluntary exertion than in walking, feems the bell: adapted to invalids ; who by thefe means obtain exercife prin- cipally by the ftrength of the horfe, and do not therefore too much exhauft their own fenibrial power. The ufe of friction with a bruQi or hand, for half an hour or longer morning and evening, is ft ill better adapted to thofe, who are reduced to ex- treme debility ; and none of their own fenforial power is thus expended, and affords fomewhat like the warm-bam activity without 'felf-exertion, and is ufed as a luxury after warm bathing in many parts of Afia. Another kind of exercife is that of fwinging, which requires fome exertion to keep the body perpendicular, or pointing to- wards the centre of the fwing, but is at the fame time attended with a degree of vertigo ; and is defcribed in Clafs II. 1. 6. 7. IV. 2. 1. 10. Sup. I. 3. and 15. The neceflity of much exercife has perhaps been more infilled upon by phyfician?, than nature feems to demand. Few ani- mals exercife themfelves fo as to induce viiible fweat, unlefs urg- ed to it by mankind, or by fear, or hunger. And numbers of people in our market towns, 'of ladies particularly, with fmall fortunes, live to old age in health, without any kind of exercife of bodv, or much activitv of mind. In fummer weak people cannot continue too long in;the air, if it can be done without fatigue ; and in winter they fhould go out feveral times in a day for a few minutes, ufing the cold air like a cold-bath, to invigorate and render them more hardy. III. Catalogue of the Incitantia. I. Papaver fomniferum ; poppy, opium. Alcohol, wine, beer, cyder. Prunus lauro-cerafus ; laurel, diftilled water from the leav Primus cerafus ; black cherry, diftilled water from 1 kernels. Nicotians Art. HI. i.i. SECERNENTI A, 3 s Nicotiana tabacum 5 tobacco ; the effential oil, decoction of the leaf. Atropa belladonna ; deadly nightmade, the berries. Datura ftramoneum ; thorn-apple, the fruit boiled in milk. Hyofcyamus reticulatus ; henbane, the feeds and leaves. CynoglofTum ; hounds tongue. Menifperftium, cocculus ; Indian berry. Amygdalus amarus 5 bitter almond. Cicuta j hemlock. Conium maculatum I Strychnos nux vomica ? Delphinium ftavifagria ? II. Externally, heat, electricity. III. Ether, elfential oils. IV. Oxygen gas. V. Paflions of love, joy, anger. VI. Labour, play, agitation, friction. Art. III. SECERNENTIA. I. Those things which increafe the irritative motions, which conflitute fecretion, are termed fecernentia ; which are as vari- ous as the glands, which they ftimulate into action; 1. Diaphoretics, as aromatic vegetables, efiential oils, ether, volatile alkali, neutral falts, antimonial preparations, external heat, exercife, friction, cold water for a time with fubfequent warmth, blifters, electric fluid. 2. Sialagogues, as mercury internally, and pyrethrum exter- nally. 3. Expectorants, as fquill, onions, gum ammoniac, feneka root, mucilage : fome of thefe increafe the pulmonary perfpira- tion, and perhaps the pulmonary mucus. 4. Diuretics, as neutral falts, fixed alkali, balfams, refins, af- paragus, cantharides. 5. Cathartics of the mild kind, as fenna, jalap, neutral falts, manna. They increafe the fecretions of bile, pancreatic juice, and inteftinal mucus. 6. The mucus of the bladder is increafed by cantharides, and perhaps by oil of turpentine. Vol, I. Qj^q > The 3z SECERNENTIA. Art. III. i. i. 7. 7. The mucus o£ the rectum by aloe internally, by clyfters and fuppofitories externally. 8. The mucus of the cellular membrane is increafed byblif- ters and finapifms. 9. The mucus of the noltrils is increafed by errhines of the milder kind, as marum, common fnuff. 1©. The fecretion of tears is increafed by volatile fairs, the vapour of onions, by grief, and joy. 11. All thofe medicines increafe the heat of the body, and remove thofe pains, which originate from a defect of motion in the veffels, which perform fecretion ; as pepper produces a glow on the fkin, and balfam of Peru is faid to relieve the flatulent colic. But thefe medicines differ from the preceding clafs, as they neither induce coftivenefs nor deep coloured urine in their ufual dofe, nor intoxication in any dofe. 1 2. Yet if any of thefe are ufed unneceffarily, it is obvious, like the incitantia, that they mult contribute to fhorten our lives by fooner rendering peculiar parts of the fyftem difobedient to their natural ftimuli. Of thofe in daily ufe the great excefs of common fait is probably the molt pernicious, as it enters all out- cookery, and is probably one caufe of fcrofula, and of fea-fcur- vy, when joined with other caufes of debility. See Botanic Garden, Part II. Canto IV. line 221. Spices taken to excefs by Simulating the ftomach, and the vefTels of the (kin by affoci- atipn, into unneceffary action, contribute to weaken thefe parts of the fyftem, but are probably lefs noxious than the general ufe of fo much fait. II. Observations on the Secernentia. I. 1 . Some of the medicines of this clafs produce abforption in fome degree, though their principal effect is exerted on the fecerning part of our fyftem. We fhall have occafion to ob- ferve a fimilar circumltance in the next clafs of medicines term- ed Sorbentia ; as of thefe fome exert their effects in a fmaller degree on the fecerning fyftem. Nor will this furprife any one, who has obferved, that all natural objects are prefented to us in a ftate of combination ; and that hence the materials, which produce thefe~different effects, are frequently found mingled in the fame vegetable. Thus the pure aromatic3 increafe the ac- tion of the veffels, which fecrete the perfpirable matter ; and the pure attringents increafe the action of the veffels, which ab- forb the mucus from the lungs, and other cavities of the body ; hence it mult happen, that nutmeg, which poffeffes both thefe qualities, fhould have the double effect above mentioned. Other Art. III. 2.1.2. SECERNENTI A. 3 3 Other drugs have this double effect, and belong either to the clafs of Secernentia or Sorbentia, according to the dole in which they are exhibited. Thus a fmall dofe of alum increafes ab- forption, and induces coftivenefs ; and a large one increafes the fecretions into the inteftinal canal, and becomes cathartic. And this accounts for the conftipation of the belly left after the pur- gative quality of rhubarb ceafes, for it increafes abforption in a fmaller dofe, and fecretion in a greater. Hence when a part of the larger dofe is carried out of the habit by (tools, the fmall quantity which remains induces coftivenefs. Hence rhubarb exhibited in fmall dofes, as two or three grains twice a day, ftrengthens the fyftem by increafing the action of the abforbent veffels, and of the inteftinal canal. 2. Diaphoretics. The perfpiration is a fecretion from the blood in its pafTage through the capillary veflels, as other fecre- tions are produced in the termination of the arteries in the va- rious glands. After this fecretion the blocd lofes its florid colour, which it regains in its pafTage through the lungs ; which evinces that fomething beiides water is fecreted on the Ikins of animals. No ftatical experiments can afcertain the quantity of our per- fpiration ; as a continued abforption of tfye moiiture of the at- mofphere exifts at the fame time both by the cutaneous and pul- monary lymphatic. 3. Every gland is capable of being excited into greater exer- tions by an appropriated ftimulus applied either by its mixture with the blood immediately to the fecerning veflel, or applied externally to its excretory duet. Thus mercury internally pro- motes an increafed falivation, and pyrethrum externally applied to the excretory ducts of the falival glands. Aloes itimulate the rectum internally mixed with the circulating blood ; and fea-falt by injection externally. Now as the capillaries, which fecrete the perfpirable matter, lie near the furface of the body, the application of external heat acts immediately on their excre- tory ducts, and promotes perfpiration ; internally thofe drugs which poffefs a fragrant effential oil, or fpiritus rector, produce this effect, as the aromatic vegetables, of which the number is very great. 4. It mult be remembered, that a due quantity of fome aqueous vehicle mud be given to fupport this evacuation ; oth- erwife a burning heat without much vifible fweat mult be the confequence. When the fkin acquires a degree of heat much above ie>8, as appears by Dr. Alexander's experiments, no viii- ble fweat is produced ; which is owing to the great heat of the ikin evaporating it as haftily, as it is fecreted -, and, where the fwe m I 34 SECERNENTIA. Art. III. 2. i. 5. fweat is fecreted in abundance, its evaporation cannot carry off the exuberant heat, like the vapour of boiling water •, becaufe a great part of it is wiped off, or abforbed by the bed-clothes ; or the air about the patient is not changed fufficiently often, as it becomes faturated with the perfpirable matter. And hence it is probable, that the wafle of perfpirable matter is as great, or greater, when the fkin is hot and dry, as when it (lands in drops on the fkin > as appears from the inextinguifhable third. Hence Dr. Alexander found, that when the heat of the body was greater than 108, nothing produced fweats but repeated draughts of cold water \ and of warm fluids, when the heat was much below that degree. And that cold water which pro- cured fweats inftantaneoufly when the heat was above- 1 08, flopped them as certainly when it was below that heat ; and that flannels, wrung out of warm water and wrapped round the legs and thighs, were then mofl certainly productive of fweats. 5. The diaphoretics are all faid to fucceed much better, if given early in the morning, about an hour before fun-rife, than at any other time ; which is owing to the great excitability of every part of the fyftem after the fenforial power has been accumu- lated during 'fleep. In thofe, who have hectic fever, or the fe- bricula, or nocturnal fever of debility, the morning fweats are owing to the decline of the fever-fit, as explained in Sect. XXXIL 9. In fome of thefe patients the fv^eat does not occur till they awake ; becaufe then the fyftem is ftill more excitable than du- ring fleep, becaufe the afliftance of the voluntary power in refpiration facilitates the general circuhtion. See Clafs L 2. I. 3. (:. It mufl be obferved, that the fkin is very dry and hard to the touch, where the abforbents, which open on its furface, do not act \ as in fome dropfies, and other diieafes attended with great third. This drynefs, and fhrivelled appearance, and rough- nefs, are owing to the mouths of the abforbents being empty of their accuftomed fluid, and is diftinguifhable from the drynefs of the fkin above mentioned in the hot fits of fever, by its not being attended with heat. As the heat of the ikin in the ufual temperature of the air always evinces an increafed perfpiration, whether vifible or not, rhe heat being produced along with the increafe of fecretion ; it follows, that a defect of perfpiration can only exift, when the fkin is cold. 7. Volatile alkali is a very powerful diaphoretic, and partic- ularly if exhibited in wine-whey ; twenty drops of fpirit of hartmom every half hour in half a pint of wine-whey, if the pi- nt Art. HI. 2. i. 8. SECERNENTIA. 35 tient be kept in a moderately warm bed, will in a few hours elicit moil profufe fweats. Neutral falts promote invifible perfpiration, when the fkin is not warmed much externally, as is evinced from the great thirit, which fucceeds a meal of fait provisions, as of red herrings. When thefe are fufficientlv* diluted with water, and the fkin kept warm, copious fweats without inflaming the habit, are the confequence. Half an ounce of vinegar faturatcd with volatile alkali, taken every hour or two hours, well anfwers this pur- pofe ; and is preferable perhaps in general to all others, where fweating is advantageous. Boerhaave mentions one cured of a fever by eating red-herrings or anchovies, which, with repeat- ed draughts of warm water or tea, would I fuppofe produce co- pious perfpiration. Antimonial preparations have alfo been of late much ufed with great advantage as diaphoretics. For the hiftory and ufe of thefe preparations I fhall refer the reader to the late writers on the Materia Medica, only obferving that the ftomach be- comes fo foon habituated to its ftimulus, that the fecond dofe may be confiderably increafed, if the firft had no operation. Where it is advifable to procure copious fweats, the emetics, as ipecacuanha, joined with opiates, as in Dover's powder, pro- duce this effect with greater certainty than the above. 8. We mufh not difmifs this fubjecl without obferving, that perfpiration is defigned to keep the (kin flexible; as the tears are intended to clean and lubricate the eve ; and that neither of thefe fluids can be confidered as excretions in their natural ftate, but as fecretions. See Clafs I. 1. 2. q. And that therefore the principal ufe of diaphoretic medicines is to warm the {kin, and thence in confequence, to produce the natural degree of in*, fenfible perfpiration in languid habits. 9. When the fkin of the extremities is cold, which is always a fign of prefent debility, the digeftion becomes frequently im- paired by aflbciation, and cardialgia or heartburn is induced from the vinous or acetous fermentation of the aliment. In this difeafe diaphoretics, which have been called cordials, by their action on the ftomach reftore its exertion, and that of the cu- taneous capillaries by their aflbciation with it, and the fkin be- comes warm, and the digeftion more vigorous. 10. But a blifter acts with more permanent and certain ef- fect, by ftimulating a part of the fkin, and thence affecting the whole of it, and of the ftomach by aflbciation, and thence re- moves the moft obftinate heartburns and vomitings. From this the principal ufe of blifters is understood, which is to in- vigorate the exertions of the arterial and lvmphatic vefTels of the ikin. I 6 - SECERNENTIA. Art. III. 2. 2. 1. fkin, producing an increafe of infenfible perfpiration, and of cu- taneous abforption ; and to increafe the action of the ftomach, and the confequent power of digeflion ; and thence by fympa- thy to excite all the other irritative motions : hence they relieve pains of the coM kind, which originate from defect of motion ; not from their introducing a greater pain, as fome have imagin- ed, but by itimulating the torpid veffels into their ufual action j and thence increafing the action and confequent warmth of the whole fkin, and of all the parts which are affociated with it. II. 1. Sialagogues. The preparations of mercury confiit of a folution or corrofion of that metal by fome acid ; and, when the dofe is known, it is probable that they are all equally effica- cious. As their principal ufe is in the cure of the venereal dif- eafe, they will be mentioned in the catalogue amongft the for- bentia. Where falivation is intended, it is much forwarded by a warm room and warm clothes ; and prevented by expofing the patient to his ufual habits of cool air and drefs, as the mer- cury is then more liable to go off by the bowels. 2. Any acrid drug, as pyrethrum, held in the mouth acts as a fialagogue externally by itimulating the excretory ducts of the falivary glands ; and the filiqua hirfuta applied externally to the parotid gland, and even hard fubftances in the ear, are faid to have the fame effect. Maftich chewed in the mouth emulges the fajivary glands. 3. The unwife cuflom of chewing and fmoking tobacco for many hours in a day not only injuies the falivary glands, pro- ducing drynefs in the mouth when this drug is not ufed, but I fufpect that it alio produces fcirrhus of the pancreas. The ufe of tobacco in this immoderate degree injures the power of di- geftion, by occafioning the patient to fpit out that faliva, which he ought to fwallow ; and hence produces that flatulency, which the vulgar unfortunately take it to prevent. The mucus, which is brought from the fauces by hawking, mould be fpit out, as well as that coughed up from the lungs ; but that which comes fpontaneoufly into the mouth from the falivary glands, fhould be fwallowed mixed with our food or alone for the purpofes of digeftion. See Clafs I. 2. 2. 7. III. 1. Expectorants are fuppofed to increafe the fecretion of mucus in the branches of the windpipe, or to increafe the perfpiration of the lungs fecreted at the terminations of the bron- chial artery. 2. If any tiling promotes expectoration toward the end of peripneumonies, when the inflammation is reduced by bleeding and gentle cathartics, fmall repeated blifters about the cheft, with tepid aqueous and mucilaginous or oily liquids, are more advantageous Art. HI. 2. 3. 3. SECERNENTIA. 37 advantageous than the medicines generally enumerated under this head ; the blifters by ftimulating into action the vefiels of the fkin produce by aflbciation a greater activity of thofe of the mucous membrane, which lines the branches of the wind- pipe, and air-cells of the lungs •, and thus after evacuation they promote the abforption of the mucus and confequent healing of the inflamed membrane, while the diluting liquids prevent this mucus from becoming too vifcid for this purpofe, or facilitate its expuition. Blifters, one at a time, on the fides or back, or on the fter- num, are alfo ufeful towards the end of peripneumonies, by pre- venting the evening accefs of cold fit, and thence preventing the hot fit by their hamulus on the fkin ; in the fame manner as five drops of laudanum by its ftimulus on the ftomach. For the increafed actions of the veflels of the fkin or ftomach excite a greater quantity of the fenforial power of aflbciation, and thus prevent the torpor of the other parts of the fyftem ; which, when patients are debilitated, is fo liable to return in the evening. 3. Warm bathing is of great fervice towards the end of perip- neumony to promote expectoration, efpecially in thofe children who drink too little aqueous fluids, as it gently increafes the action of the pulmonary capillaries by their confent with the cutaneous ones, and fupplies the fyftem with aqueous fluid, and thus dilutes the fecreted mucus. Some have recommended oil externally around the cheft, as well as internally, to promote expectoration •, and upon the nofe, when its mucous membrane is inflamed, as in common catarrh. IV. 1. Diuretics. If the fkin be kept warm, moft of thefe medicines promote fweat inftead of urine ; and if their dofe is enlarged, moft of them become cathartic. Hence the neutral falts are ufed in general for all thefe purpofes. Thofe indeed, which are compofed of the vegetable acid, are moft generally ufed as fudorifics 5 thofe with the nitrous acid as diuretics ; and thofe with the vitriolic acid as cathartics ; while thofe united with the marine acid enter our common nutriment, as a more general ftimulus. All thefe increafe the acrimony of the urine, hence it is retained a lefs time in the bladder ; and in confe- quence lefs of it is reabforbed into the fyftem, and the apparent quantity is greater, as more is evacuated from the bladder ; but it is not certain from thence, that a greater quantity is fecreted by the kidneys. Hence nitre, and other neutral falts, are erro- neoufly given in the gonorrhoea ; as they augment the pain of making water by their ftimulus on the excoriated or inflamed urethral They are alfo errcneoufly given in catarrhs or coughs, ere J 8 SECERNENTIA. Art. III. 2. 4. ^ v here the dilcharge is too thin and faline, as they increafe the frequency of coughing. 2. Balfam of Copaiva is thought to promote urine more than the other native balfams ; and common refin is faid to a£l as a powerful diuretic in horfes. Thefe are alfo much recommend- ed in gleets, and in lluor albus, perhaps more than they deferve ; they give a violet fmeli to the urine, and hence probably increafe the fecretion of it. Calcined egg-fhells are faid to promote urine, perhaps from the phofphoric acid they contain. 3. Cold air and cold water will increafe the quantity of urine by decreafmg the abforption from the bladder ; and neutral and alkalious fairs and cantharides by ftimulating the neck of the bladder to difcharge the urine as foon as fecreted ; and alcohol, as gin and rum, at the beginning of intoxication, if the body be kept cool, occafion much urine by inverting the urinary lymphat- ics, and thence pouring a fluid into the bladder, which never pai£. ed the kidneys. But it is probable, that thofe medicines, which give a fcent to the urine, as the balfams and refins, but particu- larly afparagus and garlic, are the only drugs, which truly increafe the fecretion of the kidneys. Alcohol however, ufed as above mentioned, ami perhaps great dofes of tincture of cantharides, may be confidcred as draitic diuretics, as they pour a fluid into the bladder by the retrograde action of the lymphatics, which are in great abundance fpread about the neck of it. See Se£t. XXIX. 3. V. Mild cathartics. The ancients believed that fome purg- es evacuated the bile, and hence were termed Cholagogues ; others the lymph, and were termed Hydragogues -, and that in flioit each cathartic felected a peculiar humour, which it dif- charged. The moderns have too haitily rejected this fyftem j the fuhjeel well deferves further obfervation. Calomel given in the dofe from ten to twenty grains, fo as to induce purging without the afhlbmce of other drugs, appears to me to particularly increafe the fecretion of bile, and to evacuate it ; aloe feems to increafe the fecretion of the inteftinal mucus ; and it is probable that the pancreas and fpleen may be peculiarly ftimulated into action by fome other of this tribe of medicines ; whilft others of them may Gmply ftimulate the inteftinal canal to evacuate its contents, as the bile of animals. It mud be re- marked, that all thefe cathartic medicines are fuppofed to be ex- hibited in their ufual dofes, otherwife they become draftic purg- and are treated of in the Oafs of Invertentia. VI. The mucus of the bladder is feen in the urine, when ides have been ufcd3, either internally or externally, in luch Art. til. 2. 7. r. SECERNENTIA. 39 fuch dofes as to induce the ftrangury. Spirit of turpentine is faid to have the fame effect. I have given above a dram of it twice a day floating on a glafs of water in chronic lumbago with- out this effect, and the patient gradually recovered. Phofpho- rus may poiTibly affect the mucous glands of the urethra like cantharides. See Impotentia, Clafs II. 2. 2. 3. VII. Aloe given internally feems to act chiefly on the rectum and fphincter ani, producing tenefmus and piles. Externally in clyfters or fuppofitories, common fait feems to act on that bow* el with greater certainty. But where the thread worms or afd&r- ides exift, 60 or 100 grains of aloes reduced to powder and boiled in a pint of gruel, and ufed as a clyfter twice a week for three months, has frequently deftroyed them. Might not the hairs of filiqua hirfuta be ufed in an injection for this purpofe ? See Clafs I. 1.4. 14. VIII. The external application of cantharides by ftimulating the excretory ducts of the capillary glands produces a great fe- cretion of fubcutaneous mucus with pain and inflammation ; which mucaginous fluid, not being able to permeate the cuticle, raifes it up ; a fimilar fecretion and elevation of the cuticle is produced by actual fire ; and by cauftic materials, as by the ap- plication of the juice of the root of white briony, or bruifed muf- tard-feed. Experiments are wanting to introduce fome acrid application into practice inftead of cantharides, which might not induce the ftrangury. Muftard-feed alone is too acrid, and if it be fuffered to lie on the fkin many minutes is liable to produce a flough and confer quent ulcer, and mould therefore be mixed with flour when ap- plied to cold extremities. Volatile alkali properly diluted might flimulate the fkin without inducing ftrangury. IX. The mild errhines are fuch as moderately ftimulate the membrane of the noftrils, fo as to increafe the fecretion of nafal mucus ; as is feen in thofe, who are habituated to take fnuff. The ftronger errhines are mentioned in Art. V. 2. 3. X. The fecretion of tears is increafed either by applying acrid fubftances to the eye ; or acrid vapours, which ftimulate the excretory duct of the lachrymal gland ; or by applying them to the noftrils, and ftimulating the excretory duct of the lachrymal fack, as treated of in the Section on Inftinct. Or the fecretion of tears is increafed by the aftbciation of the. motions of the excretory duct of the lachrymal fack with ideas of tender pleafure, or of hopelefs diftrefs, as explained in Sect. XVI. 8. 2. and 1. XI. The fecretion of fenforial power in the brain is proba- bly increafed by opium or wine, becaufe when taken in certairt Vol- I. R r r quantity 4o SECERNENTIA. Art. III. i. i. r. quantity an immediate increafe of itrength and activity fucceeds for a time, with confequent debility if the quantity taken be fo great as to intoxicate in the leaft degree. The neceflity of per- petual refpiration fhews, that the oxygen of the atmofphere Sup- plies the fource of the fpirit of animation ; which is conftantly expended, and is probably too fine to be long contained in the nerves after its production in the brain. Whence it is proba- ble, that the refpiration of oxygen gas mixed with common air mav increafe the fecretion of fcnforial power ; as indeed would apjrear from its exhilarating effect on moft patients. III. Catalogue of the Secernentia. I. Diaphoretics. i. Amomum zinziber, ginger. Carpophyllus aromati- cus, cloves. Piper indicum, pepper. Capficum. Cardamomum. Pimento, myrtus pimenta. Canella alba. Serpentaria virginiana, ariftolochia ferpenta- ria, guaiacum. Safiafras, laurus faflafras. Opium. Wine. 2. Eilential oils of cinnamon, laurus cinnamomum. Nut- meg, myriftica mofchata. Cloves, caryophyllus aro- maticus. Mint, mentha.' Camphor, laurus campho* ra. Ether. 3. Volatile falts, as of ammoniac and of hartfhorn. Sal cornu cervi. 4. Neutral falts, as thofe with vegetable acid ; or with marine acid, as common fait. Halex, red-herring, anchovy. 5. Preparations of antimony, as emetic tartar, antimoni- um tartarizatum, wine of antimony. James's pow- der. 6. External applications. Blifters. Warm bath. Warm air. Exercife. Friction. 7. Cold water with fubfequent warmth. II. Sialagogues. Preparations of mercury, hydrargyrus. Py- rethrum, anthemis pyrethrum, tobacco, cloves, pepper, cowhage, ftizolobium fjliqua hirfuta. Maftich, pifta- cia lentifcus. III. Expectorants. 1. Squill, fcilla maritima, garlic, leek, onion, allium, afa- fcetida, ferula afafoetida, gum ammoniac, benzoin, tar, pix liquida, balfam of Tolu. 2. Root of feneka, polygala feneka; of elecampane, inula helenium. 3, Marfh«mallow Art. III. 3. 3. 3. SECERNENTIA. 41 3. Marfti-mallow, althsea, coltsfoot, tuffilago farlara, gum arabic, mimofa nilotfea, gum tragacanth, aftragalus tragacantha. Decoction of barley, hordeum diftichon. ExprefTed oils. Spermaceti, foap. Extras of liquor- ice, glycyrrhiza glabra. Sugar. Honey. 4. Externally blifters. Oil. Warm bath. IV. Mild diuretics. 1. Nitre, kali acetatum, other neutral falts. 2. Fixed alkali, foap, calcined egg-fhells. 3. Turpentine. Balfam of Copaiva. Refin. Olibanum, 4. Afparagus, garlic, wild daucus. Parfley, apium. Fen- nel, fasniculum, pareira brava, cifiampelos ? 5. Externally cold air, cold water. 6. Alcohol. Tincture of cantharides. Opium. V. Mild cathartics. 1. Sweet fubacid fruits. Prunes, prunus domeftica. Caf- fia fiftula. Tamarinds, cryftals of tartar, unrefined fugar. Manna. Honey. 2. Whey of milk, bile of animals. 3. Neutral falts, as Glauber's fait, vitriolated tartar, fea- water, magnefia alba, foap. 4. Gum guaiacum. Balfam of Peru. Oleum ricini, caftor-oil, oil of almonds, oil of olives, fulphur. 5. Senna, caffia fenna, jalap, aloe, rhubarb, rheum paU matum. 6. Calomel. Emetic tartar, antimonium tartarizatum. VI. Secretion of mucus of the bladder is increafed by can- tharides, by fpirit of turpentine ? Phofphorus ? VII. Secretion of mucus of the rectum is increafed by aloe internally, by various clyfters and fuppofitories externally. VIII. Secretion of fubcutaneous mucus is increafed by blif- ters of cantharides, by application of a thin flice of the frefh root of white briony, by fmapifms, by root of horfe- radifh, cochlearia armoracia. Volatile alkali. IX. Mild errhines. Marjoram. Origarium. Mar Urn, tobacco. X. Secretion of tears is increafed by vapour of fliced onion, of volatile alkali. By pity, or ideas of hopelefs diftrefs. XI. Secretion of fenforial power in the brain is probably in- creafed by opium, by wine, and perhaps by oxygen <: added to the common air in refpiration. T. 42 SORBENTIA. Art. IV. it. Art! IV. SORBENTIA. ! 1. Those things which increafe the irritative motions, which conftitute abforption, are termed forbentia •, and are as various as the abforbent vefiels which they flimulate into action. i. Cutaneous abforption is increafed by auftere acids, as of I vitriol -, hence they are believed to check colliquative fweats, and to check the eruption of fmall-pox, and contribute to the cure of the itch, and tinea ; hence they thicken the faliva in the mouth, as lemon-juice, crab-juice, floes. 2. Abforption from the mucous membrane is increafed by opi- um, and Peruvian bark, internally j and by blue vitriol externally. Hence the expectoration in coughs, and the mucous difcharge from the urethra, are thickened and leftened. 3. Abforption from the cellular membrane is promoted by bitter vegetables, and by emetics, and cathartics. Hence mat- ter is thickened and leffened in ulcers by opium and Peruvian bark ; and ferum is abforbed in anafarca by the operation of emetics and cathartics. 4. Venous abforption is increafed by acrid vegetables ; as water-crefs, cellery, horfe-radifh, muftard. Hence their ufe in fea-fcurvy, the vibices of which are owing to a defect of ven- ous abforption •, and by external ftimulants, as vinegar, and by electricity, and perhaps by oxygen. 5. Inteftinal abforption is increafed by aftringent vegetables, as rhubarb, galls ; and by earthy falts, as alum ; and by argilla- ceous and calcareous earth. 6. Hepatic abforption is increafed by metallic falts, hence calomel and fal martis are fo efficacious in jaundice, worms^ chlorofis, drcpfy. 7. Venereal virus in ulcers is abforbed by the ftimulus of mercury ; hence they heal by the ufe of this medicine. 8. Venefettion, hunger, thirft, and violent evacuations, in- creafe all abforptions ; hence fweating produces coflivenefs. 9. Externally bitter aftringent vegetables, earthy and metal- lic falts, and bandages, promote the abforption of the parts on which they are applied. 1 o. All thefe in their ufual dofes do not increafe the natur- al heat i but they induce coflivenefs, and deep-coloured urine with earthy fediment. In greater dofes they invert the motions of the ftomach and lacteaii , and hence vomit or purge, as carduus benedictus, rhubarb. Art. IV. 2. i . i . SORBENTI A. 43 rhubarb. They promote perfpiration, if the fkin be kept warm ; as camomile tea, and teftaceous powders, have been ufed as fudorifics. The preparations of antimony vomit, purge, or fweat, either according to the quantity exhibited, or as a part of what is giv- en is evacuated. Thus a quarter of a grain of emetic tartar (if well prepared) will promote a diaphorefis, if the fkin be kept warm ; half a grain will procure a ftool or^fro firft, and fweat- ing afterward ; and a grain will generally vomit, and then purge, and laftly fweat the patient. In lefs quantity it is prob- ble, that this medicine ads like other metallic falts, as fteel, zinc, or copper in fmajl dofes ; that is, that it ftrengthens the fyftem by its ftimulus. As camomile and rhubarb in different dofes vomit, or purge, or a6t as flimulants fo as to ftrengthen the fyftem. Some of the medicines of this clafs of forbentia have been termed tonics by fome authors, as giving due tone to the ani- mal fibre. But it fhould be obferved, that tone is a mechanical term, applicable only to mufical firings, and like bracing and re- laxation, cannot be applied to animal life except metaphorically. The fame may be obferved of the word reaction, ufed by fome modern authors, which in its proper fignification is a mechan- ical term inapplicable to the laws of life except metaphorically. II. Observations on the Sorbentia. I. 1. As there is great difference in the apparent ftructure of the various glands, and of the fluids which they felect from the blood, thefe glands muft poffefs different kinds of irritabili- ty, and are therefore ftimulated into ftronger or unnatural ac- tions by different articles of the materia medica, as fhewn in the fecernentia. Now as the abforbent veffels are likewife glands, and drink up orw felect different fluids, as chyle, water, mucus, with a part of every different fecretion, as a part of the bile, a part of the faliva, a part of the urine, &c. it appears, that thefe abforbent veffels muft likewife poffefs different kinds of irrita- bility, and in confequence muft require different articles of the materia medica to excite them into unufual action. This part of the fubjecl has been fo little attended to, that the candid reader will find in this article a great deal to excufe. It was obferved, that fome of the fecernentia did in a lefs de- gree increafe abforption, from the combination of different prop- erties in the fame vegetable body ; for the fame reafon fome of the clafs of forbentia produce fecretion in a lefs degree, as thole bitters which ^have alio an aroma in their compofition ; thefe 44 30RBENTI A. Art. IV. 2.1.2. are known from their increafing the heat of the fyftem above its ufual degree. It muft alio be noted, that the actions of every part of the abforbent fyftem are fo affociated with each other, that the drugs which ftimulate one branch increafe the action of the whole ; and the torpor or quiefcence of one branch weakens the exertions of the whole ; or when one branch is excited into flronger action, fome other branch has its actions weakened or inverted. Yet though peculiar branches of the abforbent fyf- tem are ftimulated into action by peculiar fubftances, there are other fubftances which feem to ftimulate the whole fyftem, and that without immediately increafing any of the fecretions ; as thofe bitters which poffefs no aromatic fcent, at the head of which ftands the famed Peruvian bark, or cinchona. 2. Cutaneous abforption. I have heard of fome experi- ments, in which the body- was kept cold, and was thought to abforb more moifture from the atmofphere than at any other time. This however cannot be determined by ftatical experi- ments ; as the capillary veflels, which fecrete the perfpirable matter, muft at the fame time have been benumbed by the cold ; and from their inaction there could not have been the ufual wafte of the weight of the body j and as all other mufcular ex- ertions are beft performed, when the body poffeffes its ufual de- gree of warmth, it is conclufive, that the abforbent fyftem fhould likewife do its office beft, when it is not benumbed by external cold. The auftere acids, as of vitriol, lemon-juice, juice of crabs and floes, ftrengthen digeftion, and prevent that propenfity to fweat fo ufual to weak convalefcents, and diminish the colliquative fweats in hectic fevers ; all which are owing to their increafing the action of the external and internal cutaneous abforption. Hence vitriolic acid is given in the fmall-pox to prevent the too hafty or too copious eruption, which it effects, by increafing the cutaneous abforption. Vinegar, from the quantity of alcohol which it contains, exerts a contrary effect to that here defcrib- ed, and belongs to the incitantia ; as an ounce of it promotes fweat, and a flufhing of the fkin ; at the fame externally it acts .is a venous abforbent, as the lips become pale by moiftening them with it. And it is faid, when taken internally in great and continued quantity, to induce palenefs of the fkin, and foft- nefs of the bones. The fweet vegetable acids, as of feveral ripe fruits, are among the torpentia ; as they are lefs (timulating than the general food of this climate, and are hence ufed in inflammatory difeafes. Where the quantity of fluids in the fyftem is much leffened, as Art. IV. 2. i. 3. SORBENTIA. 45 •as in hectic fever, which has been of fome continuance, or in fpurious peripneumony, a grain of opium given at night will fometimes prevent the appearance of fweats ; which is owing to the ftimulus of opium increafing the actions of the cutaneous abforbents, more than thofe of the fecerning veflels of the (kin. Whence the iecretion of perfpirable matter is not decreafed, but its appearance on the fkin is prevented by its more facile abforption. , , 3. There is one kind of itch, which feldonf appears between the fingers, is the lead infectious* and mod difficult to eradicate, and which has its cure much facilitated by the internal ufe of acid of vitriol. This difeafe confifts of fmall ulcers in the fkin, which are healed by whatever increafes the cutaneous abforp- tion. The external application of fulphur, mercury, and acrid vegetables, acts on the fame principle ; for the animalcula, which are feen in thefe puftules, are the effect, not the caufe, of them ; as all other ftagnating animal fluids, as the femen itfelf, abounds with fimilar microfcopic animals. See Dyfentery, Clafs II. 1. 3. 18. 4. Young children have fometimes an eruption upon the head called tinea, which difcharges an acrimonious ichor inflaming the parts, on which it falls. This eruption I have feen fubmit to the internal ufe of vitriolic acid, when only wheat-flour was applied externally. This kind of eruption is likewife frequent- ly cured by teftaceous powders ; two materials fo widely differ- ent in their chemical properties, but agreeing in their power of promoting cutaneous abforption. II. Abforption from the mucous membrane is increafed by applying to its furface the auftere acids, as of vitriol, lemon-juice, crab-juice, floes. When thefe are taken into the mouth, they immediately thicken, and at the fame time lefTen the quantity of the faliva ; which laft circumftance cannot be owing to their coagulating the faliva, but to their increafing the abforption of the thinner parts of it. So alum applied to the tip of the tongue does not flop in its action there, but independent of its diffufion it induces cohefion and corrugation over the whole mouth. (Cul- len's Mat. Med. Art. Aftringentia. ) Which is owing to the aflbciation of the motions of the parts or branches of the abforb- ent fyftem with each other. Abforption from the mucous membrane is increafed by opium taken internally in fmall dofes more than by any other medicine, as is feen in its thickening the expectoration in coughs, and the difcharge from the noftrils in catarrh, and perhaps the difcharge from the urethra in gonorrhoea. The bark feems next in pow- er for all thefe p'urpofes. Externally 4<$ SORBENTlA. Art. IV. 2. 3. 1, Externally flight folutions of blue vitriol, as two or three grains to an ounce of water, applied to ulcers of the mouth, or to chancres on the glans penis, more powerfully induce them to heal than any other material. Where the lungs or urethra are inflamed to a confiderable degree, and the abforption is fo great, that the mucus is already too thick, and adheres to the membrane from its vifcidity, opi- ates and bitter vegetable and auftere acids are improper ; and mucilaginous diluent fhould be ufed in their ftead with venefec- tion and torpentia. III. 1. Abforption from the cellular membrane, and from all the other cavities of the body, is too flowly performed in fome conftitutions ; hence the bloated pale complexion ; and when this occurs in its greateil degree, it becomes an univerfal dropfy. Theie habits are liable to intermittent fevers, hyfteric paroxyfms, cold extremities, indigeftion, and all the fymptoms of debility. The abforbent fyftem is more fubjecl to torpor or quiefcence than the fecerning fyftem, both from the coldnefs of the fluids which are applied to it, as the moiflure of the atmofphere, and from the coldnefs of the fluids which we drink ; and alfo from its being itimulated only by intervals, as when we take our food 5 whereas the fecerning fyftem is perpetually excited into action by the warm circulating blood ; as explained in Sect. XXXII. 2. The Peruvian bark, camomile flowers, and other bitter drugs, by ftimulating this cellular branch of the abforbent fyftem prevents it from becoming quiefcent ; hence the cold paroxyfms of thofe agues, which arife from the torpor of the cellular lymph- atics, are prevented, and the hot fits in confequence. The patient thence preferves his natural heat, regains his healthy colour, and his accuftomed ftrength. Where the cold paroxyfm of an ague originates in the abforb- ents of the liver, fpieen, or other internal vifcus, the-addition of iteel to vegetable bitters, and efpecially after the .ufe of one dole of calcmel, much advances the cure. And where it originates in any part of the fecerning fyftem, as is probably the cafe in fome kinds of agues, the addition of opium in the dofe of a grain and half, given about an hour be- fore the accefs of the paroxyfm, or mixed with chalybeate and bitter medicines, enfures the cure. Or the fame may be effected by wine given inftead of opium before the paroxyfm, fo as near* ly to intoxicate. Thefe three kinds of agues are thus diftinguifhed ; the firft is not attended with any tumid or indurated vifcus, which the peo- ple call an ague cake, and which is evident to the touch. The iecond is accompanied with a tumid vifcus i and the laft has generally, Art. IV. 2. 3. p SORBENTIA, 47 generally, I believe, the quartan type, and is attended with fome degree of arterial debility. The bark of the broad-leaved willow or falix caprea of Linne- us, is much recommended as equal to the Peruvian bark given in the fame or in greater quantity by Mr. White of Bath. Ob- ferv. and Exper. on broad-leafed willow. Vernor and Hood$ London* A Dr. Gunz in Germany recommends alfo as a fub- ftitute for Peruvian bark, the bark of fix fpecies of willow, the falix alba, pentandra, fragilis, eaprea* yitellina, and amygdaiina* Dr. Gunz believes fome of thefe barks to be more efficacious than the Peruvian. And as fome of thefe willow-barks may be procured in great quantity, as they are (tripped off from the wil- low twigs ufed by the bafket-makers in many parts of the coun- try in the vernal months, it would feem to be an article worth attending to* The root of geum urbanum, avens, is recommended as a fub- ftitute for Peruvian bark by Dr. Vogel, and faid to cure the quartan ague given in the dofe of half a dram every hour through the day. The datifca cannabina of Linneus is alfo faid to equal the Peruvian bark in its febrifuge virtues. Medical and Phyfical Journal, Vol. I. p. 191. 3-. This clafe of abforbent medicines are faid to decreafe irri« lability. After any part of our fyftem has been torpid or qui- efoent, by whatever caufe that was produced, it becomes after- wards capable of being excited into greater motion by fmall ftimuli ; hence the hot fit of fever fuceeeds the cold one. As thefe medicines prevent torpor or quiefcence of parts of the fyf- tem, as cold hands or feet, which perpetually happen to weak conftitutions, the fubfequent increafe of irritability of thefe parts is likewife prevented* 4* Thefe abforbent medicines, including both the bitters* and metallic falts, and opiates, are of great ufe in the dropfy by their promoting univerfal abfbrption ; but here evacuations are likewife to be produced, as will be treated of in the Invertentia* 5. The matter in ulcers is thickened, and thence rendered lefs corrofive, the faline part of it being reabforbed by the ufe of bitter medicines ; hence the bark is ufed with advantage in the cure of ulcers* 6. Bitter medicines ftrengthen digeftion by promoting the ^bforption of chyle ; hence the introduction of hop into the po- tation ufed at our meals, which as a medicine may be taken ad- vantageoufiy, but, like other unnecefTary ftimuli, mud be injuri- ous as an. article of our daily diet. The hop may perhaps in fome degree Contribute t0~ the pro- duction of gravel in the kidneys, as our intemperate wine-drink- Vot» L S i i era 48 SORBENTIA. Art. IV. 2. 3. 7. ers are more fubject to the gout, and ale-drinkers to the gravel ; in the formation of both which difeafes, there can be no doubt, but that the. alcohol is the principal, if not the only agent. 7. Vomits greatly increafe the abforption from the cellular membrane, as fquill, and foxglove. The fquill mould be given in the dole of a grain of the dried root every hour, till it ope- rates upwards and downwards. Four ounces of the frefh leaves of the foxglove mould be boiled from two pounds of water to one, and half an ounce of the decoction taken every two hours for four or more dofes. This medicine by ftimulating into in- verted action the abforbents of the iiomach, increafes the direct action of the cellular lymphatics. Another more convenient way of afcertaining the dofe of foxglove is by making a faturated tincture of it in proof fpirit ; which has the twofold advantage of being invariable in its origin- al ilrength, and of keeping a long time as a mop-medicine without lofmg any of its virtue. Put two ounces of the leaves of purple foxglove, digitalis purpurea, nicely dried, and coarfely powdered, into a mixture of four ounces of rectified fpirit of wine and four ounces of water; let the mixture (land by the' fire-fide twenty-four hours frequently (baking the bottle, and thus making a faturated tincture of digitalis *, which mud be poured from the fediment or pafled through filtering paper. Some perfon has lately objected to the quantity of the dried leaves of digitalis ufed in this tincture as an unnecefTary ex- penfe ; not knowing that the plant grows fpontaneoufly by cart- loads in all fandy fituations, and not recollecting that the cer- tainty of procuring this medicine at all times of the year, and from all fhops of the fame degree of ftrength, is a circumftance of great importance. As the fize of a drop is greater or lefs according to the fize of the rim of the phial from which it is dropped, a part of this faturated tincture is then directed to be put into a two-ounce phial, for the purpofe of afcertaining the fize of the drop. Thirty drops of this tincture are directed to be put into an ounce of mint-water for a draught to be taken twice or thrice a day, till it reduces the anafarca of the limbs, or removes the difficultv of breathing in hydrothorax, or till it induces ficknefs. And if thefe do not occur in two or three days, the dofe muft be gradually increafed to forty or fixty drops, or further. A lady, who was 92 years of age, was feized fuddenly, early in the morning, with great difficulty of refpiration, which con- tinued in greater or lefs degree in fpite of many medicines for two or three weeks. Her legs were then become oedematous, and fne could not lie down horizontally. On taking thirty drops Art. IV. 2. 3. 8. SORBENTIA. 49 drops of the faturated tincture of digitalis from a two-ounce phial twice a day, (he became free from the difficult refpira- tion, and her legs became lefs fwelled, in two or three days. She has repeated this medicine about once a month for more than a year, with tincture of bark at intervals, and half a grain of opium at night, and retains a tolerable (late of health. From the great ftimulus of this medicine the ftomach is ren- dered torpid with confequent ficknefs, which continues many hours and even days, owing to the great exhauftion of its fenfo- rial power of irritation ; and the action of the heart and arteries becomes feeble from the deficient excitement of the fenforial power of aflbciation j and laftly, the abforbents of the cellular membrane act more violently in confequence of the accumula- tion of the fenforial power of aflbciation in the torpid heart and arteries, as explained in Suppl. I. 12. A circumftance curioufly fimilar to this occurs to fome peo- ple on fmoking tobacco for a more time, who have not been ac- cuftomed to it. A degree of ficknefs is prefently induced, and the pulfations of the heart and arteries become feeble for a fhort time, as in the approach to fainting, owing to the direct fym- pathy between thefe and the ftomach, that is from defect of the excitement of the power of aflbciation. Then there fuc- ceed a tingling, and heat, and fometimes fweat, owing to the in- creafed action of the capillaries, or perfpirative and mucous glands ; which are occafloned by the accumulation of the fen- forial power of aflbciation by the weaker action of the heart and arteries, which now increafes the action of the capillaries. 8. Another method of increafmg abforption from the cellu- lar membrane is by warm air, or by warm iteam. If the fwell- ed legs of a dropfical patient are enclofed in a box, the air of which is made warm by a lamp or two, copious fweats are foon produced by the increafed action of the capillary glands, which are feen to itand on the fkin, as it cannot readily exhale in fo fmall a quantity of air, which is only changed fo faft as may be neceflary to permit the lamps to burn. At the fame time the lymphatics of the cellular membrane are itimulated by the heat into greater action, as appears by the fpeedy reduction of the tumid legs. It would be well worth trying an experiment upon a perfon labouring under a general anafarca by putting him into a room filled with air heated to 1 20 or 13© degrees, which would prob- ably excite a great general diaphovefis, and a general cellular ab- forption both from the lungs and every other part. And that air of fo great heat may be borne for many minutes without great je SORBENTIA. Art, IV. 2. 3. 9, great inconvenience was fhewn by the experiments made in heated rooms by Dr. Fordyce and others. Philof. Tranf. Another experiment of ufing warmth in anafarca, or in oth- er difeafes, might be by immernng the patient in warm air, or in warm fleam, received into an oil-fkin bagj> or bathing-tub of tin, fo managed, that the current of warm air or fleam (hould pafs round and cover the whole of the body except the head, which might not be expofed to it \ and thus the abforbents of the lungs might be induced to act more powerfully by fympa- thy with the fkin, and not by the ftimulus of heat. See Ufes of Warm Bath, Art. II. 2. 2. 1. A warm faline pediluvium has often been ufed with fuccefs, to remove fwellings of the legs from deficient adtion of the ab- forbents of the lower extremities -y the quantity of fea-falt fhould be about one thirtieth part of the water, which with about one eightieth part of fulphuric magnefian fait, called magnefia vitri- olata, or bitter cathartic fait, conftitutes the medium flrength of the fea-water round this ifland, according to the experiments of Mr. Brownrig. In fuch a pediluvium the fwelled legs fhould be immerfed for half an hour every night for a fortnight, at the heat of about 90 or 98 degrees. Dr. Reid, in a Treatife on Sea-bathing °, Cadell and Davis, London \ recommends an univerfal warm-bath of fea-water, in cedematous fwellings, apparently with great fuccefs, and well advifes friction to be diligently ufed in the bath on the tumid limbs, always rubbing them from their extremities towards the trunk of the body, and not the contrary way ; as this mud moft facilitate the progrefs of the fluids in the abforbent fyilem ; . though thefe veiTels are furnifhed with valves to prevent its re- turn. In thefe baths the ftimulus of the fait is added to that of the heat. See Art. II. 2. 2. 1. 9. Another method of increafing abforption from the cellu- lar membrane, which has been ufed in dropfies, has been by the great or total abftinence from fluids. This may in fome degree be ufed advantageoufly in fubjecls of too great corpulency, but if carried to excefs may induce fevers, and greater evils than it is defigned to counteract, befides the perpetual exiflence of a painful third. In mofl dropfies the third already exiding ihews, that too little diluent fluid, and not too much, is prefent in the circulation, IV. 1 . Venous abforption. Cellery, watercrcflcs, cabbages, and many other vegetables of the clafs tetradynamia, do -not in- crezfc the heat of the body (except thofe, the acrimony of which approaches to corrofion), and hence they feem alone, or princi- pal to act on the venous fydem j the extremities of which we ha\ro Art. IV. 2. 4. 2. SORBENTIA. 5 1 have (hewn are abforbents of the red blood, after it has palled the capillaries and glands. 2.[ In the fea-fcurvy and petechial fever the veins do not per- fectly perform this office of abforption ; and hence the vibices are occafioned by blood ftagnating at their extremities, or ex- travafated into the cellular membrane. And this clafs of vegeta- bles, ftimulating the veins to perform their natural abforption, without increafing the energy of the arterial action, prevents future petechia, and may aflift the abforption of the blood al- ready ftagnated,as fbon asks chemical change renders it proper for that operation. 3. The fluids, which are extravafated, and received into the cells of the cellular membrane, feem to continue there for many days, fo as to undergo fome chemical change, and are then taken up again by the mouths of the cellular abforbents. But the new veffels produced in inflamed parts, as they communicate with the veins, are probably abforbed again by the veins along with the blood which they contain in their cavities. Hence the blood, which is extravafated in bruifes of vibices, is gradually many days in difappearing ; but after due evacuations the in- flamed veiTels on the white of the eye, if any ftimubnt lotion is applied, totally difappear in a few hours. Amongft abforbents affecting the veins we fhould therefore add tlie external application of ftimulant materials 5 as of vine- gar, which makes the lips pale on touching them. Friction, and electricity. 4. Haemorrhages are of two kinds, either arterial, which are attended with inflammation •, or venous, from a deficiency in the abforbent power of this fet of veiTels^ In the former cafe the torpentia are efficacious ♦, in the latter fteel, opium, alum, and all the tribe of forbentia, are ufed with fuccefs. 5. Sydenham recommends vegetables of the clafs tetradyna- mia in rheumatic pains left after the cure of intermittents. Thefe pains are perhaps fimilar to thofe of the fea-fcurvy, and feem to arife from want of abforption in the affected part, and hence are relieved by the fame medicines. V. 1. Inteftinal abforption. Some aftringent vegetables, as rhubarb, may be given in fuch dofes as to prove cathartic ; and, after a part of it is evacuated from the body, the remaining part augments the abforption of the iriteftines ; and acts, as if a fimilar dofe had been exhibited after the operation of any oth- er purgative. Hence 4 grains of rhubarb fcrengthen the bow- els, 30 grains firft empty them. 2. The earthy falts, as alum, increafe the inteftinal abforp- tion, and hence induce conftipation in their ufual dole ; alum is SZ SORBENTIA. Art. IV. 2. 5. 3. is faid fometimcs to cure intermittents, perhaps when their feat is in the inteftines, when other remedies have failed. It is ufe- ful in the diabetes, by exciting the abforbents of the bladder in- to their natural action ; and combined with refin is efteemed in the fluor albus, and in gleets. Lime-done or chalk, and probably gypfum, poffefs effects in fome degree fimilar, and in- creafe the abforption of the inteftines ; and thus in certain do- fes reftrain fome diarrhoeas, but in greater dofes alum I fup- pofe will act as a cathartic. Five or ten grains produce confti- pation, 20 or 30 grains are either emetic or cathartic. 3. Earth of alum, tobacco-pipe clay, marl, Armenian bole, lime, crab's eyes or claws, and calcined hartfhorn, or bone afh- es, reftrain fluxes ; either mechanically by fupplying fomething like mucilage, or oil, or rollers to abate the friction^f the ali- ment over inflamed membranes *, or by increafing their abforp- tion. The two laft confift of calcareous earth united to phof- phoric acid, and the Armenian bole and marl may contain iron. By the confent between the inteftines and the fkin 20 grains of Armenian bole given at going into bed to hectic patients will frequently check their tendency to fweat as well as to purge, and the more certainly if joined with one grain of opium. VI. 1. Abforption from the liver, ftomach, and other vifcera. When inflammations of the liver are fubdued to a certain de- gree by venefection, with calomel and other gentle purges, fo that the arterial energy becomes weakened, four or eight grains of iron-filings, or of fait of fteel, with the Peruvian bark, have wonderful effect in curing the cough, and reftoring the liver to its ufual fiae and fanity ; which it feems to effect by increafing the abforption of this vifcus. The fame I fuppofe happens in refpect to the tumours of other vifcera, as of the fpleen, or pan- creas, fome of which are frequently enlarged in agues. 2. Haemorrhages from the nofe, rectum, kidneys, uterus, and other parts, are frequently attendant on difeafed livers ; the blood being impeded in the vena portarum from the decreafed power of abforption, and in confequence of the increafed fize of this vifcus. Thefe hemorrhages after venefection, and a mer- curial cathartic, are molt certainly reftrained by fteel alone, or joined with an opiate ; which increafe the abforption and di- minifh the fize of the livet. Chalybeates may alfo reftrain thefe haemorrhages by their promoting venous abforption, though they exert their principal effect upcn the liver. Hence alfo opiates, and bitters, and vit- riolic acid are advantageoufly ufed along with them. It muft be added that fome hemorrhages recur by periods like the par- oxyfms Art. IV. 2. 6. 3. SORBENTIA. 53 oxyfms of intermittent fevers, and are thence cured by the fame treatment. 3. The jaundice is frequently caufed by the infipidity of the bile, which does not ftimulate the gall-bladder and bile-duels in- to their due action ; hence it ftagnates in the gall-bladder, and produces a kind of cryftallization, which is too large to pafs in- to the interlines, blocks up the bile-duct, and occafions a long and painful difeafe. A paralyfis of the bile-duel: produces a fimilar jaundice, but without pain. 4. Worms in fheep called flukes are owing to the dilute Mate of the bile ; hence they originate in the inteftines, and thence migrate into the biliary ducts, and corroding the liver produce ulcers, cough, and hectic fever, called the rot. In hu- man bodies it is probable the inert ftate of the bile is one caufe of the production of worms ; which infipid ftate of the bile is owing to deficient abforption of the thinner parts of it ; hence the pale and bloated complexion, and fwelled upper lip, of wormy children, is owing to the concomitant deficiency of abforption from the cellular membrane. Salt of fteel, or the ruil of it, or filings of it, with bitters, increafe the acrimony of the bile by promoting the abforption of its aqueous part ; and hence deftroy worms, as well by their immediate action on the inteftines, as on the worms themfelves. The cure is facilitated by premi- iing a purge with calomel. See Clafs I. 2. 3. 9. 5. The chlorofis is another difeafe owing to the deficient ac- tion of the abforbents of the liver, and perhaps in fome degrea alfo to that of the fecretory veflels, or glands, which compofe that vifcus. Of this the want of the catamenia, which is gen- erally fuppofed to be a caufe, is only a fymptom or confequence. In this complaint the bile is deficient perhaps in quantity, but certainly in acrimony, the thinner parts not being abforbed from it. Now as the bile is probably of great confequence in the pro- cefs of making the blood ; it is on this account that the blood is fo deftitute of red globules ; which is evinced by the great palenefs of thefe patients. As this ferbus blood mud exert lefs ftimulus on the heart, and arteries, the pulfe in confequence becomes quick as well as weak, as explained in Sect. XII. 1. 4. The quicknefs of the pulfe is frequently fo great and perma- nent, that when attended by an accidental cough, the difeafe may be miftaken for hectic fever •, but is cured by chalybeate , and bitters exhibited twice a day ; with half a grain of ODium, and a grain of aloe every night ; and the expected catamenia appears in confequence of a reftoration of the due quantity of red blood. This and the two former articles approach to the difeafe termed paral/fis of the liver. Sect. XXX. 4. 6. It 54 SORBENTIA. Art. IV, 2. 6. 6* 6. It fecms paradoxical, that the fame treatment with chalyb- eates, bitters, and opiates, which produces menftruation in chlo- rotic patients, fhould reprefs the too great or permanent men- ftruation, which occurs in weak conftitutions at the time of life when it fhould ceafe, This complaint is a haemorrhage owing to the debility of the abforbent power of the veins, and belongs to the paragraph on venous abforption above defcribed, and is thence curable by chalybeates, alum, bitters, and particularly by the exhibition of a grain of opium every night with five grains of rhubarb. As fteel is foluble in the gaftric acid, perhaps the bell: way of giving it may be in fine filings, or in a fleel-powder prepared in the following manner : diflblve green vitriol in water, add a few bits of iron to the folution, to precipitate any copper which may be accidentally in it ; precipitate this folution by fait of tar- tar, kali preparatum. Add to the precipitate two or three times its quantity of charcoal powder, mix and put them into a cruci* ble covered with a tile, and give them a red heat for an hour* An impalpable powder of iron will be produced, which ought all of it to obey the magnet* 7. Metallic falts fupply us with very powerful remedies for" promoting abforption in dropfical cafes ; which frequently are caufed by enlargement of the iiver. Firft, as they may be giv- en in fuch quantities as to prove ftrongly cathartic, of which more will be laid in the article on invertentia ; and then, when their purgative quality ceafes, like the effecl: of rhubarb, their ab» forbent quality continues to atl. The falts of mercury, filver, copper, iron, zinc, antimony, have all been ufed in the dropfy ; either fmgly for the former purpofe, or united with bitters for the latter, and occafionally with moderate but repeated opiates. 8. From a quarter of a grain to half a grain of blue vitriol given every four or fix hours, is faid to be very efficacious in ob- ftinate intermittents ; which alfo frequently arife from an en- larged vifcus, as the liver or fpleen, and are thence owing to the deficient abforption of the lymphatics of that vifcus. A quarter of a grain of white arfenic, as I was informed by a furgeon of the army, cures a quartan ague with great certainty, if it be given an hour before the expected fit. This dole he faid was for a ro- bufl man, perhaps one eighth of a grain might he given and re- peated with greater la fety and equal efficacy. Dr. Fowler has given many fuccefsfu.l cafes in his trcatife on this fubjecl:. He prepares it by boiling fixty-four grains of , white arfenic in a Florence flafk along with as much pure vegeta- ble fixed alkali in a pint of diftilled water till they are diflblv- ed, and then adding as much diftilled water as will make the whole Art. IV. 2. .6. 9. SORBENTI A. 5 1 whole exactly fixteen ounces. Hence there are four grains c arfenic in every ounce of the folution. This mould be put into a phial of fuch a fize of the edge of its aperture, that fixty drops may weigh one dram, which will contain half a grain of arfenic. To children from two years old to four he gives from two to five drops three or four times a day. From five years old to feven, he dircts feven or eight drops. From eight years old to twelve, he directs from feven to ten drops. From thirteen years old to eighteen he directs from ten to twelve drops* From eighteen upwards, tv/elve drops. In fo powerful a medicine it is always . prudent to begin with fmaller dofes, and gradually to ihcreafe them. A faturated folution of arfenic in water is preferable I think to the above operofe preparation of it ; ' as no error can happen in weighing the ingredients, and it more certainly therefore pof- fefles an uniform ftrength. Put much more white arfenic re- duced to powder into a given quantity of diftilled water, than can be diflblved in it. Boil it for half an hour hi a Florence flalk, or in a tin fauce-pan ; let it ftand to fubfide, and filter it through paper. My friend Mr. Greene, a furgeon at Bree- wood in StafFordfhire, afTured me, that he had cured in one fea- fon agues without number with this faturated folution ; that he found ten drops from a two-ounce phial given thrice a day was a full dofe for a grown perfon, but that he generally began with five. 9. The manner, in which arfenic acts in curing intermittent fevers cannot be by its general ftimulus, becaufe no intoxication or heat follows the ufe of it ; nor by its peculiar ftimulus on any part of the fecreting fyftem, fince it is not in fmall doles fucceeded by any increafed evacuation, or heat, and muft there- fore exert its power, like other articles of the forbentia, on the abforbent fyftem. In what manner it deftroys life fo fuddenly is difficult to underftand, as it does not intoxicate like many vegetable poifons, nor produce fevers like contagious matter. When applied externally it feems chemically to deftroy the part like other cauftics. Does it chemically deftroy the ftomach, and life in confequence ? or does it deftroy the action of the ftomach by its great ftimulus, and life in confequence of the fympathy between the ftomach and the heart ? This lafl appears* to be the mod probable mode of its operation* The fuccefs of arfenic in the cure of intermittent fevers I iuf- pecl: to depend on its ftimulating the ftomach into (Irdriger ac- tion, and thus, by the afTociation of this vifcus with the heart and arteries, preventing the torpor of any part of the fanguif* Vol. I. T t t eidui $6 SORBENTIA. Ar*. IV. t. 6. 9. crous fyflem. 1 was led to this conclufion from the following confiderations. Firft. The efFedts of arfenic given a long time internally in fmall dofes, or when ufed in larger quantities externally feem to be fimilar to thole of other great ftimuli, as of wine or alco- hol. Thefe are a bloated countenance, f welled legs, hepatic tu- mours, and dropfy, and fometimes eruptions on the fkin. The former of thefe I have feen, where arfenic has been ufed external- ly for curing the itch •, and the latter appears on evidence in the famous trial of Mils Blandy at Chelmsford, about forty years ago. Secondly. I faw an ague cured by arfenic in a child, who had in vain previoufly taken a very large quantity of bark with great regularity. And another cafe of a young officer, who had lived in temperately, and laboured under an intermittent fever, and had taken the bark repeatedly in confiderable quantities, with a grain of opium at night, and though the paroxyfms had been thrice thus for a time prevented, they recurred in about a week. On taking five drops of a faturated folution of arfenic thrice a day the paroxyfms ceafed, and returned no more, and at the fame time his appetite became much improved. Thirdly. A gentleman about fixty-five years of age had for about ten years been fubjedt to an intermittent pulfe, and to frequent palpitations of his heart. Lately the palpitations fe'emed to obferve irregular periods, but the intermiflion of eve- ry third or fourth puliation was almoft perpetual. On giving him four drops of a faturated folution of arfenic from a two- ounce phial almoft every four hours for one day, not only the palpitation did not return, but the intermiflion ceafed entirely, and did not return fo long as he took the medicine, which was three or four days. Now as when the ftomach has its action much weakened by an over-dofe of digitalis, the pulfe is liable to intermit, this evin- ces a direct fympathy between thefe parts of the fyflem ; and as I have repeatedly obferved, that when the pulfe begins to in- termit in elderly people, that an eruc~lation from the ftomach, voluntarily produced, will prevent the threatened flop of the heart ; I am induced to think, that the torpid ftate of the ftom- ach, at the inftant of the production of air occafioned by its weak action, caufed the intermiflion of the pulfe. And that arfenic in this cafe, as well as in the cafes of agues above men- tioned, produced its effects by Simulating the ftomach into more powerful action ; and that the equality of the motions of the heart was thus reftored by increafmg the excitement of the fen- forial power of aflbciation. See Sect. XXV. 17. Clafs IV. iS. Arfenic* Art. IV. 2. 7. 1. SORBENTIA. 57 Arfenic has lately been recommended in the hooping cough, tuflis convulfiva, by Mr. Simmons, furgeon of Manchefter, which he afferts to be attended with the mod falutarv effects, moderating the difeafe in a few days, and curing irgenerally in a fortnight. He has given it to children of a year old with fafe- ty, in the dofes recommended by Dr. Fowler, whofe folution he ufed, but feems to have ufed venefeclion and emetics occa- fionally, and recommends, after the folution has been omitted for a week, to repeat it, to prevent a relapfe. Annals of Med^ icine, 1797. 10. Where arfenic has been given as poifon, it may be dif- covered in the contents of the ftomach by the fmell like garlic, when a few grains of it are thrown on a red-hot iron. 2. If a few grains are placed between two plates of copper, and fub- jected to a red heat, the copper becomes whitened. 3. Dif- folve arfenic in water along with vegetable alkali, add to this a folution of blue vitriol in water, and the mixture becomes of a fine green, which gradually precipitates, as difcovered by Berg- man. 4. Where the quantity is fufficient, fome wheat may be fleeped in a folution of it, which given to fparrows or chickens will deftroy them. VII. 1 . Abforption of the matter from venereal ulcers. No ulcer can heal, unlefs the abforption from it is as great as the depofition in it. The preparations or oxydes of mercury in the cure of the venereal difeafe feem to act by their increasing the abforption of the matter in the ulcers it occafions ; and that whether they are taken into the fiomach, or applied on the fkin, or on the furface of the ulcers. And this in the fame manner as fugar of lead, or other metallic oxvdes, promote fo rapidly the healing of other ulcers by their external application ; and probably when taken internally, as ruft of iron given to children affected with fcrofulous ulcers contributes to heal them, and fo~ lutions of lead were once famous in phthills. The matter depofited in large abfceffes does not occafion hec- tic fever, till it has become oxygenated, by being expofed to the open air, or to the air through a moid membrane ; the fame feems to happen to other kinds of matter, which produce fever, or which occafion fpreading ulcers, and are thence termed con- tagious. See Clafs II 1.3. II. 1. 5. II. 1. 6. 6. This may perhaps occur from thefe matters not being generally absorbed, till they become oxygenated ; and that it is the Itimulus of the acid thus formed by their union with oxygen, which occafions their abforption into the circulation, and the fever, which they then produce. For though collections of matter, and milk, and mucus, are fometimes fuddenly abforbed during die action of emetics 5 a SORBENTI A. Art. IV. 2. 7. 2, emetics or in fea~ficknefs, they are probably eliminated from the body without entering the circulation ; that is, they are taken up by the increafed action of one lymphatic branch, and evacu- ated by the inverted action of fome other lymphatic branch, and thus carried off by ftool or urine. 2. Cut as the matter in large abfeefles is in general not ab- sorbed, till it becomes by fome means expofed to air, there is reafon to conclude, that the ftimulus of this new combination of the matter with oxygen occafions its abforption ; and that hence the abforption of matter in ulcers of all kinds, is (till more powerfully effected by the external application or internal ufe of metallic oxydes ; which are alfo acids confiding of the metal united with oxygen ; and laftly, becaufe venereal ulcers, and thofe of itch, and tinea, will not heal without fome ftimulant application ; that is, the fecretion of matter in them continues to be greater, than the abforption of it ; and the ulcers at the fame time continue to enlarge, by the contagion affecting the edges of thern ; that is, by the ftimulus of the oxygenated mat- ter ftimulated the capillary veflels in its vicinity into actions fimilar to thofe of the ulcer, which produces it. This effedt. of the oxydes of mercury occurs, whether faliva- tion attends its ufe or not. Salivation is much forwarded by external warmth, when mercury is given to promote this fecre- tion ; but as the cure of venereal complaints depends on its ab- forbent quality, the act of falivation is not necefiary or ufeful. A quarter of a grain of good corrofive fublimate twice a day will fcldom fail of curing the molt confirmed pox ; and will as feldom falivate, if the patient be kept cool. A quarter of a grain thrice a day I believe to be infallible, if it be good fub- limate. Mercury alone when fwallowed does not act beyond the in- reftines ; its active preparations are the falts formed by its union with the various acids, as mentioned in the catalogue. Its union with the vegetable acid, when triturated with manna, is faid to compole Keyfers Pill. Triturated with gum arabic it is much recommended by Plenck ; and triturated with fugar and a little effential oil, as directed in a former Edinburgh Difpenfatory, it probably forms fome of the fyrups fold as noftrums. United with fulphur it feklorn enters the circulation, as when Cinnabar, or iethiops mineral, is taken inwardly. But united villi fat and rubbed on the Ikin, it is readily abforbed. I know not whether it can be united to charcoal, nor whether it ha \\ en internally when united with animal fat ; if fix grains ty of fulphur be added to two ounces of hog's fat and Gx drachma Art. IV. 2.8. i. SORBENTIA. 59 drachms of mercury, they are fald to unite with much lefs la- bour cf trituration, than the hog's fat and mercury alone. VIII. 1. Abforptions in general are increafed by inanition j hence the ufe of evacuations in the cure of ulcers. Dr. Jurin abforbed in one night, after a day's abftinenee and exercife, eighteen ounces from the atmofphere in his chamber ; and eve- ry one mud have obferved, how foon his meets became dry, after having been moiftened by fweat, if he throws off part of the bed-clothes to cool himfelf ; which is owing to the increafed cutaneous abforption after the evacuation by previous fweat. 2. Now as opium is an univerfal flimulant, as explained in the article of Incitantia, it muft ftimulate into increafed action both the fecretory fyftem, and the abforbent one ; but after re- peated evacuation by venefect ion, and cathartics, the abforbent fyftem is already inclined to act more powerfully ; as the blood- vefTels being lefs diftended, there is lefs refi fiance to the progrefs of the abforbed fluids into them. Hence after evacuations opi- um promotes abforption, if given in fmall dofes, much more than it promotes fecretion ; and is thus eminently of fervice at the end of inflammations, as in pleurify, or peripneumony, in the dofe of four or five drops of the tincture, given before the accefs of the evening paroxyfm ; which I have feen fucceed even when the rifus fardonicus has exifted. Some convulfions may originate in the want of the abforption of fome acrid fecre- tion, which occafions pain ; hence thefe difeafes are fo much more certainly relieved by opium after venefection or other evacuations. IX. 1. Abforption is increafed by the calces or folutions of mercury, lead, zinc, copper, iron, externally applied ; and by arfenic, and by fulphur, and by the application of bitter vegeta- bles in fine powder. Thus an ointment confiding of mercury and hog's fat rubbed on the fkin cures venereal ulcers ; and ma- ny kinds of herpetic eruptions are removed by an ointment con- fiding of fixty grains of white precipitate of mercury and an ounce of hog's fat. 2. The tumours about the necks of young people are often produced by the abforption of a faline or acrid material, which has been deposited from eruptions behind the ears, owing to de- ficient abforption in the furface of the ulcer, but which on run- ning down on the fkin below becomes abforbed, and fwells the lymphatic glands of the neck •, as the variolous -matter, when inferted into the arm3 fwells the gland of the axilla. Some- times the perfpirative matter produced behind the ears becomes putrid from the want of daily warning them, and may alio caufe by its abforption the tumours cf the lymphatics of the neck. In 6o SORBENTIA. Art. IV. 2. 9. 3, In the former cafe the application of a cerate of lapis calamina- ris, or of cerufTa in dry powder, or of rags dipped in a folution of fugar of Lead, increafes the abforption in the ulcers, and pre- vents the effufion of the faline part of the fecreted material. The latter is to be prevented by cleanlinefs. After the eruptions or ulcers are healed a folution of corrofive fublimate of one grain to an ounce of water applied for fome weeks behind the ear, and amongft the roots of the hair on one fide of the head, where the mouths of the lymphatics of the neck open themfelves, frequently removes thefe tumours. 3. Linen rags nioiftened with a folution of half an ounce of fugar of lead to a pint of water applied on the eryfipelas on ana- farcous legs, which have a tendency to mortification, is more efficacious than other applications. White vitriol fix grains diflblved in one ounce of rofe water removes inflammations of the eyes after evacuation more certainly than folutions of lead. Blue vitriol two or three grains diflblved in an ounce of water cures ulcers in the mouth, and other mucous membranes, and a folution of arfenic externally applied cures the itch, but re- quires great caution in the ufe of it. See Clafs II. 1. 5. 6. A feeble old man with fwelled legs had an eryfipelas on both of them ; to one of thefe legs a line powder of Peruvian bark was applied dry, and renewed twice a day j on the other linen rags moiltened with a folution of faccharum faturni were appli- ed, and renewed twice a day ; and it was obferved, that the latter healed much fooner than the former. « As the external application of calx of lead ftimulates inflam- ed parts very violently, if it be applied too early, before the veflels are emptied by evacuations, or by the continuance of the difeafe, it is liable to increafe the inflammation, or to induce mortification, as in ophthalmy ; and in a cafe, which was re- lated to me of a perfon who much pricked his legs amongft gorfe, which, on the application of Goulard's folution of lead, mortified with extenfive floughs. But where the fyftem is pre- vioufly emptied, there is lefs refinance to the progrefs of ab- forbed fluids ; and the ftimulus of lead then increafes the ac- tion of the abforbent fyftem more than of the fecerning fyftem, and the inflamed part prefently difappears. 4. Bitter vegetables, as the Peruvian bark, quilted between two fliirts, or ftrewed in their beds, will cure the ague in chil- dren fometimes. Iron in folution, and fome bitter extract, as in the form of ink, will cure one kind of herpes called the ringworm. And I have {cen feven parts of bark in fine powder mixed with one part of cerufe, or white lead, in fine powder, applied dry .to fcrofulous ulcers, and renewed daily, with great advantage. 5. To Art. IV. 2. 9. 5- SORBENTIA, 81 5. To thefe mould be added ele&ric fparks and mocks, which promote the abforption of the veflels in inflamed eyes of fcrofulous children ; and difperfe, or bring to fuppuration, fcrof- ulous tumours about the neck. For this laft purpofe fmart fhocks mould be pafled through the tumours only, by enciofing them between two brafs knobs communicating with the external and internal coating of a charged phial. See Art. II. 2. 2. 2. X. 1. Bandages increafe abforption, if they are made to fit nicely on the part ; for which purpofe it is neceflary to fpread fome moderately adhefive plafter on the bandage, and to cut it into tails, or into (breads two inches wide ; the ends are to be wrapped over each other ; and it muft be applied when the part is leaft tumid, as in the morning before the patient rifes, if on the lower extremities. The emplaftrum de minio made to cov- er the whole of a fwelled leg in this manner, whether the fuell- ing is hard, which is ufually termed fcorbutic •, or more eafily compreffible, as in anafarca, reduces the limb in two or three days to its natural fize •, for this purpofe I have fometimes ufed carpenter's glue, mixed with one twentieth part of honey to prevent its becoming too hard, inftead of a refinous plafter j but the minium plafter of the (hops is in general to be preferred. Nothing fo much facilitates the cure of ulcers in the legs, as covering the whole limb from the toes to the knee with fuch a plafter bandage ; which increafes the power of abforption in the furface of the fore. 2. The lymph is carried along the abforbent veflels, which are replete with valves, by the intermitted preflure of the arteries in their neighbourhood. Now if the external (kin of the limb be lax, it rifes, and gives way to the prelhire of the arteries at every pulfa- tion ; and thence the lymphatic veflels are fubjecl: to the preflure of but half the arterial force. But when the external fkin is tightened by the furrounding bandage, and thence is not elevated by the arterial diaftole, the whole of this power is exerted in comprefling the lymphatic veflels^ and Carrying on the lymph al- ready abforbed ; and thence the abforbent power is fo amazing- ly increafed by bandage nicely applied. Pains are fometimes left in the flefhy parts of the thighs or arms, after the inflamma- tion is gone, in the acute rheumatifm, or after the patient is too weak for further evacuation ; in this cafe after internal abforbent medicines, as the bark, and opiates, have been ufed in vain, I have fuccefsfully applied a r3lafter-bandage, as above defcribed, fo as to compreis the pained part. Since the above was written, Mr. Bay n ton, an ingenious fur- geon of Briftol, has publilhed " A Method of Treating Ulcers of the Legs," fold by Robin fon, London. In which he endeav- ours 02 SORBENTIA. Art. IV. 2. 1 1.1- ours to bring the lips of thofe ulcers nearer together by means of flips of adhefive plafter, as above defcribed ; which feems to have been attended with great fuccefs, without confinement of the patient. See Seel. XXXIII. 3. 2. But when flips of adhefive plafter are put over a wound fo as to bring the edges of it together nearly, or quite, into contact with each other, the part is at the fame time covered, as the flips of adhefive plafter are applied, from the eye of the furgeon. I have therefore advifed two tin plates a little longer than the wound, and about half an inch broad, to be fattened to the ends of the pieces of adhefive plafter, and applied one on each lip of the wound or ulcer ; and then by a narrow flip of adhefive plaf- ter applied at each end of thefe tins, they may be drawn togeth- er, and the whole lips of the wound may be feen at the fame time by the furgeon 5 and then a comprefs of thin lead, or of lin- en, may be applied by other ftrips of plafter fo as to heal recent wounds, and even ulcers, without fcarcely any unevennefs or width of the fear. XI. 1. We (hall conclude by obferving, that the forbentia ftrengthen the whole habit by preventing the efcape of the fluid part of the fecretions out of the body, before it has given up as much nourifhmeut, as it is capable j as the liquid part of the fe- cretion of urine, fweat, faliva, and of all other fecretions, which are poured into receptacles. Hence they have been faid - to brace the body, and been called tonics, which are mechanical terms not applicable to the living bodies of animals; as explain- ed in Sect. XXXII. 3. 2. 2. A continued ufe of bitter medicines for years together, as of Portland's powder, or of the bark, is fuppoied to induce apo- plexy, or other fatal difeafes. Two cafes of this kind have fall- en under my obfervation ; the patients were both rather intem- perate in refpecl to the ufe of fermented liquors, and one of them had been previoufly fubjecl: to the gout. As I believe the gout generally originates from a topor of the liver, which, in- ftead of being fucceeded by an inflammation of it, is fucceeded by an inflammation of fome of the joints ; or by a pimpled face, which is another mode, by which the difeafe of the liver is ter- minated : I conceive, that the daily ufe of bitter medicines had in thefe patients prevented the removal of a gouty inflammation from the liver to the membranes of the joints of the extremities, or to the ikin of the face, by preventing the neceflary torpor of thefe parts previous to the inflammation of them ; in the fame manner as cold fits of fever are prevented by the fame medicines ; and, as I believe, the returns of the gout have fome times for two or three years been prevented bv them. One Astt . IV. 3. u SORBENTIA* One of thefe patients died of the apoplexy in a few hours j §uld the other of an inflammation of the liver, which I believe was called the gout, and in confequence was not treated by vein 'election, and other evacuations, Hence it appears, that the tlaily ufe of hop in our malt liquor muft add to the noxious qual- ity of the fpirit in it, when taken to excefs, and contribute I § the production of apoplexy, or inflammation of the liver, til. Catalogue of the Sorbei^tia, t Sorbentia affecting the BciriV i, Acid of vitriol, of fea-falt, lemons, floes, primus Ipi- nofa, crabs, pyrusj quince, pyrus cydoniaj opium. 2. Externally calx of zinc, of lead, or of mercury, H, Sorbentia affecting the mucous membranes. i. Juice of floes, crabs, Peruvian bark, cinchona, opium.: 2. Externally blue vitriol. * tit, Sorbentia affecting the cellular membrane* i. Peruvian bark, wormwoods, artemifia maritime, arte^ mifia abfynthium, worm-feed, artemifia faritonicumj chamomile, anthemis nobilis, tanfey, tanacetum, bog° bean, menyanthes trifoliata, centaury, gentiarta centau- rium, gentian, gentiana lu':ea, artichoke-leaves, cynara fcolymus, hop, humulus lupulus, falix eaprea, geum urbamimj datifca cannabina^ 2i Orange-peel^ cinnamon, nutmeg* rttaee:. 3. Vomits, fquill, digitalis, tobacco, 4. Bath of warm air, of ftearrn lv» Sorbentia affecling the Veins, " « . ii Water-crefs, fifymbrium nafturtitim aquaticuni, muf* tardj finapis, fcurvy-grafs, cochlearia hortenfis, hoirfe- radiihj cochlearia armoracia, cuckoo-flower, carda- mine, dog's-grafs, dandelion, leontodon, taraxacon, cellery, apium, cabbage, braffica; g. Chalybeates, bitters, and opium, after fufficitnt etctc1 Uation^ p Externally vinegar, friction, electricity, V. Sorbentia aftecYm ^ the inteitines. t. Rhubarb, rheum palmatum, oak-galls, galte querciri&j tormentilia erecra, cinquefoil, potentilla, red-rofes; UVa urfi, fimarouba. fa. Logwood, hsematoxylumi cariipechiaiium^ fucc acacia, dragon's blood, terra japonicd, mimofa catechu* |» Alum, earth of alum, Armenian bote, chalk, creta. crab'd Vf»ij L . U u U ciawf| *4 SORBENTIA. Art. IV. 3. 6. claws, chelae cancrorum, white clay, cimolia, calcined hartfhorn, cornu cervi calcinatum, bone-aihes. VI. Sorbentia affecting the liver, ftomach, and other vifcera. Ruft of iron, filings of iron, fait of fteel, fal martis, blue vitriol, white vitriol, calomel, emetic tartar, fugar of lead, white arfenic. VII. Sorbentia affecting venereal ulcers. Mercury dilTolved or corroded by the following acids : 1 . DiiTolved in vitriolic acid, called turpeth mineral, or hydrargyrus vitriolatus. 2. DiiTolved in nitrous acid, called hydrargyrus nitratus ruber. 3. DiiTolved in muriatic acid, mercurius corrofivus fub- limatus, or hydrargyrus muriatus. 4. 'Corroded by muriatic acid. Calomel. 5. Precipitated from muriatic acid, mercurius precipita- tus albus, calx hydrargyri alba. 6* Corroded by carbonic acid ? The black powder on crude mercury.. 7. Calcined, or united with oxygen. 8. United with animal fat, mercurial ointment. 9. United with fulphur. Cinnabar. 10. Partially united with fulphur. iEthiops mineral. 11. Divided by calcareous earth. Hydrargyrus cum creta. 12. Divided by vegetable mucilage, by fugar, by balfams. VIII. Sorbentia affecting the whole fyftem. Evacuations by venefection and catharfis, and then the exhibition of opium. IX. Sorbentia externally applied. 1. Solutions of mercury, lead, zinc, copper, iron, arfen- ic ; or metallic calces applied in dry powder, as ce- rufla, lapis calaminaris. 2. Bitter vegetables in decoctions and in dry powders, applied externally, as Peruvian bark, oak bark, leaves of wormwood, of tanfey, chamomile flowers or leaves. 3. Electric fparks, or (hocks. X. Bandage fpread with emplaftrum e minio, or with car- penter's glue mixed with one twentieth part of honey. XI. Portland's powder its continued ufe pernicious, and of hops in beer. Art- Art. V. i. i, INVERTENTIA. 6$ Art. V. INVERTENTIA. 1. Those things, which invert the natural order of the fuc* ceflive irritative motions, are termed invertentia. i. Emetics invert the motions of the ftomach, duodenum, and cefophagus. 2. Violent cathartics invert the motions of the lacleals, and inteftinal lymphatics. 3. Violent errhines invert the nafal lymphatics, and thofe of the frontal and maxillary finufes. And medicines producing naufea, invert the motions of the lymphatics about the fauces. 4. Medicines producing much pale urine, as a certain quan- tity of alcohol, invert the motions of the urinary abforbents ; if the dofe of alcohol is greater, it inverts the ftomach, producing the drunken ficknefs. 5. Medicines producing cold fweats, palpitation of the heart, globus hyftericus j as violent evacuations, fome poifons, fear, anxiety, act by inverting the natural order of the vafcular motions. II. Observations on the Invertentia. I. 1. The action of vomiting feems originally to have been occafioned by difagreeable fenfation from the detention or acri- mony of the aliment •, in the fame manner as when any difguft- ful material is taken into the mouth, as a bitter drug, and is re- jetted by the retrograde motions of the tongue and lips ; as explained in Clafs IV. 1. 1. 2. and mentioned in Sect.. XXXV. 1.3. Or the difagreeable fenfation may thus excite the power of volition, which may alfo contribute to the retrograde actions of the ftomach and cefophagus, as when cows bring up the con- tents of their firft ftomach to remafticate it. To either of thefe is to be attributed the action of mild emetics, which foon ceafe to operate, and leave the ftomach ftronger, or more irritable, after their operation ; owing to the accumulation of the fenfo- rial power of irritation during its torpid or inverted action. Such appears to be the operation of ipecacuanha, or of antimo- nium tartarizatum, in fmall dofes. 2.' But there is reafon to believe, that the ftronger emetics, as digitalis, firft ftimulate the abforbent veflels of the ftomach into greater action -, and that the inverted motions of thefe ab- forbents next occur, pouring the lymph, lately taken up, or ob- tained m t«V£RTENTIA, Art, V, ;, |. ^ tained from o.ther lymphatic branches, into the ftomach ; the quantity of which in fome (lifeafes, as in the cholera morbus, is inconceivable. This inverted motion, firft of the abforbents ol the ftomach, and afterwards of the ftomach itfelf, feems to origK jiatc from the exhauftioii or debility, which fucceeds the un«* natural degree of acllon, into which they had been previoufly {Simulated. An unufual defect of ftimulus, as of food without fpice or wine in the ftomachs of thofe, who have been much sccuftcmed to fpicc or wine, w'i\\ induce ficknefs or vomiting ; in this cafe the defective energy of the ftomach is owing to defecl: of accuftomed ftimulus ; while the action of vomiting- £rom digitalis is owing to a deficiency of fenforial power, which is previoufly exhaufted by the excefs of its ftimulus, $ee Se&. XXXV, 1.3. and Clafs IV, 1. 1. 2. For (irfl:, no increafe of heat arifes from this action of vomi^* ing ; which always occurs, when the fecerning fyfteni is ftimu- lated into action. Secondly, the motions of the abforbent vef- fcls are as liable to inverfion as the ftomach itfelf ; which laft, with the cefophagus, may be confidered as the abforbent mouth and belly of that great gland, the inteftinal canal. Thirdly^ the clafs of iorbentia, as bitters and metallic falts, given in large doies, become invcrtentia, and vomit, or purge. And laftly, the (xcknefs and vomiting induced by large potations of wine^ or opium, does not occur till next day in fomc people, in none till fome time after their ingurgitation. And tincture of digi- talis in the dofe of 30 or 60 drops, though applied in folution, ist a considerable time before it produces its effect •, though vomiting ji inftantaneoufly induced by a nafeous idea, or a naufeous taftt? in the mouth, At the fame time there feem to be fome mate- rials which can irrmediaely ftimulate the ftomach into fuch pow- erful action, as to he immediately fucceeded by paralyfis of ifa and confequent continued fever, or immediate death ; and thl without exciting fenfation, that is, without our perceiving it. Qf thefc are the contagious matter of fome fevers fwallowed with the faliva, and probably a few grains of arfenic taken in fo lution. See Suppl, I. 8- 8- Art. IV. 2. 6. 9, 3. Some blanches of the lymphatic fyftem become inverted hy their fympaihy with other branches, which are only ftimu- bted into too violent abforption. Thus, when the ftomach and| duodenum are much ftimulated by alcohol, by nitre, or by worms, in fome perfbns the urinary lymphatics have their mo- tion inverted, and pour that material into the bladder, which is, orbed from the inteftines. Hence the drunken diabetes is produced ; and hence chyle is feen in the urine in worm yaf< Whci\ Art. V* a, i . 4. INVERTENTI A, i j When on the contrary fome branches of the abforbent fyttems have their motions inverted in conference of the previous ex- haustion of their fenforial power by any violent ilimulus, other branches of it have their abforbent power greatly increafed, Hence continued vomiting, or violent cathartics, produce great abforption from the cellular membrane in cafes of dropfy 5 and the fluids thus abforbed are poured into the ftomach and intcl* tines' by the inverted motions of the lafteals and lymphatics, See ge&, XXIX, 4, and 5. 4. The quantity of the dofe of an emetic is not of fo great confequence as of other medicines, as the greater!: part of it U rejected with the firft effort, AU emetics are (aid to act with greater certainty when given in a morning, if an opiate had been given the night before. For the fenforial power of irrita* tion of the ftomach had thus been in fome meafure. previoufly exhaufted by the ftimulus of the opium, which thus facilitates the action of the emetic ; and which, when the dole of opium has been large, is frequently followed on the next day by (pan* faneous fjcknefs and vomitings, as after violent intoxication. Ipecacuanha is the moil certain in its efTecl: from five grains to thirty j white vitriol is the moft expeditious in its efffecfc, from twenty grains to thirty diffolved in warm water j butet* |c tartar,, antirnonium tartarizatum, from one grain to four to fane people, and from thence to twenty to in fane patients, will qnfwer moil of the ufeful purpofes of emetics j but nothing equals the digitalis purpurea for the purpofe qf absorbing w ., from the cellular membrane in the anafarca pu!monum3 or 'hy- drops pectoris,. See Art, II. 3, 7, II. Violent cathartics. 1, "Where violent cithartics are re* quired, as in dropfies, the fquill in dried powder mads into (mail pills of a grain, or a grain and * half* one to be given ery hour till they operate brifkly, is very efficacious ; or half a grain of emetic tartar di/Folved in an ounce- of peppermint-Wat*: , and given every hour, till it operates, Scammony, and other ftrqng purges, are liable to produce hypercatharfis, if they not nicely prepared, and accurately w rl, 2nd are * dangerous in common practice. Gamboge is uncertain in it? effects, it has otherwife the good propertv of f being taftele-fs } on that account fome preparation of it might be uf< r clrlL dren, by which its dofe could be afeertained, and Its eflfe N - dered more uniform, 2. In inflammations of the bowels with coj'lhp.'.tjon oalom. glyen in a dole from ten to twenty grains, after dnr ven ioUi }g rnoft efficacious j and if made into very fma.ll pills i feje t§ 1 be reje^ed by vomiting which geiietalty attCl cai 68 1NVERTENTIA. Art. V. 2. 3. u cafes. When this fails, a grain of aloes every hour will find its way, if the bowel is not deftroyed ; and fometimes, I believe, if it be, when the mortification is not extenfive. If the vomiting continues after the pain ceafes, and efpecially if the bowelg be- come tumid with air, which founds on being ftruck with the finger, thefe patients feldom recover. Opiates given along with the cathartics I believe to be frequently injurious in inflam- mation of the bowels, though they may thus be given with ad- vantage in the faturnine colic ; the pain and conftipationTin which difeafe are owing to torpor or inactivity, and not to too great aclion. See Clafs I. 2. 4. 8. III. Violent errhines and fialagogues. 1. Turpeth mineral in the quantity of one grain mixed with ten grains of fugar an- fwers every purpofc to be expected from errhines. Their oper- ation is by inverting the motions of the lymphatics of the mem- brane, which lines the noftrils, and the caverns of the forehead and cheeks \ and may thence poflibly be of fervice in the hydro- cephalus internus. Some other violent errhines, as the powder of white hellebore, or Cayenne pepper, diluted with fome lefs acrid powder, are faid to cure fome cold -or nervous head-achs ;' which may be effect- ed by inflaming the noftrils, and thus introducing the fenforial power of fenfation, as well as increafmg that of irritation ; and thus to produce violent action of the membranes of the noftrils, and of the frontal and maxillary finufes, which may by aflbcia- tion excite into action the torpid membranes, which occafion tl headach. They may be ufed on the fame account in amauro- fis and in deafnefs. 2. A copious falivation without any increafe of heat often at- tends hyiteric difeafes^ and fevers with debility, owing to an in- verfion of the lymphatics of the mouth, fee Clafs I. 1. 2. 6. The fame occurs in the naufea, which precedes vomiting ; and is alfo excitable by difagreeable taftes, as by (quills, or by naufeous fmells, or by naufeous ideas. Thefe are very fimilar to the oc- cafional difcharge of a thin fluid from the noftrils of fome peo- ple, which recurs at certain periods, and differs from defective abforption. IV. Violent diuretics. 1. If nitre be given from a dram to half an ounce in a morning at repeated draughts, the patient becomes fickifh, and much pale water is thrown into the blad- der by the inverted action of the urinary lymphatics. Hence the abforption in ulcers is increafed and the cure forwarded, as ob- served by Dr. Rowley. 2. Cantharides taken inwardly fo ftimulate the neck of the bladder as to increafe the difcharge of mucus, which appears in the .Art. V. 2. 4. 3. INVERTENTIA* 69 the urine •, but I once faw a large dofe taken by miftake, not left than half an ounce or an ounce of the tincture, by which I fup- pofe the urinary lymphatics were thrown into violent inverted motions, for the patient drank repeated draughts of fubtepid water to the quantity of a gallon or two in a few hours •, and during the greater! part of that time he was not I believe two entire minutes together without making water. A little blood was feen in his water the next day, and a forenefs continued a day longer without any other inconvenience. , 3. The decoction of foxglove mould alfo be mentioned here, as great effufions of urine frequently follow its exhibition. See Art. IV. 2. 3. 7. And an infufion or tincture of tobacco a* recommended by Dr. Fowler of York. 4. Alcohol j and opium, if taken fo as to induce flight intoxi- ication, and the body be kept cool, and much diluting liquids taken along with them, have fimilar effect in producing for a: time a greater flow of urine, as moft intemperate drinkers mull occafionally have obferved. This circumftance feems to have introduced the ufe of gin, and other vinous fpirits, as a diuretic, unfortunately in the gravel, amongft ignorant people ; which difeafe is generally produced by fermented or fpirituous liquors, and always increafed by them. 5. Fear and anxiety are well known to produce a great fre* . quency of making water. A perfon who believed he had made a bad purchafe concerning an eftate, told me, that he made five or fix pints of water during a fleeplefs night, which fucceeded his bargain ; and it is ufual, where young men are waiting in an antiroom to be examined for college preferment, to fee the chamber-pot often wanted. V. Cold fweats about the head, neck, and arms, frequently attend thofe, whofe lungs are opprefTed, as in fome dropfies and safthma. A cold fweat is alfo frequently the harbinger of death* Thefe are from the inverted motions of the cutaneous lymphat* *c branches of thofe parts. III. Catalogue of Invertentia. I. Emetics, ipecacuanha, emetic tartar, antimonium tartari- fatum, fquill, fcilla maritima, carduus benedictus, cni» cus acarna, chamomile, anthemis nobilis, white vitriol, vitriolum zinci, foxglove, digitalis purpurea, clyfteri of tobacco. II. Violent cathartics, emetic tartar* fquill, buckthorn, rham- nus catharticus, fcammonium, convolvulus fcammo- nia, 1* MVfc&TENTiA, Art. VLui; ilia, gamboge, elateriiirii, colocynth, cUGiimis eolocyri- this, Veratrum. lit Violent errhines arid fiaiagogiies, turpeth mineral, hydra* gyrus vrtriolatus, afarum europium, eUphorbium, ear)* in tlm, veratrum, riaufeous fmells, naufeous ideas* IV» Violent diuretics, nitre, fqutll, feneka, caritharides, akdfl hoi, foxglove, tobacco, anxiety* V» Cold fudoriiks, poifbns, fear, approaehirig dedtrh Art. Vi» REVERT£NTfA» 1. Those THiNcJs, which reftore the natufal order" of the iii-s Verted irritative motions, are termed Revertentia* 1 » As mufk, caftor, afafoetida, valerian, eflential oils. 2. Externally the vapour of burnt feathers, of Volatile faks* Of oils, blifters, finapifms. Thefe reclaim the inverted motions without iricrdafiflg the heat of the body above its natural ftate, if given in their pfopeir dofes, as in the globus hystericus, and palpitation of the heart* The incitantia reVert thefe morbid motions more certainly, ay opium arid alcohol J and reftore the natural heat more ; but if they induce any degree of intoxication, they are fuceeeded by Ability, when their ftimiilus ceafes. It. Observations otf the Revertent iAi I. 1. The hyfteric difeafe is attended with inverted motions feebly exerted of the oefophagUs, inteftinal canal and lymphat- ics of thebjadder. Hence the borborigmi,or rumbling of the bow- els, owing to their fluid contents defcending as the air beneath afcends. The globus hyftericus confifts in the retrograde mo* tion of the cefophagus, and the great flow of urine from that of the lymphatics fpread on the neck of the bladder ; arid a copious falivation fometimes happens to thefe patients from the inverfiort of the lymphatics of the mouth ; and palpitation of the heart owing to weak or incipient inverfion of its motions i and fyn- cope, when this occurs in its greateft degree. Thefe hyfteric affections are not necefTarily attended with p-in ; though it fometimes happens, that pains, which originate fro-*- Art. V. 2.2.1. REVERTENTIA* 7 i from quiefcence, afflict thefe patients, as the hemicrania, which has erroneoufly been termed the clavus hystericus ; but which is owing folely to the inaction of the membranes of that part, like the pains attending the cold fits of intermittents, and which fre- quently returns like them at very regular periods of time. Many of the above fymptoms are relieved by mufk, caftors the foetid gums, valerian, oleum animale, oil of amber, which act in the ufual dofe without heating the body. The pains, which fometimes attend thefe conftitutions, are relieved by the fecernentia, as eflential oils in common tooth-ach, and ballam of Peru, in the flatulent colic. But the incitantia., as opium, or vinous fpirit, reclaim thefe morbid inverted motions with more certainty than the fcetids ; and remove the pains which attend thefe conftitutions, with more certainty than the fecernentia 3 but if given in large dofes, a debility and return of. the hyfteric fymptoms occurs, when the effect of the opium or alcohol ceafes. Opiates and fcetids joined feem belt to anfwer the purpofe of alleviating the prefent fymptoms j and the forbentia, by ftimu- lating the lymphatics and lacleals into continued adf ion, prevent a relapfe of their inverfion, as Peruvian bark, and the ruft of iron. See Clafs I. 3. I. 10. II. Vomiting confifts in the inverted order of the motions of the ftomach, and cefophagus ; and is alfo attended with the inverted motions of a part of the duodenum, when bile is eject- ed ; and of the lymphatics of the ftomach and fauces, when naufea attends, and when much lymph is evacuated. Perma- nent vomiting is for a time relieved by the incitantia, as opium or alcohol •, but is liable to return when their aclion ceafes. A blifter on the back, or on the ftomach, is more efficacious for rc- ftraining vomiting by their ftimulating into action the external Ikin, and by lympathy affecting the membranes of the ftomach. In fome fevers attended with inceffant vomiting Sydenham ad- vifed the patient to put his head under the bed-clothes, till a fweat appeared on the fkin, as explained in Clafs IV. 1. 1. 3, In chronical vomiting I have obferved crude mercury of good effecl: in the dofe of half an ounce twice a day. The vomitings, or vain efforts to vomit, which fometimes attend hyfteric or ep- ileptic patients, are frequently inftantly relieved for a time by applying flour of muftard-feed and water to the fmall of the leg ; and removing it, as foon as the pain becomes considerable If finapifms lie on too long, efpecially in paralytic cafes, they are liable to produce troublefome ulcers. A plalter or cataplafpij with opium and camphor on the region of the ftomach, will fometimes revert its retrogade motions. III. Violent cathadis, as in diarrhoea or dyfentcry, h aftend- Vol- I. W w w tui 7a REVERTEtfTIA. Art. VI. 2. 4. u cd witli inverted motions of the lymphatics of the interlines, and is generally owing to fome ftimulating material. This is coun- teracted by plenty of mucilaginous liquids, as folutions of gum arabic, or fmall chicken broth, to wafli away or dilute the ftim- ulating material, which caufes the difeafe. And then by the ufe of the inteftinal forbentia, Art. IV. 2. 5. as rhubarb, decoction of logwood, calcined hartfhorn, Armenian bole ; and laftly, by the incitantia, as opium. IV. The diabcetes confifts in the inverted motions of the urinary lymphatics, which is generally I fuppofe owing to the too great action of fome other branch of the abforbent fyftem. The urinary branch mould be ftimulated by cantharides, turpen- tine, refm, (which when taken in larger dofes may poflibly excite it into inverted action), by the forbentia and opium. The intef- tinal lymphatics fhould be rendered lefs active by torpentia, as calcareous earth, earth of alum •, and thofe of the fkin by oil externally applied over the whole body ; and by the warm- bath, which (hould be of ninety-fix or ninety-eight degrees of heat, and the patient fhould (it in it every day for half an hour. V. Inverted motions of the inteftinal canal with all the lymph- atics, which open into it, conftitute the ileus, or iliac paflion ; in which difeafe it fometimes happens, that clyfters are returned by the mouth. After venefection from ten grains to twenty of calomel made into very fmall pills ; if thefe be rejected, a grain of aloe every hour 5 a blifter, crude mercury j warm-bath ; if a clvfter of iced water ? Many other inverted motions of different parts of the fyftem are defcribed in Clafs I. 3. and which are to be treated in a man- ner fimilar to thofe above defcribed. It muft be noted, that the medicines mentioned under number one in the catalogue of revertentia are the true articles belonging to this clafs of medi- cines. Thofe enumerated in the other four divifions are chiefly fuch things as tend to remove the ftimulating caufes, which have induced the inverfion of the motions of the part, as acrimo- nious contents, or inflammation, of the bowels in diarrhoea, dia- betes or in ileus. But it is probable after thefe remote caufes are deftroyed, that the fetid gums, mufk, caftor, and balfams, might be given with advantage in all thefe cafes. III. Catalogue of Revertentia. I. Inverted motions, which attend the hyfteric difeafe, are re- claimed, 1. By mufk, caftor. 2. By afafcetida, galba- nam, fagapenum, ammoniacum, valerian. 3. Eflential oils of cinnamon, nutmeg, cloves, inf ufion of penny-roy- al, Art. VII. i.i. TORPENTIA. n al, mentha pulegium, peppermint, mentha piperita, ether, camphor. 4. Spirit of hartfhom, oleum animale, fponge burnt to charcoal, black fnuffs of candles, which confift principally of animal charcoal, wood-foot, oil of amber. 5. The incitantia, as opium, alcohol, vinegar. 6. Ex- ternally the fmoke of burnt feathers, oil of amber, vola- tile fait applied to the noftrils, blifters, finapifms. II. Inverted motions of the ftomach are reclaimed by opium, alcohol, blifters, crude mercury, finapifms, camphor and opium externally, clyfters with afafcetida. III. Inverted motions of the inteftinal lymphatics are reclaim- ed by mucilaginous diluents, and by inteftinal forben- tia, as rhubarb, logwood, calcined hartlhorn, Armenian bole ; and laftly by incitantia, as opium. IV. Inverted motions of the urinary lymphatics are reclaim- ed by cantharides, turpentine, refin, the forbentia, and opium, with calcareous earth of alum, by oil externally, warm-bath. V. Inverted motions of the inteftinal canal are reclaimed by calomel, aloe, crude mercury, blifters, warm-bath, clyf- ters with afafcetida, clyfters of iced water ? or of fpring water further cooled by fait diflblved in water contained in an exterior vefTel ? Where there exifts an introfuf- ception of the bowel in children, could the patient be held up for a time by the feet with his head downwards, or be laid with his body on an inclined plane with his head downwards, and crude mercury be injected as a clyfter to the quantity of two or three pounds ? Art. VII. TORPENTIA. I. Those things, which diminifh the exertion of the irrita- tive motions, are termed torpentia. 1. As mucus, mucilage, water, bland oils, and whatever poflefles lefs ftimulus than our ufual food. Diminution of heat, light, found, oxygen, and of all other ftimuli ; venefeclion, nau- fea, and anxiety. 2. Thofe things which chemically deftroy acrimony, as calca- reous earth, foap, tin, alkalies, in cardialgia ; or which prevent chemical 74 TORPENTIA. Art. VII. 2. 1. 1, chemical acrimony, as acid of vitriol in cardialgia, which pre- vents the fermentation of the aliment in the ftomach, and its confequent acidity. Secondly, which deftroy worms, as calo- mel, iron filings or ruft of iron, in the round worms ; or amal- gama of quickfilver and tin, or tin in very large dofes, in the tape-worms. Will ether in clyfters deftroy afcarides ? Thirdly, by chemically deftroying extraneous bodies, as cauftic alkali, lime, mild alkali in the ftone. Fourthly, thofe things which lu- bricate the vefTels, along which extraneous bodies Hide, as oil in the ftone in the urethra, and to expedite the expectoration of hardened mucus ; or which leffen the friclion of the contents in the inteftinal canal in dyfentery or aphtha, as calcined hartf- horn, clayj Armenian bole, chalk, bone-afhes. Fifthly, fuch things as foften or extend the cuticle over tumors, or phleg- mons, as warm water, poultices, fomentations, or by confining rhe perfpfrable matter on the part by cabbage-leaves, oil, fat3 bee's- wax, pi afters, oiled iilk, externally applied. Thefe decreafe the natural heat and remove pains occafioned by excefs of irritative motions. II. Observations on the Torpentia. I. As the torpentia confift of fuch materials as are lefs ftim- ulating than our ufual diet, it is evident, that where this clafs of medicines is ufed, fome regard muft be had to the ufual manner of living of the patient both in refpect to quantity and quality. Hence wounds in thofe, who have been accuftomed to the ulc of much wine, are very liable to mortify, unlefs the ufual pota- tion of wine be allowed the patient. And in thefe habits I have feen a delirium in a fever cured almoft immediately by wine $ which was occafioned by the too mild regimen directed by the attendants. On the contrary in great inflammation, the fub- duciion of food, and of fpirituous drink, contributes much to the cure of the difeafe. As by thefe means both the ftimulus from diftention of the veiTels, as well as that from the acrimony of the fluids, is decreafed •, but in both thefe refpecls the previous habits of diet of the patients muft be attended to. Thus if tea be made ftronger, than the patient has ufually drunk it, it be- longs to the article forbentia 5 if weaker, it belongs to the tor- pentia. II. 1. Water in a quantity greater than ufual diminifhes the aclion of the fyftem not only by diluting our fluids, and thence leflening their ftimulus, but by lubricating the folids ; for not only p&its of our folids have their fliding over each other facili- tated by the interpofition of aqueous particles 5 but the particles of Art. VII. 2,3.1. TORPENTIA. 75 of mucaginous or faccharine folutions Aide eafier over each oth- er by being mixed with a greater portion of water, and thence flimulate the veflels lefs» At the fame time it muft be obferved, that the particles of water themfelves, and of animal gluten difiblved in water, as the glue ufed by carpenters, flide eafier over each other by an additional quantity of the fluid matter of heat. Thefe two fluids of heat and of water may be efteemed the univerfal folvents or lubricants in refoect, to animal bodies, and thus facilitate the circulation, and the fecretion of the various glands. At the fame time it is poflible, that thefe two fluids may occaiionally aflume an aerial form, as in the cavity of the chefl, and by comprefling the lungs may caufe one kind of afthma, which is relieved by breathing colder air. An increas- ed quantity of heal by adding ftimulus to every part of the'fyf- tem belongs to the article Incitantia. III. 1. The application of cold to the fkin, which is only another expreilion for the diminution of the degree of heat we are accuftomed to, benumbs the cutaneous abforbents into inac- tion ; and by Sympathy the urinary and inteftinal abforbents be- come alfo quieicent. The fecerning veflels continuing their ac- tion fomewhat ionger, from the warmth of the blood. Hence the ufual fecretions are poured into the bladder and interlines, and no abforption is retaken from them. Hence fprinkling the fkin with cold water increafes the quantity of urine, which is pale \ and of (tool, which is fluid ; thefe have erroneoufly been afcribed to increafed fecretion, or to obflrutled perfpiration. The thin difcharge from the noflrils of fome people in cold weather is owing to the torpid ftate of the abforbent veflels of the membrana fchneideriana, which as above are benumbed fooner than tliofe, which perform the fecretion of the mucus. The quick anhelation, and palpitation of the heart, of thofe, who are immerfed in cold water, depends on the quiefcence of the external abforbent veflels and capillaries. Hence the cuta- neous circulation is diminilhed, and 1>y affbeiation an almolt univerfal torpor of the fyflem is induced ; thence the heart be- comes incapable to pufh forwards its blood through all the inac- tive capillaries and glands ; and as the terminating veflels of the pulmonary artery fufler a fimilar inaction by affbeiation, the blood is with difficulty pufhed through the lungs. Some have imagined, that a fpafmodic conflricl:ion of the Smaller veflels took place,, and have thus accounted for their fl fiance to the force of the heart. But there feems no nece< to introduce this imaginary fpafm 5 fince thofe, who are con- yerfant in injecting bodies, find it neceflary nrft to put them into «6 TORPEOTIA. Art. VII. 2. 3. 1. into warm water to take away the ftiffnefs of the cold dead vef* fels ; which become inflexible like the other mufcles of dead animals, and prevent the injected fluid from paffing. Before the improved knowledge of chemiftry, and of natural philofophy, and of the laws of organic life, fome writers have fpoken of cold as a ftimulus to the fyftem, inftead of fpeaking of it as a diminution of the ftimulus of heat. But the immedi- ate confequence of ftimulus is the exertion of the ftimulated fibres ; now an increafed application of heat is followed by an increafed action of the fibres expofed to it ; but an increafed application of cold is followed by a decreafed action of the fibres expofed to it ; as appears by the rednefs of our hands when warmed by the fire, and the palenefs of them, when they have been a while covered with fnow. A painful fenfation fucceeds the defect: as well as the excefs of the ftimulus of heat, as mentioned in Vol. I. Sect. IV. 5. and the voluntary exertions of the fubcutaneous mufcles called fhuddering, are excited to relieve the pain occafioned by the tor- por of the fibres expofed to cold j and thofe of the mufcles fubfervient to refpiration are voluntarily excited in fcreaming to relieve the pain occafioned by heat, which may have occafioned the error above mentioned. Others have fpoken of a fedative quality of cold, which is cer- tainly an unphilofophical expreflion •, as a fedative power, if it has any diilinct meaning, fhould exprefs a power of diminifhing any unnatural or excefiive motions of the fyftem ; but the ap- plication of cold diminifhes the activity of the fibres in general, which may previoufly be lefs than natural, as well as greater. All the fame fymptoms occur in the cold fits of intermit- xents ; in thefe the coldnefs and palenefs of the fkin with thirft evince the diminution of cutaneous abforption ; and the drynefs of ulcers, and fmall fecretion of urine, evince the torpor of the fecerning fyftem ; and the anhelation, and coldnefs of the breath, mew the terminations of the pulmonary artery to be likewife affected with torpor. After thefe veiTels of the whole furface of the body both ab- forbent and fecretory have been for a time torpid by the appli- cation of cold water i and all the internal fecerning and abforb- cnt ones have been made torpid from their aflbciation with the external j as foon as their ufual ftimulus of warmth is renewed, they are thrown into more than their ufual energy of action ; as the hands become hot and painful on approaching the fire after having been immerfed fome time in fnow. Hence the face becomes of a red colour in a cold day on turning from the wind, Art. VII. 2. 3. 2. TORPENTIA. ;r wind, and the infenfible perfpiration increafed by repeatedly go* ing into frofty air, but not continuing in it too long at a time. 2. When by the too gteat warmth of a room or of clothes the fecretion or perfpirable matter is much increafed, the ftrength of the patient is muchexhaufted by this unnecefTary exertion of the capillary fyftem, and thence of the whole fecerning and ar- terial fyftem by afTbciation. The diminution of external heat immediately induces a torpor or quiefcence of thefe unnecefTary exertions, and the patient inftantly feels himfelf ftrengthened, and exhilarated , the animal power, which was thus wafted in vain, being now applied to more ufeful purpofes. Thus when the limbs on one fide are difabled by a (Iroke of the pally, thofe of the other fide are perpetually in motion. And hence all people bear riding and other exercifes bed in cold weather. Patients in fevers, where the fkin is hot, are immediately ftrengthened by cold air ; which is therefore of great ufe in fe- vers attended with debility and heat ; but may perhaps be of temporary difTervice, if too haflily applied in fome fituations of fevers attended with internal topical inflammation, as in perip- neumony or pleurify, where the arterial ftrength is too great al- ready, and the increafed action of the external capillaries being deftroyed by the cold, the action of the internal inflamed part may be fuddenly increafed, unlefs venefection and other evacu- ations are applied at the fame time. Yet in moft cafes the ap- plication of cold is neverthelefs lalutary, as by decreafing the heat of the particles of blood in the cutaneous vefTels, the ftim- ulus of them, and the diftention of the vefTels becomes confider- ably lefTened. In external inflammations, as the fmall-pox, and perhaps the gout and rheumatifm, the application of cold air mult be of great fervice by decreafing the action of the inflamed fkin, though the contrary is too frequently the practice in thofe difeafes. It muft be obferved, that for all thefe purpofes the ap- plication of it mould be continued a long time, otherwife an in- creafed exertion follows the temporary torpor, before the difeafe is deftroyed. The topical application of cold to relieve inflammatory pains, or to deftroy the too great action of the vefTels, may be ufed with great advantage. In local inflammations, as in the pleuri- fy, or ophthalmia, or in local pains from the ftimulus of an ex- traneous body, as in gravel defcending along the ureter, the ap- plication of cold on or near the affected part may be ufed with falutary effect, as by prefling on the part a bladder full of cold water with fait difTolving in it; or by the evaporation of eth^r on it ; which may render the vefTels torpid or inactive. ' Bui d application of cold to the whole fkin might increaie the a&ioii 7* TORPENTIA. Art. VII. 2. 3. 4, of tlic inflamed vefiels by diminiftiing that of the fkin and lungs, and thus accumulating a greater quantity of fenforial power ; and this efpecially if it was applied previous to evacuations by the lancet or by cathartics. I am informed that an ingenious and eminent furgeon in Shropshire, when he was himfelf affected with gravel in the ure- ter, attended with exceflive and continued pain, found inftanta- neous relief frequently in a day by applying on the painful part" a bag of (now or pounded ice, and fuffering it to difiblve. And in the Memoirs of the Medical Society of London, Vol. V. Mr. Parkinfon of Leicefter applies cold ingenioufly to burns, and to inflammations of the eyes, by covering the part with a bladder of the greater! tenuity, which is kept perpetually moiftened for many hours, (perhaps 24 or 36) by alcohol or highly rectified fpirit of wine. In ophthalmia the eyelids were thus covered with thin bladder, and rectified fpirit of wine was applied by means of a fponge to the bladder for feme hours •, which Succeed- ed, after fatumine lotions had been ufed in vain, and deftroyed the inflammation, as foon as two ounces of alcohol had been confumed. Perhaps ether by its quicker evaporation might be more fpeedily effectual ? or mow or ice thawed more haftily by the addition of acid of nitre ? 3. After immerfion in cold water or in cold air the whole fyftem becomes more excitable by the natural degree of ftimu- lus, as appears from the fubfequent glow on the ikin of people otherwise pale ; and even by a degree of ftimulus lefs than natur- al, as appears by their becoming warm in a (hort time during their continuance in a bath, of about 80 degrees of heat, as in Buxton bath. See Sect. XII. 2. I. XXXII. 3. 3. This increafed exertion happens to the abforbent vefTels more particularly, as they are flrft and mod affected by thefe tempo- rary diminutions of heat ; and hence like the medicines, which promote abforption, the cold bath contributes to ftrengthen the conftitution, that is to increafe its irritability j for the difeafes attended with weaknefs, as nervous fevers and hyfteric difeafes, are ihewn in Sect. XXXII. 2. 1 . to proceed from a want of ir- ritability, not from an excefs of it. Hence the digeftion is greater in frofty weather, and the quantity of perfpiration. For thefc purpofes the application of cold mull not be continued too long. For in riding a journey in cold weather, when the feet are long kept too cold, the digeftion is impaired, and cardialgia produced. 4. If the diminution of external heat be too great, produced too haflily, or continued too long, the torpor of the fyftem ei- ther becomes fo great, that tiie animal ceafes to live > or fo grc'^t Art. VII. 2. 4. TORPENTIA. 79 great an energy of motion or orgafm of the veflels fucceeds, as to produce fever or inflammation. This mod frequently hap- pens after the body has been temporarily heated by exercife, warm rooms, anger, or intemperance. Hence colds are produ- ced in the external air by refting after exercife, or by drinking cold- water. See Glafs I. 2. 2. 1. Frequent cold immerfions harden or invigorate the conftitu- tion, which they efFecT: by habituating the body to bear a dimi- nution of heat on its furface without being thrown into fuch. extenfive torpor or quiefcence by the confent of the veflels of the fkin with the pulmonary and glandular fyftem ; as thofe experience, who frequently ufe the cold bath. At firft they have great anhelation and palpitation of heart at their ingrefs into cold water ; but by the habit of a few weeks they are able to bear this diminution of heat with little or no inconvenience ; for the power of volition has fome influence over the mufcles fubfervient to refpiration, and by its counter efforts gradually prevents the quick breathing, and diminifhes the aflbciations of the pulmonary veflels with the cutaneous ones. And thus though the fame quantity of heat is fubducled from the fkin, yet the torpor of the pulmonary veflels and internal glands does not follow. Hence during cold immerfion lefs fenforial power is ac- cumulated, and, in confequence, lefs exertion of it fucceeds on emerging from the bath. Whence fuch people are efteemed hardy, and bear the common variations of atmofpheric temper- ature without inconvenience. See Seel:. XXXII. 3. 2. IV. Venefeciion has a juft title to be claffed amongft the torpentia in cafes of fever with arterial ftrength, known by the fulnefs and hardnefs of the pulie. In thefe cafes the heat be- comes lefs by its ufe, and all exuberant fecretions, as of bile or fweat, are diminifhed, and room is made in the blood-veflels for the abforption of mild fluids ; and hence the abforption alfo of new veflels, or extravafated fluids, the produce of inflam- mation, is promoted. Hence venefeclion is properly clafTed amongft the forbentia, as like other evacuations it promotes gen- eral abforption, reftrains haemorrhages, and cures thofe pains, which originate from the too great adlion of the fecerning vef- fels, or from the torpor of the abforbents. I have more than once been witnefs to the fudden removal of nervous head-achs by venefeclion, though the patient was already exhaufted, pale, and feeble ; and to iis great ufe in convulfions and madnefs, whether the patient was ftrong or weak ; which difeafes are the confequence of nervous pains ; and to its flopping long debili- tating haemorrhages from the uterus, when other means had been in vain eflayed. In inflammatory pains> and iniiammato- Vol. I. X x x ry 8o TORPENTIA, Art. VII. 2i 5 ry hemorrhages, every one juftly applies to it, as the certain and •nly cure. V. When the circulation is carried on too violently, as in inflammatory fevers, thofe medicines, which invert the motions of foine parts of the fyftem, retard the motions of fome other parts, which are suTociated with them. Hence fmall dofes of emetic tartar, and ipecacuanha, and large dofes of nitre, by pro- ducing naufea debilitate and leffen the energy of the circulation, •and are thence ufeful in inflammatory difeafes. It muft be add- ed, that it nitre be fwallowed in powder, or foon after it is dif- folved, it contributes to leiTen the circulation by the cold it gen- erates, like ice-water, or the external application of cold air. VI. The refpiration of air mixed with a greater proportion of azote than is found in the common-atmofphere, or of air mix- ed with hydrogen, or with carbonic acid gas, fo that the quanti- ty of oxygen might be lefs than ufual, would probably act: in cafes of inflammation with great advantage. In confumptions this might be mod conveniently and effectually applied, if a phthifical patient could refide day and night in a porter or ale brewery, where great quantities of thofe liquors were perpetu- ally fermenting in vats or open barrels ; or in fome great manu- factory of wines from raifms or from fugar. Externally the application of carbonic acid gas to cancers and other ulcers inltead of atmofpheric air may prevent their enlargement, by preventing the union of oxygen with the mat- ter, and thus producing a new contagious animal acid. III. Catalogue of Torpentia. 1. Venefeclion. Arteriotomy. 2. Cold water, cold air, refpiration of air with lefs oxygen. j. Vegetable mucilages. a. Seeds.— Barley, oats, rice, young peas, flax, cucumber, melon, &c. b. Gums.— Arabic, tragacanth, Senegal, of cherry-trees. 6\ Roots.— Turnip, potatoe, althea, orchis, fnow-drop. d. Herbs.— Spinach, brocoli, mercury. 4. Vegetable acids, lemon, orange, currants, goofeberries, apples, grape, &c. g. Animal mucus, hartmorn jelly, veal broth, chicken water, oil r* fat ? cream ? 6. Mineral acids, of vitriol, nitre, fea-falt. n. Silence, darknefs. $. Invertcntia in fmall dofes, nitre, emetic tartar, ipecacuanha eiven fo as to induce naufea. 9. Antacids Art. VII. 3. 9, TORPENTI A. 8 1 9. Antacids. — Soap, tin, alkalies, earths. 10. Medicines preventive of fermentation, acid of vitriql. 1 1. Anthelmintics. — Indian pink, tin, iron, cowhage, amalga- ma, fmoke of tobacco. 12. Lithontriptics, lixiv. faponarium, aqua calcis, fixable air. 1 3. Externally, warm bath, and poultices, oil, fat, wax, platters, oiled filk, carbonic acid gas on cancers, and other ulcers. fcNP OF THE THIRD PART 1 1 II l—l urnwj INDEX TO THE SECTIONS OF PART FIRST, A A. BORTION from fear, xxxix. 6. j. Abforption of folids,xxxiii. 3. 1. xxxvii. of fluids in anafarca, xxxy. I. 3- in warm bath, xxix. 4. 5. A.bforbent veflfels, xxii. 2. xxix. 1. regurgitate their fluids* ixix. 2. their vaives, xxix. 2. communicate with vena portarum, xxvii. 2. Accumulation of fenforial power, iv. 2. xii. 5. 2. Activity of fyftem too great, cure of, xii. 6. to© fmall, cure of, xx. 7. Age, old, xii. 3. 1. xxxvii. 4* Ague-fit, xii. 7. 1. xxxii. 3. 4. xxxii. 9, how cured by bark, xii. 3. 4. periods, how occafioned xii. 2. 3. xxxii. 3. 4. xvii. 3. 6. Ague cakes, xxxii. 7. xxxii. 9, Air, fenfe of frefh, xiv. 8. injures ulcers, xxviii. 4. injected into veins, xxxii. 5. Air-cells of the lungs, xxviii. 2. Alcohol deleterious, xxx. 3. Alliterations, why agreeable, xxii. 2. Aloes in leffened dofes, xii. 3. 1. American natives indolent, xxxi. 2. narrow fhouldered, xxxi. I. Analogy intuitive, Xvii. 3. 7. Animals lefs liable to madnefs,lxxiii. 1. lefs liable to coitagion, xxxiii. z. how to teach, xxii. 3. 2. iheir fimilarity to each other, xxxix. 4. §. fheir changes after nativitv, xxxix. 4. 8. their changes before nativity, xxxix \ 9, ■4 . , • l V y v Animals, lefs liable to contagious di'f- eafes, why, xxxiii. 1. 5. lefs liable to delirium and in* fanity, why, xxxiii. I. 5. eafier to preferve than to re- produce, xxxvii, electricity, xiv. 5. food, diftafte of, xxxviii. r. appetency, xxxix. 4. 7% Animalcula, xxxix. 11. j. from boiling broth, xxxix ZI. z. Antipathy, x. 2. 2. Appetites, xi. 2. 9b xiv. 8* Aphthae, xxviii. Apoplexy, xxxiv. z. 7. not from deficient irrita- tion, xxxii. 2. 1. Architecture, xii. 3.3. xvi. 10. Arts, fine, xxii. 2. Afparagus, its fmell in urine, xxix. Aflbciation defined, ii. 2. z 1. iv. 7. v. 2, affbeiate motions, x. ftronger than irritative ones, xxiv. 2. 8. formed before nativity, xi. 3. with irritative ones, xxiv. 8. with retrograde ones, xxv. 7. xxv. zo. xxv. Z5. difcafes from, xxxv. Aflhma, xviii. 15. Attention, language of, xvi. 8. 64 Atrophy, xxviii. AverfioU, origin of, xi,' 2. 3. B. Balance ourfelves by vifipn, xx. t. Bandage increases abforption, xxxii Barrennefs, xxxvi. 2. 3. Battemcnt of founds, xx. ?. Batb. u INDEX TO THE SECTIONS.—Part I. Bath, cold. See Cold Bath. Bath, warm, xxix. 4. 5. Beauty, fenfe of,jcvi 6. xxii. 2. Bile-dudb, xxx. (tones, xxx. 3. regurgitates into the blood, xxiv. 2. 7. vomiting of xxx. 3. Birds of pailage, xvi. 12. nefb or. xvi. 13. colour of their eggs, xxxix. 5. Biting in pain,xxxiv. i. 3. of mad animals, xxxiv. 1. 3, Black fpots on dice appear red, xl. 3. Bladder, communication of with the inteftines, xxix. 3. of f»fh, xxiv. i. 4. Blood, transfufion of in nervous fevers, xxxii. 4. deficiency of, xxxii^. 2. and 4. from the vena portarum into the inteftines, xxvii. 2. its momentum, xxxii. 5. 2. momentum increafed by vene- fectian, -xxxii. 5. 4. drawn in nervous pains, xxxii. 5- 4- its oxygenation, xxxviii. Breathing, how learnt, xv. 4. Breafta of men, xiv. 8. Brutes differ from men, xi. 2. 3. xvi. 17. See Animals. Buxton bath, why it feels warm, xii. 2. 1. xxxii. 3. 3. C. Capillary veffels are glands, xxvi. 1. Catalepfy, xxxiv. I. 5. Catarrh from cold fkin, xxxv. 1. 3. xxxv. 2. 3. from thin caps in flcep,xviii. 15. Catenation of motions defined, ii. IX. iv. 7. caufe of them, xvii. r. 3. defcribed, xvii. continue fome time after their production, xvii. 1.3. voluntary ones diflcvered in fleep, xvii. 1 . I 2. xvii. Cathartics, external, their operation, xxix. 7. 6. Caufation, animal, defined ii. II. iv. 7. Caufe of caufes, xxxix. 4. 8. Caufes inert and efficient, xxxix. 12. 2. active and paflive, xxxix. 12. 3. proximate and remote, xxxix. 12. 4. Chick in the egg, oxygenation of, xxxviii. 2. Child riding on a flick, xxxiv. 2. 6. Chilnefs after meals, xxi. 3. xxxv. 1. t. Cholera, cafe of, xxv. 13. Chyle, xxxix 11. Circulation in the eye vifible, xl. 10. 4. Cold in the head, xii. 7. J. perceived by the teeth, xxxif. 3. 1. xiv. ,6. air, ufes of in fevers, xxxii. 3. 3. feet, produces coryza, xxxv. 2. 3. xxxv. t. 3. bath, why it flrengthens, xxxii. 3- 2. fhort and cold breathing in it, xxxii. ;<. 2. produces a fever fit, xxxii. 3. 2. tit of fever the confequence of hot fit, xxxii. 9. 3. bathing in pulmonary haemor- rhage, xxvii. I. fits of fever, xxxii. 4. xxxii. 9.. xvii. 3. 3. not a ftimulus, xxxii. 10. Comparing ideas, xv. 3. Confcioufnefs, xv. 3. 4. in dreams, xviii. 13. Ccnfumption, its temperament, xxxi. x. and 2. of dark-eyed patients, xxvii. 2. of light-eyed patients, xxviii. 2. is contagious, xxxiii. 2. 7. Confent of parts. See Sympathy. Contagion, xii- 3. 6. xix. 9. xxxiii. 2. 6. and 8. xxii. 3. 3. docs not enter the blood, xxxiii. 2. lO. xxii. 3. 3. Contraction and attraction, ir. 1. of fibres produces fenfa- tion, iv. 5. xii. I. 6. continues fome time, xii. alternates with relaxation, xii- 1. 3. Convuluon, xvii. 1. 8. xxxiv. 1. 1. and 4. iii. 5. 8. of particular mufcles.xvii. f.8. periods of, xxxvi. 3. 9. Colours of animals, efficient caufe of, xxxix. 5. 1. of eggs from female imagina- tion, xxxix. 5. I« of the choroid coat of the eye, xxxix. 5. 1. of birds' nefts, xvi. 13. Coryza, INDEX TO THE SECTIONS.— Part I, h Coryza. See Catarrh. Cough, nervous, periods of, xxxvi. 3- 9- Cramp, xviii. 15. xxiv. I. 7. Critical days from lunations, xxxvi. 4* Cuckoo, xvi. 13. 5. D, Darkifh room, why we fee well in it. xii. 2. 1. Debility, fenforial and ftimulatory, xii. 2. 1. diretft and indirect of Dr. Brown, xii. 2. 1. xxxii. 3. 2. Sec Weaknefs. from drinking fpirits, cure of, xii. 7. 8. in fevers, cure of, xii. 7. 8. Deliberation, what, xxxiv. 1. Delirium, two kinds of, xxxiii. 1. 4. xxxiv. .2. 2,. cafes of, iii. 5. 8. prevented by dreams, xviii. a. Defire,origin of, xi. 2. 3. Diabetes explained, xxix. 4. with bloody urine, xxvii. 2. in the night, xviii. 15. Diarrhcea, xxix. 4. Pigeftion, xxxiii. r. xxxvii. ftrengthened by emetics, xxxv. i. 3. ftrengthened by regular hours, why, xxxvi, 2. 1. Digitalis, ufe of in dropfy, xxix. 5. 2. Distention acts as a ftimulus, xxxii. 4. See Extenfion. Diftinguifhing, xv. 3. Diurnal circle of actions, x*v. 4. Doubting, xv. 3. Dreams, viii. 1. 2. xiv. 2, 5. their inconCftency, xviii. 16. no furprife in them, xviii. 17. much novelty of combination, xviii. 9, Dropfies explained, xxix 5. 1. Dropfy cured by infanity, xxxiv. 2. 7 . cure of, xxix 5. 2. Drunkennefs. See Intoxication, xxi. diminished by attention, xxi. 8. Drunkards weak till next day, xvii.1.7, ftammer, and dagger, and weep, xii. 4. r. xxi. 4. lee objects double, why, xxi. 7. become delirious, fleepv, ftupid, xxi. 5. Dyfpncca in cold bath, xxxii. 3, 2. E Ear, a good one, xvi. 10, noife in, xx. 7. Eggs of frogs, fifli, fowl, xxxix. %. of birds, why fpotted, xxxix. 5. with double yolk, xxxix. 4. 4. Electricity, xii. 1. xiv. 9. jaundice cured by it,xxx.2, animal, xiv. 5. Embryon produced by the male, xxxix. 2. confifts of a living fibre, xxxix. 4. abforbs nutriment, receives oxygen, xxxix. 1. its actions and fenfations, xvi. 2, Emetic. See vomiting. Emotions, xi. 2. 2. Ennui, or taedeum vitse, xxxiv. 2. 3, xxxiii. 1. 1. xxxix. 6. Epileptic fits explained, xxxiv. 1. 4. xxvii. 2. in fleep, why, xviii. 14. and 15. Equinoxial lunations, xxxii. 6. Excitability perpetually varies,xii. 1.7, fynonymous to quantity of fenforial power, xii. 1. 7. Exercife, its ufe, xxxii. 5. 3. Exertion of fenforial power defined, xii. 2. f. Exiftence in fpace, xiv. 2. 5. Extenfion, fenfe of, xiv. 7. Eyes become black in feme epilepfies, xxvii. 2. F. Face, flufhing of after dinner, xxxv. 1. 1. why firft affected in fmall-pox, xxxv. I. 1. red from inflamed liver, xxxv. 2. 2. Fainting fits, xii. 5. I. xiv. 7. Fear, language of, xvi. 8. 1. a caufe of fever, xxxii. 8. caufe of, xvii. 3. 7. Fetus. See Embryon, xvi. 2. xxxix. I. Fevers, irritative, xxxii. 1. intermittent, xxxii. 1. xxxii. 3. fenfitive, xxxiii. t. not an effort of nature for re- lief, xxxii. 10. paroxyfms of, xii. 7. 1. xii. 2, 3- xii. 3.5. why fome intermit and not others, xxxvi. 1. cold fits of, xxxii. 4, xxxii. 9. xvii, 3. 3. Fcver^ 86 INDEX TO THE SECTIONS.-^art I. fevers, periods of, xxx vi. 3. have folar or lunar periods, xxxii. 6. fource of the fymptoms of, xxxii, 1. proftration of ftrength in, xii. 4. 1. xxxii. 2, 2. cure of, xii. 6. 1. liow cured by the bark, xii. 3.4. cured by increafed volition, xii. 2. 4. xxxiv. 2. 8. belt quantity of flimulus in, xii. 7. 8. Fibres. See Mufdes. their mobility, xii. 1. 7. xii. i.i. contractions of, vi. xii. 1. 1. four clafies of their motions, vi. their motions difiinguifhed fronl fenforial ones, v. 3. Figure, xiv. 2. 2. hi. 1. Fifh, their knowledge, xvi. 14. Foxglove, its ufe in dropfies, xxix. 5. J. overdofe of, xxv. 17. Free-will, xV. 3. 7. & Gall-Hone, xxv. 17. See Bile-froncs. Generation, xxxiii. I. xxxix. Gills of fifh, xxxviii. 2. Glands,xxii. 1. conglobate glands, xxii. 2. have their peculiar ftimuluS, xi. 1. their fenfes, xiv. 9. xxxix. 6. invert their motions, xxv. 7. increafe their motions, xxv. 7. Golden rulefor exhibiting wine, xii. 7. 8. for leavingolFwine,xii.7.8. Gout from inflamed liver, xxxv. 2. 2. xviii. 15. xxiv. 2. 8. in the flomach,xxiv. 2. 8.xxv. 17. why it returns after evacuations, xxxii. 4. owingto vinous fpir it only, xxi.id periods of, xxxvi. 3. 6. Grinning in pain, xxxiv. 1. 3. Gyration on one foot, xx. 5. and 6. H. Habit defined, ii. 11. iv. 7. Haemorrhages, periods of, xxxvi. 3. ix. from paralyfis of veins, xxvii. 1. and 2. iiair and nails, xxxix. 3. %. colour of, xxx'x. .5. 1. Harmony, xx'i. z. } It :»d-a«:hs, XXXV. 2. I. arino, x;v. 4. Heat, fenfe of, xiv. 6. xxxii. 3. 1. produced by the glands, xxxii. 3, external and internal, xxxii. 3. r, atmofphere of heat, xxxii. 3. 1. increafes during fleep, xviii. 15 Hemicrania, xxxv. 2. 1. fiom decaying teetb, xxxv. 2. 1. Flepatitis, caufe of, xxxv. 2. 3. Hereditarv difeafes, xxxix. 7. 6. Hermaphrodite infects, xxxix. 5. Herpes, xxviih 2. from inflamed kidney, xxxv.2.2. Hilarity from diurnal fever, xxxvi. 3.1. Hunger, fenfe of, xiv. 8. Hydrophobia, xxii. 3. 3. Hypochondriacifm, xxxiii. 1. 1. xxxiv. 2. 3- I. tdeas defined, ii, vi. a. 7. are motions of the organs of fenfe, iii. 4. xviii. 5. xviii. 10. xviii. 6. analogous to mufcular motions, iii. 5. • continue fome time, xx. 6. new ones cannot" be invented, iii. 6. I. abftracted ones, iii. 6. 4. xv. 5. inconfiftent trains of, xviii. 16. perifh with the organ of fenfe, Hi. 4. 4. painful from inflammation of the # organ, iii. 5. 5. irritative ones, vii. 1. 4. rii. 3. 2, XV. 2. xx. 7. Of refemblance, contiguity, cauf- ation, viii. 3. 2. x. 3. 3. refemble the figure, and other properties of bodies, xiv. 2. 2. received in tribes, xv. 1. of the fame fenfe ealier combin- ed, xv. 1. 1. of reflection, xv. 1. 6. ii. 12. ideal prcfence, xv. 1. 7. Identity, xv. 3. 5. xviii. 13. Iliac paffion, xxv. 15. Imagination, viii. 1. 2. xv. 1. 7. xv.2.2. of the male forms the fex, xxxix. 6. Immatefial beings, xiv. 1. xiv. 2. 4. Imitation, origin of, xii. 3. 3. xxxix. 5 xxii. 3. xvi. 7. Impediment of fpeech, xviii 1. 10. xvii- 2. 10. Infection. See Contagion. Inflammation, x>ii. 2. 3. xxxiii. 2. 2. great vafcular exertioi ill, xii. 2. I. teflammaticn, INDEX TO THE SECTIONS.— Part I. 8? inflammation not from pains ftom de- fect of famulus, xxxiii. 2. 3. of parts previoufly in- fenfible, xii. 3. 7. often diftant from its caufe, xxiv. 8. obfervcs folar days, xxxii. 6. of the eye, xxxiii. 3. 1. Life, long, art of producing, xxxvii. Light has no momentum, iii. 3. 1. Liquor amnii, xvi. 2. xxxviii. 3. xxxix, 1. 1. is nutritious, xxxviii. 3. frozen, xxxviii. 3. Liver, paralyfis of, xxx. 1. 4. large of geefe, xxx. I. 6. Love, fentimental, its origin, xvi. 6. animal, xiv. 8. xvi. 5. of the bowels prevented Lunar periods affect difeafes, xxxii. 6, by their continued Luft, xiv. 8. xvi. 5. adtioninfleep, xviii.2. Lymphatics, paralyfis of, xxviii. Sec Inoculation with blood, xxxiii. 2. 10. Abforbents. Infanepeople,theirgreat ftrength,xii.i. M. Infanity (fee Madnefs) pleaiurableone, Mad-dog, bite of, xxii. 3. 3. xxxiv. 2. 6. Madnefs, xxxiv. 2. 1. xii. 2. I. Infects, their knowledge, xvi. 15, & 16. Magnetifm, xii. 1. 1. in the heads of calves, xxxix. 1. Magnifying objects.new way of, xl. 10.5, clafs of, xxxix. 4. 8. Male animals have teats, xxxix. 4. 8. Inftinctive actions defined, xvi. 1. pigeons give milk, xxxix. 4. 8. Intefanes, xxv. 3. Man difanguifhed from brutes, xi. 2. Intoxication relieves pain, why, xxi. 3. 3. xvi. 17. from food after fatigue, Material world, xiv. 1. xiv. 2.5. xviii. 7. xxi. 2. Matter, penetrability of, xiv. 2. 3, difeafes from it, xxi. 10. purulent, xxxiii. 2. 4. See Drunkennefs. Mealies, xxxiii. 2. 9. Intuitive analogy, xvii. 3. 7. Membranes, xxvi. 2. Invention, xv. 3. 3. Memory defined, ii. 2. 10. xv. 1.7. xv. 3. Irritability increafes during fieep> Menftruation by lunar periods, xxxii. 6. xviu. 15. Itching, xiv. 9. J- Jaw, locked, xxxiv. 1. 5, Jaundice from paralyfis of the liver, xxx. 2. cured by electricity, xxx. 2. Judgment; xv. 3. K. Knowledge of various animals, xvi. 11. L. Microfcopic animals, xxxix. 11. 5. vegetables, xxxix. it. 1. Mifcarriage from fear, xxxix. 6. 5. Mobilty of fibres, xii. 1.7. Momentum of the blood, xxxii. 5. 2. fometimes increafed by venefection, xxxii. 5. 4. Monfters, xxxix. 4. 4. and 5. 2. without heads, xxxviii. 3. Moon and fun, their influence, xxxii. 6. Mortification, xxxiii. 3. 3. Lacrymal fack, xvi. 8. xxiv. 2. and 7. Motion is either caufe or effect, i. xiv. Lacteals, paralyfis of, xxviii. See Ab- forbents. Lady playing on the harpfichord, xvii. 2. diftrefled for her dying bird, xvii. 2. 10. Language,T\aturaI, its origin,xvi. 7.& 8. of various pailxons defcrib- ed, xvi. 8. 2.2. primary and fecondary, i. animal, i. iii. 1. propenfity to, xxii. r. ^animal, continue fome time after their production, xvii, r. 3- defined, a variation of figure, iii. 1. xiv. 2. 2. xxxix. 7. artificial, of various animals, Mucus, experiments on, xxvi. i. xvi. 9. theory of, xxxix. 8. 3. Lapping of puppies, xvi. 4. Laughter explained, xxxiv. i. 4. from tickling, xvii. 3. 5.. xxxiv. 1. 4. from frivolous ideas? xxxiv. I. 4. xviii, ix. You II, Zza fecretion of, xxvi. 2. Mules, xxxix. 4. 5. and 6. xxxix. 5. 2. Mule plants, xxxix. 2. Mufcae volitantes, xl. 2. Mulcles confatute an organ of fenfc, xiv. 7. ii. 3. famulated by extenfion, xi. I. xiv. 7. Mufcles 88 INDEX TO THE SECTIONS.— Part I. Mufclescontract by fpirit of animation, xii. i. x. and 3. Mufic, xvi. 10. xxii. 2. Mufical time, why agreeable, xii. 3. 3. K\ Naufea, xxv. 6. Kervts and brain, ii. 2. 3. extremities of, form the whole fyftem, xxxvii. 3. arenot changed with age,xxxvii.4. Nervous pains defined, xxxiv. x. X. Number defined, xiv. 2. 2. Nutriment for the embryon, xxxix. 5.2. Nutrition owing to ftimulus, xxxvii. 3. by animal felcetion, xxxvii. 3. when the fibres are elongat- ed, xxxvii. 3. like inflammation, xxxvii. 3. O. Objects long viewed become faint, iii. Ocular fpectra, xl. Oil externally in diabetes, xxix. 4. Old age from inirritability, xxxvii. Opium is Aimulant, xxxii. 2. 2. promotes abforpticn after e- vacuation, xxxiii. 2. 10. in incrcafing dofes, xii. 3. 1. Organs of fenfe, ii. 2. 5. when deftroyed ceafe to pro- duce ideas, iii. 4. 4. Organic particles of Buffon, xxxvii. 3. xxxix. 3. 3- Organ pipes, xx. 7. Oxygenation of the blood, xxxviii. P. Pain from excefs and defect of motion, iv. 5. xii. 5. 3. xxxiv. 1. xxxv. 2. I. not felt during exertion, xxxiv. 1. 2. from greater contraction of fi- bres, xii. 1. 6. from accumulation of fenforial power, xii. 5. 3. xxiii. 3. 1. from light, prellurc, heat, cauf- tics, xiv. 9. in epilepfy, xxxv. 2. I. diflant from its caufe, xxiv. 8. from ftonc in the bladder, xxxv. 2. 1. of head and back from defect of heat, xxxii. 3. from a gali-flone, xxxv. 2. 1. xxv. 17- of the flomach in gout, xxv. 17. of flioulder in hepatite", xxxv. 2.4. jjr'idu».cs volitiou, iv. 6. Palenefs in cold fit, xxxii. 3. 2. Palfies explained, xxxiv. 1. 7. Paralytic limbs flrctch from irritation, vii. 1.3. patients move their found limb much, xii. 5. I. Paralyfis from great exertion, xii. 4. 6. from lefs exertion, xii. 5. 6. of the lacteals, xxviii. of the liver, xxx. 4. of the right arm, why, xxxiv. i- 7 of the veins, xxvii. 2. Particles of matter will not approach, xii. t. I. Pafiicns, xi. 2. 2. connate, xvi. 1. Pecking of chickens, xvi. 4. Perception defined, xv. 3. 1. ii. 2. 8. Periods of agues, how formed, xxxii. 3-4. of difeafes, xxxvi. of natural actions and of dif- eafed actions, xxxvi. Perfpiration in fever-fits, xxxii. 9. See Sweat. Petechix, xxvii. 2 Pigeons fecrete milk in their ftcmachs, xxxix. 4. 8. Piles, xxvii. 2. Placenta a pulmonary organ, xxxviii. 2. Pleafure of life, xxxiii. 1. xxxix. 5. from greater fibrous contrac* tions, xii. I. 6. what kind caufes laughter, xxxiv. 1. 4. what kind caufes fleep, xxxir. I. 4. Pleurify, periods of,xxxvi. 3.7. caufe of, xxxv. %. 3. Prometheus, ftory of, xxx 3. Proflration of ftrength in fevers, xii. 4- 1. Pupils of the eyes large, xxxi. 1. Puife quick in fevers with debilitv, xii. i. 4. xii. 5. 4. xxxii. 2. 1, in fevers with ftrengfh, xxxii. 2. from defect of blood, xxxii. 2. 3. xii. 1. 4 weak from emetics, xxv. 17. Quack advertifements injurious. Pref- ace. (Quadrupeds hav^e no fanguifcrous lo- chia, xxxviii. 2. have nothing fimilar to the yolk cf egg., xxxix. 1. Raph-mia, INDEX TO THE SECTIONS. -Part I. S9 R. S.aphania, periods of, xxxvi. 3. 9. Reafon, ix, r. 2. xv. 3. Reafoning, xv. 3. Recollection, ii. 10. ix. r. 2. xv. 2. 3. Relaxation and bracing, xxxii. 3. 2. Repetition, why agreeable, xii. 3. 3. xxii. 2. Reipiration affected by attention, xxxvi. 2. t. ReftleiTnefs in fevers, xxxiv. r. 2. Retrograde motions, xii. 5. 5. xxv. 6. XX ix. II. of the ftomach, xxv. 6. of the fkin, xxv. 9. •of fluids, how diftiiiguifhed, xxxix. 8. how caufed, xxix. it. 5. Retrograde vegetable motions, xxix. 9. .Retina is fibrous, iii. 2. xl. x. is active in vihon, iii. 3. xl. I. excited into fpafmodic motions, xl. 7. is fenfible during fleep, xviii. 5. xix. 8. Reverie, xix. 1. xxxiv. 3. cafe of a fleep-walker, xix. 2. is an epileptic difeafe, xix. 9. Rhymes in poetry, ivhy agreeable, xxii. 2. Rheumatifm, three kinds of, xxvi. 3. Rocking young children, xxi. 4. Rot in fneep, xxxii. 7. Ruminating animals, xxv. I. S. Saliva produced by mercury, xxiii. by food, xxiii. 1. by ideas, xxiii. 2. and 5. by disordered volition, xxiii. 7. Scirrhous tumours revive, xii. 2. 2. Screaming in pain, xxxiv. 1. 2. ^ Scrofula, its temperament, xxxi. I. xxviii. 2. xxxix. 4. 5. Scurvy of the lungs, xxvii. 2. Sea hcknefs, xx. 4. flopped by attention, xx. 5. Secretion, xxxiii. r. xxxvii. increafed during deep, xviii. 16. Seeds require oxygenation, xxxviii. 2. Senfation defined, ii. 2. 9. v. 2. xxxix. 8.4, difeafes of, xxxiii. from fibrous contractions, iv. 5. xii. 1. 6. in an amputated limb, iii. 7. 3. ail'cdls the whole fenforium, xi. 2. produces volition, iv. 6. Senfibility increases during fleep, xviii. Senlititive motions, viii. xxxiii. 2. xxxiv. 1. f ever* oi two kinds, xxxiii. 1.2 ideas, xv. 2. 2. SenfoTiirm defined, ii. 2. r. Senfes correct one another, xviii. 7. difiinguifhed from appetites, xxxiv. r, 1. Senforial power. See Spirit of Ani- mation, great expenfeof in the vital motions, xxxii. 3. ?. two kinds of excited in fen- fitive fevers, xxxiii. 1. 3, powers defined, v. i, motions diftinguifn^d from fibrous motions, v. 3. not much accumulated in fleep, xviii. 2. powers, accumulation cf, xii. 5- i. exhauftion of, xii. 4. r. wafted below natural in hot fits, xxxii. 9. 3. lefs exertion of produces pain, xii. 5. 3. lefs quantitv of it, xii. 5. 4. Senfual motions diftinguiflied from mufcular, ii. 7. Sex owing to the imagination of the father, xxxiv. 5. xxxix. 7. 6. xxxix. 6. 3. xxxix. 6. 7. Shingles from inflamed kidney, xxxva 2. 2. Shoulders broad, xxxi. r. xxxix. 7. 6. Shuddering from cold, xxxiv. t. j. & 3 Sight, its accuracy in men, xvi. 6. •Skin, fcurfon it, xxvi. 1. Sleep ihfpends volition, xviii. 1. defined, xviii. 21. remote caufes, xviii. 2C. fenfation continues in it, xviii. t. from food, xxi. 1. from rocking, uniform founds. xxi. I. from wine and opium, xxi. 3. why it invigorates, xii. c. j. pulfe flower and fuller in, xxxif. . 2. 2. interrupted, xxvii. 2. from ♦•'breathing; lefs oxv<*cne. xviii. ao. from being whirled on a mi II- flonc, xxiii. 2C from application of cold,xviii.io. induced by regular hours,.\xxvi. 2. 2. Sleeping animals, xxi. 2. 2. Sleep-walkers, See P*cvcrie, x'x. i. Small-pox, INDEX TO THE SECTIONS.— Part I. Small-pox, xxxiii. 2. 6. xxxiv. 6. 1. eruption firft on the face, why, xxxv. 1. 1. xxxiii. 2. IO. the blood will not infect, xxxiii. 2. 10. obeys lunations, xxxvi. 4. Smell, xiv. 5. xvi. 5. Smiling, origin of, xvi. 8. 4. Solidity, xiv. 2. I. Somnambulance Sec Reverie, xix.i. Space, Jtiv. 2. 2. Spafm, doctrine of, xxxii. ro. Spectra, ocular, xl. miftaken for fpectres, xl. 2. vary from long infpection, iii. 3-5. Spirit of animation. Sec Senforiai Power, of animation caufes fibrous con- traction, iv. 2, ii. 1. xiv. 2. 4» poffeffes folidity, figure, and oth- er properties of matter, xiv. 2. 3- Spirit* and angels, xiv. 2. 4. Stammering explained, xvii. I. IO. . xvii. 2. 10. Stimulus defined, ii. 2. 13. iv. 4. xii. 2.1. of various kinds, x>. 1. with leffencd effect, xii. 3 1. with greater eflfect, xii. 3. 3. ceafts to produce fenfation, xii. 3. 3. Stomach and inteftines, xxv. inverted by great ftimulus, xxv. 6. its actions decreafed in vom- iting, xxxv. 1. 3. a blow on it occalicns death, xxv. 17. Stools black, xxvii. 2. Strangury, xx-xv. 2. 1. Sucking before nativity, xvi. 4. Suckling children, fenfe of, xiv. S. SuggefHon defined, ii. 10. xv. 2. 4* Sun and moon, their influence, xxxii. 6. Surprife, xvii. 3.7. xviii. r.7. Sufpicion attends madnefs, xxxiv. 2. 4. Swallowing, act of, xxv. 1. xvi, 4. Sweat, cold, xxv. 9. xxix. 6. in hot fit of fever, xxxii. 9. in a morning, why, xviii. 1 ?. aty hands cured by lime, xxix. 4. 9. Swinging and rocking, why agreeable, xxi. 3. Sympathy, xxxv. I. ucope, xii. 7. 1. xxxiv. 1. 6. T. Txdum vitae. See Ennui. Tape-worm, xxxix. 2. 3. Tafte, fenfe of, xiv. 5. Tears, fecretion of, xxiv. from grief, xvi. 8. 2. from tender pleafure, xvi. 8. jr. from ftimulus of nafal duct, xvi . 8. xxiv. 4. by volition, xxiv. 6. Teeth decaying caufe hcadachs, xxxv. 2. I. Temperaments, xxxi. Theory of medicine, wanted. Preface* Thirft, fenfe of, xiv. 8. why in dropfies, xxix. 5. Tickle themfelves, children cannot,. xvi'- 3. 5. Tickling, xiv. 9. Time, xiv. 2. 2. xviii, 12. lapfe of, xv. 3 . 6. poetical and mulical, why agree- able, xxii. 2. dramatic, xviii. 12. Tooth-edge, xvi. 10. iii. 4. 3. xii. 3. 3.. Touch, fenfe of, xiv. 2. 1. liable to vertigo, xxi. 9. of various animals, xvi. 6. Trains of motions inverted, xii. 5. 5. Transfufion of blood in nervous fever, xxxii. 4- Tranflations of matter, xxix. 7. Typhus, beft quantity of ftimulns in, xii. 7. 8. periods of, obferve lunar days, xxxii. 6. U. Ulcers, art of healing, xxxii. 3. 2. of the lungs, why difficult tc heal, xxviii. 2. Uniformity in the fine arts, why agree- able, xxii. 2. Urine pale in intoxication, xxi. 6. paucity of in anafarca, why, xxix. 5. its paffage from inteftines to bladder, xxix. 3. copious during llcep, xviii. 15. v: Variation, perpetual, of irritability, xii. 2. 1. Vegetable buds arc inferior animals, xiii. I. exactly refemble their parents, xxxix. poffefs fenfation and volition, xiii. 2- Vegetabl* INDEX TO THE SECTIONS.— Part I. 9i Vegetable buds have aflbciate and re- trograde motions, xiii. 4. xxix. 9. their anthers and ftigmas are alive, xiii. 5. Vegetables have organs of fenfe and ideas, xiii. 5. contend for light and air, xxxix. 4. 8. duplicature of their flow- ers, xxxix. 4. 4. Veins are abforbents, xxvii. 1. paralyfis of, xxvii. I. Venereal orgafm of brutes, xxxii. 6. Venefedlion in nervous pains, xxxii.5.4. Verbs of three kinds, xv. 3. 4. Verfes, their meafure, xxii. 2. Vertigo, xx. defined, xx. II. in looking from a tower, xx.i. in a fhip at fea, xx. 4. of all the fenfes, xxi. 9. by intoxication, xxxv. I. a. Vibratory motions perceived after fail- ing, xx. 5. xx. 10. Vinegar makes the. lips pale, xxvii. 1. Vis medicatrix of nature, xxxix. 4. 7. Vifion, fenfe of, xiv. 3. Volition defined, v. a. xxxiv. I. affects the whole fenforium, xi, ». Volition, difeafes of, xxxiv. Voluntary, x. 2. 4. motions, ix. xxxiv. I. ideas, xv. z. 3. criterion of, xi. a. 3. xxxiv. t. Vomiting from vertigo, xx. 8. from drunkennefs, xx. 8. xxi. 6. by intervals, xxv. 8. by voluntary efforts, xxv. 6. of two kinds, xxxv. I. 3. in cold fit of fever, xxxii. 9. 1. flopped by quickfilver, xxv. 16. weakens the pulfe, xxv. 17. W. Waking, how, xviii. 14. Walking, how learnt, xvi. 3. Warmth in fleep, why, xviii. 15. Weaknefs defined, xii. 1. 3. xii. a. 1.' xxxii. 3. a. cure of, xii. 7.8. See De- bility. Wit producing laughter, xxxiv. I. 4* World generated, xxxix. 4. 8. Worm, fluke, xxxii. 7. END OF INDEX TO PART I. [cCj* Part II. and the Index to it, compofe the Second Volume.] Vol. I. Aau INDEX OBS3B l-l'J J.UU-L«-« INDEX OF THE ARTICLES OF PART THIRD. A A. .BSORPTION, iv. 2, r. cutaneous, mucous, cellu- lar, iv. 'i, 2. of the veins, iv. 2, 4. of inflamed vefTeis, iv. 2, 4j 3- ofinteftines and liver, iv. 2,5- of venereal ulcere, iv. 2, 7. not increafed by cold, iv. 2, 1. increafed by opium after evacuation, ii. 2, 1. by faline bath, iv. 2, 3, 8. by abflinencefrom fluids, iv. 2,3,9. Acacia, iv. 3, 5, 2. Acids aufkre, iv. 2, I, 2. iv. 3, I. vegetable, fweet, vii. 3,4.iv.2, 1,2. mineral, vii, 3, 6. Acrid plants, iv. 2, 4. Agriculture, i. 2, 3, 7. Agues, three kinds, iv. 2, 3, 2. iv. 2, 5. iv. 2, 6, 8. Air nourifhes, i. 2, 5. warm bath of, iv. 2, 3, 8. Alcali vol. iii. 3, 3. Alcohol, ii. 2, I. v. 2, 4. Almond, bitter, ii. 3, 1. Althasa, iii. 3, 3, 3. Allium, iii. 3, 3. Aloe, iii. 2, 5. iii. 2,7. iii. 3, 5, 5. vi. 2, 5. Alum, iii. 2, 1. iv. 2, 1. iv. 2, 5, 2. iv. 3, 5, 5- to purify water, i. 2, 4, 2. Amalgama in worm?, vii. 2, 2. Amomum zinziber, iii. 3, I, Amber, oil of, vi. 3, 4. Ammoniac gum, vi. 3, i, iii. 5, 3. fait or fpirit, iii. 3, 3. Anarfarca, warm bath in, ii. 2, 2. iv. 2, 3,8. Anchovy, iii. 2, I. iii. 3, 1,4. ^ Animal food, i. 2, 1, 1. Antimony prepared, iii. 3, 1, 5. iii. 2, I. iv. I, TO. Anthemis nobilis, iv. 3, 3. pyrethrum, iii. 3, 2. Anxiety, v. 2, 4. Apium, petrofelinum, iii. 3,4, 4. Apoplexy, iv. 2, 11. Ariflclochia ferpentaria, iii. 3, 1. Armenian bole, vi. 2, 3. vi. 3, 5, 3. Arfenic in ague, iv. 2, 6, 8. iv. 3, 6. Saturated iblution of, iv. 2, 6, 8. in itch, iv. 2, 9. how it a<5ls, iv. 2, 6, 9. how to detect it, iv. 2, 6, 10. Artemifia maritima, iv. 3, 3. abfynthium, iv. 3, 3. fantonicum, iv. 3, 3. Articheke-leaves, iv. 3, 3. Aiafeetida, ii. 3. vi. 3, I. Afarum Europeum, v. 3, 3. Afcarides, vii. 1, 2. iii. 2, 9, 7. Afparagus, iii. 3, 4,4. Aftragalus tragacantha, iii. 3, 3, 3. Atropa belladonna, ii. 3, 1. Azote, i. 2, 5. B. Balfams diuretic, iii. 2, 4. Bandages promote ahforption, iv. 2. 1*. Bark, Peruvian, iv. 2, 2. long ufed noxious, iv. 2, 11. Barley, iii. 3, 3, 3. Bath, warm, ii. 2, 2, I, iii. j, I, 6, iii, 3>3> 4- i'i- 2, 3,3. faline, iv. 2, 3, 8. of warm air, iv, 2, 3, 8. Bath, INDEX OF THE ARTICLES.— Part III. 93 Bath, of fleam, iv. 2,3,2. cold, vii. 2, 3. nutritive, i. 2, 6, 1. Benzoin, iii. 3, 3. Bile of animals, iii. 2, 5, 2. dilute date of, iv. 2, 6. Blifters, how they act, iii. 2, 1, 10. cure heart-burn, iii. a, 1, 10. flop vomiting, vi. 2, 2. produce expectoration, iii. 2, 3> 2- increafe perfpiration, iii. 2, I. 10. Blood, transfufion of, i. 2, 6, 2. Bog-bean, iv. 3, 3. Bole armenian,iv. 2, 5, 3. Bone-afhes, iv. 3, 5, 3. Bowels, inflammation of, v. 2, 2, 2. Bryony, white, iii. 3, 8. as a blifter, iii. z, 9. Butter, i. 2, 3, 2. Butter-milk, i. 2, 2, 2. C. Cabbage-leaves, vii. 1, 2. Calcareous earth, i. 2, 4, 3. Calomel, iii. 2, .5. vi. 2, 5. in enteritis, v. 2, 2, 2. Camphor, iii. 3, 1. Canella alba, iii. 3, 1. Cantharides, iii. 2, 6, iii. 2, 8. v. 2, 4. vi. 2, 4. Capillary action increafed by tobacco, iv.2, 3, 7. Capflcum, iii. 3, 1. Carbonic acid gas, vii. 2, 6. Cardamomum,iii. 3, 1. Caryophyllus aromat. iii, 3, I. Cardamine, iv. 3, 4. Caflia fiflul. iii. 3,5, j. fenna, iii. 3, 5.5. Caftor, vi. 2, I. vi. 3, r. Cathartics, mild, iii. 2, 5. violent, v. 2, 2. CerufTa in ulcers, iv. 2, 9. iv. 2, 7, Chalk, iv. 3, 5,3, Chalybeate, iv. 3,4, 2. iv. 3, 6,6, Chalybeate powder, iv. 2, 6, 6. Cheefe, i. 2, 2, 3. Cherries, black, ii. 2, I, 8. Chioroiis, iv. 2, 6, 5. Cicuta, ii. 3, 1. Cinchona, iv. 2, 2. Cinnamon, iii. 3, 2, Clay, iv. 3, 5, 3. Cloves, iii. 3, 1. iii. 3, 2- Cnicus acarna, v. 3, 1. Cocculus indicus, ii. 3, r. Cochlearia armoracia, iii. 3, S. iv. 3,4, hortenlis, iv. 3, 4. Cold, continued application of, vii. 2,3. interrupted, vii. 2, 3. iii. 3, 1, 7. exceflive, vii. 2, 3. firft effects lymphatics, vii. 2, 3. produces rheum from the nofe, vii. 2, 3. produces quick anhelation, vii. 3,3- increafes digeflion, vii. 2, 3. Cold-fit eafier prevented than remov- ed, ii. 2, I. Colic from lead, v. 2, 2, 2. Condiments, i. 2, 7. Convolvulus fcammonium, v. 3,2. Convulfions, iv. 2, 8. Cookery, i. 2, 3, 5. Copaiva balfam, iii. 3, 4, 3. Cowhage, iii. 2, 7. vii. 3, 11. Crab-juice, iv. 2, 2. Cream, i. 2,3, 2. i. 2, 2, 2. Cucumis colocynthis, v. 3, 2. Cynara fcolymus, iv. 3, 3. Cynogloffum, ii. 3, 1. D. Dandelion, iv. 3, 4. Datura flramonium, ii. 3, I. Daucus fylveflxis, iii. 3, 4,4. Delphinium ftavifagria, ii. 3, I. Diabetes, iv, 2, 5. warm bath in, vi. 2, 4. Diaphoretics, iii. 3,1. iii. a, 1,2. beft in the morning, iii. 2S Diarrhoea, vi. 2, 3. Digeflion injured by cold, iii. 2, 1. increafed by cold, vii. 2, 3. Digitalis, iv. 2, 3, 7. v. 2, I, 2. tincture of, iv. 2, 3, 7. Dragon's blood, iv. 3, 5, 2. Dropfy, iv. 2, 3,4. iv.2, 6, 7. iv.2, 3, 7- E. Ears, eruption behind, iv. 2, 9, %> Earth of bones, iv, 2, 5. of alum, vi. 2, 4. calcareous, iv. 2, 5, 3. vi. 2, 4. i. 2,4> 3- Eggs, i. %, i, 4- Egg-ihells diuretic, iii. 2, 4. Electricity, ii. 2, 2, 2. iv. 2, 9, P'metics, how they act, v. 2, I. J rrhines mild, iii. 2, 9. in hydrocephalus, v. 2, 3, 1 violent, v. 2, 3. in head-ach, v. 2, 3, I. Eryfipelas, iv. 2, 9. Eflential oil?, ii. 2, 3. . E.thc- , *4 INDEX OF THE ARTICLES. -Part III. Ether, vitriolic, ii. 2. 3. iii. 3. I. vi. 3-7- in afcaf ides, vii. r. 2. to purify, ii. 1. 3. Etiolation,!. 2. 3. 4. Euphorbium, v. 3. 3. Exercife, iii. 3. 1. 6. ii. 2. 6. Eyes inflamed, ii. 2. 2. 2. iv. 2. 3. F. Famine, times of, i. 2.3. 5. and 6. Fear, v. 2. 4. Feathers, fmoke of, vi. 3. 6. Fennel, iii. 3. 4. 4. Ferula afafcetida, iii. 3. 3. Fifh, i. 2. 1. 2. i. 2 1.5. Flannel fhirt, ii. 2. 2. 1. Flefh of animals, i. 2. I. Fluke-worm, iv. 2. 6. Foxglove, iv. 2. 3. 7. v. 2. 1. v. 2. 4. tincture of, iv. 2. 3. 7. Friction, ii. 2. 5. iii. 3. 1. 6. G. Galanthus nivalis, vii. 3. 3. Galbanum, vi. 3. 1. Gall-Hones, iv. 2. 6. Galls of oak, iv. 3. 5. Garlic, iii. 3. 3. Gentiana centaurcum, iv. 3. 3. lutea, iv. 3. 3. Ginger, iii. 3. 1. iii. 3. 4. Gonorrhoea, iv. 2. 2. iii. 2.4. Gout, iv. 2. 11. 2. Guaiacum,iii.3. 1. Gum arahic, iii. 3. 3. 3. tragacanth, iii. 3. 3. 3. Glycyrrhiza glabra, iii. 3. 3. 3. Gravel, v. 2. 4. 4. a Hartfhorn, fpirit and fait of, iii. 3. 3. iii. 3. 1. vi. 3.4. calcined, iv. 2. 3. vi. 2. 3. Hemorrhages, iv. 2. 4. 4. iv. a. 6. 2. Hsematoxylon campechianuni, iv. 3. 5. 2. Hay, infufion of. i. 2. 3. 6. Head-ach, fnuff in, v. 2. 3. 1. Heat, ii. 2. 2. r. SeeEalli. an univcrfal folvent, vii. 2. 2. Helenium, iii. 3. 3. 2. Herpes, iv. 2. 1. iv. 2. 9. Herrings, red, iii. 3. 1. 4. Honey, iii. 3. 3.3. iii. 3.5. 1. Hop in beer, why noxious, iv. 2. 3. 6. iv. 2. 11. 2. Hordeum diftichon, iii. 3. 3. 3. Humulus lupulus, iv. 2. 3. iv. 2. 1 r. Hydrargyria vitriolatus, v. 2. 3. Hyfleric difeafe, vi. 2. 1. pains, vi. 2. 1. convnlfions, vi. 2. 1. I. Jalapium, iii. 3. 5. 5. Japan earth, iv. 3. 5. 2. Jaundice, iv. 2. 6. 3. Ileus, vi. 2. 5. Incitantia, ii. Intermittents. See Agues. Inverted motions, vi. 2. i. in hyfleric difeafe, vi. 2. 1. of the flomach, vi . 2. 2. inteftinal ca- nal, vi. 2.5. of lymphatics,vi.2.3 . Inula helenium, iii. 3. 3. 2. Ipecacuanha, v. 2. 1. Iron, ruft of, iv. 3. 6. Irritability prevented, iv. 2. 3. 3. Itch, iv. 2. 1. 3. Inflammation of the bowels, v. 2. 2. 2 , L. Laurus camphora, iii. 3. 1. cinnamomum, iii. 3. 1. faflafras, iii. 3. 1. Lead, iv. 3. 6. colic from, v. 2. 2. 2. fugar of, iv. 2. 9. Leeks, iii. 3. 3 1. Lege, ulcers of, iv. 2. ID. fwelled, iv. 2. 3. 8. Lemon-juice, iv. 2. 1. iv. 2. 2. Lcontodon taraxacum, iv. 3. 4. Life fhortentd by great ftimukis, i. 1. Lime, i. 2.4. 3. Liquorice, iii. 3. 3. 3. Liver inflamed, iv. 2. 6. Logwood, iv. 3. 5. 2. Lymphatics, inverted motions of,v.2.i. M. Manganefe, ii. 2. 4. Magnelia alba, iii. 3. 5. 3. Malt, i. 2. 3. 5. Manna, iii. 3. 5. Marfh-mailows, iii. 3. 3 Marjoram, iii. 3. 9. Marum, iii. 3. 9. MafHch, iii. 3. 2. iii. 3. 3. Menianthes trifoliata, iv. 3. 3. Menifpcrnmm coccnl:: , 11. 3. /. Menftruation promoted, iv. 2. 6. 6. reprefled, iv. 2. 6. 6. Mercury, iii. 3. 2. vi. 2. 2. jweparations of, iv. 3. 7. iv. 2 7. iv. 2. 9. injected a^ a cl) ftcr, vi. 3. j. Metallic fait*, iv. 2. 6. Milk, i. 2. 2. Mimofa nilotica, iii. ?. *. t. catechu, iv. 3. 3. 2. at, INDEX OF THE ARTICLES.— Part III. 95 Mint, vi. 3. 3. Mortification, iv. 2. 9. Mucilage, vegetable, vii. 3. 3. Mucus, animal, vii. 3. 5. Mufhrooms, i. 2. t. 2. Mufk, vi. 2. 1. vi. 3. 1. Muftard, iv. 3. 4. See Sinapifm. N. Naufea, in fevers, vii. 2.5. Neutral falts diuretic, why, iii. 2. 4. increafe fome coughs, iii. 2. 4- increafe heat of urine, iii. 2. 4. Nicotiana tabacum, iii. 3. 9. ii. 3. I. Nitre, iii. 3. 4. v. 2. 4. Nutmeg, iii. 2. I. Nutrientia, i. O. Oil of ahnonds, iii. 3. 5. 4. in cream, i. 2. 3. 2. of amber, vi. 2. 1. exprefTed, externally, iii. 2. 3, effential, ii. 2, 3. iii. 3. 2. Oiled iilk, vii. 3. 13. Oleum animale, vi. 2. 1. vi. 3. 4. ricini, iii. 3. 5. 4. Onions, iii. 3. 3. Opium, ii. 2. I. 2. iv. 1. 2. in nervous pains, ii. 2. 1. 5. in inflammatory pains, ii. 2. 1.6. increafes all fecreuons and ab- forptions, ii. 2. I. 1. abforption after evacuation, iv. 2. 8. 2. ii. 2. 1.3. flops fweats, iv. 2, 1.2. intoxicates, ii. 2. 1. 1. Oranges, their peel, iv. 3. 3. Orchis, vii. 3.3. Oxygen gas, ii. 2. 4- i- 2- 5. iii- 2. It. iv. 1.4. produces and heals ulcers, iv. 2. 7. P. Pains, periodic, cured by opium, ii. 2. 1. Papin's digefler, i. 2. 3. 5. Papaver fomniferum, ii. 3. 1. iv. 3. 2* See Opium. v Pareira brava, iii. 3. 4. 4. Parflcy, iii. 3- 4. Paffions, ii. 2. 5. Paflurage. i. 2. 3. 7. Pepper, iii. 3. x. Pcripneumony, iv. 2. 8. 2. Perfpiration in a morning, iii. 2. r. not an excicment, iii. 2. 1. Peru, balfa'm of, iii. 3. j. 4. Petechia;, iv. 2. 4. 2. Pimento, iii. 3. 1. Piper indicum, iii. 3. 1. Piftacla leniilcus, iii. 3. 2, Pix liquida, iii. 3. 2. Phofphorus, iii. 2. 6. Plafter-bandage, iv. 2. 10. Pleurify, iv. 2. 8. 2. Polygala feneka, iii. 3. 3. 2, Poppy. See Papaver. Portland's powder noxious, why, iv. 2. 11. 2. Potatoe-bread,i. 2. 3.4. Potentilla, iv. 3. 5. Powder of iron, iv. 2. 6. 6. Prunes, iii. 3. 5. I. Prunus demeflica, iii. 3. 5. I. fpinofa, iv. 3. 1. lauro-cerafus, ii. 3. 1. Pulegium, vi. 3. 3. Pulfe, intermittent, relieved by arfenic, iv.,2. 6. Pyrethrum, iii. 3. 2. Pyrus malus, vLi. cydonia, iv. 3. 1. Quaffia, iv. 2. 2. Quince, iv. 3. 1. Quinquefolium, iv. 3. 5. R. Ratifia, why deflru&ive, ii. 2. I. Reaction, iv. 1. 10. Refin diuretic, iii. 2. 4. vi. 2. 4. Rhamnus catharticus, v. 3. 2. Rheumatifm, iv. 2. 4. 5. iv. 2. 10. 2. Rheum palmatum. See Rhubarb. Rhubarb, iii. 2. 1. iv. 2. 5. X. iii. 3. 5. 5. caufes conflipation, why, iii. 2. 1. I- Rice, vii. Rofes, iv. 3. 5. Rot in fheep, iv. 2. 6. S. Sagapenum, vi. 3..1. Sago, vii. 3. Salivation not neceflary, iv. 2. 7* hyflcric, v. 2. 3. Salt, common, unwholefome,iii. 1. 12. muriatic, iii. 3. I. in clyflers, iii. 2. 7. Salt?, -why diuretic, iii. 2. 4. neutral, iii. 3. 5. 3. iii. 2. 4. improper in coughs and gonor- rhoea, iii. 2. 4. Salt-fifh and fait meat increafe perfpi- ration, iii. 2. 1. Saflafra.-*, iii. 3. 1. Scammunv, v. 2. 2. Scarcity, times of, i. 2. 3. 5. and 6. Scilla, maritima, v. 2. 2. iv. 2. 3. iii. 3. 3. v. 2. 3. Scorbutic legs, iv. 2. 10. Scrofulous tumours, ii. 2. 4. iv. 2. 9. Sea-water, iii. 3. 5. 3. Secernentia, iii. Secretion 96 iNDEX OF THE ARTICLES.— Part III, Secretion cf the bladder, iii. 2. 6. redtum,iii. 2. 7. {kin, iii. 2. 8. Seneka. iii 3. 3. 2. Senna, iii. 3. 5. 5. Serpentai ia verginiana, iii. 3. 1. Sialagogues, iii. 2. 2. v. 2. 3. Simarouba, iv. 3. 5. Sinapi. iv. 3. 4. Sinapifms, vi. 2. 2. iii. 2.8, S'iiymbrium natlurtium, iv. 3. 4. Sloes, iv. 2. 2. Snuff in head-ach,v. 2. 3. I. Sceerrhines. Snuffs of candles, vi. 3. 4. Society, i. 2. 3. 7. Soot,vi. 3.4. Sorbentia, various kinds, iv. 2. 1. Spafmodic doctrine exploded, vii. 2. 3. Spermaceti, iii, 3. 3. 3. Spice, noxious, iii. 1. 12. Spirit of wine noxious, ii. 2. I. Sponge, burnt, vi. 3. 4. Squill. See Scilla. Starch, i. 2. 3. t. from poifonous roots>i. 2. 3. 4. Steam, bath of, iv. 2. 3. 8. Steel, iv. 2. 6. 1. forwards and reprcffes menftrua- tion, iv. 2. 6. 6. powder, iv. 1. 6. 6. Stizolohium filiqua hirfuta, iii. 2. 7. vii. 3. 1 1. Strychnos nux vomica, ii. 3. 1. Sublimate of mercury, iv. 2.7. iv. 2 9. Sugar nourilhing, i. 2. 3. 1. and 5. iii. formed after the death of the plant, i. 2. 3. 5. aperient, iii. 3. 5. I. Sulphur, iii. 3. 5. 4. Sweats in a morning, iii. 2. I. I. on waking, iii. 2. I. I. cold, v. 2. 5. flopped by opium, iv. 2. 1. 2. T. Taenia, vermes. See Worms. Tamarinds, iii. 3. 5. 1. Tanfey,tanacctum,iv. 3.3. Tar, iii. 3. 3. . Tartar, cryftals of, iii. 3. 5. 1 • Ci^fs 1 2. 3. 13. vitriolate, ii'. 3- 5- 3- emetic, v. 2. 1. v. 2. 2. Tea, vii. 5. 1. Te?r?, iii. 2. 10. Teftaccous powders, iv. 2. 2. Tetradynamia, plants of, iv. 2. 4. Ti of digitalis, iv. z- 3- 7- Tinea, herpes, iv. %. 1. 4. Tobacco.ii. 3. 1. iii. 3.9. iv. 2. 3. R. injures digeftion, iii. 2- 2. 3. Tolu balfam, iii. 3. 3. Tonics, iv. 1. 10. Tormentiila eredta, iv. 3. 5. Torpentia, vii. Tragacanth gum, iii. 3. 3. 3. Turpentine, vi. 2. 4. fpirit of, iii. 2. 6. Turpeth mineral, v. 2. 3. TuiTUago farfara,iii. 3. 3. 3. U. Ulcer9 cured by bandage, iv. 2. 10. fcrofulous, iv. 2.9. of the mouth, iv. 2. 2. cured by abforption, ii. 2. I. a* iv. 2. 3. 5. iv. 2.7. Uva urfi, iv. 3. 5. V. Valerian, vi. 3. 3. Vegetable acids, iv. 2. 1. food, i. 2. 1. 2. Venereal ulcers, iv. 2. 7. Venefeclion, vii. 2.4. iv. 2. 8. diminifhes fecretions, vii. 2. 4. increafes abforptions, vii. 2. 4. Veratrum, V. 3. 2.. Vibices, iv. 2. 4 3. Vinegar, iv. 2. 1. 9. iv. 3. 4. 3. ii. 2. 1. 9 Vitriol blue in agues, iv. 2. 6. iv. 2. 2. in ulcers, iv. 2. 9. white, iv. 3. 6. v. 2. x. acid of, iv. 2. I. in fweats, iv. r. I. in.fmall-pox, iv. 1. r. Volatile fait, vi. 3. 6. Vomiting, v. 2. 2. flopped by mercury, vi. 2. 2v Vomits, iv. 2. 3.7. W. Warm-bath, ii. 2. 2. 1. falinc, iv. 2 3. 8. in diabetes, vi. 2. 4. Water, i. 2. 4. dilutes and lubricates, vii. 2. 2. cold, produces fweats, iii. 2. I. iced, in ileus, vi. 2. 5. crefles, iv. 3. 4. Whey of milk, iii. 3. 5. 2. i. 2. 2. 2. Willow, bark, iv. 2. 3. 2. Wine, ii. 3. I. Worms, vii. i- 2, iii. 2. 7. iv. 2. 6. 4. in fheep, iv. 2. 6. 4. Wounds cured by bandage, iv. 2. 10. 2. Z. qc, vitriol of, v. 3. 1. DIRECTIONS to the BINDER. 3* Pleafe to place the Plate confiding of one red fpot, at Seel. III. i. page 9. 2. Confuting of one black fpot, at Sect. III. 3. 3. page 12. 3. Confifting of five concentric coloured circles, at Seel. III. 3. 6. page 13. 4. Conlifling of one yellow circle furrounded by one blue one, at Seel. XL. 4. 2. page 451. 5. Confiding of one yellow circle and two blue ones, at Seel. XL. 10. 3. page 462. 6. . Confifting of the word BANKS in blue on a yellow ground, at Seel. XL. 10. 5. page 465. Hi >■ / 'I * 21 ' ;• ^^ • v w EL*£ §1 '■■■' ■/••: 1 • v*"